Renal- and calcium-dependent vascular effects of Polybia paulista wasp venom

In the present study, the effects of Polybia paulista venom (PPV) on renal and vascular tissues were investigated. Isolated kidneys perfused with PPV (1 and 3 μg/mL) had increased perfusion pressure, renal vascular resistance, urinary flow, and glomerular filtration rate; and reduced sodium tubular transport. Histological evaluation demonstrated deposits of proteins in Bowman's space and tubular lumen, and focal areas of necrosis. The venom promoted a cytotoxic effect on Madin-Darby canine kidney (MDCK) cells. A significant increase in lactic dehydrogenase levels was observed in response to venom exposure. In isolated mesenteric vascular beds, pressure and vascular resistance augmented in a dose-dependent manner. PPV increased the contractility of aortic rings maintained under basal tension. This contractile response was inhibited when preparations were maintained in Ca2+-free medium. Likewise, verapamil, a voltage-gated calcium channel blocker, also inhibited the contractile response. In this study, phentolamine, a blocker of α-adrenergic receptor blocker, significantly reduced the contractile effect of PPV in the aortic ring. In conclusion, PPV produced nephrotoxicity, which suggests a direct effect on necrotic cellular death in renal tubule cells. The vascular contractile effect of PPV appears to involve calcium influx through voltage-gated calcium channels via adrenergic regulation

Unexpected high diversity of galling insects in the Amazonian upper canopy: The savanna out there

A relatively large number of studies reassert the strong relationship between galling insect diversity and extreme hydric and thermal status in some habitats, and an overall pattern of a greater number of galling species in the understory of scleromorphic vegetation. We compared galling insect diversity in the forest canopy and its relationship with tree richness among upland terra firme, várzea, and igapó floodplains in Amazonia, Brazil. The soils of these forest types have highly different hydric and nutritional status. Overall, we examined the upper layer of 1,091 tree crowns. Galling species richness and abundance were higher in terra firme forests compared to várzea and igapó forests. GLM-ANCOVA models revealed that the number of tree species sampled in each forest type was determinant in the gall-forming insect diversity. The ratio between galling insect richness and number of tree species sampled (GIR/TSS ratio) was higher in the terra firme forest and in seasonally flooded igapó, while the várzea presented the lowest GIR/TSS ratio. In this study, we recorded unprecedented values of galling species diversity and abundance per sampling point. The GIR/TSS ratio from várzea was approximately 2.5 times higher than the highest value of this ratio ever reported in the literature. Based on this fact, we ascertained that várzea and igapó floodplain forests (with lower GIA and GIR), together with the speciose terra firme galling community emerge as the gall diversity apex landscape among all biogeographic regions already investigated. Contrary to expectation, our results also support the "harsh environment hypothesis", and unveil the Amazonian upper canopy as similar to vegetation habitats, hygrothermically stressed environments with temperature at lethal limits and high levels of leaf sclerophylly. © 2014 Julião et al

Follow-up of sickle cell disease patients with priapism treated by hydroxyurea

Hydroxyurea is one of the most successfully used therapies for sickle cell disease. Results of many clinical trials point to hydroxyurea administration for patients with frequent painful crises and acute chest syndrome. Priapism is one of the complications that could be prevented by hydroxyurea, but there are few reports demonstrating the results. Since November 1993, hydroxyurea has been used in our clinic for preventing priapism in patients with stuttering or major attacks who are still capable of achieving intercourse on demand. Five patients were enrolled in the study, and 4 cases benefited by this treatment. After the initial treatment for the acute attack, all five patients developed stuttering priapism. Hydroxyurea was then introduced at the initial dose of 10 mg/kg, and as the hydroxyurea dosage increased, the number or length of priapism episodes decreased. One to two months after the maximal dose (20-35 mg/kg) was introduced, the episodes disappeared. In two patients, we were forced to administer over 30 mg hydroxyurea/kg to abort the episodes, and, in another patient, 25 mg/kg was necessary. All patients present normal sexual activity. Hydroxyurea was discontinued in two patients, but stuttering priapism reappeared. Hydroxyurea was then re-introduced, and priapism disappeared. One patient, using 20 mg hydroxyurea/kg, had a 6-year remission of priapism after hydroxyurea administration; however, he experienced stuttering priapism, 1 month before a major attack, that progressed to impotence. During that month, he did not seek medical attention. In conclusion, the data here presented suggests that hydroxyurea may prevent priapism attacks in sickle cell disease, probably at higher doses than usually prescribed for painful crisis prevention. (C) 2004 Wiley-Liss, Inc.771454