Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antigenic and allergenic properties of phospholipase A2 (PLA2) and whole bee venom were compared by measuring the IgG and IgE antibody responses in animals and man. Precipitating antibodies raised in rabbits and reaginic and other antibodies raised in mice reacted about equally with both bee venom and PLA. The majority of human sera containing bee venom-specific IgE also contained PLA-specific IgE, although in somewhat lower titers. Similarly, most human sera with significant amounts of total antibodies reacting with bee venom also had antibodies reacting with PLA. Histamine and SRS-a release from leukocytes of sensitive patients followed challenge with whole bee venom and PLA in the majority of instances. However, mediator release from several patients' cells was obtained with bee venom only. These studies suggest that although PLA is a major allergen and antigen in bee venom, significant exceptions in patients' reactivity may limit its potential diagnostic and therapeutic usefulness.
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PMID:Studies of the antigenicity and allergenicity of phospholipase A2 of bee venom. 5 45

Using a perfused rat hindleg system, release of tissue-type plasminogen activator (t-PA) from endothelial cells could be induced by platelet-activating factor (PAF), bradykinin, substance P, thrombin, carbachol and A23187, while this release was inhibited by mepacrine and by nor-dihydroguaiaretic acid. The PAF-induced release of t-PA was inhibited by the cytochrome P-450 mono-oxygenase inhibitors, metyrapone, ketoconazole and SKF 525A and by eicosatetraynoic acid but not by indomethacin or BW 755C, suggesting the involvement of epoxygenase products. The PAF-induced release of von Willebrand factor (vWF) was also similarly inhibited by the cytochrome P-450 monooxygenase inhibitor, ketoconazole. Phorbol ester and phospholipase C induced the release of both t-PA and vWF, while phospholipase A2 did not. The release induced by PAF and bradykinin was not influenced by pretreatment with pertussis toxin.
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PMID:The involvement of products of the phospholipase pathway in the acute release of tissue-type plasminogen activator from perfused rat hindlegs. 152 62

The current risk of disease transmission through homologous blood transfusion has lead to a revival in the use of autologous blood. The development of a coagulopathy increases the usage of blood and blood products and therefore the risk of disease transmission. Blood salvaged at operation is subjected to physical and humoral activating factors. The potential systems to be activated are located either in the plasma or non red cell cellular elements. Homologous blood and blood salvaged at operation before and after washing was examined for activation of the plasma and cellular systems by measuring the presence of fibrin degradation products (xDP's), activated complement (C3a) and plasminogen activator and inhibitor activity from the plasma systems; and elastase, serotonin, lysophospholipids, leukotriene B4, lysoplatelet factor and phospholipase A2 from the cellular systems. The plasma systems were activated in the salvaged blood which had elevated levels of xDP's and C3a compared to the patient's blood (p less than 0.05). The products of cellular activation were also elevated in operatively salvaged blood (p less than 0.01 for all the above products). The levels xDP's were normal but the levels of C3a increased in stored blood. The levels of the cellular systems, elastase, serotonin and lysoplatelet activating factor, increased with the duration of storage of bank blood. Unwashed and aged stored blood contains potentially harmful products. Consideration should be given to removal of non red cell elements in blood stored for surgery.
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PMID:The quality of blood used for transfusion. 154 6

We compared the diagnostic and prognostic utility of phospholipase A (PLA; EC 3.1.1.4) for acute pancreatitis with that of amylase and lipase by analysis of sera from 151 consecutive patients presenting with abdominal pain in whom assays of serum amylase and (or) lipase had been ordered. We determined the diagnostic accuracy for both the initial and the peak enzyme activities. Maximal diagnostic accuracy obtained for the initial activities of amylase, lipase, and PLA was 0.83, 0.83, and 0.76 at cutoff values of 650, 650, and 41 U/L, respectively. Use of peak enzyme activities showed maximal diagnostic accuracy of 0.85, 0.86, and 0.73 at cutoff values of 650, 1050, and 42 U/L, respectively. Receiver-operator characteristic curve analysis revealed the diagnostic performance of amylase and lipase to be similar, whereas that of PLA was almost random and not incremental. As with amylase and lipase, PLA activities in sera showed no relation to patients' survival; three patients who died after an attack of acute pancreatitis failed to demonstrate the dramatic increases in PLA activity previously described. We conclude that assessing the severity of acute pancreatitis by using enzyme activities still remains problematical. Measurements of amylase or lipase activities provide similar diagnostic discrimination when appropriate cutoff values are used and remain the methods of choice for diagnosis of acute pancreatitis.
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PMID:Diagnostic and prognostic utility of phospholipase A activity in patients with acute pancreatitis: comparison with amylase and lipase. 191 91

Proteose peptone (p.peptone) had an ability to induce tissue plasminogen activator (t-PA) production by human embryonic lung fibroblast, IMR-90 cells. We previously demonstrated that the induction was closely related to the activation of phospholipase A2 in the cells stimulated by p.peptone. In this report, we describe the involvement of arachidonate metabolism in the induction. The induction was inhibited in a dose-dependent manner by 5,8,11,14-eicosatetraenoic acid (ETYA), an inhibitor of both cycloxygenase and lypoxygenase, and also by nordihydroguaiaretic acid (NDGA), which in low concentrations selectively inhibits lipoxygenase. However, indomethacin, a specific inhibitor of cycloxygenase, had no effect on the induction. 5-hydroxyeicosatetraenoic acid (5-HETE), which is an arachidonate metabolite derived from lipoxygenase pathway, had an inductive effect, but prostaglandin E1 (PGE1), which is a metabolite from cycloxygenase pathway, had no effect on t-PA production by the cells. These results suggest that arachidonate metabolism is involved in the induction of t-PA production in IMR-90 cells by p.peptone, and that arachidonate metabolite(s) from lipoxygenase pathway is responsible for the induction.
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PMID:Possible roles of arachidonic acid and its metabolites in induction of tissue plasminogen activator (t-PA) production in human fibroblast, IMR-90 cells by proteose peptone. 173 58

The effects of tranexamic acid, an inhibitor of plasminogen activator, were evaluated in a rabbit model of osteoarthritis induced by section of the knee joint anterior cruciate ligament. Prophylactic treatment administered intramuscularly thrice weekly for 12 or 24 weeks significantly reduced cartilage destructive lesions, increased cartilage hypertrophy but did not prevent changes in cartilage water and proteoglycan content. A suppression of synovial membrane stromelysin and collagenase activity was found while phospholipase A2 activity was unaffected.
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PMID:Study of an inhibitor of plasminogen activator (tranexamic acid) in the treatment of experimental osteoarthritis. 185 Dec 28

We recently proposed that arachidonic acid serves as a second messenger within granulosa cells from the largest preovulatory follicle of the hen. The present studies were conducted to determine whether the inhibitory effects of arachidonic acid on LH-induced cAMP accumulation and on the ability of cells to convert 25-hydroxycholesterol to progesterone are mediated via the protein kinase C pathway. Furthermore, we determined the effects of arachidonic acid on plasminogen activator activity in granulosa cells. In the first experiment, the putative protein kinase C inhibitor, staurosporine, completely reversed the inhibitory effects of phorbol 12-myristate 13-acetate (PMA) on LH-promoted cAMP formation, but failed to overcome the inhibitory effects of arachidonic acid. Prolonged pretreatment (18 h) with 1.6 microM PMA depleted granulosa cells of both cytosolic and membrane-associated protein kinase C, and subsequently attenuated the inhibitory effects of PMA on LH-induced progesterone production; however, such depletion did not alter the inhibitory effects of phospholipase A2 (PLA2; an agent that increases intracellular levels of arachidonic acid). PMA, but not arachidonic acid, caused a rapid (within 2 min) translocation of protein kinase C from the cytosol to the membrane (a characteristic of agents that activate protein kinase C). Finally, both arachidonic acid and PLA2 inhibit plasminogen activator (PA) activity in a dose-dependent fashion, whereas activation of protein kinase C with PMA stimulates PA activity. Taken together, the data suggest that the effects of arachidonic acid in granulosa cells can occur independently of protein kinase C activation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Evidence that arachidonic acid influences hen granulosa cell steroidogenesis and plasminogen activator activity by a protein kinase C-independent mechanism. 196 26

The Escherichia coli outer-membrane phospholipase A (OM PLA) is a membrane-bound acyl hydrolase with a broad substrate specificity. In order to obtain more insight into the mechanism of action of this enzyme, we designed an active-site-directed inhibitor for OM PLA on the basis of the known substrate specificity as a first step in the elucidation of the catalytic mechanism of this enzyme. The inhibitor, hexadecanesulfonyl fluoride, consists of a long hydrocarbon chain for high-affinity binding by the enzyme and a sulfonyl fluoride moiety as a reactive group. The kinetics of the inactivation of OM PLA by hexadecanesulfonyl fluoride were studied in Triton X-100 micelles. Inactivation is very fast, specific and shows the same characteristics with respect to acyl specificity, pH profile and metal ion requirement as the activity of OM PLA on substrates. Incubation of OM PLA with a stoichiometric amount of hexadecanesulfonyl fluoride leads to a total and irreversible loss of enzyme activity, resulting from the sulfonylation of Ser144. This Ser144, which we suggest to be the active-site serine of OM PLA, is part of the sequence HDSNG, whereas in the water-soluble serine proteases and lipases the structural motif GXSXG is normally encountered. On the basis of the kinetics of inactivation of OM PLA by hexadecanesulfonyl fluoride, we discuss a possible catalytic mechanism of the enzyme.
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PMID:Inactivation of Escherichia coli outer-membrane phospholipase A by the affinity label hexadecanesulfonyl fluoride. Evidence for an active-site serine. 204 Feb 86

Crotoxin is a neurotoxic phospholipase A2 capable of blocking synaptic transmission by inhibiting the release of neurotransmitters. The photoaffinity labeling technique was used to identify the neural membrane molecules involved in the binding of crotoxin. A photoactivatable, radioactive derivative of crotoxin was synthesized by reacting crotoxin with N-hydroxysuccinimidyl-4-azidobenzoate and with Na[125I]. Photoirradiation of synaptosomes from guinea pig brains in the presence of the crotoxin derivative resulted in the formation of a major radioactive conjugate of 100,000 daltons as revealed by autoradiography of a sodium dodecyl sulfate-polyacrylamide gel electrophoretic pattern. Pretreatment of the synaptosomes with trypsin, Staphylococcus aureus protease, or papain prevented the formation of this conjugate. The conjugate was not detected when plasma membranes from several nonneural tissues replaced the brain synaptosomes. Unmodified crotoxin inhibited the formation of this adduct with an IC50 of about 10(-8)M. Mojave toxin, caudoxin, notexin, Naja naja PLA, and taipoxin also inhibited adduct formation with different potencies, while beta-bungarotoxin and pancreatic PLA were ineffective. We concluded that an 85,000-dalton protein is the major component responsible for the binding of crotoxin to synaptosomal membranes.
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PMID:Identification of a crotoxin-binding protein in membranes from guinea pig brain by photoaffinity labeling. 234 82

1. The major phospholipase A2 (PLA-DE4) of the venom of Trimeresurus purpureomaculatus (shore pit viper) has been purified to electrophoretic homogeneity. 2. The isoelectric point of the purified enzyme was determined to be 4.20, and the mol. wt was 31,700 as estimated by Sephadex G-75 gel filtration chromatography; and 14,000 as estimated by SDS-polyacrylamide gel electrophoresis. The purified enzyme hydrolyzed phosphatidylcholine (PC) faster than phosphatidylethanolamine (PE), whereas phosphatidylserine (PS) was not hydrolyzed at all (PC greater than PE greater than PS =0). However, in reaction system consisted of mixtures of PC and PS, phosphatidylserine was effectively hydrolyzed by the enzyme. 4. The phospholipase A2 exhibited edema-forming activity but not hemolytic, hemorrhagic or anticoagulant activities. It was not lethal to mice at a dosage of 10 micrograms/g by i.v. route.
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PMID:Isolation and characterization of the major phospholipase A2 from the venom of Trimeresurus purpureomaculatus (shore pit viper). 261 28


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