Effect of Bothrops alternatus snake venom on macrophage phagocytosis and superoxide production: participation of protein kinase C

Envenomations caused by different species of Bothrops snakes result in severe local tissue damage, hemorrhage, pain, myonecrosis, and inflammation with a significant leukocyte accumulation at the bite site. However, the activation state of leukocytes is still unclear. According to clinical cases and experimental work, the local effects observed in envenenomation by Bothrops alternatus are mainly the appearance of edema, hemorrhage, and necrosis. In this study we investigated the ability of Bothrops alternatus crude venom to induce macrophage activation. At 6 to 100 »g/mL, BaV is not toxic to thioglycollate-elicited macrophages; at 3 and 6 »g/mL, it did not interfere in macrophage adhesion or detachment. Moreover, at concentrations of 1.5, 3, and 6 »g/mL the venom induced an increase in phagocytosis via complement receptor one hour after incubation. Pharmacological treatment of thioglycollate-elicited macrophages with staurosporine, a protein kinase (PKC) inhibitor, abolished phagocytosis, suggesting that PKC may be involved in the increase of serum-opsonized zymosan phagocytosis induced by BaV. Moreover, BaV also induced the production of anion superoxide (O2-) by thioglycollate-elicited macrophages. This BaV stimulated superoxide production was abolished after treating the cells with staurosporine, indicating that PKC is an important signaling pathway for the production of this radical. Based on these results, we suggest that phagocytosis and reactive oxygen species are involved in the pathogenesis of local tissue damage characteristic of Bothrops spp. envenomations.

Human parvovirus B19 infection in HIV-positive patients

Parvovirus B19 infects predominantly erythroid cells, leading to transient inhibition of erythropoiesis. Immunocompromised patients may be unable to produce neutralizing antibodies and may develop severe chronic anemia. Epidemiological studies done on Niterói population showed that B19 infection occurs periodically in late spring and summer. We report a study from 55 HIV infected patients attending an infectious diseases outpatient clinic in this city during a 5-month period in which B19 circulation was well documented. All patients were under anti-retroviral therapy. No anti-B19 IgM was found, but a high prevalence of IgG anti-B19 (91%) was observed. In six patients, B19 DNA was found by dot-blot hybridization techniques, but this was not confirmed by PCR. None of these 6 patients manifested anemia and only one had CD4 cell count below 200 x 10(7)/L. We conclude that persistent infection causing anemia is an infrequent finding in our HIV positive patients under drug therapy.

O parvovírus B19 infecta predominantemente células eritróides, causando inibição transitória da eritropoiese. Pacientes imunocomprometidos podem ser incapazes de produzir anticorpos neutralizantes, evoluindo com grave anemia crônica. Estudos epidemiológicos da população de Niterói mostraram que a infecção ocorre periodicamente no final da primavera e no verão. Descrevem-se 55 pacientes infectados pelo HIV atendidos num ambulatório de doenças infecciosas nesta cidade num período de cinco meses, no qual a circulação do parvovírus B19 foi documentada. Todos os pacientes estavam sob terapia anti-retroviral. Não se encontrou IgM anti-B19, mas notou-se uma prevalência alta de IgG anti-B19 (91%). Em seis pacientes verificou-se a presença de DNA do B19 por hibridização em dot-blot, o que não se confirmou por PCR. Nenhum destes seis pacientes tinha anemia, e apenas um tinha células CD4 abaixo de 200 x 107/L. Conclui-se que infecção persistente causando anemia é um achado infreqüente em nossos pacientes HIV positivos sob terapia medicamentosa.

Associacao da rifampicina a anfotericina B no tratamento da paracoccidioidomicose. Resultados em tres pacientes tratados. / Combination of rifampicin with amphotericin B in the treatment of paracoccidioidomycosis.Results in 3 treated patients

Trabalhos experimentais demonstraram que a anfotericina B, desorganizando funcionalmente a membrana celular fungica, permite a penetracao da rifampicina no citoplasma e sua consequente acao contra Histoplasma capsulatum, Blastomyces dermatitidis e Candida albicans. Com metade das doses habituais de anfotericina B associada a rifampicina conseguem-se melhores resultados do que com a anfotericina B isoladamente em doses plenas. Os Autores discutem as possiveis aplicacoes desta associacao no tratamento da paracoccidioidomicose e apresentam 3 casos desta micose em que a inatividade clinica e micologica so foi obtida apos o emprego combinado destas drogas