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PubMed2000

Chemosensitive conductance and inositol 1,4,5-trisphosphate-induced conductance in snake vomeronasal receptor neurons.

Snake vomeronasal receptor neurons in slice preparations were studied using the patch-clamp technique in the conventional and nystatin-perforated whole-cell configurations. The mean resting potential was approximately -70 mV; the average input resistance was 3 GOmega. Neurons required current injection of only 1-10 pA to display a variety of spiking patterns. Intracellular dialysis of 100 microM inositol 1,4,5-trisphosphate (IP(3)) evoked an inward current in 38% of neurons, with an average peak amplitude of 16.4 +/- 2.8 pA at a holding potential of -70mV. Application of 100 microM 3-deoxy-3-fluoro-D-myo-inositol 1,4,5-trisphosphate (F-IP(3)), a derivative of IP(3), also evoked an inward current in 4/8 (50%) neurons (32.6 +/- 58 pA at -70 mV, n = 4). The reversal potentials of the induced components were estimated to be -14 +/- 5 mV for IP(3) and -17 +/- 3 mV for F-IP(3). Bathing the neurons in 10 microM ruthenium red solution greatly reduced the IP(3)-evoked inward current to 1.6 +/- 1.1 pA at -70 mV (n = 6). With Cs(+)-containing internal solution, neither the Ca(2+)-ATPase inhibitor thapsigargin (1-50 microM) nor the Ca(2+)-ionophore ionomycin (10 microM) evoked a significant current response, suggesting that IP(3) can elicit current response in the neurons without mediation by intracellular Ca(2+) stores. Intracellular application of 1 mM cAMP evoked no detectable current response. Extracellular application of chemoattractant for snakes evoked a very large inward current. The reversal potential of the chemoattractant-induced current was similar to that of the IP(3)-induced current. The present results suggest that IP(3) may act as a second messenger in the transduction of chemoattractants in the garter snake vomeronasal organ.

Animals↗
PubMed1999

Quantitation of pyrethrum residues in brown tree snakes.

A reversed-phase solid-phase extraction-gas chromatography (SPE-GC)-electron capture detection method is developed to quantitate individual rethrin residues in pyrethrum-exposed brown tree snakes. Aliquots (6 g) of homogenized snake tissue are extracted with 10 mL acetonitrile. The rethrins are recovered from the acetonitrile extract and concentrated using C8 SPE. The rethrins are eluted from the SPE column with pentane, evaporated to near dryness, and reconstituted to 1 mL with 1-propanol. Individual rethrins are quantitated using GC analysis of the 1-propanol solution. Method limits of detection for rethrins range from 0.63 to 6.51 ng/g. The mean recovery for all rethrins is 70.8% with a standard deviation of 5.7%. This method is used to successfully quantitate incurred rethrin residues in pyrethrum-exposed brown tree snakes.

1-Propanol↗
PubMed1987

An epidemiological study of the occurrence of habu snake bite on the Amami Islands, Japan.

This study was carried out in order to estimate the risk of habu snake bite on the Amami Islands in relation to meteorological and human behavioural factors. A time-series analysis of the seasonal variation of habu snake bite was also carried out in order to clarify the possible mechanism of the epidemiological features of habu bite. It was found that the risk of habu bite has been decreasing over a long period of time on both the islands of Amamioshima and Tokunoshima. In general, the risk is higher on Tokunoshima for males and on Amamioshima it is higher for females. There was a significant positive correlation between risk and time spent in the sugar cane fields. Analysis of annual cumulative risk revealed that the inhabitants of Tokunoshima were more likely to be bitten by the habu than those of Amamioshima. The probable explanation for this was the difference between the two islands in the size of cultivated area or the proportion of the labour force engaged in primary industry. Seasonal variation of habu bite showed a maximum occurrence in June. This seasonality was probably caused by the effects of climate on the activities of both humans and habu snakes. Meteorological conditions were investigated by multiple regression analysis for causal effects on the seasonal variation in the occurrence of habu bite; as a result, temperature and humidity were presumed to have an important influence. These facts supplied the most probable explanation for the highest incidence of habu bite being in June rather than in August--the hottest season--on the Amami Islands.

Activities of Daily Living↗
PubMed2002

Phosphoglucose isomerases of hagfish, zebrafish, gray mullet, toad, and snake, with reference to the evolution of the genes in vertebrates.

Phosphoglucose isomerase (PGI) is a protein with multiple functions. To infer its structure changes and evolution in vertebrates, we cloned cDNAs encoding PGI genes from hagfish (Paramyxine yangi), gray mullet (Mugil cephalus), zebrafish (Danio rerio), toad (Bufo melanosticus), and snake (Boiga kraepelini). Only one PGI gene was cloned in each of hagfish, toad, and snake, but two PGI genes were found in zebrafish and gray mullet, respectively. The PGI of hagfish encodes 554 amino acids, in contrast to the PGIs of bonyfishes, toad, and snake which encode 553 amino acids and the PGIs of mammals which encode 558 amino acids. Among 558 aligned amino acid sites, there are 314 sites (56.27%) totally conserved. To see if diversifying selection acts on PGI amino acids of vertebrates, we calculated the pairwise ratio of nonsynonymous versus synonymous substitution per site (Ka/Ks) and the ratio of radical amino acid changes versus conservative amino acid changes per sites (dR/dC) between PGI sequences. The average pairwise ratio between nonsynonymous substitutions per nucleotide (Ka) and synonymous substitutions per nucleotide (Ks) among vertebrate PGI sequences equals 0.047 +/- 0.019. The average pairwise ratio between radical amino acid changes and conservative amino acid changes (dR/dC) among the vertebrate PGIs equal 0.938 +/- 0.158 for charge changes, 0.558 +/- 0.085 for polarity changes, and 0.465 +/- 0.0714 when both polarity and volume are considered. There is no amino acid within the vertebrate PGIs under diversifying selection as analyzed by the method of Yang et al. (2000b). The results suggest that the present vertebrate PGIs are at evolutionary stasis and are being subjected to intense purifying selection. The purifying selection is to maintain polarity and volume of the protein but not the charge groups of amino acids. Phylogenetic analysis reveals that vertebrate PGIs can be classified into three major groups: the mammalian, amphibian-reptilian, and teleostean PGIs. The gene tree suggests that the gene duplication event of PGI in bonyfishes occurred before diversification of Acanthopterygii but after the split of bonyfishes and tetrapods. The evolution of multiple functions of PGI is discussed.

Amino Acid Sequence↗
PubMed1997

Snake bites by the jararacuçu (Bothrops jararacussu): clinicopathological studies of 29 proven cases in São Paulo State, Brazil.

The jararacuçu, one of the most dreaded snakes of Brazil, southern Bolivia, Paraguay and northeastern Argentina, is a heavily-built pit viper which may grow to a length of 2.2 m. Up to 1000 mg (dry weight) of highly-lethal venom may be milked from its venom glands on a single occasion. It has accounted for 0.8% to 10% of series of snake bites in São Paulo State, Brazil. We examined 29 cases of proven jararacuçu bites recruited over a 20-year period in two São Paulo hospitals. Severe signs of local and systemic envenoming, (local necrosis, shock, spontaneous systemic bleeding, renal failure) were seen only in patients bitten by snakes longer than 50 cm; bites by shorter specimens were more likely to cause incoagulable blood. Fourteen patients developed coagulopathy, six local necrosis (requiring amputation in one) and five local abscesses. Two became shocked and four developed renal failure. Three patients, aged 3, 11 and 65 years, died 18.75, 27.75 and 83 h after being bitten, with respiratory and circulatory failure despite large doses of specific antivenom and intensive-care-unit management. In two patients, autopsies revealed acute renal tubular necrosis, cerebral oedema, haemorrhagic rhabdomyolysis at the site of the bite and disseminated intravascular coagulation. In one survivor with chronic renal failure, renal biopsy showed bilateral cortical necrosis; the patient remains dependent on haemodialysis. Effects of polyspecific Bothrops antivenom were not impressive, and it has been suggested that anti-Bothrops and anti-Crotalus antivenoms should be given in combination.

Adult↗
PubMed1994

Pyogenic granuloma of the cornea induced by "snake oil".

A pyogenic granuloma of the cornea developed on the vascularized cornea of a 79-year-old woman after "snake oil" accidentally dripped in her eye. The snake oil was being used to relieve forehead pain, which may have been referred. The five previously reported examples of corneal pyogenic granuloma are similar to this case in that trauma preceded development of the lesion. However, the chemical trauma induced by the snake oil appears to be a unique mechanism of injury.

Aged↗
PubMed2001

Systemic cytokine response in children bitten by snakes in Costa Rica.

BACKGROUND: To characterize the host response to venom from snakes of the family Viperidae in Costa Rica, we investigated the release of cytokines: IL-1, IL-6, IL-8, TNF-alpha, MIP-1beta, and RANTES in pediatric patients who were bitten by a snake. METHODS: Patients were included in this study if they were admitted to the hospital within 24 hours of the snakebite. Blood samples were taken immediately on admission to the hospital, and then at intervals of 3, 12, and 24 hours, and on days 3, 5, and 7 after the accident. Patients received gentamicin plus clindamycin or gentamicin plus penicillin intravenously for a minimum of 3 days or longer if necessary. IL-1, IL-8, TNF-alpha, MIP-1beta, and RANTES were determined by monoclonal antibody-based ELISAs, while IL-6 was determined by bioassay. RESULTS: Eighteen patients were included in this study; 15 were bitten by Bothrops asper and three by B. lateralis. Eleven patients were male. Median (range) age was 9 (1-12) years. Nine patients had detectable serum concentrations of IL-6 (200 pg/ mL) and IL-8 (51 pg/mL) on admission, increasing to 500 pg/mL and 115 pg/mL for IL-6 and IL-8, respectively, during the first 12-24 hours. Cytokine concentrations returned to normal or undetectable ranges by 72 hours. TNF-alpha concentrations peaked at 12 hours (mean: 48 pg/mL). Low, but detectable concentrations of MIP-1beta were observed in some patients at various time intervals (48 pg/mL), whereas IL-1 was not detectable at any time point. Regulated on Activation Normal T cell Expressed and Secreted (RANTES) concentrations were evaluated in only five patients, being elevated in all of them. Patients with elevated cytokine concentrations required early fasciotomy (<24 hours after the accident) more often than those who had normal or undetectable cytokine concentrations (P < 0.05). There were no statistically significant associations between severity of envenomation, or outcome, and elevated serum cytokine concentrations (P > 0.05). CONCLUSIONS: Bothrops sp snake venoms induce clinical and pathophysiologic alterations similar to acute trauma, with release of proinflammatory cytokines. A better understanding of the role of the inflammatory response could lead to the development of new therapeutic strategies to improve the outcome in snakebitten patients.

Animals↗
PubMed2003

Reproductive strategies in snakes.

Snakes of both sexes display remarkable flexibility and diversity in their reproductive tactics. Many features of reproduction in female snakes (such as reproductive mode and frequency, seasonality and multiple mating) allow flexible maternal control. For example, females can manipulate not only the genotypes of their offspring (through mate choice or enhanced sperm competition) but also the phenotypes of their offspring (through allocation 'decisions', behavioural and physiological thermoregulation, and nest-site selection). Reliance on stored energy ('capital') to fuel breeding results in low frequencies of female reproduction and, in extreme cases, semelparity. A sophisticated vomeronasal system not only allows male snakes to locate reproductive females by following scent trails, but also facilitates pheromonally mediated mate choice by males. Male-male rivalry takes diverse forms, including female mimicry and mate guarding; combat bouts impose strong selection for large body size in males of some species. Intraspecific (geographical) variation and phenotypic plasticity in a wide array of reproductive traits (offspring size and number; reproductive frequency; incidence of multiple mating; male tactics such as mate guarding and combat; mate choice criteria) provide exceptional opportunities for future studies.

Animals↗
PubMed1990

Shed snake skin and hairless mouse skin as model membranes for human skin during permeation studies.

Difficulties in obtaining and using human skin have tempted many workers to employ animal membranes for percutaneous absorption studies. We have investigated the suitability of two species of snake (Elaphe obsoleta, Python molurus) for this purpose and compared our in vitro experimental results for human skin and for hairless mouse, a currently popular model. The effects of long-term hydration on the membranes were investigated over 8 d using tritiated water as a model permeant. The initial permeability coefficients of all the membranes were similar (0.74-2.2 X 10(-3) cm 2h-1). Although the human and squamate skins did not change significantly over the test period, the permeability of hairless mouse skin increased 37 times. The actions of typical enhancers on the permeabilities of the membranes to a model penetrant 5-fluorouracil (5-FU) were tested using 3% Azone in Tween 20/saline, propylene glycol (PG), 2% Azone in PG, and 5% oleic acid in PG. While the data from snake membranes tended to underestimate the enhancer effects, those from hairless mouse skin greatly overestimated the changes. None of the membranes was a completely reliable model for assessing human percutaneous absorption as modified by accelerants. Pretreatment with acetone did not significantly change the permeability of human or squamate skins to 5-FU, although that of hairless mouse increased twentyfold. An overall conclusion is that, wherever possible, human skin should be used in absorption studies and not hairless mouse or snake skin; otherwise, misleading results may be obtained.

Acetone↗
PubMed1984

A preliminary study on the use of carbenicillin in snakes.

The results of a 10 year survey on the in vitro antibiotic resistance patterns of Pseudomonas spp. isolated from clinically ill reptiles, showed a high degree of sensitivity to carbenicillin. On the basis of sensitivity testing, carbenicillin was used to treat nine snakes of four different species, with confirmed Pseudomonas infections. Plasma carbenicillin levels were assayed, by a microbiological agar diffusion technique, at intervals of time after a single intramuscular injection at a dose rate of 400 mg/kg. Peak plasma levels of 177 and 270 micrograms/ml were reached 1 h after the initial injection and therapeutic levels persisted for at least 12 h. This initial study indicated that a suggested dose regime in snakes, derived by extrapolation from mammalian dosages, of 100-125 mg/kg daily was insufficient to produce plasma levels of sufficient magnitude and duration to effectively treat Pseudomonas infections in snakes.

Animals↗
PubMed2005

Population genetic analysis identifies source-sink dynamics for two sympatric garter snake species (Thamnophis elegans and Thamnophis sirtalis).

Population genetic structure can be shaped by multiple ecological and evolutionary factors, but the genetic consequences of these factors for multiple species inhabiting the same environment remain unexplored. We used microsatellite markers to examine the population structures of two coexisting species of garter snake, Thamnophis elegans and Thamnophis sirtalis, to determine if shared landscape and biology imposed similar population genetic structures. These snakes inhabit a series of ponds, lakes and flooded meadows in northern California and tend to converge on prey type wherever they coexist. Both garter snakes had comparable effective population sizes and bidirectional migration rates (estimated using a maximum-likelihood method based on the coalescent) with low but significant levels of genetic differentiation (F(ST) = 0.024 for T. elegans and 0.035 for T. sirtalis). Asymmetrical gene flow revealed large source populations for both species as well as potential sinks, suggesting frequent extinction-recolonization and metapopulation dynamics. In addition, we found a significant correlation between their genetic structures based on both pairwise F(ST)s for shared populations (P = 0.009) and for bidirectional migration rates (P = 0.024). Possible ecological and evolutionary factors influencing similarities and differences in genetic structure for the two species are discussed. Genetic measures of effective population size and migration rates obtained in this study are also compared with estimates obtained from mark-recapture data.

Animal Migration↗
PubMed2006

Analysis of the transmission of Salmonella spp. through generations of pet snakes.

Besides the 'classical' animals known as reservoirs for Salmonella spp., like poultry and cattle, reptiles have emerged as a significant source of human salmonellae infections during the last years. Reptile-associated salmonellae frequently cause severe clinical courses including fatalities due to septicaemia and meningitis. Therefore, it is of major priority to develop measures which may help preventing cases of reptile-associated salmonellae. However, as a first step the epidemiology of salmonellae in reptiles must be understood. Therefore, in this study a population analysis of the salmonellae of two female snakes was performed and the pattern of inheritance of salmonellae to their offspring was investigated. It is demonstrated that adult snakes usually harbour a population of concurrent salmonellae serovars. Colonization of their offspring during pregnancy and birth is a significant way of transmission causing 65% of the newborn to be positive for salmonellae. The effectiveness of the transmission does not seem to be due only to the frequency of a certain serovar, because the most prevailing strain of one female snake was not detectable in any of her offspring.

Animals↗
PubMed2003

PCR-mediated recombination between Cryptosporidium spp. of lizards and snakes.

The presence or absence of genetic recombination has often been used as one of the criteria for Cryptosporidium species designation and population structure delineation. During a recent study of cryptosporidiosis in reptiles that were housed in the same room, 4 lizards were found to have concurrent infections of C. serpentis (a gastric parasite) and C. saurophilum (an intestinal parasite), and 6 snakes were concurrently infected with C. serpentis, C. saurophilum and a new Cryptosporidium as indicated by PCR-RFLP analysis of the SSU rRNA gene. DNA sequence analysis of cloned PCR products confirmed the diagnosis of mixed infections. Surprisingly, it appeared that 11 of the 22 clones (8 and 14 clones from a lizard and a snake, respectively) had chimeric sequences of two Cryptosporidium spp. BootScan analysis indicated the existence of recombinants among the cloned sequences and detection of the informative sites confirmed the BootScan results. Because the probability for genetic recombination between gastric and intestinal parasites is small, these hybrid sequences were likely results of PCR artifacts due to the presence of multiple templates. This was confirmed by PCR-sequencing analysis of single-copy templates using diluted DNA samples. Direct sequencing of 69 PCR products from 100- to 1,000-fold diluted DNAs from the same snake and lizard produced only sequences of C. serpentis, C. saurophilum and the unnamed Cryptosporidium sp. Thus, care should be taken to eliminate PCR artifacts when determining the presence of genetic recombination or interpreting results of population genetic studies.

Animals↗
PubMed1978

Snake bite in cats.

In 6 years snake bite was diagnosed in 41 cats, with an average age of 20 months. The commonest presenting signs were dilated pupils, absence of the pupillary light reflex, depression and generalised muscle weakness. Other frequent findings were vomiting, dyspnoea, hindlimb ataxia and complete flaccid paralysis. Thirty-seven cases (90%) occurred in the 6 warmer months of the year. Tiger snakes were positively identified in 7 cases. A recovery rate of 89% was obtained in cases receiving 3000 units Tiger snake antivenene, fluid therapy and nursing. Cases presenting with a complete flaccid paralysis and sub-normal temperatures were poor prognostic risks.

Animals↗
PubMed1979

Snake bite in dogs.

In 7 years snake bite was diagnosed in 80 dogs. Sporting breeds figured prominently. The average was 3.6 years. The commonest presenting signs were salivation, vomiting, dilated pupils, absence of the pupillary light reflex, depression and generalised muscle weakness, hindlimb ataxia and respiratory distress. Sixty-seven cases (84%) occurred in 6 warmer months on the year. Fifty-one dogs (64%) were seen either to be bitten or in contact with a snake. Tiger and Brown snakes were implicated on 32 and 3 occasions respectively. An overall recovery rate of 87% was obtained for patients receiving antivenene, fluid and support therapy. The period from treatment-to-full recovery was shorter for cases in which the bite-to-treatment period was one hour or less (24 hours) when compared with the recovery time for all cases (36 hours). The prognosis was poor for dogs presenting with the triad of complete flaccid paralysis, dyspnoea and a sub-normal temperature.

Animals↗
PubMed2006

Anuric renal failure in a dog after red-bellied black snake (Pseudechis porphyriacus) envenomation.

A case of Red-bellied Black snake envenomation resulting in intravascular haemolytic anaemia, rhabdomyolysis and anuric renal failure is described in the dog. A 12-year-old female desexed Golden Retriever was presented with a 15 hour history of profuse salivation, progressive lethargy, obtundence, inappetence and collapse. Significant findings on clinical examination were pallor, icterus, tachypnoea and dyspnoea with increased respiratory sounds and crackles in all lung fields. Generalised abdominal and muscular pain was apparent and dark red-brown urine was present around the perineal region. A diagnosis of Red-bellied Black snake (Pseudechis porphyriacus) envenomation was made and the dog was treated with intravenous fluid therapy, Tiger/Brown snake antivenom, packed red cell transfusions and Intermittent Positive Pressure Ventilation. Continued clinical deterioration occurred and a diagnosis of acute renal failure secondary to myohaemoglobinuric pigmenturia was made 12 hours after admission. Intensive treatment was attempted with diuresis and volume expansion. Oliguria and subsequent anuria ensued and the dog was euthanased due to a grave prognosis and lack of clinical response to treatment. Necropsy examination revealed muscular necrosis, accumulation of fluid in the thoracic and peritoneal cavities, and marked renal tubular necrosis with intraluminal occlusion secondary to pigmentary casts.

Acute Kidney Injury↗
PubMed1999

Low dose subcutaneous adrenaline to prevent acute adverse reactions to antivenom serum in people bitten by snakes: randomised, placebo controlled trial.

OBJECTIVE: To assess the efficacy and safety of low dose adrenaline injected subcutaneously to prevent acute adverse reactions to polyspecific antivenom serum in patients admitted to hospital after snake bite. DESIGN: Prospective, double blind, randomised, placebo controlled trial. SETTING: District general hospital in Sri Lanka. SUBJECTS: 105 patients with signs of envenomation after snake bite, randomised to receive either adrenaline (cases) or placebo (controls) immediately before infusion of antivenom serum. INTERVENTIONS: Adrenaline 0.25 ml (1:1000). MAIN OUTCOME MEASURES: Development of acute adverse reactions to serum and side effects attributable to adrenaline. RESULTS: 56 patients (cases) received adrenaline and 49 (controls) received placebo as pretreatment. Six (11%) adrenaline patients and 21 (43%) control patients developed acute adverse reactions to antivenom serum (P=0.0002). Significant reductions in acute adverse reactions to serum were also seen in the adrenaline patients for each category of mild, moderate, and severe reactions. There were no significant adverse effects attributable to adrenaline. CONCLUSIONS: Use of 0.25 ml of 1:1000 adrenaline given subcutaneously immediately before administration of antivenom serum to patients with envenomation after snake bite reduces the incidence of acute adverse reactions to serum.

Administration, Cutaneous↗
PubMed2005

Fatal acute disseminated encephalomyelitis following treated snake bite in India.

Snake bite is an important cause of mortality and morbidity in India, with an estimated 35,000 to 50,000 fatal bites occurring annually. The neurological consequences of snake bite are predominantly the result of inhibition of neuromuscular transmission. We describe the first documented case of autopsy proven acute disseminated encephalomyelitis following treated snake bite in a young female.

Adult↗