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PubMed2002

Using snakes to detect the intimal and adventitial layers of the common carotid artery wall in sonographic images.

This study presents an innovative automatic system for detecting the intima-media complex of the far wall of the common carotid artery by applying the snake techniques. Cohen's snake was modified and some criteria were added for our applications. In addition, the oscillating problem of using snakes was solved by properly choosing the time step from analysis of the frequency response of the filters. A time-diminishing gravity window, external forces, and a cost function assist the snake in selecting the optimal shape of intimal and adventitia layers. We compared the proposed snake and ziplock snake with respect to the manual extraction contour. The results show that the system can automatically detect the intimal and adventitial layers without any manual correction.

Algorithms↗
PubMed1998

Bothrops jararaca snakes produce several bothrojaracin isoforms following an individual pattern.

More than one isoform of bothrojaracin (BJC), a potent and specific thrombin inhibitor isolated from Bothrops jararaca venom, has been found in individual venoms collected from adult snakes. Variations in snake venom composition have previously been associated with factors such as age, sex, geographic origin, season of the year and diet. In order to obtain further information concerning individual patterns of expression of BJC isoforms, we have analyzed five individual Bothrops jararaca snake venoms collected at the same time from adult female snakes from the same geographic region. As expected, crude venoms showed a similar migration pattern on SDS-PAGE. BJC was purified using a procedure which includes an affinity chromatography step (PPACK-thrombin Sepharose). A slight variation in the amount of BJC obtained from individual venom samples was noticed. Inhibition of thrombin-induced platelet aggregation as well as migration pattern on SDS-PAGE (under reducing and non-reducing conditions) and isoelectric focusing varied considerably among BJC samples from the five snakes. The amino-terminal sequences (residues 1-34) of individual BJC samples were compared with the sequence deduced from isolated cDNAs encoding alpha and beta chains of BJC. A high degree of homology was detected, although some residues differed from one sample to other. Altogether, data confirmed the heterogeneity found for BJC purified from individual snakes. Thus, the results indicate that: (1) individual specimens of Bothrops jararaca have different patterns of BJC isoform expression; and (2) it seems that genetic factors, at least in part, determine the variability found in BJC production.

Amino Acid Sequence↗
PubMed2005

Identification of potent odorants in different cultivars of snake fruit [Salacca zalacca (Gaert.) Voss] using gas chromatography-olfactometry.

Three cultivars of snake fruits, Pondoh Hitam, Pondoh Super, and Gading, were freshly extracted using liquid-liquid extraction. The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using the nasal impact frequency (NIF) method. A total of 24 odor-active compounds were associated with the aroma of snake fruit. Methyl 3-methylpentanoate was regarded as the character impact odorant of typical snake fruit aroma. 2-Methylbutanoic acid, 3-methylpentanoic acid, and an unknown odorant with very high intensity were found to be responsible for the snake fruit's sweaty odor. Other odorants including methyl 3-methyl-2-butenoate (overripe fruity, ethereal), methyl 3-methyl-2-pentenoate (ethereal, strong green, woody), and 2,5-dimethyl-4-hydroxy-3[2]-furanone (caramel, sweet, cotton candy-like) contribute to the overall aroma of snake fruit. Methyl dihydrojasmonate and isoeugenol, which also have odor impact, were identified for the first time as snake fruit volatiles. The main differences between the aroma of Pondoh and Gading cultivars could be attributed to the olfactory attributes (metallic, chemical, rubbery, strong green, and woody), which were perceived by most of the panelists in the Pondoh samples but were not detected in the Gading samples. This work is a prerequisite for effective selection of salak genotypes with optimal aroma profiles for high consumer acceptance.

Arecaceae↗
PubMed2006

Immobility and supination in garter snakes (Thamnophis elegans) following handling by human predators.

A common response of animals to physical restraint is tonic immobility. The authors observed the behavior of garter snakes, Thamnophis elegans, in the field to determine the frequency of immobility as a response to handling. Most snakes fled after release, but the remainder remained immobile, sometimes on their backs (supination), for up to 10 min. Immobility was seen most often in pregnant snakes, which also were more likely than other snakes not to have moved before capture. Failure to move, either before or after capture, might be a consequence of the limited locomotory ability of gravid snakes. However, the lack of observations of interactions between snakes and their natural predators impedes researchers' understanding of the antipredator value, if any, of tonic immobility.

Animals↗
PubMedDate not supplied

Insights into population ecology and sexual selection in snakes through the application of DNA-based genetic markers.

Hypervariable genetic markers have revolutionized studies of kinship, behavioral ecology, and population biology in vertebrate groups such as birds, but their use in snakes remains limited. To illustrate the value of such markers in snakes, we review studies that have used microsatellite DNA loci to analyze local population differentiation and parentage in snakes. Four ecologically distinct species of snakes all show evidence for differentiation at small spatial scales (2-15 km), but with substantial differences among species. This result highlights how genetic analysis can reveal hidden aspects of the natural history of difficult-to-observe taxa, and it raises important questions about the ecological factors that may contribute to restricted gene flow. A 3-year study of genetic parentage in marked populations of the northern water snake showed that (1) participation in mating aggregations was a poor predictor of genetic-based measures of reproductive success; (2) multiple paternity was high, yet there was no detectable fitness advantage to multiple mating by females; and (3) the opportunity for selection was far higher in males than in females due to a larger variance in male reproductive success, and yet this resulted in no detectable selection on morphological variation in males. Thus genetic markers have provided accurate measures of individual reproductive success in this species, an important step toward resolving the adaptive significance of key features including multiple paternity and reversed sexual size dimorphism. Overall these studies illustrate how genetic analyses of snakes provide previously unobtainable information of long-standing interest to behavioral ecologists.

Animals↗
PubMed2000

Isolation and characterization of pepsinogen from Trimeresurus flavoviridis (Habu snake).

Pepsinogen was isolated from the gastric mucosa of Trimeresurus flavoviridis (Habu snake) by DEAE-cellulose and DEAE-Sepharose ion-exchange chromatographies, and Sephacryl S-200 gel-chromatography. The yield calculated from the crude extract was 29% with 6.2-fold purification. The purified pepsinogen gave a single band on both native- and SDS-PAGE. As no other active enzyme was detected on the chromatographies, it was concluded that the Habu snake has one major pepsinogen. The molecular mass of the pepsinogen was estimated to be 38 kDa by SDS-PAGE. The sequence of the N-terminal 26 amino acid residues was determined and compared with those of other pepsinogens. The N-terminal structure of Habu snake pepsinogen was more homologous with those of mammalian pepsinogens C than those of mammalian pepsinogens A. The pepsinogen was rapidly converted to pepsin by way of an intermediate form induced by acidification. The optimum pH of Habu snake pepsin for bovine hemoglobin was 1.5-2.0, and it retained full activity at pH 6.2 and 30 degrees C on incubation for 30 min. The optimum temperature for the snake pepsin was 50 degrees C and it was stable at 40 degrees C on incubation for 10 min. The proteolytic activity of the pepsin toward bovine hemoglobin was about two times higher than that of porcine pepsin A, however, the activity toward oxidized bovine insulin B-chain was lower than that of porcine pepsin A, and it did not hydrolyze oligopeptides. The specificity for oxidized bovine insulin B-chain of the pepsin was different from that of porcine pepsin A. Habu snake pepsin was inhibited by pepstatin A but not by serine, cysteine, or metallo protease inhibitors.

Amino Acid Sequence↗
PubMed1995

Snake-like chromatin in conjunctival cells of normal elderly persons and of patients with primary Sjögren's syndrome and other connective tissue diseases.

The aim of this study was to investigate the prevalence of snake-like chromatin in the nuclei of conjunctival cells of normal elderly persons, and to compare with findings in patients with connective tissue diseases other than primary Sjögren's syndrome and in age-matched patients with primary Sjögren's syndrome. Thirty-nine per cent of the eyes of normal controls contained snake-like chromatin. Snake-like chromatin has almost never been found in young normals, and the results of this study therefore raise the question of whether age may be a contributing factor. Snake-like chromatin was as frequent in patients with other connective tissue diseases as in patients with primary Sjögren's syndrome, and no correlation to the presence of keratoconjunctivitis sicca was found in this group. The presence of snake-like chromatin was significantly correlated to increased cell size (N/C ratio) and low goblet cell density. A marked correlation between snake-like chromatin and low values of break-up time was found in normals, whereas no correlation was found to the other standard tests for dry eye.

Adult↗
PubMed2006

Effect of lipids from Erabu sea snake, Laticauda semifasciata, on plasma glucose, insulin, and adipocytokine concentrations of normal and streptozotocin-diabetic mice.

AIMS: To clarify the influence of Erabu sea snake lipid on levels of plasma insulin and adipocyte-derived hormones. METHODS: Normal male mice (6 months) and streptozotocin-diabetic mice (a single administration, 150 mg/kg i.p.) were fed diets containing 10% fat as either lard or a mixture of 5% lard and 5% sea snake lipid for 4 months. RESULTS: The normal mice on the sea snake lipid diet had a significantly lower plasma glucose concentration (198 +/- 16 mg/dl; 148 +/- 11 mg/dl) than those mice on the lard diet. Although plasma insulin concentrations were not influenced by the dietary fat type, leptin (10 +/- 1 ng/ml; 16 +/- 2 ng/ml) and adiponectin (18 +/- 1 mug/ml; 21 +/- 1 mug/ml) concentrations were significantly higher in the sea snake lipid group than in the lard group. However, these effects of a sea snake lipid intake were not evident in the streptozotocin-diabetic mice. CONCLUSION: The results suggest that the decrease in plasma glucose following the intake of sea snake lipids could be related to a corresponding increase in leptin and adiponectin level.

Adiponectin↗
PubMed1996

Efficacy and potency of antivenoms in neutralizing the procoagulant effects of Australian snake venoms in dog and human plasma.

The efficacy and potency of Commonwealth Serum Laboratories (CSL) snake antivenoms in neutralizing the procoagulant action of Australian snake venoms was studied in vitro. The procoagulant action of venoms from Tiger, Brown and Taipan Snakes were measured in pooled canine or pooled human plasma. Mixtures of the venoms and their appropriate antivenoms, ranging from 0.1 to 15 times the recommended neutralizing dose of antivenom were then added to pooled canine or pooled human plasma and the efficacy and potency of the antivenoms in preventing the procoagulant action was measured. Neutralization was achieved by the addition of the appropriate antivenom in concentrations of 0.5 (Taipan), 10 (Tiger), 10 (Gwardar), 15 (Dugite) and an estimated 20 (Common Brown) times the dose expected. Similar results were obtained in canine and human plasma. The potency of Tiger and especially Brown Snake antivenom is substantially lower (10-20 times) than that predicted by CSL. These findings support an increase in the dose of antivenom to be used for the treatment of Tiger and especially Brown Snake envenomation complicated by coagulopathy. The in vitro canine model may be suitable for studying the procoagulant effects of Australian snake venoms.

Animals↗
PubMed1995

Spatial regulation of Drosophila snake protease activity in the generation of dorsal-ventral polarity.

Positional information along the dorsal-ventral axis of the Drosophila embryo is acquired through a signal transduction pathway which employs a extracellular protease cascade. The sequential activation of serine protease zymogens results in the ventrally localized production of a ligand in the perivitelline space of the embryo. Snake is one of several serine proteases which function in generating the ventralizing signal. Here, we investigate the biochemical properties of Snake in vivo and in vitro using recombinant forms of the protease. Wild-type Snake zymogen completely rescues embryos from snake null females when microinjected into the perivitelline space. Biochemical evidence for a covalently associated two-chain form of the activated protease is presented. The contribution of the activation peptide region to zymogen activation was addressed using site-directed mutagenesis. The phenotypic rescue properties of an autoactivated form of Snake reveal that the covalently associated proenzyme polypeptide chain suppresses a dominant effect associated with the activated catalytic chain alone. Recombinant active catalytic chain was produced and found to be short lived as a recombinant protein. These results suggest a model in which the proenzyme polypeptide both stabilizes and targets the Snake catalytic chain to a ventrally localized activation complex within the perivitelline space.

Animals↗
PubMed2001

Partial characterization of retroviruses from boid snakes with inclusion body disease.

OBJECTIVE: To characterize retroviruses isolated from boid snakes with inclusion body disease (IBD). ANIMALS: 2 boa constrictors with IBD and 1 boa exposed to an affected snake. PROCEDURE: Snakes were euthanatized, and tissue specimens and blood samples were submitted for virus isolation. Tissue specimens were cultured with or without commercially available viper heart cells and examined by use of transmission electron microscopy (TEM) for evidence of viral replication. Reverse transcriptase activ ty was determined in sucrose gradient-purified virus. Western blotting was performed, using polyclonal antibodies against 1 of the isolated viruses. Specificity of the rabbit anti-virus antibody was evaluated, using an immunogold-labeling TEM technique. RESULTS: 3 viruses (RV-1, RV-2, and RV-3) were isolated. The isolates were morphologically comparable to members of the Retroviridae family. Reverse transcriptase activity was high in sucrose gradient fractions that were rich in virus. Polyclonal antibody against RV-1 reacted with proteins of similar relative mobility in RV-1 and RV-2. By use of immunogold labeling, this antibody also recognized virions of both RV-1 and RV-2. CONCLUSIONS AND CLINICAL RELEVANCE: A retrovirus was isolated from boid snakes with IBD or exposed to IBD. Western blot analysis of viral proteins indicated that viruses isolated from the different snakes were similar. Whether this virus represents the causative agent of IBD is yet to be determined. The isolation of retroviruses from boid snakes with IBD is an important step n the process of identifying the causative agent of this disease.

Animals↗
PubMed1994

Medical studies of poisonous land and sea snakes.

The comparative toxicity and pathophysiology of thirteen (13) of poisonous snakes indigenous to the area in and around Saudi Arabia were determined. Four snakes from the Viperidae family, six from the Elapidae family, and three representative sea snakes from the family Hydrophiodae were included. Anesthetized adult Beagle dogs and anesthetized monkeys were used in the study. Vital physiologic functions were recorded continuously as were changes in the blood coagulation system and any tissue damage produced by the venom at the site of envenomation. Venom was administered intravenously or by an actual bite. Venom from the snakes of the family Viperidae produced death in an average of 3 hours. The average lethal dose was 1.13 mg/kg. Depression of 1st and 2nd stage clotting factors and a decrease in fibrinogen levels and in platelet counts were observed with these venoms. Findings suggestive of intravascular coagulation also were observed with moderate hemolysis of the formed elements. Some local hemorrhage was seen at the site of envenomation. Venom from the Elapidae family of snakes produced death at an average of 1.7 hours. The average lethal dose was 0.70 mg/kg. Death appeared to be primarily due to respiratory paralysis after blockade at the neuromuscular junction. Only moderate hemolysis was seen with these venoms. No intravascular coagulation or tissue damage was seen. The venom of the family Hydrophiodae consistently produced death in less than 30 minutes at an average dose of 0.06 mg/kg. Tissue damage was not observed, and changes were not observed in the hematologic parameters monitored.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

The mass of venom injected by two elapidae: the taipan (Oxyuranus scutellatus) and the Australian tiger snake (Notechis scutatus).

Using an enzyme immunoassay technique, a new method for measuring, in vivo, the mass of venom injected during snake bite, is presented. The venom injected into mice (as prey) and the venom left on the skin surface during bites by the two Australian Elapidae, the Taipan (Oxyuranus scutellatus) and the Tiger Snake (Notechus scutatus) has been measured. Venom delivery patterns vary significantly between these two species. In the case of the Tiger Snake (a total of 45 bites studied) the mean mass of venom injected in a first bite was 12.7 mg (S.E. 3.4 mg, median 8.1 mg); an average mass of 0.8 mg (S.E. 0.4 mg, median 0.17 mg) was left on the skin surface. A second bite delivered by the same snake yielded a mean venom mass only 27% of the first. In the case of the Taipan (a total of 24 bites) the mean venom mass injected in the first bite was 20.8 mg (S.E. 6.4 mg); with an average of 0.9 mg (S.E. 0.5 mg) left on the skin surface. In contrast to the situation observed with Tiger Snakes, second and third bites delivered in a rapid sequence yielded increasing masses of venom. The mean delivered in the third of a sequence of three bites was 48.8 mg (S.E. 23.8 mg). The ranges of venom mass, by species and by the sequence number of the bite, are also presented. In 66 of the 69 experimental bites studied in this report, venom could be easily detected, the species identified, and the absolute mass of venom measured.

Animals↗
PubMed1991

A comparative study of the biological properties of some sea snake venoms.

1. The protease, phosphodiesterase, alkaline phosphomonoesterase, L-amino acid oxidase, acetylcholinesterase, phospholipase A, 5'-nucleotidase, hyaluronidase, arginine ester hydrolase, procoagulant, anticoagulant and hemorrhagic activities of ten samples of venoms from seven taxa of sea snakes were examined. 2. The results show that venoms of sea snakes of both subfamilies of Hydrophiinae and Laticaudinae are characterized by a very low level of enzymatic activities, except phospholipase A activity and, for some species, hyaluronidase activity. 3. Because of the low levels of enzymatic activities and the total lack of procoagulant and hemorrhagic activities, venom biological properties are not useful for the differentiation of species of sea snakes. Nevertheless, the unusually low levels of enzymatic activities of sea snake venoms may be used to distinguish sea snake venoms from other elapid or viperid venoms.

5'-Nucleotidase↗
PubMed2005

Snake venom probes of platelet adhesion receptors and their ligands.

Snake venom proteins that modulate platelet adhesive interactions are chiefly from either of two main structural families: the C-type lectin-like family, or the metalloproteinase-disintegrins. Snake venom probes from both families selectively target platelet adhesion receptors, including glycoprotein (GP) Ib-IX-V, GP VI, alpha2beta1 and alphaIIbbeta3 (GP IIb-IIIa). These receptors act together to mediate platelet adhesion, activation and aggregation (thrombus formation) under hydrodynamic shear stress in flowing blood. The receptors are members of the leucine-rich repeat family (GP Ib-IX-V), the immunoglobulin superfamily (GP VI), or integrins (alpha2beta1, alphaIIbbeta3). In addition, adhesive glycoproteins in matrix and/or plasma such as von Willebrand factor (that binds GP Ibalpha and alphaIIbbeta3), collagen (that binds GP V, GP VI and alpha2beta1), or fibrinogen (that binds alphaIIbbeta3), are also targeted by C-type lectin family or metalloproteinase-disintegrin snake venom proteins. Emerging structural and functional evidence is beginning to explain how interactions between the conserved structural module-domains that make up these mammalian and snake proteins are regulated. Whether homologous adhesion/counter-receptors on platelets and other vascular cells are also potential snake venom targets is as yet largely unexplored.

Animals↗
PubMed2005

Snake venom fibrin(ogen)olytic enzymes.

Snake venoms contain a number of serine and metalloproteinases and included among these are the fibrin(ogen)olytic proteinases. Some years ago it was postulated that the fibrin(ogen)olytic enzymes may be clinically useful. Over the past 150 years a substantial body of literature has been generated on the identification and characterization of fibrin(ogen)olytic enzymes from a broad spectrum of snake species. In this review we describe the two different classes of fibrin(ogen)olytic enzymes isolated from snake venom and we summarize a number of studies aimed at characterizing the purified enzymes and/or their derivatives. Two distinct classes of venom fibrin(ogen)olytic enzymes have been previously identified, the metalloproteinases and serine proteinases. These two classes of proteinases differ in their mechanism of action and they target different amino acid sequences in fibrin(ogen), but each perform the same role in nature. When a snake envenomates its prey it needs a mechanism to facilitate the spread of the toxic components throughout the circulation. Fibrin(ogen)olytic enzymes break down fibrin rich clots and help to prevent further clot formation by their action on fibrinogen. This characteristic feature has led to development of fibrin(ogen)olytic snake venom enzymes as potential clinical agents to treat occlusive thrombi. Fibrolase, a fibrinolytic metalloproteinase isolated from Agkistrodon contortrix contortrix venom and the serine beta-fibrinogenolytic proteinase from Vipera lebetina have been chosen as representative enzymes from the two classes, and their biochemical and physiochemical properties will be described in detail. Finally, the characterization and development of alfimeprase, a recombinant fibrinolytic enzyme derived from fibrolase, as a clinical agent is described citing the progression from the laboratory bench to its current status as having successfully completed Phase II clinical trials.

Amino Acid Sequence↗
PubMed2005

From genome to "venome": molecular origin and evolution of the snake venom proteome inferred from phylogenetic analysis of toxin sequences and related body proteins.

This study analyzed the origin and evolution of snake venom proteome by means of phylogenetic analysis of the amino acid sequences of the toxins and related nonvenom proteins. The snake toxins were shown to have arisen from recruitment events of genes from within the following protein families: acetylcholinesterase, ADAM (disintegrin/metalloproteinase), AVIT, complement C3, crotasin/beta defensin, cystatin, endothelin, factor V, factor X, kallikrein, kunitz-type proteinase inhibitor, LYNX/SLUR, L-amino oxidase, lectin, natriuretic peptide, betanerve growth factor, phospholipase A(2), SPla/Ryanodine, vascular endothelial growth factor, and whey acidic protein/secretory leukoproteinase inhibitor. Toxin recruitment events were found to have occurred at least 24 times in the evolution of snake venom. Two of these toxin derivations (CRISP and kallikrein toxins) appear to have been actually the result of modifications of existing salivary proteins rather than gene recruitment events. One snake toxin type, the waglerin peptides from Tropidolaemus wagleri (Wagler's Viper), did not have a match with known proteins and may be derived from a uniquely reptilian peptide. All of the snake toxin types still possess the bioactivity of the ancestral proteins in at least some of the toxin isoforms. However, this study revealed that the toxin types, where the ancestral protein was extensively cysteine cross-linked, were the ones that flourished into functionally diverse, novel toxin multigene families.

Animals↗
PubMed1992

Diagnosis and treatment of confirmed and suspected snake bite. Implications from an analysis of 46 paediatric cases.

OBJECTIVE: To identify reliable predictors of envenomation in suspected snake bite and to examine the current standard of treatment in envenomed patients. DESIGN: Retrospective cohort analysis of children presenting with suspected or confirmed snake bite in southern mainland Australia. Detection of snake venom in urine or blood was taken as proof of envenomation. SETTING: Intensive Care Unit, Royal Children's Hospital, Melbourne. PATIENTS: Forty-six children presenting between 1979 and 1990. MAIN OUTCOME MEASURES: Positive and negative clinical evidence, venom tests, and coagulation tests. RESULTS: Twenty-seven children (59%) had suspected bites; 10 (22%) were bitten but not envenomed; 9 (19%) were envenomed. Two died of coagulopathy. Headache, abdominal pain or vomiting were moderately predictive of envenomation (positive predictive values of 63%, 57% and 64% respectively). Coagulopathy was a highly sensitive, specific and reliably predictive (100%) indicator of envenomation. The pressure-immobilisation bandage was used in 28% of cases at the scene of the bite and in 41% on contact with medical or paramedical services. Twelve patients received antivenom; of these, six received adrenaline as premedication. CONCLUSION: Headache, abdominal pain, nausea or vomiting, or abnormal coagulation tests accurately predict envenomation by snakes in southern mainland Australia. More or better education on first aid and clinical management of snake bite is needed.

Adolescent↗