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PubMed2006

Influence of body size on swimming performance of four species of neonatal natricine snakes acutely exposed to a cholinesterase-inhibiting pesticide.

Locomotor performance is an important fitness-related trait in reptiles because of its potential influence on prey capture and predator avoidance. Because cholinesterase-inhibiting pesticides disrupt neuromuscular signaling, reduction in performance seems to be a logical translation of this biochemical disruption to the organism level. In the present study, we compared the swimming performance of four species of natricine snakes acutely exposed to a formulation of carbaryl to determine whether neonatal body size or skin permeability influences responsiveness. Exposure to high concentrations of carbaryl (2.5-5.0 mg/L) resulted in reduced swimming performance in all four species of snakes, and species responded similarly to the pesticide once body size was accounted for allometrically. Using traditional methods in physiological ecology to estimate skin permeability (a parameter that influences the dose of contaminant absorbed), we found that water flux across the integument also scaled allometrically with body surface area and, therefore, was similar among species after controlling for this relationship. We suggest that future studies examining the effects of repeated low-dose exposure to cholinesterase inhibitors on performance parameters will be useful in assessing the ecological significance of our findings.

Animals↗
PubMed2006

Induction of cytochrome P4501A in African brown house snake (Lamprophis fuliginosus) primary hepatocytes.

Although there have been numerous studies involving fish, birds, and mammals, little is known about the response of the cytochrome P4501A system of snakes to halogenated aromatic hydrocarbons (HAHs). The present study describes the induction of ethoxyresorufin-O-deethylase (EROD) in primary hepatocytes of the African brown house snake (Lamprophis fuliginosus). Hepatocytes were exposed in multiwell plates to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and four different non-ortho-substituted coplanar polychlorinated biphenyls (PCBs 77, 81, 126, and 169). Exposure to TCDD and PCB 126 resulted in a dose-dependent increase in EROD activity, with maximum inducible EROD activities of 177 +/- 56 (mean +/- SEM) and 101.1 +/- 55 pmol/min/mg protein for TCDD and PCB 126, respectively. None of the other PCBs caused a measurable induction of EROD, which suggests reduced inducibility of snake hepatocytes compared to some vertebrate taxa. Median effective concentrations (EC50s) were 0.16 +/- 0.03 nM for TCDD and 8.25 +/- 4.14 nM for PCB 126. The relative potency (REP20-80) range for PCB 126 was 0.044 to 0.046. Compared to results from in vitro systems using other vertebrate species, both the maximum inducibility and the REPs estimated for L. fuliginosus were within the same range as those reported for mammals and the more sensitive bird species but were greater than the values reported for most fish species. In conclusion, induction of EROD activity in primary hepatocytes appears to be a useful approach for evaluating the dioxin-like potencies of aryl hydrocarbon-receptor agonists in snakes. The test system offers a method for rapid screening of reptilian responsiveness to these compounds using smaller numbers of organisms than with in vivo studies, an important consideration for many declining reptile species.

Animals↗
PubMed1995

A Golgi study on the nucleus sphericus of the striated snake, Elaphe quadrivirgata.

The intrinsic organization of the nucleus sphericus (NS) was studied in the striated snake using the rapid Golgi method. The NS is a large aggregation of cells located in the posterior portion of the telencephalon and is, as a whole, cup-shaped with its hilus oriented in the rostral direction. From the periphery inward, the following three concentric layers were discernible: a marginal layer, mural layer and hilar layer. The marginal layer consists of scattered cells extending dendrites internally toward the hilar layer and externally into the anterior commissure (AC). The mural layer contains densely packed polygonal neurons with dendrites extending internally into the hilar layer and externally toward the marginal layer. The hilar layer consists of scattered cells whose dendrites extend in a transverse direction, distributing mainly in the hilar layer. The axons of the neurons in the marginal and mural layers travel rostromedially, and some axons can be traced into the AC, while those of the neurons in the hilar layer run rostrally, and some are lost among fibers of the accessory olfactory tract (AOT). The afferents to the NS are derived mainly from the AOT and AC. The AOT fibers travel caudally in a thick bundle through the hilus and are distributed totally within the hilar layer, forming a dense fiber plexus. The AC fibers enter the nucleus from the rostromedial aspect and run in an arched course, emitting numerous fine short collaterals.

Afferent Pathways↗
PubMed2003

Vine snake (Thelotornis capensis) bite in a dog.

A vine snake bite in a dog is reported. There was continued minor bleeding from the assumed nose bite site for 4 days. Currently manufactured snakebite antivenom is not effective against vine snake bites and treatment is supportive.

Animals↗
PubMed1995

Electroencephalographic abnormalities in patients with snake bites.

Electroencephalograms (EEGs) were obtained for 26 patients with snake bite to observe the cerebral impact of snake venom. All snakes were identified; 19 (73%) were Russell's vipers, one (4%) was a common cobra, five (19%) were hump-nosed vipers, and one (4%) was a dog-faced fresh water snake. The EEG was abnormal in 25 patients (96%) and these results included all the snake species identified. The EEG abnormalities observed were reduced alpha activity, increased theta/beta activity or sharp waves (grade 1), sharp waves or spikes and slow waves (grade 2), or diffuse delta activity (grade 3). Grade 1 changes occurred in 16 patients (62%), grade 11 in eight patients (31%), and grade 111 in one patient (4%). Thus, grade 2 and 3 changes, which were moderately severe to severe abnormalities, occurred in nine patients (35%). One patient had acute renal failure and two others had mild jaundice and hyponatremia. These three patients had EEG abnormalities that were similar to those observed in the remaining 22 patients. The altered EEG, suggestive of an encephalopathy, appeared within hours of the bite and persisted for several days without clinical neurologic effects. The changes were seen mainly in the temporal lobe. Similar changes occurred in both patients with and without antivenom therapy. It appeared that the EEG abnormalities are a consequence of the effects of venom from the bites of a variety of snakes.

Adolescent↗
PubMed1995

Snake bites in adults from the Asir region of southern Saudi Arabia.

One hundred thirty-two cases of snake bites in adults from the Asir region of southern Saudi Arabia occurring the period 1989-1992 were studied. Of 15 snakes killed, 10 were identified as Echis coloratus and five as were Coluber rhodorachis. The clinical presentation of those bitten by the 10 identified E. coloratus were not very different from cases in which the snake was not identified, favoring the conclusion that the commonest snakes inflicting bites in this region are the saw-scaled or carpet vipers of the genus Echis. The response of adults to bites in this region is generally benign. Patients present mainly with local swelling, pain, redness, and coagulopathy. Minor bleeding was seen in 18.2% of the patients, primarily at the bite site. No serious complications or fatal bleeding occurred. Bites are more common in males during the summer season and mainly in the low land (Tihama). Recommendations regarding management of snake bites of adults from the Asir region are outlined.

Adolescent↗
PubMed2003

Degenerative encephalopathy in a coastal mountain kingsnake (Lampropeltis zonata multifasciata) due to adenoviral-like infection.

In March 2000, an approximately 30-yr-old, male coastal mountain kingsnake (Lampropeltis zonata multifasciata) presented with disequilibrium and unresponsiveness to stimuli that ultimately lead to euthanasia. Histologically, there were foci of gliosis primarily within the caudal cerebrum, brainstem, and cervical spinal cord. Several glial cells and endothelial cells contained magenta, intranuclear inclusion bodies. Electron microscopy of the inclusions revealed paracrystalline arrays of 79-82 nm, viral-like particles. DNA in situ hybridization of sections of formalin-fixed brain using a mixture of two digoxigenin-end-labeled, adenovirus specific, oligonucleotide probes at low and high stringency was positive for adenovirus.

Adenoviridae↗
PubMed1998

[Acute management of patients bitten by poisonous snakes].

The management of poisonous snake bites includes first aid and clinical medical treatment. First aid consists of reassurement of the patient, immobilisation of the bitten limb and rapid transport to the nearest hospital to monitor the vital functions. In no case suction, incision or tight bandages should be applied. The degree of envenomation can be classified in three categories depending on the spread of the symptoms: no symptoms, only local non-progressive symptoms, and systemic or local rapidly progressive symptoms (severe envenomation). Antivenin therapy is indicated in severe envenomation. Because of the risk of anaphylactic reactions or serum sickness, antivenin should be given with great caution. Antibiotic therapy and tetanus prophylaxis are advised in all cases. Immediate consultation with the National Intoxication Centre of the Rijksinstitut voor Volksgezondheid en Milieu (RIVM) is always warranted; telephone: 030-2748888. In a national protocol, which is available at the RIVM, the Harbour Hospital Rotterdam, the Academic Medical Centre and Artis Zoo Amsterdam, the correct management of snake bites is described. An overview of all antivenins available in the Netherlands is also given in this protocol.

Anaphylaxis↗
PubMed1999

Endocytic active zones: hot spots for endocytosis in vertebrate neuromuscular terminals.

We have used a sensitive activity-dependent probe, sulforhodamine 101 (SR101), to view endocytic events within snake motor nerve terminals. After very brief neural stimulation at reduced temperature, SR101 is visualized exclusively at punctate sites located just inside the presynaptic membrane of each terminal bouton. The number of sites (approximately 26 sites/bouton) and their location (in register with postsynaptic folds) are similar to the number and location of active zones in snake motor terminals, suggesting a spatial association between exocytosis and endocytosis under these stimulus conditions. With more prolonged stimulation, larger SR101-containing structures appear at the bouton margins. Thus endocytosis occurs initially at distinct sites, which we call "endocytic active zones," whereas further stimulation recruits a second endocytic paradigm.

Animals↗
PubMed1999

Reference hematologic and plasma chemistry values of brown tree snakes (Boiga irregularis).

Reference hematologic and plasma chemistry values were determined from 103 blood samples collected from 53 clinically healthy brown tree snakes (Boiga irregularis). Female snakes had significantly higher mean plasma values for total solids, total protein, calcium (Ca), phosphorus (P), uric acid, and blood monocyte percentage than did males, whereas males had significantly higher mean plasma fibrinogen values. The variances for hematocrit, monocyte percentage, azurophil percentage, plasma total solids, plasma total protein, albumin, Ca, and P also differed significantly between sexes. The higher mean values and greater variances for plasma total protein, plasma total solids, Ca, and P in the female snakes were probably associated with yolk synthesis and accumulation.

Animals↗
PubMed1999

[Spread of hemoparasites in reptiles and amphibians in Italy].

Hemoparasites were harvested from 993 individuals belonging to 15 reptilian and 1 amphibian species, from various Italian localities. Hemogregarins were found in 10 reptilian species while a flagellate and microfilariae were found only in Tarentola mauritanica from Lampedusa. For each host species and place of origin the frequencies of hemogregarins are reported and discussed. Longitudinal studies with periodical thin smears were carried out on 5 Tarentola mauritanica, 4 Lacerta viridis, 26 Podarcis filfolensis, 10 Podarcis muralis, 38 Podarcis sicula, 8 Chalcides ocellatus. This material, whose study has not yet been completed, is made available by the author who strongly encourages further investigations on this subject.

Animals↗