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PubMed1997

A study of epidemiology, risk factors and preventive measures against snake bites.

The epidemiology and exposing causes of snake bites were studied in 274 patients between 1 January 1982 and 30 December 1990. They comprised 142 males (51.82%) and 132 females (48.18%). Their ages ranged from 1 month to 86 years old. The age group most frequently bitten found in this study was between 15 to 29 years old amounting to 106 cases (38.69%). Of those 274 cases, 212 (77.37%) were the victims of poisonous snakes, namely, the green pit viper (Trimeresurus spp.) 156 cases (73.58%), the cobra (Naja naja) 53 cases (25.00%), Russell's viper (Vipera russellii siamensis) 3 cases (1.42%), while 13 cases (4.74%) were bitten by non-poisonous snakes, and in the remaining 49 cases (17.88%), the biting snakes were not clearly seen. It was found that 56 cases (20.44%) were bitten in the house, 50 cases (18.25%) were bitten within the precincts of the residence. However the highest number, 168 cases (61.31%) were bitten outside. It was also interesting to learn that 221 cases (80.66%) out of 274 were bitten in Bangkok, 91 cases (33.21%) were bitten from 6.00 p.m. to 9.00 p.m., 129 cases (47.08%) were bitten between June and September, 98 cases (35.77%) were bitten on a foot and 77 cases (28.10%) were bitten on a finger. The high risk factor of being bitten by a snake was walking along a farm or a ranch with masses of grass or undergrowth during the night without self-prevention and good caution. Therefore, health education on preventive measures were elucidated.

Adolescent↗
PubMed1998

Venomous snakebite in Thailand. I: Medically important snakes.

Thailand has an abundance of venomous snakes. Among the neurotoxic family Elapidae, there are three species of the genus Naja (cobras), three of the genus Bungarus (kraits), and the king cobra of the genus Ophiophagus. Other Elapidae snakes in Thailand include sea snakes and Asian coral snakes of the genus Calliophis. They have potent venoms but rarely bite humans. Tissue and hemotoxic snakes are represented by family Viperidae, subfamilies Viperinae and Crotalinae. They remain an occupational hazard for farmers and rubber tappers, causing serious morbidity but only rare deaths, since competent treatment is now widely available throughout Thailand. Purified equine antivenin is manufactured locally for the monocled and Siamese spitting cobras (Naja kaouthia and N. siamensis), king cobra (Ophiophagus hannah), banded krait (Bungarus fasciatus), most green pit vipers (Trimeresurus sp.), Malayan pit viper (Calloselasma rhodostoma), and the Siamese Russell's viper (Daboia russelli siamensis).

Animals↗
PubMed1996

Snake envenomation in cats and its detection by rapid immunoassay.

OBJECTIVE: To determine the usefulness of a snake venom detection kit (SVDK) in the management of envenomed cats. DESIGN: A clinical study. ANIMALS: Twenty-two cats were investigated. PROCEDURE: Cats injected subcutaneously with approximately 0.25 or 1.0 lethal dose (LD) of tiger snake venom or 1 or 4 LD of brown snake venom were observed for clinical symptoms of envenomation at intervals over the ensuring 24 to 48 hours(h). Blood and urine samples were taken at regular intervals and assayed in a quantitative laboratory assay for snake venoms. Selected samples were assayed in parallel in a rapid, semi-quantitative SVDK. RESULTS: The studies showed that it was important to estimate the elapsed time from envenomation to presentation. If this time was less than 8 h, blood was the most appropriate sample and a negative result should exclude serious envenomation. If the elapsed time exceeded 8 h, it was essential that urine be sampled. Venom levels in urine were high at 8 h and approached the level of test sensitivity over 24 to 48 h; however by this time clinical signs were obvious in endangered cats. CONCLUSIONS: Careful use of the SVDK is a valuable aid in the management of a potentially envenomed cat.

Animals↗
PubMed2003

Transvaginal sonographic appearance of thrombosed uterine arteries after uterine artery embolization: the "white snake" sign.

PURPOSE: The aim of this prospective study was to describe the appearance of thrombosed uterine arteries on transvaginal sonography performed after uterine artery embolization (UAE) and to assess the prognostic value of the "white snake" sign with regard to symptomatic outcome at 12 months. METHODS: Patients who underwent UAE from January 1, 1999, to July 31, 2000, for the treatment of symptomatic leiomyomas were included in the study. Transvaginal sonography was performed before and at 3, 6, and 12 months after UAE. Patients graded the severity of their symptoms on a scale from 1 to 5, with 1 being the least and 5 the most severe, before and at 12 months after the procedure. The Wilcoxon rank-sum test was used to determine correlations between severity of symptoms and presence of the white snake sign; a p value of less than 0.05 was considered significant. RESULTS: During the study period, UAE was performed in 19 patients with a mean age of 41 years (range, 32-48 years). UAE was technically successful in all patients. Eighteen patients (95%) reported symptomatic improvement at 12 months: 8 patients (42%) by 4 severity-scale points, 5(26%) by 3 points, and 5 (26%) by 2 points. The 1 patient who did not experience improvement had undergone a hysterectomy at 4 months after the UAE. At the 3-month follow-up, transvaginal sonography demonstrated a tortuous echogenic structure in the adnexa (the white snake sign) in all patients; the finding was still apparent in 10 patients at 6 months but in only 2 patients at 12 months. A direct correlation was found between persistence of the white snake sign and the degree of symptomatic improvement at 6 months (p=0.04) but not at 12 months (p=0.08). CONCLUSIONS: After UAE, a thrombosed uterine artery appears on transvaginal sonography as an echogenic tortuous structure in the adnexa. Persistence of this white snake sign at 6 months after UAE may suggest a more favorable symptomatic outcome.

Adult↗
PubMed2006

Prenatal sex ratios and expression of sexually dimorphic traits in three snake species.

Variation in intrauterine exposure to hormones associated with variation in the sex of litter mates has well-established and far-reaching effects on sexual development in some mammals. Research on this phenomenon in reptiles is scant, but suggests that lizards may follow the mammalian model whereas snakes may be affected differently. We examined sex-specific expression of four sexually dimorphic traits (tail length, head length, ventral scale count, swimming speed) in three species of snakes (Nerodia sipedon, Thamnophis sirtalis, T. sauritus) relative to litter sex ratios. We found little evidence that traits in either sex were masculinized or feminized in response to variation in litter sex ratio. The one significant result appeared best explained as a statistical artifact attributable to a single litter. Our results indicate that snakes are different from the one lizard studied to date. Unlike previous suggestions that prenatal hormonal mechanisms operate differently in snakes and lizards, however, the difference appears to be that development of sexually dimorphic traits in lizards is affected by litter sex ratios whereas in snakes it is not.

Animals↗
PubMed1993

Developmental changes in cytochrome oxidase histochemistry in the main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis spp.).

Developmental studies examining the changes in oxidative metabolic activity are useful for understanding how and if the vomeronasal and olfactory systems respond to stimulation during embryogenesis. Garter snakes are good candidates for examining the potential functionality of the vomeronasal system in utero. In adult garter snakes, the vomeronasal system mediates many behaviors. Neonatal garter snakes exhibit these same behaviors, and the vomeronasal system has been shown to mediate feeding behavior in neonates. Using cytochrome oxidase histochemistry, we examined changes in the oxidative metabolic activity of main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis sirtalis and T. s. parietalis). Cytochrome oxidase staining is greater in the accessory olfactory bulb than in the main olfactory bulb of embryonic garter snakes. However, neonates show no differences in the staining of the accessory and main olfactory bulbs, suggesting a change in the stimulation of the main olfactory bulb after birth. This is the first report of cytochrome oxidase histochemistry in reptiles and in the vomeronasal system of embryonic vertebrates.

Aging↗
PubMed1999

Spatial learning of an escape task by young corn snakes, Elaphe guttata guttata.

Spatial learning is critical to most animals for many behaviours necessary to survival. In vertebrates, most studies on spatial learning and memory have been conducted in mammalian and avian species with few studies on reptiles. We examined spatial learning in the corn snake, Elaphe guttata guttata by training 17 young snakes to find the one open shelter in an eight-hole arena, where the entrance was not visible from the arena surface. Over a 16-trial, 4-day training period, snakes showed (1) a significant decrease in the mean latency to the goal, (2) a significant decrease in the mean total distance travelled, (3) a significant increase in the percentage of the total distance travelled in the quadrant containing the goal, and (4) a significant increase in movement in the goal quadrant above chance. Although no differences were found in the number of errors made over the training period, snakes made fewer errors on all days than expected by chance. This study shows that snakes can learn rapidly a spatial-escape task that is relevant behaviourally and suggests that entering a shelter reinforces this learning. Mechanisms of orientation for the task described are discussed. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

Cardiovascular responses of semi-arboreal snakes to chronic, intermittent hypergravity.

Cardiovascular functions were studied in semi-arboreal rat snakes (Elaphe obsoleta) following long-term, intermittent exposure to +1.5 Gz (head-to-tail acceleration) on a centrifuge. Snakes were held in a nearly straight position within horizontal plastic tubes during periods of centrifugation. Centrifugal acceleration, therefore, subjected snakes to a linear force gradient with the maximal force being experienced at the tail. Compared to non-centrifuged controls, Gz-acclimated snakes showed greater increases of heart rate during head-up tilt or acceleration, greater sensitivity of arterial pressure to circulating catecholamines, higher blood levels of corticosterone, and higher blood ratios of prostaglandin F 2 alpha/prostaglandin E2. Cardiovascular tolerance to increased gravity during graded Gz acceleration was measured as the maximum (caudal) acceleration force at which carotid arterial blood flow became null. When such tolerances were adjusted for effects of body size and other continuous variables incorporated into an analysis of covariance, the difference between the adjusted mean values of control and acclimated snakes (2.37 and 2.84 Gz, respectively) corresponded closely to the 0.5 G difference between the acclimation G (1.5) and Earth gravity (1.0). As in other vertebrates, cardiovascular tolerance to Gz stress tended to be increased by acclimation, short body length, high arterial pressure, and comparatively large blood volume. Voluntary body movements were important for promoting carotid blood flow at the higher levels of Gz stress.

Adaptation, Physiological↗
PubMed1992

The distribution and colocalization of neuropeptides in perivascular nerves innervating the large arteries and veins of the snake, Elaphe obsoleta.

Single- and dual-labelling immunohistochemistry were used to determine the distribution and coexistence of neuropeptides in perivascular nerves of the large arteries and veins of the snake, Elaphe obsoleta, using antibodies for vasoactive intestinal polypeptide, substance P, calcitonin gene-related peptide, neuropeptide Y, galanin, somatostatin, and leu-enkephalin. Blood vessels were sampled from four regions along the body of the snake: region 1, arteries and veins anterior to the heart; region 2, central vasculature 5 cm anterior and 10 cm posterior to the heart; region 3, arteries and veins in a 30-cm region posterior to the liver; and region 4, dorsal aorta and renal arteries, renal and intestinal veins, 5-30 cm cephalad of the vent. A moderate to dense distribution of vasoactive intestinal polypeptide-like immunoreactive fibres was found in most arteries and veins of regions 1-3, but fibres were absent from the vessels of region 4. The majority of vasoactive intestinal polypeptide-like immunoreactive fibres contained colocalized substance P-like immunoreactivity, and these fibres were unaffected by either capsaicin or 6-hydroxydopamine (6-OHDA) pretreatment. In the anterior section of the snake, the vagal trunks contained many cell bodies with colocalized vasoactive intestinal polypeptide and substance P-like immunoreactivity. It is suggested that the vasoactive intestinal polypeptide/substance P-like immunoreactive cell bodies and fibres are parasympathetic postganglionic nerves. Neuropeptide Y-like immunoreactive fibres were observed in all arteries and veins, being most dense in regions 3 and 4. The majority of these fibres also contained colocalized galanin-like immunoreactivity, and were absent in tissues from 6-OHDA pretreated snakes, suggesting that neuropeptide Y and galanin are colocalized in adrenergic nerves. A small number of neuropeptide Y-like immunoreactive fibres contained vasoactive intestinal polypeptide but not galanin, and were unaffected by 6-OHDA treatment. All calcitonin gene-related peptide-like immunoreactive fibres contained colocalized substance P-like immunoreactivity, and these fibres were observed in all vessels, being particularly dense in the carotid artery and jugular veins. All calcitonin gene-related peptide/substance P-like immunoreactive fibres appeared damaged after capsaicin treatment suggesting they represent fibres from afferent sensory neurons. A sparse plexus of somatostatin-like immunoreactive fibres was observed in the vessels only from region 4. No enkephalin-like immunoreactive fibres were found in any blood vessels from any region. This study provides morphological evidence to suggest that there is considerable functional specialization within the components of the rat snake peripheral autonomic system controlling the circulation, in particular the regulation of venous capacitance.

Adrenergic Fibers↗
PubMed2005

Phylogeography of Australia's king brown snake (Pseudechis australis) reveals Pliocene divergence and Pleistocene dispersal of a top predator.

King brown snakes or mulga snakes (Pseudechis australis) are the largest and among the most dangerous and wide-ranging venomous snakes in Australia and New Guinea. They occur in diverse habitats, are important predators, and exhibit considerable morphological variation. We infer the relationships and historical biogeography of P. australis based on phylogenetic analysis of 1,249 base pairs from the mitochondrial cytochrome b, NADH dehydrogenase subunit 4 and three adjacent tRNA genes using Bayesian, maximum-likelihood, and maximum-parsimony methods. All methods reveal deep phylogenetic structure with four strongly supported clades comprising snakes from New Guinea (I), localities all over Australia (II), the Kimberleys of Western Australia (III), and north-central Australia (IV), suggesting a much more ancient radiation than previously believed. This conclusion is robust to different molecular clock estimations indicating divergence in Pliocene or Late Miocene, after landbridge dispersal to New Guinea had occurred. While members of clades I, III and IV are medium-sized, slender snakes, those of clade II attain large sizes and a robust build, rendering them top predators in their ecosystems. Genetic differentiation within clade II is low and haplotype distribution largely incongruent with geography or colour morphs, suggesting Pleistocene dispersal and recent ecomorph evolution. Significant haplotype diversity exists in clades III and IV, implying that clade IV comprises two species. Members of clade II are broadly sympatric with members of both northern Australian clades. Thus, our data support the recognition of at least five species from within P. australis (auct.) under various criteria. We discuss biogeographical, ecological and medical implications of our findings.

Animals↗
PubMed2004

Cobra ( Naja spp. ) nicotinic acetylcholine receptor exhibits resistance to Erabu sea snake ( Laticauda semifasciata) short-chain alpha-neurotoxin.

Snake alpha-neutotoxins of Elapidae venoms are grouped into two structural classes, short-chain and long-chain alpha-neutotoxins. While these two classes share many chemical and biological characteristics, there are also distinct dissimilarities between them, including their binding site on the nicotinic acetylcholine receptor (nAChR), specificity among species of Chordata, and the associated pharmacological effects. In the present study we test the hypothesis that structural motifs that evolved to confer natural resistance against conspecific long-chain alpha-neurotoxins in Elapidae snakes also interfere with the biological action of short-chain alpha-neurotoxins. We expressed functional nAChRs that contains segments or single residues of the Elapidae nAChR ligand binding domain and tested the effect of short-chain alpha-neurotoxin erabutoxin-a (ETX-a) from the Erabu sea snake Laticauda semifasciata on the acetylcholine-induced currents as measured by two-microelectrode voltage clamp. Our results show that the Elapidae nAChR alpha subunit segment T(154)-L(208) ligand binding domain has an inhibitory effect on the pharmacological action of ETX-a. This effect is primarily attributed to the presence of glycosylation at position N(189). If the glycosylation is removed from the T(154)-L(208) segment, the nAChR will be inhibited, however, to a lesser extent than seen in the mouse. This effect correlates with the variations in alpha-neurotoxin sensitivity of different species and, importantly, reflects the evolutionary conservation of the binding site on the nAChR polypeptide backbone per se. Phylogenetic analysis of alpha-neurotoxin resistance suggests that alpha-neurotoxin-resistant nAChR evolved first, which permitted the evolution of snake venom alpha-neurotoxins. A model describing alpha-neurotoxin resistance in Elapidae snakes is presented.

Amino Acid Sequence↗
PubMed1991

Immunological relationships between the subunits of textilotoxin and rabbit antisera raised against textilotoxin and some snake venoms.

The binding of textilotoxin and its subunits A, B, C and D to polyclonal rabbit antisera directed against textilotoxin, Australian common brown snake (Pseudonaja textilis) and tiger snake (Notechis scutatus scutatus) venoms was studied by ELISA. Subunit D showed greatest reactivity with antisera to textilotoxin and brown snake venom. The phospholipase A2 active subunit A reacted more strongly with antisera to tiger snake venom in keeping with the high degree of homology between the amino acid sequences of subunit A and notexin from tiger snake venom. Subunit A was the only subunit lethal to mice, but at doses 1000-fold greater than for textilotoxin.

Animals↗
PubMed1993

Neutralization of tiger snake (Notechis scutatus) venom by serum from other Australian elapids.

Sera from four Australian elapids and one boidid (python) were tested for their ability to protect neonatal mice against the toxic action of tiger snake (Notechis scutatus) venom. Of the five serum samples tested, only serum from Pseudechis australis and Pseudechis porphyriacus were capable of neutralizing the tiger snake venom. In addition, neutralization was shown to be highly variable within serum taken from individual snakes of the same species (P. porphyriacus). Previously, only viperid and colubrid snakes have been shown to possess neutralizing factors against snake venoms.

Animals↗
PubMed1996

L-cystine-di-beta-naphthylamidase activity in plasma of the snake Bothrops jararaca after chronic challenges of water balance.

Plasma protein, osmolality and L-cystine-di-beta-naphthylamidase activity were measured in Bothrops jararaca snakes submitted to normal hydration, water deprivation, water loading, salt loading or argvasotocin injections. Protein and osmolality were similar for male and female snakes in all treatments. Protein content was similar in all treatments, indicating the ability of the animals to maintain fluid balance between the vascular and extravascular compartment under osmotic challenges. Osmolality was increased in water-deprived and salt-loaded and was decreased in water-loaded animals compared with normally hydrated or argvasotocin-injected snakes. Enzymatic activity differed between males and females and was higher in salt-loaded females and in arg-vasotocin-injected females and males than in water-loaded snakes. A positive linear regression between osmolality and L-cystine-di-beta-naphthylamidase was obtained for female snakes (correlation coefficient = 0.6162, P < 0.01). The data show a role of arg-vasotocin in the consistent relationship between water balance and this sex-related aminopeptidase activity.

Aminopeptidases↗
PubMed2005

Isolation and pharmacological characterisation of papuantoxin-1, a postsynaptic neurotoxin from the venom of the Papuan black snake (Pseudechis papuanus).

The Papuan black snake (Pseudechis papuanus) is found throughout the southern coastal regions of Papua New Guinea and is thought to occur in the adjacent region of Iriyan Jaya. Neurotoxicity is a major symptom of envenomation by this species. This study describes the isolation of the first neurotoxin papuantoxin-1 from the venom of P. papuanus. Papuantoxin-1 (6738Da), which accounts for approximately 5% of the whole venom, was purified to homogeneity using successive steps of RP-HPLC. The toxin (0.3-1.0 microM) caused concentration dependent inhibition of indirect twitches (0.1 Hz, 0.2 ms and supramaximal V) and inhibited the responses to nicotinic agonists in the chick biventer cervicis nerve-muscle preparation, indicating a postsynaptic mode of action. However, papuantoxin-1 displayed no signs of myotoxicity. Papuantoxin-1 displayed pseudo-irreversible antagonism of cumulative concentration-response curves to carbachol at the skeletal muscle nicotinic receptors with an estimated pA2 value of 6.9+/-0.3. CSL black snake antivenom, which is raised against the venom of the Australian black snake Pseudechis australis, appears to be effective in reversing the effects of papuantoxin-1. Thus, black snake antivenom should be considered for the treatment of the neurotoxic effects following envenomation by the Papaun black snake.

Amino Acid Sequence↗
PubMed2006

Excretion of three heavy metals in the shed skin of exposed corn snakes (Elaphe guttata).

Three heavy metals of regional environmental concern-lead, cadmium, and mercury-are frequently evaluated as part of wildlife bioaccumulation and health monitoring studies. Shed skins of snakes may represent a useful, nonlethal biomarker tissue for such determinations. In the present study, these three heavy metals were injected into thawed mice that were fed to corn snakes (Elaphe guttata) such that snakes received 2mg/kg of each metal/month. Shed skins were collected over a period of 34 weeks, and levels of the heavy metals were determined in skins by atomic absorption methods. Each heavy metal was readily detected in the shed skins, with mean levels as follows: lead 234 ppb, cadmium 806 ppb, and mercury 403 ppb. Control snakes that were fed nonmetal-injected mice produced shed skins that contained mean levels of 6, 12, and 20 ppb lead, cadmium, and mercury, respectively. These detection levels corresponded closely to expected trace metal contents of mouse chow and tap water. These results demonstrate that dietary metal exposure can be readily detected in shed snake skins, including at trace levels of exposure that may be consistent with, or below, environmental exposures.

Animals↗
PubMed2005

Toxins not neutralized by brown snake antivenom.

The Australian snakes of the genus Pseudonaja (dugite, gwardar and common brown) account for the majority of snake bite related deaths in Australia. Without antivenom treatment, the risk of mortality is significant. There is an accumulating body of evidence to suggest that the efficacy of the antivenom is limited. The current study investigates the protein constituents recognized by the antivenom using 2-DE, immuno-blot techniques and rat tracheal organ bath assays. The 2-DE profiles for all three snake venoms were similar, with major species visualized at 78-132 kDa, 32-45 kDa and 6-15 kDa. Proteins characterized by LC-MS/MS revealed a coagulant toxin ( approximately 42 kDa) and coagulant peptide ( approximately 6 kDa), as well as two PLA(2) ( approximately 14 kDa). Peptides isolated from approximately 78 kDa and 15-32 kDa protein components showed no similarity to known protein sequences. Protein recognition by the antivenom occurred predominantly for the higher molecular weight components with little recognition of 6-32 kDa MW species. The ability of antivenom to neutralize venom activity was also investigated using rat tracheal organ bath assays. The venoms of Pseudonaja affinis affinis and Pseudonaja nuchalis incited a sustained, significant contraction of the trachea. These contractions were attributed to PLA(2) enzymatic activity as pre-treatment with the PLA(2) inhibitor 4-BPB attenuated the venom-induced contractions. The venom of Pseudonaja textilis incited tracheal contractility through a non-PLA(2) enzymatic activity. Neither activity was attenuated by the antivenom treatment. These results represent the first proteomic investigation of the venoms from the snakes of the genus Pseudonaja, revealing a possible limitation of the brown snake antivenom in binding to the low MW protein components.

Animals↗
PubMed2003

Phylogenetic conservation of a snake venom metalloproteinase epitope recognized by a monoclonal antibody that neutralizes hemorrhagic activity.

Snake venom metalloproteinases (SVMPs) are present in large quantities in venoms of viper snakes and also in some elapids. Jararhagin is a representative of a P-III multidomain hemorrhagic SVMP present in Bothrops jararaca venom. It is comprised of a catalytic, a disintegrin-like and a cysteine-rich domain. Seven anti-jararhagin monoclonal antibodies (MAJar 1-7) were produced, of which six reacted with the disintegrin domain. MAJar 3 recognized an epitope present at the C-terminal part of the disintegrin-like domain, and neutralized jararhagin-induced hemorrhage. In this study, we evaluated the reactivity of these monoclonal antibodies with venoms from 27 species of snakes belonging to different families. MAJar 3 recognized most of the hemorrhagic venoms. By ELISA, MAJar 3 reacted strongly with venoms from Viperidae family and weakly with Colubridae and Elapidae venoms. This recognition pattern was due to bands between 50 and 80 kDa, corresponding to P-III SVMPs. This antibody preferentially neutralized the hemorrhage induced by venoms of Bothrops snakes. This fact suggests that the epitope recognized by MAJar 3 is present in other metalloproteinases throughout snake phylogeny. However, slight structural differences in the epitope may result in insufficient affinity for neutralization of biological activities.

Amino Acid Sequence↗