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PubMed1978

Effect of feeding on plasma uric acid levels in snakes.

The effect of feeding on plasma-uric acid concentrations of the snake was studied. The values were monitored in 2 gopher snakes and 2 black rat snakes which were fed mice. Plasma uric acid values in snakes increased after eating and gradually returned to base line with the digestion of the mice. Uric acid concentrations were greater in snakes eating 2 mice than in those eating only 1 mouse. The base-line plasma uric acid concentration in snakes was approximately 2 to 5 mg/dl. Plasma uric acid concentrations may be useful in making a diagnosis of gout. Presence of gout is usually indicated by increased uric acid concentrations; however, interpretation of these concentrations should be based on information about the feeding schedule.

Animals↗
PubMed1980

Surface markers of lymphocytes in the snake, Spalerosophis diadema. I. Investigation of lymphocyte surface markers.

A specific antiserum was raised in rabbits against thymocytes from snakes, Spalerosophis diadema, and was absorbed repeatedly with snake erythrocytes and kidney cells. In complement-dependent cytotoxicity assays, the absorbed anti-thymocyte serum (ATS) was, at any given dilution, cytotoxic to Sp. diadema thymocytes > peripheral blood lymphocytes (PBL) > spleen cells and could be titrated to a plateau defining a population of about 98% of thymocytes, 80% of PBL and 72% of spleen cells. Antiserum directed against snake immunoglobulins was obtained by injecting rabbits with gamma-globulins separated from snake serum by DEAE-cellulose filtration. the anti-gamma globulin serum was absorbed with snake erythrocytes, and in indirect membrane immunofluorescence stained no thymocytes while reacted with about 15% of PBL and 29% of spleen lymphocytes up to a 1:8 dilution. Fluorescence of positive cells was distributed in spots, patches or caps; cap formation could be inhibited by maintaining the immunofluorescence test at +4 degrees. In each of six separate experiments performed during spring, the percentage of lymphocytes which reacted with anti-snake gamma-globulin serum complemented the percentage of cells recognized by ATS. It was shown, furthermore, that about 3%, 8% and 21% of lymphocytes from thymus, peripheral blood and spleen, respectively, possess a receptor for 2-mercaptoethanol-insensitive antibody-sheep erythrocyte complexes. The results indicate that lymphocyte structural heterogeneity exists in reptiles.

Animals↗
PubMed1981

Patterns of oral bacterial infection in captive snakes.

The bacterial isolates from culture specimens of snakes with infectious stomatitis were compared with those from culture specimens of the oral cavity of healthy captive snakes. Cloacal swab specimens were also taken from healthy snakes to compare their intestinal and oral bacterial populations. The healthy snakes had a predominantly gram-positive oral flora, with Corynebacterium spp and coagulase-negative Staphylococcus spp being the organisms isolated most frequently. The specimens from snakes with infectious stomatitis yielded predominantly gram-negative bacteria. The organisms most frequently isolated from these specimens were Pseudomonas aeruginosa, Providencia rettgeri, and P maltophilia. The cloacal swabbing of healthy snakes also resulted in the isolation of predominantly gram-negative organisms, suggesting that these bacteria are not exogenous pathogens but opportunistic invaders.

Animals↗
PubMed1994

Surface area to volume relationships of snakes support the use of allometric scaling for calculating dosages of pharmaceuticals.

Metabolic scaling is used to estimate pharmaceutical dosages for snakes because few pharmacokinetic studies have determined optimum dosages. The question arose as to the validity of the assumption of metabolic scale among snakes because they have such a cylindrical shape. The surface area to volume relationships of a group of animals is a major portion of the metabolic scaling exponent of 0.75. An assumption inherent in scaling pharmaceutical dosages for snakes is that there is not a shape change with a size change, or that scaling of the surface area to volume has an exponent of 0.66. One hundred forty snakes, 106 Colubridae and 34 Boiidae, were weighted, their volume was determined by water displacement, and the snakes were measured. Geometric formulas were used to calculate surface area and volume of each snake. Surface area to volume relationship was nearly isometric, with a scaling exponent of 0.64, supporting the use of metabolic scaling for estimating pharmaceutical doses.

Animals↗
PubMed1996

Assessment of the conventional detection of fecal Cryptosporidium serpentis oocysts in subclinically infected captive snakes.

Fecal specimens of seven captive snakes naturally subclinically infected with Cryptosporidium serpentis were monitored for 131 days for the presence and concentration of oocysts. Thirty-three of 81 (41%) of the monoclonal antibody positive stools were read as negative (sensitivity 59%) by the acid-fast-stained (AFS) fecal smears. Oocyst concentrations in the false-negative stools ranged between 6.0 x 10(3)/g to 2.5 x 10(4)/g. The experimentally determined concentration-threshold of oocyst detection by AFS fecal smear was 3.0 x 10(4)/g. The stool weights did not conform to a normal distribution; the oocyst concentration was significantly correlated with the stool weight (P < 0.01). Due to this correlation, stools which constituted less than 0.41% of the snake weight were classified as negative by the AFS fecal smears. The AFS fecal smear technique should be used exclusively for the determination of Cryptosporidium-positive snakes, but not for diagnosis of snake negativity for Cryptosporidium; it should be applied only for larger fecal specimens, such as those which constitute more than 0.41% of snake weight. At least five to seven stool samples should be examined by fecal smear in order to determine snake positivity for Cryptosporidium in subclinical infection.

Animals↗
PubMedDate not supplied

Practical applications of snake venom toxins in haemostasis.

Snake venom toxins have an established role in the coagulation laboratory for the assay of haemostatic parameters and a potential role for therapeutic treatment of thrombotic disorders. In the laboratory, snake venom thrombin-like enzymes (SVTLEs) are used for the assay of fibrinogen and detection of fibrinogen breakdown products and dysfibrinogenaemias. Importantly, because SVTLEs are not inhibited by heparin, they can be used for assaying antithrombin III and other parameters in samples which contain heparin. Prothrombin activators occur in many snake venoms and these have become established in the assay of prothrombin, in the study of dysprothrombinaemias and in the preparation of meizothrombin and non enzymic forms of prothrombin. Russell's viper (Daboia russelli) venom contains a number of useful compounds including toxins which can be used to assay blood clotting factors V, VII, X, platelet factor 3 and lupus anticoagulants (LA). More recently, activators from the taipan, Australian brown snake and saw-scaled viper have been used to assay LA. Proteins C and S can be measured by means of protac, a fast acting inhibitor from Southern copperhead snake venom and von Willebrand factor can be studied with botrocetin from Bothrops jararaca venom. The disintegrins, a large family of Arg-Gly-Asp (RGD)-containing proteins found in snake venoms, show great potential for the study of platelet glycoprotein receptors, notably, GPIIb/IIIa and Ib, and in the treatment of arterial thrombotic disease. Established SVTLEs used in clinical practice include ancrod and defibrase although success with these agents has been limited. A further group of enzymes under consideration as thrombolytic agents are the fibrinogenases.

Animals↗
PubMed2001

[In relation to Cleopatra and snake bites].

Cleopatra VII, one of the last Egyptian sovereigns of the ptolomeic dynasty, is envisioned as a mythic figure, surrounded by intrigues and mystery. her mysterious death was caused, according to history, by a snake bite. This article shows some instances of great Cleopatra's life and the state of the art on snake venoms. Even at the present time, snake bites are a public health problem in Asia, Africa, Central and South America, causing more than 25,000 deaths every year. Most snake venoms have a protein structure and cause neurotoxic and hemolytic effects, altering coagulation and fibrinolysis. The mortality due to snake bites fluctuates between 1 and 22%. Specific treatment includes the use of specific antiserums with highly purified components.

Animals↗
PubMed2002

Cross neutralization of dangerous snake venoms from Africa and the Middle East using the VACSERA polyvalent antivenom. Egyptian Organization for Biological Products & Vaccines.

This study was performed to assess the ability of polyvalent snake venom anti-serum, produced by the Egyptian Organization for Biological Products & Vaccines (VACSERA), to neutralize several toxic activities of snake venoms, not only of those included in the antivenom mixture, but also some additional venoms of snakes from Egyptian, African, and Middle Eastern habitats. In general, the results revealed that polyvalent snake venom anti-serum from VACSERA is highly effective in neutralizing Egyptian snake venoms, especially Naja haje, Naja nigricolles, Naja pallida, Cerastes cerastes, Cerastes cerastes cerastes, Cerastes vipera, Pseudocerastes persicus fieldi, and Walterinnisia egyptia. The antivenom was also effective against Naja haje, Walterinnisia egyptia, and Bites aritans from Saudi Arabia. High activity was obtained against venoms from Naja haje, Naja nigricolles, and Naja pallida of Sudan, as well as the African Naja melanoleuca, Naja mossambica, Naja naja oxiana, Bites gabonica, and Vipera lebetina. Only moderate effectiveness was obtained with Echis coloratus and Echis carinatus, and the polyvalent antiserum was ineffective against the venom of Naja nivea.

Africa↗
PubMed2000

Juvenile western toads, Bufo boreas, avoid chemical cues of snakes fed juvenile, but not larval, conspecifics.

Previous investigations have demonstrated the importance of predator diet in chemically mediated antipredator behaviour. However, there are few data on responses to life-stage-specific predator diets, which could be important for animals like amphibians that undergo metamorphosis and must respond to different suites of predators at different life-history stages. In laboratory choice tests, we investigated the chemically mediated avoidance response of juvenile western toads, Bufo boreas, to four different chemical stimuli: (1) live conspecific juveniles; (2) live earthworms; (3) snakes fed juvenile conspecifics; and (4) snakes fed larval conspecifics (tadpoles). Juvenile toads avoided chemical cues from snakes that had eaten juvenile conspecifics, but did not respond to the other three stimuli, including chemical cues from snakes fed larval conspecifics. In addition, the response to cues from snakes fed juveniles differed significantly from that of snakes fed larvae. To our knowledge, this is the first study to demonstrate the importance of diet in predator avoidance of juvenile anurans and the ability of juvenile toads to distinguish between chemical cues from predators that have consumed larval versus juvenile conspecifics. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Isolation and characterization of a novel proteinase inhibitor from the snake serum of Taiwan habu (Trimeresurus mucrosquamatus).

A proteinase inhibitor (designated as TMI) was isolated and purified from the snake serum of Taiwan habu (Trimeresurus mucrosquamatus) by using successive chromatographies which included Sephadex G-100, DEAE-Sephacel chromatographies, and C(4) reverse-phase HPLC. The purified inhibitor was shown to be a homogeneous protein with a molecular mass of about 47 or 36 kDa in the presence or absence of a reducing agent, beta-mercaptoethanol. The inhibitor decreases in molecular mass by about 23% with N-linked neuraminidase treatment, suggesting that it is a glycoprotein. Further enzymatic analyses indicated that this inhibitor possesses strong inhibitory activities toward three zinc-dependent metalloproteinases and not fibrinogenolytic serine proteases previously isolated from the venom of the same snake species with an IC(50) of about 0.2-1.1 microM. Its IC(50) value was approximately three orders of magnitude more effective than those of the tripeptide inhibitors we previously purified from the crude venom of the same snake (Biochem. Biophys. Res. Commun. 248, 562-568 (1998)). The purified inhibitor showed stronger inhibitory action against caseinolytic activities of crude venoms from closely related species of Taiwan habu than those from unrelated species. N-terminal sequence analysis showed that its sequence is distinctly different from sequences of those serum inhibitors reported for other snake species in the literature. Based on inhibition susceptibility and primary structures of various snake protease inhibitors, it is suggested that this novel inhibitor isolated from the serum of Taiwan habu may be a unique self-defense protein factor mainly for protection against envenomation from snakes of the same genus.

Amino Acid Sequence↗
PubMed2006

Polychlorinated biphenyls and organochlorine pesticides in plasma and the embryonic development in Lake Erie water snakes (Nerodia sipedon insularum) from Pelee Island, Ontario, Canada (1999).

From three locations along a 34-km shoreline of Pelee Island, Ontario, 30 gravid female Lake Erie water snakes (Nerodia sipedon insularum) were sampled to determine the organochlorine (OC) contaminant levels in plasma and the number of live and dead embryos present in the body cavity. Plasma was analyzed for 59 polychlorinated biphenyl (PCB) congeners and 14 organochlorine pesticides. Concentrations of pesticides were low (< or =0.1 ng/g wet wt) in all snakes, but there was significant variation in mean PCB concentrations in plasma from among the sampling locations on Pelee Island. Snakes (n = 5) from the West shore and dock area of the island had significantly higher PCB concentrations (90.4 +/- 15.0 ng/g wet wt) in plasma than those from Lighthouse Point (n = 5; 34.4 +/- 13 ng/g wet wt) and the south shore of the island (n = 5; 29.4 +/- 16.3 ng/g wet wt). Body mass of the female snakes ranged from 252 to 880 g, and mean masses were not significantly different among sample sites. The number of live embryos found ranged from 13 to 46 female snakes and no dead embryos were detected. There were significant positive correlations among body mass, snout-vent length, and number of young per female. There were no significant correlations among body mass, snout-vent length, number of young per female, or per-gram body mass of female snakes and contaminant concentrations in plasma. It was concluded that an interim estimate of a no-effect level on embryonic survival in N. sipedon insularum may be a maximum average concentration of 90.4 ng/g wet wt PCBs and a maximum average concentration of 3.6 ng/g wet wt p,p'-dichloro-diphenyl-dichloroethylene in plasma.

Animals↗
PubMed1996

Therapeutic efficacy of halofuginone and spiramycin treatment against Cryptosporidium serpentis (Apicomplexa: Cryptosporidiidae) infections in captive snakes.

The therapeutic effect of halofuginone hydrobromide (Steronol) and spiramycin solubilized (Spirasol) applied to clinical Cryptosporidium serpentis infections in captive snakes was investigated. Pathological changes induced by C. serpentis were typical for snake cryptosporidiosis. Spiramycin induced no significant change in the pattern of shedding of fecal Cryptosporidium oocysts; biopsies and necropsies revealed cryptosporidiosis in gastric mucosa of all spiramycin-treated animals. In all, 8 of 21 (38%) halofuginone-treated snakes stopped shedding C. serpentis oocysts; examination of gastric tissue of 6 of these 8 animals revealed cryptosporidiosis in 2 snakes. Hepatotoxic and nephrotoxic pathological changes induced by halofuginone included focal or multifocal, severe, acute liver necrosis; severe liver hemosiderosis; and bilateral, severe, acute diffuse cortical and tubular necrosis and iron deposition. Postprandial regurgitation associated with midbody swelling, observed in 4 halofuginone-treated and 2 spiramycin-treated snakes at 15 and 21 weeks after drug withdrawal, did not coincide with oocyst-positive feces. Neither halofuginone nor spiramycin treatment produced a satisfactory therapeutic outcome when applied against clinical C. serpentis infections in snakes.

Animals↗
PubMed2007

Snakes based segmentation of the common carotid artery intima media.

Ultrasound measurements of the human carotid artery walls are conventionally obtained by manually tracing interfaces between tissue layers. In this study we present a snakes segmentation technique for detecting the intima-media layer of the far wall of the common carotid artery (CCA) in longitudinal ultrasound images, by applying snakes, after normalization, speckle reduction, and normalization and speckle reduction. The proposed technique utilizes an improved snake initialization method, and an improved validation of the segmentation method. We have tested and clinically validated the segmentation technique on 100 longitudinal ultrasound images of the carotid artery based on manual measurements by two vascular experts, and a set of different evaluation criteria based on statistical measures and univariate statistical analysis. The results showed that there was no significant difference between all the snakes segmentation measurements and the manual measurements. For the normalized despeckled images, better snakes segmentation results with an intra-observer error of 0.08, a coefficient of variation of 12.5%, best Bland-Altman plot with smaller differences between experts (0.01, 0.09 for Expert1 and Expert 2, respectively), and a Hausdorff distance of 5.2, were obtained. Therefore, the pre-processing of ultrasound images of the carotid artery with normalization and speckle reduction, followed by the snakes segmentation algorithm can be used successfully in the measurement of IMT complementing the manual measurements. The present results are an expansion of data published earlier as an extended abstract in IFMBE Proceedings (Loizou et al. IEEE Int X Mediterr Conf Medicon Med Biol Eng POS-03 499:1-4, 2004).

Animals↗
PubMed1987

Development of specific IgE antibodies after repeated exposure to snake venom.

A patient who had been working with snakes for many years developed urticarial lesions on contact with the venom of the poisonous rinkals (Haemachates haemachatus). More recently, the patient complained of generalized allergic reactions occurring within minutes of exposure to the venom. The patient's serum, but not control sera, contained IgE antibodies that reacted with the specific snake venom in an ELISA and was demonstrated to associate with a 66 kd component of the venom with Western blotting. With an ELISA, the patient's serum was also demonstrated to contain IgG antibodies to the specific snake venom and to venom from three other snakes with which the patient had previously been in contact. The possibility of an acute allergic reaction should be considered in individuals continuously working with snakes or in individuals who have previously been bitten by snakes.

Adult↗
PubMed2004

The efficacy of two antivenoms against the in vitro myotoxic effects of black snake (Pseudechis) venoms in the chick biventer cervicis nerve-muscle preparation.

Neurotoxicity is rarely seen following human systemic envenoming by Australasian black snakes (genus Pseudechis) with myotoxicity being the most prominent feature following bites by some species. This study investigated the in vitro myotoxicity of venoms from seven species of Australasian Pseudechis and determined the efficacy of CSL black and tiger snake antivenoms. All Pseudechis venoms (10 microg/ml) significantly inhibited direct twitches of the chick biventer cervicis nerve-muscle preparation (p<0.05, one-way ANOVA). Prior addition of black snake antivenom (5 U/ml) prevented the inhibitory effects of all Pseudechis venoms (p<0.05, one-way ANOVA), except Pseudechis butleri. Prior addition of tiger snake antivenom (5 U/ml) prevented the venom-induced reduction in direct twitches to Notechis scutatus venom and all Pseudechis venoms (p<0.05, one-way ANOVA), with the exception of Pseudechis australis and Pseudechis colletti venoms. Black or tiger snake antivenom (5 U/ml) added 1 h after the addition of venom inhibited further reduction of direct twitches by N. scutatus and most Pseudechis venoms, but did not significantly restore twitch height. PLA2 activity was found in all venoms with the following rank order: Pseudechis porphyriacus>P. australis>Pseudechis papuanus>P. butleri>Pseudechis guttatus> or =Pseudechis pailsii>P. colletti>N. scutatus. The results of the present study suggest that Australasian Pseudechis venoms possess variable myotoxic activity. The ability of black or tiger snake antivenom to prevent or inhibit further venom-induced effects varied across the genus.

Animals↗
PubMed2006

Corticosterone and the transition from courtship behavior to dispersal in male red-sided garter snakes (Thamnophis sirtalis parietalis).

Seasonal modulation of baseline glucocorticoid concentrations as well as the sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis plays an important role in supporting critical life-history events such as seasonal reproduction and migration. Despite numerous studies on adrenocortical modulation, little is known about the exact timing of this seasonal modulation with respect to critical life-history stages. We tested the hypothesis that seasonal modulation of the HPA axis during the spring mating season in male red-sided garter snakes (Thamnophis sirtalis parietalis) is temporally linked to the mechanisms regulating dispersal. We compared hormonal responses to capture stress in courting male red-sided garter snakes collected from the den site and den perimeter to those of dispersing snakes collected 0.6 km from the den. We also investigated possible changes in steroid hormones during the spring mating season. These studies support previous findings that plasma androgen and corticosterone concentrations significantly decline over the mating season. Our results demonstrate that males 0.6 km into a 15-20 km route to the feeding grounds have lower baseline corticosterone concentrations than male snakes actively courting at the den. Dispersing males also exhibit a typical stress response marked by a significant increase in corticosterone while actively courting males do not. Capture stress did not significantly influence androgen concentrations of either courting or dispersing male red-sided garter snakes. There were no significant differences in body composition indices among male snakes collected from the den, den perimeter, or 0.6 km away from the den. However, we did observe a significant negative correlation between baseline corticosterone levels and body composition indices. These data suggest that breeding is a distinct stage accompanied by specific physiological parameters that differ from those during dispersal to the feeding grounds. Our results indicate that declining baseline corticosterone concentrations may play a role in the behavioral switch between actively courting and dispersing (i.e., feeding) in the late spring.

Analysis of Variance↗
PubMed2004

Trophic and maternal transfer of selenium in brown house snakes (Lamprophis fuliginosus).

Excessive concentrations of dietary Se are toxic to oviparous vertebrates (i.e., fish and birds) but little is known about its accumulation and effects in reptiles. We exposed female brown house snakes, Lamprophis fuliginosus, to 10 and 20 microg/g Se by injecting seleno-D,L-methionine into their prey items and compared the snakes to individuals receiving background levels of approximately 1 microg/g dietary Se. Snakes were fed meals equaling 25% of their body mass 2-3 times a month for 10 months. Snakes exposed to excessive Se accumulated significant concentrations of Se in kidney, liver, and ovarian tissue, but accumulation had no effect on female survival, food consumption, growth, or body condition. Fewer females exposed to excessive Se reproduced than females exposed to 1 microg/g Se (67% vs. 91%, respectively), but the reduction in reproductive activity was not statistically significant. Total reproductive output of females did not differ among the three dietary treatments. However, snakes exposed to 10 and 20 microg/g Se transferred significant concentrations of Se to their eggs. In the 20 microg/g treatment, maternal transfer resulted in Se concentrations in eggs that surpassed all suggested reproductive toxicity thresholds for birds and fish. Further studies are needed to more rigorously determine whether maternal transfer of Se in this snake species affects the viability of developing embryos or the health of offspring.

Animals↗
PubMed2001

Prey targeting by the infrared-imaging snake Python molurus: effects of experimental and congenital visual deprivation.

Boid and crotaline snakes possess two distinct types of organ evolved to image radiant electromagnetic energy: the lateral eye, which responds to visible light, and the pit organ, which responds to infrared radiation. While infrared imaging may allow accurate predatory targeting in complete absence of visual information, both infrared and visual information are probably normally involved in prey targeting. We examined the roles of vision and infrared imaging in Python molurus predatory performance under conditions of (1) high visual contrast; (2) very low visual contrast; (3) complete blinding; (4) experimental monocular occlusion; and (5) congenital monocularity. Normally sighted pythons were equally successful at targeting white (BALB/c) and black (C57BL6/J) mice (Mus domesticus) against a black background. Binocularly occluded snakes exhibited strike angles and distances similar to non-occluded snakes, but exhibited lower strike success, suggesting that high visible contrast is not required for accurate targeting, but that precise targeting depends to some degree upon visual information. Strike angles, distances and latencies were indistinguishable between snakes subjected to experimental monocular occlusion and normally sighted snakes. However, snakes congenitally lacking one eye preferentially targeted on the sighted side. Thus, accurate targeting of highly mobile homeothermic prey by Python can be accomplished with little or no visual information, but performance can be affected by complete visual deprivation or by alteration of visual input during development. The developmental effects of early visual deprivation in this system provide a novel opportunity to investigate the neural integration of two electromagnetic radiation-imaging systems in a single animal.

Animals↗