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PubMedDate not supplied

Ten years of snake bites at Fremantle Hospital.

Seventy-six patients (30% children) were admitted to Fremantle Hospital over 10 years with suspected snake bite. Twenty-nine patients were definitely bitten, with 26 bites being witnessed. Of the 13 patients definitely envenomated, 11 had a coagulopathy although seven were asymptomatic; four other patients may have been envenomated. The dugite (Pseudonaja affinis) was probably responsible for most envenomations. Eleven of the 13 envenomated patients received antivenom (six brown snake, four polyvalent and one tiger snake antivenom). The patient envenomated by the tiger snake (Notechis ater occidentalis), a 13-year-old girl, was initially incorrectly treated with brown snake antivenom at a country hospital, and did not receive appropriate antivenom until 50 hours after the bite. She developed profound paralysis, rhabdomyolysis and renal failure, and required prolonged ventilation during her 53-day hospital admission, but survived without disability. Snake bite wounds should not be washed, so that venom can be identified from the wound. Attempts to kill snakes are dangerous, often leading to bites on the fingers. First aid measures of a pressure bandage and immobilisation, used in 13 of the 29 cases (45%), should be more widely publicised.

Adolescent↗
PubMed1997

Gnathostomiasis in frog-eating snakes from Japan.

Gnathostoma doloresi parasitizes the gastric wall of wild (boars) and domestic (pigs) swine (Sus scrofa). Its larvae cause cutaneous larva migrans in humans. Amphibians, reptiles and a freshwater fish are infected with the advanced 3rd stage larvae. Prevalence of G. doloresi larvae were surveyed in several snakes, especially in a common frog-eating snake (Rhabdophis tigrinus). All species of snakes examined were infected with G. doloresi larvae suggesting that snakes are important reservoir hosts. Prevalence of G. doloresi larvae in frog-eating snakes was lower than that found in mammal-eating snakes. Thus, as a source of infection to snakes, small mammals may be more important than frogs in the natural life cycle of G. doloresi in Japan.

Animals↗
PubMed1999

Fatal mycotic dermatitis in captive brown tree snakes (Boiga irregularis).

Cutaneous fungal infections occurred in four captive brown tree snakes (Boiga irregularis). The ventral scales were most commonly affected, and lesions began as areas of erythema and edema with vesicle formation, followed by development of caseous brown plaques. Lesions usually started where ventral scales overlapped and spread rapidly. All snakes died within 14 days after clinical signs were first noted. The deaths of three of the snakes were directly attributable to the cutaneous disease; the other snake died from renal failure and visceral gout, most likely induced by gentamicin therapy. Histologically, lesions consisted of epidermal hyperplasia and hyperkeratosis, with foci of epidermal necrosis, intraepidermal vesicle formation, and subacute inflammation of the underlying dermis. These lesions were associated with bacteria and numerous septate, branched fungal hyphae within the epidermis and overlying serocelluar crusts. Hyphae that penetrated through the superficial surface of the epidermis often formed terminal arthroconidia. The same species of fungus was isolated in pure culture from the skin of three snakes, but fungal cultures were not performed on samples from the fourth snake. The fungus has been identified as the Chrysosporium anamorph of Nannizziopsis vriesii based on its formation of solitary dermatophytelike aleurioconidia and alternate and fission arthroconidia. The source of the fungus in this outbreak was not determined; however, the warm, moist conditions under which the snakes were housed likely predisposed them to opportunistic cutaneous fungal infections.

Animals↗
PubMed2001

Normal oral bacterial flora from some southern African snakes.

Eighteen snakes representing 11 species were subject to mouth swabbing on 58 occasions. Of these swabs, 52.2% were positive for bacteria. A total of 92 bacterial isolates were cultured, representing 30 species of which 81.5% were Enterobacteriaceae, 16.3% gram positive cocci, and 2.2% anaerobes. Swabs from non-venomous snakes were more commonly bacteriologically sterile than those from venomous snakes (P = 0.0107). The oral bacterial flora did not differ between captive and newly captured snakes. The bacterial species found were not constant in a single snake with time, in the same snake species, the same serpentarium or geographically. The bacteria most commonly cultured were Proteus spp., Pseudomonas spp., Salmonella arizonae and Staphylococcus epidermidis. Colony counts tended to be low. Three or more bacterial species per venomous snake per occasion were more common in winter than summer (P= 0.0192).

Animals↗
PubMed2006

Comparison of the percutaneous absorption of hydrophilic and lipophilic compounds in shed snake skin and human skin.

The in vitro transdermal permeation of eight hydrophilic drugs (antipyrine, L-dopa, dopamine hydrochloride, diclofenac sodium, 5-fluorouracil, isoprenaline hydrochloride, nicorandil and morphine hydrochloride) and eight lipophilic drugs (aminopyrine, cyclobarbital, ibuprofen, indomethacin, isosorbide dinitrate, flurbiprofen, ketoprofen and lignocaine) was determined using shed snake skin of Elaphae obsoleta and human skin. The permeation parameters and physiological characteristics of the skin, e.g. the water and lipid content, and the thickness of shed snake skin and human skin were evaluated and compared. In shed snake skin, the permeability coefficients (P) of lipophilic drugs were in the same range as those through the human skin (0.9 to 1.8-times); whereas those of hydrophilic drugs were remarkably lower (3.3 to 6.1-times). The thickness and lipid content of shed snake skin and human stratum corneum were not significantly different (P > 0.05), whereas the water content of shed snake skin was significantly lower than that of human stratum corneum (P < 0.05). The lower permeability of shed snake skin for hydrophilic compounds might be caused by the lower porosity of skin strata. The results suggested a potential use of shed snake skin as barrier membrane for lipophilic compounds percutaneous absorption studies in vitro.

Animals↗
PubMed1990

Purification and characterization of a chemoattractant from electric shock-induced earthworm secretion, its receptor binding, and signal transduction through the vomeronasal system of garter snakes.

Following shocks with low voltage electric current, earthworms, Lumbricus terrestris, secrete a yellow mucus that has alarm properties for conspecifics and chemoattractive properties for garter snakes, Thamnophis sirtalis. A proteinaceous chemoattractant for garter snakes has been isolated and purified to homogeneity from such secretions by means of permeation chromatography and semipreparative nondenaturing polyacrylamide gel electrophoresis. The purified protein is highly attractive to garter snakes; it loses its activity after proteolytic digestion. It is a glycoprotein consisting of a single polypeptide chain with an NH2-terminal alanine. This chemoattractant has a minimum molecular mass of 15.4 kDa calculated from its amino acid and carbohydrate contents and an apparent molecular mass of about 20 kDa as estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It has a pI of about 4.0, and it binds wheat germ agglutinin but not concanavalin A. This chemoattractant shows a protein to carbohydrate ratio of 2.0 +/- 0.08 (n = 5) and a ratio of total sugar to amino sugar of 1.9 +/- 0.08 (n = 3). The sequence of its NH2-terminal 15 amino acid residues has been determined. Studies were also conducted on the chemosignal transduction through the vomeronasal sensory system of the garter snake. Dot blot analysis showed that the purified chemoattractant bound to snake vomeronasal sensory epithelial membrane fractions. It did not bind to membrane extracts of the nonsensory epithelium of the vomeronasal mushroom body. The chemoattractant also bound specifically to vomeronasal sensory epithelial membrane in a reversible and saturable fashion with Kd and Bmax values of about 0.3 microM and 0.4 nmol/mg of protein, respectively. In electrophysiological studies, the chemoattractant applied to the vomeronasal epithelium caused an increase in firing rate of individual neurons in the accessory olfactory bulb of garter snakes, the projection site for vomeronasal neurons. The present results are the first clear biochemical and electrophysiological evidence for a vomeronasal epithelium response to a purified nonvolatile odorant, and this makes the garter snake vomeronasal system ideal for studying the mechanisms of chemosignal transduction.

Amino Acids↗
PubMedDate not supplied

[Data on the biological cycle of the ascaridoid Ophidascaris trichuriformis, parasite of snakes].

Ophidascaris trichuriformis is an ascaridoid commonly found in some species of Colubridae snakes. Similarly to what has been observed with several ascaridoid species, in O. trichuriformis the larvae, when still inside the egg-shells, reach the 3th snake stage around the 8th day of incubation in cultures kept at around 25 degrees C. Tentative assays to infect mice, snakes, toads, fish, and tadpoles of Hyla fuscovaria and Bufo sp. was made through the administration of embryonated eggs. Eggs didn't even eclode in mice, snakes or toads in such experiments; while in fish, although the eggs ecloded, its larvae were eliminated after the 4th day. In H. fuscovaria and Bufo sp. tadpoles, larvae were liberated from egg-shells and their development was observed up to the 36th day. They grew from the 6th hour to the above mentioned day, after which larvae were longer in Bufo sp. than in H. fuscovaria. By the 36th day distinction of sexes was possible through examination of genital primordia whose morphology and location differed in male and female larvae. From the 30th day on, following the recognizable beginning of metamorphosis in anuran amphibians and going up to the 65th day after experimental infection, an intense growth of the larvae infecting Bufo sp. was observed; the growth of such larvae was negligible between the 65th and the 85th days. Five snakes (Waglerophis merremii) were given per os larvae obtained from Bufo sp. after the 65th day of infection; these snakes died on the 53th, 54th, 60th, 110th and 116th days after their own infection, respectively, and in each of then 4th stage O. trichuriformis larvae were found in the stomach. The gastric location of such larvae in each snake was identical to the one in which adult worms of this same species are regularly found in natural infections: all of them had the middle part of the body embedded into the stomach wall while both anterior and posterior extremities kept free towards the lumen of the organ.

Animals↗
PubMed1997

[Acetylcholinesterase from snake venoms].

Acetylcholinesterase (AChE) plays a key role in cholinergic transmission. For example, located at the neuro-muscular junction of vertebrates, it allows a fine temporal control of muscle contraction. The presence of AChE in tissues devoid of cholinergic function is also well known and raises the question of its role. In particular, AChE occurs at high level in the venoms of Elapid snakes, except Mambas. In contrast, the venom of snakes belonging to Viperid or Colubrid families does not contain any AChE. AChE purified from snake venom consists of soluble, hydrophilic monomers. Cloning the cDNA of the venom AChE from Bungarus fasciatus showed that its C-terminal peptide is very different from those of other AChEs. This peptide is encoded by a new alternative exon, called S for Soluble and Snake. It is a short very basic peptide of 15 residues. Analysis of the venom enzyme and in vitro expression experiments showed that the last eight residues are removed in the mature protein. This cleavage is not necessary for enzymatic activity and occurs before secretion of the enzyme. AChEs from snake venoms vary in their sensitivity to peripheral site inhibitors, notably to Mambas toxins, fasciculins. While Ophiophagus AChE is as sensitive as Torpedo enzyme (IC50 around 10(-10) M), Naja and Heamacatus AChEs are insensitive to the toxin up to a concentration of 10(-6) M. Bungarus AChE has an intermediary IC50 of 10(-8) M. The analysis of its sequence shows two major differences, in the peripheral site region, when compared to Torpedo or mammalian AChEs: at position 70 it contains a methionine instead of a tyrosine and at position 285, it contains a lysine instead of an acidic residue (glutamic or aspartic acid). The modification of these residues by site-directed mutagenesis and the enzymatic analysis of modified recombinant enzymes confirmed the implication of these two residues in the properties of Bungarus AChE peripheral site. The presence of an alternative exon, used for generating a soluble form of AChE in venoms, raises interesting evolutionary questions: does it exist in snakes whose venom does not contain AChE, e.g. Mambas? did this exon preexist, for expression in other contexts? In addition snake venoms offer an exceptional system for analysing the mechanism of peripheral site inhibition, because of its wide range of sensitivity.

Acetylcholinesterase↗
PubMed1997

The painful experience of inappropriate therapy of snake bites: a report of two cases.

Recognizing the exact species of snake and specific antivenin administration are the most important modality of treatment for poisonous snake bites. In Taiwan, there are six kinds of medically important snakes--two species of Elapidae and four species of Viperidae. Two kinds of polyvalent antivenins and one monovalent antivenin are available. But for snake bites, questions about the prescription of antivenins are still the major problems addressed to the Poison Control Center. Improper use of antivenin may delay a patient's recovery from snake poisoning and even lead to mortality. Here, two cases of snake bites are presented. Each had severe complications and mortality as a result of inappropriate therapy, and the most rational management of snake bite in Taiwan is discussed, too.

Adult↗
PubMed1998

Snake bites recorded by veterinary practices in Australia.

OBJECTIVE: To determine the extent of the snake bite problem in domestic animals, its regional significance and the effects of antivenom treatment. DESIGN: A questionnaire was designed seeking information on the number and type of domestic animals referred, whether treated or untreated, type of snakes and management of the bite. PROCEDURE: The survey form was sent to 10% of veterinary surgeons, selected at random throughout Australia. RESULTS: The response of 106 veterinary surgeons revealed that snake bite in domestic animals is frequent, with an estimated 6200 cases reported annually. Bites were more prominent in rural (78%) than urban areas (22%) with brown, tiger and black snakes accounting for 76%, 113% and 6% of cases, respectively. Cats and dogs were the most frequently reported victims. Ninety-one percent of cats and 75% of dogs survived following the administration of antivenom whereas 66% of cats and 31% of dogs survived without antivenom. Overall, in 33% of cases antivenom was not used, and venom detection kits were used in only 1% of cases. A number of drugs were used in various combinations with or without antivenom and intravenous fluids in the treatment of animals with snake bite, but their role in reducing the severity of envenomations was not assessed. CLINICAL IMPLICATIONS: Antivenom significantly improves the chances of survival of domestic animals bitten by snakes.

Animals↗
PubMed2006

Venomous adversaries: a reference to snake identification, field safety, and bite-victim first aid for disaster-response personnel deploying into the hurricane-prone regions of North America.

Each hurricane season, emergency-preparedness deployment teams including but not limited to the Office of Force Readiness and Deployment of the US Public Health Service, Federal Emergency Management Agency, Deployment Medical Assistance Teams, Veterinary Medical Assistance Teams, and the US Army and Air Force National Guard are at risk for deploying into hurricane-stricken areas that harbor indigenous hazards, including those posed by venomous snakes. North America is home to 2 distinct families of venomous snakes: 1) Viperidae, which includes the rattlesnakes, copperheads, and cottonmouths; and 2) Elapidae, in which the only native species are the coral snakes. Although some of these snakes are easily identified, some are not, and many rank among the most feared and misunderstood animals. This article specifically addresses all the native species of venomous snakes that inhabit the hurricane-prone regions of North America and is intended to serve as a reference to snake identification, basic field safety procedures, and the currently recommended first-aid measures for snakebite casualties.

Animals↗
PubMed2006

Post-translational modification accounts for the presence of varied forms of nerve growth factor in Australian elapid snake venoms.

The Australian elapid snakes are amongst the most venomous snakes in the world, but much less is known about the overall venom composition in comparison to Asian and American snakes. We have used a combined approach of cDNA cloning and 2-DE with MS to identify nerve growth factor (NGF) in venoms of the Australian elapid snakes and demonstrate its neurite outgrowth activity. While a single 730 nucleotide ORF, coding for a 243 amino acid precursor protein was detected in all snakes, use of 2-DE identified NGF proteins with considerable variation in molecular size within and between the different snakes. The variation in size can be explained at least in part by N-linked glycosylation. It is possible that these modifications alter the stability, activity and other characteristics of the snake NGFs. Further characterisation is necessary to delineate the function of the individual NGF isoforms.

Amino Acid Sequence↗
PubMed1994

The development of Hepatozoon sipedon sp. nov. (Apicomplexa: Adeleina: Hepatozoidae) in its natural host, the Northern water snake (Nerodia sipedon sipedon), in the culicine vectors Culex pipiens and C. territans, and in an intermediate host, the Northern leopard frog (Rana pipiens).

The life cycle of Hepatozoon sipedon sp. nov. was studied in two snake species, the Northern water snake and the Eastern garter snake, in its mosquito hosts Culex pipiens and C. territans, and in the Northern leopard frog. Gametogenesis, fertilization and sporogony occurred within fat body cells in the haemocoel of mosquitoes that had fed on infected water snakes. Mature oocysts averaging 263 microns in diameter and containing more than 500 sporocysts were observed in mosquitoes 28 days post-feeding. Each sporocyst enclosed eight sporozoites. Dizoic cysts were found in the liver of frogs that had been fed infected mosquitoes seven days previously. Two rounds of merogony in various internal organs and intraerythrocytic gamonts were observed in snakes that had been fed frogs which had been orally inoculated with infected mosquitoes. Developmental stages were not seen in snakes that were fed infected mosquitoes directly. A comparison of this life cycle with those described for other Hepatozoon species infecting snakes is presented with reference to the different modes of transmission featured by these parasites.

Animals↗
PubMed2003

The influence of dehydration on the thermal preferences of the Western tiger snake, Notechis scutatus.

Temperature selection in tiger snakes (Notechis scutatus) is strongly influenced by hydration state and this response varies between two distinct neighbouring populations on semi-arid Carnac Island and mainland wetland (Herdsman Lake). Fed and hydrated (control) Carnac Island snakes selected a preferred body temperature of 26.2+/-1.2 degrees C and an average maximum temperature of 32.5+/-0.5 degrees C in a photo-thermal gradient. Dehydrated Carnac Island snakes selected a significantly lower preferred body temperature (19.7+/-1.6 degrees C) and average maximum temperature (27.7+/-1.0 degrees C). Control Herdsman Lake snakes selected a preferred body temperature of 27.5+/-0.6 degrees C and an average maximum temperature of 33.3+/-0.4 degrees C. Dehydrated Herdsman Lake snakes selected a significantly lower preferred body temperature (23.3+/-1.1 degrees C) and a lower average maximum temperature (31.8+/-0.6 degrees C). Thermal depression (decreased preferred body and average maximum temperatures) in response to dehydration was greater for Carnac Island than Herdsman Lake snakes. As decreases in temperature and activity can reduce water loss, our laboratory data suggest that the survival of the relict population of tiger snakes on Carnac Island is associated with thermoregulatory modifications, which may have the effect of enhancing water conservation in this waterless habitat.

Animals↗
PubMed2004

A fast snake model based on non-linear diffusion for medical image segmentation.

In this paper, the traditional snake model and gradient vector flow (GVF) snake model are studied, which are believed to be quite slow due to the need to compute inverse matrix. Actually, the GVF in the latter snake model is formed by a biased linear diffusion procedure, and there would be oscillations around the edge of the object. Based on GVF generated through non-linear diffusion, we present a fast GVF (FGVF) snake model which is much faster than the traditional snake model and GVF snake model, and would cause no degradation of stability and flexibility, meanwhile, it could reduce the oscillations around the edges. The segmentation results using FGVF and error analysis on simulated images are presented. Finally, the demonstration of FGVF applied to Computed Tomography and Magnetic Resonance images are shown, the segmentation results are satisfactory visually with much less computation time in comparison with former snakes.

Algorithms↗
PubMed2004

Molecular cloning, sequence analysis and expression of the snake follicle-stimulating hormone receptor.

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) control gonadal function in mammalian and many non-mammalian vertebrates through the interaction with their receptors, FSHR and LHR. Although the same is true for some reptilian species, in Squamata (lizards and snakes) there is no definitive evidence for the presence of either two distinct gonadotropins or two distinct gonadotropin receptors. Our aim was to characterize the gonadotropin receptor(s) of the Bothrops jararaca snake. Using a cDNA library from snake testis and amplification of the 5'-cDNA ending, we cloned a cDNA related to FSHR. Attempts to clone a cDNA more closely related to LHR were unsuccessful. Expression of FSHR mRNA was restricted to gonadal tissues. The snake FSHR is a G protein-coupled receptor with 673 amino acids, and the aminoterminal domain with 346 amino acids consists of a nine leucine-rich repeat-containing subdomain (LRR) flanked by two cysteine-rich subdomains. The beta-strands in the LRR are conserved with exception of the third, a region that may be important for FSH binding. In contrast with mammalian, avian and amphibian FSHRs, the snake FSHR presents amino acid deletions in the carboxyterminal region of the extracellular domain which are also seen in fish and lizard FSHRs. cAMP assays with the recombinant protein transiently expressed in HEK-293 cells showed that the snake FSHR is more sensitive to human FSH (hFSH) than to human chorionic gonadotropin. Phylogenetic analysis indicated that the squamate FSHRs group separately from mammalian FSHRs. Our data are consistent with the apparently unique gonadotropin-receptor system in Squamata reptilian subgroup. Knowledge about the snake FSHR structure may help identify structural determinants for receptor function.

Amino Acid Sequence↗
PubMed2004

Effects of melatonin on the behavioral and hormonal responses of red-sided garter snakes (Thamnophis sirtalis parietalis) to exogenous corticosterone.

We investigated possible interactions between melatonin and corticosterone in modulating the reproductive behavior of male red-sided garter snakes (Thamnophis sirtalis parietalis) following spring emergence. We also examined whether melatonin's modulatory actions could be explained by its potential properties as a serotonin receptor antagonist. Exogenous corticosterone significantly reduced courtship behavior of male snakes in a dose-dependent manner. Melatonin also significantly reduced courtship behavior of male garter snakes. Pretreatment with melatonin before administering corticosterone treatments further suppressed courtship behavior of red-sided garter snakes. These results indicate additive inhibitory effects of melatonin and corticosterone in modulating reproductive behavior. Snakes receiving ketanserin, a serotonergic type 2A receptor antagonist, followed by corticosterone also showed reduced courtship behavior; this serotonin receptor antagonist followed by treatment with vehicle did not significantly influence courtship behavior of male snakes. Neither melatonin nor corticosterone treatments significantly influenced testosterone + 5-alpha-dihydrotestosterone concentrations of male garter snakes, supporting a direct effect of melatonin and corticosterone on courtship behavior that is independent of any effect on androgen concentrations. We propose that a serotonin system is involved in the modulation of male courtship behavior by melatonin and corticosterone. In addition, our data support the hypothesis that melatonin may function as a serotonin receptor antagonist. Further research is necessary to discern whether the actions of melatonin and corticosterone are converging on the same pathway or if their effects on different pathways are having additive inhibitory effects on courtship behavior.

Analysis of Variance↗
PubMed2004

A molecular phylogeny of aquatic gastropods provides a new perspective on biogeographic history of the Snake River Region.

Mitochondrial DNA sequences of aquatic gastropods of the subgenus Pyrgulopsis (Natricola) were analyzed to test a commonly accepted hypothesis concerning the early history of the Snake River in the northwestern US. Distributions of Natricola and other regional biota were previously used to infer that the Snake River flowed to the Pacific through southeastern Oregon and northern California during the Neogene prior to its capture by the Columbia River in the late Pliocene (2 Ma). A molecular phylogeny based on partial sequences of COI and NDI (1149 bp) indicates that the Natricola clade is restricted to the modern Snake-Columbia River Basin and the Oregon Lakes region whereas northern California populations previously assigned to this subgenus belong to other lineages. The Natricola clade is not deeply subdivided into Oregon Lakes and Snake River Basin units consistent with late Pliocene fragmentation of the hypothesized paleodrainage, but instead is shallowly structured and contains multiple transitions among these two geographic areas. The strongly supported sister relationship between Natricola and a species from northwest Nevada (P. imperialis) is consistent with a recent proposal that the ancestral Snake River did not flow through southeast Oregon but instead flowed south to the Humboldt River. Within the context of this hypothesis, the multiple transitions between the Snake River Basin and the Oregon Lakes region that occurred within Natricola may be attributed to a late Pleistocene connection between these areas that was unrelated to the early course of the Snake River.

Animals↗