Increased susceptibility to Strongyloides venezuelensis in mice due to Mycobacterium bovis co-infection which modulates production of Th2 cytokines.

An estimated quarter of the world's population possesses an infection caused by gastrointestinal nematodes, which induce a Th2 type immune response. Concomitant infection of nematodes with Mycobacterium tuberculosis, which induces a predominantly Th1 type response, is very frequent in tropical and subtropical regions. This study examined immune responses of BALB/c mice infected with Strongyloides venezuelensis and then co-infected with Mycobacterium bovis. The number of worms in the intestine, eggs in feces, cytokine production in lungs and intestine and the expression of CD80, CD86, CTLA-4 and CD28 cell markers on pulmonary cells were analysed. Our results indicate that co-infected mice had an increased parasite burden, which correlates with elevated IFN-gamma and IL-10 cytokine production and decreased IL-4 and IL-13. Moreover, decreased expression of CD80 and increased expression of CTLA-4 were observed in co-infected mice. Our data point out that susceptibility to Strongyloides venezuelensis infection is increased by Mycobacterium bovis co-infection, resulting in higher parasite survival.

Exame direto no diagnóstico de Paracoccidiodes brasiliensis realizado nos laboratórios regionais do Instituto Adofo Lutz, São Paulo, Brasil / Use of direct microscopic examination for Paracoccidioides brasiliensis diagnosis at Instituto Adolfo Lutz (IAL) Regional Laboratories Network, State of São Paulo, Brazil

Paracoccidioidomicose (PCM) é uma doença sistêmica causada pelo fungo dimórfico Paracoccidioides brasiliensis. Apresenta-se como infecção pulmonar primária assintomática, aguda, sub-aguda ou crônica. Para ratificar a importância do exame direto, de baixo custo e complexidade, no diagnóstico da PCM, foi realizado um levantamento de amostras clínicas nos Laboratórios Regionais do IAL (LR-IAL) e Laboratório I Araçatuba– DIR VI, no período de janeiro de 1996 a dezembro de 2002. Foram analisadas 3807 amostras de origem pulmonar e 25 amostras extrapulmonares, preparadas de acordo com suas peculiaridades. Detectou-se significativa quantidade de solicitações de exames com informações incompletas quanto aos dados do paciente. Foi demonstrada positividade em 4% das amostras pulmonares (predominando no adulto do sexo masculino) assim como em amostras extrapulmonares (88%). A diferença na demanda natural das solicitações para este diagnóstico, entre os Regionais, pode estar relacionada com endemicidade da região, busca e/ou suspeita da doença e encaminhamento das amostras para os Laboratórios de Referência da Rede Pública. Após 98 anos da descrição pioneira por Adolfo Lutz, a doença ainda é foco de preocupação para a Saúde Pública.

Sorption of phenanthrene by reference smectites.

Fate and behavior of nonionic hydrophobic organic compounds (HOCs) in the environment is mainly controlled by their interactions with various components of soils and sediments. Due to their large surface area and abundance in many soils, smectites may greatly influence the fate and transport of HOCs in the environment. We used phenanthrene as a probe to explore the potential of reference smectites to sorb HOCs from aqueous solution. Batch experiments were used to construct phenanthrene sorption isotherms, and possible sorption mechanisms were inferred from the shape of the isotherms. Our results demonstrate that smectites can retain large amounts of phenanthrene from water. Phenanthrene sorption capacities of the reference smectites investigated in this study were comparable to those of soil clays containing a considerable amount of organic matter. Hectorite exhibited the highest sorption affinity and capacity followed by Panther Creek montmorillonite. The lack of correlation between Freundlich sorption constants (K'f) and indices of charge or hydrophobicity suggests that sorption of phenanthrene by smectites is primarily a physical phenomenon. Capillary condensation into a network of nanoor micropores created by quasicrystals is likely to be a dominant mechanism of phenanthrene retention by smectites.

Incidência de Dermatofitoses e candidoses em pacientes HIV soropositivos / Incidence of dermatophytosis and candidosis in HIV - positive patients

Freqüentemente pacientes HIV soropositivos têm micoses superficiais em qualquer estágio da AIDS. Objetivos: traçar um perfil da população HIV soropositiva quanto à frqüência dessa dermatose, faixa etária acometida, características clínicas e agentes etiológicos. Foram divididos pacientes com quadro clínico de micoses superficiais, sendo colhidas amostras de pele/unhas a fim de serem submetidas à pesquisa laboratorial mediante exame micológico direto após clareamento com potassa a 20%. A seguir, procedeu-se ao cultivo em ágar-Sabouraud e microcultivo em ágar-fubá (leveduras) ou ágar-batata (dermatófitos). Dos 32 pacientes avaliados, com micoses superficiais, a pesquisa laboratorial resultou positiva em 58% dos casos. Os fundos mais encontrados foram a Candida sp (32%) e o Tricophyton mentagrophytes (32%). A faixa etária mais acometida foi a de 20 a 35 anos. A pequena amostra dos autores concorda com a literatura ao observar a Candida como o agente fúngico mais freqüente em pacientes HIV soropositivos. Lesões ungueais foram as mais observadas. O dermatófito mais comum foi o Trichophyton mentagrophytes, enquanto a literatura aponta o Tricophyton rubrum. Devida às conseqüencias fisiopatológicas , elevando a morbidade em pacientes com AIDS, ressalta-se a importância de micoses superficiais nesses pacientes

CD2 and CD3 associate independently with CD5 and differentially regulate signaling through CD5 in Jurkat T cells.

In T lymphocytes, the CD2 and CD5 glycoproteins are believed to be involved in the regulation of signals elicited by the TCR/CD3 complex. Here we show that CD2 and CD3 independently associate with CD5 in human PBMC and Jurkat cells. CD5 coprecipitates with CD2 in CD3-deficient cells and, conversely, coprecipitates with CD3 in cells devoid of CD2. In unstimulated CD2+ CD3+ Jurkat cells, CD5 associates equivalently with CD2 and CD3 and is as efficiently phosphorylated in CD2 as in CD3 immune complexes. However, upon activation the involvement of CD5 is the opposite in the CD2 and CD3 pathways. CD5 becomes rapidly tyrosine phosphorylated after CD3 stimulation, but is dephosphorylated upon CD2 cross-linking. These opposing effects correlate with the decrease in the activity of the SH2 domain-containing protein phosphatase 1 (SHP-1) following CD3 activation vs an enhanced activity of the phosphatase after CD2 triggering. The failure of CD5 to become phosphorylated on tyrosine residues in the CD2 pathway has no parallel with the lack of use of zeta-chains in CD2 signaling; contrasting with comparable levels of association of CD2 or CD3 with CD5, zeta associates with CD2 only residually and is nevertheless slightly phosphorylated after CD2 stimulation. The modulation of CD5 phosphorylation may thus represent a level of regulation controlled by CD2 in signal transduction mechanisms in human T lymphocytes.

Calreticulin is expressed on the cell surface of activated human peripheral blood T lymphocytes in association with major histocompatibility complex class I molecules.

Calreticulin is an endoplasmic reticulum resident molecule known to be involved in the folding and assembly of major histocompatibility complex (MHC) class I molecules. In the present study, expression of calreticulin was analyzed in human peripheral blood T lymphocytes. Pulse-chase experiments in [35S]methionine-labeled T cell blasts showed that calreticulin was associated with several proteins in the endoplasmic reticulum and suggested that it was expressed at the cell surface. Indeed, the 60-kDa calreticulin was labeled by cell surface biotinylation and precipitated from the surface of activated T cells together with a protein with an apparent molecular mass of 46 kDa. Cell surface expression of calreticulin by activated T lymphocytes was further confirmed by immunofluorescence and flow cytometry, studies that showed that both CD8+ and CD4+ T cells expressed calreticulin in the plasma membrane. Low amounts of cell surface calreticulin were detected in resting T lymphocytes. By sequential immunoprecipitation using the conformation independent monoclonal antibody HC-10, we provided evidence that the cell surface 46-kDa protein co-precipitated with calreticulin is unfolded MHC I. These results show for the first time that after T cell activation, significant amounts of calreticulin are expressed on the T cell surface, where they are found in physical association with a pool of beta2-free MHC class I molecules.

Perfil epidemiológico das patologias oculares externas / Epidemiological profile of the external diseases of the eye

As doenças oculares externas agudas constituem parte significativa do atendimento de qualquer serviço oftalmológico. Através de um estudo prospectivo, os autores fizeram um levantamento epidemiológico das patologias oculares externas atendidas no serviço, ressaltando os resultados de cultura e de sensibilidade antibiótica.

Association of the transmembrane 4 superfamily molecule CD53 with a tyrosine phosphatase activity.

Cell surface proteins of the transmembrane 4 superfamily (TM4SF) are a newly characterized family of proteins which are presumed to span the plasma membrane four times. The function of this family of molecules is poorly understood, but based on monoclonal antibody studies there is some evidence that they may be involved in transmembrane signal transduction and regulation of cell proliferation, differentiation, or both, in a number of different cell types. CD53 is a member of this family that is expressed on leukocytes, and transduces activation signals through unknown mechanisms that may involve phosphorylation events. However, CD53 has never been shown to associate directly with kinases. Here, we show by immunoprecipitation from cell lysates of lymph nodes and a thymoma cell line, that immune complexes of rat CD53 contain tyrosine phosphatase activity. The CD53-associated phosphatase was able to dephosphorylate in vitro the phosphorylated tyrosine kinase Lck, as well as a synthetic substrate, and its activity was abrogated by a tyrosine phosphatase inhibitor. Although its identity has not been established, it is clear from depletion experiments that it is not CD45. CD63, a second member of the TM4SF, also co-precipitates a phosphatase activity from rat basophilic leukemia cells. These results demonstrate that the TM4SF members associate with tyrosine phosphatases. It seems possible that such associated phosphatases may contribute to the signal transduction capacity of TM4SF molecules.

The association of the protein tyrosine kinases p56lck and p60fyn with the glycosyl phosphatidylinositol-anchored proteins Thy-1 and CD48 in rat thymocytes is dependent on the state of cellular activation.

Cell surface glycoproteins anchored to the plasma membrane via glycosylphosphatidylinositol (GPI) structures, and hence having no cytoplasmic domains, can nevertheless transmit activation signals in lymphocytes. By immunoprecipitation from detergent lysates and in vitro immune complex kinase reactions the GPI-anchored molecules Thy-1 and CD48 are shown to be associated with multimolecular complexes of phosphoproteins including the protein tyrosine kinases p56lck and p60fyn in both rat and mouse thymocytes. Moreover, the kinase activity associated with Thy-1 on rat thymocytes is shown to be dependent on the activation state of the cells, with stimulation by the lectin, concanavalin A, producing a marked decrease in Thy-1-associated kinase activity. In such activated cells, there is an increased association of kinase activity with CD48, but this may be explained in terms of increased surface expression of CD48 and of increased total kinase activity. Additional phosphoproteins of 85, 36 and 32 kDa were consistently seen as components of the complexes.

Physical association of the cytoplasmic domain of CD2 with the tyrosine kinases p56lck and p59fyn.

In T lymphocytes, CD2 forms part of a loosely associated membrane complex which includes the T cell receptor (TcR) for antigen, the CD3 subunits, CD4 or CD8, CD5 and the protein tyrosine kinases p56lck and p59fyn. The interaction of CD2 with tyrosine kinases in this complex provides a possible mechanism for transmembrane signal transduction by CD2. We have investigated whether the interaction of CD2 with the kinases is dependent on other known members of the complex, or whether an independent association can be observed. Using in vitro kinase assays with immune complexes precipitated from cell lysates, we demonstrate that CD2 can associate with p56lck and p59fyn in a rat thymoma line that does not express CD4 or CD8, and in a TcR-negative Jurkat cell line. In TcR-positive Jurkat cells that express rat CD2, interaction of CD2 with p56lck and p59fyn was clearly seen, but it was absent in cells where the cytoplasmic tail of CD2 is truncated, indicating that the interactions are mediated by the cytoplasmic region of CD2. Furthermore, using cells expressing CD2 molecules with partial truncations in the cytoplasmic domain, we show that the association of CD2 with p56lck is progressively lost as the cytoplasmic domain is shortened, and that the capacity of the mutants to associate with p56lck correlates with their capacity to transduce transmembrane signals.