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At least 19 recordsLinked to original sources
PubMed2002

Effect of snake venom procoagulants on snake plasma: implications for the coagulation cascade of snakes.

Several snake venoms contain proteinases that activate zymogens in the coagulation cascade and thus exhibit their procoagulant effects. While most procoagulant proteinases from snake venoms are dissimilar to coagulation factors, Group D (trocarin, notecarin) and C (pseutarin) prothrombin activators are structural and functional homologues of factor Xa and the prothrombinase complex, respectively. We examined the effect of these and other procoagulants from snake venoms as well as mammalian and snake thromboplastins on the coagulation of plasmas of Notechis scutatus, Pseudonaja textilis (both procoagulant venoms), Python reticulatus (non-venomous) and Crotalus atrox (non-procoagulant venom) snakes. The results indicate that the intrinsic pathway seems to be weak or absent only in venomous snakes, while the extrinsic pathway is fully functional in all snakes. Python and Crotalus plasmas have extrinsic pathways similar to that in mammals. In contrast, although Notechis and Pseudonaja plasmas were clotted by a Group C activator, they failed to clot upon the addition of factor Xa and Group D activators. The mechanism of this resistance is still elusive.

Animals↗
PubMed2004

High-dose anti-snake venom versus low-dose anti-snake venom in the treatment of poisonous snake bites--a critical study.

OBJECTIVES: To asses the optimum dose of anti-snake venom to treat snake bites cases effectively. This is particulary relevant in the present scenario when the cost of anti-snake venom ( Serum Institute of India) has gone up to nearly Rs. 400 per vial and the cross-section of people usually affected belong to the poor socioeconomic class. METHODOLOGY: One hundred snake bite cases with envenomation, irrespective of whether they were bitten by viper, cobra or krait, brought within 24 hours of the bite to Jubilee Mission Hospital, Trichur, Kerala State during the 15 months from August 2001 to October 2002 were randomized into two groups of 50 cases each, irrespective of the severity of the cases. One group received a fixed dose regime of six vials of anti-snake venom and the other 12 vials of the same. RESULTS: In the low-dose group there were five deaths giving a mortality rate of 10%, nine (18%) required dialysis and three (6%) required ventilatory support. In the high-dose group there were seven deaths giving a mortality rate of 14%, 13 (26%) required dialysis and three (6%) required ventilatory support. The average hospital stay for the low-dose group was 8.42 days while that of the high-dose group was 9.02 days. CONCLUSION: While there was no additional advantage in following a high-dose regime for snake bite cases, there was considerable financial gain by following the low-dose regime, Most of the parameters showed a beneficial trend for the low-dose group though the differences were not statistically significant.

Adolescent↗
PubMed1988

Muscular mechanisms of snake locomotion: an electromyographic study of lateral undulation of the Florida banded water snake (Nerodia fasciata) and the yellow rat snake (Elaphe obsoleta).

Electromyography and cinematography were used to determine the activity of epaxial muscles of colubrid snakes during terrestrial and aquatic lateral undulatory locomotion. In both types of lateral undulation, at a given longitudinal position, segments of three muscles (Mm. semispinalis-spinalis, longissimus dorsi, and iliocostalis) usually show synchronous activity. Muscle activity propagates posteriorly and generally is unilateral. With each muscle, large numbers of adjacent segments (30 to 100) show simultaneous activity. Terrestrial and aquatic undulation differ in two major respects. (1) During terrestrial undulation, muscle activity in a particular region begins when that portion of the body has reached maximal convex flexion and ends when it is maximally concave; this phase relation is uniform along the entire snake. During swimming, however, muscle activity passes posteriorly faster than the wave of vertebral flexion, causing the relation of muscle activity to flexion to change along the length of the snake. (2) In the terrestrial mode, the block of active muscle segments remains approximately constant in size as it passes down the snake, whereas during swimming the number of adjacent active muscle segments increases posteriorly. Despite the fact that Elaphe obsoleta has nearly twice as many body vertebrate as Nerodia fasciata (240 vs. 125), the only difference observed in the swimming of these two species is that a larger number of adjacent muscle segments is simultaneously active in comparable regions of Elaphe obsoleta than in Nerodia fasciata.

Analysis of Variance↗
PubMed2003

Australian tiger snake (Notechis scutatus) and mexican coral snake (Micruris species) antivenoms prevent death from United States coral snake (Micrurus fulvius fulvius) venom in a mouse model.

BACKGROUND: Wyeth-Ayerst has discontinued production of Antivenin (Micrurus fulvius). Currently, there is no other approved coral snake antivenom available in the United States. METHODS: This study was a randomized, placebo-controlled and blinded determination of the ability of a Mexican Micrurus (coral snake) antivenom and an Australian Notechis (tiger snake) antivenom to prevent lethality from a United States Micrurus fulvius fulvius venom in a mouse model. Venom dosing was based on an LD50 determined for this experiment. Our comparison groups included: (1) M. f. fulvius venom + Micrurus antivenom, (2) M. f. fulvius venom + Notechis antivenom, (3) M. f. fulvius venom + protein control, (4) 0.9% normal saline + protein control, (5) saline + Notechis antivenom, (6) saline + Micrurus antivenom. Venom dose was 5 times the determined LD50. The antivenom amounts were capable of neutralizing 10 times the venom injected (50 times the LD50). RESULTS: The LD50 of M. f. fulvius venom was determined to be 0.85 mg/kg. All mice in both antivenom test groups were protected from lethality for the entire 24-hour observation period. Six of the 7 mice in the venom test group died, with a survival time of 349 +/- 382 minutes (mean +/- s.d.) after the venom injection. All three groups of control mice survived the entire 24-hour observation period. CONCLUSIONS: Mexican Micrurus antivenom and Australian Notechis antivenom provide protection from lethality in mice envenomated with a United States M. f. filvius venom.

Animals↗
PubMed2003

Snake bioacoustics: toward a richer understanding of the behavioral ecology of snakes.

Snakes are frequently described in both popular and technical literature as either deaf or able to perceive only groundborne vibrations. Physiological studies have shown that snakes are actually most sensitive to airborne vibrations. Snakes are able to detect both airborne and groundborne vibrations using their body surface (termed somatic hearing) as well as from their inner ears. The central auditory pathways for these two modes of "hearing" remain unknown. Recent experimental evidence has shown that snakes can respond behaviorally to both airborne and groundborne vibrations. The ability of snakes to contextualize the sounds and respond with consistent predatory or defensive behaviors suggests that auditory stimuli may play a larger role in the behavioral ecology of snakes than was previously realized. Snakes produce sounds in a variety of ways, and there appear to be multiple acoustic Batesian mimicry complexes among snakes. Analyses of the proclivity for sound production and the acoustics of the sounds produced within a habitat or phylogeny specific context may provide insights into the behavioral ecology of snakes. The relatively low information content in the sounds produced by snakes suggests that these sounds are not suitable for intraspecific communication. Nevertheless, given the diversity of habitats in which snakes are found, and their dual auditory pathways, some form of intraspecific acoustic communication may exist in some species.

Acoustics↗
PubMed2001

Bumpus in the snake den: effects of sex, size, and body condition on mortality of red-sided garter snakes.

Huge breeding aggregations of red-sided garter snakes (Thamnophis sirtalis parietalis) at overwintering dens in Manitoba provide a unique opportunity to identify sources of mortality and to clarify factors that influence a snake's vulnerability to these factors. Comparisons of sexes, body sizes, and body condition of more than 1000 dead snakes versus live animals sampled at the same time reveal significant biases. Three primary sources of mortality were identified. Predation by crows, Corvus brachyrhynchos (590 snakes killed), was focussed mostly on small snakes of both sexes. Crows generally removed the snake's liver and left the carcass, but very small snakes were sometimes brought back to the nest. Suffocation beneath massive piles of other snakes within the den (301 dead animals) involved mostly small males and (to a lesser extent) large females; snakes in poor body condition were particularly vulnerable. Many emaciated snakes (n = 142, mostly females) also died without overt injuries, probably due to depleted energy reserves. These biases in vulnerability are readily interpretable from information on behavioral ecology of the snakes. For example, sex biases in mortality reflect differences in postemergence behavior and locomotor capacity, the greater attractiveness of larger females to males, and the high energy costs of reproduction for females.

Animals↗
PubMed2000

Chlorinated hydrocarbon concentrations in plasma of the Lake Erie water snake (Nerodia sipedon insularum) and northern water snake (Nerodia sipedon sipedon) from the Great Lakes basin in 1998.

From the Great Lakes basin, concentrations of 59 congener-specific polychlorinated biphenyls (PCBs) and 14 organochlorine pesticides were measured in blood plasma of northern water snake (Nerodia sipedon sipedon) and Lake Erie water snake (Nerodia sipedon insularum), which is endangered in Canada. In 1998, four male adult Lake Erie water snakes were sampled from Pelee Island, western Lake Erie; four male northern water snakes were sampled at Little Lake, about 20 km north of Parry Sound in central Ontario; and four adult gravid female northern water snakes were sampled from Garden Island, eastern Lake Ontario. The blood plasma was pooled by site for a total of three samples analyzed. The Pelee Island sample from male Lake Erie water snakes contained less than half the lipid concentration (0.349%) than samples from the other sites, but it was the most contaminated with PCBs, even on a wet weight basis. Summed concentration of individual PCBs in the Pelee Island sample was 167 ng/g (wet weight), which was 14-fold higher than the next most contaminated sample, which was from Little Lake. The plasma sample from Little Lake contained 12 ng/g (WW) and was four times more contaminated with PCBs than the sample from female snakes from Garden Island, Lake Ontario. Organochlorine pesticide concentrations in plasma were relatively similar among sites. None of the pesticides was found above trace concentrations (0.1-0.9 ng/g) except pp'-DDE, which occurred at 2-5 ng/g among sites. PCB congener patterns in the Lake Erie water snakes were compared to PCB patterns in plasma of common snapping turtle (Chelydra serpentina serpentina) from Lake Ontario, herring gull eggs (Larus argentatus) from western Lake Erie, and mudpuppy eggs (Necturus maculosus) from the Detroit River. The PCB patterns in water snake and herring gull sample were most similar, followed by the pattern in snapping turtle plasma. The presence of more lower-chlorinated chlorobiphenyls in the mudpuppy eggs relative to the other species made this sample distinct from the water snake, gull, and turtle.

Animals↗
PubMed2004

Preattentive bias for snake words in snake phobia?

Stroop interference and skin conductance responses (SCRs) for words related to snakes, spiders, flowers, and mushrooms were studied in a group of women (n=40) with snake phobia who were randomised to a stress or no-stress condition. The 21 low-stress snake phobics showed Stroop interference for unmasked (but not for masked) snake words, compared with 21 age- and sex-matched controls. Stroop interference was not significantly different between high-stress and low-stress snake phobics. No support for stronger SCRs for masked snake words was found in snake phobics in a lexical decision task with masked presentations of the same words. The lack of a masked Stroop interference in snake phobics suggests a possible difference in cognitive-emotional mechanisms underlying specific phobia vs. other anxiety disorders that deserves further investigation.

Adult↗
PubMed2005

Putting the brakes on snake venom evolution: the unique molecular evolutionary patterns of Aipysurus eydouxii (Marbled sea snake) phospholipase A2 toxins.

Accelerated evolution of toxins is a unique feature of venoms, with the toxins evolving via the birth-and-death mode of molecular evolution. The venoms of sea snakes, however, are remarkably simple in comparison to those of land snakes, which contain highly complex venoms. Aipysurus eydouxii (Marbled sea snake) is a particularly unique sea snake, feeding exclusively upon fish eggs. Secondary to this ecological change, the fangs have been lost and the venom glands greatly atrophied. We recently showed that the only neurotoxin (a three-finger toxin) gene found in the sea snake A. eydouxii has a dinucleotide deletion, resulting in the loss of neurotoxic activity. During these studies, we isolated and identified a number of cDNA clones encoding isozymes of phospholipase A(2) (PLA(2)) toxins from its venom gland. Sixteen unique PLA(2) clones were sequenced from the cDNA library and TA cloning of reverse transcription-polymerase chain reaction products. Phylogenetic analysis of these clones revealed that less diversification of the PLA(2) toxins has occurred in the A. eydouxii venom gland in comparison to equivalent terrestrial and other marine snakes. As there is no longer a positive selection pressure acting upon the venom, mutations have accumulated in the toxin-coding regions that would have otherwise had a deleterious effect upon the ability to use the venom for prey capture. Such mutations include substitutions of highly conserved residues; in one clone, the active site His(48) is replaced by Arg, and in two other clones, highly conserved cysteine residues are replaced. These mutations significantly affect the functional and structural properties of these PLA(2) enzymes, respectively. Thus, in A. eydouxii, the loss of the main neurotoxin is accompanied by a much slower rate of molecular evolution of the PLA(2) toxins as a consequence of the snake's shift in ecological niche. This is the first case of decelerated evolution of toxins in snake venom.

Amino Acid Sequence↗
PubMed2003

Cardiovascular, haematological and neurological effects of the venom of the Papua New Guinean small-eyed snake (Micropechis ikaheka) and their neutralisation with CSL polyvalent and black snake antivenoms.

Cardiovascular and haematological effects of venom of the small-eyed Snake (Micropechis ikaheka) were examined in ventilated anaesthetised piglets. Neurotoxic effects were examined in chick biventer cervicis nerve-muscle preparations. Immunoreactivity of venom was tested against the monovalent antivenom components in a CSL Ltd Venom Detection Kit. Neutralisation was tested in vivo and in vitro with CSL Ltd polyvalent snake and Black Snake (Pseudechis australis) antivenoms. Venom in 0.1% bovine serum albumin in saline was infused into piglets in doses 1-2000 microg/kg. Pulmonary hypertension (P= 0.0007) and depression of cardiac output (P= 0.002) were observed up to 3 h after 150-160 microg/kg. The concentration of plasma free-haemoglobin increased more than 50-fold, indicating haemolysis. Neither coagulopathy nor thrombocytopenia occurred. Creatine phosphokinase and serum potassium levels did not increase suggesting absence of acute rhabdomyolysis. The venom caused post-synaptic neurotoxicty. Immunoreactivity of venom with Black Snake antivenom was observed at very high venom concentrations. Cardiovascular effects were absent and haemolysis was less after venom was pre-incubated at 37 degrees C for 30 min with polyvalent antivenom. Neutralisation by Black Snake antivenom was less effective. The neurotoxicity was neutralised by polyvalent or Black Snake antivenoms. Human envenomation may be treated with CSL Ltd polyvalent snake antivenom.

Animals↗
PubMedDate not supplied

Non-venomous snake bite and snake bite without envenoming in a Brazilian teaching hospital. Analysis of 91 cases.

A retrospective survey of 473 cases of snake bite admitted to a Brazilian teaching hospital from 1984 to 1990 revealed 91 cases of bite without envenoming and/or caused by non-venomous snakes. In 17 of these cases the snake was identified, and one patient was bitten by a snake-like reptile (Amphisbaena mertensii). In 43 cases diagnosis was made on clinical grounds (fang marks in the absence of signs of envenoming). The other 30 cases were of patients who complained of being bitten but who did not show any sign of envenoming or fang mark. Most cases occurred in men (66;73%), in the 10-19 years age group (26;29%), in the lower limbs (51/74;69%), between 6 A. M. and 2 P.M. (49;61%) and in the month of April (16;18%). One patient bitten by Philodryas olfersii developed severe local pain, swelling and redness at the site of the bite, with normal clotting time. The patient bitten by Drymarcon corais was misdiagnosed as being bitten by a snake of the genus Bothrops, was given the specific antivenom, and developed anaphylaxis. One patient bitten by Sibynomorphus mikanii presented prolonged clotting time, and was also given antivenom as a case of Bothrops bite. Correct identification of venomous snakes by physicians is necessary to provide correct treatment to victims of snake bite, avoiding unnecessary distress to the patient, and overprescription of antivenom, which may eventually cause severe untoward effects.

Adolescent↗
PubMed1976

[Occurrence of Salmonella in healthy snakes and snake cadavers- isolation of a new Salmonella species belonging to the sub-genus IV (S. IV 18:Z36, Z38:-) (AUTHOR'S TRANSL)].

Forty-seven isolation attempts performed with 20 fecal samples of exotic snakes yielded 27 Salmonella species belonging to the sub-genus I-IV. The majority of isolates (78.7%), however, was identified as sub-genus III (Arizona). The snakes under study were hold captured for less than one year (one part) or for longer than one year. Bacteriological investigations of the 7 snakes studied, repeated 7 to 21 months thereafter, revealed uniformly other Salmonella species in comparison to those found at primary examination. Necropsy investigations were performed with materials from 3 snakes. One Salmonella species (Arizona) was isolated from the colon of one snake presenting with massive necrotic enteritis. The results with blood, bile and other colon sections were negative. Several Salmonella species were found in the colon of two other snakes presenting with infiltrative and necrotic changes in the organs, but without any pathologic finding in the intestinal tract. A new Salmonella species belonging to the sub-genus IV (S. IV 18:Z36, Z38:-) was recovered from fecal sample of a Black Mamba (Dendroaspis polylepis) and another Cascabel snake (Crotalus durissus terrificus).

Animals↗
PubMed1983

The inactivating effect of Bothrops jararaca and Waglerophis merremii snake plasma on the coagulant activity of various snake venoms.

Plasmas of the poisonous snake Bothrops jararaca and of the non-poisonous snake Waglerophis merremii were not clotted by various snake venoms. These plasmas also inactivated venom clotting activity on human plasma. This effect was absent in snake serum and in heated snake plasma. The active fraction was isolated by gel chromatography from B. jararaca plasma and corresponded to the fibrinogen-containing fractions. It is suggested that the inactivation by snake plasma of the venom coagulant activity might be due to a fibrinogen-bound complex or to fibrinogen itself.

Animals↗
PubMed2003

Comparison of the in vitro neuromuscular activity of venom from three Australian snakes (Hoplocephalus stephensi, Austrelaps superbus and Notechis scutatus): efficacy of tiger snake antivenom.

1. Tiger snake antivenom, raised against Notechis scutatus venom, is indicated not only for the treatment of envenomation by this snake, but also that of the copperhead (Austrelaps superbus) and Stephen's banded snake (Hoplocephalus stephensi). The present study compared the neuromuscular pharmacology of venom from these snakes and the in vitro efficacy of tiger snake antivenom. 2. In chick biventer cervicis muscle and mouse phrenic nerve diaphragm preparations, all venoms (3-10 microg/mL) produced inhibition of indirect twitches. In the biventer muscle, venoms (10 micro g/mL) inhibited responses to acetylcholine (1 mmol/L) and carbachol (20 micromol/L), but not KCl (40 mmol/L). The prior (10 min) administration of 1 unit/mL antivenom markedly attenuated the neurotoxic effects of A. superbus and N. scutatus venoms (10 microg/mL), but was less effective against H. stephensi venom (10 microg/mL); 5 units/mL antivenom attenuated the neurotoxic activity of all venoms. 3. Administration of 5 units/mL antivenom at t90 partially reversed, over a period of 3 h, the inhibition of twitches produced by N. scutatus (10 microg/mL; 41% recovery), A. superbus (10 microg/mL; 25% recovery) and H. stephensi (10 microg/mL; 50% recovery) venoms. All venoms (10-100 microg/mL) also displayed signs of in vitro myotoxicity. 4. The results of the present study indicate that all three venoms contain neurotoxic activity that is effectively attenuated by tiger snake antivenom.

Agkistrodon↗