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PubMed1980

Epidemiological aspects of snake bites on a Liberian rubber plantation.

During a one-year period 95 patients with a history of snake bite were admitted to the hospital of a Liberian rubber plantation. The population at risk included the field workers (tappers and slashers) with an incidence of 4.2 symptomatic snake bites per thousand per year. The incidence of symptomatic bites was 1.7 per thousand in the group of non-field employees and 0.4 per thousand per year in the group of non-employees. The temporary disability was between 3 and 5 days, and the loss of workings days due to snake bites was one day per 10,000 working days on the plantation. Among the 95 patients 27 did not show any symptoms of envenoming except occasional fang marks. 64 patients developed cytotoxic symptoms alone. In this group, the night adder (Causus maculatus) was the main responsible snake. 4 patients showed signs of systemic envenoming. Two were haematological and two were neurological in nature and caused by Bitis species and Naja species, respectively. No fatalities were noted. A definite maximum of snake bites was observed during October and November which corresponds to the transition from rainy to dry season.

Animals↗
PubMedDate not supplied

[Snakes endemic to plantations of the Ivory Coast].

Authors describe the taxonomic composition of snake population in some plantations of Ivory Coast. In these areas, hazards of snake bites has been studied. They show that in extensive farming ecological conditions are strongly changed inducing modifications into the snake populations. In rustic farming area ecological conditions do not change with those of the brush or village surrounding. Snake bites in some extensive farming are ten times more frequent than in village or rustic plantations around them. This is linked to the snakes and farmers densities which are different in each plantation. Lethal effect is weak as in envenomations declared during any other activities.

Agricultural Workers' Diseases↗
PubMed1983

The electric fence for preventing invasion of Trimeresurus flavoviridis, Habu, the venomous snake.

For the purpose of preventing invasion of Trimeresurus flavoviridis, Habu, the venomous snake, the effect of an electric fence made of hollow tile blocks or polyethylene net was examined in 3 villages on Amamioshima and Tokunoshima islands in the southernmost area of Japan. The electric pulses were supplied by a pulse maker at 0.75 sec. intervals with 480 mA, 0.13 m coulombs at a load of 500 ohms and estimated peak of 8 to 10 kV. The anode from a pulse maker was connected to a stainless steel plate or a metal string woven in a vinyl rope on the fence and the cathode was grounded. The power to the pulse maker was generated by silicon solar cells, stored in a car battery and regulated by an electric eye switch to activate it at night. The necessary height of the fence to prevent Habu from slithering over the fence was experimentally determined to be 60 cm. In 3 villages, 6.75 ha were enclosed with 1000 m fence, 13.7 ha with 2100 m and 23.8 ha with 2500 m, respectively. The effect of the electric fence was remarkable as determined by the annual monitoring of the number of snakes sighted by people and the captivity rate in box traps inside the fence. The number of snakes found annually in Tean Village was 10 before construction and 5, 4, 5 after construction; 119 before construction 55, 20, 20 after construction at Tete; and 109 and 82 before construction and 15 and 11 after construction at Todoroki. The snakes were observed to aggregate outside the fence. The net barrier could be constructed at any topographical conditions with less expense. The effect was further pronounced when snakes were removed by box trap and other methods from inside the fenced area.

Animals↗
PubMed1980

Clinical laboratory: enzyme immunoassay for the rapid clinical identification of snake venom.

The treatment of snakebite could be simplified if the identity of the offending snake was more frequently known. A positive identification, which allows the use of a specific monovalent antivenom, probably occurs in less than 20% of cases. Recently published methods of venom detection (RIA and ELISA) take at least three hours to complete. We have developed a sandwich enzyme immunoassay (EIA) which is capable of detecting 0.5 ng of crude snake venom in about 90 minutes or 2 ng of crude venom in about 30 minutes. This substantial reduction in incubation times, while still retaining the sensitivity required, was due to the use of protein A purified rabbit IgG antivenom from hyperimmune serum and the enzyme horseradish peroxidase (HRPO). A rapid identification of the offending snake by this method may reduce the use of large-volume polyvent antivenoms, thus avoiding the clinical and economic disadvantages of such preparations. Other advantages would be an increased understanding of the clinical syndrome produced by the individual species of snake, and accumulation of data about the incidence of envenoming attributed to specific snakes.

Animals↗
PubMed1994

Bite of a sea snake (Hydrophis spiralis): a case report from Sri Lanka.

A rare case of sea-snake bite resulting in envenoming is reported. Comparison is made with clinical features of sea-snake envenoming as described in the literature. Some of the unusual features observed in our patient were the occurrence of pain at the site of the bite, regional lymph node enlargement and absence of muscle pain and tenderness. Polyvalent land-snake antivenom was used in the management of this patient since specific antivenom against sea-snake envenoming is not available in Sri Lanka. There was some improvement in neurological signs after the start of antivenom treatment. This is the first authenticated case of sea-snake envenoming in Sri Lanka.

Adult↗
PubMed1994

When a snake bites.

Primary care physicians may be required to treat snake-bitten patients and must differentiate between venomous and nonvenomous snakes. The chief distinguishing characteristics of venomous snakes are fangs and a single row of subcaudal anal plates. The physiologic effects of snake venom are on the cardiovascular, hematologic, and neurovascular systems. The snake-bitten patient first needs supportive treatment and stabilization. Then, the physician must establish whether envenomation has occurred, grade it, and monitor edema around the bite. Local treatment, broad-spectrum antibiotics, and tetanus prophylaxis should be used for all envenomation grades. The decision to administer antivenin therapy should be made on clinical grounds and the envenomation grade. Its use, however, can lead to anaphylaxis and anticomplement reactions.

Anti-Bacterial Agents↗
PubMed2006

Function of snake mobbing in spectral tarsiers.

Numerous species are known for their tendency to approach and confront their predators as a group. This behavior is known as mobbing. Snakes seem to be one of the more consistent recipients of this type of predator-directed behavior. This paper explores individual differences (sex and age) in the mobbing behavior of the spectral tarsier toward live and model snakes. This study was conducted at Tangkoko Nature Reserve (Sulawesi, Indonesia) during 2003-2004. During this research, 11 natural mobbing events and 31 artificially induced mobbing events were observed. The mean number of individuals at a mobbing was 5.7. The duration of mobbing events was strongly correlated with the number of assembled mobbers. Adults were more likely than other age classes to participate in mobbings. Males were more likely than females to participate in mobbings. Mobbing groups often contained more than one adult male, despite the fact that no spectral tarsier group contains more than one adult male. No difference in body size between extragroup males and resident males was observed, refuting the "attract the mightier" hypothesis. The number of mobbers did not affect whether the tarsier or the snake retreated first, countering the "move-on" hypothesis. The "perception advertisement" hypothesis was tentatively supported, in that live snakes were rarely seen in the area following mobbing calls, in comparison to when tarsiers either ignored the snake or alarm call.

Activity Cycles↗
PubMed1990

Anatomy of the pancreas and Langerhans islets in snakes and lizards.

The pancreas of snakes (18 species) was comparatively examined and classified into five major types, based on structure of the lobes and ducts, spatial relationships with the spleen and the gall bladder, and the disposition of islet cells. These types trend toward fusion of the pancreatic lobes and compaction of the pancreas--a progression that coincides with the phylogeny of the snakes. The more primitive pancreas of lizards (17 species) also was surveyed; that of Varanus is of special interest because its structure is intermediate between the extended, tri-lobate pancreas of lizards and the compact pancreas of snakes and may represent a transitional link in the evolution of this organ. Islet tissue is always confined to the dorsal lobe and is concentrated in its distal region adjacent to the spleen. In primitive snakes and in Varanus, a large islet mass is sequestered within a distinct juxtasplenic "islet body" distanced from the dorsal lobe and connected to it by a slender stalk. In some of the most advanced snake species, numerous islets of endocrine cells are found within the spleen. The occurrence and formation of these intrasplenic islets is described in detail. The anatomic "affinity" between spleen and the islet region of the pancreas is discussed. A hypothesis for the development of the pancreas from embryonal placodes on the mid-gut is presented; it proposes that the exocrine and the endocrine components derive from different progenitor cells, and that the endocrine progenitors are located in the center of the dorsal placode. The hypothesis combines embryological and evolutionary views about the origin of the pancreas, and offers a rationale for differences in its structure and in the disposition of the islets.

Animals↗
PubMed2005

Immunolocalization and characterization of cornification proteins in snake epidermis.

Little is known about specific proteins involved in keratinization of the epidermis of snakes, which is composed of alternating beta- and alpha-keratin layers. Using immunological techniques (immunocytochemistry and immunoblotting), the present study reports the presence in snake epidermis of proteins with epitopes that cross-react with certain mammalian cornification proteins (loricrin, filaggrin, sciellin, transglutaminase) and chick beta-keratin. alpha-keratins were found in all epidermal layers except in the hard beta- and alpha-layers. beta-keratins were exclusively present in the oberhautchen and beta-layer. After extraction and electrophoresis, alpha-keratins of 40-67 kDa in molecular weights were found. Loricrin-like proteins recorded molecular weights of 33, 50, and 58 kDa; sciellin, 55 and 62 kDa; filaggrin-like, 52 and 65 kDa; and transglutaminase, 45, 50, and 56 kDa. These results suggest that alpha-layers of snake epidermis utilize proteins with common epitopes to those present during cornification of mammalian epidermis. The beta-keratin antibody on extracts from whole snake epidermis showed a strong cross-reactive band at 13-16 kDa. No cross-reactivity was seen using an antibody against feather beta-keratin, indicating absence of a common epitope between snake and feather keratins.

Animals↗
PubMed2003

Proteomics of snake venoms from Elapidae and Viperidae families by multidimensional chromatographic methods.

Snake venoms contain a large number of biologically active substances and the venom components are very useful for pharmaceutical applications. Our goal is to separate and identify components of snake venoms in ten snake species from the Elapidae and Viperidae families using multidimensional chromatographic methods. The multidimensional chromatographic methods include reversed-phase high-performance liquid chromatography (RP-HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), lab-on-a-chip, two-dimensional electrophoresis (2-DE), and mass spectrometry. The venoms of eight snake species demonstrated major differences in hydrophobicity, molecular weight separations, and 2-DE protein distribution patterns. The 2-DE images showed major differences between families, within each family and even between the same species. Venoms of the Elapidae family showed many basic proteins with a wide range of molecular weights, while venoms of the Viperidae family showed wide ranges of pI and molecular weights, especially for Trimeresurus sp. The multidimensional chromatographic methods revealed specific differences in venom proteins intra-species as well as between species and families. We have isolated and identified proteins that may be unique for each species for further studies in the proteome of snake venoms and their potentially use in the pharmaceutical applications.

Animals↗
PubMed2006

The use of therapeutic plasmapheresis in the treatment of poisoned and snake bite victims: an academic emergency department's experiences.

The objective of this study is to describe the clinical status, procedural interventions, and outcomes of critically ill patients with poisoning and snake bite injuries presenting to a tertiary-care emergency department for treatment with therapeutic plasmapheresis. Records of 20 patients who presented to our academic emergency department over a 2-year period and who underwent plasmapheresis for poisoning or snake bite were retrospectively reviewed. Plasmapheresis was performed using centrifugation technology via an intravenous antecubital venous or subclavian vein catheter access. Human albumin or fresh frozen plasma were used as replacement fluids. Data extracted from the patient record included demographic data, clinical status, and outcome measures. Sixteen patients underwent plasmapheresis because of toxicity from snake bite. Three patients were treated for drug poisoning (phenytoin, theophylline, bipyridene HCl) and one patient for mushroom poisoning. Haematologic parameters such as platelet count, PT, and INR resolved rapidly in victims of snake bite injuries after treatment with plasmapheresis. Loss of limbs did not occur in these cases. Seven patients required admission to the intensive care unit. One patient with mushroom poisoning died. Mean length of hospital stay was 14.3 days (range 3-28 days) for all cases. Plasmapheresis was a clinically effective and safe approach in the treatment of snake bite envenomation and other drug poisoning victims especially in the management of hematologic problems and in limb preservation/salvage strategies. In addition to established conventional therapies, emergency physicians should consider plasmapheresis among the therapeutic options in treatment strategies for selected toxicologic emergencies.

Adolescent↗
PubMed2005

Influence of body reserves and eye opacity on foraging behaviours of tiger snakes.

Physiological states such as reproductive stage, parasite load, body condition, and environmental conditions, influence behaviours in complex ways. According to the Clark's asset-protection principle (Clark, 1994. Behav Ecol 5:159-170), individuals in good body condition take fewer predation risks than conspecifics in lesser condition. In many ectotherms, foraging, digestion, and moulting require an elevation of the metabolism achieved through intensive basking, thereby increasing the risk of being detected by predators. Using four experimental groups of snakes, we showed that two independent physiological states, (1) the presence of prey in the stomach and (2) eye opacity associated with moulting, increase predator vulnerability. In a parallel experiment, two groups of snakes were maintained on contrasting diets (high food intake vs. low food intake) for 6 months. Apart from sloughing periods, most individuals (89%) accepted their meal irrespective of food treatment. Consequently, well-fed snakes exhibited higher body condition (one third physiological state) relative to less-fed individuals. During sloughing events, however, well-fed individuals often refused (78%) to eat while the less-fed individuals readily accepted (86%) their meal despite eye opacity. Individuals with less body reserves accepted the cumulative risks owing to eye opacity and stomach fullness. By contrast, well-fed snakes remained more "prudent" (i.e., exhibited behaviours that depended on their internal state). Our results show that snakes can adjust their foraging "decision" by combining different physiological informations.

Analysis of Variance↗
PubMed2001

New vascular system in reptiles: anatomy and postural hemodynamics of the vertebral venous plexus in snakes.

Using corrosion casting, we demonstrate and describe a new vascular system--the vertebral venous plexus--in eight snake species representing three families. The plexus consists of a network of spinal veins coursing within and around the vertebral column and was previously documented only in mammals. The spinal veins of snakes originate anteriorly from the posterior cerebral veins and form a lozenge-shaped plexus that extends to the tip of the tail. Numerous anastomoses connect the plexus with the caval and portal veins along the length of the vertebral column. We also reveal a posture-induced differential flow between the plexus and the jugular veins in two snake species with arboreal proclivities. When these snakes are horizontal, the jugulars are observed fluoroscopically to be the primary route for cephalic drainage and the plexus is inactive. However, head-up tilting induces partial jugular collapse and shunting of cephalic efflux into the plexus. This postural discrepancy is caused by structural differences in the two venous systems. The compliant jugular veins are incapable of sustaining the negative intraluminal pressures induced by upright posture. The plexus, however, with the structural support of the surrounding bone, remains patent and provides a low-pressure route for venous return. Interactions with the cerebrospinal fluid both allow and enhance the role of the plexus, driving perfusion and compensating for a posture-induced drop in arterial pressure. The vertebral venous plexus is thus an important and overlooked element in the maintenance of cerebral blood supply in climbing snakes and other upright animals.

Animals↗
PubMed2003

Analysis of Colubroidea snake venoms by liquid chromatography with mass spectrometry: evolutionary and toxinological implications.

The evolution of the venomous function of snakes and the diversification of the toxins has been of tremendous research interest and considerable debate. It has become recently evident that the evolution of the toxins in the advanced snakes (Colubroidea) predated the evolution of the advanced, front-fanged delivery mechanisms. Historically, the venoms of snakes lacking front-fanged venom-delivery systems (conventionally grouped into the paraphyletic family Colubridae) have been largely neglected. In this study we used liquid chromatography with mass spectrometry (LC/MS) to analyze a large number of venoms from a wide array of species representing the major advanced snake clades Atractaspididae, Colubrinae, Elapidae, Homalopsinae, Natricinae, Psammophiinae, Pseudoxyrhophiinae, Xenodontinae, and Viperidae. We also present the first sequences of toxins from Azemiops feae as well as additional toxin sequences from the Colubrinae. The large body of data on molecular masses and retention times thus assembled demonstrates a hitherto unsuspected diversity of toxins in all lineages, having implications ranging from clinical management of envenomings to venom evolution to the use of isolated toxins as leads for drug design and development. Although definitive assignment of a toxin to a protein family can only be done through demonstrated structural studies such as N-terminal sequencing, the molecular mass data complemented by LC retention information, presented here, do permit formulation of reasonable hypotheses concerning snake venom evolution and potential clinical effects to a degree not possible till now, and some hypotheses of this kind are proposed here. The data will also be useful in biodiscovery.

Animals↗
PubMed1993

Influence of photoperiod and temperature on serum melatonin in the diamondback water snake, Nerodia rhombifera.

Serum melatonin concentrations in the diamondback water snake, Nerodia rhombifera, were measured with a radioimmunoassay to determine the influence of photoperiod and temperature on melatonin levels. A diel cycle of serum melatonin, with elevated concentrations during scotophase, occurred in snakes acclimatized for 2 weeks to a 12L:12D photoperiod and 25 degrees. This cycle persisted in snakes acclimatized to a reverse photoperiod, with a longer duration of elevated scotophase levels. In snakes acclimatized to a normal 12L:12D photoperiod and 10 degrees, photophase serum melatonin concentrations were lower than at 25 degrees, and there was no increase during scotophase. Snakes acclimatized to a normal 12L:12D photoperiod and 35 degrees had lower serum melatonin levels than those at 25 degrees, but this difference was not statistically significant. Photoperiod and temperature interact to influence serum melatonin in N. rhombifera, with photoperiod affecting the phase and temperature affecting the amplitude of the diel melatonin cycle.

Animals↗
PubMed1985

Maintenance of blood volume in snakes: transcapillary shifts of extravascular fluids during acute hemorrhage.

Tracer dilution analysis (D2O, 51Cr, and NaS14CN) was used to investigate the steady-state compartmentation of body fluids and the extent of fluid transfer from extravascular to vascular spaces during hemorrhage-induced hypovolemia in two species of snakes, Elaphe obsoleta and Crotalus viridis. Fluid spaces of the two species are not significantly different (means, blood volume 6.1, 5.4; extracellular fluid 42.2, 41.9; total body water 77.2, 77.2% body mass, respectively), but values for extracellular fluid exceed those reported for other reptiles. Both species of snake withstand graded hemorrhage where 4% of the initial blood volume is withdrawn every 10 min until the cumulative deficit is 32%. Some snakes are able to maintain their initial blood volume throughout hemorrhage, while others restore 90% of deficits within 2 h after hemorrhage ceases. Typically, 50-60% of the hemorrhaged deficit is transferred from the interstitium to the circulation throughout hemorrhage (Fig. 2). The source of fluid entering the vascular space is entirely extracellular during hemorrhage, the blood within 2 h after hemorrhage ceases. Snakes are able to maintain arterial pressure during these experiments (Fig. 3). The ability of snakes to maintain hemodynamic stability despite substantial losses of blood can be explained in terms of a large interstitial fluid volume that may shift rapidly to the vascular space. Shifts in the opposite direction also occur in response to hemodynamic factors, implying a low resistance to fluid movement across the capillary wall.

Animals↗
PubMed1985

Contractile response of the isolated dorsal aorta of the snake to angiotensin II and norepinephrine.

Vasopressor action is a phylogenetically old function of angiotensin (ANG) II. The action can be ascribed to both direct activation of vascular ANG II receptors and through catecholamine release. In the Rat snake, Ptyas korros, the possible presence of common adrenergic-ANG receptors and their involvement in this action have been proposed. In order to elucidate the vasopressor mechanism of ANG II in the snake, and to test the presence of common adrenergic-ANG receptors, the contractile response of isolated snake dorsal aorta to [Val5]ANG II and norepinephrine (NE) was studied using the cobra, Naja naja and the Rat snake, Ptyas korros. Both ANG II (3 X 10(-11) to 10(-6) M) and NE (10(-8) to 10(-5) M) produced a dose-dependent increase in tension in the aortic strips of Naja, which were more sensitive to ANG II. Phenotolamine, an alpha-adrenergic antagonist, competitively inhibited NE without altering the response to ANG II. [Sar1, Ala8]ANG II inhibited ANG II but did not affect the response to NE. A similar dose-dependent increase in tension in the aortic strips of Ptyas was seen with NE (10(-8) to 10(-5) M) but these strips did not respond to ANG II. These results suggest that functionally separate receptors for ANG II and NE exist in the dorsal aorta of the cobra and that local liberation of catecholamines from the adrenergic nerve terminals do not play a role in the expression of ANG II action. There also exist differences in the nature of ANG II action/receptors among different species of snakes and different vascular beds in the same species.

Angiotensin II↗
PubMed1988

Gonadotropin-releasing hormone from brains of reptiles: turtles (Pseudemys scripta) and snakes (Thamnophis sirtalis parietalis).

Gonadotropin-releasing hormone (GnRH)-like peptides were present in whole brain extracts of turtle (Pseudemys scripta) and snake (Thamnophis sirtalis parietalis) with higher content and concentration in the turtle brain. The peptides were identified by cross-reactivity profiles with four GnRH antisera and by retention times on reverse-phase high-pressure liquid chromatography (HPLC) compared with synthetic GnRH standards. Turtle brain extracts contained two HPLC peaks that cross-reacted with GnRH antisera; these peaks eluted from the HPLC in the same positions as chicken I and II GnRH. Snake brain extracts contained only one major HPLC peak (and two minor peaks in some brains) that cross-reacted with anti-GnRH sera; the major peak eluted with the same retention time as chicken I GnRH. Mammalian, salmon, and lamprey GnRH-like peptides were not detected. In extracts from both turtle and snake brains, the cross-reactivity profile of the HPLC peaks compared with those of synthetic chicken I and II GnRH showed a similar order of sensitivity with four antisera. It is likely that chicken I and II GnRH-like peptides were present in ancestral reptiles prior to the evolution of the three living reptilian subclasses of Anapsida (turtle), Lepidosauria (snake and lizard), and Archosauria (alligator). This assertion is based on the present demonstration and work by others showing that chicken I and II GnRH-like peptides are in turtle and alligator, chicken I is in snake, and chicken II is in lizard.

Animals↗