(American lance-headed vipers) - Bothrops and related genera

The coagulant, defibrinating, fibrino lytic and fibrinogenolytic activities of venoms from ten species of Costa Rican crotaline snakes were studied, together with the neutralization of these effects by a polyvalent antivenom. The venoms of Bothrops asper, B. schlegelii, A. nummifer, B. godmani, Lachesis muta and Crotalus durissus induced a coagulant effect in vitro, and all of them, with the exception of B. nummifer, also induced defibrination in vivo. Like the other anti-coagulant venoms (B. lateralis, B. ophryomegas, B. nasuta and A. picadoi) induced a degradation of the alpha (A) chain of fibrinogen, thereby inhibiting coagulation. However, they did not induce defibrination upon i.v. injection. All of the venoms showed fibrinolytic activity in vitro.

Polyvalent antivenom is effective in the neutralization of coagulant, defibrinating, fibrinolytic and fibrinogenolytic activities of these venoms, with the exception of coagulant effect induced by C. durissus venom. Since only three venoms are used in the immunization of horses, these results demonstrate the high degree of immunological cross reactivity between components affecting coagulation in Costa Rican crotaline snake venoms.

An extremely high procoagulant activity of the venom of newborn Bothrops specimens has been demonstrated.

Atropoides nummifer (Jumping viper)

B. nummifer is significant not so much in its lethality, which is less than other members of the genus, but rather in its unusual and frightening ability to jump or lunging a distance equal to the length of its body toward the victim. Bites are lethal due to hemorrhagic, edema-forming, proteolytic, hemolytic, hyaluronidase and fibrinolytic activities of the venom(Rojas et al. 1987). The venom also contains small mytoxins, the toxic effects are mediated by the formation of nonspecific ionic pores in the sarcolemma and/or T-tubule muscle membrane. (Brus'es et al. 1993).

A myotoxin from the venom of the snake Bothrops nummifer has been purified to homogeneity. The toxin is a basic dimer with a subunit molecular weight of 16,000, lacks phospholipase A2 activity yet induces skeletal muscle damage. The myotoxin shows partial immunologic identity with a myotoxic phospholipase A2 isolated from Bothrops asper venom.

Atropoides picadoi

The edema-forming activity is among the highest activity being present in the venoms of Bothrops species and hemorrhaging is also severe. It is among the four non-coagulant venoms (B. lateralis, B. ophryomegas, B. nasuta and B. picadoi) that induce a degradation of the alpha (A) chain of fibrinogen, thereby inhibiting coagulation. However, they do not induce defibrination upon i.v. injection. All of the venoms show fibrinolytic activity in vitro. Polyvalent antivenom are effective in the neutralization of coagulant, defibrinating, fibrinolytic and fibrinogenolytic activities of these venoms. Since only three Bothrops venoms are used in the immunization of horses, these results demonstrate the high degree of immunological cross reactivity between components affecting coagulation in Costa Rican crotaline snake venoms.

Bothriechis schlegeli (Eyelash viper)

Although not considered capable of delivering a lethal bite, severe bites are possible due to the arboreal nature of this snake which results in many of the bites being in the head or neck region. In severe bites, systemic effects can include paralysis. This specie is more toxic towards man than members of bothrops. B. schlegelii venom contains both acidic and basic PLA2s.

Bothrops alternatus (Urutu)

While not as dangerous as B. atrox or lancelotus, B. alternatus (urutu) still causes extensive local tissue damage and is capable of death. In one study, ll patients had local pain and oedema; prolonged clothing time was present in 96.9% of the cases, haemorrhage in 40.6%, blisters in 21.9% and necrosis in 9.4%. A tourniquet was used by 43.8% of the patients. A median of 4 ampoules of antivenom were administered. There was no death in this series. There was no significant trend between increasing age and necrosis, nor between time interval between bite and antivenom administration and occurrence of blisters or necrosis. Presence of blister(s) was associated with necrosis (p = 0.007), but use of a tourniquet, altered clotting time or presence of haemorrhage were not. These findings, compared with those of case series of bites of other species of Bothrops, and contrary to the popular belief, indicate that B. alternatus bite is not always severe, and has even a lower rate of complications(Bauab et al. 1994)

The effects on lethal potency and enzymatic activity were determined following alkylation, with p-bromophenacyl bromide, of the acidic toxic phospholipase A2 from Bothrops alternatus. The modified B. alternatus enzyme, which lost its enzymatic activity, retained considerable toxicity. Histopathologic studies on mice have demonstrated features similar to those of the native enzyme. However, the distribution of the damage was different and the survival time was longer. It is concluded that the enzyme activity is not important for the lethal action of the enzyme although it influences the distribution of the damage and survival time.

Purified phospholipase A2 from Bothrops alternatus venom is one single protein species with a molecular weight of 15,000 and isoelectric point 5.08. When injected i.p. or i.v. at a dose of 0.7 microgram/g body weight it is lethal to mice, eliciting a typical syndrome of dyspnea, tachycardia, arrhythmia and irreversible shock. Post mortem and histopathologic studies have demonstrated that the lungs (massive pulmonary hemorrhage), heart (foci of myocardial and endocardial necrosis with interfibrillar hemorrhage), liver (congestion, hepatocytic microvacuolization with zones of massive necrosis) and kidneys (foci of tubular and glomerular necrosis) were severely injured. Except for the less extensive hemorrhages and the significantly longer survival time, the observed lesions are similar to those observed after the injection of lethal doses of whole venom. The lethal potency of the purified enzyme (LD50 i.p. 0.14 microgram/g body weight) is 46-fold greater than that of the whole venom (LD50 i.p. 6.4 micrograms/g body weight). The contribution of phospholipase A2 to the overall lethal effect of B. alternatus venom is suggested by the decreased lethal potency of a venom sample in which a significant amount of phospholipase A2 has been removed and the full restoration of the lethal potency upon supplementation of the depleted sample with purified enzyme. It is concluded that phospholipase A2 is a major component responsible for lethality of the whole B. alternatus venom, while the contribution of other venom components appears to be significant mainly in reducing the time of survival.

B. asper - (Terciopelo)

One analysis of the venoms from juvenile and adult Bothrops asper snakes revealed that the former has a strong prothrombin- converting activity, the latter contained mainly a thrombin- like, fibrinogen-converting enzyme [Kornal'ik, 1990 #825]. In addition, the venoms of ten newborn (less than 10 days of age) specimens completely lacked myotoxin bands, indicating an ontogenetic regulation in the expression of these toxins in B. asper. 5. One of the bands, corresponding to the lysine-49 phospholipase myotoxin II, was the only isoform present in all individuals studied, suggesting a possible selective pressure for the conservation of this type of protein in the venom of B. asper. (Lomonte and Carmona 1992) . Crude venom of this species affects muscle cells in two ways: by direct action of myotoxin (s) and by ischemia due to hemorrhage. (Guti'errez et al. 1984).

Another paper did a comparative study of venoms of newborn and adult specimens of Bothrops asper from two Costa Rican populations: San Carlos, in the Atlantic versant and Puriscal in the Pacific. Comparison was on a basis of determination of the following effects: hemorrhage, myonecrosis, edema, proteolysis, hemolysis, and lethality, as well as neutralization of the lethal effect by polyvalent antivenom. Biochemical and immunochemical comparisons were done by means of electrophoresis, immunoelectrophoresis, and immunodiffusion. There are marked differences between newborn and adult venoms from both regions in electrophoretic and immunoelectrophoretic patterns, although the immunodiffusion plates showed an almost identical pattern. Venoms from newborn specimens are more proteolytic, hemorrhagic, edema-forming and lethal, whereas those of adult specimens are more hemolytic and induce a stronger myonecrotic action, characterized by a myolitic type of necrosis. Antivenom neutralizes the lethality of all venoms with similar ED50. Venoms of adult specimens from both regions showed a slight variation in the immunoelectrophoretic pattern, but a complete identity in immunodiffusion plates. Adult venoms from San Carlos were more hemorrhagic, and myonecrotic, whereas those of Puriscal were more proteolytic, having similar lethality, edema-forming activity, and hemolytic effect. The same differences were observed when venoms from newborn specimens from both populations were compared.

Three hemorrhagic factors (BaH1, BH2 and BH3) were isolated from the venom of Bothrops asper. They contain 55% of the total hemorrhagic activity of the whole venom when they are mixed, but lose almost half of the activity if they are separated, indicating a synergism between the three. The main hemorrhagin is BaH1 (Bothrops asper hemorrhagin 1); the other two are weak hemorrhagins but contribute to the synergism. They are acidic proteins with a pI of 4.5, 5.2 and 5; their mol. wt is 64,000, 26,000 and 55,000 respectively. The hemorrhagic activity of all three factors was inhibited by EDTA and ortho-phenathroline, indicating that the hemorrhagic activity is metal dependent. Phosphoramidon, soybean trypsin inhibitor, PMSF, pepstatin and aprotinin did not affect the hemorrhagic activity of the isolated factors. (Borkow et al. 1993) No immunological cross-reactivity was observed between BaH1 and BaP1, two hemorrhagic metalloproteinases isolated from B. asper venom, by gel immunodiffusion, Western blotting and neutralization studies. Cross-reactivity was detected with antisera against these toxins in several crotaline and viperine snake venoms by ELISA, whereas no reactivity was observed with either antiserum against the venoms of Bothrops nummifer, Crotalus durissus terrificus, Vipera russelli and several elapid venoms. Antiserum against native BaH1 neutralized hemorrhagic activity of the venoms of B. asper, B. atrox, B. jararaca, Crotalus atrox, C. durissus durissus, Echis carinatus and Trimeresurus flavoviridis, being ineffective against the venoms of Agkistrodon bilineatus and Lachesis muta. (Rucavado et al. 1995).

BaP1 is another hemorrhagic metalloproteinase found in this venom but smaller than the others in having a mol. wt of 24,000. BaP1 induces edema and a mild myotoxic effect, lacking coagulant, defibrinating and lethal effects. (Guti'errez et al. 1995)

A basic, dimeric myotoxic protein, myotoxin II, purified from Bothrops asper venom has a similar molecular weight and is immunologically cross-reactive with antibodies raised to previously isolated B. asper phospholipases A2, except that it shows only 0.1% of the phospholipase activity. Its 121 amino acid sequence, determined by automated Edman degradation, clearly identifies it as a Lys-49 phospholipase A2. Myotoxin II shows greater sequence identity with other Lys-49 proteins from different snake venoms (Agkistrodon piscivorus piscivorus, Bothrops atrox, and Trimeresurus flavoviridis) than with another phospholipase A2 active Asp-49 molecule isolated from the same B. asper venom. This work demonstrates that phospholipase activity per se, is not required in phospholipase molecules for either myotoxicity or edema inducing activities. (Francis et al. 1991)

B. cotiara

B. cotiara, formerly found in the South of Brazil, is now threatened with extinction. Its venom contains a highly hemorrhagic fraction (Pessatti et al. 1995). In addition, the venom of newborn B. cotiara possesses the highest thrombin-like activity of any Bothrops species .

B. erythromelas

The activity of the factor II (FII) activator in the crude venom of this species is about 30 times greater than that in Oxyuranus scutellatus venom and the level of FX activator activity, which was CA2+ ion dependent, was similar to that in Daboia russelli venom. The venom also has two haemorrhagic factors (58 and 105 kDa) and two fibrinolytic enzymes (18 and 58 kDa). (Maruyama et al. 1992)

Bothrops godmani (Godmann's pit viper

Two basic myotoxic phospholipases A2 from the venom of Bothrops godmani from Costa Rica have molecular weights of 14,300 (myotoxin I) and 13,400 (myotoxin II) and isoelectric points of 8.2 (myotoxin I) and 8.9 (myotoxin II). Both toxins induce drastic myotoxic effects. In addition, myotoxin I has high phospholipase A2 activity and is potently anticoagulant, whereas myotoxin II has a very low phospholipase A2 activity and is only weakly anticoagulant. Immunochemical data indicate that both toxins are immunologically related to Bothrops asper myotoxins, although B. godmani myotoxin II gives a stronger cross- reactivity when tested with antisera raised against B. asper myotoxins I and II (D'Iaz et al. 1992).

B. jararaca (jararaca)

Botrocetin shares a significant degree of sequence homology with Alboaggregin-B from T. albolabris

Crude venom from Bothrops jararaca has procoagulant, platelet aggregating and phospholipase A2 (PLA2) activities. In bites by this species, localized tissue destruction is much more pronounced than that by the B. alternatus. This snake is of similar toxicity as B. atrox, however delivers considerably less venom per bite, averaging only 40-70 mg. This is, however, equal to a lethal dose so a bite from an adult jararaca must be considered life-threatening. Many deaths have resulted from bite of this specie due to the commonness and aggressiveness. As is widespread in Bothrops species, bites caused by young Bothrops jararaca are more likely to cause blood incoagulability in humans than bites caused by adult Bothrops jararaca. (Ribeiro and Jorge 1989).

Bothrojaracin is a thrombin inhibitor; devoid of phospholipase A2, amidolytic or fibrino (geno) lytic activity. This component forms a noncovalent complex with alpha-thrombin, without changing its catalytic activity on small peptide substrates and ehaves as a potent and specific antagonist of thrombin-induced platelet aggregation and secretion (Zingali et al. 1993).

Bothrombin is a fibrinogen clotting serine protease that alpha-thrombin, splits off fibrinopeptide A without releasing fibrinopeptide B (Nishida et al. 1994).

Bothropstoxin is myotoxin consisting of 121 amino acids.

Botrocetin induces von Willebrand factor (vWF)-dependent platelet agglutination and has been proposed as an alternative agent to ristocetin for evaluating vWF function. However, important differences between the vWF-platelet interactions induced by these two agents have suggested that different regions of vWF and the platelet may be involved in the interactions induced by the two agonists (Fujimura et al. 1987)

Jararafibrase I and II are low molecular weight fibrinolytic/hemorrhagic enzymes (Tanigawa et al. 1994).

Jararhagin is an inhibitor of integrin collagen receptor aII/bI. This 421 AA 55 kDa component modulates binding of vWF to the glycoprotein Ib-IX complex on platelets through a specific interaction with the vWF A1 domain. Also blocks aII/bI-dependent platelet adhesion to collagen. Comparison of jararhagin with disintegrin precursors highlights the modular arrangement of proprotein, metalloprotease, and disintegrin domains in the metalloprotease/disintegrin family and provides an insight into their biosynthesis and evolution (Paine et al. 1992)

Jararhagin-C is 28 kDa-protein with inhibitory activity on collagen- and ADP- induced platelet aggregation. Its complete amino acid sequence corresponded to the carboxyl-terminal region consisting of disintegrin-like and cysteine-rich domains of jararhagin, a high molecular weight hemorrhagic metalloprotease. Sequence homology of the protein to other disintegrins and disintegrin-like proteins from various snake venoms present (Usami et al. 1994).

Jararafibrases I and are fibrinolytic enzymes displaying haemorrhagic activity. To elucidate the mechanisms involved and the role of the enzymatic activity in haemorrhage (Maruyama et al. 1992)

PA-BJ is another serine protease affecting platelet aggregation activity (Serrano et al. 1995).

B. jararacussu (jararcussu)

Clinical effects are similar to that of the jararaca and the venom also contains bradykinin like peptides. Myonecrosis is one of the effects of Bothrops jararacussu venom, from which a myotoxin has been isolated showing structural homology to phospholipase A2 (PLA2), but without enzymatic activity. Such myotoxic activity is also present in the Crotalus durissus terrifucus venom, and is attributed to crotoxin and to PLA2 (crotoxin B), the basic component of the crotoxin complex. This venom shows three proteins with immunologic identity to PLA2 from crotoxin (dos et al. 1992).

Bothropstoxin I is one myotoxic phospholipase from the venom (Guti'errez et al. 1991). This 13,700 mol. wt myotoxic phospholipase homologue is devoid of PLA2, proteolytic or hemolytic activities, inhibits muscle twitch tension (Heluany et al. 1992).

Peptide P is bradykinin potentiating peptide that induces lowering of arterial pressure thorugh inhibition of angiotensin-converting enzyme (Ferreira et al. 1992). This component was made into the pharmaceutical drug captopril.

B. lanceolatus (fer-de-lance)

B. lanceolatus is a large, dangerous snake and, unlike other members of this genus, injects hemotoxins as well as neurotoxins. Bites are complicated by severe pulmonary embolism a few hours after envenomation. This thromboembolic complication develops despite heparin therapy and wisas followed by disseminated intravascular coagulation (DIC). Vascular thrombosis and pulmonary embolism are rare after Bothrops lanceolatus snake bite as patients are usually hypocoagulable due to DIC (Estrade et al. 1989).

B. moojeni (Caissaca)

Bothrops moojeni envenomations produce great increment in swelling, necrosis and infection, mild decrement in coagulation action and sometimes fatal extradural haematoma. (Kouyoumdjian and Polizelli 1989).

MPB - A basic metalloproteinase active on casein was isolated from Bothrops moojeni venom by chromatography on Sephadex G- 100, DEAE-Sephacel, SP-Sephadex C-50 and Sepharose 12. The enzyme, named MPB, is not hemorrhagic and presents only traces of blood-clotting activity. On polyacrylamide gel electrophoresis at pH 4.3, MPB presented a single and diffuse protein band. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme presented two protein bands corresponding to mol. wts of 65,000 and 55,000, which stained with Schiff's reagent. The proteolytic activity of MPB was inhibited by ethylenediaminetetracetate, 1,10-phenanthroline and dithiothreitol. The proteolytic activity of MPB and the serine proteinases MSP 1 and MSP 2 on natural substrates indicates differences in hydrolytic specificity among these enzymes. All fibrinogen chains were degraded by the three proteinases, but MPB is the most active. On fibrin, the proteinases hydrolyzed only the alpha-chain and alpha-polymer, leaving the beta-chain and gamma-dimer apparently untouched. The native type I collagen was partially hydrolyzed by the three enzymes but no digestion product was detected. On the contrary, calf and guinea-pig skin type I gelatins were readily digested by MSP 1 and MSP 2 producing different hydrolysis patterns. MPB was the least active proteinase on the gelatins. The digestion of fibronectin showed an inversion in the specificity of these proteinases. MPB was the most active on fibronectin, while MSP 1 and MSP 2 promoted a faint, partial hydrolysis on this protein. (Serrano et al. 1993)

The serine proteinases MSP1 and MSP2 cleave the insulin B-chain at identical positions and in the same order of bond cleavage. Cleavage occurs first at the Arg- Gly(22-23) position, followed by hydrolysis of the Lys-Ala(29- 30) peptide bond. The metalloproteinase MPB differs from the serine proteinases in cleaving the insulin B-chain very rapidly at four positions: Ser-His(9-10), Ala-Leu(14-15), Tyr-Leu(16- 17) and Phe-Phe(24-25). (Reichl et al. 1993)

Bothrops moojeni myotoxin II, which have extremely low phospholipase A2 activity. (D'Iaz et al. 1991)

The major proteolytic enzyme of this species ; Moojeni protease A, is a proteolytic enzyme that hydrolyzes type I collagen, gelatin, fibrinogen, fibrin and the B-chain of oxidized insulin. The proteinase cleaves the A alpha-chain faster than the B beta-chain of human fibrinogen and shows no effect on the gamma-chain (Reichl and Mandelbaum 1993).

B. neuwiedi (jararaca pintada)

A very common Argentinian snake, while not being particularly toxic is responsible for many bites and is a significant clinical factor. The main clinical signs are local edema followed by necrosis and sloughing of the skin. (Mendez and Riet 1995) Patient present hemorrhagic necrosis at the envenomization site and considerable bleeding from venous puncture sites. This is accompanied by severe defibrination syndrome, fibrinogen is not measurable by clotting time assays. Fibrin degradation products are greatly elevated. In vitro experiments revealed that B. neuwiedi venom directly activates Factors II and X, but does not activate Factor XIII. In vivo consumption of Factor XIII after B. neuwiedi envenomization is ascribed to the action of Factor IIa. At low venom concentrations clotting is initiated by activation of prothrombin by the venom either directly or via Factor X activation. Treatment with heparin might be beneficial in coagulopathy secondary to snake bite by reducing circulating active thrombin. The venom contains thrombin-like proteases which cause slow clotting of fibrinogen, and plasmin- like components causing further proteolysis of fibrinogen and fibrin. Antivenom has no effect on the proteolytic action of the snake venom. The in vivo effects of antivenom are presumably caused by acceleration of the elimination of venom components from the circulation. Intravenous administration of antivenom caused normalization of blood coagulation parameters within 48 h. (Dempfle et al. 1990)

NHF is the major hemorrhagic factor. The factors of Bothrops species seem to be structurally similar. The hemorrhagic proteins from the venoms of Lachesis, North American Crotalus, Asian Trimeresurus and Agkistrodon species show some resemblance to the Bothrops factors. The venom hemorrhagic principles from snakes of the Viperinae subfamily (Bitis and Vipera species) might have few epitopes similar to those of Bothrops species as the only relation shown is the partial neutralization by the immune sera. [Mandelbaum, #538]

Isozymes P-1 and P-2are PLA2s that induce edema (Daniele et al. 1995)

A prothrombin activator from the venom of Bothrops neuwiedi has also been purified. Results indicate that the venom activator belongs to the metalloproteinases. The structural and functional properties of the venom prothrombin activator from B. neuwiedi are similar to those reported for the venom activator from Echis carinatus. (Govers et al. 1987)

B. pirajai

Piratoxin-1 is a myotoxic protein of 121 AA that is highly homologous with bothropstoxin-I (Mancuso et al. 1995).

B. pradoi

As with most other Bothrops species, the venom is highly edema forming and mytoxic.

B. punctatus

The venom is extremely defibrinating leading to profoud coagulation problems.

Porthidium nasutum (Hognosed viper)

B. picadoi, like the other anti-coagulant venoms B. lateralis, B. ophryomegas, and B. nasuta,) induces a degradation of the alpha (A) chain of fibrinogen, thereby inhibiting coagulation. However, they did not induce defibrination upon i.v. injection. All of the venoms showed fibrinolytic activity in vitro

Lachesis muta (Bushmaster)

Initial symptoms are similar to those of bothropic envenomation: intense pain, nausea, vomiting, sweating, and excitability, but differing in the magnitude of a tremendous edema and in the absence of intensive bleeding and phlyctenae. There are also important alterations in arterial blood pressure and in the activity and concentration of coagulation factors (Bolanos et al. 1982)

The venom contains serine proteases similar to gyroxin and components isolated from Bothrops species. The enzyme cleaves only fibrinopeptide A from fibrinogen; it does not activate factor XIII and is devoid of kallikrein-like activity (Silveira et al. 1989).

Stenoxobin is an example of these clotting enzymes acting upon human fibrinogen by releasing consecutively fibrinopeptides A + B from the alpha and beta chains of fibrinogen; (Aragon and Gubensek 1993)

References

Aragon, O.-F. and F. Gubensek (1993). "A thrombin-like enzyme from bushmaster (Lachesis muta stenophyrs) venom." Toxicon 31(11): 1435-43.

Bauab, F. A., G. R. Junqueira, M. C. Corradini, P. V. Silveira and S. d.-A. Nishioka (1994). "Clinical and epidemiological aspects of the 'urutu' lance- headed viper (Bothrops alternatus) bite in a Brazilian hospital." Trop-Med-Parasitol 45(3): 243-5.

Bolanos, R., O. Rojas and F.-C. E. Ulloa (1982). "[Biomedical aspects of 4 cases of snake bites by Lachesis muta (Ophidia: Viperidae) in Costa Rica]." Rev-Biol-Trop 30(1): 53-8.

Borkow, G., J. M. Guti'errez and M. Ovadia (1993). "Isolation and characterization of synergistic hemorrhagins from the venom of the snake Bothrops asper." Toxicon 31(9): 1137-50.

Brus'es, J. L., J. Capaso, E. Katz and G. Pilar (1993). "Specific in vitro biological activity of snake venom myotoxins." J-Neurochem 60(3): 1030-42.

D'Iaz, C., J. M. Guti'errez and B. Lomonte (1992). "Isolation and characterization of basic myotoxic phospholipases A2 from Bothrops godmani (Godman's pit viper) snake venom." Arch-Biochem-Biophys 298(1): 135-42.

D'Iaz, C., J. M. Guti'errez, B. Lomonte and J. A. Gen'e (1991). "The effect of myotoxins isolated from Bothrops snake venoms on multilamellar liposomes: relationship to phospholipase A2, anticoagulant and myotoxic activities." Biochim-Biophys-Acta 1070(2): 455-60.

Daniele, J. J., I. D. Bianco and G. D. Fidelio (1995). "Kinetic and pharmacologic characterization of phospholipases A2 from Bothrops neuwiedii venom." Arch-Biochem-Biophys 318(1): 65-70.

Dempfle, C. E., R. Kohl, J. Harenberg, W. Kirschstein, D. Schlauch and D. L. Heene (1990). "Coagulopathy after snake bite by Bothrops neuwiedi: case report and results of in vitro experiments." Blut 61(6): 369-74.

dos, S.-M. C., L. R. Goncalves, D.-C. L. Fortes, Y. Cury, J. M. Guti'errez and M. d.-F. Furtado (1992). "[The efficacy of the bothropic-crotalic antivenom in the neutralization of the main Bothrops jararacussu venom effects]." Rev-Inst-Med-Trop-Sao-Paulo 34(2): 77-83.

Estrade, G., D. Garnier, F. Bernasconi and Y. Donatien (1989). "[Pulmonary embolism and disseminated intravascular coagulation after being bitten by a Bothrops lanceolatus snake. Apropos of a case]." Arch-Mal-Coeur-Vaiss 82(11): 1903-5.

Ferreira, L. A., O. B. Henriques, I. Lebrun, M. B. Batista, B. C. Prezoto, A. S. Andreoni, R. Zelnik and G. Habermehl (1992). "A new bradykinin-potentiating peptide (peptide P) isolated from the venom of Bothrops jararacussu (jararacucu tapete, urutu dourado)." Toxicon 30(1): 33-40.

Francis, B., J. M. Gutierrez, B. Lomonte and I. I. Kaiser (1991). "Myotoxin II from Bothrops asper (Terciopelo) venom is a lysine- 49 phospholipase A2." Arch-Biochem-Biophys 284(2): 352-9.

Fujimura, Y., L. Z. Holland, Z. M. Ruggeri and T. S. Zimmerman (1987). "The von willebrand factor domain-mediating botrocetin-induced binding to glycoprotein IB lies between Val449 and Lys728." Blood 70(4): 985-8.

Govers, R.-J. W., M. J. Knapen, G. Tans, R. F. Zwaal and J. Rosing (1987). "Structural and functional characterization of a prothrombin activator from the venom of Bothrops neuwiedi." Biochim-Biophys-Acta 916(3): 388-401.

Guti'errez, J. M., J. N'Unez, C. D'Iaz, A. C. Cintra, B.-M. I. Homsi and J. R. Giglio (1991). "Skeletal muscle degeneration and regeneration after injection of bothropstoxin-II, a phospholipase A2 isolated from the venom of the snake Bothrops jararacussu." Exp-Mol-Pathol 55(3): 217-29.

Guti'errez, J. M., C. L. Ownby and G. V. Odell (1984). "Pathogenesis of myonecrosis induced by crude venom and a myotoxin of Bothrops asper." Exp-Mol-Pathol 40(3): 367-79.

Guti'errez, J. M., M. Romero, C. D'Iaz, G. Borkow and M. Ovadia (1995). "Isolation and characterization of a metalloproteinase with weak hemorrhagic activity from the venom of the snake Bothrops asper (terciopelo)." Toxicon 33(1): 19-29.

Heluany, N. F., B.-M. I. Homsi, J. R. Giglio, F.-J. Prado and S.-L. Rodrigues (1992). "Effects induced by bothropstoxin, a component from Bothrops jararacussu snake venom, on mouse and chick muscle preparations." Toxicon 30(10): 1203-10.

Kouyoumdjian, J. A. and C. Polizelli (1989). "[Snake bites by Bothrops moojeni: correlation of the clinical picture with the snake size]." Rev-Inst-Med-Trop-Sao-Paulo 31(2): 84-90.

Lomonte, B. and E. Carmona (1992). "Individual expression patterns of myotoxin isoforms in the venom of the snake Bothrops asper." Comp-Biochem-Physiol-B 102(2): 325-9.

Mancuso, L. C., M. M. Correa, C. A. Vieira, O. A. Cunha, J. J. Lachat, A.-H. S. de, C. L. Ownby and J. R. Giglio (1995). "Fractionation of Bothrops pirajai snake venom: isolation and characterization of piratoxin-I, a new myotoxic protein." Toxicon 33(5): 615-26.

Maruyama, M., A. S. Kamiguti, S. C. Tomy, L. C. Antonio, M. Sugiki and H. Mihara (1992). "Prothrombin and factor X activating properties of Bothrops erythromelas venom." Ann-Trop-Med-Parasitol 86(5): 549-56.

Maruyama, M., M. Sugiki, E. Yoshida, K. Shimaya and H. Mihara (1992). "Broad substrate specificity of snake venom fibrinolytic enzymes: possible role in haemorrhage." Toxicon 30(11): 1387-97.

Mendez, M. C. and C.-F. Riet (1995). "Snakebite in sheep." Vet-Hum-Toxicol 37(1): 62-3.

Nishida, S., Y. Fujimura, S. Miura, Y. Ozaki, Y. Usami, M. Suzuki, K. Titani, E. Yoshida, M. Sugimoto, A. Yoshioka and et al. (1994). "Purification and characterization of bothrombin, a fibrinogen- clotting serine protease from the venom of Bothrops jararaca." Biochemistry 33(7): 1843-9.

Paine, M. J., H. P. Desmond, R. D. Theakston and J. M. Crampton (1992). "Purification, cloning, and molecular characterization of a high molecular weight hemorrhagic metalloprotease, jararhagin, from Bothrops jararaca venom. Insights into the disintegrin gene family." J-Biol-Chem 267(32): 22869-76.

Pessatti, M., J. D. Fontana, M. F. Furtado, M. F. Guimaraes, L. R. Zanette, W. T. Costa and M. Baron (1995). "Screening of Bothrops snake venoms for L-amino acid oxidase activity [published erratum appears in Appl Biochem Biotechnol 1995 Dec;55(3):276]." Appl Biochem Biotechnol 55(3): 276.

Reichl, A. P. and F. R. Mandelbaum (1993). "Proteolytic specificity of moojeni protease A isolated from the venom of Bothrops moojeni." Toxicon 31(2): 187-94.

Reichl, A. P., S. M. Serrano, C. A. Sampaio and F. R. Mandelbaum (1993). "Hydrolytic specificity of three basic proteinases isolated from the venom of Bothrops moojeni for the B-chain of oxidized insulin." Toxicon 31(11): 1479-82.

Ribeiro, L. A. and M. T. Jorge (1989). "[Changes in blood coagulation time in patients bitten by young and adult Bothrops jararaca snakes]." Rev-Hosp-Clin-Fac-Med-Sao-Paulo 44(4): 143- 5.

Rojas, G., J. M. Guti'errez, J. A. Gen'e, M. G'Omez and L. Cerdas (1987). "[Neutralization of toxic and enzyme activities of 4 venoms from snakes of Guatemala and Honduras by the polyvalent antivenin produced in Costa Rica]." Rev-Biol-Trop 35(1): 59-67.

Rucavado, A., G. Borkow, M. Ovadia and J. M. Guti'errez (1995). "Immunological studies on BaH1 and BaP1, two hemorrhagic metalloproteinases from the venom of the snake Bothrops asper." Toxicon 33(8): 1103-6.

Serrano, S. M., R. Mentele, C. A. Sampaio and E. Fink (1995). "Purification, characterization, and amino acid sequence of a serine proteinase, PA-BJ, with platelet-aggregating activity from the venom of Bothrops jararaca." Biochemistry 34(21): 7186-93.

Serrano, S. M., C. A. Sampaio and F. R. Mandelbaum (1993). "Basic proteinases from Bothrops moojeni (caissaca) venom--II. Isolation of the metalloproteinase MPB. Comparison of the proteolytic activity on natural substrates by MPB, MSP 1 and MSP 2." Toxicon 31(4): 483-92.

Silveira, A. M., A. Magalhaes, C. R. Diniz and O.-E. B. de (1989). "Purification and properties of the thrombin-like enzyme from the venom of Lachesis muta muta." Int-J-Biochem 21(8): 863-71.

Tanigawa, M., M. Maruyama, M. Sugiki, K. Shimaya, K. Anai and H. Mihara (1994). "Clearance and distribution of a haemorrhagic factor purified from Bothrops jararaca venom in mice." Toxicon 32(5): 583-93.

Usami, Y., Y. Fujimura, S. Miura, H. Shima, E. Yoshida, A. Yoshioka, K. Hirano, M. Suzuki and K. Titani (1994). "A 28 kDa-protein with disintegrin-like structure (jararhagin-C) purified from Bothrops jararaca venom inhibits collagen- and ADP-induced platelet aggregation." Biochem-Biophys-Res-Commun 201(1): 331-9.

Zingali, R. B., P.-M. Jandrot, M. C. Guillin and C. Bon (1993). "Bothrojaracin, a new thrombin inhibitor isolated from Bothrops jararaca venom: characterization and mechanism of thrombin inhibition." Biochemistry 32(40): 10794-802.