Corticotropin-releasing hormone-like immunoreactivity inthe brain of the snake Bothrops jararaca

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.

Corticotropin-releasing hormone-like immunoreactivity in the brain of the snake Bothrops jararaca.

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.

Bites by the colubrid snake Philodryas olfersii: a clinical and epidemiological study of 43 cases.

Less than 10 cases of bites by Philodryas olfersii (Colubridae) have been reported in the literature. In this study, 43 patients admitted to the Instituto Butantan, São Paulo, Brazil, with the diagnosis of P. olfersii bite from 1982 to 1990 were reviewed. The 32 male (74.4%) and 11 female (25.6%) patients presented mainly from November to February (65%). The most common clinical features were local pain (37.2%), swelling (34.9%), erythema (18.6%) and ecchymosis (9.3%). The 20 minute whole blood clotting test was performed in 11 patients and in all of them the blood was coagulable. Most of the accidents occurred during the hottest months and during daylight hours. The most common bite site was the hands. Severe envenoming is not frequent in these accidents.

Cloning of an unusual natriuretic peptide from the South American coral snake Micrurus corallinus

In the course of cloning abundant cDNAs from the South American coral snake Micrurus corallinus venom gland, we characterized a cDNA coding for a putative natriuretic peptide. All the natural natriuretic peptides described so far, possess a ring structure composed of 17 amino acids formed through an S-S bridge which is extended at the N-terminus by few to several amino acids and may be extended at the C-terminus, usually 4-7 amino acids. In contrast, the M. corallinus natriuretic peptide presents several distinct features: (a) the preform of the deduced natriuretic peptide displays an unusual C-terminus extension. This implies that the mature peptide has a long C-terminal tail or it is further extensively processed to result in the mature natriuretic peptide with the expected 4-7 amino-acid extension. (b) the deduced natriuretic peptide presents an unusual internal Cys within the ring structure. This raises the possibility of natriuretic peptides with a smaller ring structure. (c) the putative natriuretic peptide is flanked by two homologous peptides of unknown function. In addition, an analogous peptide was synthesized and assayed on perfused rat kidney, showing a dose-dependent response in urinary volume and sodium excretion. Moreover, northern-blot studies showed that M. corallinus natriuretic peptide transcripts were highly expressed in venom glands, but they were not detectable in other tissues like heart and brain, suggesting a main role for this M. corallinus natriuretic peptide in the venom gland or in the envenomation by this coral snake's bite

Snake bites by the jararacuçu (Bothrops jararacussu): clinicopathological studies of 29 proven cases in São Paulo State, Brazil.

The jararacuçu, one of the most dreaded snakes of Brazil, southern Bolivia, Paraguay and northeastern Argentina, is a heavily-built pit viper which may grow to a length of 2.2 m. Up to 1000 mg (dry weight) of highly-lethal venom may be milked from its venom glands on a single occasion. It has accounted for 0.8% to 10% of series of snake bites in São Paulo State, Brazil. We examined 29 cases of proven jararacuçu bites recruited over a 20-year period in two São Paulo hospitals. Severe signs of local and systemic envenoming, (local necrosis, shock, spontaneous systemic bleeding, renal failure) were seen only in patients bitten by snakes longer than 50 cm; bites by shorter specimens were more likely to cause incoagulable blood. Fourteen patients developed coagulopathy, six local necrosis (requiring amputation in one) and five local abscesses. Two became shocked and four developed renal failure. Three patients, aged 3, 11 and 65 years, died 18.75, 27.75 and 83 h after being bitten, with respiratory and circulatory failure despite large doses of specific antivenom and intensive-care-unit management. In two patients, autopsies revealed acute renal tubular necrosis, cerebral oedema, haemorrhagic rhabdomyolysis at the site of the bite and disseminated intravascular coagulation. In one survivor with chronic renal failure, renal biopsy showed bilateral cortical necrosis; the patient remains dependent on haemodialysis. Effects of polyspecific Bothrops antivenom were not impressive, and it has been suggested that anti-Bothrops and anti-Crotalus antivenoms should be given in combination.

Cloning of an unusual natriuretic peptide from the South American coral snake Micrurus corallinus.

In the course of cloning abundant cDNAs from the South American coral snake Micrurus corallinus venom gland, we characterized a cDNA coding for a putative natriuretic peptide. All the natural natriuretic peptides described so far, possess a ring structure composed of 17 amino acids formed through an S-S bridge which is extended at the N-terminus by few to several amino acids and may be extended at the C-terminus, usually 4-7 amino acids. In contrast, the M. corallinus natriuretic peptide presents several distinct features: (a) the proform of the deduced natriuretic peptide displays an unusual C-terminus extension. This implies that the mature peptide has a long C-terminal tail or it is further extensively processed to result in the mature natriuretic peptide with the expected 4-7 amino-acid extension. (b) the deduced natriuretic peptide presents an unusual internal Cys within the ring structure. This raises the possibility of natriuretic peptides with a smaller ring structure. (c) the putative natriuretic peptide is flanked by two homologous peptides of unknown function. In addition, an analogous peptide was synthesized and assayed on perfused rat kidney, showing a dose-dependent response in urinary volume and sodium excretion. Moreover, northern-blot studies showed that M. corallinus natriuretic peptide transcripts were highly expressed in venom glands, but they were not detectable in other tissues like heart and brain, suggesting a main role for this M. corallinus natriuretic peptide in the venom gland or in the envenomation by this coral snake's bite.

Hemorrhagic, fibrinogenolytic and edema-forming activities of the venom of the colubrid snake Philodryas olfersii (green snake).

The venom of P. olfersii has high hemorrhagic, edema-inducing and fibrin(ogen)olytic activities. It is devoid of thrombin-like, procoagulant, phospholipase A2 and platelet aggregating enzymes. The main activities are metalloproteinases inhibited by metal chelators (EDTA and 1,10-phenanthroline) and sulfhydryl compounds (DTT and cysteine). The hemorrhagic and fibrinogenolytic enzymes were partially purified by gel filtration on HPLC. The hemorrhagic activity of the venom was neutralized by commercial horse antivenoms to Bothrops species, as well as by rabbit antisera specific for hemorrhagic factors isolated from these Bothrops venoms. No immunoprecipitin reactions were obtained, indicating that the few epitopes of the P. olfersii hemorrhagin are involved in these neutralization reactions. The fibrinogenolytic enzyme cleaves A alpha-chain more quickly than the B beta-chain of human fibrinogen. The venom also solubilizes fibrin. This solubilization appears to occur from the hydrolysis of unpolymerized alpha-chain and cross-linked gamma-gamma dimer. The fibrin peptide products are distinct from those produced by plasmin.