SEARCH · PubMed Health

Results for “Vipera”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1980

Orthograde and retrograde axonal movement of label and transneuronal transport phenomena after intraocular injection of [3H]adenosine in a poikolotherm vertebrate (Vipera aspis).

The axoplasmic transport of [3H]adenosine (or its related compounds) has been examined radioautographically in the visual system of a poïkilotherm species (Vipera aspis) following an intraocular injection of the nucleoside. It has been found that the axonal transport of the label occurs both in the anterograde directions. Furthermore, a considerable labelling of neuronal bodies as a result of transneuronal transport of tritiated material from the optic endings has been observed, particularly in the primary optic centers. Transneuronal labelling, however, appears less intense than retrograde cell labelling.

Adenosine↗

PubMed1987

Purification and properties of a proteinase from Vipera lebetina (snake) venom.

A proteinase from the venom of Vipera lebetina was purified by chromatography on Sephadex G-100 and CM-cellulose. The purified proteinase was homogeneous on SDS-polyacrylamide gel electrophoresis and consisted of a single chain with molecular weight of 37,000 +/- 1500. The isoelectric point of the proteinase was over 10. The enzyme was active on casein but not on esters and amides of arginine. It split the oxidized insulin B-chain at the peptide bonds of Tyr16-Leu17, Phe24-Phe25 and Phe25-Tyr26, and glucagon at the bonds Tyr10-Ser11, Leu14-Asp15 and Leu26-Met27. The enzyme was inhibited by DFP and PMSF, and partially by soybean trypsin inhibitor, but not with EDTA.

Amino Acids↗

PubMed1991

Purification and characterization of lebetase, a fibrinolytic enzyme from Vipera lebetina (snake) venom.

An anticoagulant proteinase, lebetase, was isolated from the venom of Vipera lebetina by gel filtration and anion-exchange chromatography. The proteinase consists of a single polypeptide chain with a molecular weight of 23,700. Amino acid analysis indicates that lebetase contains 214 residues. It consists of several isoforms in the pH range 4.6-5.4, all having fibrinolytic activity. Lebetase hydrolyzes casein, fibrinogen and fibrin, and oxidized insulin B-chain in the positions Ala14-Leu15 and Tyr16-Leu17. Its fibrinolytic activity is inhibited by EDTA and lost upon heating at 70 degrees C for 10 min. The enzyme readily hydrolyzes the A alpha-chain and more slowly the B beta-chain of fibrinogen. In fibrin, the same chains are attacked. Thus, the enzyme is an A alpha, B beta-fibrinogenase. The fibrinolytic activity of lebetase is direct, without any plasminogen activation. E280 1% is 13.0 for lebetase. The enzyme showed low hemorrhagic activity.

Amino Acid Sequence↗

PubMed1990

Comparative study of three phospholipase A2s from the venom of Vipera aspis.

1. Three phospholipase A2s, PLA2-I, PLA2-II and PLA2-III, were isolated from Vipera aspis venom by gel filtration and ion exchange chromatography. 2. Purified PLA2-I, -II and -III have mol. wts of 30,200, 16,000 and 13,500, and isoelectric points of 9.45, 7.65 and less than 4.1, respectively. 3. PLA2-I consists of an acidic subunit (mol. wt 13,700, pI: less than 3.5) and a basic subunit (mol. wt 16,500, pI: 10.6), which can be separated under highly acidic conditions. 4. PLA2-I possessed lethal activity and LD50 for this preparation was estimated to be 0.288 (0.209-0.397) micrograms/g, while lethality was not observed when PLA2-II, -III or each subunit of PLA2-I were administered. 5. Capillary permeability-increasing activity was found in the samples which possessed basic isoelectric points. Additionally, PLA2-I and its basic subunit drastically prolonged activated partial thromboplastin time of platelet rich plasma. 6. Intramuscular injections of PLA2-I, -II and -III increased serum creatine phosphokinase activity in mice, indicating that damage in muscle was caused by these enzymes. 7. NH2-terminal sequences of the three PLA2s were compared with other phospholipase A2s from snake venoms. Furthermore, antigenicities were tested using antiserum prepared against each sample.

Amino Acid Sequence↗

PubMedDate not supplied

The serotoninergic system of the brain of the viper, Vipera aspis. An immunohistochemical study.

Serotoninergic cell bodies and fibers in the brain of the viper, Vipera aspis, were visualized by immunohistochemistry. Immunoreactive cell bodies were observed in the diencephalic hypothalamic periventricular organ and in the dorsal wall of the infundibular recess, in the nuclei raphe superior and inferior of the midbrain and hindbrain, and to a lesser extent in the nuclei reticularis superior, reticularis inferior and reticularis lateralis. In contrast to other reptilian species, serotoninergic cells were also observed in the central gray matter of the midbrain in the neighbourhood of the nucleus of the trochlear nerve. Immunoreactive fibers are widely distributed throughout the brain of the viper. In the olfactory bulb, fibers were observed in the internal plexiform layer and mitral cell layer. The cerebral cortex contains the highest density of fibers in the dorsal region. The distribution of immunoreactive fibers in the dorsal ventricular ridge is extremely heterogeneous, and five subcomponents of this structure can be distinguished. The majority of diencephalic and mesencephalic structures that contain immunoreactive fibers are also primary visual centres: the nuclei geniculatus lateralis pars dorsalis, the n. posterodorsalis and n. opticus tegmenti, and the optic tectum. Serotoninergic fibers in the nuclei of the oculomotor and motor cranial nerves (III, IV, V, VII, X) are disposed in a tightly woven basket around the non-immunoreactive cell bodies of the motoneurons. These findings, together with the available literature, suggest that the serotoninergic system in snakes is comparable to that in lizards, with a massive ascending projection of fibers from the n. raphe superior to mesencephalic and prosencephalic structures, and a descending projection from the n. raphe inferior to the spinal cord.

Animals↗

PubMed2004

Factor X activator from Vipera lebetina venom is synthesized from different genes.

Vipera lebetina venom contains specific coagulant Factor X activator (VLFXA) that cleaves the Arg52-Ile53 bond in the heavy chain of human factor X. VLFXA is a glycoprotein that is composed of a heavy chain (HC) and two light chains (LC) linked by disulfide bonds. The complete amino acid sequences of the three chains of the factor X activator from V. lebetina snake venom are deduced from the nucleotide sequences of cDNAs encoding these chains. The full-length cDNA (2347 bp) sequence of the HC encodes an open reading frame (ORF) of 612 amino acids that includes signal peptide, propeptide and mature metalloproteinase with disintegrin-like and cysteine-rich domains. The light chain LC1 contains 123 and LC2 135 amino acid residues. Both light chains belong to the class of C-type lectin-like proteins. The N-termini of VLFXA chains and inner sequences of peptide fragments detected by liquid chromatography-electrospray ionization tandem mass spectrometry (LC MS/MS) from protein sequence are 100% identical to the sequences deduced from the cDNA. The molecular masses of tryptic fragments of VLFXA chains analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) also confirm the protein sequences deduced from the cDNAs. These are the first cloned factor X activator heavy and light chains. We demonstrate that the heavy and light chains are synthesized from different genes.

Amino Acid Sequence↗

PubMed2006

Isolation and characterization of an apoptotic and platelet aggregation inhibiting L-amino acid oxidase from Vipera berus berus (common viper) venom.

An L-amino acid oxidase was isolated from the venom of the common viper Vipera berus berus by a three-step procedure combining gel filtration, ion exchange and hydrophobic chromatography. The enzyme is a non-covalently bound homodimer with a monomeric molecular mass of 57.7 kDa. The N-terminal amino acid sequence and the internal peptide sequences show close structural homology with other snake venom L-amino acid oxidases. The purified protein catalyzed oxidative desamination of L-amino acids, the most specific substrate is L-Phe. The best substrates among the studied 20 amino acids were: L-Met, L-Leu, L-Phe, L-Ile, L-Arg and L-His. Five amino acids, L-Ser, L-Pro, Gly, L-Thr and L-Cys, were not oxidized. The enzyme inhibited ADP-induced platelet aggregation dose-dependently with an IC50 of 0.07 microM. The effect was neutralized by catalase. V. berus berus LAAO induced apoptosis in cultured HeLa and K562 cells as shown by DNA fragmentation gel pattern. The induction of apoptosis was inhibited by catalase.

Amino Acid Sequence↗

PubMed2005

The C-terminal and beta-wing regions of ammodytoxin A, a neurotoxic phospholipase A2 from Vipera ammodytes ammodytes, are critical for binding to factor Xa and for anticoagulant effect.

Ammodytoxin A (AtxA) from the venom of Vipera ammodytes ammodytes belongs to group IIA secreted phospholipase A2 (sPLA2), for which the major pathologic activity is presynaptic neurotoxicity. We show here that this toxin also affects hemostasis because it exhibits strong anticoagulant activity. AtxA binds directly to human coagulation factor Xa (FXa) with Kdapp of 32 nM, thus inhibiting the activity of the prothrombinase complex with an IC50 of 20 nM. To map the FXa-interaction site on AtxA, various mutants of AtxA produced by site-directed mutagenesis and expressed in Escherichia coli were tested in the study. In surface plasmon resonance (SPR) measurements, with FXa covalently attached to the sensor chip, we show that the FXa-binding site on AtxA includes several basic amino acid residues at the C-terminal and beta-wing regions of the molecule. Applying an in vitro biological test for inhibition of prothrombinase activity, we further demonstrate that the same residues are also very important for the anticoagulant activity of AtxA. We conclude that the anticoagulant site of AtxA is located in the C-terminal and beta-wing regions of this phospholipase A2. Synthetic peptides comprising residues of the deduced anticoagulant site of AtxA provide a basis to synthesize novel anticoagulant drugs.

Amino Acid Sequence↗

PubMed2005

The variability of Vipera ammodytes ammodytes venoms from Croatia--biochemical properties and biological activity.

Vipera ammodytes ammodytes venom has been used for many years in Croatia for immunization of horses and production of specific therapeutic anti-venoms. The neutralizing effectiveness of anti-venoms is directly dependent on the properties of the snake venom used for immunization. Therefore, appropriate characterization of the whole venom is necessary prior to use in the immunization procedure. In the course of such analyses, the variability in biochemical properties and biological activity was observed in venoms collected from snakes originating from different parts of Croatia. The venom pools also differed with respect to time of snake collection (1992-2003). Analyses of three samples of whole venom pools were carried out revealing differences in lethal activity (LD50), minimum haemorrhagic dose (MHD), minimum necrotizing dose (MND), phospholipase A2 activity and in anticomplementary activity. SDS-PAGE electrophoretic patterns were similar, but not identical, for all tested venom pools with respect to the number of protein bands detected, but intensity of particular components differed. Preliminary immunogenicity testing in terms of determination of specific antibodies revealed similar immunogenicity and high cross-reactivity for three samples tested.

Animals↗

PubMed2004

Characterisation of some pharmacological effects of the venom from Vipera lebetina.

Vipera lebetina is one of the most venomous snakes on the Iran plateau. Serious clinical problems such as edema, hemorrhage and tissue necrosis are observed in humans following V. lebetina envenomating. However, little information on the pharmacological properties of the venom is available. To determine haemodynamic actions of the venom of V. lebetina, the changes in the mean arterial blood pressure of anaesthetised rats following the administration of the venom were recorded. Venom (1 mg/kg, i.v.) produced rapid cardiovascular collapse, while 0.3 mg/kg (i.v.) caused only a small transient decrease in mean arterial blood pressure. Effects of the venom on perfusion pressure in the isolated rat mesenteric bed, and on contractions of the isolated rat right atrium and the isolated guinea-pig ileum, were also studied. Exposure of the isolated rat right atrium to venom (0.1-1 mg/ml) caused a transient increase followed by a sustained reduction in the amplitude and frequency of spontaneous contractions. The transient positive inotropic and chronotropic effects were abolished when the preparation was preincubated with propranolol, but not with tolazoline. N(G)-nitro-l-arginine methyl ester pretreatment attenuated the vascular hyporeactivity to phenylephrine induced by the venom in the isolated rat mesenteric vascular bed. This suggests that nitric oxide (NO) or NO-like compounds may be present in the venom and involved in its hypotensive effect. The venom (0.3-1 mg/ml) caused concentration-dependant blockade of isolated guinea-pig ileum contractions induced by electrical field stimulation, acetylcholine or KCl. This inhibitory effect of the venom was significantly reduced by prior incubation of the venom with manoalide (1 microM) indicating involvement of a phospholipase A(2) component. Further, investigation is required to identify specific toxins responsible for the above pharmacological effects.

Analysis of Variance↗

PubMed2004

Evaluation of antivenom therapy in Vipera palaestinae bites.

BACKGROUND: Vipera palaestinae antivenom has been successfully used to treat systemic and progressive local manifestations inflicted by this snake. The clinical course of several envenomations created the impression that the recommended fixed dose regimen of antivenom (50 ml) may not always be sufficient. OBJECTIVE: To evaluate the V. palaestinae antivenom fixed dose regimen and to assess the need for repeated antivenom administration as well as possible adverse effects. METHODS: Retrospective review of prospectively collected poison center data over a one-year period. RESULTS: One hundred and twelve patients were evaluated, 48% of whom were treated with antivenom. Antivenom treatment resulted in complete disappearance of systemic manifestations with no relapse. Three patients required additional doses of antivenom for marked progressive local signs--one initially received 50 ml of antivenom and two others only 30 ml. Anaphylaxis and serum sickness were each observed in 3.7% of the treated patients. CONCLUSION: The fixed dose regimen of 50 ml V. palaestinae antivenom is efficacious for the treatment of systemic and progressive local manifestations caused by this snake. There is insufficient data on whether smaller doses can be successfully used for systemic manifestations and whether initial larger doses are justified for marked progressive local signs (e.g. involvement of an entire limb). Randomized prospective controlled studies are needed to elucidate these issues.

Animals↗

PubMed2005

Histopathological changes induced by the venom of the snake Vipera raddei (Armenian adder).

The venom of the Armenian adder (Vipera raddei Boettger, 1890) was tested for its ability to induce histopathological changes in rabbits after long-term (once every 6 days for 30 days) intramuscular injection of the venom (0.35 mg/kg approx. 0.5 LD 50), by light microscopic examination of some organs (liver, heart, kidney, adrenal, lung, spleen). V. raddei (Vr) venom induces changes including necrosis and edematous appearance with cellular infiltration and vacuolation. The injury of kidneys includes significant changes of the glomerular apparatus. Lung sections showed infiltration of erythrocytes within bronchial alveoli and dilation of bronchi. Liver sections showed vascular damage, significant quantities of hemosiderin and also presence of lymphohistiocyte elements. In the heart, Armenian adder venom produced slight disruption of the structure of cardiomyocytes, fibrosis and congestion of blood vessels. The histological structure of the spleen was not disturbed by the venom but there were lymphoblasts and numerous polynuclear macrophages within the central zone of follicules, which may indicate a development of moderate inflammatory reactions and activation of the complement system. Our results suggest that the venom of V. raddei induces moderate histopathological changes in vital organs.

Adrenal Glands↗

PubMed2005

A novel metalloprotease from Vipera lebetina venom induces human endothelial cell apoptosis.

A novel endothelial cell apoptosis inducing metalloprotease (VLAIP) was found in the snake venom of Vipera lebetina. This metalloprotease is a heterodimeric glycoprotein with molecular mass of about 106 kDa. The protease hydrolyzes azocasein, fibrinogen and oxidized insulin B-chain. The enzyme readily hydrolyzes the Aalpha-chain and more slowly Bbeta-chain of fibrinogen. VLAIP does not cleave fibrin. The complete amino acid sequences of the two different monomers of VLAIP are deduced from the nucleotide sequences of cDNAs encoding these proteins. The full-length cDNA sequences of the VLAIP-A and VLAIP-B encode open reading frames of 616 and 614 amino acids that include signal peptide, propeptide and mature metalloproteinase with disintegrin-like and cysteine-rich domains. VLAIP belongs to the metalloprotease/disintegrin family of reprolysins and has high identity with the proteins that induce apoptosis of endothelial cells. Treatment of HUVEC cells with VLAIP induces changes in the attachment of cells to the substrate and causes cell death. We demonstrated that VLAIP inhibits endothelial cell adhesion to extracellular matrix proteins: fibrinogen, fibronectin, vitronectin, collagen I, and collagen IV. The induction of apoptosis by VLAIP was shown by means of a typical DNA fragmentation pattern of apoptotic cells as well as by monitoring phosphatidylserine externalization using annexin V-FITC staining and flow cytometric analysis.

Amino Acid Sequence↗

PubMed2006

L-amino acid oxidase from Vipera lebetina venom: isolation, characterization, effects on platelets and bacteria.

The L-amino acid oxidase from Vipera lebetina venom was purified to homogeneity using combination of size exclusion, ion exchange and hydrophobic chromatography. The monomeric molecular mass of the homodimeric enzyme is 60.9kDa. The N-terminal and the tryptic peptides share high homology with other snake venom L-amino acid oxidases. The enzyme displays high specificity towards hydrophobic L-amino acids, the best substrates are L-Met, L-Trp, L-Leu followed by L-His, L-Phe, L-Arg and L-Ile. Six substrates-Gly, L-Ser, L-Thr, L-Pro, L-Cys, L-Asp--were not oxidized. The enzyme has antimicrobial activity inhibiting the growth of both Gram-negative and Gram-positive bacteria. V. lebetina LAAO dose-dependently inhibited platelet aggregation induced by ADP or collagen. In case of ADP-induced aggregation the inhibitory effect was more pronounced on the second wave of aggregation.

Amino Acid Sequence↗

PubMed2006

Reproductive ecology of Vipera latastei, in the Iberian Peninsula: implications for the conservation of a Mediterranean viper.

Eurosiberian vipers have been considered model organisms, and studies on their reproductive ecology have afforded much of the current knowledge concerning viviparity in snakes. However, such studies are biased towards northern species and there is little information on Mediterranean species and/or populations. The reproductive ecology of Vipera latastei in the Iberian Peninsula was studied by analysing a large sample of specimens from collections, to better understand the conservation status of this Mediterranean viper. Males and females matured at small and similar body sizes (240 and 265 mm snout-vent length, respectively) and reproductive cycles in both sexes were seasonal. Spermatogenesis peaked in August, vitellogenesis developed in spring and the timing of the mating period was puzzling, with populations mating in autumn, spring, or in both seasons. The most striking finding was that adult females reproduced triennially on average. Lataste's viper is currently in continuous decline in the IP, and most of its populations are isolated in Mediterranean mountains. We hypothesize that prey scarcity and the brevity of the activity period in mountain habitats diminishes the ability of vipers to recover over the short term the energy expended in reproduction. The species needs 2 years for the acquisition and storage of energy ("capital breeder"), and a third year for the expenditure of this energy (in vitellogenesis and embryogenesis), a year during which females feed consistently ("income breeder"). Thus, this viper combines both strategies to supply the reproductive energy cost. Current decline in population and distribution, together with a poor capacity to renew populations, renders Lataste's viper vulnerable to environmental stochasticity.

Animals↗

PubMed1988

Biological study of muscle degenerating hemorrhagic factor from the venom of Vipera aspis aspis (aspic viper).

1. A hemorrhagic factor was isolated from Vipera a. aspis venom by gel filtration, ion-exchange chromatography and affinity chromatography. 2. Molecular weight of the purified factor was determined to be 67,000 Da, which was composed of 552 amino acid residues. 3. The minimum hemorrhagic dose (MHD) was measured to be 0.11 micrograms per mouse with subcutaneous injection. The hemorrhagic activity was inhibited by chelating agents and reductant. 4. The hemorrhagic factor possesses proteolytic activity against dimethylcasein. 5. Serum creatine phosphokinase level was rapidly increased within 30 min following injections of this preparation into the mice thighs. 6. Actin, one of the main components of muscle fiber, is apparently digested by the hemorrhagic factor. The pathological findings are further reported in this paper.

Amino Acids↗

PubMed2002

Biochemical characterization of fibrinogenolytic serine proteinases from Vipera lebetina snake venom.

Two glycosylated serine fibrinogenases isolated from Vipera lebetina venom have homologous N-terminal sequences and antigenic determinants but can be clearly differentiated according to substrate specificity, glycosylation levels, molecular mass and fibrinogen degradation. alpha-Fibrinogenase has no homolog among known serine proteinases. It has N-terminal similarity with snake venom arginine esterases but does not hydrolyze the esters of arginine, lysine and tyrosine. The enzyme has strong proteolytic activity and degrades alpha-chain of fibrinogen altering its clottability by thrombin. beta-Fibrinogenase is a typical arginine esterase which hydrolyzes esters and amides of arginine and attacks the beta-chain of fibrinogen.

Amino Acid Sequence↗

PubMed2002

Purification and characterisation of two hemorrhagic metalloproteinases from the venom of the long-nosed viper, Vipera ammodytes ammodytes.

Two hemorrhagic proteins, VaH1 and VaH2, have been purified from Vipera ammodytes ammodytes venom. They are monomeric glycoproteins of an apparent molecular mass of 70kDa and multiple isoelectric points around pH 5.5. Both molecules are proteolytically active against azocasein as substrate. VaH1, which was characterised in detail, showed maximum activity at pH 7.5. Ethylenediaminetetraacetic acid eliminated the proteolytic as well as the hemorrhagic activity of VaH1 while iodoacetamide, phenylmethylsulfonyl fluoride and pepstatin A, inhibitors of cysteine, serine and aspartic proteinases respectively, had no effect. VaH1 is therefore a metalloproteinase whose hemorrhagic activity is very likely the result of its proteolytic activity. VaH1 is a fibrinogenase, hydrolysing exclusively the Aalpha-chain of fibrinogen. In the B-chain of insulin it cleaved with a high preference the bond between Ala(14) and Leu(15). Based on its molecular mass, VaH1 (as well as VaH2) is a Class P-III metalloproteinase. Partial amino acid sequences of its CNBr fragments demonstrated a high level of identity with the reprolysin subfamily of zinc-metalloproteinases.

Amino Acid Sequence↗