TLC and HPLC methods for the determination of plumbagin for the diagnosis of poisoning by Plumbago scandens L

Plumbago scandens L. (Plumbaginaceae) occurs in all regions of Brazil. It has been described as toxic to cattle and goats. Caustic lesions in the upper digestive tract characterize poisoning. P. scandens contains a naphthoquinone named plumbagin, which presents high cytotoxic activity. Plumbago auriculata Lam., a widely used ornamental plant, is considered potentially toxic, but there is limited data about its toxicity. This work aimed to validate analytical methodologies for determining the levels of plumbagin in samples of leaves, stems, and rumen content to be used as an auxiliary chemical marker in the laboratory diagnosis of intoxication. One methodology used thin layer chromatography (TLC), and another used high-performance liquid chromatography (HPLC). The presence of palisade grass (Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster), Guinea grass (Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs), corn silage, and rumen content did not interfere with plumbagin in the two methodologies. The TLC methodology generates qualitative results but is simple to implement and has a low cost. The HPLC methodology showed a limit of detection (LOD) of 0.01 μg/mL and a limit of quantification (LOQ) of 0.05 μg/mL. Leaf and stem samples of P. scandens evaluated showed high levels of plumbagin (0.261 ± 0.087 % and 0.327 ± 0.055 %, respectively). In contrast, leaves of P. auriculata did not show detectable levels of the toxin, and some stem samples showed low levels (up to 0.000114 %). Thus, these methodologies can be used to confirm or rule out the consumption of P. scandens in rumen content from animals suspected of poisoning.

Hepatic granulomas induced by Schistosoma mansoni in mice deficient for connexin 43 present lower cell proliferation and higher collagen content

Granuloma formation involves a coordinated interaction between monocytes and macrophages, epithelioid cells, lymphocytes, eosinophils, neutrophils and fibroblasts. It has been established that extracellular communication via cytokines is important for the assembly of granulomas. However, the importance of gap junctions and intercellular communication to granuloma formation and development had never been assessed. Connexins are proteins that form gap junctions, and connexin 43 (Cx43) is present in macrophages, lymphoid cells, myelogenous cells, fibroblasts and others. We analyzed the effect of heterologous deletion of Gja1 (Cx43 gene) on the formation and development of hepatic granulomas induced by Schistosoma mansoni eggs. Heterozygous (Cx43(+/-)) and wild-type (Cx43(+/+)) mice were infected subcutaneously with S. mansoni cercarie and evaluated after 6, 8 and 12 weeks. Granuloma cells express Cx43, as revealed by real-time PCR in isolated granulomas, and by immunohistochemistry. Cx43 expression was reduced in Cx43(+/-) mice, as expected. No differences in the average area of granulomas or number of cells per granuloma were observed between mice of different genotypes. However, granuloma cells from Cx43(+/-) mice displayed a reduced index of the proliferating cell nuclear antigen (PCNA) labeling at 8 and 12 weeks post-infection. Moreover, Cx43(+/-) granulomas unexpectedly presented a higher degree of fibrosis, quantified by morphometric analysis in Sirius Red-stained slides. Our results indicate that the deletion of one allele of the Cx43 gene, and possibly the reduced gap junction intercellular communication capacity (GJIC), may impair the interactions between granuloma cells, reducing their proliferation and increasing their collagen content, thereby modifying the characteristics of S. mansoni granuloma in mice.

Effects of peripheral-type benzodiazepine receptor ligands on Ehrlich tumor cell proliferation

Peripheral-type benzodiazepine receptors have been found throughout the body, and particularly, in high numbers, in neoplastic tissues such as the ovary, liver, colon, breast, prostate and brain cancer. Peripheral-type benzodiazepine receptor expression has been associated with tumor malignity, and its subcellular localization is important to define its function in tumor cells. We investigated the presence of peripheral-type benzodiazepine receptors in Ehrlich tumor cells, and the in vitro effects of peripheral-type benzodiazepine receptors ligands on tumor cell proliferation. Our results demonstrate the presence of peripheral-type benzodiazepine receptor in the nucleus of Ehrlich tumor cells (85.53+/-12.60%). They also show that diazepam and Ro5-4864 (peripheral-type benzodiazepine receptor agonists) but not clonazepam (a molecule with low affinity for the peripheral-type benzodiazepine receptor) decreased the percentage of tumor cells in G0-G1 phases and increased that of cells in S-G2-M phases. The effects of those agonists were prevented by PK11195 (a peripheral-type benzodiazepine receptor antagonist) that did not produce effects by itself. Altogether, these data suggest that the presence of peripheral-type benzodiazepine receptor within the nucleus of Ehrlich tumor cells is associated with tumor malignity and proliferation capacity.

Effects of Pfaffia paniculata (Brazilian ginseng) extract on macrophage activity

The roots of Pfaffia paniculata (Brazilian ginseng) have been indicated for the treatment of several diseases and as an analgesic and antiinflamatory drug. Treatment of mice with 200 mg/kg of the powdered root of P. paniculata reduced the Ehrlich ascitic volume [Matsuzaki, P., Akisue, G., Salgado Oloris, S.C., Gorniak, S.L., Zaidan Dagli, M.L., 2003. Effect of Pffafia paniculata (Brazilian ginseng) on the Ehrlich tumor on its ascitic form. Life Sciences, Dec 19; 74 (5), 573-579.]. One of the putative means to control the Ehrlich tumor growth is by increasing macrophage activity [Kleeb, S.R., Xavier, J.G., Frussa-Filho, R., Dagli, M.L.Z., 1997. Effect of haloperidol on the development of the solid Ehrlich tumor in mice. Life Sciences, 60 (4/5), 69-742.]. The aim of this study was to investigate experimentally the effects of the methanolic extract of P. paniculata roots on macrophage activity. Male mice received, by gavage, once a day, different doses (100, 250, or 500 mg/kg) of the methanolic extract of P. paniculata or filtered water, as control, for 10 days. Macrophage activity was evaluated through the phagocytosis index (PI), spreading index (SI), production of peroxide oxigen and nitric oxide. The peritoneal cells were activated with ip inoculation of Ehrlich ascitic cells, 24 h before the macrophage harvesting. The methanolic extract raised significantly the SI of mice from group of 500 mg/kg in comparison with the control group and group of 100 mg/kg. This raise of SI possibly induced the higher phagocytic activity observed in the experimental situation. Increased macrophage activity may be one of the effects contributing to inhibition of the Ehrlich ascitic tumor growth in mice.

Glomus tumour in the digit of a dog

The gross and microscopical features of a glomus tumour in the digit of a 9-year-old dog are described. The tumour consisted of a red nodule near the nail of the third digit of the right forelimb and appeared painful. The tumour cells, which had round to oval hyperchromatic nuclei and scant cytoplasm, were arranged in sheets around blood vessels, or in nests or duct-like structures. This pattern has not been described previously in canine glomus tumours. Mitotic figures were seen only occasionally. Tumour cells were strongly immunolabelled for vimentin and some expressed smooth-muscle actin and desmin. They were negative for cytokeratins, neuron-specific enolase and CD34. Silver impregnation (reticulin method) stained the reticulum around blood vessels, nests of tumour cells and duct-like structures, and a delicate reticulum was seen around each tumour cell. The morphological, immunohistochemical and histochemical patterns helped in the diagnosis of this glomus tumour.