Biochemical and biological analysis of Philodryas baroni (Baron’s Green Racer; Dipsadidae) venom

Philodryas baroni—an attractively colored snake—has become readily available through the exotic pet trade. Most people consider this species harmless; however, it has already caused human envenomation. As little is known about the venom from this South American opisthoglyphous “colubrid” snake, herein, we studied its protein composition by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), as well as its effects on the hemostatic system. Both reducing and nonreducing SDS-PAGE analysis demonstrated that the venom exhibits greatest complexity in the range of 50–80 kDa. The venom displayed proteolytic activity toward azocollagen, with a specific activity of 75.5 U mg−1, and rapidly hydrolyzed the Aα-chain of fibrinogen, exhibiting lower activity toward the Bβ- and γ-chains. The venom from P. baroni showed no platelet proaggregating activity per se, but it inhibited collagen- and thrombin-induced platelet aggregation. Prominent hemorrhage developed in mouse skin after intradermal injection of the crude venom, and its minimum hemorrhagic dose was 13.9 μg. When injected intramuscularly into the gastrocnemius of mice, the venom induced local effects such as hemorrhage, myonecrosis, edema, and leucocyte infiltration. Due to its venom toxicity shown herein, P. baroni should be considered dangerous to humans and any medically significant bite should be promptly reviewed by a qualified health professional.

Purification and characterization of patagonfibrase, a metalloproteinase showing α-fibrinogenolytic and hemorrhagic activities, from Philodryas patagoniensis snake venom

Venoms of Colubridae snakes are a rich source of novel compounds, which may have applications in medicine and biochemistry. In the present study, we describe the purification and characterization of a metalloproteinase (patagonfibrase), the first protein to be isolated from Philodryas patagoniensis (Colubridae) snake venom. Patagonfibrase is a single-chain protein, showing a molecular mass of 53,224 Da and an acidic isoelectric point (5.8). It hydrolyzed selectively the Aalpha-chain of fibrinogen and when incubated with fibrinogen or plasma, the thrombin clotting time was prolonged. Prominent hemorrhage developed in mouse skin after intradermal injection of patagonfibrase. When administered into mouse gastrocnemius muscle, it induced local hemorrhage and necrosis, and systemic bleeding in lungs. Patagonfibrase showed proteolytic activity toward azocasein, which was enhanced by Ca(2+) and inhibited by Zn(2+), cysteine, dithiothreitol and Na(2)EDTA. Patagonfibrase impaired platelet aggregation induced by collagen and ADP. Thus, patagonfibrase may play a key role in the pathogenesis of disturbances that occur in P. patagoniensis envenomation, and may be used as a biological tool to explore many facets of hemostasis.

Proteolytic, edematogenic and myotoxic activities of a hemorrhagic metalloproteinase isolated from Bothrops alternatus venom

A hemorrhagic metalloproteinase has been isolated from Bothrops alternatus venom from specimens that inhabit the north-east region of Argentina. The present study aimed at evaluating the proteolytic, hemorrhagic, edematogenic and myotoxic activities of the purified metalloproteinase, in order to consider its participation on the phatophysiology of the intoxication by Bothrops alternatus venom. The hemorrhagic metalloproteinase was isolated by a combination of DEAE-Cellulose chromatography and gel filtration on Sephadex G-75. The enzyme showed a molecular mass around 55k Da, it exhibited a hemorrhagic activity with a minimal hemorrhagic dose of 1.9 microg, almost two fold minor than the whole venom (3.6 microg). The enzyme showed a weak proteolytic activity on casein (18.72 U/mg enzyme), similar to the one exhibited by the whole venom (20 U/mg venom). Besides, the ability to degrade casein could be detected by SDS-PAGE; beta-casein was the fraction that showed the higher degradation, followed by alphas(1)-casein and kappa-casein degradation. The hemorrhagic metalloproteinase rapidly hydrolysed the A alpha-chain of fibrinogen, followed by B beta-chain degradation and leaving the gamma-chain unaffected. Proteolytic activities were inhibited by EDTA whereas they were not inhibited by benzamidine and PMSF. The metalloproteinase showed several polypeptides chains after autocatalytic processing, including a chain of 28k Da, it could be the processed disintegrin-like and cysteine-rich domains. The isolated enzyme exhibited myotoxic activity with high CK levels at 6h, due to local ischemia resulting of its hemorrhagic activity, and a significant edema-inducing effect (MED=1.3 microg), corroborated both results by the histological observations of samples of gastrocnemius muscle. These findings showed that this hemorrhagic metalloproteinase, possesses high edematogenic and myotoxic activities and, in despite of exhibiting a weak proteolytic activity, it is able to degrade fibrinogen. So, this enzyme would contribute markedly to the phatophysiology of the bothropic envenomation.

Muscle and skin necrotizing and edema-forming activities of Duvernoy's gland secretion of the xenodontine colubrid snake Philodryas patagoniensis from the north-east of Argentina

Philodryas patagoniensis is a colubrid snake spread by all South America, but very little is known about the composition and biological activities of its Duvernoy's gland secretion. In order to characterize it, we studied edematogenic, dermonecrotic and myonecrotic activities. For edematogenic activity, solutions containing different amounts of secretion were injected s.c. in the right foot pad of mice, both feet were subsequently cut off and weighed individually. For myonecrotic activity, mice were injected i.m. with solutions containing 40 microg of secretion, and at various time intervals mice were bled to determine serum creatine kinase activity and gastrocnemius muscles were removed for microscopic examination (Hematoxylin-Eosin stain). For dermonecrotic activity, solutions containing different amounts of secretion were injected into the shaved dorsal skin of mice; the necrotic lesion was measured on the inner surface of the skin and trimmed for microscopic examination (Hematoxylin-Eosin stain). Phospholipase A(2) activity was evaluated using a kinetic method. Results showed that P. patagoniensis Duvernoy's gland secretion exhibits a high edematogenic activity and moderate myonecrotic and dermonecrotic activities, while lacking phospholipase A(2) effect. Regarding edema, a 30% increase in the weight was produced by injecting 0.26 microg of Duvernoy's gland secretion. Microscopically, myonecrosis reached its highest intensity 12 h after injection, which was also demonstrated by serum creatine kinase levels. Dermonecrosis was proportional to the amount of secretion injected, with a minimum necrotizing dose of 15.7 microg. Myonecrotic, edematogenic and dermonecrotic activities were inhibited when the secretion was pre-incubated with 1 mM Na(2)EDTA. This suggests that the enzymes responsible for those activities are mostly metalloproeinases. All the studies carried out up to now demonstrate the potential toxicity of P. patagoniensis Duvernoy's gland secretion (which inhabits the north-east region of Argentina) and that the local lesions caused by this colubrid snake are very similar to those found in bothropic accidents. This latter suggests a more careful evaluation of the victims when considering the medical treatment to be adopted.

Hemorrhagic activity of the Duvernoy's gland secretion of the xenodontine colubrid Philodryas patagoniensis from the north-east region of Argentina

Colubrid snakes belonging to Philodryas genus, widespread all over South America, bring about lesions (swelling, ecchymosis, transient bleeding from the bite site punctures), that are similar to those produced by Bothrops species (yarará). In the present work we began the characterization of Philodryas patagoniensis venom. We examined if this venom produces hemorrhagic lesions as those observed in victims bitten by Philodryas olfersii. Hemorrhagic, proteolytic and fibrinogenolytic activities were evaluated, and histological observations in samples of gastrocnemius muscle were carried out. Inhibition studies were carried out in metal chelator (ethylenediaminetetraacetic acid) presence. Our results show a small Minimum Hemorrhagic Dose (MHD=0.035 microg) and a high proteolytic activity (143 U/mg), and prove the capacity of this venom to degrade fibrinogen in vitro rendering it unclottable by thrombin, supporting the presence of proteases, principally metalloproteases, in P. patagoniensis venom that are able to alterate the vascular wall and degrade fibrinogen, being both activities responsible of a high hemorrhagic activity.

Muscular regeneration after myonecrosis induced by Bothrops jararacussu snake venom from Argentina

Venom from Bothrops snake produces severe local symptoms on the envenomed victim, such as hemorrhage, edema and myonecrosis. The latter is perhaps the most important of all, since antivenom therapy is not effective for it, even when antivenom is injected only a few minutes after the accident. In this work, mice weighing 18-20 g (n = 5) were inoculated with 70 micrograms Bothrops jararacussu venom in 0.1 ml PBS in the gastrocnemius muscle. Mice were sacrificed using ether after 1, 12 hours, 3, 5, 7 days and 2, 3, 5, 6 weeks after the injection of the venom to obtain gastrocnemius muscles. They were fixed with Bouin's solution and stained using Hematoxylin--Eosin and Mason's trichromic stain was applied to visualize collagen fibers. Results showed that inflammatory reaction was evident after a few minutes of the venom injection, which was not evident after 6 weeks. Muscular fiber necrosis reached its highest level on the seventh day. Even thought regeneration of muscular fibers was important, they never reached the size of the control. We conclude that Bothrops jararacussu venom causes severe necrosis on muscle fibers with partial recovery, showing low hemorrhage and abundance of granulation tissue. This points that not all fibers were regenerated, which can be seen as a functional sequel for injured muscle.

American rattlesnake (Crotalus durissus terrificus) bite accidents in dogs in Argentina

The symptomatology and treatment of two dogs bitten by Crotalus durissus terrificus are described. Neurological signs were present few minutes after the accident with local anesthesia and ataxia of the affected limb and neurotoxic fascia. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine kinase (CK), lactate dehydrogenase (LDH) and calcium were evaluated in an attempt to investigate muscle damage. Renal failure was not observed but some alterations were detected in urine. Urine density was low and the urinary sediment contained granular clumps and small round cells. Muscle samples were obtained from both legs for histopathological study, showing edema and isolated necrotic fibers. Both dogs received treatment within four hours after the accident by intravenous route. The antivenom was administered diluted in 250ml of Ringer solution in a dose enough to inactivate more than 8mg of venom. Dexamethasone was applied previously to the antivenom. Clinical evolution was good and both patients were in good health condition on the second day after the accident.

[Hemorrhagic and edema-forming activity and histologic changes in the mouse footpad induced by venoms from Argentinian Bothrops and Crotalus genuses]

Hemorrhagic, oedema-forming activities and histopathological alterations in the mouse footpad induced by Bothrops and Crotalus snake venoms from Argentina. Hemorrhagic and oedema-forming activities of various Bothrops and Crotalus snake venoms from Argentina were studied, together with histological alterations in the mouse footpad. The highest oedema-forming activity was found in the venom of B. jararaca, followed by B. jararacussu, B. neuwiedii diporus, B. alternatus, and Crotalus durissus terrificus. Regarding hemorrhage, the highest activity was found in the venom of B. neuwiedii diporus, followed by B. jararacussu, B. alternatus, and B. jararaca. No hemorrhage was observed after injection of Crotalus durissus terrificus venom, in agreement with histological observations of injected footpads. Histological analysis revealed a conspicuous inflammatory reaction in the injected footpad, characterized by oedema and an inflammatory infiltrate rich in polymorphonuclear leucocytes. Necrotic blood vessels and dilated lymphatic vessels were observed after injection of B. jararaca and B. jararacussu venoms, and myonecrosis was evident in tissue of mice injected with B. alternatus and B. neuwiedii diporus.

[Hemorrhage induced by snake venoms in Argentina]

Mice of 18 and 20 g were injected intradermally with 0.1 ml of serial dilution of venom in saline solution 0.9 buffered pH 7.2. Groups of 4 animal were formed, they were sacrificed 2 hours after inoculation. Skin of every mouse was put out, and the haemorrhagic area was measured Bothrops alternatus, Bothrops jararaca, Bothrops jararacussu and bothrops neuwiedii venoms were used. Crotalus durissus terrificus did not show any haemorrhagic activity.

[Edema and myonecrosis induced by Bothrops jararaca venom of Argentina in mice]

Myonecrotic and oedema-inducing activities of Bothrops jararaca of Argentina were studied. For oedema-inducing activity 0.05 ml of different solutions of venom in 0.9% NaCl were injected in mice. The dose of 0.86 micrograms/20 g mouse induced an oedema of 30% respect the other member in one hour. The myonecrotic effects were studied injecting mice gastrocnemius muscle with 70 micrograms of venom in 0.1 ml of 0.9% NaCl, which were sacrificed in different time. The inoculation area was obtained for hystophatological process. Animal sacrificed 30 minutes after the inoculation showed oedema, hemorrhage and inflammatory infiltrate. Those sacrificed in one and three hours after the inoculation also had got necrosis.