Venomics profiling of Thamnodynastes strigatus unveils matrix metalloproteinases and other novel proteins recruited to the toxin arsenal of rear-fanged snakes.

Rear-fanged and aglyphous snakes are usually considered not dangerous to humans because of their limited capacity of injecting venom. Therefore, only a few studies have been dedicated to characterizing the venom of the largest parcel of snake fauna. Here, we investigated the venom proteome of the rear-fanged snake Thamnodynastes strigatus , in combination with a transcriptomic evaluation of the venom gland. About 60% of all transcripts code for putative venom components. A striking finding is that the most abundant type of transcript (∼47%) and also the major protein type in the venom correspond to a new kind of matrix metalloproteinase (MMP) that is unrelated to the classical snake venom metalloproteinases found in all snake families. These enzymes were recently suggested as possible venom components, and we show here that they are proteolytically active and probably recruited to venom from a MMP-9 ancestor. Other unusual proteins were suggested to be venom components: a protein related to lactadherin and an EGF repeat-containing transcript. Despite these unusual molecules, seven toxin classes commonly found in typical venomous snakes are also present in the venom. These results support the evidence that the arsenals of these snakes are very diverse and harbor new types of biologically important molecules.

Maintenance of venomous snakes in captivity for venom production at Butantan Institute from 1908 to the present: a scoping history.

Maintenance of snakes at Butantan Institute started in the last century, intending to produce a different antivenom serum to reduce death caused by snakebites. Through a successful campaign coordinated by Vital Brazil, farmers sent venomous snakes to Butantan Institute by the railway lines with no cost. From 1908 to 1962, the snakes were kept in an outdoor serpentarium, where venom extraction was performed every 15 days. During this period, the snake average survival was 15 days. In 1963, the snakes were transferred to an adapted building, currently called Laboratory of Herpetology (LH), to be maintained in an intensive system. Although the periodicity of venom extraction remained the same, animal average survival increased to two months. With the severe serum crisis in 1983, the Ministry of Health financed remodeling for the three public antivenom producers, and with this support, the LH could be improved. Air conditioning and exhausting systems were installed in the rooms, besides the settlement of critical hygienic-sanitary managements to increase the welfare of snakes. In the early 1990s, snake survival was ten months. Over the years to the present day, several improvements have been made in the intensive serpentarium, as the establishment of two quarantines, feeding with thawed rodents, an interval of two months between venom extraction routines, and monitoring of snake health through laboratory tests. With these new protocols, average snake survival increased significantly, being eight years for the genus Bothrops, ten years for genus Crotalus and Lachesis, and four years for the genus Micrurus. Aiming the production of venoms of good quality, respect for good management practices is essential for the maintenance of snakes in captivity. New techniques and efficient management must always be sought to improve animal welfare, the quality of the venom produced, and the safety of those working directly with the venomous snakes.

Interspecific variation in venom composition and toxicity of Brazilian snakes from Bothrops genus.

The genus Bothrops spp. is responsible for 90% of envenomation by snakes in Brazil, and the standard treatment for snakebites is the antivenom therapy. The anti-bothropic serum produced by Butantan Institute is prepared by the hyperimmunization of horses with a pool of venoms from Bothrops alternatus, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni and Bothrops neuwiedi. In this study, the biochemical and biological characteristics of the venoms from nineteen snakes of the genus Bothrops, responsible for human accidents in Brazil, were analysed. Venoms, particularly from Crotalidae and Viperidae snakes, are rich sources of serine proteases and metalloproteases and the ability of the Brazilian anti-bothropic serum to neutralize the proteolytic activity of these venoms were also tested. The results obtained here show the existence of a large range of variation in the composition and activities in Bothrops spp. toxins and demonstrate that the anti-bothropic serum is not able to fully neutralize the toxic activities of all analysed venoms. These suggest that for the preparation of a fully effective therapeutic anti-bothropic serum, other venoms should be included in the immunization mixture.

Duvernoy's gland secretion of Philodryas olfersii and Philodryas patagoniensis (Colubridae): neutralization of local and systemic effects by commercial bothropic antivenom (Bothrops genus).

Colubrids involved in human envenomation in Brazil are mainly from the genera Helicops, Oxyrhopus, Thamnodynastes and Philodryas. There is a relatively large number of clinical descriptions involving the Xenodontinae snakes, Philodryas olfersii and Philodryas patagoniensis, in human accidents. The most common manifestations of envenomation are local pain, swelling, erythema and ecchymosis and regional lymphadenopathy with normal coagulation. The aims of this study were to characterize the biochemical and biological properties of P. olfersii and P. patagoniensis venoms, and to investigate their immunological cross-reactivities by using both specific antisera and anti-Bothrops sp serum used for human serum therapy in Brazil, in neutralizing the lethal and hemorrhagic effects of these venoms. We show here that P. olfersii e P. patagoniensis venoms present proteolytic and haemorrhagic activities but are devoid of phospholipase A2 activity. Haemorrhage and lethality induced by P. olfersii and P. patagoniensis are associated with metal-dependent proteinases, since EDTA could block these toxic activities. P. olfersii and P. patagoniensis venoms were immunogenic and the antisera produced were able to recognize several bands in P. olfersii, P. patagoniensis venoms in Bothrops jararaca venom.

Maintenance of venomous snakes in captivity for venom production at Butantan Institute from 1908 to the present: a scoping history

Maintenance of snakes at Butantan Institute started in the last century, intending to produce a different antivenom serum to reduce death caused by snakebites. Through a successful campaign coordinated by Vital Brazil, farmers sent venomous snakes to Butantan Institute by the railway lines with no cost. From 1908 to 1962, the snakes were kept in an outdoor serpentarium, where venom extraction was performed every 15 days. During this period, the snake average survival was 15 days. In 1963, the snakes were transferred to an adapted building, currently called Laboratory of Herpetology (LH), to be maintained in an intensive system. Although the periodicity of venom extraction remained the same, animal average survival increased to two months. With the severe serum crisis in 1983, the Ministry of Health financed remodeling for the three public antivenom producers, and with this support, the LH could be improved. Air conditioning and exhausting systems were installed in the rooms, besides the settlement of critical hygienic-sanitary managements to increase the welfare of snakes. In the early 1990s, snake survival was ten months. Over the years to the present day, several improvements have been made in the intensive serpentarium, as the establishment of two quarantines, feeding with thawed rodents, an interval of two months between venom extraction routines, and monitoring of snake health through laboratory tests. With these new protocols, average snake survival increased significantly, being eight years for the genus Bothrops, ten years for genus Crotalus and Lachesis, and four years for the genus Micrurus. Aiming the production of venoms of good quality, respect for good management practices is essential for the maintenance of snakes in captivity. New techniques and efficient management must always be sought to improve animal welfare, the quality of the venom produced, and the safety of those working directly with the venomous snakes.(AU)

Diversity of Micrurus snake species related to their venom toxic effects and the prospective of antivenom neutralization.

BACKGROUND: Micrurus snake bites can cause death by muscle paralysis and respiratory arrest, few hours after envenomation. The specific treatment for coral snake envenomation is the intravenous application of heterologous antivenom and, in Brazil, it is produced by horse immunization with a mixture of M. corallinus and M. frontalis venoms, snakes that inhabit the South and Southeastern regions of the country. However, this antivenom might be inefficient, considering the existence of intra- and inter-specific variations in the composition of the venoms. Therefore, the aim of the present study was to investigate the toxic properties of venoms from nine species of Micrurus: eight present in different geographic regions of Brazil (M. frontalis, M. corallinus, M. hemprichii, M. spixii, M. altirostris, M. surinamensis, M. ibiboboca, M. lemniscatus) and one (M. fulvius) with large distribution in Southeastern United States and Mexico. This study also analyzed the antigenic cross-reactivity and the neutralizing potential of the Brazilian coral snake antivenom against these Micrurus venoms. METHODOLOGY/PRINCIPAL FINDINGS: Analysis of protein composition and toxicity revealed a large diversity of venoms from the nine Micrurus species. ELISA and Western blot assays showed a varied capability of the therapeutic antivenom to recognize the diverse species venom components. In vivo and in vitro neutralization assays indicated that the antivenom is not able to fully neutralize the toxic activities of all venoms. CONCLUSION: These results indicate the existence of a large range of both qualitative and quantitative variations in Micrurus venoms, probably reflecting the adaptation of the snakes from this genus to vastly dissimilar habitats. The data also show that the antivenom used for human therapy in Brazil is not fully able to neutralize the main toxic activities present in the venoms from all Micrurus species occurring in the country. It suggests that modifications in the immunization scheme, with the inclusion of other venoms in the antigenic mixture, should occur in order to generate effective therapeutic coral snake antivenom.

Human complement activation and anaphylatoxins generation induced by snake venom toxins from Bothrops genus.

Snake venoms are a complex mixture of components, which have a wide range of actions both on prey and human victims. The genus Bothrops causes the vast majority of snakebites in Central and South America, being responsible for 80% of snake envenomations in Brazil. Envenomations are characterized by prominent local effects, including oedema, haemorrhage and necrosis, which can lead to permanent disability. Systemic manifestations such as haemorrhage, coagulopathy, shock and acute renal failure may also occur. In the present study we have investigated the action of venoms from 19 species of snakes from the genus Bothrops, occurring in Brazil, on the complement system in in vitro studies. All venoms were able to activate the classical complement pathway, in the absence of sensitizing antibody. This activation was in part associated with the cleavage of C1-Inhibitor by proteases present in these venoms, which disrupts complement activation control. No modification of the membrane bound complement regulators, such as DAF, CR1 and CD59 was detected, after treatment of human erythrocytes with the snake venoms. Some of the Bothrops venoms were also able to activate alternative and lectin pathways, as measured in haemolytic and ELISA assays. C3a, C4a and C5a were generated in sera treated with the venoms, not only through C-activation, but also by the direct cleavage of complement components, as determined using purified C3 and C4. Metallo- and/or serine-protease inhibitors prevented cleavage of C3 and C4. These results suggest that Bothrops venoms can activate the complement system, generating a large amount of anaphylatoxins, which may play an important role in the inflammatory process presented in humans after snake envenomations, and they may also assist, due to their vasodilatory effects, to enhance the spreading of other venom components.

Antigenic cross-reactivity and immunogenicity of Bothrops venoms from snakes of the Amazon region.

Snakebites are still a critical public health problem in developing countries or isolated areas. In Brazil, the North Region has a high distribution coefficient worsened by the significant number of eventually unreported cases, due to difficulties in access to health services, to the natural geographic barriers and the vast territory. In the Rio Negro area, the species Bothrops atrox, Bothrops brazili, Lachesis muta muta and Bothriopsis taeniata are thought to be the major species responsible for snakebites. The aim of this study was to qualitatively and quantitatively determine the antigenic cross-reactivity and expression of toxins and the immunogenicity of Bothrops venom species of the Amazon and to evaluate the general efficacy of the therapeutic sera. The in vivo assays demonstrated that the defibrinating activity of B. taeniata venom was absent but that the lethal and hemorrhagic properties were more intense than in the B. atrox venom. The results evidence venom variability among the two B. atrox populations from two distinct Amazonian regions, which may reveal a subjacent speciation process. The results point to new aspects that may guide the improvement of anti-Bothropic therapeutic serum.

Neurotoxicity of Micrurus altirostris (Uruguayan coral snake) venom and its neutralization by commercial coral snake antivenom and specific antiserum raised in rabbits.

In this work, we studied the neuromuscular blockade caused by Micrurus altirostris venom (0.1-10 microg/mL) in indirect stimulated chick biventer cervicis and mouse phrenic nerve-diaphragm preparations and the ability of commercial antivenom (Instituto Butantan) and antiserum raised in rabbits to neutralize neurotoxicity and lethality in chicks and mice (LD(50) 0.042 and 0.255 mg/kg), injected i.m. and i.p., respectively, with venom (5 LD(50)):antivenom or antiserum mixtures (n = 6) of 1:1-1:2.5-1:5-1:10-1:20. The venom caused a complete and irreversible neuromuscular blockade in both preparations, inhibited the acetylcholine and carbachol contractures, without interfering on KCl response. The neuromuscular blockade was not Ca(2+) or temperature-dependent and did not affect the response to direct stimulation. Only a venom:antivenom or antiserum ratio of 1:20 neutralized the neuromuscular blockade in vitro and protected chicks and mice against 5 LD(50) of venom. Our results indicated that Micrurus altirostris venom interferes with postsynaptic neurotransmission and that commercial antivenom and rabbit antiserum have low efficacy in neutralizing the neurotoxicity and lethality of this venom.

Neuromuscular and phospholipase activities of venoms from three subspecies of Bothrops neuwiedi (B. n. goyazensis, B. n. paranaensis and B. n. diporus).

The Bothrops neuwiedi (Neuwied's lancehead) species complex consists of a variety of subspecies with a wide distribution in South America. In this work, we compared the neuromuscular blockade caused by venoms from three subspecies (B. n. goyazensis, B. n. paranaensis and B. n. diporus) of this complex using chick biventer cervicis (BC) and mouse phrenic nerve-diaphragm (PND) preparations and investigated their phospholipase A2 (PLA2) activities and electrophoretic profiles. The order of potency of PLA2 activity was B. n. diporus>B. n. paranaensis>B. n. goyazensis. In BC preparations, B. n. goyazensis venom (50 microg/mL) was significantly (p<0.05) more active than B. n. paranaensis and B. n. diporus venoms, which did not produce a significant blockade at this time interval; after 120 min, B. n. goyazensis, B. n. paranaensis and B. n. diporus venoms (100 microg/mL) produced blockades of 57.4+/-5%, 30+/-3% and 17.4+/-7% (n=3-6 each), respectively. The three venoms inhibited contractures in response to ACh, indicating interference with postsynaptic neurotransmission. Only B. n. goyazensis and B. n. paranaensis venoms caused a long-lasting, concentration-dependent muscle contracture prior to blockade. In PND preparations, all of the venoms blocked the twitch-tension responses within 45-100 min, indicating that these preparations were more sensitive than avian preparations. There was a correlation between PLA2 activity and the time for 50% blockade in PND but not in BC preparations. SDS-PAGE showed quantitative rather than qualitative differences among the venoms. These results indicate that the venoms of the three subspecies had similar profiles of neuromuscular activity, although the relationship with PLA2 activity varied with the preparation used.

Influência das alterações ambientais na epidemiologia dos acidentes ofídicos e na distribuição geográfica das serpentes de importância médica nos estados de São Paulo e Paraná: (Nota Prévia) / Influence of environmental changes in the epidemiology of snakebites and geographical distribution of snakes of medical importance in São Paulo and Paraná States, 1988-1997

BACKGROUND: Geographical distribution of snakebites and snakes of medical importance has a strong correlation with changes in the vegetation cover as a consequence of the expansion of agricultural frontiers. In São Paulo (SP) and Paraná (PR) the process of land occupation has led to a radical transformation in the natural landscape. The objective of this study was to analyze a historical series of snakebites and the geographical distribution of the main species of snakes, taking into account environmental changes of the landscape. MATERIAL AND METHODS: An observational study was conducted. A historical series (1988-1997) of snakebites was obtained from the notification records sent to the Health Secretaries of São Paulo (SP) and Paraná (PR) States. Registries of the herpetological collections were obtained from the Butantan Institute (SP), the Natural History Museum (PR) and from the Production and Research Center in Immunebiologics (PR). Data regarding vegetation cover and percentage of land occupation with the main agricultural practices were analyzed by the Pearson correlation coefficient. The sites of snakebites occurrence and capture of snakes were identified at the municipality level. Maps were obtained using a geographical information system using the software ArqView v.3.0. RESULTS: From the Bothrops species, B. jararaca showed a wide distribution in open fields, forests, and even in regions under anthropic influence, while B. moojeni and B. neuwiedi were found predominantly in open fields. Crotalus occupied areas originally constituted by semidecidual estacional forest and "cerrado". The annual incidence of snakebites varied from 4.31 to 10.57 cases per 100,000 population, decreasing through the period for both Bothrops (88%) and Crotalus (11%). Micrurus accidents were rare (1%) in São Paulo and absent in Paraná. The areas of greater risk for snakebites were coincident with the snakes distribution areas: the administrative regions of Registro and Sorocaba, in São Paulo, and União da Vitória, in Paraná, for Bothrops accidents, and Bauru and Presidente Prudente in Sao Paulo, Cascavel and Ivaiporã in Paraná, for Crotalus accidents. No correlation between snake distribution and vegetation cover was observed, except for B. jararacussu in the remaining forest at the Vale do Ribeira. No correlation was observed between land occupation and Bothrops snakebites. A small negative correlation was observed between Crotalus accidents and areas with sugar cane. CONCLUSIONS: A decreasing tendency was observed in the number of snakebites and snakes of medical importance. Maps of the distribution of poisonous snakes and snakebites allowed a better definition of risk areas. The anthropic pressure probably had influence on the result of no correlation between areas of distribution of snakes with the vegetation cover, while some agricultural practices may had resulted in changes in the risk areas for snakebites.

DELINEAMENTO DO PROBLEMA: A distribuição geográfica dos acidentes ofídicos e das serpentes de interesse médico guarda estreita correlação com as mudanças na cobertura vegetal, decorrentes da expansão de fronteiras agrícolas, notadamente em São Paulo (SP) e Paraná (PR), onde o processo de ocupação da terra levou a uma transformação radical da paisagem natural. O objetivo deste trabalho foi realizar levantamento de série histórica sobre a ocorrência de acidentes e a distribuição das espécies de serpentes, levando em conta as alterações ocorridas na cobertura vegetal. MATERIAL E MÉTODOS: Foi realizado levantamento de série história (1988-1997) dos acidentes ofídicos, a partir das fichas de notificação encaminhadas às Secretarias de Estado da Saúde do Paraná e São Paulo e registro das coleções herpetológicas do Instituto Butantan (SP), Museu de História Natural (PR) e Centro de Produção e Pesquisa em Imunobiológicos (PR). Dados sobre cobertura vegetal e percentual de ocupação do solo das principais práticas agrícolas foram correlacionados, utilizando-se o coeficiente de correlação de Pearson. As localidades de ocorrência dos acidentes e de coleta das serpentes foram identificadas por município. Foram obtidos mapas, por meio de um sistema de informação geográfica, no programa ArqView versão 3.0. RESULTADOS: Das espécies de Bothrops, a B. jararaca mostrou ampla distribuição em formações abertas, florestas e até regiões sob influência antrópica, enquanto que B. moojeni e B. neuwiedi foram encontradas em formações abertas. As Crotalus ocuparam áreas originalmente formadas por floresta estacional semidecidual e cerrado. A incidência anual dos acidentes ofídicos variou de 4,31 a 10,57 casos por cem mil habitantes, com queda ao longo do período, tanto dos acidentes botrópicos (88%) como dos crotálicos (11%). Os acidentes elapídicos foram raros (1%) em São Paulo e ausentes no Paraná. As áreas de maior risco para os acidentes foram coincidentes com as áreas de distribuição das serpentes, destacando-se, para os acidentes botrópicos, as regiões administrativas de Registro e Sorocaba em São Paulo e União da Vitória no sul do Paraná e, para os acidentes crotálicos, Bauru e Presidente Prudente em São Paulo, Cascavel e Ivaiporã no Paraná. Não houve relação entre áreas de ocorrência de serpentes e cobertura vegetal atual, com exceção da sobreposição de B. jararacussu nos remanescentes de mata no Vale do Ribeira. Não se observou correlação entre ocupação do solo e acidentes botrópicos, havendo, nos acidentes crotálicos, pequena correlação negativa com a ocupação por cana-de-açúcar. CONCLUSÕES: Observou-se tendência de queda no número de acidentes ofídicos e de serpentes de importância médica. Mapas de distribuição de serpentes peçonhentas e de acidentes ofídicos permitiram melhor definição das áreas de risco. A influência antrópica provavelmente influenciou a não-correlação com a cobertura vegetal atual, enquanto que práticas agrícolas podem ter determinado deslocamento nas áreas de maior risco de acidentes.

Influências sazonal e do processo de extraçäo sobre a produçäo, toxicidade do veneno e sobrevida de Bothrops Jararaca (Wied, 1824) / Seasonable influences and process of extraction about production, venom's toxicity and Bothrops Jararaca's surviving (Wied, 1824)

Foram utilizadas, no presente trabalho, 240 serpentes da espécie Bothrops jararaca: 120 animais foram estudados durante o inverno e 120, durante o veräo. Estes grupos foram submetidos a diferentes tratamentos: 60 serpentes tiveram seus venenos extraídos, numa sequência de quatro operaçöes, pelo processo elétrico, e 60, em igual número de extraçöes, pelo processo manual, no inverno. Outro grupo de 120 ofídios foram submetidos ao mesmo procedimento, porém no veräo. Verificaram que as maiores porcentagens de mortes após quatro extraçöes foram registradas no inverno pelo processo elétrico (35,59%). Quanto à produçäo do veneno, foi constatado que o maior rendimento ocorre no veräo pelo processo manual. A toxicidade foi aferida através da determinaçäo de DL50 em camundongos inoculados pela via intraperitoneal

Estudo comparativo entre os venenos de serpentes do gênero Bothrops, procedentes do Estado de Säo Paulo e do Estado do Paraná com algumas espécies morfologicamente duvidosas / Comparative study between snakes' venoms of Bothrops class, proceeding of Säo Paulo State and Paraná State with some species morphologic dubious

Os venenos de serpentes Bothrops moojeni, Bothrops neuwied e Bothrops jararacussu procedentes do Estado de Säo Paulo, foram comparados com os venenos das mesmas espécies procedentes da regiäo de Itaipú, Estado do Paraná e de alguns exemplares de serpentes de Itaipú com características morfológicas entre B. moojeni e B. neuwiedi e entre B. moojeni e B. jararacussu. Os parâmetros analisados foram: letalidade, eletroforese em gel de poliacrilamina com SDS, imunodifusäo e imunoeletroforese. Os valores da DL50 dos venenos das espécies B. moojeni e B. neuwiedi, näo apresentam diferenças significativas quanto à letalidade; contudo, os venenos de B. jararacussu apresentam diferenças, sendo que os espécimes de Säo Paulo possuem letalidade mais elevada em relaçäo aos de Itaipu. Os venenos de B. moojeni e B. neuwied procedentes das duas regioes näo apresentaram variaçöes em seus padröes eletroforéticos, já os venenos de B. jararacussu apresentaram algumas diferenças nos eletroferogramas. Os exemplares de serpentes de Itaipu com características morfológicas entre B. moojeni e B. neuwiedi (Bothrops sp1) e entre B. moojeni e B. jararacussu (Bothrops sp2), quanto ao perfil eletroforético, assemelham-se ao veneno da espécie B. moojeni. A análise dos componentes imunogênicos dos venenos das três espécies, através das técnicas de imunodifusäo e imunoeletroforese, näo apresentam variaçöes apreciáveis

Controle de qualidade dos venenos animais e dos correspondentes antivenenos: I. Padronizaçäo dos métodos de ensaio das atividades bioquímicas e farmacológicas dos venenos de algumas espécies do gênero Bothrops e Crotalus ... / Quality control of animal venoms and of their correspondent antivenoms: I. Standardization of the assay methods to analise the biochemical and pharmacological properties of venoms from some snakes belonging to the genus Bothrops and Crotalus...

Para a avaliaçäo das atividades promotoras da coagulaçäo do fibrinogênio e do plasma e indutoras de edema, hemorragia, necrose e mortalidade presentes no veneno de algumas serpentes brasileiras (B.alternatus, B.atrox, B.cotiara, B.jararaca, B.jararacussu, B.moojeni, B.neuwiedi e crotalus durissus terrificus) foram padronizados métodos de ensaio. De cada espécie de serpente foram preparadas misturas homogêneas de venenos, o teor protéico determinado pelo método de Lowry et al.(6) e cada mistura dividida igualmente em duas amostras, uma sendo seca sob vácuo à temperatura ambiente (VS) e a outra liofilizada (VL), e ambas armazenadas a 20'C. O teor protéico foi da ordem de 1.0-1.5 mg/mg de veneno seco na maioria das espécies e da ordem de 0.8-0.85 mg/mg no veneno de B.cotiara. A atividade enzimática, medida pela proteólise da caseína, foi muito pronunciada nos venenos de B.atrox e B.moojeni, baixa no veneno de B.cotiara, intermediária no veneno das demais espécies do gênero Bothrops e praticamente indetectável no veneno de c.d.terrificus. As atividades hemorrágica e necrotizante, conquanto presentes no veneno de todas as espécies botrópicas, foram bastante elevadas no veneno de B.neuwied e ausentes no veneno de c.d.terrificus. Todos os venenos testados exibiram atividade edematogênica. A atividade promotora de coagulaçäo, embora presente em todos os venenos, foi mais alta nos venenos de B.atrox, B.cotiara e B. neuwiedi. A atividade letal, medida em termos de DL50, foi marcadamente elevada no veneno de c.d.terrificus e alta nos venenos de B.jararaca e B.neuwiedi em comparaçäo com os venenos das demais serpentes do gênero Bothrops. Em todos os ensaios as amostras de veneno VS e VL foram sempres testadas em paralelo. Conquanto as atividades enzimáticas e biológicas dos venenos näo se diferissem em ambas as amostras, o processo de liofilizaçäo deveria ser o método de escolha pelo fato de associar, durante o processo de secagem, congelaçäo e vácuo, condiçöes que presumivelmente preservariam melhor a configuraçäo molecular natural da maioria das proteínas

A computation program to analyse data obtained in quantal assays

É feita a descriçäo de um programa de computaçäo que permite a análise de dados obtidos na determinaçäo da potência de drogas que produzam efeitos do tipo tudo-ou nada, quando administradas a animais experimentais. O programa foi aplicado: a) para determinar as potências das preparaçöes de veneno botrópico e crotálico, as quais foram enviadas ao Ministério da Saúde como padröes para determinaçäo de potências de soros anti-peçonhentos neste país; b) para verificar se o dessecamento espontâneo de veneno botrópico a temperatura ambiente produz um decréscimo de sua potência letal; c) para determinar a potência letal do veneno de Bothrops erythromelas; e d) para comparar a sensibilidade ao veneno botrópico de duas linhagens de camundongos geneticamente selecionados