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PubMed1989

Immunological relationships of phospholipase A2 neurotoxins from snake venoms.

Polyclonal rabbit antisera were raised against ten snake phospholipase A2 neurotoxins and one snake phospholipase A2 cytotoxin. Immunological cross-reactivities between these toxins, two other snake phospholipase A2 enzymes and pancreatic phospholipase A2 were studied using ELISA technology. All snake phospholipase A2 neurotoxins fell into two main antigenic classes. One antigenic class was composed of all the elapid toxins tested (textilotoxin, taipoxin, notexin, pseudexin and beta-bungarotoxin), the cytotoxic phospholipase A2 from Naja naja atra and pancreatic phospholipase A2. beta-Bungarotoxin seemed to be in an immunological subclass of its own compared to the rest of the elapid toxins. The second antigenic class was comprised of crotalid and viperid phospholipase A2 neurotoxins (crotoxin, concolor toxin, Mojave toxin, vegrandis toxin, ammodytoxin and caudoxin). Our data indicated that the viperid toxins, caudoxin and ammodytoxin, were an immunological subclass apart from the crotalid toxins.

Animals↗
PubMed1990

Lack of the blocking effect of cobrotoxin from Naja naja atra venom on neuromuscular transmission in isolated nerve muscle preparations from poisonous and non-poisonous snakes.

Neuromuscular transmission in the Chinese cobra Naja naja atra was not affected by its own toxin (cobrotoxin) at a concentration of as high as 100 microM, while in the frog a concentration of less than 0.1 microM cobrotoxin depressed the amplitude of the end-plate potential to less than 10% of its original value within 30 min or directly blocked the nerve-evoked muscle action potential. The lack of effect of cobrotoxin was also observed in the nerve-muscle preparations from a pit viper (Agkistrodon blomhoffii brevicaudus) and three species of non-poisonous snakes (Elaphe dione, Elaphe bimaculata and Elaphe rufodorsata). On the other hand, the snake preparations were sensitive to the blocking effect of D-tubocurarine and less sensitive to that of atropine, indicating that the nicotinic acetylcholine receptor is responsible for transmission between the nerve and the skeletal muscle of the snake. We suggest that the snake nicotinic cholinergic receptor lacks the cobrotoxin binding-site.

Action Potentials↗
PubMed1990

Inhibition of phosphorylation of rat synaptosomal proteins by snake venom phospholipase A2 neurotoxins (beta-bungarotoxin, notexin) and enzymes (Naja naja atra, Naja nigricollis).

Some snake venom neurotoxins, such as beta-bungarotoxin (beta-BuTX) and notexin, which inhibit the release of neurotransmitter at both peripheral and central presynaptic terminals possess phospholipase A2 activity. In contrast, most snake venom phospholipase A2 enzymes such as those isolated from Naja naja atra and Naja nigricollis are structurally homologous to these neutrotoxins but do not have any specific or potent presynaptic action although they have higher enzymatic activities than the neurotoxins. In order to investigate the mechanisms of presynaptic action of the snake venom neurotoxins, we studied their effects on phosphorylation of rat brain synaptosomal proteins. It is known that phosphorylation of synapsin I, a neuron specific and synaptic vesicle associated phosphoprotein, increases neurotransmitter release. Incubation of cerebral cortical synaptosomes with 32P-orthophosphate at 37 degrees C for 30 min, caused significant phosphorylation of a wide mol. wt range of proteins including most markedly those proteins in the mol. wt range (81,000-86,000) of synapsin I. Both snake venom phospholipase A2 neurotoxins and enzymes (5, 15 and 50 nM) inhibited phosphorylation in a Ca2(+)-dependent manner with the following order of potencies: beta-BuTX greater than N.n. atra phospholipase A2 greater than or equal to notexin greater than N. nigricollis phospholipase A2. Five nanomoles of beta-BuTX, which has the lowest phospholipase A2 activity, inhibited phosphorylation of a wide range of mol. wt proteins (51,000-188,000) by 42-58%. At the same concentration, N.n. atra phospholipase A2 (which possesses the highest enzymatic activity), notexin and N. nigricollis phospholipase A2 caused less inhibition than beta-BuTX, ranging from 0-40% depending on the agent used. These results indicate that there is no correlation between their potencies in inhibiting phosphorylation and the levels of their phospholipase A2 activities. An inhibitory activity on phosphorylation may be at least partially responsible for a presynaptically-induced block of neurotransmitter release.

Animals↗
PubMed1993

Acetylcholine receptor binding characteristics of snake and cone snail venom postsynaptic neurotoxins: further studies with a non-radioactive assay.

The binding of postsynaptic neurotoxins from snake and marine cone snail (Conus sp.) venoms to nicotinic acetylcholine receptor (AchR) was investigated with an ELISA-based, non-radioactive assay. Three snake postsynaptic toxins from the long-chain group (Naja naja kaouthia cobratoxin, Naja oxiana neurotoxin I, Bungarus multicinctus alpha-bungarotoxin) and short-chain group (Naja naja atra cobrotoxin, Naja oxiana neurotoxin II, and Laticauda semifasciata erabutoxin b) were studied. Both types of snake postsynaptic toxins showed a dose-response with constant AchR (50 micrograms/ml) and varying toxin concentrations (50-0.035 micrograms/ml). The minimum detection limits of the assay for snake toxins ranged from 310 to 1240 ng/ml (40-160 pmole/ml), depending on the toxin. Unlike any of the short-chain toxins, long-chain toxins consistently bound less receptor and reached maximum absorbance levels with toxin concentrations of 10-50 micrograms/ml. Competition for AchR binding between cone snail postsynaptic neurotoxins (conotoxins GI, MI, SI) and alpha-bungarotoxin or cobrotoxin resulted in a dose-response. The postsynaptic conotoxins were uniformly better competitors for AchR binding with alpha-bungarotoxin than with cobrotoxin. Heat stability studies with neurotoxin I, erabutoxin b, or cobrotoxin revealed a loss in AchR binding activity with increasing temperature. alpha-Bungarotoxin heated at 90 degrees C had increased AchR binding activity by 105%, relative to 25 degrees C samples, but lost the majority of its binding activity after 100 degrees C. The enhanced binding of heated alpha-bungarotoxin to AchR was specific, as evidenced by a competitive dose-response with unheated alpha-bungarotoxin, but heated toxin lacked any biological activity in the mouse lethal assay. When conotoxins GI or MI were heated at 100 degrees C, there was no detectable loss in AchR binding activity, and only a slight decrease in mouse lethality.

Animals↗
PubMed1989

A Golgi study on the accessory olfactory bulb in the snake, Elaphe quadrivirgata.

The intrinsic organization of the accessory olfactory bulb (AOB) in the snake was studied using the rapid Golgi method. A distinct laminar organization was observed in the snake AOB. Beginning with the most superficial surface, the following layers were distinguished: the layer of the vomeronasal fibers, the olfactory glomeruli, the mitral cells, the deep fiber plexus, the granule cells and the ependymal cells. While the general organizational pattern of the snake AOB resembles that of the main olfactory bulb (MOB) and the AOB reported in various vertebrate species, the present study shows that: (1) the external and internal plexiform layers cannot be identified as independent layers and are considered to be included in the mitral cell layer; (2) the afferent and efferent paths, which are disseminated in the granule cell layer in the mammalian MOB, accumulate external to the granule cell layer to form the layer of the deep fiber plexus: and (3) as a result of accumulation of the afferent and efferent paths in the layer of the deep fiber plexus, the granule cell layer is very fiber-sparse. These structural patterns are quite similar to those of the snake MOB.

Animals↗
PubMed1991

Haematology of the grass snake Natrix natrix natrix L.

1. Haematological parameters and cytomorphological picture of circulating blood of the grass snake Natrix natrix natrix L. were studied. Mean annual values of the haemoglobin concentration, haematocrit level, red cell counts, erythrocytes indices, erythrocyte sedimentation rate, thrombocyte and leucocyte counts, per cent composition of white blood cells and size of morphotic elements were determined for a population sample (N = 154) of the species, considering the sex of snakes. 2. Parameters of red blood cell system (RCC, Hb, Hct) were statistically significantly higher in males, remaining indices showed no statistically significant differences. 3. A strict positive correlation was found between RCC, Hb and Hct in the studied sample. 4. Cytomorphology of blood is presented in microphotographs. 5. In the discussion haematological data for the grass snake and other snakes are compared.

Animals↗
PubMed1978

Fingerprint correspondence of hemoglobins and the relationships of sea snakes.

1. Peptide fingerprints of tryptic digests of the globins of sea snake species of Hydrophis, Pelamis, Aipysurus, Laticauda and the terrestrial elapid Naja were compared. 2. Globin divergence, as estimated from peptide fingerprints, paralleled closely transferrin divergence, as measured immunologically. 3. Taxonomic affinities, suggested by the fingerprint data, are concordant with McDowell's taxonomic system for sea snakes with the following exceptions: (a) Laticauda shows a closer affinity to the true sea snakes than to the terrestrial elapid Naja. (b) Sea snakes appear to be more widely divergent from terrestrial elapids than his scheme suggests.

Animals↗
PubMed1982

Hepatic cytochrome P-450-dependent monooxygenase systems of the trout, frog and snake--II. Monooxygenase activities.

1. Activities of hepatic monooxygenase systems (aminopyrine N-demethylase, benzo[a]pyrene hydroxylase and p-nitrophenetole O-deethylase) of the brown trout (Salmo trutta), leopard frog (Rana pipiens) and garter snake (Thamnophis) were observed to be considerably lower than those of the rat. The specific activities of their P-450 cytochromes relative to rates of product formation were also much lower than those of the rat, except benzo[a]pyrene hydroxylation by frog microsomes, in which case, the value was about the same as that for the rat. 2. The monooxygenase systems of the trout, frog and snake were identified as cytochrome P-450 systems by the inhibitory effects of carbon monoxide, SKF 535-A, alpha-naphthoflavone and by the requirement for NADPH. 3. NADH synergism of NADPH-supported monooxygenase activities of hepatic microsomes of the trout, frog and snake suggest the participation of cytochrome b5 in these reactions. For the trout, p-nitrophenetole metabolism was supported almost as well by NADH as by NADPH, which suggests that in this species, cytochrome b5 may play an important role in certain monooxygenase reactions. 4. Qualitative differences in the P-450 cytochromes of the trout, frog, snake and rat were indicated by differences in the inhibitory effects of SKF 525-A and alpha-naphthoflavone on monooxygenase activities.

Aminopyrine N-Demethylase↗
PubMed2006

Isolation and characterization of rufoxin, a novel protein exhibiting neurotoxicity from venom of the psammophiine, Rhamphiophis oxyrhynchus (Rufous beaked snake).

Colubrid snake venoms potentially represent a vast source of novel biological actives and structural motifs owing to their diverse phylogeny. The present study describes the identification of rufoxin, a neurotoxin from the venom of Rhamphiophis oxyrhynchus (Rufous beaked snake) which is a member of the African colubrid lineage, the psammophiines. Rufoxin (1 microM) displayed reversible post-synaptic neurotoxic activity as evidenced by significant inhibition of indirect twitches and responses to exogenous nicotinic agonists in the chick biventer cervicis nerve-muscle preparation. Rufoxin (0.1-1.0 microM) also caused a rightward parallel shift of cumulative concentration-response curves to carbachol (CCh; 0.6-80 microM) without a significant depression of the maximum response, suggestive of classical competitive antagonism at the skeletal muscle nicotinic receptor. Rufoxin lacks NH(2)-terminal sequence homology to previously identified snake venom toxins. This work indicates a wider distribution of neurotoxins across the advanced snake superfamily than previously described.

Analysis of Variance↗
PubMed2006

Snake venom glutaminyl cyclase.

Glutaminyl cyclase (QC) catalyzes N-terminal glutamine cyclization of many endocrine peptides and is typically abundant in brain tissue. As three-finger toxins in the venoms of colubrid snakes Boiga dendrophila and Boiga irregularis contain N-terminal pyroglutamate, we searched for QC in venom glands of both snakes. Here we report cDNA sequences of QC from brain and venom gland tissues of Boiga species. We propose that QC expressed in snake venom gland tissue plays a role in the N-terminal pyroglutamate formation of several snake venom toxins, indirectly contributing to venom potency.

Amino Acid Sequence↗
PubMed2004

Protocol and monitoring to improve snake bite outcomes in rural Ghana.

A study was conducted in Mathias Hospital, Yeji, an area of Ghana, where snake bite cases are an important cause of morbidity and mortality, with a case fatality rate of 11% (8/72). Case management difficulties included uncertainty about the assessment of the severity of envenoming, the dosage of antivenom, and the response to treatment. An intervention with several components was introduced: development of a treatment protocol, staff training, monitoring of compliance and patient education. During a 33-month post-intervention period there was excellent protocol compliance, fewer snake bite complications, and a fall in mortality rate to 1.3% (3/238) compared with a 15-month baseline review. There was a 50% increase in snake bite admissions and fewer delays. To improve snake bite outcomes in comparable settings, particularly if inexperienced staff are involved in care, we recommend a similar quality assurance project, involving case review and use of a treatment protocol with monitoring of compliance to sustain an improved approach.

Adult↗
PubMedDate not supplied

Snake bites in Kenya: a preliminary survey of four areas.

Primary data were collected on the incidence, severity and species responsible for snake bites in 4 areas of Kenya: (i) Kakamega and western Kenya, (ii) Lake Baringo and Laikipia, (iii) Kilifi and Malindi, and (iv) northern Kenya. The overall average frequency of snake bite was 13.8 per 100,000 population per year (range 1.9-67.9). The minimum rate of snake bite mortality was 0.45/100,000/year. Thirty-four of the 50 units visited reported no knowledge of death from snake bite in the last 5 years. Possible reasons for the low estimates are discussed. Traditional treatments were common, especially the use of herbal remedies and incisions at the wound site.

Antivenins↗
PubMed2000

The envenomation syndrome caused by the Australian Red-bellied Black Snake Pseudechis porphyriacus.

The Australian elapids inject venom which is characteristic of each species; and which cause characteristic and specific envenomation syndromes in human victims of snakebite. Because many of the medically significant Australian elapids look similar, when glimpsed in the field by snakebite victims, defining human envenomation syndromes with secure species identification has been a slow process. Correlations between securely identified species and the human envenomation syndromes which they produce are still evolving. The genus Pseudechis is the most widespread in Australia of the dangerous Australian elapid genera; and P. porphyriacus, the Red-bellied Black Snake, was the first terrestrial Australian elapid to be described and illustrated and the first to be the subject of experimental study. We present here five previously unreported cases of human envenomation in which the species diagnosis is secure. From these and with the perspective of a selected literature review, we describe the full envenomation syndrome of this species. Until the development of the Commonwealth Serum Laboratories' Venom Detection Kit in 1979 and the occasional case report of victims of securely identified species, envenomation syndromes for most Australian snake species have remained indeterminate, because of the lack of professional expertise in the identification of the species involved. Symptoms of the P. porphyriacus envenomation syndrome include those of bite-site pain, nausea and vomiting, generalised pruritus, chest pain, prostration and abnormalities of taste and smell. Signs include local necrosis and scarring of tissue at the bite-site, gross inflammation of surrounding tissues and, at least in one case, epilepsy. Although envenomation by the Red-bellied Black Snake is not lethal in adults, the correct therapy is Tiger Snake antivenom, administered with judgement, taking into account knowledge of the specific envenomation syndrome of this species and the clinical status of the victim.

Adolescent↗
PubMed2001

Novel in vitro assays for assessing the haemorrhagic activity of snake venoms and for demonstration of venom metalloproteinase inhibitors.

Standard methods used for assessing the haemorrhagic toxicity of snake venoms and the effectiveness of antivenoms are laborious, expensive and involve the use of large numbers of laboratory animals. This paper examined the feasibility of using a gelatin degradation ELISA for preliminary screening of snake venom metalloproteinases (MPs). Potent gelatinolytic activity was observed in venoms from snakes of the family Viperidae and, as expected, little or no activity was evident in the venoms of snakes that induce neurotoxic pathology (most elapids). A reverse gelatin zymography assay was used on a variety of venoms to demonstrate a number of inhibitors of MP activity, the first such demonstration of its kind.

Electrophoresis, Polyacrylamide Gel↗
PubMed1997

Synopsis of recent developments in venomous snake systematics.

Changes to our understanding of venomous snake systematics, and the consequent changes in the nomenclature of these animals, have traditionally been a great source of confusion among biomedical researchers. This paper aims to facilitate access to the taxonomic literature by presenting a synopsis of the changes in venomous snake systematics that have taken place recently (primarily since 1992), together with some comments on the implications of these changes for toxinologists and clinicians. Some long-standing problems in venomous snake taxonomy receive special attention. This includes Asiatic Naja, Asiatic Agkistrodon/Gloydius, Bothrops and related genera, Trimeresurus, Echis, Daboia (including Daboia russellii) and Vipera. It is hoped that this synopsis will result in the use of a more up-to-date and interpretable nomenclature for venomous snakes in the toxinological literature.

Animals↗
PubMed1998

Snake venoms and the hemostatic system.

Snake venoms are complex mixtures containing many different biologically active proteins and peptides. A number of these proteins interact with components of the human hemostatic system. This review is focused on those venom constituents which affect the blood coagulation pathway, endothelial cells, and platelets. Only highly purified and well characterized snake venom proteins will be discussed in this review. Hemostatically active components are distributed widely in the venom of many different snake species, particularly from pit viper, viper and elapid venoms. The venom components can be grouped into a number of different categories depending on their hemostatic action. The following groups are discussed in this review: (i) enzymes that clot fibrinogen; (ii) enzymes that degrade fibrin(ogen); (iii) plasminogen activators; (iv) prothrombin activators; (v) factor V activators; (vi) factor X activators; (vii) anticoagulant activities including inhibitors of prothrombinase complex formation, inhibitors of thrombin, phospholipases, and protein C activators; (viii) enzymes with hemorrhagic activity; (ix) enzymes that degrade plasma serine proteinase inhibitors; (x) platelet aggregation inducers including direct acting enzymes, direct acting non-enzymatic components, and agents that require a cofactor; (xi) platelet aggregation inhibitors including: alpha-fibrinogenases, 5'-nucleotidases, phospholipases, and disintegrins. Although many snake venoms contain a number of hemostatically active components, it is safe to say that no single venom contains all the hemostatically active components described here. Several venom enzymes have been used clinically as anticoagulants and other venom components are being used in pre-clinical research to examine their possible therapeutic potential. The disintegrins are an interesting group of peptides that contain a cell adhesion recognition motif, Arg-Gly-Asp (RGD), in the carboxy-terminal half of their amino acid sequence. These agents act as fibrinogen receptor (integrin GPIIb/IIIa) antagonists. Since this integrin is believed to serve as the final common pathway leading to the formation of platelet-platelet bridges and platelet aggregation, blockage of this integrin leads to inhibition of platelet aggregation regardless of the stimulating agent. Clinical trials suggest that platelet GPIIb/IIIa blockade is an effective therapy for the thrombotic events and restenosis frequently accompanying cardiovascular and cerebrovascular disease. Therefore, because of their clinical poten tial, a large number of disintegrins have been isolated and characterized.

Amino Acid Sequence↗
PubMed1992

Natural cytotoxic cell activity in the snake Psammophis sibilans.

Thymocytes, splenocytes and peripheral blood mononuclear cells (PBMC) of the snake Psammophis sibilans consistently killed the human erythroleukemic cells K562 in a 4 h assay as judged by lactate dehydrogenase enzyme release. PBMC and splenocyte natural cytotoxicity (NC) increased proportionally with increase in the effector/target cell ratio. Spontaneous killer cell activity was consistently 2-3 times higher in peripheral blood (PB) than in spleen. On the other hand, thymocytes displayed low, yet detectable, NC. In an attempt to define the cell subpopulation responsible for natural killer (NK) activity, PBMC were depleted of macrophages or B lymphocytes before use in NK cell assays against K562 cells. Depletion of macrophages did not impair NK activity thus suggesting that macrophages do not mediate spontaneous lysis in the present 4 h assay. Conversely, removal of B lymphocytes by panning onto dishes coated with monoclonal antibody against snake Ig significantly reduced, but did not eliminate, PBMC spontaneous cytotoxicity. These data suggest that T, B and perhaps distinct NK cells participate in spontaneous lysis. This suggestion was confirmed by studies of NC in thymus, spleen and PB the year round. Strong NC was detected during spring and autumn when high numbers of leukocytes including T and B cells can be recovered from spleen and PB. Negligible spontaneous cytotoxicity was observed during early and mid-summer and in winter, periods of the year when snakes are thymus-less and contain few T and B cells in peripheral lymphoid organs. These findings, the first to document natural cytotoxic activity in snakes, were discussed in relation to the issue of NK cell identity in vertebrates.

Animals↗
PubMed1993

Exotic pet medicine I. Snakes.

Of the 6,000 extant species of reptiles, approximately 2500 are snakes. Several dozen species of snakes have become popular in the pet trade, and to meet the increased demand, more and more species are being bred in captivity. Along with this popularity comes the need for more sound veterinary expertise. Although much biomedical information on snakes exists in the literature and can be found in texts on reptile medicine, few reviews have tried to consolidate the literature on this subject. The purpose of this article is to bring together information on the most pertinent aspects of snake medicine and disease.

Animal Husbandry↗