Vera Lucia Pereira dos Santos

Experimental evidence for a direct cytotoxicity of Loxosceles intermedia (brown spider) venom in renal tissue

Brown spider (Loxosceles genus) venom causes necrotic lesions often accompanied by fever, hemolysis, thrombocytopenia, and acute renal failure. Using mice exposed to Loxosceles intermedia venom, we aimed to show whether the venom directly induces renal damage. The experimental groups were composed of 50 mice as controls and 50 mice that received the venom. Light microscopic analysis of renal biopsy specimens showed alterations including hyalinization of proximal and distal tubules, erythrocytes in Bowmans space, glomerular collapse, tubule epithelial cell blebs and vacuoles, interstitial edema, and deposition of eosinophilic material in the tubule lumen. Electron microscopic findings indicated changes including glomerular epithelial and endothelial cell cytotoxicity as well as disorders of the basement membrane. Tubule alterations include epithelial cell cytotoxicity with cytoplasmic membrane blebs, mitochondrial changes, increase in smooth endoplasmic reticulum, presence of autophagosomes, and deposits of amorphous material in the tubules. We also found that the venom caused azotemia with elevation of blood urea levels but did not decrease C3 complement concentration or cause hemolysis in vivo. Confocal microscopy with antibodies against venom proteins showed direct binding of toxins to renal structures, confirmed by competition assays. Double-staining immunofluorescence reactions with antibodies against type IV collagen or laminin, antibodies to venom toxins, and fluorescent cytochemistry with DAPI revealed deposition of toxins in glomerular and tubule epithelial cells and in renal basement membranes. Two-dimensional electrophoresis showed venom rich in low molecular mass and cationic toxins. By immunoblotting with antibodies to venom toxins on renal extracts from venom-treated mice, we detected a renal binding toxin at 30 kD. The data provide experimental evidence that L. intermedia venom is directly involved in nephrotoxicity.

Anatomical Characters of Leave and Stem of Calea serrata Less., Asteraceae

The genus Calea belongs to the tribe Heliantheae and presents about 125 species. Calea serrata, popularly known as erva-de-cobra, cha-amargo and quebra-tudo, is an endemic species found in southern Brazil and is used in traditional medicine to treat ulcers and livers problems. The present work aimed to study the pharmacobotanical characters of leaves and stems of C. serrata for quality control purposes. The plant material was processed according to standard methods of light and scanning electron microscopy. Glandular capitate-stalked and capitate-sessile, uniseriate multicellular non-glandular trichome with tapered apical cell, conical non-glandular trichome, isobilateral mesophyll, secretory ducts near the endoderm and circular shape with six ribs in the stem were important characters, which contributed to the identification of the species.