Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
The property of blood capillary ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-NERVE BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.
Cell-cell junctions that seal adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other. (Alberts et al., Molecular Biology of the Cell, 2nd ed, p22)
Specialized non-fenestrated tightly-joined ENDOTHELIAL CELLS with TIGHT JUNCTIONS that form a transport barrier for certain substances between the cerebral capillaries and the BRAIN tissue.
A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p887)
A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity.
Proteins involved in the transport of specific substances across the membranes of the MITOCHONDRIA.
The property of dentin that permits passage of light, heat, cold, and chemical substances. It does not include penetration by microorganisms.
An azo dye used in blood volume and cardiac output measurement by the dye dilution method. It is very soluble, strongly bound to plasma albumin, and disappears very slowly.
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A MARVEL domain protein that plays an important role in the formation and regulation of the TIGHT JUNCTION paracellular permeability barrier.
Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.
Uptake of substances through the lining of the INTESTINES.
A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.
An increase in MITOCHONDRIAL VOLUME due to an influx of fluid; it occurs in hypotonic solutions due to osmotic pressure and in isotonic solutions as a result of altered permeability of the membranes of respiring mitochondria.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
The resistance to the flow of either alternating or direct electrical current.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
Human colonic ADENOCARCINOMA cells that are able to express differentiation features characteristic of mature intestinal cells, such as ENTEROCYTES. These cells are valuable in vitro tools for studies related to intestinal cell function and differentiation.
Aquaporin 1 forms a water-specific channel that is constitutively expressed at the PLASMA MEMBRANE of ERYTHROCYTES and KIDNEY TUBULES, PROXIMAL. It provides these cells with a high permeability to WATER. In humans polymorphisms of this protein result in the Colton blood group antigen.
A 195-kDa zonula occludens protein that is distinguished by the presence of a ZU5 domain at the C-terminal of the molecule.
A group of glucose polymers made by certain bacteria. Dextrans are used therapeutically as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation and in industry for a wide variety of purposes.
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.
A specialized transport barrier, in the EYE, formed by the retinal pigment EPITHELIUM, and the ENDOTHELIUM of the BLOOD VESSELS of the RETINA. TIGHT JUNCTIONS joining adjacent cells keep the barrier between cells continuous.
Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
A phthalic indicator dye that appears yellow-green in normal tear film and bright green in a more alkaline medium such as the aqueous humor.
Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)
Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.
The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
Water-soluble proteins found in egg whites, blood, lymph, and other tissues and fluids. They coagulate upon heating.
A family of peptidyl-prolyl cis-trans isomerases that bind to CYCLOSPORINS and regulate the IMMUNE SYSTEM. EC 5.2.1.-
Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.
Highly specialized EPITHELIAL CELLS that line the HEART; BLOOD VESSELS; and lymph vessels, forming the ENDOTHELIUM. They are polygonal in shape and joined together by TIGHT JUNCTIONS. The tight junctions allow for variable permeability to specific macromolecules that are transported across the endothelial layer.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.
A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.
A starch found in the tubers and roots of many plants. Since it is hydrolyzable to FRUCTOSE, it is classified as a fructosan. It has been used in physiologic investigation for determination of the rate of glomerular function.
A large family of transmembrane proteins found in TIGHT JUNCTIONS. They take part in the formation of paracellular barriers and pores that regulate paracellular permeability.
Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)
A claudin subtype that is found localized to TIGHT JUNCTIONS in VASCULAR ENDOTHELIAL CELLS. The protein was initially identified as one of several proteins which are deleted in VELOCARDIOFACIAL SYNDROME and may play an important role in maintaining the integrity of the BLOOD-BRAIN BARRIER.
Elements of limited time intervals, contributing to particular results or situations.
Fluorescent probe capable of being conjugated to tissue and proteins. It is used as a label in fluorescent antibody staining procedures as well as protein- and amino acid-binding techniques.
The original member of the family of endothelial cell growth factors referred to as VASCULAR ENDOTHELIAL GROWTH FACTORS. Vascular endothelial growth factor-A was originally isolated from tumor cells and referred to as "tumor angiogenesis factor" and "vascular permeability factor". Although expressed at high levels in certain tumor-derived cells it is produced by a wide variety of cell types. In addition to stimulating vascular growth and vascular permeability it may play a role in stimulating VASODILATION via NITRIC OXIDE-dependent pathways. Alternative splicing of the mRNA for vascular endothelial growth factor A results in several isoforms of the protein being produced.
The barrier between capillary blood and alveolar air comprising the alveolar EPITHELIUM and capillary ENDOTHELIUM with their adherent BASEMENT MEMBRANE and EPITHELIAL CELL cytoplasm. PULMONARY GAS EXCHANGE occurs across this membrane.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
Uptake of substances through the SKIN.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Mitochondria in hepatocytes. As in all mitochondria, there are an outer membrane and an inner membrane, together creating two separate mitochondrial compartments: the internal matrix space and a much narrower intermembrane space. In the liver mitochondrion, an estimated 67% of the total mitochondrial proteins is located in the matrix. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p343-4)
Excessive accumulation of extravascular fluid in the lung, an indication of a serious underlying disease or disorder. Pulmonary edema prevents efficient PULMONARY GAS EXCHANGE in the PULMONARY ALVEOLI, and can be life-threatening.
The ability of a substrate to allow the passage of ELECTRONS.
A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.
Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
A cyclic undecapeptide from an extract of soil fungi. It is a powerful immunosupressant with a specific action on T-lymphocytes. It is used for the prophylaxis of graft rejection in organ and tissue transplantation. (From Martindale, The Extra Pharmacopoeia, 30th ed).
The minute vessels that connect the arterioles and venules.
One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Proteins that take part in the formation or structure of TIGHT JUNCTIONS.
A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.
Devices used in a technique by which cells or tissues are grown in vitro or, by implantation, in vivo within chambers permeable to diffusion of solutes across the chamber walls. The chambers are used for studies of drug effects, osmotic responses, cytogenic and immunologic phenomena, metabolism, etc., and include tissue cages.
The rate dynamics in chemical or physical systems.
Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.
The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.
Fluids composed mainly of water found within the body.
The circulation of the BLOOD through the MICROVASCULAR NETWORK.
Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.
A family of angiogenic proteins that are closely-related to VASCULAR ENDOTHELIAL GROWTH FACTOR A. They play an important role in the growth and differentiation of vascular as well as lymphatic endothelial cells.
A family of voltage-gated eukaryotic porins that form aqueous channels. They play an essential role in mitochondrial CELL MEMBRANE PERMEABILITY, are often regulated by BCL-2 PROTO-ONCOGENE PROTEINS, and have been implicated in APOPTOSIS.
An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.
An integral membrane protein that is localized to TIGHT JUNCTIONS, where it plays a role in controlling the paracellular permeability of polarized cells. Mutations in the gene for claudin-1 are associated with Neonatal Ichthyosis-Sclerosing Cholangitis (NISCH) Syndrome.
An antibiotic produced by Pseudomonas cocovenenans. It is an inhibitor of MITOCHONDRIAL ADP, ATP TRANSLOCASES. Specifically, it blocks adenine nucleotide efflux from mitochondria by enhancing membrane binding.
The minute vessels that collect blood from the capillary plexuses and join together to form veins.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
These growth factors are soluble mitogens secreted by a variety of organs. The factors are a mixture of two single chain polypeptides which have affinity to heparin. Their molecular weight are organ and species dependent. They have mitogenic and chemotactic effects and can stimulate endothelial cells to grow and synthesize DNA. The factors are related to both the basic and acidic FIBROBLAST GROWTH FACTORS but have different amino acid sequences.
An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.
Soluble protein factors generated by activated lymphocytes that affect other cells, primarily those involved in cellular immunity.
Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.
Abnormal fluid accumulation in TISSUES or body cavities. Most cases of edema are present under the SKIN in SUBCUTANEOUS TISSUE.
Anchoring points where the CYTOSKELETON of neighboring cells are connected to each other. They are composed of specialized areas of the plasma membrane where bundles of the ACTIN CYTOSKELETON attach to the membrane through the transmembrane linkers, CADHERINS, which in turn attach through their extracellular domains to cadherins in the neighboring cell membranes. In sheets of cells, they form into adhesion belts (zonula adherens) that go all the way around a cell.
Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
A glycoside of a kaurene type diterpene that is found in some plants including Atractylis gummifera (ATRACTYLIS); COFFEE; XANTHIUM, and CALLILEPIS. Toxicity is due to inhibition of ADENINE NUCLEOTIDE TRANSLOCASE.
The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.
An enzyme isolated from horseradish which is able to act as an antigen. It is frequently used as a histochemical tracer for light and electron microscopy. Its antigenicity has permitted its use as a combined antigen and marker in experimental immunology.
Treatment process involving the injection of fluid into an organ or tissue.
A methylpentose whose L- isomer is found naturally in many plant glycosides and some gram-negative bacterial lipopolysaccharides.
The relationship between the dose of an administered drug and the response of the organism to the drug.
The balance of fluid in the BODY FLUID COMPARTMENTS; total BODY WATER; BLOOD VOLUME; EXTRACELLULAR SPACE; INTRACELLULAR SPACE, maintained by processes in the body that regulate the intake and excretion of WATER and ELECTROLYTES, particularly SODIUM and POTASSIUM.
An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Measurement of light given off by fluorescein in order to assess the integrity of various ocular barriers. The method is used to investigate the blood-aqueous barrier, blood-retinal barrier, aqueous flow measurements, corneal endothelial permeability, and tear flow dynamics.
Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.
The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).
The mitochondria of the myocardium.
Established cell cultures that have the potential to propagate indefinitely.
Normal human serum albumin mildly iodinated with radioactive iodine (131-I) which has a half-life of 8 days, and emits beta and gamma rays. It is used as a diagnostic aid in blood volume determination. (from Merck Index, 11th ed)
Mutant strains of mice that produce little or no hair.
Unstable isotopes of chromium that decay or disintegrate emitting radiation. Cr atoms with atomic weights of 46-49, 51, 55, and 56 are radioactive chromium isotopes.
A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.
Calcium-dependent cell adhesion proteins. They are important in the formation of ADHERENS JUNCTIONS between cells. Cadherins are classified by their distinct immunological and tissue specificities, either by letters (E- for epithelial, N- for neural, and P- for placental cadherins) or by numbers (cadherin-12 or N-cadherin 2 for brain-cadherin). Cadherins promote cell adhesion via a homophilic mechanism as in the construction of tissues and of the whole animal body.
Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.
Stable potassium atoms that have the same atomic number as the element potassium, but differ in atomic weight. K-41 is a stable potassium isotope.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Aquaporin 3 is an aquaglyceroporin that is expressed in the KIDNEY COLLECTING DUCTS and is constitutively localized at the basolateral MEMBRANE.
A chelating agent that sequesters a variety of polyvalent cations such as CALCIUM. It is used in pharmaceutical manufacturing and as a food additive.
Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES.
Chemicals and substances that impart color including soluble dyes and insoluble pigments. They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS.
The finer blood vessels of the vasculature that are generally less than 100 microns in internal diameter.
Aquaporin 4 is the major water-selective channel in the CENTRAL NERVOUS SYSTEM of mammals.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
The middle portion of the SMALL INTESTINE, between DUODENUM and ILEUM. It represents about 2/5 of the remaining portion of the small intestine below duodenum.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
The pressure required to prevent the passage of solvent through a semipermeable membrane that separates a pure solvent from a solution of the solvent and solute or that separates different concentrations of a solution. It is proportional to the osmolality of the solution.
Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.
The blood vessels which supply and drain the RETINA.
One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
A layer of epithelium that lines the heart, blood vessels (ENDOTHELIUM, VASCULAR), lymph vessels (ENDOTHELIUM, LYMPHATIC), and the serous cavities of the body.
Lanthanum. The prototypical element in the rare earth family of metals. It has the atomic symbol La, atomic number 57, and atomic weight 138.91. Lanthanide ion is used in experimental biology as a calcium antagonist; lanthanum oxide improves the optical properties of glass.
The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.
The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).
An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
A nonapeptide messenger that is enzymatically produced from KALLIDIN in the blood where it is a potent but short-lived agent of arteriolar dilation and increased capillary permeability. Bradykinin is also released from MAST CELLS during asthma attacks, from gut walls as a gastrointestinal vasodilator, from damaged tissues as a pain signal, and may be a neurotransmitter.
Connections between cells which allow passage of small molecules and electric current. Gap junctions were first described anatomically as regions of close apposition between cells with a narrow (1-2 nm) gap between cell membranes. The variety in the properties of gap junctions is reflected in the number of CONNEXINS, the family of proteins which form the junctions.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
The carbohydrate-rich zone on the cell surface. This zone can be visualized by a variety of stains as well as by its affinity for lectins. Although most of the carbohydrate is attached to intrinsic plasma membrane molecules, the glycocalyx usually also contains both glycoproteins and proteoglycans that have been secreted into the extracellular space and then adsorbed onto the cell surface. (Alberts et al., Molecular Biology of the Cell, 3d ed, p502)
A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The passage of viable bacteria from the GASTROINTESTINAL TRACT to extra-intestinal sites, such as the mesenteric lymph node complex, liver, spleen, kidney, and blood. Factors that promote bacterial translocation include overgrowth with gram-negative enteric bacilli, impaired host immune defenses, and injury to the INTESTINAL MUCOSA resulting in increased intestinal permeability. Bacterial translocation from the lung to the circulation is also possible and sometimes accompanies MECHANICAL VENTILATION.
Antidiuretic hormones released by the NEUROHYPOPHYSIS of all vertebrates (structure varies with species) to regulate water balance and OSMOLARITY. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a CYSTINE. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the KIDNEY COLLECTING DUCTS to increase water reabsorption, increase blood volume and blood pressure.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.
A technetium imaging agent used in renal scintigraphy, computed tomography, lung ventilation imaging, gastrointestinal scintigraphy, and many other procedures which employ radionuclide imaging agents.
Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla.
The portion of the GASTROINTESTINAL TRACT between the PYLORUS of the STOMACH and the ILEOCECAL VALVE of the LARGE INTESTINE. It is divisible into three portions: the DUODENUM, the JEJUNUM, and the ILEUM.
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
A cluster of convoluted capillaries beginning at each nephric tubule in the kidney and held together by connective tissue.
The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.
Serum albumin from cows, commonly used in in vitro biological studies. (From Stedman, 25th ed)
Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.
Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.
A class of nucleotide translocases found abundantly in mitochondria that function as integral components of the inner mitochondrial membrane. They facilitate the exchange of ADP and ATP between the cytosol and the mitochondria, thereby linking the subcellular compartments of ATP production to those of ATP utilization.
The escape of diagnostic or therapeutic material from the vessel into which it is introduced into the surrounding tissue or body cavity.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
The selectively permeable barrier, in the EYE, formed by the nonpigmented layer of the EPITHELIUM of the CILIARY BODY, and the ENDOTHELIUM of the BLOOD VESSELS of the IRIS. TIGHT JUNCTIONS joining adjacent cells keep the barrier between cells continuous.
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
Cytochromes of the c type that are found in eukaryotic MITOCHONDRIA. They serve as redox intermediates that accept electrons from MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX III and transfer them to MITOCHONDRIAL ELECTRON TRANSPORT COMPLEX IV.
The property of TEETH to permit passage of light, heat, gases, liquids, metabolites, mineral ions and other substances. It does not include the penetration of the teeth by microorganisms.
Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries (see HYPOXIA, BRAIN). An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive HYDROCEPHALUS). (From Childs Nerv Syst 1992 Sep; 8(6):301-6)
A four-carbon sugar that is found in algae, fungi, and lichens. It is twice as sweet as sucrose and can be used as a coronary vasodilator.
Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.
The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.
The circulation of the BLOOD through the LUNGS.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.
Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.
A proton ionophore that is commonly used as an uncoupling agent in biochemical studies.
A claudin subtype that takes part in maintaining the barrier-forming property of TIGHT JUNCTIONS. Claudin-4 is found associated with CLAUDIN-8 in the KIDNEY COLLECTING DUCT where it may play a role in paracellular chloride ion reabsorption.
A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.
Positively charged atoms, radicals or group of atoms with a valence of plus 1, which travel to the cathode or negative pole during electrolysis.
A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.
Stable sodium atoms that have the same atomic number as the element sodium, but differ in atomic weight. Na-23 is a stable sodium isotope.
Dynamic and kinetic mechanisms of exogenous chemical and DRUG LIBERATION; ABSORPTION; BIOLOGICAL TRANSPORT; TISSUE DISTRIBUTION; BIOTRANSFORMATION; elimination; and DRUG TOXICITY as a function of dosage, and rate of METABOLISM. LADMER, ADME and ADMET are abbreviations for liberation, absorption, distribution, metabolism, elimination, and toxicology.
The interstitial fluid that is in the LYMPHATIC SYSTEM.
Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A generic grouping for dihydric alcohols with the hydroxy groups (-OH) located on different carbon atoms. They are viscous liquids with high boiling points for their molecular weights.
A ubiquitously-expressed claudin subtype that acts as a general barrier-forming protein in TIGHT JUNCTIONS. Elevated expression of claudin-3 is found in a variety of tumor cell types, suggesting its role as a therapeutic target for specific ANTINEOPLASTIC AGENTS.
A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.
Mercury chloride (HgCl2). A highly toxic compound that volatizes slightly at ordinary temperature and appreciably at 100 degrees C. It is corrosive to mucous membranes and used as a topical antiseptic and disinfectant.
A group of cytochromes with covalent thioether linkages between either or both of the vinyl side chains of protoheme and the protein. (Enzyme Nomenclature, 1992, p539)
An inorganic dye used in microscopy for differential staining and as a diagnostic reagent. In research this compound is used to study changes in cytoplasmic concentrations of calcium. Ruthenium red inhibits calcium transport through membrane channels.
A membrane of squamous EPITHELIAL CELLS, the mesothelial cells, covered by apical MICROVILLI that allow rapid absorption of fluid and particles in the PERITONEAL CAVITY. The peritoneum is divided into parietal and visceral components. The parietal peritoneum covers the inside of the ABDOMINAL WALL. The visceral peritoneum covers the intraperitoneal organs. The double-layered peritoneum forms the MESENTERY that suspends these organs from the abdominal wall.
Quaternary ammonium analog of ethidium; an intercalating dye with a specific affinity to certain forms of DNA and, used as diiodide, to separate them in density gradients; also forms fluorescent complexes with cholinesterase which it inhibits.
Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).
Adverse functional, metabolic, or structural changes in ischemic tissues resulting from the restoration of blood flow to the tissue (REPERFUSION), including swelling; HEMORRHAGE; NECROSIS; and damage from FREE RADICALS. The most common instance is MYOCARDIAL REPERFUSION INJURY.
A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
A cyclododecadepsipeptide ionophore antibiotic produced by Streptomyces fulvissimus and related to the enniatins. It is composed of 3 moles each of L-valine, D-alpha-hydroxyisovaleric acid, D-valine, and L-lactic acid linked alternately to form a 36-membered ring. (From Merck Index, 11th ed) Valinomycin is a potassium selective ionophore and is commonly used as a tool in biochemical studies.
A phospholipid derivative formed by PLATELETS; BASOPHILS; NEUTROPHILS; MONOCYTES; and MACROPHAGES. It is a potent platelet aggregating agent and inducer of systemic anaphylactic symptoms, including HYPOTENSION; THROMBOCYTOPENIA; NEUTROPENIA; and BRONCHOCONSTRICTION.
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Solutions that have a greater osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid.
Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid.
A pathological process characterized by injury or destruction of tissues caused by a variety of cytologic and chemical reactions. It is usually manifested by typical signs of pain, heat, redness, swelling, and loss of function.
A family of 3,6-di(substituted-amino)-9-benzoate derivatives of xanthene that are used as dyes and as indicators for various metals; also used as fluorescent tracers in histochemistry.
A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, and sweetening agent.

Reduced water permeability and altered ultrastructure in thin descending limb of Henle in aquaporin-1 null mice. (1/5437)

It has been controversial whether high water permeability in the thin descending limb of Henle (TDLH) is required for formation of a concentrated urine by the kidney. Freeze-fracture electron microscopy (FFEM) of rat TDLH has shown an exceptionally high density of intramembrane particles (IMPs), which were proposed to consist of tetramers of aquaporin-1 (AQP1) water channels. In this study, transepithelial osmotic water permeability (Pf) was measured in isolated perfused segments (0.5-1 mm) of TDLH in wild-type (+/+), AQP1 heterozygous (+/-), and AQP1 null (-/-) mice. Pf was measured at 37 degrees C using a 100 mM bath-to-lumen osmotic gradient of raffinose, and fluorescein isothiocyanate (FITC)-dextran as the luminal volume marker. Pf was (in cm/s): 0.26 +/- 0.02 ([+/+]; SE, n = 9 tubules), 0.21 +/- 0.01 ([+/-]; n = 12), and 0.031 +/- 0.007 ([-/-]; n = 6) (P < 0.02, [+/+] vs. [+/-]; P < 0.0001, [+/+] vs. [-/-]). FFEM of kidney medulla showed remarkably fewer IMPs in TDLH from (-/-) vs. (+/+) and (+/-) mice. IMP densities were (in microm-2, SD, 5-12 micrographs): 5,880 +/- 238 (+/+); 5,780 +/- 450 (+/-); and 877 +/- 420 (-/-). IMP size distribution analysis revealed mean IMP diameters of 8.4 nm ([+/+] and [+/-]) and 5.2 nm ([-/-]). These results demonstrate that AQP1 is the principal water channel in TDLH and support the view that osmotic equilibration along TDLH by water transport plays a key role in the renal countercurrent concentrating mechanism. The similar Pf and AQP1 expression in TDLH of (+/+) and (+/-) mice was an unexpected finding that probably accounts for the unimpaired urinary concentrating ability in (+/-) mice.  (+info)

Involvement of tumor necrosis factor alpha and interleukin-1beta in enhancement of pentylenetetrazole-induced seizures caused by Shigella dysenteriae. (2/5437)

Neurologic manifestations, mainly convulsions, are the most frequent extraintestinal complications of shigellosis. We used an animal model to study the roles of tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) in Shigella-related seizures. Administration of Shigella dysenteriae 60R sonicate enhanced the sensitivity of mice to the proconvulsant pentylenetetrazole (PTZ) within 7 h. This was indicated by a significantly higher mean convulsion score and an increased number of mice responding with clonic-tonic seizures in the Shigella-pretreated group. Preinjection of mice with anti-murine TNF-alpha (anti-mTNF-alpha) or anti-murine IL-1beta (anti-mIL-1beta) 30 min prior to administration of Shigella sonicate abolished their enhanced response to PTZ at 7 h. Mean convulsion scores were reduced by anti-mTNF-alpha from 1.2 to 0.8 (P = 0.017) and by anti-mIL-1beta from 1.3 to 0.7 (P = 0.008). Preinjection of anti-mTNF-alpha also reduced the percentage of mice responding with clonic-tonic seizures, from 48 to 29% (P = 0.002), and preinjection of anti-mIL-1beta reduced it from 53 to 21% (P = 0. 012). Neutralization of TNF-alpha or IL-1beta did not protect the mice from death due to S. dysenteriae 60R. These findings indicate that TNF-alpha and IL-1beta play a role in the very early sensitization of the central nervous system to convulsive activity after S. dysenteriae administration. Similar mechanisms may trigger neurologic disturbances in other infectious diseases.  (+info)

Transport of solutes through cartilage: permeability to large molecules. (3/5437)

A review of the transport of solutes through articular cartilage is given, with special reference to the effect of variations in matrix composition. Some physiological implications of our findings are discussed. Also, results of an experimental study of the permeability of articular cartilage to large globular proteins are presented. Because of the very low partition coefficients of large solutes between cartilage and an external solution new experimental techniques had to be devised, particularly for the study of diffusion. The partition coefficients of solutes were found to decrease very steeply with increase in size, up to serum albumin. There was, however, no further decrease for IGG. The diffusion coefficient of serum albumin in cartilage was relatively high (one quarter of the value in aqueous solution). These two facts taken together suggest that there may be a very small fraction of relatively large pores in cartilage through which the transport of large molecules is taking place. The permeability of cartilage to large molecules is extremely sensitive to variations in the glycosaminoglycan content: for a threefold increase in the latter there is a hundredfold decrease in the partition coefficient. For cartilage of fixed charge density around 0-19 m-equiv/g, there is no penetration at all of globular proteins of size equal to or larger than serum albumin.  (+info)

Drug-protein binding and blood-brain barrier permeability. (4/5437)

The permeability surface area (PS) product, an index of permeability of the blood-brain barrier (BBB), was measured by using the in situ perfusion method. In the cerebral circulation, the fraction of drug that permeates into the brain through the BBB is not only the unbound fraction but also the fraction dissociated from the protein in the perfusate. The sum of these two fractions, the apparent exchangeable fraction, was estimated by fitting the parameters of the BBB permeability under the condition of varying BSA concentrations in the perfusate. The unbound fraction of drugs in a buffer containing 0.5 mM BSA was measured by using the ultrafiltration method in vitro, and the apparent exchangeable fraction was measured in vivo by using the intracarotid artery injection method. The apparent exchange fraction was 100% for S-8510, 96.5% for diazepam, 90.9% for caffeine, 38.3% for S-312-d, 33.1% for propranolol, and 6.68% for (+)-S-145 Na, and each of these was higher than the corresponding unbound fraction in vitro in all drugs. The apparent exchangeable fractions, for example, were 8 times higher for diazepam and 38 times for S-312-d than the unbound fractions in vitro. The apparent exchangeable fraction of drugs was also estimated from the parameters obtained with the perfusion method. Because drugs can be infused for an arbitrary length of time in the perfusion method, substances with low permeability can be measured. The apparent exchangeable fractions obtained with this method were almost the same as those obtained with the intracarotid artery injection method.  (+info)

Effects of inhibitors and substitutes for chloride in lumen on p-aminohippurate transport by isolated perfused rabbit renal proximal tubules. (5/5437)

The transport step for p-aminohippurate (PAH) from cell to lumen across the luminal membrane of rabbit proximal tubules has not been adequately defined. To examine this process more closely, we determined the effects of possible transport inhibitors and substitutes for chloride on PAH secretion in isolated perfused S2 segments of rabbit proximal tubules. The addition of 4-acetamido-4'-isothiocyano-2,2' disulfonic stilbene (10(-4) M) to the perfusate irreversibly inhibited PAH secretion, whereas the addition of probenecid (10(-4) M) to the perfusate reversibly inhibited PAH secretion. PAH secretion was unaffected by thiocyanate replacement of chloride in the luminal perfusate, reversibly inhibited by 15 to 20% by methyl sulfate replacement, and irreversibly inhibited by isethionate replacement. Because the luminal membrane is at least as permeable to thiocyanate as to chloride, less permeable to methyl sulfate, and much less permeable to isethionate, these data suggest that the PAH transport step from cells to lumen does not require chloride in the lumen but does require a highly permeant anion. During inhibition of PAH transport from cells to lumen, PAH uptake across the basolateral membrane was also reduced, suggesting some type of feedback inhibition. The data are compatible with PAH transport across the luminal membrane by an anion exchanger, a potential-driven uniporter, both carriers, or a carrier that can function in both modes.  (+info)

Selectivity and permeation in calcium release channel of cardiac muscle: alkali metal ions. (6/5437)

Current was measured from single open channels of the calcium release channel (CRC) of cardiac sarcoplasmic reticulum (over the range +/-180 mV) in pure and mixed solutions (e.g., biionic conditions) of the alkali metal ions Li+, K+, Na+, Rb+, Cs+, ranging in concentration from 25 mM to 2 M. The current-voltage (I-V) relations were analyzed by an extension of the Poisson-Nernst-Planck (PNP) formulation of electrodiffusion, which includes local chemical interaction described by an offset in chemical potential, which likely reflects the difference in dehydration/solvation/rehydration energies in the entry/exit steps of permeation. The theory fits all of the data with few adjustable parameters: the diffusion coefficient of each ion species, the average effective charge distribution on the wall of the pore, and an offset in chemical potential for lithium and sodium ions. In particular, the theory explains the discrepancy between "selectivities" defined by conductance sequence and "selectivities" determined by the permeability ratios (i.e., reversal potentials) in biionic conditions. The extended PNP formulation seems to offer a successful combined treatment of selectivity and permeation. Conductance selectivity in this channel arises mostly from friction: different species of ions have different diffusion coefficients in the channel. Permeability selectivity of an ion is determined by its electrochemical potential gradient and local chemical interaction with the channel. Neither selectivity (in CRC) seems to involve different electrostatic interaction of different ions with the channel protein, even though the ions have widely varying diameters.  (+info)

Modulation of slow inactivation in human cardiac Kv1.5 channels by extra- and intracellular permeant cations. (7/5437)

1. The properties and regulation of slow inactivation by intracellular and extracellular cations in the human heart K+ channel hKv1.5 have been investigated. Extensive NH2- and COOH-terminal deletions outside the central core of transmembrane domains did not affect the degree of inactivation. 2. The voltage dependence of steady-state inactivation curves of hKv1.5 channels was unchanged in Rb+ and Cs+, compared with K+, but biexponential inactivation over 10 s was reduced from approximately 100 % of peak current in Na+ to approximately 65 % in K+, approximately 50 % in Rb+ and approximately 30 % in Cs+. This occurred as a result of a decrease in both fast and slow components of inactivation, with little change in inactivation time constants. 3. Changes in extracellular cation species and concentration (5-300 mM) had only small effects on the rates of inactivation and recovery from inactivation (tau recovery approximately 1 s). Mutation of residues at a putative regulatory site at R487 in the outer pore mouth did not affect slow inactivation or recovery from inactivation of hKv1.5, although sensitivity to extracellular TEA was conferred. 4. Symmetrical reduction of both intra- and extracellular cation concentrations accelerated and augmented both components of inactivation of K+ (Kd = 34.7 mM) and Cs+ (Kd = 20.5 mM) currents. These effects could be quantitatively accounted for by unilateral reduction of intracellular K+ (K+i) (Kd = 43.4 mM) or Cs+i with constant 135 mM external ion concentrations. 5. We conclude that inactivation and recovery from inactivation in hKv1.5 were not typically C-type in nature. However, the ion species dependence of inactivation was still closely coupled to ion permeation through the pore. Intracellular ion modulatory actions were more potent than extracellular actions, although still of relatively low affinity. These results suggest the presence of ion binding sites capable of regulating inactivation located on both intracellular and extracellular sides of the pore selectivity filter.  (+info)

Genetic selection of mutations in the high affinity K+ transporter HKT1 that define functions of a loop site for reduced Na+ permeability and increased Na+ tolerance. (8/5437)

Potassium is an important macronutrient required for plant growth, whereas sodium (Na+) can be toxic at high concentrations. The wheat K+ uptake transporter HKT1 has been shown to function in yeast and oocytes as a high affinity K+-Na+ cotransporter, and as a low affinity Na+ transporter at high external Na+. A previous study showed that point mutations in HKT1, which confer enhancement of Na+ tolerance to yeast, can be isolated by genetic selection. Here we report on the isolation of mutations in new domains of HKT1 showing further large increases in Na+ tolerance. By selection in a Na+ ATPase deletion mutant of yeast that shows a high Na+ sensitivity, new HKT1 mutants at positions Gln-270 and Asn-365 were isolated. Several independent mutations were isolated at the Asn-365 site. N365S dramatically increased Na+ tolerance in yeast compared with all other HKT1 mutants. Cation uptake experiments in yeast and biophysical characterization in Xenopus oocytes showed that the mechanisms underlying the Na+ tolerance conferred by the N365S mutant were: reduced inhibition of high affinity Rb+ (K+) uptake at high Na+ concentrations, reduced low affinity Na+ uptake, and reduced Na+ to K+ content ratios in yeast. In addition, the N365S mutant could be clearly distinguished from less Na+-tolerant HKT1 mutants by a markedly decreased relative permeability for Na+ at high Na+ concentrations. The new mutations contribute to the identification of new functional domains and an amino acid in a loop domain that is involved in cation specificity of a plant high affinity K+ transporter and will be valuable for molecular analyses of Na+ transport mechanisms and stress in plants.  (+info)

TY - GEN. T1 - Permeability measurement methods in porous media. T2 - 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008. AU - Sharma, Sanjay. AU - Siginer, Dennis A.. PY - 2009/9/15. Y1 - 2009/9/15. N2 - Accurate measurement of Permeability is critical for fluid flow modeling in porous media. Various experimental methods have been devised that measure permeability as a porous material property. These experiments are based most commonly on Darcys law. Liquid flow and gas flow methods of permeability measurement for in-plane and transverse directions are detailed. Issues related to these methods are discussed. Some associated permeability models are discussed. Alternative methods of permeability determination based on cross transport phenomenon are presented.. AB - Accurate measurement of Permeability is critical for fluid flow modeling in porous media. Various experimental methods have been devised that measure permeability as a porous material property. These ...
TY - JOUR. T1 - Effect of aging and caloric restriction on intestinal permeability. AU - Ma, Thomas Y.. AU - Hollander, Daniel. AU - Dadufalza, Violeta. AU - Krugliak, Pavel. PY - 1992. Y1 - 1992. N2 - Intestinal permeability is increased in several disorders such as Crohns disease or rheumatoid arthritis. Since aging leads to alteration of many biological functions, the effect of aging on intestinal permeability was studied by measuring the intestinal permeability in aging rats gavaged with different size permeability probes- mannitol, polyethylene glycol (PEG) 400, and inulin. In rats fed with control diet, there was a significant increase in intestinal permeability to medium size probes PEG 400 (14.8 ± 0.4 and 21.0 ± 1.1% at 3 and 28 months respectively, p , .01) and mannitol (3.41 ± 0.4 and 5.3 ± 0.5% at 3 and 28 months, respectively, p , .01). Intestinal permeability of the large macromolecule inulin did not change (0.42 ± 0.03 and 0.38 ± 0.02% at 3 and 28 months, respectively) with ...
The design of new austenitic alloys based on the Fe-Ni-Cr system requires knowledge of their oxygen permeability. Data are available for pure Fe and Ni but not for Fe-Ni alloys. Wagners model for internal oxidation is used to evaluate the oxygen permeability in Fe-Ni alloys. Internal oxidation of Fe-Ni-Cr alloys carried out at 1150 and 1100 °C in Rhines packs and H2/H2O mixtures is described. Internal oxidation produces zones of FeCr2O4 and Cr2O3 precipitates, according to parabolic kinetics. Permeabilities are deduced taking into account interfacial diffusion contributions. Oxygen permeability decreases with nickel addition in a non-ideal way, and oxygen permeability in nickel-rich alloys is independent of the studied environments. However, the oxygen permeability in iron at the highest temperature studied is increased in H2/H2O.
TY - JOUR. T1 - Intestinal permeability increases with the severity of abdominal trauma: a comparison between gas liquid chromatographic and enzymatic method. AU - Gasbarrini, Giovanni Battista. AU - Mingrone, Geltrude. AU - Liverani, E. AU - Silveri, Ng. PY - 2000. Y1 - 2000. N2 - Increased intestinal permeability was found in humans after multiple trauma, burn injury and major vascular surgery. However, no data are reported regarding possible correlation between trauma and intestinal permeability degree. This study was undertaken to compare gas-liquid chromatographic and enzymatic method for the evaluation of intestinal permeability impairment in patients after severe abdominal trauma.. AB - Increased intestinal permeability was found in humans after multiple trauma, burn injury and major vascular surgery. However, no data are reported regarding possible correlation between trauma and intestinal permeability degree. This study was undertaken to compare gas-liquid chromatographic and enzymatic ...
TY - GEN. T1 - Permeability measurement of orthotropic fibers under an acoustic force field. AU - Sharma, Sanjay. AU - Siginer, Dennis. PY - 2009/12/1. Y1 - 2009/12/1. N2 - Using the validated acoustic method of determining physical properties of porous materials, acoustical properties of the orthotropic medium is used to predict longitudinal and transverse permeability. Measurement of samples in the impedance tube is conducted using ASTM E 1050 for a frequency range of 50 Hz to 6.4 KHz. The acoustical method is shown to compute longitudinal and transverse permeability for various porosity levels. The method describes permeability prediction for carbon, glass and hybrid lay ups. Longitudinal permeability calculated from the absorption coefficient of sized and unsized fibers is found to be the same in contrast to the flow methods.. AB - Using the validated acoustic method of determining physical properties of porous materials, acoustical properties of the orthotropic medium is used to predict ...
TY - CHAP. T1 - THREE DIMENSIONAL PERMEABILITY MEASUREMENTS.. AU - Morita, Nobuo. AU - Gray, K. E.. PY - 1980. Y1 - 1980. N2 - Procedures are provided to calculate principal permeabilities and directions from data obtained with a whole core type permeameter which has radial and axial flow measurement capabilities with two openings attached to cylindrical curved surface. The conventional plug method to determine anisotropic permeability was also modified to improve its accuracy; plug number and sample spacing were rigorously designed using error sensitivity numbers. To check the validity of the apparatus, experiments were run using anisotropic Berea sandstone.. AB - Procedures are provided to calculate principal permeabilities and directions from data obtained with a whole core type permeameter which has radial and axial flow measurement capabilities with two openings attached to cylindrical curved surface. The conventional plug method to determine anisotropic permeability was also modified to ...
The Caco-2 permeability assay provides a measure of the permeability of a test compound across the intestinal barrier and its potential for interactions with drug transporters. We provide permeability assays for small molecule formulations such as pharmaceuticals, industrial chemicals and consumer products.
Although polymorphonuclear leukocytes (PMNs) can migrate through every epithelium in the body regardless of its permeability, very little is known about the effect of epithelial permeability on PMN migration and the effect of emigrating PMNs on the permeability of the epithelium. In an in vitro model system of transepithelial migration, human PMNs were stimulated by 0.1 micrometer fMet-Leu-Phe to traverse confluent, polarized canine kidney epithelial monolayers of varying permeabilities. Epithelial permeability was determined by both conductance measurement and horseradish peroxidase (HRP) tracer studies. As epithelial permeability increased, the number of PMN invasion sites as well as the number of PMNs that traversed the monolayer increased. The effect of PMN migration on epithelial permeability was examined using the ultrastructural tracers HRP and lanthanum nitrate. PMNs traversing the monolayer made close cell-to-cell contacts with other invading PMNs and with adjacent epithelial ...
The relative permeability is the ratio … Permeability is a property that quantifies the ability to flow or transmit fluids through a rock when a single fluid is present in pore space.5 Absolute permeability quantifies this relationship when the fluid being transmitted is water.5 The use of core analysis was applied during this study At high water saturations, the oil exists as disconnected droplets occupying the centers of pores. Air permeability at different overburden pressures [131]. Relative permeability is defined as a ration of effective permeability to an absolute permeability of rock. . Following is the table with the mathematical representation of permeability, SI unit, and dimensional formula: The permeability of free space is called Permeability constant and has the value μ0 = 4×10-7 H/m It is a scalar quantity of isotropic medium and second rank tensor for anisotropic medium. In studies [129, 130] with very low permeability sandstones, liquid per-meabilities were found to be less ...
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TY - PAT. T1 - Compositions and Methods for Enhancing Paracellular Permeability across Epithelial and Endothelial Barriers. AU - Thakker,Dhiren R.. AU - Ward,Peter D.. N1 - Status: published applicationnumber: 09/974,519 usclass: 514/75 ; 514/642; 514/76; 514/946 applicationnumber: 09/974,519. PY - 1800. Y1 - 1800. N2 - Compositions and methods for enhancing paracellular permeability at an absorption site in a subject are disclosed. The method includes: (a) administering an effective amount of a phospholipase C inhibitor to a subject at a time in which enhanced paracellular permeability is desired; and (b) enhancing paracellular permeability in the subject at the absorption site through the administering of the effective amount of the phospholipase C inhibitor. The disclosed compositions and methods provide enhanced absorption of a hydrophilic drug in a subject.. AB - Compositions and methods for enhancing paracellular permeability at an absorption site in a subject are disclosed. The method ...
TY - GEN. T1 - Combined effects of laminae characteristics and matrix-fracture equilibrium hysteresis on permeability evolution of fractured sorbing rocks. AU - Zeng, Jie. AU - Liu, Jishan. AU - Li, Wai. AU - Leong, Yee Kwong. AU - Elsworth, Derek. AU - Guo, Jianchun. N1 - Funding Information: This work is supported by the Australian Research Council under Grant DP200101293, UWA China Scholarships, and the China Scholarship Council (CSC No. 201707970011).. PY - 2020. Y1 - 2020. N2 - Permeability is a critical property of fractured sorbing rocks, such as shale and coal, as it controls the gas transport. However, two distinctive features are commonly not simultaneously included in existing permeability models. One is the stratified feature which has been evidenced by an appreciable number of laboratory investigations. The second one is matrix-fracture non-equilibrium induced matrix-fracture interactions during permeability measurement or field operations. The goal of this research is to uncover ...
Acceptor-type doping of perovskite-type La1-x,SrxGa0.80-y,MgyM0.20O3-delta (x = 0-0.20, y = 0.15-0.20, M = Fe, Co, Ni) leads to significant enhancement of the oxygen permeability due to increasing oxygen vacancy concentration and, thus, ionic conductivity. The increase in strontium and magnesium content is accompanied, however, with increasing role of the surface exchange kinetics as a permeation-limiting factor. At temperatures below 1223 K, the oxygen permeation (OP) fluxes through dense La(Sr)Ga(Mg,M)O3-delta membranes with the thickness less than 1.5 mm are mainly limited by the exchange rate at membrane/gas boundaries. For transition metal-containing La(Sr)Ga(Mg)O3-delta (LSGM) ceramics, the oxygen transport increases in the sequence Co < Fe < Ni. The highest permeation is observed for La0.90Sr0.10Ga0.65Mg0.15Ni0.20O3-delta perovskite membranes, which exhibit level of the oxygen permeability similar to that of La(Sr)Fe(Co)O3-delta and La2NiO4-based solid solutions. The average thermal expansion
Recovery of hydrocarbon gas in micro-Darcy rock is now becoming more common-place for gas producers. As part of the reservoir characterization associated with these systems, it is required to understand parameters such as the total porosity and permeability of the system, but also the initial water saturation and the effective gas permeability at this connate water saturation. This is still under the realm of what is termed routine core analysis, but in these tight formations it is imperative to understand that these tests are actually very non-routine by nature. Current work presents a case study of core analysis that was run on plugs from a tight gas producing formation, and illustrates some of the pitfalls and corrections associated with measurements of this low permeability rock. The case study combines low field NMR measurements with core flooding measurements of porosity and permeability. Cores are initially tested at their connate water saturations: NMR measures the initial water ...
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TY - GEN. T1 - Hydraulic permeability and electro-kinetic properties of charged-hydrated tissues during permeation. AU - Gu, W. Y.. AU - Lai, W. M.. AU - Mow, V. C.. PY - 1992/12/1. Y1 - 1992/12/1. N2 - The functional dependences of hydraulic permeability and electrokinetic properties on the composition and material properties of charged hydrated tissues (e.g., articular cartilage) during a one dimensional steady permeation experiment have been derived using the recently developed triphasic theory [Lai et al., 1991]. The results showed that these properties vary within the tissue due to physical interactions between the flowing fluid (including the flowing ions) and the charged porous-permeable solid matrix. Fundamental relationships governing these effects depend on the tissue water content, fixed charge density, solid matrix elastic moduli (i.e., strain-dependent permeability) and the frictional coefficients between the porous-permeable solid matrix and the interstitial fluid. In addition, a ...
Among the most critical factors for geological CO2 storage site screening, selection and operation is effective simulation of multiphase flow and transport. Relative permeability is probably the greatest source of potential uncertainty in multiphase flow simulation, second only to intrinsic permeability heterogeneity. The specific relative permeability relationship assigned greatly impacts forecasts of CO2 trapping mechanisms, phase behavior, and long-term plume movement. A primary goal of this study is to evaluate the impacts and implications on CO2-EOR model forecasts of different methods of assigning relative permeability relationships.. We applied a novel approach to assigning relative permeability relationships in numerical models. In previous research, most models assign relative permeability functions on the basis of geologic formation or rock type. In this study, we assign and calibrate relative permeability by hydrostratigraphic units, extending the seminal work of Maxey (1964) to ...
Filter permeability is a significant term used to measure the endothelial permeability to fluid. There exist permeable sheath in the walls of the filter that allows the fluid (oil, fuel, water) to get in and out. Amongst the numerous methods of measuring micro vascular permeability to fluids infiltration, filter permeability aces.. What Is The Need For Filter Permeability?. In simple language, filtering the solid particles and microorganisms from the fluid by depositing them on the filters septum is what filter permeability does. A study of the correlation of the air permeability of the filter paper and rate of filtration is studied to get the active relationship and speed of the filtration. Through filter permeability process, the resistance is understood. Lower the permeability represents a high resistance and higher the permeability states a low resistance.. How Is Filter Permeability Expressed?. ...
A methodology to test the possible deviations of fracture relative permeabilities from straight-line relationship with saturation is discussed. It is shown that with matrix relative permeability data known, it is possible to obtain fracture relative permeabilities by history matching experimental data with double porosity numerical models output. Rather than linear saturation dependence, fracture relative permeability is a power law function of the corresponding phase saturation. The impact of several important parameters like double porosity formulation, capillary pressure and shape factor is discussed. It has been found that double porosity formulations (other than the double permeability model) could represent the flow in a fractured medium. (C) 2001 Published by Elsevier Science B.V ...
Read A Quantitative Model for the Dependence of Solute Permeability on Peptide and Cholesterol Content in Biomembranes, The Journal of Membrane Biology on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
In vivo and ex vivo studies with whole vessels demonstrated that the endothelium comprises the major permeability barrier in the blood vessel wall. As a lining between the blood and the underlying tissue, the endothelium is exposed to biochemical components of the blood and wall shear stress. The endothelium responds to these biochemical and mechanical agonists both metabolically and morphologically. Using a model system consisting of human umbilical vein endothelial cells cultured on a permeable polycarbonate membrane, the permeability barrier function of endothelial monolayers was characterized quantitatively by determination of permeability coefficients. The effect of biochemical agonists and wall shear stress on permeability was assessed by the extent to which the agonists modulated the baseline permeability coefficient. Permeability increased nearly 10-fold over baseline values in the presence of 0.1 U/ml thrombin. Using altered forms of thrombin, it was shown that both proteolytic activity ...
Phyllite clays are applied as a layer on a surface to be waterproofed and subsequently compacted. For this purpose, phyllite clays deposits can be grouped by their chemical and mineralogical characteristics, and these characteristics can be connected with their properties, mainly permeability, in order to select those deposits with the lowest permeability values. Several deposits of phyllite clays in the provinces of Almería and Granada (SE Spain) have been studied. The results of applying a multivariate statistical analysis (MVA) to the chemical data analysed from 52 samples determined by XRF, mineralogical analysis by XRD and permeability are reported. Permeability, a characteristic physical property of phyllite clays, was calculated using the results for experimental nitrogen gas adsorption and nitrogen adsorption-desorption permeability dependence. According to the results, permeability values differentiated two groups, i.e. group 1 and group 2, with two subgroups in the latter. The ...
The objective of this research is to develop and test a new concept for predicting permeability from routine rock properties. First, we develop a model predicting permeability as a function of capillary pressure. Our model, which is based on the work by Purcell, Burdine and Wyllie and Gardner models, is given by: (Equation 1 - See PDF) Combining the previous equation and the Brooks and Corey model for capillary pressure, we obtain: (Equation 2 - See PDF) The correlation given by this equation could yield permeability from capillary pressure (and vice-versa). This model also has potential extensions to relative permeability (i.e., the Brooks and Corey relative permeability functions) - which should make correlations based on porosity, permeability, and irreducible saturation general tools for reservoir engineering problems where relative permeability data are not available. Our study is validated with a large range/variety of core samples in order to provide a representative data sample over ...
The novel findings in this study are that an increase in gut apoptotic activity occurs after endotoxin infusion and is associated with increased gut macromolecular permeability and increased pulmonary cytokine expression. In this setting, the cointervention of feeding decreases the extent of apoptotic activity, gut permeability, and pulmonary cytokine expression. In other experimental settings, increased gut apoptosis results in increased gut permeability (38, 39). Further investigations suggest that increased gut permeability increases the systemic inflammatory response and involvement of distant organs (30). Together, our new results and previous observations suggest an important association between gut apoptosis, gut barrier function, and pulmonary inflammation during sepsis. Enteral feeding ameliorates increased gut apoptotic activity, which, we postulate, may be a key step in improving gut barrier function and decreasing inflammation in distant organs during sepsis.. Gut injury in sepsis ...
Introduction Relative permeabilities are factual data necessary to any prediction of reservoir production behavior. One important problem in determining relative permeabilities of porous media to gas is the effect of gas slippage on these determinat
Pelaksanaan hydraulic fracturing umumnya dilakukan pada reservoir yang memiliki karakteristik low permeability dan high skin yang menghasilkan laju produksi kecil. Metode stimulasi ini merupakan salah satu upaya untuk meningkatkan laju alir yang diperkirakan dapat meningkat dari produksi sebelumnya. Apabila dibandingkan pekerjaan hydraulic fracturing pada sumur low permeability dan moderate-high permeability dengan menggunakan persamaan Darcy maka peningkatan laju produksi pada suatu reservoir akan terlihat jelas. Perubahan paradigma dan strategi ini menjadi dasar untuk pelaksanaan pekerjaan hydraulic fracturing di struktur O. Sumur O-31 diproduksikan dari lapisan A yang merupakan formasi batu pasir (sandstone) dengan sementasi karbonat dari formasi Talang Akar. Berdasarkan hasil dari dari data log lapisan ini memiliki h = 6.4 m, K = 200 mD, resistivity = 11-26 ohm.m, Pr = 1266 psi, Sw = 35 %, porositas = 25, K = 20 mD, skin factor = + 4.6, dP = 443 psi. Pekerjaan hydraulic fracturing di sumur O-31
The following investigation focuses on the impact of capillary pressure on estimation of two phases relative permeability curves. Accurate relative permeability is a crucial parameter for evaluating reservoir performance. The unsteady state core flooding tests, which is considered in this study, is mostly used to measure oil-water relative permeabilities. The Johnson ,Bossler and Neumann (JBN) method is the conventional method for estimating relative permeabilities from field core. The limitations in the JBN method create an error in relative permeability curves and make it unrepresentative of a typical core flooding test results. There are always capillary pressure effects taking place during core flood tests. Ignoring of capillary pressure by JBN method will influence the calculation of relative permeability curves and final saturation levels. One dimensional numerical model with uniform initial saturation has been implemented in this study using Eclipse 100 software to understand the ...
The results show that a richer gut microbiota composition, a higher abundance of Faecalibacterium prausnitzii, a higher dietary intake of fibre and n-3 LCPUFA as well as multiple vitamins and minerals were associated with lower serum zonulin concentration, ie. lower intestinal permeability. Serum zonulin concentration correlated with serum endotoxin activity, markers of low grade inflammation and glucose metabolism in early pregnancy, suggesting that intestinal permeability may be of importance in regulating maternal metabolic health. Serum zonulin concentration increased with pregnancy progress. While Bifidobacterium animalis ssp. lactis 420 and n-3 LC-PUFA enhanced intestinal epithelium in vitro, they had no effect on serum zonulin levels during pregnancy ...
In the Part 1 paper (Gawin, et al. 2005) some experimental results concerning micro-structuralrntests, permeability measurements and stress-strain tests of four types of High Performance Concrete, exposed to elevated temperatures (up to 700oC) are presented and discussed. On the basis of these experimental results parameters of the constitutive relationships describing influence of damage and temperature upon material intrinsic permeability at high temperature were determined. In this paper the effects of various formulations of damage-permeability coupling on results of computer simulations are analysed and compared with the results obtained by means of the previously proposed approach, that does not take into account thernthermo-chemical concrete damage directly. Numerical solutions are obtained using the recently developedrnfully coupled model of hygro-thermal and damage phenomena in concrete at elevated temperatures. Highrntemperature effects are considered by means of temperature and ...
The aim of my thesis was to test whether an increase in the permeability of the gut is accompanied by an increase in the level of systemic lipopolysaccharides (LPS), also referred to as endotoxin. These two parameters were firstly concurrently determined in healthy women after the treatment with a single dose of aspirin which is thought to temporarily increase the paracellular permeability of the intestine. Gut permeability and the levels of systemic LPS in healthy women were then compared with those in women with Crohns disease (CD) as the latter are thought to have chronically elevated paracellular permeability of the gut. Both groups also ingested a high fat drink which is reported to results in the elevation of systemic LPS. In addition, faecal calprotectin, a biomarker of ongoing inflammation in the gut, and LPS-binding protein (LBP), a proposed indirect biomarker for the exposure to LPS in the systemic circulation, were determined both in healthy women and in those with CD. Data indicated ...
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This paper reports recent findings of a research programme focused on the carbonation and permeability of foamed concrete. The objective is to develop an environmentalfriendly and economical material for sustainable construction on peat. A four-year study showed that the rate of carbonation is related to the permeability, time and density. A water permeability test system has been developed based on ISO/DIS7031 and a draft standard prepared. They are aimed at promoting concrete durability research. It features a dual-test method for the measurement of water permeability with the standard 150 mm test cube prior to the determination of compressive strength. The calibration of the test system is by means of a mature test cube of known water permeability. The test system plays complementary role to the existing methods of assessing durability such as carbonation test and rapid chloride permeability. The test method is non-destructive, convenient and reliable for assessing concrete durability in the ...
Research activities will focus on permeability and impermeability as parameters to analyse changing European borders in an increasingly globalised world. This study will mainly be conducted from an economic perspective. First of all, the research will determine the role of borders in offering solutions to economic crises, either through an increased impermeability of states, or through new approaches to permeability within a changing international order. Secondly, we would like to look at borders via a costs and benefits analysis in order to assess the economic benefits of the dismantling of borders and the economic costs connected with functional borders. Thirdly, the research may ponder upon the permeability and impermeability of electronic frontier; the Internet may cross state borders, providing information globally, or attempts may be made to block this flow and introduce censorship, monitoring of citizens and protectionism. Finally, the research will summarise the practices and perception of the
Hydraulic fracturing of horizontal wells in unconventional reservoirs has become the dominant type of well completion performed in the United States. In very low permeability reservoirs (~.00001-.0001 mD), the wellbore is aligned with the minimum horizontal stress, and the completion includes multiple transverse fractures. These fractures may be placed with either open hole sleeve type completion systems (OHMS), or cased hole plug and perf systems (P-n-P). In slightly higher permeability reservoirs (1 to 10 mD) multiple longitudinal fractures have been found to be preferred to completions with transverse fractures. This study presents an evaluation of gas well productivity for both transverse and longitudinal fractured horizontal wells using CFD simulations. The first part of the work includes an evaluation of one and two transverse fractures, over reservoir permeability of 1, 10 and 100 mD. Results, given as fold of increase, are compared to the single transverse fracture model of Augustine (2011).
The study design includes three test days. During day 1, intestinal permeability at rest will be measured. When a blood samples is taken and urine is collected, subjects will ingest a sugar solution in the fasted state after which urine will be collected for 5 hours. In blood and urine, markers for intestinal permeability will be measured. Day 2 and 3 , the same study procedure will take place after the performance of an acute exercise load. The exercise will include a submaximal ergomtery test at 50% of their Wmax or an activity of daily living (ADL) test. The ADL test exist of a combination of several daily activities ...
Abstract. The intestinal epithelium, the largest interface between the host and environment, regulates fluxes of ions and nutrients and limits host contact with the massive load of luminal antigens. Local protective and tolerogenic immune responses toward luminal content depend on antigen sampling by the gut epithelial layer. Whether, and how exaggerated, the entrance of antigenic macromolecules across the gut epithelium might initiate and/or perpetuate chronic inflammation as well as the respective contribution of paracellular and transcellular permeability remains a matter of debate. To this extent, experimental studies involving the in vivo assessment of intestinal permeability using small inert molecules do not necessarily correlate with the uptake of larger dietary antigens. This review analyzes both the structural and functional aspects of intestinal permeability with special emphasis on antigen handling in healthy and diseased states and consequences on local immune responses to food ...
In typical permeability experiments, a disk sample is sealed gas tight over a support tube. A gas or gas mixture is supplied to one side, and one or more species permeate to the other side, where a sweep gas and/or pump collect the gas. The modes of operation are numerous, and so are the ways to analyze the permeation, including gas chromatography (GC) and mass spectroscopy (MS). Typically, an inert gas added to the entry side gas mixture is used for monitoring the presence or absence of background leakage through seal leaks or sample cracks and porosity.. In general, a large sample area or tubular sample is preferable, as it reduces the relative effects of leakage from seal ring and general equipment. It also simplifies the considerations of sample geometry for samples where the thickness is not much smaller than the diameter so that permeation from the side is significant. However, a large sample may put higher requirements to the mechanical assembly and seal.. These articles refer to ...
A permeability meter is available to help companies overcome the problem of specifying seals to prevent damage caused by water vapour
Nevertheless, these factors interplay with the neuroendocrine network, gut-associated lymphoid tissue, intestinal barrier, and eventually, the integrity of tight junctions between the epithelial cells. Eventually, the correct function of these factors will control and promote a balanced immune response.. Did you know most common chronic diseases are associated with an autoimmune response? Chronic inflammatory diseases like diabetes mellitus type II, inflammatory bowel disease, multiple sclerosis, gestational diabetes, and hyperlipidemia, to name a few. Therefore, if we are going to deal with autoimmune diseases, then why not treat the predecessor of this mechanism? Treat the gut, improve intestinal permeability = healthy patient.. Why treat the gut if the patient came in with a metabolic disease? The intestinal barrier has a crucial function; it regulates macromolecules traffic from food to protect the host. Inflammation is the first stage of every disease, and increased intestinal permeability ...
It is observed that low permeability reservoir characteristics and controlling factors are unclear in Triassic Yanchang formation in Ordos Basin Jiyuan region.In response to this issue,resolution sequence stratigraphy,se
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MEMOIRES: Hydrogeology of Rocks of Low Permeability. Shlomo P. Neuman and a great selection of similar Used, New and Collectible Books available now at
Scott Richard Fidler (1998). Spatial and temporal variability of hydraulic response in fractured, low permeability sediments. UWSpace. ...
The permeability of one of the first and second shield layers in a read head is greater than the permeability of the other of the first and second shield layers for providing a net image current field HIM which can be employed for counterbalancing other fields acting on a free layer structure in a spin valve sensor such as a sense current field HI in either a top or bottom single spin valve sensor or a net ferromagnetic coupling field HFC alone or in combination with a demagnetizing field HD in a dual spin valve sensor. Preferred high permeability materials are nickel iron or nickel iron alloys excluding cobalt and low permeability materials are cobalt based.
The KES-F8 Air Permeability Tester is designed to quickly and accurately measure the breathability and permeability of a wide range of samples, from those with high permeability, such as stockings, to those with low permeability, such as synthetic leather.. ...
A Mechanistic Framework for the In Silico Prediction of Regional Passive Gut Wall Permeability and its Inter-individual Variability in Humans ...
These methods are sensitive to two different types of signals: electric signals and water-soil pressure disturbances, respectively. The advantages of the SP technique lie in the high rate of data acquisition,which allows assessment of long dykes, and direct diagnosis in terms of leakage area delimitation and quantification. Coupled with punctual hydro-acoustic cartography, a leakage position can be precisely located, therefore allowing specific remediation decisions with regard to the results of the geophysical investigation. Here, the precise localization of leakage from an earth dyke has been identified using SP and hydro-acoustic signals, with the permeability of the preferential fluid flow area estimated by forward SP modeling. Moreover, we propose a general abacus diagram for the estimation of hydraulic permeability of dyke leakage according to the magnitude of over water SP anomalies and the associated uncertainty. ...
At Versaperm we employ a wide and growing range of sensors that are based on fundamentally different and divergent physical principals. The choice of the right sensor for an application is often critical in the successful deployment of the equipment. The matching of sensors to applications is a significant strategic advantages for our company.. Sensor types - click for more information on any sensor type. Universal sensors: mass spectrometer, gas chromatography, pressure measurements and semiconductor ...
Crohns disease and ulcerative colitis, collectively called inflammatory bowel disease (IBD), are immune-mediated conditions characterized by a chronic inflammation of the gut. Increased intestinal permeability has been shown to play a central role in the pathogenesis of IBD. What are the mechanisms by which intestinal permeability contributes to the pathophysiology of disease, and what can clinicians do about it?. Dietary changes, chronic alcohol consumption, stress, the use of antibiotics, and other environmental factors, as well as genetic factors, can lead to alterations in the gut microbiota, which in turn may induce intestinal inflammation and increase intestinal permeability. As clinicians, how can we help patients with dysbiotic microbiota?. Read More ...
Mitochondrial Permeability Transition (MPT) is reported as the mechanism of acetaminophen induced hepatic damage, however, rat models are resistant to acetaminophen induced toxicity. The occurrence and degree of mitochondrial permeability transition after treatment with 400 mg kgG1 of acetaminophen in albino Wistar rats were assessed. Animals were randomly distributed into seven groups; control, 12, 24, 36, 48, 60 and 72 h based on varying time (in hour) post acetaminophen prior to sacrifice after treatment. Mitochondrial Membrane Permeability Transition (MMPT) pore opening and mitochondrial cytochrome c release were estimated. Opening of MMPT pore and cytochrome c release were observed in 12, 24, 36 and 72 h, when compared with the control group. Liver function and histological results indicated no liver damage. It is concluded that toxic dose of acetaminophen induced mitochondrial permeability transition in rat hepatic tissues without leading to necrotic damage suggesting that rat hepatic ...
A memory device is provided with a structure for improved transmission line operation on integrated circuits. The structure for transmission line operation includes a first layer of electrically conductive material on a substrate. A first layer of insulating material is formed on the first layer of the electrically conductive material. A number of high permeability metal lines are formed on the first layer of insulating material. The number of high permeability metal lines includes composite hexaferrite films. A number of transmission lines is formed on the first layer of insulating material and between and parallel with the number of high permeability metal lines. A second layer of insulating material is formed on the transmission lines and the high permeability metal lines. The structure for transmission line operation includes a second layer of electrically conductive material on the second layer of insulating material.
OBJECTIVES: Chronic liver disease (CLD) is associated with both alterations of the stool microbiota and increased small intestinal permeability. However, little is known about the role of the small intestinal mucosa-associated microbiota (MAM) in CLD. The aim of this study was to evaluate the relationship between the duodenal MAM and both small intestinal permeability and liver disease severity in CLD. METHODS: Subjects with CLD and a disease-free control group undergoing routine endoscopy underwent duodenal biopsy to assess duodenal MAM by 16S rRNA gene sequencing. Small intestinal permeability was assessed by a dual sugar (lactulose: rhamnose) assay. Other assessments included transient elastography, endotoxemia, serum markers of hepatic inflammation, dietary intake, and anthropometric measurements. RESULTS: Forty-six subjects (35 with CLD and 11 controls) were assessed. In subjects with CLD, the composition (P = 0.02) and diversity (P , 0.01) of the duodenal MAM differed to controls. ...
TY - JOUR. T1 - The mitochondrial permeability transition from in vitro artifact to disease target. AU - Bernardi, Paolo. AU - Krauskopf, Alexandra. AU - Basso, Emy. AU - Petronilli, Valeria. AU - Blalchy-Dyson, Elizabeth. AU - Di Lisa, Fabio. AU - Forte, Michael. PY - 2006/5. Y1 - 2006/5. N2 - The mitochondrial permeability transition pore is a high conductance channel whose opening leads to an increase of mitochondrial inner membrane permeability to solutes with molecular masses up to ≈1500 Da. In this review we trace the rise of the permeability transition pore from the status of in vitro artifact to that of effector mechanism of cell death. We then cover recent results based on genetic inactivation of putative permeability transition pore components, and discuss their meaning for our understanding of pore structure. Finally, we discuss evidence indicating that the permeability transition pore plays a role in pathophysiology, with specific emphasis on in vivo models of disease.. AB - The ...
TY - JOUR. T1 - The mitochondrial permeability transition from yeast to mammals. AU - Azzolin, Luca. AU - von Stockum, Sophia. AU - Basso, Emy. AU - Petronilli, Valeria. AU - Forte, Michael A.. AU - Bernardi, Paolo. PY - 2010/6. Y1 - 2010/6. N2 - Regulated permeability changes have been detected in mitochondria across species. We review here their key features, with the goal of assessing whether a permeability transition similar to that observed in higher eukaryotes is present in other species. The recent discoveries (i) that treatment with cyclosporin A (CsA) unmasks an inhibitory site for inorganic phosphate (Pi) [Basso, E., Petronilli, V., Forte, M.A. and Bernardi, P. (2008) Phosphate is essential for inhibition of the mitochondrial permeability transition pore by cyclosporin A and by cyclophilin D ablation. J. Biol. Chem. 283, 26307-26311], the classical inhibitor of the permeability transition of yeast and (ii) that under proper experimental conditions a matrix Ca2+-dependence can be ...
TY - JOUR. T1 - Oxygen permeability and stability of Al2O3-doped SrCo0.8Fe0.2O3-δ mixed conducting oxides. AU - Wu, Zhentao. AU - Jin, Wanqin. AU - Xu, Nanping. PY - 2006/8/1. Y1 - 2006/8/1. N2 - A new series of Al2O3-doped SrCo0.8Fe0.2O3-δ (SCFA) mixed conducting oxides were synthesized by the conventional solid-state reaction method. Effects of doping Al2O3 (1, 3, 5 and 10 wt.%, respectively) on the crystal structure, order-disorder phase transition, microstructure, oxygen permeability and structure stability of SrCo0.8Fe0.2O3-δ (SCF) were investigated by XRD, TG-DSC, SEM, oxygen permeation measurement and the partial oxidation of methane (POM) to syngas reaction. Although the oxygen permeability of the SCF was weakened in the oxygen permeation measurement at the air/He gradient due to the doping of Al2O3, perovskite structure of SCFA was found stable in the low oxygen partial pressure (about 1.01325 × 102 Pa (10-3 atm)). In the POM reaction, the rate of the oxygen permeation of SCFA3 (the ...
Absolute Open Flow Potential (AOFP) is often the only productivity information available from low permeability gas formations particularly in the Appalachian Basin. Absolute Open Flow Potential (AOFP) is commonly evaluated through a single point test due to its cost effectiveness. In low permeability reservoirs, the time required for obtaining stabilized flow rate is often very long. Therefore, stabilized AOFP may not be achieved in short tests. Furthermore, most low permeability gas wells are hydraulically fractured to improve their productivity. Therefore, the post-fracture measured AOFP could be significantly influenced by fracture properties.;The objective of this was to develop a methodology to estimate formation properties from AOFP. Conventional methods for pressure transient analysis or deliverability testing analysis cannot be used since they require multiple pressure and rate data. To achieve the objective, the impact of formation properties on AOFP was studied. Several different solutions
Previous studies indicated that the micro integral membrane protein located within the media place of the integral membrane protein of Lactobacillus plantarum CGMCC 1258 had protective effects against the intestinal epithelial injury. In our study, we mean to establish micro integral membrane protein -knockout Lactobacillus plantarum (LPKM) to investigate the change of its protective effects and verify the role of micro integral membrane protein on protection of normal intestinal barrier function. Binding assay and intestinal permeability were performed to verify the protective effects of micro integral membrane protein on intestinal permeability in vitro and in vivo. Molecular mechanism was also determined as the zonulin pathway. Clinical data were also collected for further verification of relationship between zonulin level and postoperative septicemia. LPKM got decreased inhibition of EPEC adhesion to NCM460 cells. LPKM had lower ability to alleviate the decrease of intestinal permeability induced by
Previous studies indicated that the micro integral membrane protein located within the media place of the integral membrane protein of Lactobacillus plantarum CGMCC 1258 had protective effects against the intestinal epithelial injury. In our study, we mean to establish micro integral membrane protein -knockout Lactobacillus plantarum (LPKM) to investigate the change of its protective effects and verify the role of micro integral membrane protein on protection of normal intestinal barrier function. Binding assay and intestinal permeability were performed to verify the protective effects of micro integral membrane protein on intestinal permeability in vitro and in vivo. Molecular mechanism was also determined as the zonulin pathway. Clinical data were also collected for further verification of relationship between zonulin level and postoperative septicemia. LPKM got decreased inhibition of EPEC adhesion to NCM460 cells. LPKM had lower ability to alleviate the decrease of intestinal permeability induced by
Here, we advanced a novel technique using capillary ultrafiltration (CUF) probes to collect in vivo secreted proteins in the subcutaneous tissue of mouse ear. We fabricated two kinds of CUF probe, one with and one without a semi-permeable membrane hollow fiber. Proteins collected by CUF probes were profiled and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MADLI-TOF-MS) and quadrupole time-of-flight tandem mass spectrometry (Q-TOF-MS/MS) without using two-dimensional gel electrophoresis (2-DE) separation. Five proteins including cofilin-1, futuin-A, complement C3, gelsolin, and apolipoprotein C-1 were identified from the sample collected by the CUF probe with a semi-permeable membrane hollow fiber. The presence of well documented secretory proteins supports the efficiency of CUF probes in sampling in vivo secreted proteins. We also found that hemoglobin collected by the CUF probe without a semi-permeable membrane hollow fiber completely masked ...
Conjunctiva occupies most of the ocular surface area, and conjunctival permeability affects ocular and systemic drug absorption of topical ocular medications. Therefore, the aim of this study was to obtain a computational in silico model for structure-based prediction of conjunctival drug permeability. This was done by employing cassette dosing and quantitative structure-property relationship (QSPR) approach. Permeability studies were performed ex vivo across fresh porcine conjunctiva and simultaneous dosing of a cassette mixture composed of 32 clinically relevant drug molecules with wide chemical space. The apparent permeability values were obtained using drug concentrations that were quantified with liquid chromatography tandem-mass spectrometry. The experimental data were utilized for building a QSPR model for conjunctival permeability predictions. The conjunctival permeability values presented a 17-fold range (0.63-10.74 × 10−6 cm/s). The final QSPR had a Q2 value of 0.62 and predicted ...
Versaperm has launched a mass spectrometer version of its successful vapour permeability measurement system which works across every gas or group of gasses. Click to read more...
BACKGROUND: Intestinal permeability and adipose tissue inflammation are considered mechanistic links in the relationship between diet, obesity, and chronic disease. However, methods to measure both are not well standardized, and the reliability of commonly used measures is not known. METHODS: We calculated the intraclass correlation coefficient (ICC) for several common measures of intestinal permeability and adipose tissue inflammation from a randomized clinical trial of cross-over design in which normal weight (n=12) or overweight/obese (n=12) individuals each completed three 8-day dietary intervention periods. RESULTS: For biomarkers of intestinal permeability, plasma zonulin and lipopolysaccharide binding protein, ICCs were excellent (i.e., , 0.9). The direct measure of intestinal permeability, the lactulose/mannitol test, exhibited fair reliability (ICC=0.53). A wider range of ICCs (0.6-0.9), suggesting good to excellent reliability, were obtained for measures of adipose tissue ...
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A disulphimide group-containing acrylonitrile copolymer semi-permeable membrane which comprises:(A) from 99 to 50% by weight of acrylonitrile units;(B) from 1 to 50% by weight of units of an acrylonitrile-copolymerizable ethylenically unsaturated monomer containing one or two disulphimide groups; and(C) from 0 to 30% by weight of units of one or more other acrylonitrile-copolymerizable olefinically unsaturated monomer, the sum of the percentages amounts to 100.The semi-permeable membranes may be used in reverse osmosis and ultrafiltration.
TY - JOUR. T1 - Ammonia neurotoxicity. T2 - Role of the mitochondrial permeability transition. AU - Rama Rao, K. V.. AU - Jayakumar, A. R.. AU - Norenberg, M. D.. PY - 2003/6/1. Y1 - 2003/6/1. N2 - Hepatic encephalopathy (HE) is an important cause of morbidity and mortality in patients with severe liver disease. Although the mechanisms responsible for HE remain elusive, ammonia is generally considered to be involved in its pathogenesis, and astrocytes are thought to be the principal target of ammonia neurotoxicity. Altered bioenergetics and oxidative stress are also thought to play a major role in this disorder. In this paper, we present data invoking the mitochondrial permeability transition (MPT) as a factor in the pathogenesis of HE/hyperammonemia. The MPT is a Ca2+-dependent, cyclosporin A (CsA) sensitive process due to the opening of a pore in the inner mitochondrial membrane that leads to a collapse of ionic gradients and ultimately to mitochondrial dysfunction. Many of the factors that ...
Background and aim: Persistent stress and life events affect the course of ulcerative colitis (UC) by largely unknown mechanisms. Regulation of epithelial permeability to antigens is crucial for the balance between inflammation and immuno-surveillance, and increased intestinal permeability has been shown in patients with ulcerative colitis. Corticotropin releasing hormone (CRH) has been implicated as an important mediator of stress-induced abnormalities in intestinal mucosal function in animal models. Further cholinergic signalling during stress. has been reported to increase bowel ion secretion in humans and uptake of HRP in rodents via activation of mast cells.. The overall aim of this thesis was to examine the role of CRH-mediated and cholinergic signalling, and their interaction with mast cells and eosinophils, in the regulation of the mucosal barrier function in the normal human colon and in UC. In vivo studies or the use of surgical specimens for such studies have major shortcomings. ...
K. Ward, I. Bjarnason, P. Smethurst, T.J. Peters; Sequential Measurements of Small Intestinal Permeability in Chronic Alcoholics. Clin Sci (Lond) 1 February 1984; 66 (2): 63P. doi: Download citation file:. ...
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Epithelial damage caused by intestinal permeation enhancers is a source of debate over their safety. The medium chain fatty acid, sodium caprate (C10), causes reversible membrane perturbation at high dose levels required for efficacy in vivo, so the aim was to model it in vitro. Exposure of Caco-2 monolayers to 8.5mM C10 for 60min followed by incubation in fresh buffer led to (i) recovery in epithelial permeability (i.e. transepithelial electrical resistance (TEER) and apparent permeability coefficient (Papp) of [(14)C]-mannitol), (ii) recovery of cell viability parameters (monolayer morphology, plasma membrane potential, mitochondrial membrane potential, and intracellular calcium) and (iii) reduction in mRNA expression associated with inflammation (IL-8). Pre-incubation of monolayers with a mucosal prostaglandin cytoprotectant was attempted in order to further decipher the mechanism of C10. Misoprostol (100nM), inhibited C10-induced changes in monolayer parameters, an effect that was partially ...
Prediction of blood-brain barrier permeability of organic compounds / A. S. Dyabina, E. V. Radchenko, V. A. Palyulin, N. S. Zefirov // Doklady Biochemistry and Biophysics. - 2016. - Vol. 470, no. 1. - P. 371-374. Using fragmental descriptors and artificial neural networks, a predictive model of the relationship between the structure of organic compounds and their blood-brain barrier permeability was constructed and the structural factors affecting the readiness of this penetration were analyzed. This model (N = 529, Q2 = 0.82, RMSEcv = 0.32) surpasses the previously published models in terms of the prediction accuracy and the applicability domain and can be used for the optimization of the pharmacokinetic parameters during drug development. [ DOI ...
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1.Previous studies have indicated that the permeability of polyethyleneglycol across the human intestine is anomalously high in comparison with the permeability of sugars with similar molecular mass. In consequence it has been proposed that two or more distinct mechanisms must exist for the translocation of these classes of molecule or, alternatively, that the molecular parameter determining rate of penetration is each molecules minimum molecular dimension.. 2.The notional hydrogen-bonding capacity of a molecule correlates well with oil-water partition coefficient and also, in a variety of experimental systems, with rate of passive diffusion across biological membranes. A molecules hydrogen-bonding capacity is calculated by inspecting the structural formula and summing the individual theory-derived hydrogen-bonding capacities of the molecules functional groups.. 3.A classic set of intestinal permeability data that includes several ethyleneglycol oligomers and several sugars is re-analysed. A ...
Permeability is the property of rocks that is an indication of the ability for fluids (gas or liquid) to flow through rocks. High permeability will allow fluids to move rapidly through rocks. Permeability is affected by the pressure in a rock. The unit of measure is called the darcy, named after Henry Darcy (1803-1858). Sandstones may vary in permeability from less than one to over 50,000 millidarcys (md). Permeabilities are more commonly in the range of tens to hundreds of millidarcies. A rock with 25% porosity and a permeability of 1 md will not yield a significant flow of water. Such tight rocks are usually artificially stimulated (fractured or acidized) to create permeability and yield a flow.. ...
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To ensure the effective long-term storage of CO2 in candidate geological storage sites, evaluation of potential leakage pathways to the surface should be undertaken. Here we use a series of natural CO2 seeps along a fault in South Africa to assess the controls on CO2 leakage to the surface. Geological mapping and detailed photogrammetry reveals extensive fracturing along the mapped fault trace. Measurements of gas flux and CO2 concentration across the fracture corridor give maximum soil gas measurements of 27% CO2 concentration and a flux of 191 g m−2 d−1. These measurements along with observations of gas bubbles in streams and travertine cones attest to CO2 migration to the surface. Permeability measurements on the host rock units show that the tillite should act as an impermeable seal to upward CO2 migration. The combined permeability and fracture mapping data indicate that fracture permeability creates the likely pathway for CO2 migration through the low permeability tillite to the ...
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This is the first report of the immunohistological features of resolution of acute Campylobacterenterocolitis, and the first to report the striking increase in EC numbers and changes in macrophages and T lymphocytes which, in at least some patients, can persist for more than a year. This description is particularly important because similar changes were found in outpatients with prolonged IBS symptoms following acute bacterial enteritis. The persistence of these changes and their detection in symptomatic outpatients supports our hypothesis that the changes we have described following bacterial enteritis are in part responsible for the persistent symptoms commonly seen in clinical practice. This cohort study required a rather arduous protocol, with patients undergoing three rectal biopsies and two determinations of gut permeability. Although 47 patients agreed to participate, only 21 completed the three visits. However, as shown in table 1, those who did were demographically similar to those who ...
TY - JOUR. T1 - β-Sheet breaker peptide inhibitor of Alzheimers amyloidogenesis with increased blood-brain barrier permeability and resistance to proteolytic degradation in plasma. AU - Poduslo, Joseph F.. AU - Curran, Geoffry L.. AU - Kumar, Asok. AU - Frangione, Blas. AU - Soto, Claudio. PY - 1999/6/5. Y1 - 1999/6/5. N2 - Short synthetic peptides homologous to the central region of Aβ but bearing proline residues as β-sheet blockers have been shown in vitro to bind to Aβ with high affinity, partially inhibit Aβ fibrillogenesis, and redissolve preformed fibrils. While short peptides have been used extensively as therapeutic drugs in medicine, two important problems associated with their use in central nervous system diseases have to be addressed: (a) rapid proteolytic degradation in plasma, and (b) poor blood-brain barrier (BBB) permeability. Recently, we have demonstrated that the covalent modification of proteins with the naturally occurring polyamines significantly increases their ...
TY - JOUR. T1 - Permeability decay in CAVH hemofilters. AU - Jenkins, R. D.. AU - Kuhn, R. J.. AU - Funk, J. E.. PY - 1988. Y1 - 1988. N2 - Change in hydraulic permeability over time was measured in four types of continuous arteriovenous hemofiltration (CAVH) hemofilters in order to characterize permeability decay and demonstrate that permeability decay occurs without membrane protein exposure. Polyamide, polysulfone, and polyacrylonitrile membrane hemofilters were placed in a gravity-driven in vitro CAVH apparatus. Distilled and deionized water or saline was used to perfuse the hemofilters. A biphasic pattern of permeability decay was seen in all hemofilter types. A large exponential decline in permeability occurred over the first 1 to 6 hours, with a more gradual decay thereafter. Of all membranes studied, polysulfone hemofilters were the most permeable upon initiation of use but showed the most pronounced early and late permeability decay. Both polyamide and polyacrylonitrile hemofilters ...
Selective Permeability - What is it? Selective permeability means that the cell membrane has some control over what can cross it, so that only certain molecules either enter or leave the cell.
Early age cracking of bridge decks is a national problem, and may substantially reduce service lives and increase maintenance costs. Cracking occurs when the tensile stress exceeds the tensile strength of the concrete. This is a time-dependent phenomenon, since both the stress and strength change at early ages. Moisture loss increases stress (with increasing shrinkage) and impairs strength gain. Internal curing is one method that has been suggested to reduce early age bridge deck cracking, particularly of concretes with low water to cementitious materials (w/cm) ratios. Many state highway agencies have implemented high performance concrete (HPC) for bridge decks. The low permeability of HPC is used to protect reinforcing steel and prevent corrosion. However, if the concrete cracks, then the protection may be greatly diminished. Transverse cracks due to concrete shrinkage allow water and corrosive chemicals to quickly reach the reinforcing steel causing corrosion and shortening the lifespan of ...
purpose. To investigate the relationship between scleral permeability and nonenzymatic cross-link density.. methods. Scleral discs 18 mm in diameter were dissected from the medial and lateral equatorial regions of 60 cadaveric porcine eyes. Samples were incubated for 24 hours with control solution or methylglyoxal at concentrations of 0.001%, 0.01%, 0.10%, and 1.00%. Nonenzymatic cross-link density in treated and control groups was quantified with the use of papain digest and fluorescence spectrophotometry. Treated scleral discs were mounted in a customized Ussing-type chamber connected to vertical tubing, and specific hydraulic conductivity was determined according to the descent of a column of degassed saline at room temperature. Permeability to diffusion of fluorescein in a static chamber was determined for another set of treated scleral samples.. results. Methylglyoxal treatment effectively increased nonenzymatic cross-link content, as indicated by the average fluorescence for each group. ...
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When there is damage to the intestinal lining it can open up slightly and this allows larger particles, such as undigested or partially digested foods and bacteria, to enter into the bloodstream. This leads to malabsorption of nutrients as they pass through into the blood stream in a form that the body cannot use and it can also lead to excessive absorption of bacteria and other molecules that the intestines usually prevent from entering the blood stream.. The immune system is not used to these particles and sees them as foreign and you can develop food sensitivities and candida infections as a result. This can lead to inflammation, irritation and allergic like reactions. Both malabsorption and increased intestinal permeability (leaky gut) are associated with chronic gastrointestinal imbalances as well as many systemic disorders.. The Cyrex Array 2….Intestinal Antigenic Permeability Screen™, identifies an immune response indicating damage to the intestinal mucosal microstructures, ...
Mitochondria play an important role in energy production, Ca2+ homeostasis and cell death. In recent years, the role of the mitochondria in apoptotic and necrotic cell death has attracted much attention. In apoptosis and necrosis, the mitochondrial permeability transition (mPT), which leads to disru …
Aguilera, R.. Relative Permeability Concepts for Predicting the Performance of Naturally Fractured. Reservoirs. JCan PetT,.22,41, (1982). Amaefule, J.O. and Handy, L.I., The Effect oflnterfacial Tensions on Relative Oil/Water Permeabilities of Consolidated Porous Media. Soc Pet E J, 371, (1982). Bardon, C. and Longeron, D., Influence of Very Low Interfacial Tensions on Relative Permeability. Soc Pet EJ, 20, 391,(1980). Batycky, J.P., Mirkin, M.I., Besserer, G.J., Jackson, C.H., Miscible and Immiscible Displacement Studies on Carbonate Reservoir Cores. JCanPetT,2L, 104,(1981A). Batycky, J.P., McCaffery, F.G., Hodgins, P.K., Fisher, D.B., Interpreting Relative Permeability and. Wettability from Unsteady-State Displacement Measurements. Soc Pet E J, 21, 296, (198IB). Bemsten, R.G., Using Parameter Estimation Techniques to Convert Centrifuge Data into a Capillary. Pressure Curve. SPE paper 5026 presented at the SPE-AIME 49th Annual Meeting, Houston, Texas, (Oct. 6-9 1974). Broadbent, S.R. and ...
Mitochondrial dysfunction in heart failure includes greater susceptibility to mitochondrial permeability transition (MPT), which may worsen cardiac function and decrease survival. Treatment with a mixture of the n3 polyunsaturated fatty acids (n3 PUF
Looking for cell permeability? Find out information about cell permeability. The permitting or activating of the passage of substances into, out of, or through cells, or from one cell to another. These materials traverse either the... Explanation of cell permeability
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Gas shales and tight reservoirs exhibit extremely low permeability. This low permeability makes it difficult to apply traditional transport modeling approaches, such as Darcys law, to shales [9, 10]. Gas flow in organic matter, natural fractures, and hydraulic fractures occurs via different mechanisms: continuum flow, slip flow, and Knudsen diffusion. Adsorbed gas desorption from the organic matter also plays a role in gas transport [11]. It is challenging to develop a comprehensive model to describe the multiple mechanisms in the gas transport process.. S. Huang et al. proposed a comprehensive apparent permeability model to consider the multiple transport mechanisms in shale gas reservoirs. The specific mechanisms include viscous flow, slip flow, Knudsen diffusion, and surface diffusion. In their model, the pore diameter and mean free path of gas molecules are corrected by considering the adsorption layer and dense gas effect.. Y. Zeng et al. develop a modified apparent permeability model to ...
The permeability transition pore (PTP) is a mysterious structure that induces cell death by increasing the permeability of the inner mitochondrial membrane (IMM) to ions and soluble molecules. In 2015, the F1FO‐ATPase was identified as being involved in forming the PTP in eukaryotes [1]. Two hypotheses were put forward to explain the mechanism of PTP opening, both of which involve the mitochondrial F1FO‐ATPase: the channel forms within the c‐ring [2] or results from the conformational changes of F1FO‐ATPase dimers [3]. F1FO‐ATPase is a multisubunit enzyme at the cristae edges of the IMM that either synthesizes (forward reaction) or hydrolyses ATP (reverse reaction) in the catalytic hydrophilic F1 domain while translocating H+ through the c‐ring in the hydrophobic FO domain.. The first hypothesis by Alavian and colleagues proposes that the PTP channel is created within the c‐ring of the FO subunit by Ca2+‐dependent extrusion of the extrinsic F1 domain from the membrane‐embedded ...
Activation of the mitochondrial permeability transition pore (PTP) clearly plays a key role in some of the most wide-spread and therapeutically challenging huma...
Synchronization of our circadian rhythm, the small intestine circadian rhythm, and the microbial circadian rhythm causes a diurnal fluctuation of small intestinal permeability. Bacteria that strengthen the barrier bind to the epithelial cells that make up the lining of the small intestine. This increases expression of a protein called myosin heavy chain II(MHCII), which increases the presence of immune cells in the small intestine. These immune cells (CD4+ IL10+ IELs) secrete an anti-inflammatory cytokine (IL10), that regulates intestinal permeability and prevents excessive inflammation.. This causes variation of intestinal permeability where permeability is higher during the active period, but at the same time, tolerance is promoted. This means that even though permeability of the intestine is higher during our active/feeding period, immune cells in the gut put the brakes on inflammation.. Moreover, during the resting/fasting period, permeability of the small intestine is lower, but we are more ...
Polymer retention is one of the most important factors to govern polymer propagation through porous media, determining whether successful or not. The focus of previous studies has been limited to polymer concentration loss caused by the retention; not only change in polymer concentration, but also reduction in reservoir permeability is the main issue for theoretical transport study. Due to the lack of accuracy of Langmuir isotherm describing the polymer retention mechanisms, this study proposes a new type of matching interpretation method to correlate the permeability reduction factors from experiments to permeability. In order to solve the problem of poorly matching results between estimation and observation, use of nonadsorptive constant conditionally selected in matching process was made. Based on the threshold permeability reduction factors, approximate critical permeability can be calculated to which nonadsorptive constant would be applied. Results showed significant improvements in the ...
One thing we know from research is that even in people without an autoimmune/allergic reaction to gluten, consumption of gluten will trigger the release of a protein called zonulin.. The reason this is important is because zonulin increases intestinal permeability. In other words, there is an opening of the gap between the cells of the gut lining. It causes those shoe laces to remain open.. So…. EVERYONE who consumes gluten will experience an increase in intestinal permeability. Or to go by the more slang term you may have heard, leaky gut.. Proof that we all should avoid gluten? Not so fast!. Usually when we eat proteins we digest them by breaking them down into amino acids, which can then pass through the gut into the bloodstream. Intact proteins or large polypeptides (chains of joined amino acids) cannot do this.. But no human can digest gluten.. And so as gluten is an indigestible protein it should not be able to pass through the cells of our gut lining (more accurately, were referring ...
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Relative permeability is one of the key parameters governing fluid flow through porous media. Determination of relative permeability is traditionally conducted in the laboratory using either recombined reservoir oil or laboratory oil at simulated reservoir conditions, or simply at laboratory conditions. This is because it is expensive to sample representative uncontaminated reservoir fluids and extremely difficult to cut reservoir cores without altering their surface properties. Restoring rock properties to their original reservoir conditions has been a technical challenge to the industry. Upscaling laboratory special core-analysis data to reservoir scale is also a concern. Consequently, the industry has been researching new methods to extract relative permeability in situ, including the utilization of specially designed permanent downhole electric resistivity array, pressure and flow rate measurements. In this study, a different approach was taken. A semi-analytical model, developed to infer ...
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It is expressed in units of darcies (d). Permeability of 1 d allows the flow of 1 cm3 per second of fluid with 1 cP (centipoise ... "Permeability". AAPG. Retrieved 1 July 2019. "Shear strength". NPTEL. Retrieved 24 August 2015. Terzaghi, K., Peck, R.B. and ... Void ratio is mathematically related to the porosity by e = n 1 − n {\displaystyle e={\frac {n}{1-n}}} Permeability A measure ... Compaction is the process by which the density of soil is increased and permeability of soil is decreased. Fill placement work ...
Permeability decreases for 10 to 20 days possibly due to physical changes of the structure of the soil. Permeability increases ... permeability just continues to decrease. The change in permeability with time is observed in various field situations. ... Permeability decreases for 2 to 4 weeks due to disintegration of aggregates and biological clogging of soil pores with ... As the reservoir is not uniform in permeability, injected water tends to go through high permeable zone, and does not go ...
... vapour permeability etc." Poor lime is also known as lean or meager lime. Poor lime sets and cures very slowly and has weak ... vapor permeability; flexibility; and resistance to sulfates. These qualities are affected by many factors during each step of ...
Permeability tests". Retrieved 2019-04-07. Sjursen, Morten Andreas; Dyvik, Rune. "Lab Test - Oedometer Test ... Compressibility, permeability and durability tests - BSI British Standards". Retrieved 2019-04-07. "BS EN ... providing measurements of the coefficient of consolidation and the permeability of the soil. The word "oedometer" (/iˈdɒmɪtər/ ... 2019 covers various methods of soil permeability testing, including oedometer tests on saturated samples. An oedometer is ...
Four or five parameters are evaluated: A: Soil depth and texture; B: Soil permeability; C: Soil chemical characteristics; D: ...
In the second-season episode "The Financial Permeability", when Penny is short on money, Leonard pays for her share of a group ... This is seen in "The Financial Permeability", when she finds herself behind on her bills, and borrows money from Sheldon, only ... "The Financial Permeability". The Big Bang Theory. Season 2. Episode 14. February 2, 2009. CBS. "The Habitation Configuration". ...
Good oxygen permeability. Good ultra-violet resistance but poor resistance to acids and bases. Soluble in chloroform and other ...
... permeability (September 1885); permittance (now called capacitance) and permittivity (June 1887); reluctance (May 1888); ...
"The Financial Permeability". The Big Bang Theory. Season 2. Episode 14 (31). February 2, 2009. "The Classified Materials ... "The Financial Permeability" he made the sign of the cross - a Catholic practice - during an encounter with Kurt, Penny's former ...
Immediately after an earthquake, the fault zone can be damaged and have higher permeability, but heals within a few months. ... She became interested in the permeability of fractured rocks, demonstrating that seismic waves can unclog fractures. Brodsky ... Elkhoury, Jean E.; Brodsky, Emily E.; Agnew, Duncan C. (2006). "Seismic waves increase permeability". Nature. 441 (7097): 1135- ... finding a series of temperature pulses that occur due to the flow of fluids through a zone of increased permeability. ...
... is a non-SI unit of gas permeability (specifically, gas permeability) used in the membrane technology and contact lens ... The cm corresponds in the permeability equations to the thickness of the material whose permeability is being evaluated, the ... Permeance can be expressed as the ratio of the permeability with the thickness of membrane. 1 G P U = 10 − 6 c m S T P 3 c m 2 ... To convert to CGS permeability unit, one must use the following: 1 b a r r e r = M × 3.35 × 10 − 13 g ⋅ c m s ⋅ c m 2 ⋅ b a r ...
PMID 13642302.[permanent dead link] Payton, B. W.; Bennett, M. V. L.; Pappas, G. D. (December 1969). "Permeability and ... I. Modifications of surface membrane permeability". J. Cell Biol. 22 (3): 565-86. doi:10.1083/jcb.22.3.565. PMC 2106478. PMID ... Loewenstein WR (July 1966). "Permeability of membrane junctions". Ann. N. Y. Acad. Sci. 137 (2): 441-72. Bibcode:1966NYASA.137 ... "Effect of antipeptide antibodies directed against three domains of connexin43 on the gap junctional permeability of cultured ...
Editing alters Ca2+ permeability. Deficiency of vitamin B1 is correlated with alterations in editing of Glur2 pre-mRNA. ... editing of the Q/R site of Glur2 thereby increasing the level of unedited Glur2 resulting in increased calcium permeability of ...
Colton, C. K.; Smith, K. A.; Merrill, E. W.; Farrell, P. C. (1971). "Permeability studies with cellulosic membranes". Journal ...
This parallel artificial membrane permeability assay PAMPA technique measures the permeability across specifically formulated ... The anomalously large permeability of water through bilayers is still not completely understood and continues to be the subject ... This increase in permeability primarily affects transport of ions and other hydrated species, indicating that the mechanism is ... Chakrabarti AC (1994). "Permeability of membranes to amino acids and modified amino acids: mechanisms involved in translocation ...
Selective permeability to small cations". The Journal of General Physiology. 61 (6): 669-86. doi:10.1085/jgp.61.6.669. PMC ... This characteristic is called selective permeability. The archetypal channel pore is just one or two atoms wide at its ... Hille B (December 1971). "The permeability of the sodium channel to organic cations in myelinated nerve". The Journal of ... loop and two transmembrane helices was used as a model to study the permeability and the selectivity of ion channels in the ...
Hemorrhagic manifestations include vascular permeability. Upon entry, the Lassa mammarenavirus infects almost every tissue in ...
"Water permeability of human erythrocytes. Identification of membrane proteins involved in water transport". European Journal of ...
The major weakness of the lipid membrane was the lack of an explanation of the high permeability to water, so Nathansohn (1904 ... J F Danielli and H Davson."A contribution to the theory of permeability of thin films." Journal of Cellular and Comparative ... In 1941, Brooks & Brooks published a monograph The Permeability of Living Cells, which rejects the bulk phase theories. Jacques ... In 1889, Hamburger used hemolysis of erythrocytes to determine the permeability of various solutes. By measuring the time ...
Keminer, Oliver; Peters, Reiner (July 1999). "Permeability of Single Nuclear Pores". Biophysical Journal. 77 (1): 217-228. ... that the change of the permeability barrier of the NE was due to changes within the NPC and is what allows the entry of mitotic ... "Characterisation of the passive permeability barrier of nuclear pore complexes". The EMBO Journal. 28 (17): 2541-2553. doi: ...
... the permeability of organisational structures; and the inclusiveness of participation". Openness can be said to be the opposite ...
The permeability of residential neighborhoods, or accessibility to outside traffic, is another factor. The proximity of ... Gower.CS1 maint: multiple names: authors list (link) White, Garland F. (1990). "Neighborhood Permeability and Burglary Rates". ...
It also increases vascular permeability. LTD4 is released by basophils. Other leukotrienes that function in a similar manner ...
This formula assumes that the magnetic susceptibility is negligible, i.e. that μr ≈ 1 where μr is the magnetic permeability of ... μ0 is the vacuum permeability; ε0 is the vacuum permittivity. ...
... can interfere with the electron transport system, Ca2+ fluxes and membrane permeability. Also several experiments have ... Da Lozzo, EJ; Oliveira, MBM; Carnieri, EGS (1998). "Citrinin-induced mitochondrial permeability transition". J. Biochem. Mol. ...
In non-enveloped viruses, the membrane permeability changes may be sufficient to induce cell lysis, thereby permitting the new ... Gonzalez ME, Carrasco L (2005). "Viral proteins that enhance membrane permeability". In Fischer WB (ed.). Viral membrane ... Carrasco L (August 1995). "Modification of membrane permeability by animal viruses". Advances in Virus Research. 45: 61-112. ... Carrasco L, Otero MJ, Castrillo JL (1989). "Modification of membrane permeability by animal viruses". Pharmacology & ...
A vesiculo-vacuolar organelle (VVO) is an organelle that contributes to endothelial cell permeability. VVOs are found in the ... Dvorak, AM; Feng, D (April 2001). "The vesiculo-vacuolar organelle (VVO). A new endothelial cell permeability organelle". ... contributing to the increase in vascular permeability that occurs during the process of inflammation. This kind of transport is ...
This is thought to be due to its effect on intestinal permeability. In some developing countries Giardia is present in 30% of ... The result is increased intestinal permeability. There appears to be a further increase in programmed enterocyte cell death by ... increased intestinal permeability, and programmed cell death of small intestinal epithelial cells. Both trophozoites and cysts ... Giardia intestinalis, which further damages the intestinal barrier and increases permeability. There is significant ...
Permittivity is the dual of permeability. Electrostriction is the dual of magnetostriction. Piezoelectricity is the dual of ...
This gives EPS a higher permeability. EPS boards typically don't delaminate easily, but should be constructed using a vent to ...
... the permeability of soil for water Permeability (electromagnetism), the degree of magnetization of a material in response to a ... permeability of free space or magnetic constant, a physical constant, the value of magnetic permeability in a classical vacuum ... to transmit fluids Relative permeability, in multiphase flow in porous media Permeability (foundry sand), a test of the venting ... Permeability, permeable, and semipermeable may refer to: Semipermeable membrane, a membrane which will allow certain molecules ...
Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the capacity of ... An example of increased vascular permeability is in the initial lesion of periodontal disease, in which the gingival plexus ... Q J Exp Physiol Cms 59, 283-309 (1974). Bates, D. O. & Harper, S. J. Regulation of vascular permeability by vascular ... Estimation of apparent tumor vascular permeability from multiphoton fluorescence microscopic images of P22 rat sarcomas in vivo ...
is the ratio of the permeability of a specific medium to the permeability of free space μ0: μ. r. =. μ. μ. 0. ,. {\displaystyle ... Its relation to permeability is B. =. μ. H. {\displaystyle \mathbf {B} =\mu \mathbf {H} }. where the permeability, μ, is a ... Relative permeability and magnetic susceptibility [edit]. Relative permeability, denoted by the symbol μ. r. {\displaystyle \mu ... Permeability, μ (H/m) Relative permeability, max., μ/μ0 Magnetic field Frequency, max. ...
Published permeability coefficient ( Kp) data for the transport of a large group of compounds through mammalian epidermis were ... Variations in permeability of human skin and between specimens. Int. J. Pharm. 18:299-309 (1984).Google Scholar ... skin permeability partition coefficient molecular volume lipid lamellae stratum corneum This is a preview of subscription ... Solute structure-permeability relationships in human stratum corneum. J. Invest. Dermatol. 93:280-286 (1989).Google Scholar ...
Magnetic permeability, change in the resultant magnetic field inside a material compared with the magnetizing field in which ... The relative permeability μr is then defined as the ratio μ/μ0, which is dimensionless. Thus, the relative permeability of free ... Magnetic permeability μ (Greek mu) is thus defined as μ = B/H. Magnetic flux density B is a measure of the actual magnetic ... However, [μ0/4π × 10-7] is 1.00000000055, still very close to its former value.) In these systems the permeability, B/H, is ...
This chapter provides an overview of bilayer permeability and selectivity of permeabilization. Based on the hydrophobic nature ... Banfalvi G. (2016) Permeability of Membranes. In: Permeability of Biological Membranes. Springer, Cham. * First Online 11 ... The importance of permeability is underlined by the integrity of cell membrane in maintaining the viability of cells. Different ... To overcome the permeability barrier different transport processes have been evolved for crossing the cell membrane. Small ...
High membrane permeability for melatonin.. Yu H1, Dickson EJ1, Jung SR1, Koh DS2, Hille B3. ... Membrane permeabilities for uncharged species plotted against n-octanol/water partition coefficients for indoleamines and model ... Two dashed traces labeled 5 and 0.2 show the effect of increasing the assumed membrane permeability by 5 or decreasing it to ... In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could ...
... through consistent mitochondrial permeability transition pore opening results in mitochondrial dysfunction ... Inhibition of Mitochondrial Permeability Transition Pore Evaluated by Calcium Retention Capacity Assay. *Download Brochure ... Inhibition of Mitochondrial Permeability Transition Pore Evaluated by Calcium Retention Capacity Assay. News-Medical. 09 ... Inhibition of Mitochondrial Permeability Transition Pore Evaluated by Calcium Retention Capacity Assay. News-Medical, viewed 09 ...
Calcium permeability of ligand-gated channels.. Burnashev N1.. Author information. 1. Max-Planck-Institut für medizinische ... Many of them have different Ca2+ permeability providing immense diversity in Ca2+ entry mediated by ligand-gated channels ... The studies reviewed in this article provide information about known structural determinants of Ca2+ permeability of the ligand ... analysis of cloned channels allowed to identify structural elements in the pore forming regions determining Ca2+ permeability ...
Includes cutting-edge methods and protocols covering a variety of permeability barrier Provides step-by-step detail essential ... Permeability Barrier. Book Subtitle. Methods and Protocols. Editors. * Kursad Turksen Series Title. Methods in Molecular ... In Permeability Barrier: Methods and Protocols, a variety of experienced researchers contribute techniques to study this ... Authoritative and practical, Permeability Barrier: Methods and Protocols serves as an ideal guide for all scientists seeking to ...
Purchase Permeability Properties of Plastics and Elastomers - 3rd Edition. Print Book & E-Book. ISBN 9781437734690, ... Permeability Properties of Plastics and Elastomers 3rd Edition. 0.0 star rating Write a review ... Permeability properties are essential data for the selection of materials and design of products across a broad range of market ... This unique handbook brings together a wealth of permeability data in a form that enables quick like-for-like comparisons ...
Purchase Permeability Properties of Plastics and Elastomers - 4th Edition. Print Book & E-Book. ISBN 9780323508599, ... Permeability Properties of Plastics and Elastomers 4th Edition. 0.0 star rating Write a review ... Permeability Properties of Plastics and Elastomers, Fourth Edition provides a comprehensive collection of graphical multipoint ... Enables engineers to improve performance of their products where permeability properties are important, from where packages ...
Definition of capillary permeability factor. Provided by Stedmans medical dictionary and Includes medical terms and ...
Glomerular basement membrane: in vitro studies of water and protein permeability. Am. J. Physiol. 1992. 262:F919-F926. View ... For example, the diffusional permeability of GBM to an albumin-size molecule is less than 1% that of a layer of water of equal ... What determines glomerular capillary permeability?. William M. Deen Department of Chemical Engineering and Division of ... These findings, combined with data on the permeability of the basement membrane and evidence that the endothelium may be a more ...
The overall permeability of the laminate, , is a function of the thickness and of the permeabilities of the single layer :. ... The calculation of permeability constant for multilayered films is performed using the following relation [1]:. where is the ... is permeability of individual layer.. When vapour of water or organic molecules is used in the permeability measurements, the ... is indicated as permeability coefficient (or constant) or permeation coefficient or simply as permeability (. ). ...
... resulting in a reduction in the void ratio and associated permeability. Estimating the permeability distribution within the gob ... Variations of the permeability in the vertical direction are based on a model of caving and block rotation, which considers the ... The authors have developed a new methodology to determine both horizontal and vertical variations in the permeability of the ... The resulting three-dimensional permeability distribution in the gob is then transferred to a reservoir model. The paper ...
Landscape permeability is the degree of freedom with which animals can move through a landscape. There are a number of factors ... Landscape permeability is a term used by conservationists to refer to how freely animals can move through a landscape. It has ... But landscape permeability makes more sense particularly for things like birds. My city has several wild areas around it, but I ... Landscape permeability is definitely a better term than landscape corridor. I had heard of the need for corridors before, and ...
Conventional relative permeability, as well. as generalized relative permeability coefficients (with the viscous. coupling ... relationship between the conventional relative permeabilities and. the generalized relative permeability coefficients is ... Generalized relative permeability coefficients during steady-state two-phase flow in porous media, and correlation with the ...
... filler being present in an amount effective to reduce the ratio of the carbon dioxide permeability to the oxygen permeability ... A controlled permeability film including a film forming polymer and optionally including a dispersing polymer; and an inert ... Permeability Testing. The above films and two commercially available produce storage films were tested for oxygen permeability ... Effect of Different Types of Coating Material on CO2 /O2 Permeability Ratio. The permeability ratio can be changed by the ...
The porosity and permeability of the caved zone (gob) in a longwall operation impact many ventilation and methane control ... Mining Publication: Prediction of Porosity and Permeability of Caved Zone in Longwall Gobs. Keywords: Gases Gobs Longwall ... Thus, there has always been debate on the likely values of porosity and permeability of the caved zone and how these values can ... The results suggest that the gob porosity and permeability values can be predicted by this approach and the presented models ...
Hydrogeology of Rocks of Low Permeability. Shlomo P. Neuman and a great selection of similar Used, New and Collectible Books ... Hydrogeology Rocks Low Permeability. You Searched For: Title: hydrogeology rocks low permeability ... MEMOIRES: Hydrogeology of Rocks of Low Permeability, Two Volume Set, Volume XVII, Part 1: Proceedings; Part 2: Proceedings ...
Law 4521/2018, published in March 2018, provides for a 5% quota in higher education programmes for upper secondary vocational education (Epaggelmatiko Lykeio, EPAL) graduates. This quota is additional to the total number of non-VET students entering higher education programmes.
Capillary permeability factor definition at, a free online dictionary with pronunciation, synonyms and ...
High Permeability Magnetic Shielding Sheet 1380 has a soft magnetic sheet sandwiched between layers of polyester film with a ... 3M™ High Permeability Magnetic Shielding Sheet 1380 has a soft magnetic sheet sandwiched between layers of polyester film with ... High permeability material to provide excellent near-field magnetic shielding effectiveness for lower frequencies (. ... High permeability material to provide excellent near-field magnetic shielding effectiveness for lower frequencies (. ...
We provide permeability assays for small molecule formulations such as pharmaceuticals, industrial chemicals and consumer ... The Caco-2 permeability assay provides a measure of the permeability of a test compound across the intestinal barrier and its ... Apparent permeability rates (Papp). Experimental recovery. Click here to contact an expert today for your permeability testing ... Atenolol (low passive permeability). Metoprolol (high passive permeability). Analysis Method. LC-MS/MS quantification of test ...
Membrane permeability is the quality of a cells plasma membrane that allows substances to pass in and out of it. High membrane ... Permeability is largely dependent on the structure of the cell membrane, which is composed of two back-to-back layers of ... Membrane permeability is essentially the ability of certain substances to pass in and out of an organic or semi-organic barrier ... Permeability is an important feature because it facilitates continuous but controlled traffic in and out of the cell. As a ...
Absolute permeability (aka intrinsic or specific permeability)Edit. Absolute permeability denotes the permeability in a porous ... Tensor permeabilityEdit. To model permeability in anisotropic media, a permeability tensor is needed. Pressure can be applied ... PermeabilityEdit. Permeability is the property of rocks that is an indication of the ability for fluids (gas or liquid) to flow ... The SI unit for permeability is m2. A practical unit for permeability is the darcy (d), or more commonly the millidarcy (md) (1 ...
... was tested on red blood cells of rats and on black lipid membranes for changes of membrane permeability. In rat erythrocytes ... Properties of the leak permeability induced by a cytotoxic protein from Pseudomonas aeruginosa (PACT) in rat erythrocytes and ... The presence of cholesterol is a prerequisite for the occurrence of these PACT-induced permeability changes. © 1985. ... was tested on red blood cells of rats and on black lipid membranes for changes of membrane permeability. In rat erythrocytes ...
... R. Gholami,1 A. R. Shahraki,2 and M. Jamali ... R. Gholami, A. R. Shahraki, and M. Jamali Paghaleh, "Prediction of Hydrocarbon Reservoirs Permeability Using Support Vector ...
Abnormalities of red cell membrane cation permeability are seen in several hereditary disorders. These dominantly inherited ... encoded search term (Hereditary Disorders of Red Cell Permeability) and Hereditary Disorders of Red Cell Permeability What to ... Hereditary Disorders of Red Cell Permeability. Updated: Jan 30, 2019 * Author: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP; ... In contrast, the primary abnormality in DHSt is a change in the relative membrane permeability to K+. Efflux of K+ is increased ...
  • Although intestinal permeability is higher at birth in preterm than term infants, there is usually rapid maturation of the intestinal barrier over the first few days of life in both populations. (
  • The investigators hypothesize that increased levels of measures of intestinal permeability (serum zonulin, urine lactulose/rhamnose (LA/Rh), and fecal alpha1- antitrypsin will identify infants at high risk for NEC. (
  • The purpose of the study is to determine whether measurement of intestinal permeability in serum will correlate with other markers of intestinal barrier leakiness measured in urine (LA/Rh) and stool (alpha-1 antitrypsin. (
  • The determination of intestinal permeability remains a challenge. (
  • Intestinal permeability to intact lactose in newborns and adults. (
  • Effects of radiofrequency radiation exposure on blood-brain barrier permeability in male and female rats. (
  • Increased blood-brain barrier permeability in mammalian brain 7 days after exposure to the radiation from a GSM-900 mobile phone. (
  • Blood-brain barrier permeability and nerve cell damage in rat brain 14 and 28 days after exposure to microwaves from GSM mobile phones. (
  • Is the Subject Area "Blood-brain barrier permeability assay" applicable to this article? (
  • The porosity and permeability of the caved zone (gob) in a longwall operation impact many ventilation and methane control related issues, such as air leakage into the gob, the onset of spontaneous combustion, methane and air flow patterns in the gob, and the interaction of gob gas ventholes with the mining environment. (
  • Despite its importance, the gob is typically inaccessible for performing direct measurements of porosity and permeability. (
  • Thus, there has always been debate on the likely values of porosity and permeability of the caved zone and how these values can be predicted. (
  • The approach allows the calculation of porosity and permeability from the size distribution of broken rock material in the gob, which can be determined from image analyzes of gob material using the theories on a completely fragmented porous medium. (
  • The virtual fragmented fractal porous medium so generated is exposed to various uniaxial stresses to simulate gob compaction and porosity and permeability changes during this process. (
  • The results suggest that the gob porosity and permeability values can be predicted by this approach and the presented models are capable to produce values close to values documented by other researchers. (
  • The permeability of a medium is related to the porosity , but also to the shapes of the pores in the medium and their level of connectedness. (
  • A rock with 25% porosity and a permeability of 1 md will not yield a significant flow of water. (
  • The proposed method in this study combines core data (permeability) from 32 cored wells with identifiable reservoir rock types (RRTs) and log data (porosity and Swi) to develop drainage logderived capillary pressure (Pc) based on rock quality index (RQI) and then calculate J-function for each RRT which was used to calculate the initial water saturation in the reservoir. (
  • It was difficult to differentiate between the Mercury injection capillary curves (MIPCs) for a given RRT based of porosity and/or permeability ranges. (
  • Develop log-derived Pcs or J-functions using the available data (log-porosity, log-Swi, core permeability, and log-derived RRTs) to calculate the initial water saturation distribution in the entire reservoir. (
  • porosity and Check the quality of regression by plotting the right hand side (RHS) of equation 4 versus the LHS (see Figure 1). (
  • Permeability is influenced by the porosity of the substance (the fractional void volume), the degree of occlusion of the space through which the fluid flows, the diameter of the space through which the fluid flows, the viscosity of the fluid, and the surface interactions between the fluid and the walls of the vessel. (
  • In unconsolidated sands, better sorting systematically increases both permeability and porosity. (
  • Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (
  • Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. (
  • What determines glomerular capillary permeability? (
  • Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the capacity of a blood vessel wall to allow for the flow of small molecules (drugs, nutrients, water, ions) or even whole cells (lymphocytes on their way to the site of inflammation) in and out of the vessel. (
  • A substance released by stimulated or damaged lymphocytes that increases capillary permeability and the accumulation of mononuclear cells. (
  • citation needed] There are several techniques to measure vascular permeability to certain molecules. (
  • An example of increased vascular permeability is in the initial lesion of periodontal disease, in which the gingival plexus becomes engorged and dilated, allowing large numbers of neutrophils to extravasate and appear within the junctional epithelium and underlying connective tissue. (
  • Bates, D. O. & Harper, S. J. Regulation of vascular permeability by vascular endothelial growth factors. (
  • Estimation of apparent tumor vascular permeability from multiphoton fluorescence microscopic images of P22 rat sarcomas in vivo. (
  • In some patients with dengue hemorrhagic fever (DHF), vascular pathology can become severe, resulting in extensive microvascular permeability and plasma leakage into tissues and organs. (
  • Here, we showed that an MC-derived protease, tryptase, is consequential for promoting vascular permeability during DENV infection through inducing breakdown of endothelial cell tight junctions. (
  • Increased vascular permeability is considered a hallmark of ARDS. (
  • We believe that at present vascular permeability in the lungs cannot be studied in cell culture therefore, in our studies on the molecular mechanisms of pulmonary edema we use isolated perfused mouse and rat lungs to measure weight gain, the capillary filtration coefficient, vascular resistance and microvascular pressure and to isolate and characterize caveolae from pulmonary endothelial cells. (
  • Femtosecond Pulsed Laser Induces Local and Transient Vascular Permeability to Macromolecules with Minimal Invasiveness. (
  • In contrast to the protective effects of full-length netrin-1 on retinal microvasculature, the VI-V fragment promoted vascular permeability through the uncoordinated 5B (UNC5B) receptor. (
  • Nonspecific inhibition of collagenases or selective inhibition of MMP-9 decreased pathological vascular permeability in a murine model of diabetic retinal edema. (
  • This study reveals that netrin-1 degradation products are capable of modulating vascular permeability, suggesting that these fragments are of potential therapeutic interest for the treatment of DR. (
  • 1 They observed that vascular permeability is transient, restricted to the TMEM, and required for tumor cell dissemination. (
  • 2015). Real-Time Imaging Reveals Local, Transient Vascular Permeability, and Tumor Cell Intravasation Stimulated by TIE2hi Macrophage-Derived VEGFA . (
  • To overcome the permeability barrier different transport processes have been evolved for crossing the cell membrane. (
  • The importance of permeability is underlined by the integrity of cell membrane in maintaining the viability of cells. (
  • Different approaches have been applied to investigate membrane permeability as a measure of viability, by detecting permeability on account of hemolysis, turbidimetry and release of lactate dehydrogenase. (
  • Aeschbacher M, Reinhardt CA, Zbinden G (1986) A rapid cell membrane permeability test using fluorescent dyes and flow cytometry. (
  • High membrane permeability for melatonin. (
  • The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. (
  • Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). (
  • In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. (
  • A drastic rise in permeability of inner mitochondrial membrane (IMM), through consistent opening of a multi-protein channel referred to as the mitochondrial permeability transition pore (MPTP) results in mitochondrial dysfunction. (
  • These findings, combined with data on the permeability of the basement membrane and evidence that the endothelium may be a more important barrier than often supposed, are allowing a clearer understanding to emerge of how the 3 parts of the glomerular capillary wall jointly determine its functional properties. (
  • What is Membrane Permeability? (
  • Membrane permeability is essentially the ability of certain substances to pass in and out of an organic or semi-organic barrier. (
  • Permeability is largely dependent on the structure of the cell membrane , which is composed of two back-to-back layers of phospholipids . (
  • The plasma membrane features selective permeability, meaning that it allows some substances to enter but excludes others. (
  • Abnormalities of red cell membrane cation permeability are seen in several hereditary disorders. (
  • Any disturbances in membrane cation permeability alter cellular hydration and can cause numerous effects, including hemolysis. (
  • In contrast, the primary abnormality in DHSt is a change in the relative membrane permeability to K + . Efflux of K + is increased 2- to 4-fold and results in cation depletion, with decreased intracellular osmolality and water loss. (
  • We conclude that, compared to the basolateral membrane, the apical border of crypt colonocytes has a very low permeability-area product for NH3/NH4+. (
  • They will investigate properties of red cell membrane permeability. (
  • Polyamines decrease Escherichia coli outer membrane permeability. (
  • These results reveal the potential use of porins as targets for blocking agents and suggest that polyamines may act as endogenous modulators of outer membrane permeability. (
  • I get confused when we increase the permeability of the membrane to Na+. (
  • The Goldman equation, from my understanding, identifies the potential difference across the membrane for given ion concentrations and permeabilities at which the net flux of ions is zero: so there's no change in the system. (
  • Mitochondrial Permeability Transition Pore Assay Kit (ab239704) provides a fast, direct method of measuring cell death by measuring MPTP opening rather than relying on mitochondrial membrane potential alone. (
  • Induction of the permeability transition pore, mitochondrial membrane permeability transition (mPT or MPT), can lead to mitochondrial swelling and cell death through apoptosis or necrosis depending on the particular biological setting. (
  • Only treatment with the ionophore ETH129 (which allows electrophoretic Ca 2+ equilibration) caused Ca 2+ uptake followed by increased inner membrane permeability, membrane depolarization and Ca 2+ release. (
  • This ability is based on the highly selective and regulated permeability of the inner membrane. (
  • Before the emergence of chemiosmotic concepts, it had been reported that mitochondria could undergo a sudden permeability increase of the inner membrane, resulting in mitochondrial swelling ( Raaflaub, 1953a , b ). (
  • Since EDTA-treatment increases the permeability of the cell wall and cell membrane of the plant cell without denaturing proteins contained in the cells, we concluded that heating affected mainly the barrier formed by the cell wall, thus permitting a better passage of big molecules (enzymes). (
  • Glycerol release, TAGs content and whole membrane glycerol permeability were significantly increased in DCs as compared to UDCs. (
  • In addition, a significant reduction in whole membrane glycerol permeability was observed in LPS-DCs as compared to CTL-DCs. (
  • The relative contributions of AQP3, AQP7 and AQP9 (facilitated diffusion), as well as that of the phospholipid bilayer (simple diffusion), to the whole membrane glycerol permeability, were estimated biophysically in UDCs, CTL-DCs and LPS-DCs, using selective AQP inhibitors. (
  • New Salmonella typhimurium mutants with altered outer membrane permeability. (
  • Retrieved on August 09, 2020 from (
  • Functional analysis of cloned channels allowed to identify structural elements in the pore forming regions determining Ca2+ permeability for many types of ligand-gated channels. (
  • Their characterization is a challenging task since these unconventional reservoirs have tight pore throats (a few tens of nanometers) and low permeabilities (from microdarcies to nanodarcies). (
  • The mitochondrial permeability transition pore (MPT pore or MPTP) is a non-specific channel formed by components of the inner and outer mitochondrial membranes and appears to be involved in the release of mitochondrial components during cell death. (
  • Hunter and Haworth, 1979a , b ) named it Permeability Transition (PT) and proposed that it was mediated by a channel, the Permeability Transition Pore (PTP). (
  • alpha-Thrombin, bradykinin, and histamine are endogenous mediators that increase endothelial permeability. (
  • The concept of permeability is of importance in determining the flow characteristics of hydrocarbons in oil and gas reservoirs [1] , and of groundwater in aquifers [2] . (
  • For a rock to be considered as an exploitable hydrocarbon reservoir without stimulation, its permeability must be greater than approximately 100 md (depending on the nature of the hydrocarbon - gas reservoirs with lower permeabilities are still exploitable because of the lower viscosity of gas with respect to oil). (
  • A recent Applied Technology Workshop (ATW) held in San Antonio, Texas, "Refracturing in Low-Permeability Reservoirs," explored refracturing techniques and overall reservoir effects. (
  • Knowledge of the maximum- and minimum-permeability directions in anisotropic reservoirs helps to optimize injector and producer locations and is important for reservoir management, especially under secondary or enhanced recovery of hydrocarbons. (
  • For anisotropic reservoirs, such as naturally fractured fields or channel systems, knowing the permeability tensor directions and the ratios of the maximum to the minimum permeability in various locations in the field provides better opportunities to make optimal operational decisions. (
  • Concise and readable, Water Injection For Low Permeability Reservoirs provides operators with the proper workflow systems and engineering techniques for designing, planning and implementing water injection systems that will improve recovery factors. (
  • When used in low permeability or ultra-low permeability reservoirs, water injection is one of the most economical methods for ensuring maximum production rates. (
  • This book clearly explains the characteristics of ultra-low permeability reservoirs and linear flow theories. (
  • Cell membranes have selective permeability , meaning that they will allow certain substances to pass while forming a barrier against others. (
  • We found that, although the basolateral membranes have normal NH3/NH4+ permeability properties, there is no evidence for transport of either NH3 or NH4+ across the apical borders of these crypt cells. (
  • The permeability of the outer membranes of gram-negative bacteria to hydrophilic compounds is mostly due to the presence of porin channels. (
  • Opening allows increase in the permeability of the mitochondrial membranes to molecules of less than 1500 Daltons in molecular weight. (
  • The Caco-2 permeability assay provides a measure of the permeability of a test compound across the intestinal barrier and its potential for interactions with drug transporters. (
  • Published permeability coefficient ( K p ) data for the transport of a large group of compounds through mammalian epidermis were analyzed by a simple model based upon permeant size [molecular volume (MV) or molecular weight (MW)] and octanol/water partition coefficient ( K oct ). (
  • Addition of alpha-thrombin, bradykinin, or histamine increased the permeability coefficient of the HUVEC monolayer. (
  • At 30 min the permeability coefficient for alpha-thrombin was 4.92 x 10(-6) cm/sec while histamine was 4.47 x 10(-6) cm/sec. (
  • Maximum changes in the permeability coefficient were about three-fold control baseline values (1.59 x 10(-6) cm/sec). (
  • There was also a temporal difference in the magnitude of the permeability coefficient. (
  • Hello, I have porous zones in my model, and I need help determining the permeability alpha and inertial coefficient C2, mentioned in the Fluent help. (
  • The test data demonstrated that the least permeable coral concrete contained Eniwetok aggregate and after 3 months exposure had a coefficient of permeability approximating 0.000001 inches per hour for the liquid phase and approximating 0.000005 pounds per square inch per hour for the vapor phase. (
  • Q. What are the important factors affecting permeability? (
  • The major factors affecting permeability rate are texture and density. (
  • In these systems the permeability, B / H , is called the absolute permeability μ of the medium. (
  • Overall, then, we present a facile interpretation of a considerable body of skin permeability measurements that (a) very adequately describes the dependence of K p upon permeant size and lipophilicity, (b) generates parameters of considerable physicochemical and mechanistic relevance, and (c) implies that the SC lipids alone can fully characterize the barrier properties of mammalian skin. (
  • The significant biological subject, the permeability barrier, is incredibly diverse and vital for a vast assortment of crucial functions in the body. (
  • In Permeability Barrier: Methods and Protocols , a variety of experienced researchers contribute techniques to study this complex system in its many forms. (
  • Authoritative and practical, Permeability Barrier: Methods and Protocols serves as an ideal guide for all scientists seeking to further our understanding of this vital area of research. (
  • Epithelial barrier integrity is itself dynamic and matures over time starting soon after birth, though the mechanisms regulating dynamic permeability are poorly understood. (
  • Mutagenic analyses reveal that seipin plays a crucial role in permeability barrier synthesis during embryogenesis in Caenorhabditis elegans , and loss of seipin results in osmotically sensitive and dysfunctional embryos. (
  • Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz. (
  • Increased permeability of the blood-brain barrier induced by magnetic and electromagnetic fields. (
  • The increased BBB permeability was maintained in germ-free mice after birth and during adulthood and was associated with reduced expression of the tight junction proteins occludin and claudin-5, which are known to regulate barrier function in endothelial tissues. (
  • The 24-hour rhythm of permeability of a fly's blood (hemolymph) brain barrier. (
  • This week in Cell , a study led by Amita Sehgal, PhD, a professor of Neuroscience in the Perelman School of Medicine at the University of Pennsylvania and a Howard Hughes Medical Institute investigator, describes that the permeability of the fruit fly version of the barrier is higher at night versus during the day. (
  • Thus, although both microstructural rearrangements of the components of mucus as well as biochemical modifications to their adhesiveness may alter the overall permeability of the cervical mucus plug, our findings suggest that the latter mechanism plays a dominant role in the impairment of the function of this barrier during preterm birth. (
  • These events would affect the permeability of the alveolar epithelium and ultimately lead to epithelial barrier dysfunction and cell death. (
  • Researchers at MIT have made it possible to enhance skin permeability using ultrasound waves. (
  • The ultrasound treatment could improve skin permeability for up to 24 hours. (
  • The caved rock behind the advancing longwall face, known as the gob, can contain high void ratios, providing high permeability flow paths to the methane. (
  • 3M™ High Permeability Magnetic Shielding Sheet 1380 has a soft magnetic sheet sandwiched between layers of polyester film with a single-sided pressure-sensitive thermosetting rubber adhesive and liner. (
  • High permeability will allow fluids to move rapidly through rocks. (
  • For example, the youngest part of the tree, the sapwood, has relatively open vessels for water and mineral conduction and hence a high permeability. (
  • I can't find distinctive evidence between the difference in water permeability between PVC and TPU. (
  • If it's on the inside and both are filled with water then water permeability is not the issue. (
  • The water permeability of hardened coral concrete was investigated to learn the effects of mix design factors. (
  • Purified iron and many magnetic alloys have maximum relative permeabilities of 100,000 or more. (
  • A simple relationship between the conventional relative permeabilities and the generalized relative permeability coefficients is established based on several experimental sets. (
  • Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. (
  • Recent studies have reported unacceptable discrepancies (up to several decades) between intrinsic permeability ( k l ) measurements from different laboratories. (
  • Laboratory techniques are described for both steady-state and unsteady state measurements, and the calculation of relative permeability from field data is illustrated. (
  • The everted gut sac technique uses a more relevant sample size, and in vivo permeability measurements using Co-EDTA or lactulose are much more practical. (
  • Recent advances in laboratory and in situ testing techniques have permitted measurements of permeability and storage properties in progressively "tighter" media and investigation of transient flow under these conditions. (
  • where the permeability, μ , is a scalar if the medium is isotropic or a second rank tensor for an anisotropic medium. (
  • These studies predicted permeability to be isotropic in the undeformed configuration, and anisotropic under compression. (
  • Permeability is predicted to be anisotropic and inhomogeneous, independent of the state of strain, which is consistent with the morphology of the tissue. (
  • Our company is in search of some user experience tips/hints/help with purchasing, or even making, our own laboratory permeability testing equipment. (
  • These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. (
  • The complete paper describes a method using transient-test data rich with dynamic information aiming to provide fieldwide permeability distribution in well-spacing scale, which is relevant for estimating fluid movement and recovery. (
  • In large flow systems under steady state conditions the regional permeability can sometimes be determined, but systems with transient flow are more difficult to analyze. (
  • For the purpose of identifying subsurface permeability distribution, a geotomographic method named Hydropulse Tomography (HT) was developed. (
  • subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow sytems with many distinctive characteristics. (
  • In naturally occurring materials, the permeability values range over many orders of magnitude (see table below for an example of this range). (
  • Gob compaction by the overburden and associated permeability changes are determined from a three-dimensional geomechanical model which simulates the gob as a strain hardening granular material. (
  • So, Mitchell, Hooper and Campenella did research on compaction moisture content and remolded permeability. (
  • We provide permeability assays for small molecule formulations such as pharmaceuticals, industrial chemicals and consumer products. (
  • Our permeability assays utilize the C2BBe1 cell line, a subclone of the original Caco-2 cell line. (
  • Soils usually accept water rapidly at first and then at a reduced rate until the permeability steady state rate is reached. (
  • Does any one have any idea about improving the permeability of lipid layer ( espeacially ascaroside layer)? (
  • Studying the permeability characterization of the different polymer material (homogeneous and heterogeneous polymer system) to the different packaging gases, in different environmental condition, is crucial to understand if the selected material is adapted to the chosen food contact field. (
  • The aim of this report was to collect information about the state of the art on the permeability characteristics of the polymer packages used on food field. (
  • and an inert porous filler optionally having a surface modifying agent coated thereon, the inert porous filler being present in an amount effective to reduce the ratio of the carbon dioxide permeability to the oxygen permeability of the film, and wherein the filler has a particle size greater than the intrinsic film thickness of the film forming polymer. (
  • 3. A controlled permeability film according to claim 2, wherein the polyolefin polymer is a low density polyethylene. (
  • Conventional relative permeability, as well as generalized relative permeability coefficients (with the viscous coupling terms taken explicitly into account) were determined with a new method that is based on a B-spline functional representation combined with standard constrained optimization techniques. (
  • To determine a possible intracellular mechanism of the altered permeability coefficients, HUVEC were labeled with FURA-2 and intracellular calcium was monitored by digital fluorescence ratio imaging. (
  • Calcium permeability of ligand-gated channels. (
  • These data also show, for the first time, that histamine and alpha-thrombin increased permeability by calcium-dependent intracellular pathways, but bradykinin operates through a calcium-independent mechanism. (
  • 6] C. Baiocchi and A. Friedman , A filtration problem in a porous medium with variable permeability , Ann. (
  • The present invention relates to controlled permeability film compositions for use in controlled atmosphere packaging and to the protective packaging of sensitive produce therewith. (
  • The present invention relates generally to the composition and method for reducing the permeability of subterranean formations penetrated by a wellbore. (
  • Permeability is the property of rocks that is an indication of the ability for fluids (gas or liquid) to flow through rocks. (
  • Such "tight" rocks are usually artificially stimulated (fractured or acidized) to create permeability and yield a flow. (
  • 8. A method as claimed in claim 7 wherein the method further includes producing or injecting through the one or more permeability control devices and producing a flow profile that is generally uniform along the borehole. (
  • A. Permeability indicates the ability of liquids or gases to flow under pressure through concrete. (
  • This review attempts to synthesize the diverse contributions of various disciplines to the problem of flow in low-permeability environments. (
  • Small-scale experimental results form much of the basis for analyses of flow in low-permeability environments which occurs on scales of time and size too large to permit direct observation. (
  • Looking at the local anisotropy of permeability, we may infer that the arrangement of the collagen fibre network plays an important role in directing fluid flow to optimise tissue functioning. (
  • A detailed description is given of an experimental method for determiningrelative permeability of porous media to gas. (
  • The permeability of the swimbladder to gas was measured as the conductance to oxygen in seven species of fish. (
  • Bestech Australia introduces a new high performance oxygen permeability tester designed to measure the oxygen transmission rate of film and package products. (
  • The new OX2/231 oxygen permeability tester helps determine the oxygen transmission rate of plastic films, composite films, sheeting, plastic bottles, plastic bags and other packages. (
  • Featuring two test modes for films and packages for accurate testing, the OX2/231 oxygen permeability testers can test three specimens simultaneously, and then export the test results for analysis. (
  • The advances in petroleum reservoir technology during the past decade havemade increasingly apparent the desirability of a simple, rapid, reliable methodfor obtaining relative permeability data on small cores. (
  • The over-all apparent single-phase permeability of fracture-rock systems was studied using two different two-dimensional models. (
  • A discussion of techniques for determing wettability is included, along with theoretical and empirical methods for the calculation of relative permeability, and prediction techniques. (
  • The aim of this study was to assess both glycerol permeability and metabolism in undifferentiated 3T3-L1 cells (UDCs) as well as in untreated (CTL-DCs) versus lipopolysaccharide (LPS-DCs)-treated differentiated 3T3-L1 adipocytes. (
  • On the anisotropy and inhomogeneity of permeability in articular cartilage. (
  • Therefore, the aim of this study was to express the permeability of cartilage accounting for the microstructural anisotropy and inhomogeneity caused by the collagen fibres. (
  • In electromagnetism , permeability is the measure of the resistance of a material against the formation of a magnetic field , otherwise known as distributed inductance in transmission line theory . (
  • The permeability constant μ 0 , also known as the magnetic constant or the permeability of free space, is a measure of the amount of resistance encountered when forming a magnetic field in a classical vacuum . (
  • In general, permeability is not a constant, as it can vary with the position in the medium, the frequency of the applied magnetic field, humidity , temperature, and other parameters. (
  • In a nonlinear medium , the permeability can depend on the strength of the magnetic field. (
  • Magnetic permeability μ (Greek mu) is thus defined as μ = B / H. Magnetic flux density B is a measure of the actual magnetic field within a material considered as a concentration of magnetic field lines, or flux, per unit cross-sectional area. (
  • Permeability, also called magnetic permeability, is a constant of proportionality that exists between magnetic induction and magnetic field intensity. (
  • The permeability factors of some substances change with rising or falling temperature, or with the intensity of the applied magnetic field. (
  • In overhydrated hereditary stomatocytosis, the major defect is a marked asymmetrical increase in passive Na + and K + permeability. (
  • Permeability has long been discussed as a potential biological marker of risk of developing inflammatory bowel disease. (
  • The authors have developed a new methodology to determine both horizontal and vertical variations in the permeability of the gob. (
  • In these instances various sublayers create a difference between horizontal and vertical permeability. (
  • Sandstones may vary in permeability from less than one to over 50,000 millidarcys (md). (
  • Permeability values for sandstones range typically from a fraction of a darcy to several darcys . (
  • As the magnetizing field increases, the relative permeability increases, reaches a maximum, and then decreases. (
  • Anattempt is made to correlate total permeability and rock textural factors withrelative permeability to gas. (
  • Actually the optimization behaviour of packaging permeability is of crucial importance, in order to extend the food shelf-life and to reach the best engineering solution. (
September 26, 1885 - Scientific American