Actin-interacting and flagellar proteins in Leishmania spp: bioinformatics predictions to functional assignments in phagosome formation

Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented.

Margem de segurança do meloxicam em cäes: efeitos deletérios nas células sangüíneas e trato gastrintestinal / Margin of safety of meloxicam in dogs: deleterious effects on blood cells and gastrointestinal tract

Este trabalho investigou a margem de segurança do inibidor COX-2, meloxicam, em cäes, enfocando seus efeitos deletérios nas células sangüíneas e no trato gastrintestinal. Para tanto, após uma avaliaçäo clínico-laboratorial, os cäes foram distribuídos nos seguintes grupos: I (placebo; n= 3), II (piroxicam; 1,0mg kg(1); n= 5), III (meloxicam; 0,2mg kg(1); n= 5), IV (meloxicam; 1,0mg kg(1); n= 5) e V (meloxicam; 2,0mg kg(1); n= 5). Os fármacos foram usados, por via oral, por 16 dias. No 17§ dia, repetiu-se o hemograma completo e, entäo, procedeu-se a eutanásia seguida pela necrópsia. No grupo I, näo houve alteraçöes dignas de nota. No grupo II, todos os cäes apresentaram episódios moderados de vômito e diarréia. O perfil celular sangüíneo näo foi significativamente modificado. Em dois cäes, houve reduçäo no hematócrito e na hemoglobina. Na necropsia, observaram-se focos hemorrágicos e lesöes gastriduodenais moderadas. A análise microscópica revelou a presença de gastrite e enterite ulcerativa. No grupo III, quatro cäes (80 por cento) apresentaram vômito e diarréia, sem alteraçäo no perfil celular sangüíneo. Na análise macroscópica, observaram-se lesöes brandas na mucosa gástrica e focos hemorrágicos no duodeno em quatro cäes. Na histopatologia, observaram-se lesöes sugestivas de discreta gastroenterite. No grupo IV, os cinco cäes tiveram vômito e diarréia sanguinolenta. Quatro deles (80 por cento) apresentaram anemia (p< ou = 0,05). Quatro e cinco cäes apresentaram reduçäo no hematócrito e hemoglobina, respectivamente. Ocorreram, ainda, leucocitose, neutrofilia e linfopenia significantes (p < ou = 0,05, em 60 por cento dos cäes. Na necrópsia, evidenciaram-se hiperemia, hemorragia e úlceras gástricas severas em 100 por cento dos animais. Verificou-se na microscopia um quadro de gastroenterite ulcerativa nos cinco cäes. No grupo V, todos os cäes apresentaram sérios episódios de vômito, diarréia e melena. Os quatro (80 por cento) cäes que suportaram o tratamento apresentaram anemia e leucocitose com neutrofilia e linfopenia significativas (p< ou = 0,05). Houve, ainda, uma reduçäo no hematócrito e hemoglobina desses cäes. Na necropsia, foram visualizadas hemorragias e graves ulceraçöes gastroduodenais. A histopatologia, evidenciou-se severa gastroenterite....

Immunization with PIII, a fraction of Schistosoma mansoni soluble adult worm antigenic preparation, affects nitric oxide production by murine spleen cells

Nitric oxide (NO) is an important effector molecule involved in immune regulation and defense. NO produced by cytokine-activated macrophages was reported to be cytotoxic against the helminth Schistosoma mansoni. Identification and characterization of S. mansoni antigens that can provide protective immunity is crucial for understanding the complex immunoregulatory events that modulate the immune response in schistosomiasis. It is, then, essential to have available defined, purified parasite antigens. Previous work by our laboratory identified a fraction of S. mansoni soluble adult worm antigenic preparation (SWAP), named PIII, able to elicit significant in vitro cell proliferation and at the same time lower in vitro and in vivo granuloma formation when compared either to SEA (soluble egg antigen) or to SWAP. In the present work we report the effect to different in vivo trials with mice on their spleen cells ability to produce NO. We demostrate that PIII-immunization is able to significantly increase NO production by spleen cells in vitro stimulation with LPS. These data suggest a possible role for NO on the protective immunity induced by PIII.