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phospholipase a2 as a probe of phospholipid distribution in erythrocyte membranes. factors influencing the apparent specificity of the reaction.the action of snake venom phospholipases a2 in intact human erythrocytes was investigated in detail. the basis phospholipase from agkistrodon halys blomhifii was found to induce both hydrolysis of membrane phospholipids and total cell hemolysis under certain experimental conditions. the hydrolytic action of the basic enzyme was found to consist of two sequential events: (a) hydrolysis of 70% of the total cell ph osphatidylcholine without any evident hemolysis; and (b) complete hydrolysis of the ...197554
beta-bungarotoxin, a pre-synaptic toxin with enzymatic activity.beta-bungarotoxin, a pre-synaptic neurotoxin isolated from the venom of the snake bungarus multicinctus, has been shown to modify release of neurotransmitter at the neuromuscular junction. in this communication, we demonstrate that beta-bungarotoxin is a potent phospholipase a2 (phosphatide 2-acyl hydrolase, ec 3.1.1.4), comparable in activity with purified phospholipase enzymes from naja naja and vipera russellii. the phospholipase activity of beta-bungarotoxin requires calcium and is stimulate ...19761749
comparative cardiovascular and respiratory effects of bungarus fasciatus and naja naja siamensis venoms in dogs. 197826508
effect of purified phospholipases on the binding of tetrodotoxin to axon plasma membrane.the role of phospholipids in the binding of [3h]tetrodotoxin to garfish olfactory nerve axon plasma membrane was studied by the use of purified phospholipases. treatment of the membranes with low concentrations of either phospholipase a2 (crotalus adamanteus and naja naja) or phospholipase c (bacillus cereus and clostridium perfringens) resulted in a marked reduction in tetrodotoxin binding activity. a 90% reduction in the activity occurred with about 45% hydrolysis of membrane phospholipids by ...197939172
localization of a protein antigen in the chicken spleen. effect of various manipulative procedures on the morphogenesis of the germinal centre.the time course of the localization of a protein antigen human serum albumin (hsa) into the chicken spleen after intravenous injection is analysed. localization within seconds to the region surrounding the schweigger-seidel sheaths is accomplished by hsa complexes with chicken anti-hsa or by heat aggregated hsa. the localization of soluble hsa has to await the synthesis of sufficient chicken anti-hsa to accomplish localization to the same white pulp sites in the spleen at 25-30 hours after injec ...197546839
cobra venom factor: evidence for its being altered cobra c3 (the third component of complement).evidence is presented that cobra venom factor, the anticomplementary protein in naja naja venom, is modified cobra c3 (the third component of complement). antiserum to the cobra venom factor cross reacts with human c3. a protein in cobra serum reacts strongly with antiserum to the venom factor and the former protein, like human c3, is converted by incubation of cobra serum with endotoxin, hydrazine, or simple storage at 37 degrees c. incubation of cobra venom factor with cobra serum destroys the ...197656780
[production of antiserum to neurotoxin-2 from naja naja oxiana cobra venom and reaction with the toxin].antiserum to neurotoxin-2 from the venom of the cobra was obtained by immunization of rabbits via the injection of the toxin into the lymphatic nodes and by two re-immunizations via the injection of the toxin into the blood and intramuscularly. using scores of micrograms of the toxin, specific antisera with high antibody titer were obtained. in spite of high specificity of separate stages of the reactions, using indirect immune fluorescence technique, no specific fluorescence was found in the en ...197992118
preparation of highly potent naja naja atra (formosan cobra) antivenin.as the preparation of high titer antiserum against naja naja atra venom is a time-consuming process, attempts were made to develop a immunization procedure for producing highly potent antiserums within a short period. rabbits were immunized for 12 weeks with (1) whole venom as used routinely in our institute, (ii) whole venom adsorbed on carboxymethyl-cellulose (cmc) and mixed with freund's complete adjuvant and (iii) neurotoxin adsorbed on cmc and adjuvant mixture followed by cmc-whole venom-ad ...1978115651
production of potent antivenin against cobra venom with conjugated-cobrotoxin.cobra venom (naja naja atra) and its fractions obtained by ammonium sulfate precipitation were subjected to chromatography on cm-cellulose colum. a highly purified cobrotoxin obtained by the repeated chromatography on preparative cm-cellulose column was 6.7 times more toxic than the original cobra venom. the toxin was detoxified by a bifunctional reagent, glutaraldehyde, to about 99.8% and utilized for immunization in animals. mice received 4 weekly immunization with detoxified cobrotoxin and ch ...1979121068
inactivation of (na-++k-+)-stimulated atpase by a cytotoxic protein from cobra venom in relation to its lytic effects on cells.the mechanism of action of the cytotoxic protein p6 isolated from cobra venom (naja naja) which shows preferential cytotoxicity particularly to yoshida sarcoma cells has been studied by its effects on the membrane-bound enzyme (na-++k-+)-atpase (atp phosphohydrolase, ec 3.6.1.3) of a variety of cell systems. evidence obtained with yoshida sarcoma cells, dog and human erythrocytes and three tissue culture cell lines kb (human oral carcinoma), hela (human cervix carcinoma) and l-132 (human lung em ...1975124601
the effect of a cardiotoxic component of the venom of the indian cobra (naja nigricollis) on the subcellular structure and function of heart muscle. 1976133248
organization of phospholipids in human red cell membranes as detected by the action of various purified phospholipases.1. the action of eight purified phospholipases on intact human erythrocytes has been investigated. four enzymes, e.g. phospholipases a2 from pancreas and crotalus adamanteus, phospholipase c from bacillus cereus, and phospholipase d from cabbage produce neither haemolysis nor hydrolysis of phospholipids in intact cells. on the other hand, both phospholipases a2 from bee venom and naja naja cause a non-haemolytic breakdown of more than 50% of the lecithin, while sphingomyelinase c from staphyloco ...1975169915
poikilotherms as reservoirs of q-fever (coxiella burnetii) in uttar pradesh.water snakes (natrix natrix), rat snakes (ptyas korros), cobras (naja naja), pythons (python molurus), tortoises (kachuga sp.), plankton fish (cirrhina mrigala), frogs (rana tigrina), toads (bufo sp.) and monitors (varanus indicus) were screened for evidence of q-fever infection by the capillary agglutination test on sera to detect antibodies and/or by attempts to demonstrate coxiella burnetii in spleen and liver samples. sero-reactors were observed among water and rat snakes, pythons and tortoi ...1979459042
asymmetric manipulation of the membrane lipid bilayer of intact human erythrocytes with phospholipase a, c, or d induces a change in cell shape.changes in the membrane morphology and phospholipid content of human erythrocytes were determined after incubation of intact cells with each of various exogeneous phospholipases (plases). plase a2 from naja naja or bee venom induced crenation of the cells in parallel with hydrolysis of the membrane phosphatidylcholine (pc). this crenated cell shape was reversed to a biconcave disc or cup-like form by a further treatment with lysophospholipase. in contrast, bacterial plase c from clostridium perf ...1979521437
phospholipase a2 contamination of cobra venom factor preparations. biologic role in complement-dependent in vivo reactions and inactivation with p-bromophenacyl bromide.cobra venom factor (cof), the anticomplementary protein in naja naja cobra venom, is usually purified by sequential ion exchange and gel filtration chromatography. cof prepared in this manner contains small but significant quantities of phospholipase a2 activity. this acyl hydrolase activity can be simply and efficiently removed on a large scale by treatment of cof with p-bromophenacyl bromide (bpb), an irreversible modifier of the histidine residue in the active site of phospholipase a2. bpb tr ...1978655262
studies on neurotrophic regulation of murine skeletal muscle.1. a quantitative comparison was made of the effects of the paralysis caused by botulinum toxin (botx) type a with those of surgical denervation on the development of tetrodotoxin (ttx) resistant action potentials and of extrajunctional acetylcholine (ach) receptors in rat and mouse skeletal muscle.2. after surgical denervation, ttx resistant action potentials were present in all fibres on the third day and their rate of rise and amount of overshoot reached peak values at the fifth day. botx poi ...1978722508
neuromuscular effects of fractions isolated from the venom of the thailand cobra, naja naja siamensis. 1978725955
comparison of the nerve growth factor proteins from cobra venom (naja naja) and mouse submaxillary gland.the nerve growth factors (ngf's) isolated from cobra venom (naja naja) and mouse submaxillary gland are closely related proteins. they are structurally similar in that about 60% of their amino acid residues are identical (hogue-angeletti, r. a., frazier, w. a., jacobs, j. w., niall, h.d., and bradshaw, r. a. (1976), biochemistry, preceding paper in this issue). they are functionally similar in that they both elicit maximum neurite outgrowth from chick embryonic dorsal root ganglia at the same pr ...1976813760
inhibition of virus-induced plaque formation by atoxic derivatives of purified cobra neurotoxins.venom from naja naja siamensis was resolved into 16 toxic and nontoxic fractions by chromatography on sp-sephadex, c-25. the principal neurotoxin preparations were chromatographically and electrophoretically homogeneous. of the purified constituents, only the principal neurotoxin and minor neurotoxins were precursors of inhibitors of plaque formation among baby hamster kidney fibroblasts infected with semliki forest virus.1977836894
preparation of toxoids from the venoms of pakistan species of snakes. (naja naja, vipera russellii and echis carinatus). 1977875234
studies of nicotinic acetylcholine receptor protein from rat brain. ii. partial purification.the pharmacological specificity of the binding of 125i-labeled alpha-bungarotoxin to a 1% emulphogene bc-720 extract of a rat brain particulate fraction has been investigated. the extract contains a component which possesses the binding characteristics of a nicotinic acetylcholine receptor protein. the crude soluble acetylcholine receptor protein was purified by affinity chromatography utilizing the alpha-neurotoxin of naja naja siamensis as ligand and 1.0 m carbamylcholine chloride as eluant. a ...1977884157
nicotinic cholinergic receptors in rat brain identified by [125i]naja naja siamensis alpha-toxin binding. 1977890462
discrimination between nicotinic receptors in vertebrate ganglia and skeletal muscle by alpha-bungarotoxin and cobra venoms.1. we have used snake neurotoxins, alpha-bungarotoxin and venoms from naja naja siamensis and naja nivea, to distinguish the nicotinic receptors of ganglia from those of skeletal neuromuscular junctions. 2. these neurotoxins failed to block responses of isolated guinea-pig longitudinal muscle with adherent myenteric plexus to the nicotinic agonists, nicotine or dimethylphenylpiperazinium, to acetylcholine (ach), or to electrical field stimulation. 3. the toxins failed to affect responses of the ...1977894538
effects of aliphatic dicarboxylic acids on neuromuscular inhibition produced by naja naja siamensis toxin 3 and d-tubocurarine. 1977906030
comparative studies on cytotoxin from the indian cobra venom and cardiotoxin from the formosan cobra venom, with special reference to the effect on the growth of ehrlich ascites tumor cells in mice. 19761068210
blockade of acetylcholine receptors: a model of myasthenia gravis.in order to block acetylcholine receptors of muscle, the alpha toxin of the formosan cobra (naja naja atra) was given intravenously to rats. electrophysiological and pharmacological changes typical of myasthenia gravis were recorded, including decremental responses to repetitive stimuli, curare sensitivity, neostigmine reversal, and posttetanic phenomena. this model supports the concept that a reduction of available acetylcholine receptors may play an important role in myasthenia gravis.19751145181
amino acid sequence of cardiotoxin-analogue i from the venom of naja naja atra. 19751147930
evidence for endocytotic uptake of cobra neurotoxin in mouse skeletal muscle.an isolated 3h-labelled neurotoxin from naja naja siamensis binds irreversibly to the extensor digitorum longus muscle of the mouse in vitro. the binding consists of an adsorption to cholinergic receptors and of a slower temperature sensitive binding mechanism. the slow binding is markedly stimulated by the presence of cationic proteins (protamine, histone and polylysine) and is blocked at low temperature (+4 degrees c). vinblastine and colchicine inhibit the stimulatory effect of protamine on t ...19751159415
relation between various phospholipase actions on human red cell membranes and the interfacial phospholipid pressure in monolayers.the action of purified phospholipases on monomolecular films of various interfacial pressures is compared with the action on erythrocyte membranes. the phospholipases which cannot hyorolyse phospholipids of the intact erythrocyte membrane, phospholipase c from bacillus cereus, phospholipase a2 from pig pancreas and crotalus adamanteus and phospholipase d from cabbage, can hydrolyse phospholipid monolayers at pressure below 31 dynes/cm only. the phospholipases which can hydrolyse phospholipids of ...19751174576
the reaction of choline dehydrogenase with some electron acceptors.1. the choline dehydrogenase (ec 1.1.99.1) was solubilized from acetone-dried powders of rat liver mitochondria by treatment with naja naja venom. 2. the kinetics of the reaction of enzyme with phenazine methosulphate and ubiquinone-2 as electron acceptors were investigated. 3. with both electron acceptors the reaction mechanism appears to involve a free, modified-enzyme intermediate. 4. with some electron acceptors the maximum velocity of the reaction is independent of the nature of the accepto ...19751218095
topological asymmetry of phospholipid metabolism in rat erythrocyte membranes. evidence for flip-flop of lecithin.1. the distribution of phospholipids between inside and outside of rat erythrocyte membranes was studied by incubating the cells with phospholipase a2 from naja naja venom and sphingomyelinase from staphylococcus aureus. 2. choline-containing phospholipids were found to comprise the majority of the outer layer of the membrane. 3. the incorporation of radioactive fatty acids into phospholipids occurred predominantly at the inside of the membrane. 4. exchange of phospholipids between red cell memb ...19761245188
immunoglobulins in myasthenia gravis: effect of human lymph igg 3 and f (ab')2 fragments on a cholinergic receptor preparation from torpedo marmorata.lymph igg from patients with myasthenia gravis was shown to inhibit the binding of radio-labelled naja naja siamensis alpha-neurotoxin to membrane fragments from the electric organ of torpedo marmorata. this effect could be related to igg subclass 3 and to the f(ab')2 fragment. these findings confirm the involvement of antibodies of postsynaptic structures in myasthenia gravis.1977404156
acetylcholine receptors in the ciliary ganglion and in the iris muscle of the chick: specific binding and effect on the synaptic transmission of the neurotoxin from naja naja siamensis.1 a specific binding of naja naja siamensis neurotoxin was found both in the iris and in the ciliary ganglion of the chick. 2 naja-toxin (125 nm) caused a complete block of the iris muscle contraction induced by carbamylcholine. 3 naja-toxin had a different effect on the two neuronal populations present in the ganglion: it blocked the synaptically evoked response of the ciliary cells, while the response of the choroid ones was only slightly reduced. the effects were the same in a wide range of c ...1979222384
[pharmacokinetics of cytotoxin 14 from naja naja atra venom].the pharmacokinetics of cytotoxin 14 (ct 14) from naja naja atra venom was studied with biotin-avidin enzyme-linked immunosorbent assay. the plasma concentration-time curve of ct 14 after bolus i.v. 0.2 mg.kg-1 into rabbits was found to fit a two-compartment open model. t1/2 alpha was 5.8 +/- 0.6 min and t1/2 beta was 3.5 +/- 0.2 h. a rapid absorption was seen after im injection (0.5 mg.kg-1) to rabbits. the peak level was 260 +/- 90 ng.ml-1 and tpeak was 13.6 +/- 2.4 min. the absolute bioavaila ...19921302445
the absence of antagonism between extracts of clinacanthus nutans burm. and naja naja siamensis venom.clinacanthus nutans burm, a herb reputed in thailand and malaysia to be "snakebite antidote" has been tested in vitro and in vivo for antivenin activity. the aqueous extract of c. nutans leaves has been found to have no effect on the inhibition of neuromuscular transmission produced by purified naja naja siamensis neurotoxin in isolated rat phrenic-nerve diaphragm preparations. the extract of c. nutans, when given orally or intraperitoneally, are ineffective in prolonging the survival time of ex ...1977199949
the lipid requirement of the (ca2+ + mg2+)-atpase in the human erythrocyte membrane, as studied by various highly purified phospholipases.1. when complete hydrolysis of glycerophosphlipids and sphingomyelin in the outer membrane leaflet is brought about by treatment of intact red blood cells with phospholipase a2 and sphingomyelinase c, the (ca2+ + mg2+)-atpase activity is not affected. 2. complete hydrolysis of sphingomyelin, by treatment of leaky ghosts with spingomyelinase c, does not lead to an inactivation of the (ca2+ + mg2+)-atpase. 3. treatment of ghosts with phospholipase a2 (from either procine pancreas of naja naja veno ...1977137746
possible relationship between membrane proteins and phospholipid asymmetry in the human erythrocyte membrane.after incubation of human erythrocytes at 37 degrees c in the absence of glucose (a) for 24 h, (b) for 4 h with 8 mm hexanol or (c) for 3 h with sh reagents, phosphatidylethanolamine becomes partly susceptible to hydrolysis by phospholipase a2 from naja naja. the presence of glucose during the pretreatments suppresses this effect, except in the case of sh reagents that inhibit glycolysis. after incubation with tetrathionate, up to 45% of the phosphatidylethanolamine is degraded by the enzyme, an ...19761276220
purification, characterization, and partial amino acid sequence of nerve growth factor from cobra venom.the nerve growth factor (ngf) from naja naja (cobra) venom has been purified and its structure compared to the ngf from mouse submaxillary gland. a two-step purification procedure has been devised, consisting of a gel filtration step in 1 m acetic acid followed by chromatography of the active pool on carboxymethylcellulose at ph 5. the molecular weight of the native protein was found to be 28000, and this value was reduced by approximately one-half under denaturing conditions. these values are c ...19761247508
inhibition of phosphorylation of synapsin i and other synaptosomal proteins by beta-bungarotoxin, a phospholipase a2 neurotoxin.some snake venom neurotoxins, such as beta-bungarotoxin (beta-butx), which possess relatively low phospholipase a2 (pla2) activity, act presynaptically to alter acetylcholine (ach) release both in the periphery and in the cns. in investigating the mechanism of this action, we found that beta-butx (5 and 15 nm) inhibited phosphorylation, in both resting and depolarized synaptosomes, of a wide range of proteins, including synapsin i. naja naja atra pla2, which has higher pla2 activity, also inhibi ...19921431893
further studies on the binding properties of cobra neurotoxin to cholinergic receptors in mouse skeletal muscle.preparations of 3h-monoacetylated derivatives of naja naja siamensis neurotoxin siamensis 3 were found to be resistant to degradation and deacetylation during in vitro muscle incubation. a low rate of free 3h-acetate (less than 0.4%) was present in the preparations, but should not interfere with the binding of toxin to cholinergic receptors in mouse extensor digitorum longus muscles in vitro. the binding of toxin to cholinergic receptors in mouse extensor digitorum longus muscle was essentially ...19751185161
the cytotoxins of cobra venoms. isolation and partial characterization.eight basic proteins which lyse virus-transformed mouse fibroblasts in culture have been isolated from the venoms of six asian naja naja subspecies. these cytotoxins appear to represent an homologous series of proteins, all within the molecular weight range of 7000-8000. they have been divided into three arbitrary types on the basis of amino acid composition, electrophoretic mobilities and elution order upon ion-exchange chromatography. the rate at which the toxins effect cell lysis: (1) appears ...19751170892
effect of atropine in reducing plasma protein shedding by the canine oxyntic glandular mucosa induced by topical irrigation with histamine or cobra venom.the shedding of plasma protein by the canine oxyntic glandular mucosa induced by topical irrigation of the mucosa with a solution of histamine after the gastric mucosal barrier is broken is reduced by intravenous administration of atropine. plasma shedding induced by repeated irrigation of the normal mucosa with solutions of naja naja venom is likwise reduced by intravenous atropine. the nature of atropine-sensitive component of plasma shedding is unknown.19751150023
prevention and suppression by azathioprine of venom-induced protein-losing gastropathy in dogs.irrigation of the dog's oxyntic glandular mucosa contained in a chronically prepared, vagally denervated, separated pouch of the dog's stomach with a solution (0.5 mg ml-1) of lyophilized venom of the hooded cobra (naja naja) increases the permeability of the mucosa. if irrigation with venom solution is repeated at weekly intervals, the mucosa responds with increasing plasma-shedding which reaches a peak of 1-2 ml min-1 from roughly 60 cm2 of mucosa in 4-6 weeks. plasma shedding in response to i ...19761062810
nicotinic acetylcholine receptor from rat brain. solubilization, partial purification, and characterization.nicotinic acetylcholine receptor protein (nachr) has been solubilized from rat cerebral cortices by extracting a crude membrane fraction with the nonionic detergent triton x-100 (polyoxyethylene-p-t-octylphenol). the solubilized nachr was partially purified by affinity chromatography (naja naja siamensis alpha-toxin affinity arm, linked to sepharose 4b) and characterized by binding of 125i-labeled alpha-bungarotoxin. the reaction of labeled toxin and nachr appears to be second order with a rate ...1976977572
cinatrins, a novel family of phospholipase a2 inhibitors. ii. biological activities.cinatrins a, b and c3 inhibited phospholipase a2 purified from rat platelets in a dose-dependent manner. cinatrin c3, the most potent component (ic50 70 microm), was noncompetitive with a ki value of 36 microm. cinatrins b and c3 also inhibited both porcine pancreas and naja naja venom phospholipase a2. inhibition of rat platelet phospholipase a2 by cinatrin c3 was independent of ca2+ and substrate concentration. comparison with duramycin, another phospholipase a2 inhibitor, displayed inhibition ...19921548189
effects of local anaesthetics on phospholipases.1. the effects of six local anaesthetics have been studied on the activities of soluble phospholipases a2 (ec 3.1.1.4) and lysophospholipase (ec 3.1.1.5). 2. phospholipase a2 activity in human seminal plasma towards sonicated radioactively-labelled phosphatidylethanolamine was slightly stimulated a low and inhibited at high concentrations of all anaesthetic compounds employed. the order of decreasing potency was chlorpromazine, dibucaine, tetracaine, lidocaine, cocaine and procaine. in line with ...1976952985
differential hydrolysis of 1-alkyl-2-acyl and diacylglycerophosphocholines by human and non-human phospholipases a2.the activity of two human phospholipases a2, purified from synovial fluid and lumbar disc herniations, was tested using alkylacyl- and diacylglycerophosphocholines and the influence of the chemical link at the sn-1 position of glycerol was investigated. both enzymes exhibited 2.5-3-fold selectivity for 1-ester-linked compared to 1-ether-linked phosphatidylcholine. no significant selectivity was observed with pancreatic phospholipase a2 while naja naja naja venom enzyme was more efficient against ...19921576169
neuromuscular blocking actions of neurotoxins isolated from laticauda semifasciata, naja naja and naja naja atra--a comparative assay--. 1977916390
[biotin-avidin-elisa for cytotoxin purified from cobra venom].a technique combining the biotin-avidin amplifying system with sandwich enzyme-linked immunosorbent assay (b-a-elisa) was developed for the microassay of the cytotoxin from naja naja atra venom. the horse-peroxidase was used as the marker and polystyrene microhemagglutination plates as solid carrier. the sensitivity was 0.5 ng.ml-1. the assay range was 1.25-320 ngml-1 with coefficient of variation of 4.9% (intragroup) and 8.1% (intergroups), respectively.19921598840
interrelation between two anticomplement cobra venom factors isolated from crude naja naja cobra venom.two moieties occurring in crude naja naja cobra venom were found to possess anticomplement activity. both materials possessed similar molecular weights and specific activities but dissimilar elution profiles upon ion-exchange chromatography. the anticomplement activities of these materials were maintained upon digestion with neuraminidase, and their elution profiles from cation-exchange chromatography became identical after this treatment. it was concluded that the differences between the two an ...1977886456
reversibility of the activation of soluble phospholipase a2 on lipid bilayers: implications for the activation mechanism.the time-courses of hydrolysis of large vesicles of dipalmitoylphosphatidylcholine were compared using four species of phospholipase a2 (agkistrodon piscivorus piscivorus, crotalus adamanteus and naja naja venoms and porcine pancreatic). in all four cases, the hydrolysis rate suddenly increases 10 to 100-fold at the time (tau) when a specific mole fraction of reaction products has accumulated. the intrinsic fluorescence emission of the three venom enzymes also increases suddenly at time tau. bot ...19921643108
comparative effects of phospholipase a2 neurotoxins and enzymes on membrane potential and na+/k+ atpase activity in rat brain synaptosomes.beta-bungarotoxin (beta-butx) and notexin are phospholipase a2 (pla2) neurotoxins which cause an irreversible blockade of neurotransmitter release through specific and potent effects at the presynaptic nerve terminal; however, their mechanism of action is uncertain. we examined the effects of beta-butx and notexin on na+/k+ atpase activity using sprague-dawley rat brain synaptosomes in order to determine if alterations in activity might modulate neurotoxin-induced depolarization. treatment of sy ...19911648801
morphological study of lesions induced by snake venoms (naja naja and agkistrodon piscivorus) in the lung and cremaster vessels of rats.the morphological effects of two snake venoms, n. naja and a. piscivorus, and of the direct lytic factor and phospholipase-a, compounds purified from n. naja crude venom, were investigated on lung and cremaster vessels of rats. the microcirculation of the rat reacts to these two venoms differently: n. naja produces congestion, haemolysis and increased vascular permeability, whereas a. piscivorus causes these alterations, plus haemorrhage and thrombosis. direct lytic factor elicits reponses simil ...1977881630
primary structures of cardiotoxin analogues ii and iv from the venom of naja jaja atra.cardiotoxin analogues ii and iv were isolated from the venom of naja naja atra by gel filtration on sephadex g-50 followed by cm-cellulose chromatography. the venom contains at least four cardiotoxin analogues that account for about 54% of the weight of the lyophilized crude venom. these four cardiotoxin analogues, named cardiotoxin analogues i, ii, iii, and iv, show strong cytotoxicity to yoshida sarcoma cells but the lethal toxicity is one-order less. these toxins contain 60 amino acid residue ...1977849468
transverse asymmetry of phospholipids in subcellular membranes of rat liver.subcellular membranes isolated from rat liver in a form impermeable to macromolecules were treated with phospholipase a2 from naja naja venom. the phosphatidylserine, phosphatidylethanolamine and about half of the phosphatidylcholine of microsomes, golgi membranes, inner mitochondrial membranes, lysosomes and nuclear membranes were hydrolyzed. it is proposed that these phospholipids are localized in the outer surface of the membrane bilayer, which represents the cytoplasmic side in the living ce ...1977831804
phosphatidylcholine mobility in liver microsomal membranes.purified phosphatidylcholine exchange protein from bovine liver was used to exchange rat liver microsomal phosphatidylcholine for egg phosphatidylcholine. it was found that at 25 and 37 degrees c rat liver microsomal phosphatidylcholine was completely and rapidly available for replacement by egg phosphatidylcholine. in contrast, phosphatidylcholine in vesicles prepared from total microsomal lipids could only be exchanged for about 60%. at 8 and 0 degrees c complex exchange kinetics were observed ...1978667042
antiallergic and anti-inflammatory action of tioxamast in rats. i. antiallergic activity in vivo and in vitro.tioxamast (f 1865) is an antiallergic drug that, administered systemically, reduces anaphylaxis in various models in rats. this action is due mainly to the inhibition of the synthesis and release of certain mediators. orally or intraduodenally administered tioxamast inhibits ige-dependent passive cutaneous anaphylaxis (ed50 = 0.8 mg/kg), ige-dependent passive pulmonary anaphylaxis (ed50 = 0.5 mg/kg), and igg-dependent passive cutaneous anaphylaxis (ed50 = 0.6 mg/kg). it has little or not effect ...19901700967
primary structure and functional properties of cobra (naja naja naja) venom kunitz-type trypsin inhibitor.a trypsin inhibitor from the venom of the cobra naja naja naja has been isolated by a single step of reverse-phase high-performance liquid chromatography. the protein strongly inhibits trypsin (ki = 3.5 pm). the primary structure was determined by peptide analysis of the [14c]carboxymethylated inhibitor. the 57-residue polypeptide chain belongs to the family of kunitz-type inhibitors, and exhibits 42% residue identity with bovine pancreatic trypsin inhibitor. the structure shows only 70% identit ...19901702708
location of disulfide bridges in cardiotoxin from the venom of formosan cobra (naja naja atra).the location of the four disulfide bridges in cardiotoxin from the venom of the formosan cobra, naja naja atra, was determined by isolating cystine-containing peptides from the enzymic and partial acid hydrolyzates of the intact toxin. the results indicate that the disulfide bridges are formed by half cystine residues 3--21, 14--38, 42--53, and 54--59. the amino acid sequence at the position 48--49 was revised to -leu-val- instead of val-leu- as reported previously.1978649257
influence of enzymatic phospholipid cleavage on the permeability of the erythrocyte membrane. i. transport of non-electrolytes via the lipid domain.in order to further elucidate the influence of membrane lipids on transport via the lipid domain of the erythrocyte membrane, simple non-electrolyte diffusion was investigated by tracer flux measurements in whole cells after cleavage of up to 65% of phosphatidylcholine or sphingomyelin by phospholipase a2 from naja naja, or by sphingomyelinase. a new type of labelled model non-electrolyte was used in this study, readily available by reacting a non-labelled thiol with a labelled alkylating sh-rea ...1979486449
comparison of phospholipase activity with direct and indirect lytic effects of animal venoms upon human red cells.1. the venoms of 22 species of arthropods, saurians, elapids and crotalids were studied concerning the phospholipase activity and the presence of a direct and an indirect lytic effect upon human red cells. 2. the venoms from the spiders latrodectus and "tarantula", and the venoms from the scorpions of the genus centruroides are not haemolytic and do not have phospholipase activity. 3. only the venoms of apis mellifera and naja naja siamensis have shown direct lytic effect. 4. all other venoms st ...1979318305
antiflammins. anti-inflammatory activity and effect on human phospholipase a2.two anti-inflammatory peptides (antiflammins) corresponding to a high amino acid similarity region between lipocortin i and uteroglobin were tested for their ability to inhibit purified human synovial fluid phospholipase a2 (hsf-pla2). no inhibitory activity was observed, even at such high concentrations of peptides as 50 microm. when antiflammins were preincubated with the enzyme and/or the substrate, no hsf-pla2 inhibition was detected. in vivo anti-inflammatory activity of these peptides was ...19921387313
sphingolipid metabolism and signal transduction: inhibition of in vitro phospholipase activity by sphingosine.sphingosine inhibits protein kinase c activity in vitro and has been used to implicate this enzyme in signal transduction and cell function. we report that sphingosine directly inhibits phospholipases a2 and d. sphingosine inhibits ca(2+)-dependent phospholipases a2 from naja naja, porcine pancreas, crotalus adamanteus, human disc and neutrophil in a dose-dependent manner with ic50 values ranging from 5-40 microm using [1-14c]oleate-labelled autoclaved e. coli (20 microm) as substrate. inhibitio ...19921504102
morphological observations on motor end-plates in rabbits with experimental myasthenia.the morphology of motor end-plates in rabbits immunized with torpedo nicotinic acetylcholine receptor (nachr) has been studied by light and electron microscopy. rabbits were studied either after one period of paralysis, some in parallel with electrophysiological recordings of mepps and epps and of naja naja alpha-neurotoxin binding properties or after recovery followed by a second paralysis. changes in the sub-neural apparatus were noted after cholinesterase staining only in the latter group. ul ...1976978217
the markers of pig heart mitochondrial sub-fractions. ii. - on the association of malate dehydrogenase with inner membrane.malate dehydrogenase, reputed to be a soluble matricial enzyme, is shown to be also strongly associated with the inner membrane, in pig heart mitochondria. repeated sonications, water washes, freezing-thawing cycles are not very effective to remove malate dehydrogenase activity from inner membranes, which whatever the treatment, remains important. this activity is only partly solubilized by the substrates, malate or oxaloacetate. high ionic strength treatments by either nacl-carbonate or 3m kcl ...1978753379
the involvement of polymorphonuclear leukocytes in the pathogenesis of bronchopneumonia in calves. ii. granulocyte-induced changes in erythrocyte membrane phospholipid topology.phospholipid topology in erythrocyte membranes of bronchopneumonic calves and changes in phospholipid asymmetry induced by incubation of erythrocytes with neutrophils of diseased calves were examined. using aminophospholipid tracing by non-penetrating probe, trinitrobenzenesulfonic acid, and phospholipid hydrolysis by specific phospholipase a2 from naja naja venom and sphingomyelinase from staphylococcus aureus it was stated that in erythrocytes from diseased calves phosphatidylserine and, to so ...19911785438
effect of five thai snake venoms on coagulation, fibrinolysis and platelet aggregation.the effects of five thai snake venoms--malayan pit viper--mpv (ancistrodon rhodostoma); russell's viper--rvv (vipera russelli); cobra--cv (naja naja); king cobra--kcv (naja hannah) and banded krait--bkv (bungarus fasciatus)--on blood coagulation fibrinolysis and platelet aggregation were studied. mpv has strong thrombin-like coagulant action. rvv has activating effect most probably on factor x. other three venoms--cv, kcv and bkv have been shown to be anti coagulant, on both intrinsic and extrin ...1979524153
[1-14c]oleate-labeled autoclaved yeast: a membranous substrate for measuring phospholipase a2 activity in vitro.radiolabeled, autoclaved yeast were tested as a substrate for mammalian phospholipase a2 activity because the only other membranous substrate used for this purpose, autoclaved escherichia coli, totally lacks a major mammalian phospholipid, phosphatidylcholine. candida albicans were grown in the presence of [1-14c]oleate and then autoclaved. sixty three percent of the incorporated label was in yeast phospholipid, and more than 95% of that was in the 2-acyl position. the distribution of label in t ...19911872466
toxicities, ld50 prediction and in vivo neutralisation of some elapid and viperid venoms.toxicity levels of elapid (naja naja and naja oxiana) viperid (vipera lebetina and vipera russelli) venoms for mice and rat for intraperitoneal intravenous and intramuscular routes have been determined. the data have been analysed using a mathematical expression to calculate lethal venom concentrations in human snake bite cases. further, in vivo neutralisation of snake venom potency (after experimental injection) using high voltage-low current electric shock treatment has been attempted. this tr ...19921294479
[specific killing of human leukemic t-cells by a monoclonal antibody coupled to the cytotoxin from chinese cobra].the immunotoxin (it) was prepared by conjugating cytotoxin from chinese cobra (naja naja atra) venom with monoclonal antibody (mcab) wu71 directed to human t-cells. first, calcium ions were used to suppress the cytolytic reaction while cell antigen was allowed to react with mcab. then magnesium ions and the chelating agent egta were used to abolish the calcium inhibition. with this treatment, the it showed high cytotoxicity for the leukemic cell line cem, which was antigen positive (82.4% of the ...19921394735
lipopolysaccharide-induced stimulation of alveolar macrophage opsonin-independent phagocytosis.alveolar macrophage (am) opsonin-independent phagocytosis may be an important process by which bacteria are cleared from the airspaces. although it has been shown that clearance of bacteria from the lung is altered in association with endotoxemia, the effect of endotoxemia on opsonin-independent phagocytosis is unknown. because alterations in am opsonin-independent phagocytosis could potentially influence bacterial clearance in the lung, we studied the effects of the intravenous injection of esc ...19921405605
effects of snake venom phospholipase a2 toxins (beta-bungarotoxin, notexin) and enzymes (naja naja atra, naja nigricollis) on aminophospholipid asymmetry in rat cerebrocortical synaptosomes.the effects of snake venom phospholipase a2 (pla2) toxins (beta-bungarotoxin, notexin) and pla2 enzymes (naja nigricollis, naja naja atra) on aminophospholipid asymmetry in rat cerebrocortical synaptic plasma membranes (spm) were examined. incubation of intact synaptosomes with 2 mm 2,4,6-trinitrobenzene sulfonic acid (tnbs) for 40 min, under non-penetrating conditions, followed by spm isolation, allowed us to calculate the percentage of phosphatidylethanolamine (pe) and phosphatidylserine (ps) ...19921417932
a novel type of phospholipase a2 inhibitor, thielocin a1 beta, and mechanism of action.thielocin a1 beta, a novel phospholipase a2 inhibitor, was isolated from thielavia terricola rf-143. it inhibited various phospholipase a2s in a dose-dependent manner. among these, group ii phospholipase a2 from rat was most sensitive to thielocin a1 beta (ic50 = 0.0033 microm). the inhibition of phospholipase a2 by thielocin a1 beta was independent of ca2+ and substrate concentration. in addition, the inhibition of rat group ii phospholipase a2 was noncompetitive (ki = 0.0068 microm) and revers ...19921517154
preparation, characterization and immunogenicity of various polymers and conjugates of elapid postsynaptic neurotoxins.seven polymeric forms and conjugates of purified principal postsynaptic neurotoxins of naja naja siamensis (nns), ophiophagus hannah (oh) and bangarus fasciatus (bf) have been synthesized by controlled polymerization in which only 29-60% of the toxins were allowed to react. a carbodiimide (ecdi) and glutaraldehyde (ga) were used as coupling agents while bsa and tetanus toxoid (tt) were used as carriers. the antigenic mosaic of these immunogens was: nns-ecdi, nns-bf-oh-ecdi, nns-bsa-ecdi, nns-tt- ...19921565098
fusion of sphingomyelin vesicles induced by proteins from taiwan cobra (naja naja atra) venom. interactions of zwitterionic phospholipids with cardiotoxin analogues.egg sphingomyelin vesicles were used to assay aggregation/fusion activities of proteins from taiwan (naja naja atra) venom to avoid the problem of phospholipase a2 contamination during protein purification. it led to the identification of a new cardiotoxin (ctx) analogue protein (ctx v) with major aggregation/fusion, but few hemolysis, activities. on the contrary, cardiotoxin (ctx iii) induced significant hemolysis of human red blood cells but exhibited few aggregation/fusion activities. to stud ...19911993698
binding properties of pyrularia thionin and naja naja kaouthia cardiotoxin to human and animal erythrocytes and to murine p388 cells.pyrularia thionin and snake venom cardiotoxin are strongly basic peptides which induce hemolysis, depolarization of muscle cells and activation of endogenous phospholipase a2. an earlier study of the hemolysis reaction indicated that the two peptides bind to and compete for the same site on human erythrocytes. a recent study examined the hemolysis induced by both peptides as the phosphate and ca2+ content of the reaction mixture was varied. the results of the recent study (vernon, l. p. and roge ...19921509490
mojave toxin affects fusion of myoblasts and viability of myotubes in cell cultures.mojave toxin is a neurotoxic, heterodimeric phospholipase isolated from the venom of crotalus scutulatus scutulatus. responses of primary rat muscle cell cultures and clonal muscle cell lines to treatment with mojave toxin and its constituent subunits were examined. continuous exposure of cells to 0.5 microm or 1.0 microm mojave toxin or the basic subunit, added 24 hr after plating, prevented fusion of primary myoblasts and c2 myoblasts to multinucleate myotubes. under the same experimental cond ...19921509491
interleukin-1 alpha stimulates the release of prostaglandin e2 and phospholipase a2 from fetal rat calvarial cells in vitro: relationship to bone nodule formation.we have shown previously that interleukin-1 (il-1) has biphasic effects on the formation of bone nodules in long-term cultures of fetal rat calvarial (rc) cells (ellies and aubin, cytokine 2:430-437, 1990). to determine the role of arachidonic acid metabolism in this process, we have examined the release of prostaglandin e2 (pge2) and phospholipase a2 (pla2) from rc cells under conditions that allowed concomitant analysis of the formation of bone nodules. recombinant human il-1 alpha (rhil-1 alp ...19911785374
direct effects and augmentation of airway smooth muscle contraction caused by phospholipase a2.we examined the effect of phospholipase a2 (pla2; naja naja) on isometric tracheal smooth muscle force generation in guinea pig trachealis in situ. direct application of pla2 to the surface of the trachea caused dose-related contraction of tracheal smooth muscle. in seven guinea pigs, a dose/density of 100 micrograms/cm2 pla2 caused active tension (at) that began immediately and was maximum (1.32 +/- 0.13 g/cm) at 5 min (p less than 0.01 versus baseline tension). pla2 also augmented the contract ...19921596019
[pharmacological study on naja naja kaouthia lesson. iii. effects of 50% ethanolic extracts from liver and gall bladder on phagocytic activity of mouse reticuloendothelial system].effects of 50% ethanolic extracts from the liver and the gall bladder of naja naja kaouthia lesson (cob-l or cob-g) were studied on the phagocytic activity of a mouse reticuloendothelial system. the clearance-rate of carbon was shortened by the oral administration of cob-l or cob-g (50 or 200 mg/kg). cob-l or cob-g promoted the phagocytosis of latex by peritoneal macrophages (m phi). furthermore, effects of these extracts on the peritoneal m phi were biochemically investigated using in vitro exp ...19921608042
comparison of group i and ii soluble phospholipases a2 activities on phagocytic functions of human polymorphonuclear and mononuclear phagocytes.soluble phospholipase a2 (pla2) purified from rheumatoid synovial fluid (group ii) and repurified naja naja venom pla2 (group i) were compared for their influence on phagocytic activity of human polymorphonuclear (pmn) and mononuclear (mo) phagocytes. group ii pla2 reduced chemotaxis, adhesiveness, and intracellular bactericidal activity (icba) and induced release of muramidase from pmns. group i pla2 suppressed chemotaxis, and enhanced icba but had no influence on other phagocytic functions. gr ...19911649131
effects of a cardiotoxin from naja naja kaouthia venom on skeletal muscle: involvement of calcium-induced calcium release, sodium ion currents and phospholipases a2 and c.snake venom cardiotoxin (ctx) fractions induce contractures of skeletal muscle and hemolysis of red blood cells. the fractions also contain trace amounts of venom-derived phospholipase a2 (pla2) contamination and activate tissue phospholipase c (plc) activity. the present study examines the mechanisms of action of a ctx fraction from naja naja kaouthia venom in skeletal muscle. sphingosine competitively antagonized ctx-induced red blood cell hemolysis, but not skeletal muscle contractures. ctx r ...19911666202
effects of anti-inflammatory drugs on rat hind-paw swelling caused by phospholipase a2 from naja naja atra venom.rat hind-paw swelling was induced dose-dependently by subplantar injection of acidic phospholipase a2 (nnavpla2) from naja naja atra venom. diphenhydramine and methysergide pretreatment greatly reduced the swelling effect caused by nnavpla2. several doses of compound 48/80 given to deplete the histamine content of rat hind paw, also greatly suppressed nnavpla2-induced paw swelling. the paw swelling caused by nnavpla2 was reduced following pretreatment with bw 755c, a dual inhibitor of cyclooxyge ...19911683689
comparison of the enzymatic and edema-producing activities of two venom phospholipase a2 enzymes.the edema-producing activity of nnavpla2, an acidic phospholipase a2 (pla2) enzyme from naja naja atra venom (nnav), was less potent than that of tmvpla2 ii, a basic pla2 from trimeresurus mucrosquamatus venom (tmv). these edema-forming effects were greatly suppressed by pretreatment of rats with diphenhydramine/methysergide or compound 48/80, which reduced the tissue content of histamine and serotonin. heparin abolished and suppressed the paw edema caused by protamine and tmvpla2 ii, respective ...19901703083
intracellular mechanisms involved in short-term regulation of net protein synthesis in pancreatic acini.the mechanisms regulating the net synthesis of digestive enzymes during short-term stimulation by agonists were examined in pancreatic acini isolated from the rat. dispersed pancreatic acini were stimulated for up to 60 min with various concentrations of cholecystokinin octapeptide (cck-op), carbachol, a23187, 4 beta-phorbol 12-myristate 13-acetate (pma). the effects of these agonists on net protein synthesis was determined by measuring the incorporation of [3h]leucine or [35s]methionine into pr ...19911708286
phospholipase a2-induced pulmonary and hemodynamic responses in the guinea pig. effects of enzyme inhibitors and mediators antagonists.the effect of phospholipase a2 (naja naja) pla2) on mean arterial blood pressure and intratracheal pressure was examined in anesthetized guinea pigs. intracheally administered pla2 (1 to 10 u) produced acute, dose-dependent increases in mean arterial blood pressure and intracheal pressure. however, intravenously administered pla2 (doses as large as 1,000 u) did not alter monitored variables. acute pla2-induced morphologic alterations were characterized by airway constriction, airway/alveolar cel ...19902240843
acute lung injury induced by phospholipase a2. structural and functional changes.on the basis of the observation that serum levels of phospholipase a2 (pla2) are elevated in pancreatitis and systemic sepsis, and the association of these conditions with the subsequent development of acute lung injury, the present investigation examined the structural and physiologic consequences of intratracheal administration of pla2 to adult male rats. rats received direct intratracheal instillation of either control vehicle or 40,000 units/kg of pla2 repurified from naja naja venom. animal ...19911902636
renaturation of cobra venom phospholipase a2 expressed from a synthetic gene in escherichia coli.cobra venom (naja naja naja) phospholipase a2 (pla2) contains 14 cysteines in the form of 7 disulfide bonds amongst its 119 amino acids. a gene encoding the pla2 was synthesized and inserted into a bacterial expression vector containing the phage lambda pl promoter. in order to obtain protein without the initiating methionine at the n-terminus, a factor xa site was engineered upstream from the pla2 gene. upon heat-induction of the cells transformed with the expression plasmid, the protein is pro ...19921730025
absence of lung reactions after complement depletion during dialysis: an experimental study in pigs.sequestration of 111in-labeled neutrophils (polymorphonuclear leukocytes--pmns) in the lungs during sham dialysis was studied dynamically using a gamma camera. five animals were pretreated with cobra venom factor, naja naja (cvf), to achieve depletion of the complement system, mainly c5a. seven animals were studied without pretreatment with cvf. central hemodynamics and gas exchange were studied as well as neutrophil function using luminescence and aggregation. in the control group there was a s ...19911741685
identification of a crotoxin-binding protein in membranes from guinea pig brain by photoaffinity labeling.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 d ...19902341382
kinetic characterization of phospholipase a2 modified by manoalogue.manoalogue, a synthetic analogue of the sea sponge-derived manoalide, has been previously shown to partially inactivate the phospholipase a2 from cobra venom (reynolds, l. j., morgan, b. p., hite, e. d., mihelich, e. d., & dennis, e. a. (1988) j. am. chem. soc. 110, 5172) by reacting with enzyme lysine residues. in the present study, the inactivation of the phospholipases a2 from pig pancreas, bee venom, and cobra (naja naja naja) venom by manoalogue was studied in detail. manoalogue-treated enz ...19911911741
effect of anti-inflammatory drugs on the cardiotoxin-induced hind-paw oedema in rats.cardiotoxin, isolated from naja naja atra venom, induced rat hind-paw oedema. this effect was suppressed by the pretreatment with dexamethasone or bw 755c, or subplantar co-injection with fpl 55712. pretreatment with aspirin alone did not affect this response, while a significant reduction of cardiotoxin-induced paw oedema was achieved with aspirin in combination with diphenhydramine and methysergide. subplantar co-injection of paf antagonist, bn 52021 or l 652731, with cardiotoxin had no effect ...19901983146
development of an elisa to assess the potency of horse therapeutic antivenom against thai cobra venom.an elisa for the quantitation of antibodies against naja naja siamensis venom proteins has been developed for use as a possible replacement for the in vivo neutralization assay of antivenom potency. comparison was made with three preparations of venom proteins as antigens of elisa: these were the crude venom, a toxin fraction and the purified principle postsynaptic neurotoxin of the thai cobra. eight batches of horse monovalent therapeutic anti-cobra antivenom, one of which served as positive re ...19911995711
structure-function relationships among neurotoxic phospholipases: nn-xiii-pla2 from indian cobra (naja naja naja) and vrv pl-v from russell's viper (vipera russelli) venoms.though venom phospholipases induce various pharmacological effects their mechanism of action is in some cases unclear. there may be separate pharmacological sites on the venom phospholipase molecule. in order to understand the structure-function relationships among venom phospholipases, studies on interaction of venom phospholipases with its antibodies and various alkaloids were carried out. the alkaloids aristolochic acid, ajmaline and reserpine were incapable of inhibiting the phospholipase a2 ...19912028476
comparative enzymatic composition of brazilian coral snake (micrurus) venoms.1. venoms of 11 coral snake taxa, including micrurus albicinctus, m. corallinus, m. frontalis altirostris, m. f. brasiliensis, m. f. frontalis, m. fulvius fulvius, m. ibiboboca, m. lemniscatus ssp., m. randonianus, m. spixii spixii, and m. surinamensis surinamensis, were examined for 13 enzymatic activities. 2. these were compared with venoms of three outgroup taxa: naja naja kaouthia, bungarus multicinctus, and bothrops moojeni. 3. enzyme activity levels in micrurus venoms were highly variable ...19911662592
comparison of the catalytic properties of phospholipase a2 from pancreas and venom using a continuous fluorescence displacement assay.phospholipases a2 from pig pancreas and the venoms from bee, naja naja and crotalus atrox have been studied by using a new continuous fluorescence displacement assay that utilizes normal phospholipid substrates [wilton (1990) biochem. j. 266, 435-439]. with limiting amounts of substrate, the assay demonstrated stoichiometric conversion into products with both pancreatic and venom enzymes, and thus would allow phospholipid determination at concentrations down to about 0.1 microm. the substrate sp ...19911898370
extracellular phospholipase a2 and histamine release from rat peritoneal mast cells.phospholipase a2 (pla2) from cobra (naja naja) venom and pla2 from porcine pancreas accelerated ige antibody-mediated histamine release from rat peritoneal mast cells. these enhancements were clearly abrogated by heating the enzymes and pretreatment with parabromophenacyl bromide, mepacrine and antiflammin. indomethacin (cyclooxygenase inhibitor) and aa-861 (lipoxygenase inhibitor) did not affect the enhancement by pla2. these results indicate that extracellular pla2 enhances the ige antibody-me ...19911725674
isolation and fundamental characteristics of a phospholipase b inhibitor from autolyzed torulaspora delbrueckii.phospholipase b inhibitor was found in the autolyzate of yeast cells, torulaspora delbrueckii. the inhibitor was purified to homogeneity by ethanol precipitation, gel filtration with sephadex g-10, ion-exchange chromatography with deae-sephacel, and gel filtration with asahipak gs-320. on thin-layer chromatography the purified inhibitor was detected with the hanes-isherwood reagent, which is used to detect phosphorus. the activity of the inhibitor was not affected by heat treatment at 100 degree ...19911760134
monoclonal antibodies against vipera lebetina venom nerve growth factor cross-react with other snake venom nerve growth factors.nerve growth factor (ngf) was isolated from the venom of vipera lebetina and was purified to homogeneity as judged by sds gel electrophoresis. the biologically active ngf was used to immunize balb/c mouse, and the spleen cells from immunized mouse were fused with mouse pai myeloma cells. forty-seven hybrid cell lines, secreting monoclonal antibodies to v. lebetina ngf, were isolated and nine of them purified from ascitic fluids. the isolated antibodies define two partially overlapping epitopes o ...19872448608
pharmacological study of phospholipase a2-induced histamine release from rat peritoneal mast cells.the effect of some drugs on phospholipase a2 (pla2)-induced histamine release from rat peritoneal mast cells was investigated. 1. pla2 (naja naja) caused the release of histamine from rat peritoneal mast cells in a dose related fashion. 2. the release of histamine by pla2 was decreased by the removal of each of calcium and glucose from the reaction medium (tyrode's solution). 3. p-bromophenacyl bromide and mepacrine, pla2 inhibitors, inhibited the release of histamine caused by pla2. 4. cinnariz ...19892482349
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