Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.
The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.
The number of PLATELETS per unit volume in a sample of venous BLOOD.
The process whereby PLATELETS adhere to something other than platelets, e.g., COLLAGEN; BASEMENT MEMBRANE; MICROFIBRILS; or other "foreign" surfaces.
Surface glycoproteins on platelets which have a key role in hemostasis and thrombosis such as platelet adhesion and aggregation. Many of these are receptors.
A CXC chemokine that is found in the alpha granules of PLATELETS. The protein has a molecular size of 7800 kDa and can occur as a monomer, a dimer or a tetramer depending upon its concentration in solution. Platelet factor 4 has a high affinity for HEPARIN and is often found complexed with GLYCOPROTEINS such as PROTEIN C.
An enzyme formed from PROTHROMBIN that converts FIBRINOGEN to FIBRIN.
Adenosine 5'-(trihydrogen diphosphate). An adenine nucleotide containing two phosphate groups esterified to the sugar moiety at the 5'-position.
The transfer of blood platelets from a donor to a recipient or reinfusion to the donor.
A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.
Platelet membrane glycoprotein complex important for platelet adhesion and aggregation. It is an integrin complex containing INTEGRIN ALPHAIIB and INTEGRIN BETA3 which recognizes the arginine-glycine-aspartic acid (RGD) sequence present on several adhesive proteins. As such, it is a receptor for FIBRINOGEN; VON WILLEBRAND FACTOR; FIBRONECTIN; VITRONECTIN; and THROMBOSPONDINS. A deficiency of GPIIb-IIIa results in GLANZMANN THROMBASTHENIA.
Platelet membrane glycoprotein complex essential for normal platelet adhesion and clot formation at sites of vascular injury. It is composed of three polypeptides, GPIb alpha, GPIb beta, and GPIX. Glycoprotein Ib functions as a receptor for von Willebrand factor and for thrombin. Congenital deficiency of the GPIb-IX complex results in Bernard-Soulier syndrome. The platelet glycoprotein GPV associates with GPIb-IX and is also absent in Bernard-Soulier syndrome.
Very large BONE MARROW CELLS which release mature BLOOD PLATELETS.
A platelet-specific protein which is released when platelets aggregate. Elevated plasma levels have been reported after deep venous thrombosis, pre-eclampsia, myocardial infarction with mural thrombosis, and myeloproliferative disorders. Measurement of beta-thromboglobulin in biological fluids by radioimmunoassay is used for the diagnosis and assessment of progress of thromboembolic disorders.
A series of progressive, overlapping events, triggered by exposure of the PLATELETS to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable hemostatic plug.
Disorders caused by abnormalities in platelet count or function.
A subnormal level of BLOOD PLATELETS.
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.
Laboratory examination used to monitor and evaluate platelet function in a patient's blood.
Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.
2-Octylcyclopentaneheptanoic acids. The family of saturated carbon-20 cyclic fatty acids that represent the parent compounds of the prostaglandins.
Cell adhesion molecule and CD antigen that mediates the adhesion of neutrophils and monocytes to activated platelets and endothelial cells.
A high-molecular-weight plasma protein, produced by endothelial cells and megakaryocytes, that is part of the factor VIII/von Willebrand factor complex. The von Willebrand factor has receptors for collagen, platelets, and ristocetin activity as well as the immunologically distinct antigenic determinants. It functions in adhesion of platelets to collagen and hemostatic plug formation. The prolonged bleeding time in VON WILLEBRAND DISEASES is due to the deficiency of this factor.
The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. (From Martindale, The Extra Pharmacopoeia, 30th ed, p5)
The process of generating thrombocytes (BLOOD PLATELETS) from the pluripotent HEMATOPOIETIC STEM CELLS in the BONE MARROW via the MEGAKARYOCYTES. The humoral factor with thrombopoiesis-stimulating activity is designated THROMBOPOIETIN.
A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).
The number of LEUKOCYTES and ERYTHROCYTES per unit volume in a sample of venous BLOOD. A complete blood count (CBC) also includes measurement of the HEMOGLOBIN; HEMATOCRIT; and ERYTHROCYTE INDICES.
An unstable intermediate between the prostaglandin endoperoxides and thromboxane B2. The compound has a bicyclic oxaneoxetane structure. It is a potent inducer of platelet aggregation and causes vasoconstriction. It is the principal component of rabbit aorta contracting substance (RCS).
The process of the interaction of BLOOD COAGULATION FACTORS that results in an insoluble FIBRIN clot.
The process which spontaneously arrests the flow of BLOOD from vessels carrying blood under pressure. It is accomplished by contraction of the vessels, adhesion and aggregation of formed blood elements (eg. ERYTHROCYTE AGGREGATION), and the process of BLOOD COAGULATION.
Human alloantigens expressed only on platelets, specifically on platelet membrane glycoproteins. These platelet-specific antigens are immunogenic and can result in pathological reactions to transfusion therapy.
Formation and development of a thrombus or blood clot in the blood vessel.
A humoral factor that stimulates the production of thrombocytes (BLOOD PLATELETS). Thrombopoietin stimulates the proliferation of bone marrow MEGAKARYOCYTES and their release of blood platelets. The process is called THROMBOPOIESIS.
Condensed areas of cellular material that may be bounded by a membrane.
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.
An opioid analgesic chemically related to and with an action resembling that of MEPERIDINE, but more rapid in onset and of shorter duration. It has been used in obstetrics, as pre-operative medication, for minor surgical procedures, and for dental procedures. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1067)
Physiologically active compounds found in many organs of the body. They are formed in vivo from the prostaglandin endoperoxides and cause platelet aggregation, contraction of arteries, and other biological effects. Thromboxanes are important mediators of the actions of polyunsaturated fatty acids transformed by cyclooxygenase.
A mixture of the mesylates (methane sulfonates) of DIHYDROERGOCORNINE; DIHYDROERGOCRISTINE; and the alpha- and beta-isomers of DIHYDROERGOCRYPTINE. The substance produces a generalized peripheral vasodilation and a fall in arterial pressure and has been used to treat symptoms of mild to moderate impairment of mental function in the elderly.
A phosphodiesterase inhibitor which inhibits platelet aggregation. Formerly used as an antineoplastic.
The process by which blood or its components are kept viable outside of the organism from which they are derived (i.e., kept from decay by means of a chemical agent, cooling, or a fluid substitute that mimics the natural state within the organism).
A plant genus of the family ROSACEAE. The common names of chokeberry or chokecherry are also used for some species of PRUNUS.
A deficiency or absence of FIBRINOGEN in the blood.
Duration of blood flow after skin puncture. This test is used as a measure of capillary and platelet function.
A vasoconstrictor found in ergot of Central Europe. It is a serotonin agonist that has been used as an oxytocic agent and in the treatment of MIGRAINE DISORDERS.
A tricyclic antidepressant that has actions and uses similar to those of AMITRIPTYLINE, but has only weak antimuscarinic and sedative effects. (From Martindale, The Extra Pharmacopoeia, 30th ed, p257)
Cell surface proteins that bind THROMBOXANES with high affinity and trigger intracellular changes influencing the behavior of cells. Some thromboxane receptors act via the inositol phosphate and diacylglycerol second messenger systems.
The rate dynamics in chemical or physical systems.
Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.
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 active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.
Platelet membrane glycoprotein IIb is an integrin alpha subunit that heterodimerizes with INTEGRIN BETA3 to form PLATELET GLYCOPROTEIN GPIIB-IIIA COMPLEX. It is synthesized as a single polypeptide chain which is then postranslationally cleaved and processed into two disulfide-linked subunits of approximately 18 and 110 kDa in size.
A prostaglandin that is a powerful vasodilator and inhibits platelet aggregation. It is biosynthesized enzymatically from PROSTAGLANDIN ENDOPEROXIDES in human vascular tissue. The sodium salt has been also used to treat primary pulmonary hypertension (HYPERTENSION, PULMONARY).
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
A phospholipid from the platelet membrane that contributes to the blood clotting cascade by forming a phospholipid-protein complex (THROMBOPLASTIN) which serves as a cofactor with FACTOR VIIA to activate FACTOR X in the extrinsic pathway of BLOOD COAGULATION.
The prototypical tricyclic antidepressant. It has been used in major depression, dysthymia, bipolar depression, attention-deficit disorders, agoraphobia, and panic disorders. It has less sedative effect than some other members of this therapeutic group.
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.
An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.
Hemorrhagic and thrombotic disorders that occur as a consequence of abnormalities in blood coagulation due to a variety of factors such as COAGULATION PROTEIN DISORDERS; BLOOD PLATELET DISORDERS; BLOOD PROTEIN DISORDERS or nutritional conditions.
The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.
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.
Drugs or agents which antagonize or impair any mechanism leading to blood platelet aggregation, whether during the phases of activation and shape change or following the dense-granule release reaction and stimulation of the prostaglandin-thromboxane system.
Elements of limited time intervals, contributing to particular results or situations.
A group of compounds derived from unsaturated 20-carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway. They are extremely potent mediators of a diverse group of physiological processes.
An ionophorous, polyether antibiotic from Streptomyces chartreusensis. It binds and transports CALCIUM and other divalent cations across membranes and uncouples oxidative phosphorylation while inhibiting ATPase of rat liver mitochondria. The substance is used mostly as a biochemical tool to study the role of divalent cations in various biological systems.
An unsaturated, essential fatty acid. It is found in animal and human fat as well as in the liver, brain, and glandular organs, and is a constituent of animal phosphatides. It is formed by the synthesis from dietary linoleic acid and is a precursor in the biosynthesis of prostaglandins, thromboxanes, and leukotrienes.
Cell surface receptors that are specific for THROMBOPOIETIN. They signal through interaction with JANUS KINASES such as JANUS KINASE 2.
A chelating agent that sequesters a variety of polyvalent cations such as CALCIUM. It is used in pharmaceutical manufacturing and as a food additive.
An ergot derivative that is a congener of LYSERGIC ACID DIETHYLAMIDE. It antagonizes the effects of serotonin in blood vessels and gastrointestinal smooth muscle, but has few of the properties of other ergot alkaloids. Methysergide is used prophylactically in migraine and other vascular headaches and to antagonize serotonin in the carcinoid syndrome.
Field of chemistry that pertains to immunological phenomena and the study of chemical reactions related to antigen stimulation of tissues. It includes physicochemical interactions between antigens and antibodies.
The sum of the weight of all the atoms in a molecule.
A subclass of purinergic P2Y receptors that have a preference for ADP binding and are coupled to GTP-BINDING PROTEIN ALPHA SUBUNIT, GI. The P2Y12 purinergic receptors are found in PLATELETS where they play an important role regulating PLATELET ACTIVATION.
Cell surface receptors that bind prostaglandins with high affinity and trigger intracellular changes which influence the behavior of cells. Prostaglandin receptor subtypes have been tentatively named according to their relative affinities for the endogenous prostaglandins. They include those which prefer prostaglandin D2 (DP receptors), prostaglandin E2 (EP1, EP2, and EP3 receptors), prostaglandin F2-alpha (FP receptors), and prostacyclin (IP receptors).
Organic compounds that contain 1,2-diphenylethylene as a functional group.
Antibodies produced by a single clone of cells.
Disorder characterized by a decrease or lack of platelet dense bodies in which the releasable pool of adenine nucleotides and 5HT are normally stored.
A highly acidic mucopolysaccharide formed of equal parts of sulfated D-glucosamine and D-glucuronic acid with sulfaminic bridges. The molecular weight ranges from six to twenty thousand. Heparin occurs in and is obtained from liver, lung, mast cells, etc., of vertebrates. Its function is unknown, but it is used to prevent blood clotting in vivo and vitro, in the form of many different salts.
An antibiotic mixture of two components, A and B, obtained from Nocardia lurida (or the same substance produced by any other means). It is no longer used clinically because of its toxicity. It causes platelet agglutination and blood coagulation and is used to assay those functions in vitro.
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
A congenital bleeding disorder with prolonged bleeding time, absence of aggregation of platelets in response to most agents, especially ADP, and impaired or absent clot retraction. Platelet membranes are deficient in or have a defect in the glycoprotein IIb-IIIa complex (PLATELET GLYCOPROTEIN GPIIB-IIIA COMPLEX).
The relationship between the dose of an administered drug and the response of the organism to the drug.
A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin.
Peptides composed of between two and twelve amino acids.
Any form of purpura in which the PLATELET COUNT is decreased. Many forms are thought to be caused by immunological mechanisms.
Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.
The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.
Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.
A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food.
Technique using an instrument system for making, processing, and displaying one or more measurements on individual cells obtained from a cell suspension. Cells are usually stained with one or more fluorescent dyes specific to cell components of interest, e.g., DNA, and fluorescence of each cell is measured as it rapidly transverses the excitation beam (laser or mercury arc lamp). Fluorescence provides a quantitative measure of various biochemical and biophysical properties of the cell, as well as a basis for cell sorting. Other measurable optical parameters include light absorption and light scattering, the latter being applicable to the measurement of cell size, shape, density, granularity, and stain uptake.
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
Venoms from snakes of the subfamily Crotalinae or pit vipers, found mostly in the Americas. They include the rattlesnake, cottonmouth, fer-de-lance, bushmaster, and American copperhead. Their venoms contain nontoxic proteins, cardio-, hemo-, cyto-, and neurotoxins, and many enzymes, especially phospholipases A. Many of the toxins have been characterized.
An alkaloid found in the roots of Rauwolfia serpentina and R. vomitoria. Reserpine inhibits the uptake of norepinephrine into storage vesicles resulting in depletion of catecholamines and serotonin from central and peripheral axon terminals. It has been used as an antihypertensive and an antipsychotic as well as a research tool, but its adverse effects limit its clinical use.
A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.
The quantity of volume or surface area of CELLS.
A layer of epithelium that lines the heart, blood vessels (ENDOTHELIUM, VASCULAR), lymph vessels (ENDOTHELIUM, LYMPHATIC), and the serous cavities of the body.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
Increased numbers of platelets in the peripheral blood. (Dorland, 27th ed)
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
Endogenous substances, usually proteins, that are involved in the blood coagulation process.
A preparation consisting of PLATELETS concentrated in a limited volume of PLASMA. This is used in various surgical tissue regeneration procedures where the GROWTH FACTORS in the platelets enhance wound healing and regeneration.
A stable, physiologically active compound formed in vivo from the prostaglandin endoperoxides. It is important in the platelet-release reaction (release of ADP and serotonin).
Adherence of cells to surfaces or to other cells.
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.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Synthetic compounds that are analogs of the naturally occurring prostaglandin endoperoxides and that mimic their pharmacologic and physiologic activities. They are usually more stable than the naturally occurring compounds.
Organic nitrogenous bases. Many alkaloids of medical importance occur in the animal and vegetable kingdoms, and some have been synthesized. (Grant & Hackh's Chemical Dictionary, 5th ed)
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).
The number of WHITE BLOOD CELLS per unit volume in venous BLOOD. A differential leukocyte count measures the relative numbers of the different types of white cells.
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.
Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
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.
Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.
The development and formation of various types of BLOOD CELLS. Hematopoiesis can take place in the BONE MARROW (medullary) or outside the bone marrow (HEMATOPOIESIS, EXTRAMEDULLARY).
A familial coagulation disorder characterized by a prolonged bleeding time, unusually large platelets, and impaired prothrombin consumption.
Proteins prepared by recombinant DNA technology.
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
A highly polar organic liquid, that is used widely as a chemical solvent. Because of its ability to penetrate biological membranes, it is used as a vehicle for topical application of pharmaceuticals. It is also used to protect tissue during CRYOPRESERVATION. Dimethyl sulfoxide shows a range of pharmacological activity including analgesia and anti-inflammation.
A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
A family of proteinase-activated receptors that are specific for THROMBIN. They are found primarily on PLATELETS and on ENDOTHELIAL CELLS. Activation of thrombin receptors occurs through the proteolytic action of THROMBIN, which cleaves the N-terminal peptide from the receptor to reveal a new N-terminal peptide that is a cryptic ligand for the receptor. The receptors signal through HETEROTRIMERIC GTP-BINDING PROTEINS. Small synthetic peptides that contain the unmasked N-terminal peptide sequence can also activate the receptor in the absence of proteolytic activity.
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)
A chromatographic technique that utilizes the ability of biological molecules to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Drugs that bind to but do not activate serotonin receptors, thereby blocking the actions of serotonin or SEROTONIN RECEPTOR AGONISTS.
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.
The preparation of platelet concentrates with the return of red cells and platelet-poor plasma to the donor.
A calcium-activated enzyme that catalyzes the hydrolysis of ATP to yield AMP and orthophosphate. It can also act on ADP and other nucleoside triphosphates and diphosphates. EC 3.6.1.5.
Univalent antigen-binding fragments composed of one entire IMMUNOGLOBULIN LIGHT CHAIN and the amino terminal end of one of the IMMUNOGLOBULIN HEAVY CHAINS from the hinge region, linked to each other by disulfide bonds. Fab contains the IMMUNOGLOBULIN VARIABLE REGIONS, which are part of the antigen-binding site, and the first IMMUNOGLOBULIN CONSTANT REGIONS. This fragment can be obtained by digestion of immunoglobulins with the proteolytic enzyme PAPAIN.
A stable prostaglandin endoperoxide analog which serves as a thromboxane mimetic. Its actions include mimicking the hydro-osmotic effect of VASOPRESSIN and activation of TYPE C PHOSPHOLIPASES. (From J Pharmacol Exp Ther 1983;224(1): 108-117; Biochem J 1984;222(1):103-110)
A metallic element, atomic number 49, atomic weight 114.82, symbol In. It is named from its blue line in the spectrum. (From Dorland, 28th ed)
Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.
Collagen receptors are cell surface receptors that modulate signal transduction between cells and the EXTRACELLULAR MATRIX. They are found in many cell types and are involved in the maintenance and regulation of cell shape and behavior, including PLATELET ACTIVATION and aggregation, through many different signaling pathways and differences in their affinities for collagen isoforms. Collagen receptors include discoidin domain receptors, INTEGRINS, and glycoprotein VI.
Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behavior of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.
An absence of warmth or heat or a temperature notably below an accustomed norm.
The deformation and flow behavior of BLOOD and its elements i.e., PLASMA; ERYTHROCYTES; WHITE BLOOD CELLS; and BLOOD PLATELETS.
The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.
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.
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)
Thrombocytopenia occurring in the absence of toxic exposure or a disease associated with decreased platelets. It is mediated by immune mechanisms, in most cases IMMUNOGLOBULIN G autoantibodies which attach to platelets and subsequently undergo destruction by macrophages. The disease is seen in acute (affecting children) and chronic (adult) forms.
A family of related, adhesive glycoproteins which are synthesized, secreted, and incorporated into the extracellular matrix of a variety of cells, including alpha granules of platelets following thrombin activation and endothelial cells. They interact with a number of BLOOD COAGULATION FACTORS and anticoagulant factors. Five distinct forms have been identified, thrombospondin 1, -2, -3, -4, and cartilage oligomeric matrix protein (COMP). They are involved in cell adhesion, platelet aggregation, cell proliferation, angiogenesis, tumor metastasis, VASCULAR SMOOTH MUSCLE growth, and tissue repair.
A rare, inherited platelet disorder characterized by a selective deficiency in the number and contents of platelet alpha-granules. It is associated with THROMBOCYTOPENIA, enlarged platelets, and prolonged bleeding time.
Bleeding or escape of blood from a vessel.

Values of three coagulation screening tests of precolostral calves. (1/11030)

Prothrombin times, partial thromboplastin times and platelet counts were performed to determine normal values and to screen for coagulation defects of precolostral calves. The precolostral calves were in two groups: one group of a few calves was tested two years before the second larger group. The results for both groups were similar. The tests were performed on postcolostral calves and on mature cows to compare their values with those of precolostral calves. The mean values of prothrombin times and partial thromboplastin times of precolostral calves in the first group were 18.8 seconds and 54.8 seconds respectively. The mean values of prothrombin times and partial thromboplastin times of precolostral calves in the second group were 18.8 seconds and 50.8 seconds respectively. The mean platelet count was 422,400/cmm for the first group and 482,800/cmm for the second group.  (+info)

Enhanced myocardial glucose use in patients with a deficiency in long-chain fatty acid transport (CD36 deficiency). (2/11030)

CD36 is a multifunctional, 88 kDa glycoprotein that is expressed on platelets and monocytes/macrophages. CD36 also has high homology with the long-chain fatty acid (LFA) transporter in the myocardium. Although platelet and monocyte CD36 levels can indicate a CD36 deficiency, they cannot predict specific clinical manifestations in the myocardium of a given person. We examined the hypothesis that a deficiency in LFA transport augments myocardial glucose uptake in patients with a type I CD36 deficiency. METHODS: Seven fasting patients with a type I CD36 deficiency and 9 controls were assessed by cardiac radionuclide imaging using beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) as a LFA tracer and by PET with 18F-fluorodeoxyglucose (FDG). RESULTS: None of the patients with a CD36 deficiency showed myocardial uptake of BMIPP. The percentage dose uptake of BMIPP in these subjects was significantly lower than that in normal controls (1.31+/-0.24 versus 2.90+/-0.2; P < 0.005). PET studies revealed that myocardial FDG accumulation was substantially increased in patients with a CD36 deficiency. Quantitative analysis showed that the percentage dose uptake of FDG in patients with a CD36 deficiency was significantly higher than that in normal controls (1.28+/-0.35 versus 0.43+/-0.22; P< 0.01). CONCLUSION: CD36 functions as a major myocardial LFA transporter and its absence may cause a compensatory upregulation of myocardial glucose uptake.  (+info)

Tyrosine phosphorylation of SLP-76 is downstream of Syk following stimulation of the collagen receptor in platelets. (3/11030)

Collagen-related peptide (CRP), a collagen homologue, induces platelet activation through a tyrosine kinase-dependent pathway, leading to sequential tyrosine phosphorylation of Fc receptor (FcR) gamma-chain, Syk, and phospholipase C-gamma2. Here we report that CRP and the platelet low affinity immune receptor FcgammaRIIA stimulate tyrosine phosphorylation of the T cell adapter SLP-76, whereas the G protein-coupled receptor agonist thrombin induces only minor tyrosine phosphorylation. This suggests that SLP-76 has a specific role downstream of receptors that signal via an immunoreceptor tyrosine-based activation motif. Immunoprecipitation studies demonstrate association of SLP-76 with SLAP-130, Vav, Fyn, Lyn, and the FcR gamma-chain in CRP-stimulated platelets. Several of these proteins, including SLP-76, undergo tyrosine phosphorylation in in vitro kinase assays performed on SLP-76 immunoprecipitates. Tyrosine phosphorylation of all of these proteins in the in vitro kinase assay was abrogated by the Src family kinase inhibitor PP1, suggesting that it is mediated by either Fyn or Lyn. The physiological significance of this is uncertain, however, since tyrosine phosphorylation of SLP-76 in vivo is not altered in either Fyn- or Lyn-deficient platelets. CRP stimulation of Syk-deficient platelets demonstrated that in vivo tyrosine phosphorylation of SLP-76 is downstream of Syk. The absence of Syk in the SLP-76 immunoprecipitates raises the possibility that another protein is responsible for bringing SLP-76 to Syk. Candidates for this include those proteins that co-immunoprecipitate with SLP-76, including the FcR gamma-chain. Tyrosine phosphorylation of PLC-gamma2 and Ca2+ mobilization is markedly attenuated in SLP-76-deficient platelets following CRP stimulation, suggesting that the adapter plays a critical role in the regulation of the phospholipase. The increase in tyrosine phosphorylation of SLAP-130 in response to CRP is also inhibited in SLP-76-deficient platelets, placing it downstream of SLP-76. This work identifies SLP-76 as an important adapter molecule that is regulated by Syk and lies upstream of SLAP-130 and PLC-gamma2 in CRP-stimulated platelets.  (+info)

Changes in haematological parameters and iron metabolism associated with a 1600 kilometre ultramarathon. (4/11030)

OBJECTIVE: To investigate haematological variations and iron related changes in the serum of participants in a 1600 kilometre ultramarathon run. PARTICIPANTS: Seven male and two female participants in a 1600 km foot race. METHODS: Blood samples were obtained from the participants before, after four and 11 days of running, and at the end of the event. Samples were analysed by standard methods for haemoglobin, packed cell volume, total red cell count, mean red cell volume, mean red cell haemoglobin, total white cell count and differential, platelets, reticulocytes, iron, ferritin, total iron binding capacity, percentage transferrin saturation, haptoglobin, and bilirubin and corrected for changes in plasma volume. RESULTS: The following variables decreased during the event (p < 0.05): haemoglobin, packed cell volume, mean red cell volume, percentage lymphocytes, percentage monocytes, serum iron, total iron binding capacity, and percentage transferrin saturation. Increases (p < 0.05) were found in plasma volume, total red cell count (day 4 only), total white cell count, percentage and absolute numbers of neutrophils and reticulocytes, absolute numbers of lymphocytes and monocytes (day 4 only), absolute numbers of eosinophils (day 11 and race end), absolute numbers of basophils (race end only), platelets, ferritin, haptoglobin, and bilirubin (day 4 only). CONCLUSION: Ultramarathon running is associated with a wide range of changes in haematological parameters, many of which are related to the normal acute phase response to injury. These should not be confused with indicators of disease.  (+info)

The Megakaryocyte/Platelet-specific enhancer of the alpha2beta1 integrin gene: two tandem AP1 sites and the mitogen-activated protein kinase signaling cascade. (5/11030)

The alpha2beta1 integrin, a collagen receptor on platelets and megakaryocytes, is required for normal platelet function. Transcriptional regulation of the alpha2 integrin gene in cells undergoing megakaryocytic differentiation requires a core promoter between bp -30 and -92, a silencer between bp -92 and -351, and megakaryocytic enhancers in the distal 5' flank. We have now identified a 229-bp region of the distal 5' flank of the alpha2 integrin gene required for high-level enhancer activity in cells with megakaryocytic features. Two tandem AP1 binding sites with dyad symmetry are required for enhancer activity and for DNA-protein complex formation with members of the c-fos/c-jun family. The requirement for AP1 activation suggested a role for the mitogen-activated protein kinase (MAPK) signaling pathway in regulating alpha2 integrin gene expression. Inhibition of the MAP kinase cascade with PD98059, a specific inhibitor of MAPK kinase 1, prevented the expression of the alpha2 integrin subunit in cells induced to become megakaryocytic. We provide a model of megakaryocytic differentiation in which expression of the alpha2 integrin gene requires signaling via the MAP kinase pathway to activate two tandem AP1 binding sites in the alpha2 integrin enhancer.  (+info)

Activation of stimulus-specific serine esterases (proteases) in the initiation of platelet secretion. I. Demonstration with organophosphorus inhibitors. (6/11030)

The effect of organophosphorus inhibitors of serine esterases (proteases) on secretion from washed rabbit platelets was examined. Five noncytotoxic stimuli were employed: collagen, thrombin, heterologous anti-platelet antibody (in the absence of complement), rabbit C3 bound to zymosan, and platelet activating factor derived from antigen-stimulated, IgE-sensitized rabbit basophils. Diisoprophyl phosphofluoridate, three series of p-nitrophenyl ethyl phosphonates, and a series of cyclohexyl phenylalkylphosphonofluridates were all found to be inhibitory to the platelet secretion. These are irreversible inhibitors of serine proteases but in this system were only inhibitory if added to the platelets concurrently with the stimuli. Pretreatment of either the platelets or the stimuli with the inhibitors followed by washing, was without effect on the subsequent reaction. This suggested the involvement of stimulus-activatable serine proteases in the secretory process. The concept was supported by finding that nonphosphorylating phosphonates or hydrolyzed phosphonates or phosphonofluoridates were without inhibitory action. The effect of a series of phosphonates or phosphonoflouridates in inhibiting each stimulus exhibited a unique activity-structure profile. The demonstration of such unique profiles with four series of inhibitors for each of the five stimuli was interpreted as demonstrating that a specific activatable serine protease was involved in the platelet secretory response to each stimulus.  (+info)

Glycoprotein (GP) Ib-IX-transfected cells roll on a von Willebrand factor matrix under flow. Importance of the GPib/actin-binding protein (ABP-280) interaction in maintaining adhesion under high shear. (7/11030)

Adhesion of platelets to sites of vascular injury is critical for hemostasis and thrombosis and is dependent on the binding of the vascular adhesive protein von Willebrand factor (vWf) to the glycoprotein (GP) Ib-V-IX complex on the platelet surface. A unique but poorly defined characteristic of this receptor/ligand interaction is its ability to support platelet adhesion under conditions of high shear stress. To examine the structural domains of the GPIb-V-IX complex involved in mediating cell adhesion under flow, we have expressed partial (GPIb-IX), complete (GPIb-V-IX), and mutant (GPIbalpha cytoplasmic tail mutants) receptor complexes on the surface of Chinese hamster ovary (CHO) cells and examined their ability to adhere to a vWf matrix in flow-based adhesion assays. Our studies demonstrate that the partial receptor complex (GPIb-IX) supports CHO cell tethering and rolling on a bovine or human vWf matrix under flow. The adhesion was specifically inhibited by an anti-GPIbalpha blocking antibody (AK2) and was not observed with CHO cells expressing GPIbbeta and GPIX alone. The velocity of rolling was dependent on the level of shear stress, receptor density, and matrix concentration and was not altered by the presence of GPV. In contrast to selectins, which mediate cell rolling under conditions of low shear (20-200 s-1), GPIb-IX was able to support cell rolling at both venous (150 s-1) and arterial (1500-10,500 s-1) shear rates. Studies with a mutant GPIbalpha receptor subunit lacking the binding domain for actin-binding protein demonstrated that the association of the receptor complex with the membrane skeleton is not essential for cell tethering or rolling under low shear conditions, but is critical for maintaining adhesion at high shear rates (3000-6000 s-1). These studies demonstrate that the GPIb-IX complex is sufficient to mediate cell rolling on a vWf matrix at both venous and arterial levels of shear independent of other platelet adhesion receptors. Furthermore, our results suggest that the association between GPIbalpha and actin-binding protein plays an important role in enabling cells to remain tethered to a vWf matrix under conditions of high shear stress.  (+info)

Activation of G12/G13 results in shape change and Rho/Rho-kinase-mediated myosin light chain phosphorylation in mouse platelets. (8/11030)

Platelets respond to various stimuli with rapid changes in shape followed by aggregation and secretion of their granule contents. Platelets lacking the alpha-subunit of the heterotrimeric G protein Gq do not aggregate and degranulate but still undergo shape change after activation through thromboxane-A2 (TXA2) or thrombin receptors. In contrast to thrombin, the TXA2 mimetic U46619 led to the selective activation of G12 and G13 in Galphaq-deficient platelets indicating that these G proteins mediate TXA2 receptor-induced shape change. TXA2 receptor-mediated activation of G12/G13 resulted in tyrosine phosphorylation of pp72(syk) and stimulation of pp60(c-src) as well as in phosphorylation of myosin light chain (MLC) in Galphaq-deficient platelets. Both MLC phosphorylation and shape change induced through G12/G13 in the absence of Galphaq were inhibited by the C3 exoenzyme from Clostridium botulinum, by the Rho-kinase inhibitor Y-27632 and by cAMP-analogue Sp-5,6-DCl-cBIMPS. These data indicate that G12/G13 couple receptors to tyrosine kinases as well as to the Rho/Rho-kinase-mediated regulation of MLC phosphorylation. We provide evidence that G12/G13-mediated Rho/Rho-kinase-dependent regulation of MLC phosphorylation participates in receptor-induced platelet shape change.  (+info)

Circulating platelets consist of subpopulations with different age, maturation state and size. In this review, we address the association between platelet size and platelet function and summarize the current knowledge on platelet subpopulations including reticulated platelets, procoagulant platelets and platelets exposing signals to mediate their clearance. Thereby, we emphasize the impact of platelet turnover as an important condition for platelet production in vivo. Understanding of the features that characterize platelet subpopulations is very relevant for the methods of platelet concentrate production, which may enrich or deplete particular platelet subpopulations. Moreover, the concept of platelet size being associated with platelet function may be attractive for transfusion medicine as it holds the perspective to separate platelet subpopulations with specific functional capabilities.
OBJECTIVE-The goal of this study was to specifically estimate the effectiveness of platelet releasate, a widely available treatment administered by a proprietary group of wound care centers (WCCs) for the treatment of diabetic neuropathic foot ulceration.. RESEARCH DESIGN AND METHODS-Treatment effectiveness was estimated in a retrospective cohort study controlling for treatment selection bias using logistic regression-derived propensity scores.. RESULTS-Platelet releasate was more effective than standard care. The relative risk for a wound to heal after treatment with platelet releasate compared with standard care at a WCC varied from 1.14 (95% CI 1.03-1.27) to 1.59 (1.49-1.70). The effect was greatest in those with the most severe wounds, i.e., large wounds that affect deeper anatomical structures.. CONCLUSIONS-Within the limitations of the ability of propensity score analysis to control for selection bias, platelet releasate is more effective than standard therapy. This effect is more ...
In this study, we show that the platelet surface expression of glycoprotein (GP) V is regulated by two independent mechanisms. While confirming that both thrombin and neutrophil elastase proteolyse GPV, we show that neutrophil cathepsin G, thrombin receptor activating peptide (TRAP), and a combination of ADP and epinephrine can each result in a decrease in the platelet surface expression of GPV by a nonproteolytic mechanism: a cytoskeletal-mediated redistribution of platelet surface GPV to the surface-connected canalicular system (SCCS). Four independent lines of evidence documented the nonproteolytic nature of this decrease in the platelet surface expression of GPV. First, flow cytometric studies showed that cathepsin G, TRAP, and ADP/epinephrine decreased the platelet surface expression of GPV without changing the total platelet content of GPV. Second, immunoelectron microscopy directly demonstrated translocation of GPV from the platelet surface to the SCCS. Third, the cathepsin G-, TRAP-, and ADP
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TY - JOUR. T1 - Influence of rheologic changes and platelet-neutrophil interactions on cell filtration in sepsis. AU - Kirschenbaum, Linda A.. AU - Aziz, Mohammed. AU - Astiz, Mark E.. AU - Saha, Dhanonjoy C.. AU - Rackow, Eric C.. PY - 2000/1/1. Y1 - 2000/1/1. N2 - We examined the role of erythrocyte (red blood cell; RBC) aggregation and deformability, neutrophil (polymorphonuclear neutrophil; PMN) deformability, whole-blood viscosity, and platelet-neutrophil interactions on cell filtration in subjects who were critically ill with sepsis (CIS), critically ill noninfected subjects (CINS), and healthy controls (C). We assessed cell deformability by filtration through filters of 5-μm pore size. Whole blood, RBC, PMN, and combinations of PMN and RBC were studied. Viscometry was done on isolated RBC. Platelet-PMN interactions were assessed with monoclonal antibodies to CD41 and activated CD53 platelet receptors, and to CD66b PMN receptors. Filtration pressure (Pi) for CIS was significantly greater ...
Partial purification and characterization of serine protease activity in platelets and platelet releasates from patients with Quebec platelet disorder Conference Paper ...
Approach and Results-To model standard antiplatelet therapy, platelets were treated in vitro with aspirin, the P2Y12 receptor blocker prasugrel active metabolite, and aspirin plus prasugrel active metabolite. Different proportions of uninhibited platelets were then introduced. Light transmission aggregometry analysis demonstrated clear positive associations between proportions of drug-free platelets and percentage platelet aggregation in response to a range of platelet agonists. Using differential platelet labeling coupled with advanced flow cytometry and confocal imaging, we found aggregates formed in mixtures of aspirin-inhibited platelets and drug-free platelets were characterized by intermingled platelet populations. This distribution is in accordance with the ability of drug-free platelets to generate thromboxane A2 and so drive secondary platelet activation. Conversely, aggregates formed in mixtures of prasugrel active metabolite-inhibited or aspirin plus prasugrel active ...
Introduction: S100A1 is a member of the S100 family of calcium-binding proteins. S100A1 controls Ca2+ dynamics in cardiomyocytes and plays an important role in heart failure. S100A1 is also strongly expressed in mouse platelets, but its role in platelet biology has not been investigated.. Goal: To determine the role of S100A1 in platelet activation and thrombosis.. Methods and Results: Platelet activation in response to threshold levels of convulxin, a specific agonist for the collagen receptor GPVI, showed significantly increased activation of αIIbβ3 integrin and α-granule release in S100A1-deficient (SKO) platelets compared with wild-type (WT) platelets. Consistently, SKO platelets also showed a more robust aggregation response to convulxin and collagen. In contrast, SKO platelets responded normally to stimulation with PAR4 receptor-activating peptide or ADP. Adhesion of SKO platelets to collagen under flow conditions was not significantly different to that of WT platelets. However, we ...
Oxidized LDL and platelets play a central role in the pathogenesis of atherosclerosis and ischemic cardiovascular diseases. Lysophosphatidic acid (LPA) is a thrombogenic substance that accumulates in mildly-oxidized LDL and in human atherosclerotic lesions, and is responsible for the initial platelet activation, shape change, induced by mildly-oxidized LDL and extracts of lipid-rich atherosclerotic plaques (Siess et al., 1999 Proc Natl Acad Sci USA 1999). LPA directly induced platelet shape change in blood and platelet-rich plasma (PRP) obtained from all blood donors. Albumin was one of the main inhibiting factors of platelet shape change in plasma. Interestingly LPA, at concentrations slightly above plasma levels, induced platelet shape change and aggregation in blood. 1-alkyl-LPA (16:0) was almost 20-fold more potent than 1-acyl-LPA (16:0). LPA-stimulated platelet aggregation in blood and PRP was donor-dependent. LPA-induced aggregation in blood could be completely blocked by the ADP- ...
A method for determining platelet activation by utilizing numeric counts of platelets before a sample of platelets has been activated and after the activatable platelets are activated with a platelet activation agonist and using the difference between such counts as an, indication of the platelet activity of the sample. There is also disclosed a method for using the electronic impedance cell counting technique for determining platelet activation wherein EDTA is used as a preservative by counting the platelets in an EDTA preserved sample using an electronic impedance cell counting technique and subtracting from that number the number of platelets remaining after the activatable platelets in a second sample have been activated with a platelet agonist in the absence of EDTA and using that difference as a measure of platelet activity.
Most heart attacks and strokes are caused by blood clots (thrombi) that block the vasculature. Because disease-causing arterial thrombosis depends on blood platelets, platelet inhibitors such as aspirin and clopidogrel effectively decrease the risk of thrombosis; however, they also impair platelet-dependent hemostasis that staunches bleeding from wounds and can therefore produce excessive bleeding. Experimental studies show that a reduction in the number of platelets also inhibits thrombosis, but these treatments also interfere with platelet function. Because normal hemostasis requires that the platelet concentration remain within a physiological range in the circulation, we evaluated whether lowering the number of circulating platelets-but only to a value still within the normal range-by inhibiting platelet formation in the bone marrow inhibits acute thrombogenesis in baboons. We reduced the platelet count with an inhibitor against the megakaryocyte-promoting hormone thrombopoietin and then ...
human platelet receptor for type III collagen: MW 68-72 kDa; platelet receptor involved in platelet interaction with type III collagen, localized within platelet lipid rafts where it could interact with other platelet receptors for collagen (GP VI and alpha2beta1 integrin) for efficient platelet activation
Reuters) - Scientists have for the first time created blood platelet cells by reprogramming stem cells derived from adult cells, offering the potential for a renewable supply of the fragile blood component.. Researchers at the Center for iPS Cell Research and Application at Kyoto University in Japan presented data here at a meeting of the American Society of Hematology showing they were able to create the cells in the laboratory and confirm they had the same life span as normal human platelets when infused in mice.. The next step will be to conduct a trial to determine whether our platelets can function in the human body and potentially provide a stable supply of platelets at a predefined quality and quantity that can then be used for transfusion therapy, D. Koji Eto, professor at the Kyoto center and senior author of the study, said in a statement.. Induced pluripotent stem cells, or iPS cells, are produced by manipulating ordinary human skin or blood cells back to a state in which they are ...
inbook{d2d8fceb-9b60-4916-ad95-3b1f6f9113f7, abstract = {,p,Many pathogenic bacteria have been reported to interact with human platelets to mediate platelet activation and aggregation. The importance of these interactions to the immune response or pathogenesis of bacterial infection has not been clarified. It may therefore be valuable to assess platelet responses mediated by diverse strains of bacteria. Here, I describe a method to study platelet integrin activation and granule release using flow cytometry, and a complementary method to study platelet aggregation using a dedicated platelet aggregometer. The combination of these methods represents a rapid and cost-effective strategy to provide mechanistic insight on the type of platelet response mediated by the bacteria.,/p,}, author = {Shannon, Oonagh}, issn = {10643745}, keyword = {Bacteria,Coagulation,Flow cytometry,Platelets,Streptococci}, language = {eng}, pages = {267--273}, publisher = {Humana Press}, series = {Methods in Molecular ...
The present study demonstrates that in type 2 DM patients with CAD receiving maintenance aspirin and clopidogrel therapy, the presence of moderate/severe CKD is associated with higher degrees of platelet reactivity compared with patients with normal renal function/mild CKD. In particular, after adjustment for potential confounders, patients with creatinine clearance ,60 ml/min had an almost 4-fold increase in the likelihood of showing high platelet reactivity after ADP stimuli and over a 2-fold increase in high platelet reactivity after collagen stimuli. Importantly, these patients with high platelet aggregability also have increased markers of platelet activation. Overall, these findings are indicative not only of dysfunctional purinergic signaling mediated ADP receptors but also of the presence of a hyper-reactive platelet phenotype with upregulation of multiple signaling pathways. Therefore, these pharmacodynamic observations might explain the elevated prevalence of ischemic complications, ...
OBJECTIVE-: Protease-activated receptor 4 (PAR4) is a key regulator of platelet reactivity and is encoded by F2RL3, which has abundant rare missense variants. We aimed to provide proof of principle that rare F2LR3 variants potentially affect on platelet reactivity and responsiveness to PAR1 antagonist drugs and to explore underlying molecular mechanisms. APPROACH AND RESULTS-: We identified 6 rare F2RL3 missense variants in 236 cardiac patients, of which the variant causing a tyrosine 157 to cysteine substitution (Y157C) was predicted computationally to affect most on PAR4 structure. Y157C platelets from 3 cases showed reduced responses to PAR4-activating peptide and to α-thrombin compared with controls, but no reduction in responses to PAR1-activating peptide. Pretreatment with the PAR1 antagonist vorapaxar caused lower residual α-thrombin responses in Y157C platelets than in controls, indicating greater platelet inhibition. HEK293 cells transfected with a PAR4 Y157C expression construct had ...
TY - JOUR. T1 - Four types of human platelet lysate, including one virally inactivated by solvent-detergent, can be used to propagate Wharton jelly mesenchymal stromal cells. AU - Chen, Ming Sheng. AU - Wang, Tsung Jen. AU - Lin, Hsiu Chen. AU - Thierry, Burnouf. PY - 2019/3/25. Y1 - 2019/3/25. N2 - There is accumulating experimental evidence that human platelet lysate (HPL) made from platelet concentrates can replace fetal bovine serum (FBS) as a xeno-free clinical-grade supplement of growth media to expand mesenchymal stromal cells (MSCs). However, uncertainties exist in regard to impacts that various manufacturing methods of HPL can exert on the expansion and differentiation capacity of MSCs. In particular, there is a need to evaluate the possibility of implementing virus-inactivation treatment during HPL production to ensure optimal safety of industrial HPL pools. Expired human platelet concentrates from four different donors were pooled and subjected to freeze-thaw cycles (-80/+37 °C), ...
The typical reconstruction model of an unstimulated human platelet is presented. It shows a strict spatial order of organelles and enodmembrane systems. The surface-connected vesicle system is predominantly found in the periphery. The dense tubules constitute a continuous, interconnected system found just under the surface of the platelet. They are particularly pronounced in the vicinity of the marginal microtubules. All organelles are in contact with the dense tubular system (DTS). Granules, vesicles and plasmalemma fuse into the tubules. The platelet organelles are centrally located. Lysosomal granules are primarily shperical and all of them contain a nucleoid. This speaks in favor of a single type of storage organelle in the platelet. The dense bodies and their remnants (large, solitary vesicles) are not joined by the other endomembrane systems, as in the case of the granules. A particular pathways for the release of substances from these organelles is now morphologically plausible. Mitochondria are
TY - JOUR. T1 - Platelet function after cardiac surgery and its association with severe postoperative bleeding. T2 - the PLATFORM study. AU - for The Surgical and Clinical Outcome Research (SCORE) Group. AU - Ranucci, Marco. AU - Pistuddi, Valeria. AU - Di Dedda, Umberto. AU - Menicanti, Lorenzo. AU - De Vincentiis, Carlo. AU - Baryshnikova, Ekaterina. PY - 2018/1/1. Y1 - 2018/1/1. N2 - Platelet dysfunction after cardiac surgery is a determinant of postoperative bleeding. The existing guidelines suggest the use of desmopressin and/or platelet concentrate transfusions in case of platelet dysfunction in bleeding patients, but no cut-off values for platelet activity exist in the literature. The Platelet Function in the Operating Room (PLATFORM) study aims to identify the relationship between platelet function after cardiopulmonary bypass and severe bleeding, finding adequate predictive values of platelet function for severe bleeding. The PLATFORM is a prospective cohort study on 490 adult patients ...
The frequency and severity of bacteremic infections has increased over the last decade and bacterial endovascular infections (i.e., sepsis or endocarditis) are associated with high morbidity and mortality. Bacteria or secreted bacterial products modulate platelet function and, as a result, affect platelet accumulation at sites of vascular infection and inflammation. However, whether bacterial products regulate synthetic events in platelets is not known. In the present study, we determined if prolonged contact with staphylococcal α-toxin signals platelets to synthesize B-cell lymphoma (Bcl-3), a protein that regulates clot retraction in murine and human platelets. We show that α-toxin induced αIIbβ3-dependent aggregation (EC50 2.98 µg/mL ± 0.64 µg/mL) and, over time, significantly altered platelet morphology and stimulated de novo accumulation of Bcl-3 protein in platelets. Adherence to collagen or fibrinogen also increased the expression of Bcl-3 protein by platelets. α-toxin altered Bcl-3
Methods were developed for measuring changes in platelet sensitivity to a release-inducing stimulus and in platelet cyclic AMP in fresh whole blood samples from rabbits. These techniques permitted detection of the effects of exogenous and endogenous prostacyclin on circulating platelets. In these methods, rabbit platelets were labeled in vitro by incubation with [14C]serotonin and [3H]adenine and then transfused into other rabbits. Release of platelet [14C]serotonin by a standard dose of synthetic platelet-activating factor (40 pmol/ml) and the platelet cyclic [3H]AMP levels were then measured in citrated blood from the conscious animals within 2 min of arterial puncture. Bolus intravenous injections of prostacyclin (1-10 nmol/kg) caused concentration-dependent increases in platelet cyclic AMP after 2 min, which decreased approximately 75% by 5 min, and disappeared after 30 min. Significant inhibition of the platelet release reaction was detected 2 min but not 5 min after injection of 10 nmol of ...
TY - JOUR. T1 - Transfection of human platelets with short interfering RNA. AU - Hong, Wei. AU - Kondkar, Altaf A.. AU - Nagalla, Srikanth. AU - Bergmeier, Wolfgang. AU - Jin, Ying. AU - Herman, Jay H.. AU - Bray, Paul F.. PY - 2011/6. Y1 - 2011/6. N2 - Platelets contain mRNAs and are capable of translating mRNA into protein, and it has been previously demonstrated that platelets increase their levels of integrin β3 overtime while in blood bank storage conditions. We are unaware of prior attempts to introduce nucleic acids into platelets. Considering the potential clinical and research utility of manipulating platelet gene expression, we tested whether small interfering RNAs (siRNAs) could be transfected into normal human platelets. Multiple conditions were tested, including lipofectamine versus electroporation, different amounts of siRNA, the effect of different buffers and the presence of plasma during transfection, and the time for optimal siRNA incorporation after transfection. Using flow ...
Release: Dec. 3, 1999. UI participates in multi-center study testing new platelet sterilizing strategy. IOWA CITY, Iowa The University of Iowa Hospitals and Clinics is participating in a multi-center trial testing the efficacy and safety of a new way to cleanse infectious organisms from donated platelets before the blood product is administered to patients.. The UI department of pathology has received a one-and-half-year grant from health care companies Baxter and Cerus for the study titled Determination of the therapeutic efficacy and safety of photochemically treated platelets in thrombocytopenic patients.. Thrombocytopenia is a condition characterized by low blood platelet counts. Platelets are the clotting particles in blood.. The new photochemical strategy attempts to sterilize donated platelets against bacteria and viruses, which may be present in blood products. The goal of the study is to establish that the platelets are not damaged from the sterilization process. Preliminary data ...
The TEMPLATE study design will enable unbiased comparison of the effects of TIC versus TIC + ASP on platelet activity in patients with coronary artery disease. It will also enable a longitudinal comparison of the effects TIC and TIC + ASP with the effects of ASP alone in the same patients. The laboratory tests selected for this study will enable measurement of functional platelet responses to a panel of activating agonists using LTA, flow cytometry and flow chamber tests, selected to measure the extent of inhibition of the multiple platelet activation pathways. We will also measure the extent of baseline platelet activity by testing unstimulated platelets by flow cytometry and with the soluble platelet activation biomarker tests. Together, these data will provide a comprehensive description of the overall pharmacodynamic effects of the different antiplatelet treatments. This information has not been reported previously in cohorts of patients with coronary artery disease receiving TIC or TIC + ...
Blood platelets commonly called megakaryocytes are one of the three tiny cellular components of the blood which helps in the stoppage of bleeding.. Other cellular components of blood are the red blood cells and white blood cells. All the cellular components bathe in the plasma.. Nearly half a billion blood platelets are being formed in the bone marrow every day. These play a primary role in the formation of blood clot. Here I would like to define the two common terms related to the platelet plug formation when the blood vessel in injured.. * Adhesion means sticking of blood platelets with the wall of the bleeding vessel.. * Aggregation means sticking of the platelets with each other.. Normally, in the circulating blood, platelets keep on flowing without any adhesion or aggregation. However, injury to the wall of blood vessel is the point when blood platelets start clinging to the injured part of the vessel wall. At the same time the platelets aggregate with one another and completely seal the ...
The normal circulating platelet count is maintained within relatively narrow limits (150,000-450,000 platelets/μL in Northern Europeans and 90,000-300,000 platelets/μL in people of Mediterranean descent). This difference is related to an inherited slight variation in individual platelet volume (size). The platelet volume is inversely related to the platelet count, so the mass of circulating platelets is the same for these 2 populations. Approximately one-third of platelets are sequestered in the spleen at any one time. Splenic sequestration of platelets can increase dramatically with splenomegaly. Since a platelet has a lifespan of approximately 9-10 days, some 15,000-45,000 platelets/μL must be produced each day to maintain a steady state. New platelet production is the responsibility of the megakaryocyte, a very large multinucleated cell (10,750 fL) found in relatively small numbers in the marrow (0.1% of marrow cells) (Figure 31-1). As with other hematopoietic cells, megakaryocytes are ...
Research in the Laboratory for Hemostasis and Platelet Biology, led by Dr. Andrew Johnson, focuses on understanding genetic and genomic underpinnings of this individual variability in therapeutically targeted CVD pathways ...
Although tumor dormancy is highly prevalent, the underling mechanisms are still mostly unknown. It is unclear which lesions will progress and become a disseminated cancer, and which will remain dormant and asymptomatic. Yet, an improved ability to predict progression would open the possibility of timely treatment and improvement in outcomes. We have recently described the ability of platelets to selectively uptake angiogenesis regulators very early in tumor growth, and proposed their use as an early marker of malignancy. In this review we will summarize current knowledge about these processes and will discuss the possibility of using platelet content to predict presence of occult tumors.
OBJECTIVES: We sought to examine whether patients with stable coronary artery disease (CAD) have increased platelet reactivity and an enhanced propensity to form monocyte-platelet aggregates. BACKGROUND: Platelet-dependent thrombosis and leukocyte infiltration into the vessel wall are characteristic cellular events seen in atherosclerosis. METHODS: Anticoagulated peripheral venous blood from 19 patients with stable CAD and 19 normal control subjects was incubated with or without various platelet agonists and analyzed by whole blood flow cytometry. RESULTS: Circulating degranulated platelets were increased in patients with CAD compared with control subjects (mean [+/- SEM] percent P-selectin-positive platelets: 2.1 +/- 0.2 vs. 1.5 +/- 0.2, p andlt; 0.01) and were more reactive to stimulation with 1 micromol/liter of adenosine diphosphate (ADP) (28.7 +/- 3.9 vs. 16.1 +/- 2.2, p andlt; 0.01), 1 micromol/liter of ADP/epinephrine (51.4 +/- 4.6 vs. 37.5 +/- 3.8, p andlt; 0.05) or 5 micromol/liter of thrombin
Our data clearly show that human platelets can both bind and degrade full-length rhTPO. The affinity constants derived from the binding data indicate that rhTPOs affinity for platelet receptors was similar to that for the cloned c-Mpl receptor construct, gD-Mpl. The binding constants were also similar for rhTPO binding to PRP at 37°C and WP at 22°C. These data show that platelets bind rhTPO, likely via c-Mpl with high affinity (∼350 pmol/L), and that this binding is saturable. Scatchard analysis predicted a low number of (∼23 to 224) binding sites per platelet. However, this estimate may be low, because c-Mpl binding sites on circulating platelets are likely partially occupied by endogenous circulating TPO.9,10 If we assume the number of available c-Mpl receptors is ∼25 to 200 per platelet and that the approximate number of platelets per liter of blood in humans is 200 × 109, then the predicted binding capacity would be ∼8 to 64 pmol per liter of blood. This approximation suggests ...
Subjects for all study groups will be male and between the ages of 25 and 65. Hypertension & Depression Group: Hypertension controlled with an ACE-inhibitor anti-hypertensive; no co-morbid medical conditions known to influence psychological functioning or platelet calcium responses including uncontrolled diabetes, MI or CVA within 6 months of enrollment, secondary hypertension; depression as diagnosed by structured interview and HDRS score of 18; no active participation in another clinical trial; no current suicidal/ homicidal ideation. Hypertension Group: Hypertension controlled with an ACE-inhibitor anti-hypertensive; no co-morbid medical conditions known to influence psychological functioning or platelet calcium responses including uncontrolled diabetes, MI or CVA within 6 months of enrollment, secondary hypertension; no active participation in another clinical trial; no current suicidal/ homicidal ideation. Depression Group: No co-morbid medical conditions known to influence psychological ...
Platelets may interact directly with their targets and perform its killing function. For example, platelets may bind and wrap bacteria (Youssefian et al., 2002) or induce their aggregation (OBrien et al., 2002), leading to degranulation. During malaria infection, platelets have also been described to perform the direct killing of plasmodium parasites in their blood stage forms in a PF4-dependent manner (McMorran et al., 2009, 2012), leading to the general perception that platelets play protective roles during an infection. However, a recent in vivo study in mice paradoxically found that platelet depletion did not lead to higher parasitemia levels (Gramaglia et al., 2017). Instead, links were found between the presence of platelets and malarial pathogenesis via CD40 interactions. Because about two thirds (Jadhav et al., 2004) of malarial infections are accompanied by thrombocytopenia, it thus remains a quandary for clinicians to decide if they should be boosting or inhibiting platelet function ...
1. A new fixing solution is described, which preserves the platelets and prevents contact hemolysis of the erythrocytes, so that counts of both corpuscles may be made in the same preparation.. 2. Comparative counts of platelets in arteries and veins show that arterial blood contains a larger number of platelets than venous blood. This difference is accentuated under experimental conditions that cause a reduction in the number of platelets. It is concluded that new platelets are added to the blood in the capillary areas of the lungs, and that there is a corresponding destruction of platelets as the blood passes through the capillary areas of the systemic circulation.. 3. Perfusion of the lungs with a platelet-preserving solution, compared with that of other organs, gives evidence of the existence of a source of platelet material in the lungs.. 4. Histological examination of the lungs with a technique adequate to give a differential staining of platelet material demonstrates the presence of giant ...
New studies in mice suggest that blood platelets can destroy deadly malaria parasites, but a single dose of aspirin may be enough to thwart their killing power., , , , The findings could have important im...
ANTICOAGULANTS AND THROMBOLYTIC DRUGSHaemostasisVascular injury results firstly in vasoconstriction and formation of platelet plug at the site of injury (primary haemostasis). The platelet plug is then stabilized by the formation of a fibrin meshwork, resulting from activation of the coagulation cascade.Fibrin is eventually cleared through digestion by fibrinolytic enzymes.Primary HaemostasisWhen endothelial integrity is breached, platelets adhere to exposed subendothelial collagen. The adherent platelets become activated result in;1) Exposure of fibrinogen receptors, allowing fibrinogen to bind and cross-link adjacent platelets. The process is known as platelet aggregation. The platelet fibrinogen receptor consists of a complex of glycoproteins IIb and IIIa on the platelet membrane.2) Release of contents of secretory granules including substances such as adenosine diphosphate (ADP) which promote further platelet activation.3) Synthesis of thromboxane A2 which also acts to promote further ...
AimsTo assess whether platelet reactivity is increased in offspring of patients with early acute myocardial infarction (AMI) and its possible relation with endothelial dysfunction.Methods and resultsWe studied 23 healthy children (15 ± 3 years, 13 males) of patients with early AMI (≤50 years old; Group 1) and 21 healthy children of healthy subjects without any history of cardiovascular disease (14 ± 3 years, 10 males; Group 2). Platelet reactivity was assessed by flow cytometry as the increase in monocyte-platelet aggregates (MPA) and CD41 and PAC-1 platelet expression in response to exercise stress test (EST), adenosine diphosphate (ADP) stimulation (10 -7 M), or both. Endothelial function was assessed by measuring brachial artery dilation during post-ischaemic forearm hyperaemia [flow-mediated dilation (FMD)]. Both EST and ADP induced a higher percentage increase in platelet receptor expression in Group 1, compared with Group 2, with the most significant difference being shown for the ...
As conventional tissue biopsies have several drawbacks, much effort has been directed toward the development of minimal-invasive liquid biopsy platforms for detecting and profiling cancer.. Platelets are the second most abundant cells in blood and have very versatile functions both in physiological and pathophysiological conditions. When exposed to tumors and their environment, platelets exchange biomolecules with tumor cells changing the platelets RNA profile, resulting in tumor-mediated education of the platelets. Our research group and collaborators have previously shown that platelets sequester material while in circulation and with that ability accumulate cancer specific information. Platelet RNA profiles or detection of tumor-derived biomarkers within them may provide insight into ongoing cancer-related processes in a patient, allowing for implementation of personalized therapy strategies.. This thesis evaluates whether circulating platelets could have a potential role (as a liquid biopsy ...
Platelets, also called thrombocytes (thromb- + -cyte, blood clot cell), are a component of blood whose function (along with the coagulation factors) is to stop bleeding by clumping and clotting blood vessel injuries. Platelets have no cell nucleus: they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, and then enter the circulation. These unactivated platelets are biconvex discoid (lens-shaped) structures, 2-3 µm in greatest diameter. Platelets are found only in mammals, whereas in other animals (e.g. birds, amphibians) thrombocytes circulate as intact mononuclear cells. On a stained blood smear, platelets appear as dark purple spots, about 20% the diameter of red blood cells. The smear is used to examine platelets for size, shape, qualitative number, and clumping. The ratio of platelets to red blood cells in a healthy adult is 1:10 to 1:20. The main function of platelets is to contribute to hemostasis: the process of stopping bleeding at the site of ...
After deposition of a platelet monolayer over the exposed VWF and collagen, the next step required for thrombus formation is the recruitment of additional platelets from the flowing blood, which upon activation acquire the ability to stick to each other in a process commonly referred to as platelet aggregation. This is made possible by the local accumulation of soluble agonists that are secreted/produced by adherent-activated platelets, including ADP, TxA2, epinephrine and thrombin. The final step is activation of αIIbβ3, causing a conformational change that enables it to bind fibrinogen and VWF, allowing stable bridges between platelets. The great number of αIIbβ3 copies on the platelet surface, (40,000-80,000), allows the assembly of large aggregates at the site of vascular injury. Activation of αIIbβ3 integrin requires agonist-driven activation events in recruited platelets, referred to as inside-out signaling, including the sequential activation of one or more PLC isoforms yielding a ...
Fig.10 Design of CREKA-Lipo-T nanoparticles and their proposed antimetastatic mechanism within tumor tissues. (A) Proposed mechanism of action of CREKA-Lipo-T nanoparticles. Normally, tumor growth factor (TGF)-b secreted by platelets induces transition of tumor cells to a mesenchymal-like phenotype (I). Platelets can also protect tumor cells against attack from natural killer (NK) cells (II). At distant sites, platelets assist metastatic cells to cross the local endothelium by secreting numerous cytokines. Following treatment, CREKA-Lipo-T actively targets microthrombi in tumor vessel walls and releases ticagrelor slowly and locally. Ticagrelor binds to tumor-associated platelets and inhibits their functions. The release of TGF-b from platelets and the interaction between platelets and tumor cells are abolished, leading to decreased epithelial-mesenchymal-like transition of tumor cells and thus inhibiting their invasion capacity. When tumor cells are present in circulation, compromised platelets ...
TY - JOUR. T1 - Preferential binding of platelets to monocytes over neutrophils under flow. AU - Ahn, Kyung C.. AU - Jun, Andy J.. AU - Pawar, Parag. AU - Jadhav, Sameer. AU - Napier, Susan. AU - McCarty, Owen J.T.. AU - Konstantopoulos, Konstantinos. PY - 2005/4/1. Y1 - 2005/4/1. N2 - This study was undertaken to systematically investigate the binding kinetics of platelet recruitment by monocytes relative to neutrophils in bulk suspensions subjected to shear as well as the molecular requirements of leukocyte-platelet binding. Hydrodynamic shear-induced collisions augment the proportion of monocytes with adherent platelets more drastically than that of neutrophils with bound platelets. These heterotypic interactions are further potentiated by platelet activation with thrombin or to a lesser extent by monocyte stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP). Monocyte-platelet heteroaggregation increases with increasing shear rate and shear exposure time. Platelet P-selectin ...
Cooper, N., Heddle, N. M., de Haas, M., Reid, M. E., Lesser, M. L., Fleit, H. B., Woloski, B. M. R. and Bussel, J. B. (2004), Intravenous (IV) anti-D and IV immunoglobulin achieve acute platelet increases by different mechanisms: modulation of cytokine and platelet responses to IV anti-D by FcγRIIa and FcγRIIIa polymorphisms. British Journal of Haematology, 124: 511-518. doi: 10.1111/j.1365-2141.2004.04804.x ...
Tortuous blood vessels are often seen in humans in association with thrombosis, atherosclerosis, hypertension, and aging. Vessel tortuosity can cause high fluid shear stress, likely promoting thrombosis. However, the underlying physical mechanisms and microscale processes are poorly understood. Accordingly, the objectives of this study were to develop and use a new computational approach to determine the effects of venule tortuosity and fluid velocity on thrombus initiation. The transport, collision, shear-induced activation, and receptor-ligand adhesion of individual platelets in thrombus formation were simulated using discrete element method. The shear-induced activation model assumed that a platelet became activated if it experienced a shear stress above a relative critical shear stress or if it contacted an activated platelet. Venules of various levels of tortuosity were simulated for a mean flow velocity of 0.10 cm s−1 , and a tortuous arteriole was simulated for a mean velocity of 0.47 ...
Article see p 476. As megakaryocytes form platelets, they transfer STAT3 to proplatelet tips. Consequently, STAT3 is found in platelets that circulate in the bloodstream (Figure). The presence of STAT3 in platelets raises the question of whether it regulates functional responses in platelets or is simply a vestigial remnant of megakaryocytes. An argument for the leftover without function hypothesis is the anucleate status of platelets: simply stated, with no nucleus and no nuclear DNA there is no place for STAT3 to stick in platelets. The problem with this argument is that simple is no longer a common word used to describe platelets. Moreover, why would platelets expend energy to carry a protein that they do not need, especially since previous studies have shown that STAT3 undergoes signal-dependent phosphorylation in these anucleate cytoplasts?4 Well, any doubt regarding why STAT3 is present in platelets has been cleared up. Using a combination of pharmacological and genetic based tools, ...
Majid Ali, M.D. Children are invited to use the text and photographs (such as those below) on this web site for preparing competition essays and school science projects. Blood Platelet Clump Due to Oxidative Stress. Dissociation of Platelet Aggregates by Vitamin C Figure 15 (top) shows patterns of aggregation of platelets induced by…
Background: Coated-platelets, a subset of activated platelets observed with dual-agonist stimulation with collagen and thrombin, represent 30% of the platelet population in normal controls. In recently published work, we have shown that elevated coated-platelet levels (,45%) are predictive of stroke in asymptomatic carotid stenosis. We now investigate if platelet count and mean platelet volume (MPV) are related to coated-platelet levels.. Methods: Coated-platelet levels were measured in a cohort of asymptomatic outpatients referred for carotid ultrasound studies. Platelet count and mean platelet volume for each subject were recorded from the VA electronic medical record at the closest possible time period (within ≤6 months) to the date of coated-platelet sample. Correlations between each parameter and coated-platelet levels were determined and those reaching significance at p≤0.1 were included in a multiple regression model with LDL and systolic blood pressure (SBP), variables previously ...
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TY - JOUR. T1 - A study of whole blood platelet and white cell aggregation using a laser flow aggregometer. AU - Sun, J.. AU - Abel, E. W.. AU - Bancroft, A.. AU - McLaren, M.. AU - Belch, J. J. F.. PY - 2003. Y1 - 2003. N2 - Both platelet aggregation and white blood cell aggregation are involved in pathological processes such as thrombosis, atherosclerosis and chronic inflammation. People in older age groups are likely to suffer from cardiovascular diseases and may have increased white cell and platelet aggregation which could contribute to this increased risk. This study aimed to compare white cell and platelet aggregation between different age and gender groups. Whole blood white cell aggregation and platelet aggregation were carried out on healthy volunteers using cytometric techniques. It was found that both white cell and platelet aggregation in the elderly group (white cell aggregation median value, 0.08; range, 0.02-0.14; platelet aggregation median value, 0.32; range, 0.1-0.39) were ...
Systematic review (Open Access) on the comparison of different platelet transfusion thresholds prior to insertion of central lines in patients with thrombocytopenia from Cochrane Database of Systematic Reviews Comparison of different platelet transfusion thresholds prior to insertion of central lines in patients with thrombocytopenia #vascularaccess #FOAMva #FOAMed #FOAMcc #POCUS #patientsafety
Megakaryocytes generate platelets by remodeling their cytoplasm into long proplatelet extensions, which serve as assembly lines for platelet production. Although the mechanics of proplatelet elongation have been studied, the terminal steps of proplatelet maturation and platelet release remain poorly understood. To elucidate this process, released proplatelets were isolated, and their conversion into individual platelets was assessed. This enabled us to (a) define and quantify the different stages in platelet maturation, (b) identify a new intermediate stage in platelet production, the preplatelet, (c) delineate the cytoskeletal mechanics involved in preplatelet/proplatelet interconversion, and (d) model proplatelet fission and platelet release. Preplatelets are anucleate discoid particles 2-10 \(\mu\)m across that have the capacity to convert reversibly into elongated proplatelets by twisting microtubule-based forces that can be visualized in proplatelets expressing GFP-\(\beta\)1-tubulin. The ...
In patients with thrombocytopenia, it can be difficult to predict a patients bleeding risk based on platelet count alone. Platelet reactivity may provide additional information; however, current clinical assays cannot reliably assess platelet function in the setting of thrombocytopenia. New methods to study platelet reactivity in thrombocytopenic samples are needed. In this study, we sought to develop a laboratory model of thrombocytopenia using blood from healthy subjects that preserves the whole blood environment and reproducibly produces samples with a specific platelet count and hematocrit. We compared the activation state of unstimulated and agonist-stimulated platelets in thrombocytopenic samples derived from this method with normocytic controls. Whole blood was diluted with autologous red blood cell concentrate and platelet-poor plasma, which were obtained via centrifugation, in specific ratios to attain a final sample with a predetermined platelet count and hematocrit. P-selectin exposure and
With platelet activation, there is modulation of platelet surface molecule expression. In flow cytometric analyses of in vivo platelet activation, results are often confounded by activation induced in vitro by the preparative procedures. It is particularly important therefore to prevent or retard platelet activation as soon as possible after withdrawal of the blood sample. Taking blood into paraformaldehyde, or fixing the cells with paraformaldehyde as soon as possible after withdrawal, has been employed to prevent platelet activation in vitro, but paraformaldehyde-fixed platelets cannot be further used in functional studies. We investigated the efficacy of Diatube-H, a commercially available combination of platelet antagonists (theophylline, adenosine, and dipyridamole), in preventing or retarding platelet activation in vitro, along with its effects on modulation of platelet membrane glycoproteins (GP) and adhesion molecules. In contrast to blood taken into EDTA, blood taken into Diatube-H ...
The present study clarifies several aspects of the effects on platelet aggregation of arising and assuming the upright posture in the morning: 1) On arising, increased platelet aggregation can readily be observed in whole blood; 2) this increased aggregation is not accompanied by platelet activation, as evidenced by changes in activation-dependent markers on the platelet surface; 3) the observed increase in aggregation in whole blood may be partly explained by increases in platelet count and hematocrit that accompany arising. In addition, the study confirmed previous reports of increased fibrinolysis on standing and provided new evidence of an opposing increase in thrombin generation on standing.. Comparison with previous studies. Studies reporting the effects of arising in the morning on platelet aggregation (7-11,13) have exclusively studied aggregation in PRP, and to our knowledge, the present study is the first to report the effects of arising on platelet aggregation in whole blood. Of the ...
FIG. 2. Cleavage of α2-8-linked sialic acid from platelet surfaces results in a reduction of S. mitis binding. Binding of SF100 (□) to untreated human platelets (lane 1) or platelets pretreated with sialidase A (lane 2), sialidase V (lane 3), or sialidase C (lane 4). Binding of PS344 (▪) to platelets (lane 5) or platelets pretreated with sialidase A (lane 6), sialidase V (lane 7), or sialidase C (lane 8). Values presented are expressed as a percentage of wild-type binding to untreated platelets (mean ± SD). Data represent three experiments performed in triplicate on different occasions from a different donor each time. Note that these donors are different from those shown in Fig. 1. ...
Normal primary platelet aggregation requires agonist-mediated activation of membrane GPIIb-IIIa, binding of fibrinogen to GPIIb-IIIa, and cellular events after ligand binding. PAC1 monoclonal antibody distinguishes between resting and activated states of GPIIb-IIIa, and other antibodies preferentially recognize GPIIb (PMI-1) or IIIa (anti-LIBS1) after the binding of fibrinogen or fibrinogen-mimetic peptides, such as GRGDSP. Using these antibodies and platelet flow cytometry, we studied two distinct persistent platelet aggregation abnormalities. Platelets from a thrombasthenic variant, which contained near-normal amounts of GPIIb-IIIa, failed to aggregate or bind PAC1 in response to agonists. In addition, GRGDSP, which binds to normal GPIIb-IIIa without prior cell activation, failed to increase the binding of PMI-1 or anti-LIBS1 to the thrombasthenic platelets, suggesting a primary defect in ligand binding. Chromatography of detergent-solubilized platelets on a KYGRGDS affinity column confirmed ...
Platelets are cell fragments which are mainly an essential component when it comes to blood clotting and coagulation. The platelets along with the red blood cells and white blood cells, function together for the regulation and normal functioning of blood in our body. The blood cells have each of their own different life span as well as different functions. Among these three, the platelets are the smallest but one of the most important factors in blood clotting. If the platelets dont get regulated properly, such as when they dont get renewed at normal intervals, then the blood dysfunction or disorder might occur.. The general lifespan of a platelet is about 10 days. The normal platelet count in the human blood ranges from 150,000 to 450,000 per micro liter of blood. The platelet count varies in different locations and organs. But in cases of medical conditions, the platelets count may either increase or decrease in the blood. One of the most common condition of platelet count changes is the ...
SUMMARY Acquired qualitative platelet disorders are frequent causes of abnormal platelet function measured in vitro, although by themselves are usually associated with little or no clinical bleeding. However, there are important exceptions. Nevertheless, their major clinical impact becomes apparent in the additional presence of thrombocytopenia, or additional acquired or congenital disorders of hemostasis. Acquired disorders of platelet function can be conveniently classified into those that result from drugs, hematologic diseases, and systemic disorders. Drugs are the most frequent cause of acquired qualitative platelet dysfunction. Aspirin is the most notable drug in this regard because of its frequent use, its irreversible effect on platelet prostaglandin synthesis, and its documented effect on hemostatic competency, although this effect is minimal in normal individuals. Other nonsteroidal antiinflammatory drugs reversibly inhibit platelet prostaglandin synthesis and usually have little ...
Platelets are an important blood component that helps in controlling bleeding. The most abundant particle in our blood is the platelet that causes the blood to clot whenever theres a cut or injury, thereby stopping the bleeding in minutes. Now, there are tens and thousands of platelets in normal which help in this process. But in cases of certain diseases and illness like dengue etc the platelets gets destroyed by the infective germ, making the body prone to bleeding. Such a low count of platelet can cause serious brain damage and other organ damage. Apart from a blood transfusion, the most trusted way to increase your platelet count is by eating low platelets treatment food. Foods to increase platelet count are often used as basic preventive care and home remedy for diseases like dengue. But how do these home remedies to increase platelets work is a very basic understanding of…. ...
A low blood platelet count, known as thrombocytopenia, prevents blood from clotting normally. This can be an indication of serious medical conditions.SignificanceThe three main reasons for a low blood platelet count include reduced platelet production at bone marrow, blockage of platelets at enlarged spleen and an overuse or elimination of platelets by the body.Conditions Affecting Bone MarrowHIV and cancers such as leukemia and lymphoma reduce the capacity of bone marrow to produce platelets.Conditions Affecting the SpleenMyelofibrosis and certain forms of cirrhosis can enlarge the spleen. This hinders the passage of platelets into the bl...
While the heterozygous Q43P β1-tubulin carriers have a reduced function, the β1-tubulin-deficient mice present with only minor abnormalities in platelet hemostatic functions. Besides the fact that human platelets are more easy to handle and study in detail than mouse platelets, this can probably be explained by the fact that the loss of β1-tubulin expression in mouse platelets was overcome by overexpression of the other platelet β-tubulin variants,7 while the Q43P carrier platelets not only show reduced β1-tubulin but also total β-tubulin protein levels. In addition, incorporation of GFP-tagged Q43P β1-tubulin into wild-type tubulin structures seems to be inefficient and delocalized.. Due to the platelet dysfunction phenotype, the Q43P β1-tubulin variant could not only be conceived as a genetic risk factor for the development of thrombocytopenia but also as a protective genetic factor against cardiovascular disease. Indeed, a case-control study showed that the prevalence of Q43P ...
Activated blood platelets mediate the primary response to vascular injury. Although molecular abnormalities of platelet proteins occur infrequently, taken collectively, an inherited platelet defect accounts for a bleeding diathesis in ≈1:20,000 individuals. One rare example of a platelet disorder, Glanzmann thrombasthenia (GT), is characterized by life-long morbidity and mortality due to molecular abnormalities in a major platelet adhesion receptor, integrin αIIbβ3. Transfusion therapy is frequently inadequate because patients often generate antibodies to αIIbβ3, leading to immunemediated destruction of healthy platelets. In the most severe cases allogeneic bone marrow transplantation has been used, yet because of the risk of the procedure it has been limited to few patients. Thus, hematopoietic stem cell gene transfer was explored as a strategy to improve platelet function within a canine model for GT. Bleeding complications necessitated the use of a mild pretransplant conditioning ...
Activation of platelets with thrombin and other agonists causes a rapid increase in the phosphorylation of multiple proteins on tyrosine. To identify candidate protein-tyrosine kinases (PTKs; EC 2.7.1.112) that may be responsible for these phosphorylation events, we analyzed the expression of seven Src-family PTKs and examined the association of these kinases with known platelet membrane glycoproteins. Five Src-related PTKs were detected in platelets: pp60SRC, pp60FYN, pp62YES, pp61HCK, and two LYN products of Mr 54,000 and 58,000. The Fgr and Lck PTKs were not detected. Although strict comparative quantification of protein levels was not possible, pp60SRC was detected at higher levels than any of the other kinases. In addition, glycoprotein IV (GPIV, CD36), one of the major platelet membrane glycoproteins, was associated in a complex with the Fyn, Yes, and Lyn proteins in platelet lysates. Similar complexes were also found in two GPIV-expressing cell lines, C32 melanoma cells and HEL cells. ...
Phosphatidylinositol 3-kinaseβ (PI3Kβ) plays a predominant role in integrin outside-in signaling and in platelet activation by GPVI engagement. We have shown that the tyrosine kinase Pyk2 mediates PI3Kβ activation downstream of integrin αIIbβ3, and promotes the phosphorylation of the PI3K-associated adaptor protein c-Cbl. In this study, we compared the functional correlation between Pyk2 and PI3Kβ upon recruitment of the two main platelet collagen receptors, integrin α2β1 and GPVI. PI3Kβ-mediated phosphorylation of Akt was inhibited in Pyk2-deficient platelets adherent to monomeric collagen through integrin α2β1, but occurred normally upon GPVI ligation. Integrin α2β1 engagement led to Pyk2-independent association of c-Cbl with PI3K. However, c-Cbl was not phosphorylated in adherent platelets, and phosphorylation of Akt occurred normally in c-Cbl-deficient platelets, indicating that the c-Cbl is dispensable for Pyk2-mediated PI3Kβ activation. Stimulation of platelets with CRP, a ...
Angiotensin II (Ang II) is a critical component of the reninangiotensin system that contributes to hypertension. Although platelets in blood from hypertensive subjects have an abnormal biological profile, it is unclear if circulating Ang II influences platelet aggregation or thrombus formation. One of the abnormalities presented to the platelets during hypertension is an elevated plasma concentration of serotonin (5-HT) caused by reduced 5-HT uptake secondary to loss of the 5-HT transporter (SERT) on the platelet plasma membrane. In the current study, we evaluated in vivo platelet function after 7 days of subcutaneous Ang II infusion to establish hypertension in mice and additionally assessed the biology of isolated platelets exposed to Ang II in vitro. The administration of Ang II elevated systolic blood pressure, but markers of platelet activation including P-selectin and PEJon/A staining were _disibledevent=font-size:10pt;line-height:1.5;font-family:Verdana;>5-HT in platelets, an event
Results: 22 hypoxemic patients were selected for the study based on their diagnosis of COPD (from history and spirometry) along with age and sex matched controls. Presence of comorbidities and other factors that cause platelet activation were excluded. Level of platelet aggregation was determined by several experiments. By an aggregometer using platelet agonists (thrombin and ADP) it was found that platelet aggregation was significantly higher in hypoxemic COPD patients than normal healthy controls. Fluorescence spectrophotometer was used to measure intracellular calcium as a marker of platelet activation and it was found that hypoxemic COPD patients had significantly higher platelet aggregation than normal healthy controls. However no significant difference was found in other markers of platelet activation studied namely P-selectin exposure and PAC-1 binding between the two groups ...
ABSTRACT. Angiotensin II (Ang II) is a critical component of the renin-angiotensin system that contributes to hypertension. Although platelets in blood from hypertensive subjects have an abnormal biological profile, it is unclear if circulating Ang II influences platelet aggregation or thrombus formation. One of the abnormalities presented to the platelets during hypertension is an elevated plasma concentration of serotonin (5-HT) caused by reduced 5-HT uptake secondary to loss of the 5-HT transporter (SERT) on the platelet plasma membrane. In the current study, we evaluated in vivo platelet function after 7 days of subcutaneous Ang II infusion to establish hypertension in mice and additionally assessed the biology of isolated platelets exposed to Ang II in vitro. The administration of Ang II elevated systolic blood pressure, but markers of platelet activation including P-selectin and PEJon/A staining were not changed. However, the aggregation response to collagen was reduced in isolated ...
Glycoprotein Ib-IX-V (GPIb-IX-V) is a platelet adhesion receptor complex that initiates platelet aggregation. Glycoprotein Iba (GPIba) is the central component of the GPIb-IX-V complex, anchoring the complex to the cytoskeleton and harboring the binding site for von Willebrand factor (vWF). Previous studies suggest that the coagulation function in pigs differs from that in humans, especially with respect to the interaction between vWF and platelets. However, we have little knowledge about the function of porcine platelets, which is important with regard to studies of cardiovascular disease, clotting, and surgery that use pigs as animal models. To extend this information, we cloned and analyzed the porcine GPIba sequence. Porcine GPIba contains 1891 nucleotides and includes an open reading frame that encodes 627 amino acids. The nucleotide sequence showed 67% identity with human GPIba, whereas the deduced amino acid sequences were 59% identical. The vWF binding domain shares the highest identity ...
BioAssay record AID 336312 submitted by ChEMBL: Antiplatelet activity against bovine citreated platelet assessed as inhibition of ADP-induced platelet aggregation up to 278 ug/ml after 6 mins.
To delineate the critical top features of platelets necessary for balance and formation of thrombi, thromboelastography and platelet aggregation measurements were employed in whole blood of normal individuals and of those with Bernard-Soulier Syndrome (BSS) and Glanzmanns Thrombasthenia (GT). generation of stable thrombi, a potentially significant feature in individual medical results. Introduction An initial step in thrombus formation in the hurt vascular endothelium is the adhesion of platelets to shown subendothelial elements, e.g., von Willebrand Aspect (vWF), under high prices of shear, via the connections from the platelet glycoprotein (GP) 1b/V/IX receptor complicated with subendothelial vWF [1]. This tethering of platelets after that promotes their firmer binding to subendothelial collagen (COL) fibres via platelet receptors, e.g., GPVI [2], [3] and integrin II1 [4]. In this procedure, platelets are turned on, resulting in platelet shape adjustments, aggregation, discharge of aggregation ...
TY - JOUR. T1 - Inhibitory signaling of 17β-estradiol in platelet activation. T2 - The pivotal role of cyclic AMP-mediated nitric oxide synthase activation. AU - Wu, Gong-Jhe. AU - Lee, Jie Jen. AU - Chou, Duen-Suey. AU - Jayakumar, Thanasekaran. AU - Hsiao, George. AU - Chen, Wei Fan. AU - Sheu, Joen-Rong. PY - 2010/12/15. Y1 - 2010/12/15. N2 - Arterial thromboses are mostly composed of platelets adherent to ruptured endothelial surfaces. Platelets are anucleated cells; therefore, they represent an excellent and unique model to selectively investigate the signaling pathways mediating the nongenomic effects of estrogen. The aim of this study was to examine the signal transduction pathways of 17β-estradiol in preventing platelet activation. In this study, 17β-estradiol (5~10μM) exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists (i.e., thrombin). 17β-Estradiol-inhibited collagen-stimulated platelet activation accompanied by [Ca2+]i ...
Octadecadienoic acids (linoleic acid and linolelaidic acid) and the diacylglycerol, 1-oleoyl-2-acetyl-rac-glycerol (OAG) concentration-dependently induced activation of gel-filtered human platelets, i.e. aggregation and phosphorylation of 20 kDa and 47 kDa peptides. In contrast, octadecenoic acids (oleic and elaidic acid) and octadecanoic (stearic) acid were inactive. Octadecadienoic acid-induced platelet activation was suppressed by the protein kinase C inhibitor, polymyxin B, but not by the cyclooxygenase inhibitor, indomethacin. OAG-induced activation was potentiated by octadecadienoic acids present at non-stimulatory concentrations. Our data suggest that octadecadienoic acids and diacylglycerol synergistically induce platelet activation via protein kinase C. Furthermore, linolelaidic acid may provide a useful experimental tool to study fatty acid regulation of protein kinase C in intact cells. ...
Staphylococcus aureus is an opportunistic pathogenic bacterium known for its ability to interact with platelets and modulate their function. S. aureus lipoproteins are one of the major groups of bacterial surface molecules and are released into the extracellular milieu where they are recognized by host immune cells. The aim of this study was to determine the role of S. aureus lipoproteins in S. aureus-platelet interactions. Platelet aggregation and binding assays using S. aureus wild type and lgt strains showed that, S. aureus lipoproteins contribute towards binding of the pathogen to platelets. Lipoproteins present in extracellular milieu also bind platelets. Platelet spreading, thrombus formation, agonist induced platelet aggregation and αIIbβ3 activation were inhibited by cell-free lipoproteins. CD36 was identified as the major platelet surface molecule interacting with S. aureus lipoproteins. Antibody neutralization demonstrated that functional inhibition of platelet activation caused by ...
Seventy-five consecutive patients with normal platelet counts were investigated for easy bruising. All had a normal coagulation profile, and all except four were women. None were on aspirin or other antiplatelet agents. Two specific groups could be delineated. In type I (44 patients, mean age, 35), platelet function was normal to supranormal. Megathrombocyte number was elevated in 60% of patients and correlated with the presence of antiplatelet antibody in 30% of patients. In type II (31 patients, mean age, 34), platelet function was abnormal: impaired epinephrine aggregation (primary and secondary wave) in 97%, impaired connective tissue aggregation in 77%, and impaired ADP aggregation in 42%. Megathrombocyte number was elevated in 71%, and antiplatelet antibody was present in 38% of patients. The easy bruising syndrome can be differentiated into two categories: type I, in which a platelet abnormality is unlikely, and type II, in which a platelet abnormality exists. Elevated incidence of ...
The work herein examines in vitro platelet aggregation in response to fluid shearing motion. Our specific aim is to characterize shear-induced aggregation by means of kinetic measurements. In doing so we consider plausible physicochemical mechanisms for platelet activation in the shear field. Besides resolving some questions concerning the activation of platelets by shear forces, this study further implicates fluid mechanical factors in thrombosis and arterial disease. Specific results may also apply to the design and evaluation of blood-contacting artificial devices. The experimental procedure centers on the use of a rotational viscometer to apply a controlled shearing motion to platelet suspensions for prescribed times. We quantify aggregation through changes in particle size histograms and associated measures (e.g. total number of particles). Additional insight into the aggregation response comes from interpreting kinetic data using the coalescence equation, a population balance specific for ...
It has been proposed that adsorbed glycoproteins such as fibrinogen and gamma-globulin induce platelet adhesion at blood-polymer interfaces. The importance of oligosaccharide groups in the glycoproteins proved to be responsible for platelet adhesion and aggregation via possible complex formation. Several studies have provided evidence that the proposed mechanism was involved in platelet adhesion on polymer surfaces. To minimize or prevent platelet adhesion on polymers, prostaglandins (PGs), potent inhibitors of platelet aggregation and PG-heparin (HEP) conjugate, were combined with polymers via physical dispersion or chemical immobilization on the surfaces. Albumin-HEP conjugate-adsorbed surfaces also showed significant reduction of platelet adhesion.
Human platelet-rich plasma (PRP) was irradiated in vitro with a fiberoptic Nd:YAG laser-heated metal cap to study its effects on platelets. The energy of the laser was 5 and 10 watts with an irradiation time of 0, 3, 6, and 9 seconds and 14 watts with an irradiation time of 0, 3, 4, and 5 seconds, respectively. The irradiated PRPs were analyzed for platelet count, aggregation reaction, thromboxane (TX)B2 measurement and electron microscopy. Various degrees of decrease in platelet count were observed in all groups. Except the 5Wx3S group, the other groups showed an increase in the maximum aggregation rate of platelets, which corresponded to the enhancement of TXB2 formation. It was also demonstrated by a transmission electron microscopy in 10Wx3S, 10Wx6S, 10Wx9S, 14Wx3S, 14Wx4S, and 14Wx5S energy groups that alpha- and dense-particles in irradiated platelets became sparse in number or even disappeared, less electron density, irregularity in size and shape, and a tendency for these particles to ...
This study was conducted to examine the mechanism(s) of synergistic interaction of adrenaline and platelet-activating factor (PAF) mediated human platelet aggregation. We found that platelet aggregation mediated by subthreshold concentrations of PAF (5-8 nM) plus adrenaline (0.5-2 μM) was inhibited by both α2-adrenoceptor blocker (yohimbine) and PAF receptor antagonist (WEB2086). While examining the role of the downstream signalling pathways, we found that this synergism was inhibited by calcium channel blockers, verapamil, and diltiazem. In addition, platelet aggregation by co-addition of adrenaline and PAF was also inhibited by very low concentrations of phospholipase C (PLC) inhibitor (U73122; IC50 = 0.2 μM), the MAP kinase inhibitor, PD98059 (IC50 = 3 μM) and cyclooxygenase (COX-1) inhibitors including indomethacin (IC50 = 0.25 μM), flurbiprofen (IC50 = 0.7 μM) and piroxicam (IC50 = 7 μM). However, the COX-2 inhibitor, nimesulide, was also effective in inhibiting the aggregation. The
The latter work was performed with murine species and, of note, many differences have been emphasized in megakaryocyte localization and ultrastructure of proplatelet formation, between mice and humans.32 The present study performed on human MKs sheds additional light on how these large protrusions can be induced to fragment into small platelets by shear forces in flowing blood. This is also in keeping with evidence that the pulmonary circulation could be an important site of platelet production, as the lung capillaries would be the first to be encountered by cells leaving the bone marrow.28 Indeed, the large cytoplasmic fragments and the isolated platelet-sized fragments that we observed in real time to form on the coverslip during the flow assay resembled those seen downstream of the pulmonary circulation in vivo.33 In our conditions, high shear rates were essential to proplatelet and platelet formation during an exposure time of 20 minutes. In contrast, no proplatelet or platelet was generated ...
REPORT DESCRIPTIONPlatelet rich plasma (PRP) is a blood plasma product in which concentration of platelets is elevated four to eight times higher than the normal blood platelet concentration. PRP is also called platelet rich gel, platelet enriched plasma and platelet enriched gels; and is used in effective treatment...
To prepare PRP, a small amount of blood is taken from the patients arm. The blood is then placed in a centrifuge. The centrifuge spins & separates the platelets form the rest of the blood components. The entire process takes less than 15 minutes and increases the concentration of platelets & growth factors up to 600%. Using the patients own blood, specially prepared platelets are taken and re-injected into the affected area. These platelets release special growth factors that lead to tissue healing. By using the concentrated platelets, we increase the growth factors up to eight times which promotes temporary relief and stops inflammation. PRP injections actually heal the area over a period of time. This can be anywhere from one to three months.. The human body has a remarkable ability to heal itself, and by re-injecting concentrated platelets, we are facilitating the natural healing process. The PRP injections are calling in stem cells to repair the area. When performing these injections, we ...
Title: Platelet and Soluble Glycoprotein VI - Novel Applications in Diagnosis and Therapy. VOLUME: 12 ISSUE: 12. Author(s):Boris Bigalke, Margitta Elvers, Tanja Schonberger and Meinrad Gawaz. Affiliation:Medizinische Klinik III, Eberhard-Karls-Universitat Tubingen, Otfried-Muller-Str.10, D-72076 Tubingen, Germany.. Keywords:Platelets, platelet and soluble glycoprotein vi, biomarker, plaque imaging, antithrombotic therapy, molecular imaging, diagnosis, structure, regulation, knockout mice. Abstract: One of the key receptors involved in the prothrombotic stage of an acute coronary syndrome (ACS) is platelet glycoprotein VI (GPVI). This constitutively expressed collagen receptor is platelet-specific and has shown to be a useful biomarker tool for the early detection of atheroslerotic diseases such as ACS and ischemic stroke. In a multimarker panel of several biomarkers, platelet GPVI may contribute to risk stratification and prediction of clinical outcome in patients with symptomatic ...
This thesis describes the Chandler loop, which makes it possible to conduct studies in vitro of molecular and cellular interactions between whole blood and stents. It was possible to monitor activation and inhibition of the cascades systems, leukocytes and platelets by combining different platelet inhibitors and heparin coating of stents. The clinical study was performed on patients with ACS undergoing PCI and stent implantation. In this study platelet activation markers P-selectin, and αIIb/β3 as well as inflammatory markers were followed from baseline during the first 48 hours post-PCI. The same parameters were evaluated in healthy controls for comparison at baseline. In vitro: The activation of blood in the Chandler loops were more pronounced for unmodified stent grafts than for partially heparin coated stent grafts. Heparin coated stent grafts dreated the same activation as the loops alone. This indicated that the Chandler loop system was a feasible tool for evaluation of blood compability ...
The Agg+ strain of S. sanguis induces platelet aggregation or clotting in vivo as predicted by the in vitro data. Aggregation in vitro is all-or-none with a dose-dependent delay (23). In vitro, rabbit platelets aggregate in response to the Agg+ strain in about two minutes. The experiments in vivo had been designed to record hemodynamic and cardiopulmonary responses upon a 1-min infusion of S. sanguis. Direct evidence for platelet aggregation or clotting in vivo include thrombocytopenia and, when compared to the Agg− strain, accumulation of 111Indium-labeled platelets in the lungs (Fig. 5), but not in the spleen. Platelets normally clear from the circulation to the spleen, but the 111Indium-labeled platelets used as tracers do not. The frequency and extent of manifestations of platelet clotting in vivo increase directly with the dose of inoculated Agg+S. sanguis.. Changes in heart rate and blood pressure occur more rapidly than would be predicted by the two minute lag time for in vitro platelet ...
Platelets are small cells that circulate in the blood. They are involved in the formation of blood clots and the repair of damaged blood vessels.. When a blood vessel is injured, platelets stick to the damaged area and spread along the surface to stop the bleeding. This process is called adhesion. At the same time, chemical signals are released from small sacks inside the platelets called granules. This process is called secretion. These chemicals attract other platelets to the site of injury and make them clump together to form what is called a platelet plug. This process is called aggregation. Sometimes the platelet plug is enough to stop a bleed. If the wound is large, however, other proteins called clotting factors are recruited to the site of injury. These clotting factors work together on the surface of the platelets to form and strengthen the blood clot.. ...
A decrease in blood platelets (thrombocytopenia) also may occur. Since platelets are important for the clotting of blood, ... One possible side effect is agranulocytosis, a decrease of white blood cells in the blood. Symptoms and signs of ... Other severe side effects include liver problems and low blood cell counts. Use during pregnancy may harm the baby. ...
Pancytopenia, aplastic anemia, reversible agranulocytosis, low blood platelets, neutropenia. Chloroquine has not been shown to ... and heart problems such as ventricular fibrillation and low blood pressure. Low blood potassium may also occur. While the usual ... Inside red blood cells, the malarial parasite, which is then in its asexual lifecycle stage, must degrade hemoglobin to acquire ... Intravenous potassium chloride may be required, however this may result in high blood potassium later in the course of the ...
Coxon CH, Geer MJ, Senis YA (June 2017). "ITIM receptors: more than just inhibitors of platelet activation". Blood. 129 (26): ... doi:10.1182/blood-2016-12-720185. PMID 28465343. Verbrugge A, Meyaard L (June 2005). "Signaling by ITIM-bearing receptors". ...
CO inhibits blood platelet aggregation and adhesion. CO may play a role as potential therapeutic agent. In mammals, carbon ... It lowers blood pressure and slows hypertensive remodeling of blood vessels, especially thickening of their intima. It also ... Bicarbonate ions are crucial for regulating blood pH. A person's breathing rate influences the level of CO2 in their blood. ... Carbon dioxide is one of the mediators of local autoregulation of blood supply. If its levels are high, the capillaries expand ...
... specifically the platelets in the blood. Platelets are cell fragments in the blood that aid in clotting. Platelets are produced ... Normal platelet counts range from 150,000 to 450,000 platelets per µL of blood. Individuals with XLT usually have drastically ... reduced platelet counts, typically less than 70,000 platelets per µL of blood. Not only are there fewer platelets circulating, ... but individuals with XLT also have smaller platelets. Fewer and smaller platelets causes the efficacy of the clotting mechanism ...
Can have antibodies to blood cells (DAT, anti-neutrophil, anti-platelet). Also, can have positive ANA, RF, ANCA Defective in ... Blood. 116 (14): e35-40. doi:10.1182/blood-2010-04-280347. PMC 2953894. PMID 20538792. Kuehn, H. S.; Caminha, I.; Niemela, J. E ... Blood. 115 (11): 2142-5. doi:10.1182/blood-2009-08-239525. PMID 20068224.[unreliable medical source?] Sneller, Michael C.; Dale ... Blood. 105 (6): 2443-8. doi:10.1182/blood-2004-09-3542. PMID 15542578.[unreliable medical source?] Magerus-Chatinet A, ...
Monitoring of liver enzymes, platelets, and blood cell counts are recommended. Lamotrigine generally has minimal side effects, ... As a result, kidney function and blood levels of lithium are monitored in patients being treated with lithium. Therapeutic ... blood pressure, and waist circumference. Taking antipsychotics for long periods or at high doses can also cause tardive ... as well as some rare but serious side effects such as blood dyscrasias, pancreatitis, exfoliative dermatitis, and hepatic ...
Platelets: inhibit their aggregation and possibly thereby their contribution to blood clotting. Macrophages: inhibit their ... In the model system used to identify them, human platelets pretreated with aspirin to form acetylated COX2 or the statin, ... Eosinophils: inhibit their migration from the blood circulation into inflamed tissues. Monocytes: inhibit their migration ... platelet-activating factor, and PUFA metabolites including in particular leukotrienes (e.g. LTB4), hydroxyeicosatetraenoic ...
Another application in laboratories is blood separation. Blood separates into cells and proteins (RBC, WBC, platelets, etc.) ... The blood waste is then removed and another buffer is added and spun inside the centrifuge again. Once the blood waste is ... Haematocrit centrifuges are used to measure the volume percentage of red blood cells in whole blood. Gas centrifuges, including ...
... the latter may modify platelet aggregation and blood viscosity. Stroke, particularly intracerebral hemorrhage, is the most ...
In particular, platelets involved in wound repair and blood homeostasis release ROS to recruit additional platelets to sites of ... August 2002). "NAD(P)H oxidase-dependent platelet superoxide anion release increases platelet recruitment". Blood. 100 (3): 917 ... "Hydrogen peroxide is involved in collagen-induced platelet activation". Blood. 91 (2): 484-90. doi:10.1182/blood.V91.2.484. ... doi:10.1182/blood.V100.3.917. PMID 12130503. Pignatelli P, Pulcinelli FM, Lenti L, Gazzaniga PP, Violi F (January 1998). " ...
... evidence for aspirin-suppressible platelet activation in vivo". Blood. 80 (8): 1965-71. doi:10.1182/blood.V80.8.1965.1965. PMID ... It may also result in the overproduction of white blood cells and platelets. Most of the health concerns associated with ... Capillaries can become plugged by the very viscous blood, and the flow of blood through the vessels tends to be extremely ... The entire vascular system can become markedly engorged with blood, and circulation times for blood throughout the body can ...
Platelets have been separated from whole blood with a DEP-activated cell sorter. Dielectrophoresis can be used to manipulate, ... Strains of bacteria and viruses red and white blood and cells.[citation needed] DEP can also be used to detect apoptosis soon ... This expression has been useful for approximating the dielectrophoretic behavior of particles such as red blood cells (as ... DEP has made it possible to characterize and manipulate biological particles like blood cells, stem cells, neurons, pancreatic ...
June 2005). "Quantitative validation of different protein precipitation methods in proteome analysis of blood platelets". ... in the biotechnology industry protein precipitation is used to eliminate contaminants commonly contained in blood. The ...
Sources of microvesicles include megakaryocytes, blood platelets, monocytes, neutrophils, tumor cells and placenta. Platelets ... unique delivery of CD154 signal by platelet-derived membrane vesicles". Blood. 111 (10): 5028-36. doi:10.1182/blood-2007-06- ... The release of microvesicles has been shown from endothelial cells, vascular smooth muscle cells, platelets, white blood cells ... Activation of platelets via collagen receptor GPVI stimulates the release of microvesicles from platelet cytoplasmic membranes ...
... blood products; Class VIIIb - Blood & blood components (whole blood, platelets, plasma, packed red cells, etc.). Class IX - ... Class VIIIa - Medical consumable supplies not including blood & ...
Individuals with the syndrome have platelet dysfunction. Since platelets are necessary for blood clotting, individuals will ... Blood. 14 (2): 162-9. doi:10.1182/blood.V14.2.162.162. ISSN 0006-4971. PMID 13618373.[permanent dead link] Khalid Al Aboud; ... bleeding problems due to a platelet abnormality (platelet storage pool defect), and storage of an abnormal fat-protein compound ... If platelet aggregation improves with desmopressin, it may be administered in the preoperative period. However, sometimes ...
In addition to whole blood, the drones deliver platelets, fresh frozen plasma, and cryoprecipitate. As of May 2019, more than ... In addition to whole blood, the drones deliver platelets, frozen plasma and cryoprecipitate. During the COVID-19 pandemic in ... In Ghana, the company began using drones in April 2019 to deliver vaccines, blood, and drugs. He was also the CEO and a co- ... Zipline began drone deliveries in Rwanda in late 2016, and primarily delivers blood to urgent medical situations. ...
A small amount of platelets in blood smears compared to the normal range of 150,000 to 450,000 platelets in microliter of blood ... Platelets assist in blood clotting and coagulate when there are damages blood vessels. This coagulation attempts to cease ... Thrombocytopaenia means there is low platelet volume in the blood. This means there are less platelets to coagulate in presence ... platelets can reach the size of an erythrocytes. This large platelet size can be compared with MYH9 disorders where platelet ...
Folinic acid protects against the decrease in platelets and white blood cells induced by pyrimethamine. Prednisone may be used ... Seropositivity (positive blood test result) for Toxoplasma is very common and therefore not useful in diagnosis; however, a ... During treatment with pyrimethamine, leukocyte and platelet counts should be monitored weekly. ...
His hematology research included important work on blood coagulation, blood platelets, hemorrhagic diseases, and hemoglobins. ...
Collagen as haemostat: When collagen interacts with platelets it causes a rapid coagulation of blood. This rapid coagulation ... Collagen bases haemostat reduces blood loss in tissues and helps manage bleeding in cellular organs like the liver and spleen. ... In recent studies, silk fibroin has been found to possess antiagulation properties and platelet adhesion. Silk fibroin has been ...
Severe side effects may include low blood platelets, low white blood cells, and blood clots. Use during pregnancy may harm the ... Blood. 119 (12): 2764-7. doi:10.1182/blood-2011-08-373514. PMID 22323483. "FDA approves lenalidomide oral capsules (Revlimid) ... "Revlimid faces NICE rejection for use in rare blood cancer Watchdog's draft guidance does not recommend Celgene's drug for NHS ... November 2011). "Cereblon expression is required for the antimyeloma activity of lenalidomide and pomalidomide". Blood. 118 (18 ...
These marrow components can be divided into plasma, red blood cells, platelets, and nucleated cells. The adult stem cell ... Most of these cells are CD34+ heme progenitors (destined to differentiate into blood components), while very few are actually ... Most of the adult bone marrow consists of blood cells in various stages of differentiation. ... platelet lysate and dexamethasone". Am J Case Rep. 9: CR246-51. Centeno CJ, Schultz JR, Cheever M, Robinson B, Freeman M, ...
ADP is stored in dense bodies inside blood platelets and is released upon platelet activation. ADP interacts with a family of ... ADP in the blood is converted to adenosine by the action of ecto-ADPases, inhibiting further platelet activation via adenosine ... Under normal conditions, small disk-shape platelets circulate in the blood freely and without interaction with one another. ... ADP receptors found on platelets (P2Y1, P2Y12, and P2X1), which leads to platelet activation. P2Y1 receptors initiate platelet ...
Healthy myeloid cells produce red blood cells, platelets and white blood cells (apart from lymphocytes). For CML to develop, an ...
April 2007). "Platelet TLR4 activates neutrophil extracellular traps to ensnare bacteria in septic blood". Nature Medicine. 13 ... Hematopoiesis Blood count Haematopoiesis Immune system Innate immune system Trogocytosis White blood cell WebMD (2009). " ... Neutrophils do not return to the blood; they turn into pus cells and die. Mature neutrophils are smaller than monocytes, and ... Once neutrophils have received the appropriate signals, it takes them about thirty minutes to leave the blood and reach the ...
"Platelet TLR4 activates neutrophil extracellular traps to ensnare bacteria in septic blood". Nature Medicine. 13 (4): 463-9. ... Whereas basophilic white blood cells stain dark blue and eosinophilic white blood cells stain bright red, neutrophils stain a ... of all white blood cells (leukocytes). The stated normal range for human blood counts varies between laboratories, but a ... Blood. 116 (4): 625-7. doi:10.1182/blood-2010-01-259028. PMID 20410504. Wheater PR, Stevens A (2002). Wheater's basic ...
Bearer, E. L.; Abraham, M. T. (1999). "2E4 (kaptin): a novel actin-associated protein from human blood platelets found in ... Blood. 99 (12): 4466-4474. doi:10.1182/blood.v99.12.4466. ISSN 0006-4971. PMC 3376088. PMID 12036877. Bearer, E. L.; Chen, A. F ... Li, Zhi; Kim, Eric S.; Bearer, Elaine L. (2002). "Arp2/3 complex is required for actin polymerization during platelet shape ... proteins that regulate actin dynamics in platelets, (Bearer and Abraham, 1999; Bearer et al. Ann. of Hum. Genet, 2000). Recent ...
Common adverse effects include low white blood cells, low blood platelets, anemia, swelling, rash, and diarrhea. Severe adverse ... announced that dasatinib may increase the risk of a rare but serious condition in which there is abnormally high blood pressure ...
New studies in mice suggest that blood platelets can destroy deadly malaria parasites, but a single dose of aspirin may be ... Platelets are well known for their role in blood clotting and blood vessel repair. Previous studies have shown that platelets ... We believe that s because platelets bind to infected red blood cells and are taken out of circulation because of that, Foote ... New studies in mice suggest that blood platelets can destroy deadly malaria parasites, but a single dose of aspirin may be ...
... caused by low blood platelets. Have any of you ever ... ... Low Blood Platelets By kschmitz, January 25, 2005. in Related ... caused by low blood platelets. Have any of you ever had this diagnosis? Low platelets can be the result of an autoimmune ... Just wondering how the platelets and petechaia turned out -- still there? How low are your platelets? ... Blood? Same. Since that period I have ordered re-tests on all three types of tests, this time from different companies, and ...
... a change in diet can help build up blood platelets. An organic diet rich in nutrients can have a beneficial effect on someones ... What Is the Normal Blood Platelet Level?. A: In healthy adults, the normal blood platelet count is 150,000 to 400,000 platelets ... What Are High Blood Platelets a Sign Of?. A: Having too many platelets in the blood is a sign of either thrombocytosis or ... What Is the Easiest Way to Raise Blood Platelets?. A: The easiest way of increasing the level of blood platelets is by eating ...
Research in the Laboratory for Hemostasis and Platelet Biology, led by Dr. Andrew Johnson, focuses on understanding genetic and ...
2. Comparative counts of platelets in arteries and veins show that arterial blood contains a larger number of platelets than ... It is concluded that new platelets are added to the blood in the capillary areas of the lungs, and that there is a ... THE PRODUCTION OF BLOOD PLATELETS IN THE LUNGS. W. H. Howell, D. D. Donahue ... venous blood. This difference is accentuated under experimental conditions that cause a reduction in the number of platelets. ...
SEM image of Human blood platelets in the process of clotting. This sample was taken from the root of a tooth from an 18 year ... SEM image of Human blood platelets in the process of clotting. This sample was taken from the root of a tooth from an 18 year ...
Join friendly people sharing true stories in the I A Positive Blood Platelets Required Urgently group. Find forums, advice and ... Do You A Positive Blood Platelets Required Urgently? ... More People Who Positive Blood Platelets Required Urgentlies. * ... has to go thro bone marrow transplantation and he needs A+ blood platelets on urgent basis. Please contact the us on the ...
When normal blood is analyzed, platelet deposition is a shear and a time dependent process, reaching maximal levels within 2 ... A new method and device in which whole blood platelet deposition and aggregation on extracellular matrix (ECM) under defined ... A new method for quantitative analysis of whole blood platelet interaction with extracellular matrix under flow conditions.. ... Blood samples of vWD patients showed a very low adhesion and aggregation at high shear rate as reflected by very low surface ...
List of causes of Cough and Low blood platelet level and Mouth symptoms, alternative diagnoses, rare causes, misdiagnoses, ... Low blood platelet level:*52 causes: Low blood platelet level *Introduction: Low blood platelet level *Low blood platelet level ... Cough AND Low blood platelet level AND Mouth symptoms - Causes of All Symptoms *Cough OR Low blood platelet level OR Mouth ... Cough and Low blood platelet level and Mouth symptoms and Abnormal blood test symptoms (12 causes) ...
Clinicians need to be aware of bacterial contamination of blood products, especially platelets. ... In practice, the type of platelet donation (apheresis or whole blood-derived platelets) has dictated the bacterial detection ... Clinician is contacted by the blood collection or transfusion service with information involving a blood or blood component ... Most blood collection centers culture apheresis platelets (derived from single donors), and release the unit after the culture ...
Hospitals and blood banks are adopting new measures to improve the safety of donated platelets-the tiny cells that make blood ... Hospitals and blood banks are adopting new measures to improve the safety of donated platelets-the tiny cells that make blood ... Unlike other blood components such as red cells, which are refrigerated, platelets must be stored at room temperature to remain ... A growing number of studies show that standard tests performed by blood banks before they ship platelets to hospitals miss the ...
Ive had low blood platelets for as long as I can remember.Even before I discovered I was Hep C+. I went thru tx( peg-intron- ... The hepatitis C virus (HCV) is spread by blood-to-blood contact with an infected persons blood. Many people with HCV infection ... or back up of blood flow. THE LARGE SPLEEN sequesters or HIDES platelets....hence the low platelets (thrombocytopenia) 3) The ... Ive had low blood platelets for as long as I can remember.Even before I discovered I was Hep C+. I went thru tx( peg-intron- ...
Blood platelets are deceptively simple cells. They circulate in the form of flattened disks, dwarfed by the larger erythrocytes ... The Cytoskeleton of Human Blood Platelets. In: Harris J.R. (eds) Megakaryocytes, Platelets, Macrophages, and Eosinophils. Blood ... White, J. G., and Sauk, J. J., 1984, Microtubule coils in spread blood platelets, Blood 64: 470-478.PubMedGoogle Scholar ... Actin Filament Human Platelet Detergent Extraction Parallel Bundle Human Blood Platelet These keywords were added by machine ...
Changes in blood platelets triggered by COVID-19 could contribute to the onset of heart attacks, strokes, and other serious ... Tags: Aspirin, Blood, Blood Clot, Blood Pressure, Diabetes, Gene, Gene Expression, Genetic, Heart, Hematology, High Blood ... Manne, B.K., et al. (2020) Platelet Gene Expression and Function in COVID-19 Patients. Blood. doi.org/10.1182/blood.2020007214. ... Changes in blood platelets triggered by COVID-19 could contribute to the onset of heart attacks, strokes, and other serious ...
... platelet aggregating factor) in human and animal blood plasma areeffected using a reagent of blood platelets and snake venom ... The reagent andtests may also suitably employ dried blood platelets. The reagentmay comprise dried platelets and either ... in human and animal blood plasma areeffected using a reagent of blood platelets and snake venom havinga positive platelet ... The reagent andtests may also suitably employ dried blood platelets. The reagentmay comprise dried platelets and either ...
Blood group alters platelet binding kinetics to von Willebrand factor and consequently platelet function Eimear Dunne, Qin M. ... Blood 2019 :blood-2018-10-881557; doi: https://doi.org/10.1182/blood-2018-10-881557 ... Blood 2019 :blood-2018-11-835371; doi: https://doi.org/10.1182/blood-2018-11-835371 ... Megakaryocytes and platelets from a novel human adipose tissue-derived mesenchymal stem cell line Keiichi Tozawa, Yukako Ono- ...
What causes the increase? What is the danger of too many platelets? -- P.D. ... and my platelet count was 470,000. Three months ago it was 500,000. A week ago it was 650,000. ... Donohue: I had blood work done six months ago, ... TOO MANY PLATELETS CAN LEAD TO BLOOD PROBLEMS. DR. PAUL DONOHUE ... Polycythemia is the blood illness where bone marrow makes too many red and white blood cells and too many platelets. By now, ...
The American Red Cross urges eligible donors to end summer on a positive and potentially lifesaving note with a blood or ... but blood and platelet donors are still needed to help ensure blood products are available to meet hospital patient needs. ... Blood can be safely donated every 56 days and platelets can be given every seven days - up to 24 times a year. To make an ... Red Cross urges eligible donors to close out summer with a blood or platelet donation ...
Platelets are a part of the blood that helps the blood clot. ... shows if you have antibodies against platelets in your blood. ... This blood test shows if you have antibodies against platelets in your blood. Platelets are a part of the blood that helps the ... Abnormal results show that you have anti-platelet antibodies. Anti-platelet antibodies may appear in the blood due to any of ... Platelet antibody - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: ...
Emerging roles for platelets as immune and inflammatory cells. Blood. 2014;123(18):2759-2767. ... In this issue of Blood, Stefanini et al untangle the specific roles of RAP1A and RAP1B in platelet production, signal ... Genome-wide RNA-seq analysis of human and mouse platelet transcriptomes. Blood. 2011;118(14):e101-e111. ... RAPid signaling in platelets. Blood, 132(18), 1864-1865. Accessed November 14, 2018. https://doi.org/10.1182/blood-2018-09- ...
City of Hope strongly supports and values the uniqueness of all individuals and promotes a work environment where diversity is embraced. ...
BE A HERO THIS VALENTINES DAY Schedule an appointment to donate blood or platelets using the Red Cross Blood Donor App, ... POWER REDS AND PLATELETS NEEDED Eligible donors with types O, A negative and B negative blood are urged to make a Power Red ... Blood and platelet donors are heroes who answer the call to roll up a sleeve and help ensure an adequate supply is available ... Unlike whole blood, which can be safely donated every 56 days, platelets can be donated every seven days, up to 24 times a year ...
Transfusion of whole blood, which contains plasma and all blood cell types including red blood cells and platelets, or packed ... Thrombocytopenia refers to an abnormally low blood-concentration of platelets, which are blood cells that promote blood ... Dogs with blood platelet concentrations of less than 40,000 per microliter of blood are at risk for spontaneous bleeding. ... Low Blood Platelets) in Dogs. Treatment for thrombocytopenia depends on the underlying cause of the low platelet count. ...
Platelets allow blood to clot, so the main symptoms of low blood platelets include bruising, an inability to stop bleeding from ... Low blood platelets can be a dangerous condition. ... Platelets are cells in the blood that help the blood to clot, ... Low blood platelets can be a dangerous condition. Platelets allow blood to clot, so the main symptoms of low blood platelets ... There are several treatments available for people with low blood platelets. If your low blood platelet count is due to ITP, you ...
... the BMC wants blood banks to supply blood and its components such as platelets, plasma, judiciously. ... To avoid adverse effects in patients as a result of excessive and unnecessary blood transfusions, ... The civic body wants blood banks to monitor supply of blood platelets and other components and identify any over-prescription ... the BMC wants blood banks to supply blood and its components such as platelets, plasma, judiciously. mumbai Updated: May 22, ...
... and platelets. [M -C Shen; C -M Teng; Akikazu Takada;] ... "Blood Platelets"@en ;. schema:name "Blood platelets"@en ;. .. < ... Blood platelets. a schema:Intangible ;. schema:name "Blood platelets"@en ;. .. ... http://experiment.worldcat.org/entity/work/data/369351063#Topic/blood_platelets> # Blood Platelets. a schema:Intangible ;. rdfs ... schema:about blood_platelets> ; # Blood Platelets. schema: ...
In a healthy person, a large number of platelets are manufactured and stored in the body. ... Platelets are the component of blood that helps with clotting. ... Platelets are about a quarter of the size of red blood cells ... Platelets are the component of blood that helps with clotting. If an injury or blood loss occurs, platelets are released, and a ... Regular donors can give platelets every two weeks. Ask us about donating platelets at your next whole blood donation or give us ...
blood platelet synonyms, blood platelet pronunciation, blood platelet translation, English dictionary definition of blood ... n. any of the minute, nonnucleated cellular elements in mammalian blood essential for coagulation. Noun 1. blood platelet - ... blood platelet. Also found in: Thesaurus, Medical, Encyclopedia. blood platelet. n.. See platelet. ... blood platelet - tiny bits of protoplasm found in vertebrate blood; essential for blood clotting. platelet, thrombocyte ...
The blood platelet in transfusion therapy. [Tibor J Greenwalt; G A Jamieson; American National Red Cross.;] ... Blood platelets--Transfusion a schema:Intangible ;. schema:name "Blood platelets--Transfusion"@en ;. . ... Blood platelets--Transfusion a schema:Intangible ;. schema:name "Blood platelets--Transfusion"@en ;. . ... The blood platelet in transfusion therapy. Author:. Tibor J Greenwalt; G A Jamieson; American National Red Cross.. ...
... Platelet plug formation is a major step in physiological hemostasis, but also in ... Approximately 750 billion platelets circulate in human blood, constantly scanning the vasculature for damage of the endothelial ... followed by platelet activation, adhesion and spreading. During this stepwise processes platelets undergo dramatic shape ... Our main goal is to dissect the molecular and mechanical cues regulating platelet cytoskeleton dynamics and platelet motility ...
Platelets from all donor types are needed.Platelets have a very limited shelf life of five days and are delivered quickly to ... Patients undergoing bone marrow transplants, surgeries, chemotherapy, radiation or organ transplants often need platelets to ... Platelets are blood cells that help control bleeding. ... Platelets are blood cells that help control bleeding. Patients ... Platelet donors are eligible every two weeks. The collection process is longer than whole blood so you should be prepared to ...
... or give blood on board the Dana-Farber Cancer Institute/Brigham and Womens Hospital Blood Mobile, you are making a life-saving ... When you donate blood or platelets at the Kraft Family Blood Donor Center at Dana-Farber Cancer Institute and Brigham and ... All of the blood and platelets collected at the Kraft Center and on the Blood Mobile benefit patients at Dana-Farber and ... When you donate blood or platelets at the Kraft Family Blood Donor Center at Dana-Farber Cancer Institute and Brigham and ...
Platelets are really special, because thats what were using for trauma victims, someone who has just got of surgery or cancer ... It turns out the platelet donation process is a bit more time-consuming that the typical blood donation-it can take up to two ... He knows the location well, his donation of a pint of blood platelets brings his total contributions, to date, to nearly 50 ... Donors can specify whether theyre willing to give plasma, red blood cells or platelets. ...
Donating blood or platelets is safe and simple, and it can save lives. ... More than 44,000 blood donations are needed every day, according to the American Red Cross. ... How to donate blood or platelets. If youd like to donate blood or platelets, a good first step is to find your local Red Cross ... Why blood and platelet donations are needed. Unlike medicine, blood products cannot be made in a laboratory. But sometimes, ...
Re: low blood platelet you should for sure ask about itp i also had it when i was younger and low platelet count is the biggest ...
  • Experimental studies show that a reduction in the number of platelets also inhibits thrombosis, but these treatments also interfere with platelet function. (sciencemag.org)
  • Only five percent of females and 20 percent of males with normal platelet counts died. (webwire.com)
  • For example, low platelet counts are often seen in malaria patients in the early stages of infection. (webwire.com)
  • Blood samples of vWD patients showed a very low adhesion and aggregation at high shear rate as reflected by very low surface coverage (5.2%) and average particle size of single platelets (21.3 microns2). (nih.gov)
  • When normal blood is analyzed, platelet deposition is a shear and a time dependent process, reaching maximal levels within 2 min at high shear rate (1300 s-1) of about 20% surface coverage and average aggregate size of about 40-50 microns 2. (nih.gov)
  • Haserück, Nadine (2007): Platelet activation and platelet-monocyte aggregate formation by the atherosclerotic plaque lipid lysophosphatidic acid. (uni-muenchen.de)
  • Such aggregation is the in vitro counterpart of in-vivo platelet clumping seen in AA oxidopathy and shown in figure 11. (aliscience.org)
  • LPA-induced aggregation in blood could be completely blocked by the ADP- scavenging enzyme, apyrase, and antagonists of the platelet ADP-receptors P2Y1 and P2Y12. (uni-muenchen.de)
  • Thus antagonists of platelet P2Y1 and P2Y12 receptors, especially in donors highly sensitive to LPA, might be useful in preventing LPA-elicited thrombus formation in patients with cardiovascular diseases. (uni-muenchen.de)
  • A new method and device in which whole blood platelet deposition and aggregation on extracellular matrix (ECM) under defined shear conditions is quantitatively evaluated was developed. (nih.gov)
  • A 0.25 mL aliquot of citrated whole blood is placed on ECM and a defined shear rate is applied for 2 min using a cone and plate device. (nih.gov)
  • GT samples at a high shear rate demonstrated surface coverage similar to normal blood samples (21.7%) but with average particle size of single platelets (21.3 microns2). (nih.gov)
  • If you do happen to sustain a bodily wound or injury, these platelet cells move towards the site and bind damaged blood vessels and form a blood clot. (adamkempfitness.com)
  • Professor Karlheinz Peter from the Baker Institiute has done some research showing platelets in your blood - which we target to bust strokes/heart attacks - also clot to tumours. (nine.com.au)
  • In a scientific study of mice with a blood platelet disorder, those who consumed 32 percent fewer calories had an improved platelet count and a longer lifespan. (reference.com)
  • Because normal hemostasis requires that the platelet concentration remain within a physiological range in the circulation, we evaluated whether lowering the number of circulating platelets-but only to a value still within the normal range-by inhibiting platelet formation in the bone marrow inhibits acute thrombogenesis in baboons. (sciencemag.org)
  • New studies in mice suggest that blood platelets can destroy deadly malaria parasites, but a single dose of aspirin may be enough to thwart their killing power. (webwire.com)
  • This study, published in the February 6, 2009 issue of the journal Science, is the first to demonstrate that platelets can kill parasites in the Petri dish and in mice. (webwire.com)
  • During those studies, they discovered that platelet-deficient mice were much more likely to die of malaria than mice with normal platelets. (webwire.com)
  • When these platelet-deficient mice were infected with Plasmodium chabaudi, a rodent version of the malaria parasite, half of the females and all of the males died of malaria. (webwire.com)
  • To ensure that their original observation was not due to other genetic changes caused by knocking out the Mpl gene, the researchers eliminated platelets by giving the mice aspirin, which inactivates platelets. (webwire.com)
  • Platelets are well known for their role in blood clotting and blood vessel repair. (webwire.com)
  • Thrombocytes are small blood components that are produced in the bone marrow, and they play a key role in blood clotting. (adamkempfitness.com)
  • These two parameters demonstrated positive correlation with the platelet count and the hematocrit. (nih.gov)
  • LPA directly induced platelet shape change in blood and platelet-rich plasma (PRP) obtained from all blood donors. (uni-muenchen.de)
  • Albumin was one of the main inhibiting factors of platelet shape change in plasma. (uni-muenchen.de)
  • Interestingly LPA, at concentrations slightly above plasma levels, induced platelet shape change and aggregation in blood. (uni-muenchen.de)
  • LPA at low concentrations, starting slightly above plasma level, was also capable of eliciting platelet-monocyte conjugate formation. (uni-muenchen.de)
  • Previous studies have shown that platelets are active in the body s innate immune system, which responds rapidly to invading pathogens. (webwire.com)
  • We reduced the platelet count with an inhibitor against the megakaryocyte-promoting hormone thrombopoietin and then showed that experimental occlusive thrombogenesis on collagen-coated vascular grafts was reduced, without impairment of primary hemostasis. (sciencemag.org)
  • The new method is an alternative method to clinically evaluate platelet function under close to physiological conditions. (nih.gov)
  • The main function of these blood components is to stop the bleeding of damaged blood vessels. (adamkempfitness.com)
  • These results suggest that suppressing platelet production without interfering with the hemostatic function of platelets may offer a safe alternative to current therapies for prevention of stroke and heart attack triggered by blood clotting. (sciencemag.org)
  • Research in the Laboratory for Hemostasis and Platelet Biology, led by Dr. Andrew Johnson, focuses on understanding genetic and genomic underpinnings of this individual variability in therapeutically targeted CVD pathways. (nih.gov)
  • however, they also impair platelet-dependent hemostasis that staunches bleeding from wounds and can therefore produce excessive bleeding. (sciencemag.org)
  • The innate immune response is particularly important in fighting malaria, which causes symptoms once the parasite has invaded the victim s red blood cells. (webwire.com)
  • So they conducted similar experiments in a Petri dish in which they added human platelets to red blood cells infected with Plasmodium falciparum, the most deadly human malaria parasite. (webwire.com)
  • We believe that s because platelets bind to infected red blood cells and are taken out of circulation because of that, Foote said. (webwire.com)
  • Essentially, platelets are cells in the blood stream that help protect the body against an excessive loss of blood when you sustain an injury. (adamkempfitness.com)
  • These platelet cells look like plates when they are in their "non-active" state . (adamkempfitness.com)