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At least 811 records · Page 45Linked to original sources
PubMed1991

The epidemiology of snake bite presenting to British Military Hospital Dharan during 1989.

Fifty-eight cases of snake bite seen at the British Military Hospital, Dharan, Nepal during 1989 were studied prospectively. Data is presented on the epidemiology and outcome of snake bite in this area of lowland Nepal with details of the age and sex of patients, date and time of bite, delay in arrival at hospital, use of tourniquets, circumstances of the bite, and snake identification. Neurotoxicity due to envenomation was recorded in 11 patients. No case of coagulopathy was recorded. The overall case fatality was 5.2% but mortality amongst those exhibiting signs of neurotoxicity was 27.3%.

Adolescent↗
PubMed1998

Myasthenic syndrome of snake envenomation: a clinical and neurophysiological study.

In this prospective study, 65 consecutive patients with neurological manifestations after snake envenomation, were examined in order to describe the natural history of the reversible nature of muscle weakness. Snake envenoming led to a completely reversible muscle paralysis involving the external ocular muscles with sparing of the pupils, muscles of mastication, facial muscles, palatal muscles, neck and proximal limb muscles. The deep tendon reflexes were preserved with no sensory abnormalities. The muscular weakness usually set in within an hour of envenomation and lasted up to 10 days, with fatigability lasting for 12 days. Respiratory muscle paralysis led to ventilatory failure needing ventilation in severely envenomed patients. Motor and sensory nerve conduction were normal with normal resting compound motor action potentials on electromyography. Repetitive nerve stimulation gave rise to a decremental response during high frequency stimulation. The edrophonium test gave negative results. These manifestations are due to abnormalities of neuromuscular transmission and are not typical of myasthenia gravis. As the exact pathophysiology of venom-related neurotoxicity is not known, it is suggested that the neurological manifestations of snake envenoming be designated a myasthenic syndrome. Further studies to isolate the neurotoxin and its mechanism and exact site of blocking at the neuromuscular junction would pave the way for the development of a novel long-acting neuromuscular blocking agent.

Action Potentials↗
PubMed1989

Snake venom components and their cross-reactivity: a review.

Snake venoms are complex mixtures of organic and inorganic compounds, many of which display biological activity. It has been demonstrated that antisera raised against whole venom or a single purified venom protein from one species of snake will react with proteins in the venom of other species. This cross-reactivity between species may have applications in determining snake phylogeny, but recent studies on the variation of venom components within a species make these evolutionary conclusions questionable.

Amino Acid Oxidoreductases↗
PubMed1982

Functional anatomy of the lung of the snake Pituophis melanoleucus.

The respiratory system in Pituophis melanoleucus is composed of a trachea, a single bronchial lung containing the pulmonary vasculature, and a large membranous caudal air sac. Total air volume (VL) in a 1-kg snake is 97.5 ml and varies with size (M) according to the equation VL = 0.388 M0.80 where VL is in milliliters and M is in grams. These air volumes are similar to those measured in many lizards and turtles. Relative volumes of the trachea, vascular lung, and air sac in Pituophis are about 4, 20, and 76%, respectively. The respiratory tissue is composed of a honeycomb network of capillary-bearing partitions, which collectively forms the gas exchange surface. This respiratory tissue is confined to the proximal 20% of the lung. Total respiratory surface area (SA) in a 1-kg snake is 2.00 x 10(3) cm2 and varies with size according to the equation SA = 3.03 M0.94 where SA is in square centimeters. Total SA/VL within the bronchial lung is large, being approximately 101 cm2/ml. Gradients in respiratory surface area and lung air volume are reversed so that SA/VL is highest near the cranial tip of the lung and decreases towards the air sac. Harmonic mean thickness of the air-blood barrier was found to be 0.46 +/- 10(-4) cm with the result that the anatomic diffusion factor, or ratio of respiratory surface area to mean diffusion distance, for a 1-kg snake is 0.44 x 10(8) cm. This index of diffusion capacity is very close to that reported for two lungs of a turtle.

Animals↗
PubMed1993

Antioxidant defenses in the tolerance of freezing and anoxia by garter snakes.

The garter snake Thamnophis sirtalis parietalis can readily tolerate several hours of freezing or anoxia exposure. Both stresses halt oxygen availability to tissues and to endure these stresses snakes must cope with potential oxidative stress arising as a result of the ischemic/anoxic condition followed by reperfusion of aerated blood during recovery. To determine whether antioxidant defenses are important for freezing and anoxia survival, we monitored the activities of antioxidant enzymes and the levels of glutathione (GSH and GSSG) during freezing (5 h at -2.5 degrees C) and anoxia (10 h under N2 gas at 5 degrees C) exposures in three organs (muscle, liver, and lung) of snakes. Freezing resulted in a significant rise in the activity of muscle and lung catalase (by 183 and 63%) and in muscle glutathione peroxidase (52%). Anoxia enhanced muscle and liver superoxide dismutase activities (by 59 and 118%) and also caused a 57% increase in muscle GSH levels. The increase in muscle GSH concentration in anoxia (from 0.45 to 0.71 mM) could also stimulate muscle glutathione peroxidase activity in vivo by 1.5-fold because of its low affinity for GSH (Km = 11 mM). The ratio of GSSG/GSH was not affected by experimental state in any tissue, suggesting that oxidative stress did not occur during the freezing or anoxic exposure. Rather, H2O2- and O2(-)-detoxification systems may be activated in preparation for possible oxygen free radical overgeneration during thawing or reoxygenation. Antioxidant defenses appear to be part of the adaptive machinery for reptilian tolerance of freezing and anoxia.

Adaptation, Physiological↗
PubMedDate not supplied

Multifunctional snake C-type lectins affecting platelets.

Snake venoms contain a wide range of components, many of which affect haemostasis by activation or inhibition of platelets or coagulation factors. They can be classified into groups based on structure and mode of action. One group is the snake C-type lectins, so called because of the typical folding which closely resembles that found in classical C-type lectins, such as selectins and mannose-binding proteins. Unlike the classic C-type lectins, those from snakes are generally heterodimeric with two subunits, alpha and beta. Some are multimeric heterodimers. The subunits have homologous sequences and are generally linked by a disulphide bond as well as by swapping loops. One of the first C-type lectins with a defined function was echicetin which was demonstrated to bind to platelet GPIb and block several functions of this receptor. Since then, many proteins with similar structure have been reported to act on platelet receptors or coagulation factors and several have been crystallized. These proteins were thought to be specific for a single platelet receptor or coagulation factor, i.e. they had only one receptor per heterodimer. Recent studies show that most of these C-type lectins have binding sites for more than one ligand and have complex mechanisms of action.

Animals↗
PubMed1993

Electrophysiological analysis of the nasal chemical senses in garter snakes.

Electroolfactogram and electrovomeronasogram recordings were made from garter snakes stimulated with vapor of amyl acetate, butanol and of earthworm wash. The olfactory epithelium was more sensitive than the vomeronasal epithelium to all three stimuli. Volatiles from prey washes were capable of stimulating the olfactory epithelium when delivered as airstreams. The vomeronasal epithelium was sensitive only to the air delivery of vapor of amyl acetate. Single unit recordings from the mitral cell layer of the accessory olfactory bulb of garter snakes were made in response to liquid delivery of a variety of chemical stimuli including classical odorants, amino acids and proteins derived from prey. All three classes of stimuli altered unit firing in the accessory olfactory bulb. Amyl acetate, earthworm wash, goldfish wash and non-volatile amino acids delivered as liquid stimuli to the vomeronasal epithelium produced responses in the accessory olfactory bulb that were more distinct and reliable than the electrovomeronasogram responses to airborne odorants recorded at the periphery. Both excitatory and inhibitory responses were observed in the accessory olfactory bulb of garter snakes. The direction of the response to a given stimulus differed for different neurons. Responses were frequently biphasic and could last longer than 50 seconds. Individual neurons responded to different classes of stimuli suggesting that they are broadly tuned.

Animals↗
PubMed1992

Sexual behavior and 2-deoxyglucose uptake in male red-sided garter snakes (Thamnophis sirtalis parietalis).

The [14C]2-deoxyglucose (2-DG) technique was used to study patterns of neural activity associated with the species-typical courtship behavior of male red-sided garter snakes (Thamnophis sirtalis parietalis). Males in this species court females intensely during the first month following spring emergence from their prolonged winter hibernation. Autoradiographic methods were used to measure the accumulation of radioactive label in various regions through the brains of male garter snakes that courted females, males that failed to court females, and males not exposed to females. Male garter snakes that actively courted females showed a pronounced increase in 2-DG accumulation, and therefore presumably neural activity, in the region of the anterior hypothalamus/preoptic area, relative to males that did not actively court females. Males exposed to females (regardless of whether they courted or not) showed widespread, non-specific increases in 2-DG uptake relative to males not exposed to females. The results indicate the utility of the 2-DG technique for studying complex, species-typical behaviors in vertebrates.

Animals↗
PubMed1987

Field observation of snake-mobbing in a group of saddle-back tamarins, Saguinus fuscicollis nigrifrons.

At the Rio Blanco in Northeastern Peru a group of 6 saddle-back tamarins was observed to mob two Corallus enydris snakes which were hanging from a liana. These and other observations of snake-mobbing demonstrate that callitricids exhibit a special behaviour against potential predators, which is very similar to the mobbing displays of birds and other mammals. It is suggested that the adaptive significance of snake-mobbing in tamarins lies in the cultural transmission of information about potential predators.

Aggression↗
PubMed1991

Cultural transmission of snake-mobbing in free-ranging Hanuman langurs.

A focal troop of free-ranging Hanuman langurs (Presbytis entellus) living in an open scrub forest around Jodhpur was observed mobbing poisonous snakes on two different occasions during field observations of about 4,109 h. These observations of snake-mobbing demonstrate that langurs exhibit a special behaviour against 'potentially dangerous animals' which is similar to the mobbing displays of birds, and of other primates. It is suggested that the adaptive significance of snake-mobbing among langurs lies in the 'cultural transmission' of this information. These observations further support the 'kin-selection' model.

Aggression↗
PubMed1989

Fixation of pemphigus vulgaris and foliaceus antibodies in shedding snake epidermis.

The fixation of pemphigus antibodies was revealed by indirect immunofluorescence in shedding grass snake epidermis. The antibodies of patients with pemphigus vulgaris (PV) were specifically binding to the antigenic substance which appears in the snake epidermis at the initial stage of integument change. At the peak of shedding, the fixation of PV antibodies was observed only in the upper layers of the 'old' epidermis, although the intensity of fluorescent staining was considerably reduced. At the same stage of shedding, there was marked fixation of antibodies of patients suffering from pemphigus foliaceus (PF). The specific binding of PF antibodies was noted predominantly on the cell membranes of the 'old' keratinocytes, localized in the upper layers of the epidermis. In contrast to bullous pemphigoid antibodies, PV and PF antibodies failed to fix in the skin of the snake prior to or after physiologic shedding. The data obtained suggest that pemphigus may have an atavistic origin.

Adult↗
PubMed1998

Severe multi-system failure following delayed presentation with tiger snake envenomation.

A 68 year-old-man presented some twelve hours after a presumed Tiger Snake bite with coagulopathy, paralysis and muscle necrosis. He suffered multi-system failure requiring prolonged ventilation, haemodialysis and supportive care, to be discharged after 26 days. Delays to antivenom therapy after tiger snake envenomation can result in significant morbidity. Australian snakes are the most venomous in the world.

Aged↗
PubMed2001

Novel approach to improve permeation of ondansetron across shed snake skin as a model membrane.

The purpose of this study was to investigate the feasibility of transdermal drug delivery of ondansetron, an antagonist of the 5-HT3 receptor, used for the treatment of chemotherapy-induced emesis. The permeability of ondansetron from an aqueous suspension through shed snake skin as a model membrane was very low and in order to improve it, several enhancers were tested. Ethanol increased the flux at a concentration of 40% or more. The solubility of ondansetron also increased as the ethanol concentration increased. The permeability coefficient increased after pretreatment of the shed snake skin with Azone, oleic acid or lauryl alcohol. Further improvement of the permeability was observed when ethanol was combined with other enhancers and was maximum for the combination of ethanol and oleic acid. Oleic acid dramatically increased the partition of ondansetron to n-hexane and shed snake skin. Oleic acid may enhance the permeation of ondansetron in two ways: by a direct effect on the stratum corneum or via counterion formation of an ion-pair. The maximum flux obtained from the combination of ethanol and other enhancers seems to be high enough to obtain a therapeutic effect.

Administration, Cutaneous↗
PubMed1984

Calcium metabolism in embryos of the oviparous snake Coluber constrictor.

Total calcium in embryos of an oviparous, colubrid snake (Coluber constrictor L.) rises rapidly during the last half of incubation as the embryos increase in size. Although most of this calcium is drawn from stores in the yolk, hatchlings contain more calcium than was present in yolk of eggs at oviposition. Because shells from eggs incubated to hatching contain less calcium than do shells from freshly-laid eggs, the extra calcium appears to be drawn from the eggshell. Indeed, approximately 20% of the calcium required for development in this snake is obtained from the eggshell, with the remainder coming from the yolk. Thus, embryos of oviparous snakes, like embryonic chelonians, crocodilians and birds, withdraw calcium from their eggshells and do not rely exclusively on calcium supplied in their yolk for support of growth and development.

Animals↗
PubMed2003

[Snake bite epidemiology in the last 100 years in Brazil: a review].

We review 30 studies on snake bites in Brazil, published from 1901 to 2000, and conclude that epidemiological analyses conducted in the last 100 years are based on the same variables already identified by Vital Brazil in his pioneering report, i.e., characteristics of the individuals prone to snake bites, the bites themselves, and treatment. The original epidemiological profile was also maintained over the years and indicates that such accidents are more frequent among male farm workers in the 15-49-year age bracket, affecting mainly the lower limbs, and caused by snakes from genus Bothrops.

Adolescent↗
PubMed2000

Cryptosporidium serpentis oocysts and microsporidian spores in feces of captive snakes.

Fecal smears of 90 snakes, 29 lizards, and 8 turtles and tortoises were tested for Cryptosporidium spp. oocysts and microsporidian spores. Microsporidian spores measured mean = 3.7 microm in length and mean = 2.3 microm in width and were present in feces of 19 snakes and 1 lizard (16%); 13 of these snakes also shed Cryptosporidium serpentis oocysts. The oocysts were numerous in all positive samples, whereas microsporidian spores were always sparse, irrespective if whether fecal samples contained the oocysts. Retrospective examination of reptile clinical records revealed that all animals shedding microsporidian spores died naturally due to diseases, pathologic conditions, and clinical problems or were killed due to severe cryptosporidiosis. The present study indicates that microsporidian infections in reptiles have the features of an opportunistic infection.

Animals↗
PubMed1975

Metabolic effects of testosterone in the chequered water-snake, Natrix piscator.

In the water-snake, Natrix piscator, the following are depressed by orchidectomy and restored to normal by testosterone treatment: glucose, free and esterified fatty acids and triglycerides in plasma, hepatic triglycerides, and total esterified fatty acids. The increase in hepatic free fatty acids and muscle glycogen was also reduced to the level found in intact snakes. Moreover, although castration had no effect, testosterone caused a significant increase in liver weight and plasma protein, and a significant decrease in free plasma cholesterol. Except for an increase in triglyceride content by high doses of the hormone, neither castration nor the administration of 5 mg testosterone had any significant effect on the free fatty acid and triglyceride content of the adipose tissue of the snakes.

Adipose Tissue↗
PubMed1980

Sex of model and sex of subject in reduction of snake avoidance.

The effects of sex of experimenter on approach to a snake were assessed in both modeling and non-modeling conditions. Subjects were selected on the basis of a pretest in which they indicated that they would never pick up a harmless snake depicted on one of eight color slides of animals. 72 subjects (36 males and 36 females) served in one of 8 groups (4 groups of males and 4 groups of females). Each group of 9 subjects served in one of the following conditions: (a) a non-modeling condition with the same sex experimenter, (b) a non-modeling condition with an opposite sex experimenter, (c) a modeling condition with the same sex experimenter, and (d) a modeling condition with an opposite sex experimenter. All experimenters were selected to be attractive. Analysis of variance for scores on a 19-step sequence of approach yielded a significant interaction of sex of experimenter by sex of subject (F = 4.18, df = 1/64, p less than .05). All other comparisons were non-significant. Results indicate that an attractive experimenter of the opposite sex increases approaching a snake particularly by male subjects.

Animals↗