Phosphatidylserines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a serine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and serine and 2 moles of fatty acids.Annexin A5: A protein of the annexin family isolated from human PLACENTA and other tissues. It inhibits cytosolic PHOSPHOLIPASE A2, and displays anticoagulant activity.CDPdiacylglycerol-Serine O-Phosphatidyltransferase: An enzyme that catalyzes the formation of phosphatidylserine and CMP from CDPdiglyceride plus serine. EC One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.Phagocytosis: The engulfing and degradation of microorganisms; other cells that are dead, dying, or pathogenic; and foreign particles by phagocytic cells (PHAGOCYTES).Phospholipids: 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.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Phosphatidylethanolamines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.Hydrocortisone: The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions.Membrane Lipids: Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.Fatigue Syndrome, Chronic: A syndrome characterized by persistent or recurrent fatigue, diffuse musculoskeletal pain, sleep disturbances, and subjective cognitive impairment of 6 months duration or longer. Symptoms are not caused by ongoing exertion; are not relieved by rest; and result in a substantial reduction of previous levels of occupational, educational, social, or personal activities. Minor alterations of immune, neuroendocrine, and autonomic function may be associated with this syndrome. There is also considerable overlap between this condition and FIBROMYALGIA. (From Semin Neurol 1998;18(2):237-42; Ann Intern Med 1994 Dec 15;121(12): 953-9)Appetite: Natural recurring desire for food. Alterations may be induced by APPETITE DEPRESSANTS or APPETITE STIMULANTS.Sleep: A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility.Fatigue: The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Parasympathetic Nervous System: The craniosacral division of the autonomic nervous system. The cell bodies of the parasympathetic preganglionic fibers are in brain stem nuclei and in the sacral spinal cord. They synapse in cranial autonomic ganglia or in terminal ganglia near target organs. The parasympathetic nervous system generally acts to conserve resources and restore homeostasis, often with effects reciprocal to the sympathetic nervous system.Circadian Rhythm: The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs and stimuli, hormone secretion, sleeping, and feeding.Exercise: Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.Saliva: The clear, viscous fluid secreted by the SALIVARY GLANDS and mucous glands of the mouth. It contains MUCINS, water, organic salts, and ptylin.Sleep, REM: A stage of sleep characterized by rapid movements of the eye and low voltage fast pattern EEG. It is usually associated with dreaming.Longevity: The normal length of time of an organism's life.Thiamin Pyrophosphokinase: An enzyme that catalyzes the formation of thiamine pyrophosphate from ATP and thiamine. EC Restriction: Reduction in caloric intake without reduction in adequate nutrition. In experimental animals, caloric restriction has been shown to extend lifespan and enhance other physiological variables.Life Expectancy: Based on known statistical data, the number of years which any person of a given age may reasonably expected to live.Histamine Release: The secretion of histamine from mast cell and basophil granules by exocytosis. This can be initiated by a number of factors, all of which involve binding of IgE, cross-linked by antigen, to the mast cell or basophil's Fc receptors. Once released, histamine binds to a number of different target cell receptors and exerts a wide variety of effects.Ethanolamine: A viscous, hygroscopic amino alcohol with an ammoniacal odor. It is widely distributed in biological tissue and is a component of lecithin. It is used as a surfactant, fluorimetric reagent, and to remove CO2 and H2S from natural gas and other gases.Compulsive Behavior: The behavior of performing an act persistently and repetitively without it leading to reward or pleasure. The act is usually a small, circumscribed behavior, almost ritualistic, yet not pathologically disturbing. Examples of compulsive behavior include twirling of hair, checking something constantly, not wanting pennies in change, straightening tilted pictures, etc.Weight Lifting: A sport in which weights are lifted competitively or as an exercise.Egg Yolk: Cytoplasm stored in an egg that contains nutritional reserves for the developing embryo. It is rich in polysaccharides, lipids, and proteins.Subarachnoid Hemorrhage: Bleeding into the intracranial or spinal SUBARACHNOID SPACE, most resulting from INTRACRANIAL ANEURYSM rupture. It can occur after traumatic injuries (SUBARACHNOID HEMORRHAGE, TRAUMATIC). Clinical features include HEADACHE; NAUSEA; VOMITING, nuchal rigidity, variable neurological deficits and reduced mental status.Jumonji Domain-Containing Histone Demethylases: A family of histone demethylases that share a conserved Jumonji C domain. The enzymes function via an iron-dependent dioxygenase mechanism that couples the conversion of 2-oxoglutarate to succinate to the hydroxylation of N-methyl groups.Umbilical Veins: Venous vessels in the umbilical cord. They carry oxygenated, nutrient-rich blood from the mother to the FETUS via the PLACENTA. In humans, there is normally one umbilical vein.Receptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Infarction, Middle Cerebral Artery: NECROSIS occurring in the MIDDLE CEREBRAL ARTERY distribution system which brings blood to the entire lateral aspects of each CEREBRAL HEMISPHERE. Clinical signs include impaired cognition; APHASIA; AGRAPHIA; weak and numbness in the face and arms, contralaterally or bilaterally depending on the infarction.Brain Ischemia: Localized reduction of blood flow to brain tissue due to arterial obstruction or systemic hypoperfusion. This frequently occurs in conjunction with brain hypoxia (HYPOXIA, BRAIN). Prolonged ischemia is associated with BRAIN INFARCTION.Neurology: A medical specialty concerned with the study of the structures, functions, and diseases of the nervous system.Memory: Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.Neuropsychological Tests: Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.Memory Disorders: Disturbances in registering an impression, in the retention of an acquired impression, or in the recall of an impression. Memory impairments are associated with DEMENTIA; CRANIOCEREBRAL TRAUMA; ENCEPHALITIS; ALCOHOLISM (see also ALCOHOL AMNESTIC DISORDER); SCHIZOPHRENIA; and other conditions.Cognition Disorders: Disturbances in mental processes related to learning, thinking, reasoning, and judgment.Memory, Short-Term: Remembrance of information for a few seconds to hours.Annexin A2: A member of the annexin family that is a substrate for a tyrosine kinase, ONCOGENE PROTEIN PP60(V-SRC). Annexin A2 occurs as a 36-KDa monomer and in a 90-KDa complex containing two subunits of annexin A2 and two subunits of S100 FAMILY PROTEIN P11. The monomeric form of annexin A2 was formerly referred to as calpactin I heavy chain.Annexin A1: Protein of the annexin family exhibiting lipid interaction and steroid-inducibility.Annexin A6: Protein of the annexin family with a probable role in exocytotic and endocytotic membrane events.Annexin A4: Protein of the annexin family originally isolated from the electric organ of the electric ray Torpedo marmorata. It has been found in a wide range of mammalian tissue where it is localized to the apical membrane of polarized EPITHELIAL CELLS.Fatty Acids, Essential: Long chain organic acid molecules that must be obtained from the diet. Examples are LINOLEIC ACIDS and LINOLENIC ACIDS.Docosahexaenoic Acids: C22-unsaturated fatty acids found predominantly in FISH OILS.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Ascorbic Acid Deficiency: A condition due to a dietary deficiency of ascorbic acid (vitamin C), characterized by malaise, lethargy, and weakness. As the disease progresses, joints, muscles, and subcutaneous tissues may become the sites of hemorrhage. Ascorbic acid deficiency frequently develops into SCURVY in young children fed unsupplemented cow's milk exclusively during their first year. It develops also commonly in chronic alcoholism. (Cecil Textbook of Medicine, 19th ed, p1177)Fatty Acids, Unsaturated: FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds.Electronic Mail: Messages between computer users via COMPUTER COMMUNICATION NETWORKS. This feature duplicates most of the features of paper mail, such as forwarding, multiple copies, and attachments of images and other file types, but with a speed advantage. The term also refers to an individual message sent in this way.Spectrophotometry, Infrared: Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Journal Impact Factor: A quantitative measure of the frequency on average with which articles in a journal have been cited in a given period of time.Publishing: "The business or profession of the commercial production and issuance of literature" (Webster's 3d). It includes the publisher, publication processes, editing and editors. Production may be by conventional printing methods or by electronic publishing.

Role of class B scavenger receptor type I in phagocytosis of apoptotic rat spermatogenic cells by Sertoli cells. (1/2206)

Rat Sertoli cells phagocytose apoptotic spermatogenic cells, which consist mostly of spermatocytes, in primary culture by recognizing phosphatidylserine (PS) exposed on the surface of degenerating spermatogenic cells. We compared the mode of phagocytosis using spermatogenic cells at different stages of spermatogenesis. Spermatogenic cells were separated into several groups based on their ploidy, with purities of 60-90%. When the fractionated spermatogenic cell populations were subjected to a phagocytosis assay, cells with ploidies of 1n, 2n, and 4n were almost equally phagocytosed by Sertoli cells. All the cell populations exposed PS on the cell surface, and phagocytosis of all cell populations was similarly inhibited by the addition of PS-containing liposomes. Class B scavenger receptor type I (SR-BI), a candidate for the PS receptor, was detected in Sertoli cells. Overexpression of the rat SR-BI cDNA increased the PS-mediated phagocytic activity of Sertoli cell-derived cell lines. Moreover, phagocytosis of spermatogenic cells by Sertoli cells was inhibited in the presence of an anti-SR-BI antibody. Finally, the addition of high density lipoprotein, a ligand specific for SR-BI, decreased both phagocytosis of spermatogenic cells and incorporation of PS-containing liposomes by Sertoli cells. In conclusion, SR-BI functions at least partly as a PS receptor, enabling Sertoli cells to recognize and phagocytose apoptotic spermatogenic cells at all stages of differentiation.  (+info)

Kinetic and thermodynamic aspects of lipid translocation in biological membranes. (2/2206)

A theoretical analysis of the lipid translocation in cellular bilayer membranes is presented. We focus on an integrative model of active and passive transport processes determining the asymmetrical distribution of the major lipid components between the monolayers. The active translocation of the aminophospholipids phosphatidylserine and phosphatidylethanolamine is mathematically described by kinetic equations resulting from a realistic ATP-dependent transport mechanism. Concerning the passive transport of the aminophospholipids as well as of phosphatidylcholine, sphingomyelin, and cholesterol, two different approaches are used. The first treatment makes use of thermodynamic flux-force relationships. Relevant forces are transversal concentration differences of the lipids as well as differences in the mechanical states of the monolayers due to lateral compressions. Both forces, originating primarily from the operation of an aminophospholipid translocase, are expressed as functions of the lipid compositions of the two monolayers. In the case of mechanical forces, lipid-specific parameters such as different molecular surface areas and compression force constants are taken into account. Using invariance principles, it is shown how the phenomenological coefficients depend on the total lipid amounts. In a second approach, passive transport is analyzed in terms of kinetic mechanisms of carrier-mediated translocation, where mechanical effects are incorporated into the translocation rate constants. The thermodynamic as well as the kinetic approach are applied to simulate the time-dependent redistribution of the lipid components in human red blood cells. In the thermodynamic model the steady-state asymmetrical lipid distribution of erythrocyte membranes is simulated well under certain parameter restrictions: 1) the time scales of uncoupled passive transbilayer movement must be different among the lipid species; 2) positive cross-couplings of the passive lipid fluxes are needed, which, however, may be chosen lipid-unspecifically. A comparison of the thermodynamic and the kinetic approaches reveals that antiport mechanisms for passive lipid movements may be excluded. Simulations with kinetic symport mechanisms are in qualitative agreement with experimental data but show discrepancies in the asymmetrical distribution for sphingomyelin.  (+info)

Antibodies against phospholipids and oxidized LDL in alcoholic patients. (3/2206)

Antiphospholipid antibodies (APA) are a generic term describing antibodies that recognize various phospholipids. Hepatocyte damage is a cardinal event in the course of alcoholic liver injury and autoantibodies against phospholipids could play an important role in this process. APA in alcoholic patients seem to reflect membrane lesions, impairment of immunological reactivity, liver disease progression and they correlate significantly with disease severity. LDL oxidation is supposed to be one of the most important pathogenic mechanisms of atherosclerosis and antibodies against oxidized low-density lipoprotein (oxLDL) are some kind of an epiphenomenon of this process. The scope of our study was to determine some autoantibodies (IgG-oxLDL and antiphospholipid antibodies) and their possible changes in alcoholic patients. We studied IgG-oxLDL and four APA - anticardiolipin antibodies (ACA), antiphosphatidylserine antibodies (APSA) antiphosphatidylethanolamine antibodies (APE) and antiphosphatidylcholine antibodies (APCA) in 35 alcoholic patients with mildly affected liver function at the beginning of the abuse treatment. The control group consisted of 60 healthy blood donors. In the studied group, we obtained positive results concerning total ACA in 17.1 % of alcoholic patients (8.3 % in the control group), 11.4 % IgG-ACA (6.7 %), 8.6 % IgM-ACA (3.3 %), 14.3 % total APE (6.7 %), 14.3 % total APCA (8.3 %) and 20 % total APSA (8.3 % in the control group). The IgG-oxLDL (406.4+/-52.5 vs 499.9+/-52.5 mU/ml) was not affected in alcoholic patients. We conclude that the autoantibodies against oxLDL are present in sera of alcoholics and healthy blood donors. Based on our results which revealed a wide range of IgG-oxLDL titres in the healthy population, this parameter does not appear to be very promising for the evaluation of the risk of atherosclerosis. Alcoholics with only mild affection of liver functions did not exhibit a significantly higher prevalence of all studied antiphospholipid antibodies (ACA, APSA, APE, APCA) which could lead to membrane lesions in these patients.  (+info)

Plasmalogen status influences docosahexaenoic acid levels in a macrophage cell line. Insights using ether lipid-deficient variants. (4/2206)

Previously, this laboratory reported the isolation of variants, RAW. 12 and RAW.108, from the macrophage-like cell line RAW 264.7 that are defective in plasmalogen biosynthesis [Zoeller, R.A. et al. 1992. J. Biol. Chem. 267: 8299-8306]. Fatty acid analysis showed significant changes in the mutants in the ethanolamine phospholipids (PE), the only phospholipid class in which the plasmalogen species, plasmenylethanolamine, contributes significantly. Within the PE fraction, docosapentaenoic (DPA; 22:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids were reduced by approximately 50% in the variants while the levels of arachidonic acid (AA; 20:4n-6) remained unaffected. The decrease in DHA was accompanied by a 50% decrease in labeling PE with [3H]DHA over a 90-min period. Restoration of plasmenylethanolamine by supplementing the growth medium with sn -1-hexadecylglycerol (HG) completely reversed these changes in RAW. 108. Pre-existing pools of plasmenylethanolamine were not required for restoration of normal [3H]DHA labeling; addition of HG only during the labeling period was sufficient. Due to the loss of Delta1'-desaturase in RAW.12, HG supplementation resulted in the accumulation of plasmenylethanolamine's immediate biosynthetic precursor, plasmanylethanolamine. Even though this latter phospholipid contained only the ether functionality (lacking the vinyl ether double bond) it was sufficient to restore wild type-like fatty acid composition and DHA labeling of the ethanolamine phospholipids, identifying the ether bond as a structural determinant for this specificity. In summary, we have used these mutants to establish that the plasmalogen status of a cell can influence the levels of certain polyunsaturated fatty acids. These results support the notion that certain polyunsaturated fatty acids, such as DHA, can be selectively targeted to plasmalogens and that this targeting occurs during de novo biosynthesis, or shortly thereafter, through modification of nascent plasmalogen pools.  (+info)

Binding of annexin V to plasma membranes of human spermatozoa: a rapid assay for detection of membrane changes after cryostorage. (5/2206)

When the cell membrane is disturbed, phospholipid phosphatidylserine (PS) is translocated from the inner to the outer leaflet of the plasma membrane. This is one of the earliest signs of apoptosis and can be monitored by the calcium-dependent binding of annexin V. Therefore, annexin V-binding, in conjunction with flow cytometry, was used to evaluate the integrity of the sperm plasma membrane after different cryostorage protocols: i.e. 10% (v/v) glycerol; sperm maintenance medium (MM); freezing medium TEST yolk buffer (TYB); or cryostorage without protection (cryoshock). Using a combination of two fluorescent dyes, annexin V and propidium iodide (PI), led to three groups of spermatozoa being identified: (i) viable spermatozoa (annexin V-negative and PI-negative); (ii) dead spermatozoa (annexin V-positive and PI-positive); and (iii) cells with impaired but integer plasma membrane (annexin V-positive and PI-negative). The percentage of vital annexin V-negative spermatozoa increased significantly (P < 0.05) from spermatozoa treated by cryoshock (15.0+/-1.2%) to spermatozoa cryopreserved by TYB (26.6+/-2.2%) via cryopreservation by 10% (v/v) glycerol (19.9+/-1.6%) and by MM (22.2 1.8%) and was associated with the percentage of motile spermatozoa (17.6+/-3.4% by glycerol; 19.6+/-3.7% by MM and 22.6+/-3.9% by TYB; P = 0.0001). Of the spermatozoa, 12-22% were annexin V-positive even though they did not bind to PI, indicating viability before as well as after cryostorage. The percentage of vital annexin V-positive spermatozoa was significantly correlated with different sperm motility parameters (velocity straight linear, r = 0.601, P = 0.018; percentage of linearly motile spermatozoa: r = 0.549, P = 0.034). We, therefore, concluded that annexin V-binding is more sensitive in detecting a deterioration of membrane functions than PI staining, and that a considerable percentage of spermatozoa might have dysfunctional plasma membranes besides dead or moribund cells. Of the cryopreservation protocols tested, TYB yielded the most viable spermatozoa. Therefore, we advocate the use of the annexin V-binding assay for the evaluation of the quality and integrity of spermatozoa.  (+info)

Enhancement of endocytosis due to aminophospholipid transport across the plasma membrane of living cells. (6/2206)

Formation of intracellular vesicles is initiated by membrane budding. Here we test the hypothesis that the plasma membrane surface area asymmetry could be a driving force for vesicle formation during endocytosis. The inner layer phospholipid number was therefore increased by adding exogenous aminophospholipids to living cells, which were then translocated from the outer to the inner layer of the membrane by the ubiquitous flippase. Addition of either phosphatidylserine or phosphatidylethanolamine led to an enhancement of endocytosis, showing that the observed acceleration does not depend on the lipid polar head group. Conversely, a closely related aminophospholipid that is not recognized by the flippase, lyso-alpha-phosphatidylserine, inhibited endocytosis, and similar results were obtained with a cholesterol derivative that also remains in the plasma membrane outer layer. Thus an increase of lipid concentration in the inner layer enhanced internalization, whereas an increase of the lipid concentration in the outer layer inhibited internalization. These experiments suggest that transient asymmetries in lipid concentration might contribute to the formation of endocytic vesicles.  (+info)

Synthesis and turnover of cerebrosides and phosphatidylserine of myelin and microsomal fractions of adult and developing rat brain. (7/2206)

The synthesis and turnover of cerebrosides and phospholipids was followed in microsomal and myelin fractions of developing and adult rat brains after an intracerebral injection of [U-14C]serine. The kinetics of incorporation of radioactivity into microsomal and myelin cerebrosides indicate the possibility of a precursor-product relationship between cerebrosides of these membranes. The specific radioactivity of myelin cerebrosides was corrected for the deposition of newly formed cerebrosides in myelin. Multiphasic curves were obtained for the decline in specific radioactivity of myelin and microsomal cerebrosides, suggesting different cerebroside pools in these membranes. The half-life of the fast turning-over pool of cerebrosides of myelin was 7 and 22 days for the developing and adult rat brain respectively. The half-life of the slowly turning-over pool of myelin cerebrosides was about 145 days for both groups of animals. The half-life of the rapidly turning-over microsomal cerebrosides was calculated to be 20 and 40 h for the developing and adult animals respectively. The half-life of the intermediate and slowly turning-over microsomal cerebrosides was 11 and 60 days respectively, for both groups of animals. The amount of incorporation of radioactivity into microsomal cerebrosides from L-serine was greatly decreased in the adult animals, and greater amounts of the precursor were directed towards the synthesis of phosphatidylserine. In the developing animals, considerable amounts of cerebrosides were synthesized from L-serine, besides phosphatidylserine. The time-course of incorporation indicated that a precursor-product relationship exists between microsomal and myelin phosphatidylserine. The half-life of microsomal phosphatidylserine was calculated to be about 8 h for the fast turning-over pool in both groups of animals.  (+info)

Interaction between terminal complement proteins C5b-7 and anionic phospholipids. (8/2206)

We have recently shown that C5b-6 binds to the erythrocyte membrane via an ionic interaction with sialic acid before the addition of C7 and subsequent membrane insertion. In this study we assessed the role of anionic lipids in the binding of the terminal complement proteins to the membrane and the efficiency of subsequent hemolysis. Human erythrocytes were modified by insertion of dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylserine (DPPS), dipalmitoyl phosphatidylethanolamine (DPPE), or dipalmitoyl phosphatidic acid (DPPA). Lipid incorporation and the hemolytic assays were done in the presence of 100 micromol/L sodium orthovanadate to prevent enzymatic redistribution of lipid. We found that the neutral lipids, DPPC and DPPE, did not affect C5b-7 uptake or hemolysis by C5b-9. In contrast, the two acidic phospholipids, DPPS and DPPA, caused a dose-dependent increase in both lysis and C5b-7 uptake. We conclude that the presence of anionic lipids on the exterior face of the membrane increases C5b-7 uptake and subsequent hemolysis. It is known that sickle cell erythrocytes have increased exposure of phosphatidylserine on their external face and are abnormally sensitive to lysis by C5b-9. The data presented here provide a plausible mechanism for this increased sensitivity.  (+info)

  • Phosphatidylserine-dependent antiprothrombin antibodies (aPS/PT) were strongly correlated with the presence of lupus anticoagulant showing a high specificity for the diagnosis of antiphospholipid syndrome. (
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