The role of platelet and plasma markers of antioxidant status and oxidative stress in thrombocytopenia among patients with vivax malaria

Malaria remains an important health problem in tropical countries like Brazil. Thrombocytopenia is the most common hematological disturbance seen in malarial infection. Oxidative stress (OS) has been implicated as a possible mediator of thrombocytopenia in patients with malaria. This study aimed to investigate the role of OS in the thrombocytopenia of Plasmodium vivax malaria through the measurement of oxidant and antioxidant biochemical markers in plasma and in isolated platelets. Eighty-six patients with P. vivax malaria were enrolled. Blood samples were analyzed for total antioxidant and oxidant status, albumin, total protein, uric acid, zinc, magnesium, bilirubin, total thiols, glutathione peroxidase (GPx), malondialdehyde (MDA), antibodies against mildly oxidized low-density lipoproteins (LDL-/nLDL ratio) and nitrite/nitrate levels in blood plasma and GPx and MDA in isolated platelets. Plasma MDA levels were higher in thrombocytopenic (TCP) (median 3.47; range 1.55-12.90 µmol/L) compared with the non-thrombocytopenic (NTCP) patients (median 2.57; range 1.95-8.60 µmol/L). Moreover, the LDL-/nLDL autoantibody ratio was lower in TCP (median 3.0; range 1.5-14.8) than in NTCP patients (median 4.0; range 1.9-35.5). Finally, GPx and MDA were higher in the platelets of TPC patients. These results suggest that oxidative damage of platelets might be important in the pathogenesis of thrombocytopenia found in P. vivax malaria as indicated by alterations of GPx and MDA.

Trypanosoma cruzi: a stage-specific calpain-like protein is induced after various kinds of stress

Calpains are calcium-dependent cysteine proteinases found in all living organisms and are involved in diverse cellular processes. Calpain-like proteins have been reported after in silico analysis of the Tritryps genome and are believed to play important roles in cell functions of trypanosomatids. We describe the characterization of a member of this family, which is differentially expressed during the life-cycle of Trypanosoma cruzi.

Oxidative stress response to menadione and cumene hydroperoxide in the opportunistic fungal pathogen Candida glabrata

Candida glabrata is an opportunistic fungal pathogen that can cause severe invasive infections and can evade phagocytic cell clearance. We are interested in understanding the virulence of this fungal pathogen, in particular its oxidative stress response. Here we investigated C. glabrata, Saccharomyces cerevisiae and Candida albicans responses to two different oxidants: menadione and cumene hydroperoxide (CHP). In log-phase, in the presence of menadione, C. glabrata requires Cta1p (catalase), while in a stationary phase (SP), Cta1p is dispensable. In addition, C. glabrata is less resistant to menadione than C. albicans in SP. The S. cerevisiae laboratory reference strain is less resistant to menadione than C. glabrata and C. albicans; however S. cerevisiaeclinical isolates (CIs) are more resistant than the lab reference strain. Furthermore, S. cerevisiae CIs showed an increased catalase activity. Interestingly, in SP C. glabrata and S. cerevisiae are more resistant to CHP than C. albicans and Cta1p plays no apparent role in detoxifying this oxidant.

Characterization of TcSTI-1, a homologue of stress-induced protein-1, in Trypanosoma cruzi

The life cycle of the protozoan Trypanosoma cruzi exposes it to several environmental stresses in its invertebrate and vertebrate hosts. Stress conditions are involved in parasite differentiation, but little is known about the stress response proteins involved. We report here the first characterization of stress-induced protein-1 (STI-1) in T. cruzi (TcSTI-1). This co-chaperone is produced in response to stress and mediates the formation of a complex between the stress proteins HSP70 and HSP90 in other organisms. Despite the similarity of TcSTI-1 to STI-1 proteins in other organisms, its expression profile in response to various stress conditions, such as heat shock, acidic pH or nutrient starvation, is quite different. Neither polysomal mRNA nor protein levels changed in exponentially growing epimastigotes cultured under any of the stress conditions studied. Increased levels of TcSTI-1 were observed in epimastigotes subjected to nutritional stress in the late growth phase. Co-immunoprecipitation assays revealed an association between TcSTI-1 and TcHSP70 in T. cruzi epimastigotes. Immunolocalization demonstrated that TcSTI-1 was distributed throughout the cytoplasm and there was some colocalization of TcSTI-1 and TcHSP70 around the nucleus. Thus, TcSTI-1 associates with TcHSP70 and TcSTI-1 expression is induced when the parasites are subjected to stress conditions during specific growth phase.

The level of ascorbate peroxidase is enhanced in benznidazole-resistant populations of Trypanosoma cruzi and its expression is modulated by stress generated by hydrogen peroxide

Ascorbate peroxidases (APX) are class I heme-containing enzymes that convert hydrogen peroxide into water molecules. The gene encoding APX has been characterized in 11 strains of Trypanosoma cruzi that are sensitive or resistant to benznidazole (BZ). Bioinformatic analysis revealed the presence of two complete copies of the T. cruzi APX (TcAPX) gene in the genome of the parasite, while karyotype analysis showed that the gene was present in the 2.000-kb chromosome of all of the strains analyzed. The sequence of TcAPX exhibited greater levels of similarity to those of orthologous enzymes from Leishmania spp than to APXs from the higher plant Arabidopsis thaliana. Northern blot and real-time reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed no significant differences in TcAPX mRNA levels between the T. cruzi strains analyzed. On the other hand, Western blots showed that the expression levels of TcAPX protein were, respectively, two and three-fold higher in T. cruzi populations with in vitro induced (17 LER) and in vivo selected (BZR) resistance to BZ, in comparison with their corresponding susceptible counterparts. Moreover, the two BZ-resistant populations exhibited higher tolerances to exogenous hydrogen peroxide than their susceptible counterparts and showed TcAPX levels that increased in a dose-dependent manner following exposure to 100 and 200 µM hydrogen peroxide.

Superoxide dismutases and glutaredoxins have a distinct role in the response of Candida albicans to oxidative stress generated by the chemical compounds menadione and diamide

To cope with oxidative stress, Candida albicans possesses several enzymes involved in a number of biological processes, including superoxide dismutases (Sods) and glutaredoxins (Grxs). The resistance of C. albicans to reactive oxygen species is thought to act as a virulence factor. Genes such as SOD1 and GRX2, which encode for a Sod and Grx, respectively, in C. albicans are widely recognised to be important for pathogenesis. We generated a double mutant, Δgrx2/sod1, for both genes. This strain is very defective in hyphae formation and is susceptible to killing by neutrophils. When exposed to two compounds that generate reactive oxygen species, the double null mutant was susceptible to menadione and resistant to diamide. The reintegration of the SOD1 gene in the null mutant led to recovery in resistance to menadione, whereas reintegration of the GRX2 gene made the null mutant sensitive to diamide. Despite having two different roles in the responses to oxidative stress generated by chemical compounds, GRX2 and SOD1 are important for C. albicans pathogenesis because the double mutant Δgrx2/sod1 was very susceptible to neutrophil killing and was defective in hyphae formation in addition to having a lower virulence in an animal model of systemic infection.

Oxidative stress enhances the expression of sulfur assimilation genes: preliminary insights on the Enterococcus faecalis iron-sulfur cluster machinery regulation

The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.

Medidas de prevenção e controle de infecções urinarias hospitalares em hospitais da cidade de São Paulo

Trata-se de parte de estudo onde avalia-se o conhecimento e a prática de enfermeiros e ocupacionais de enfermagem em relação a medidas de prevenção e controle de infecções hospitalares em vinte e nove hospitais gerais, da cidade de São Paulo. Objetiva, além de avaliar o conhecimento e a prática acerca das medidas de prevenção e controle das infecções, investigar se existem diferenças entre os níveis de conhecimento e de atuação prática dos enfermeiros e ocupacionais de enfermagem, quando lotados em diferentes grupos de hospitais: hospitais públicos com serviço de prevenção e controle de infecções hospitalares; hospitais públicos sem serviço de prevenção e controle de infecções hospitalares; hospitais privados com serviço e privados sem o referido serviço. Constata-se que existem lacunas no que se refere ao conhecimento e a prática acerca das medidas de prevenção e controle das infecções estudadas e que embora se detectem diferenças significativas para o conhecimento e a prática dos profissionais e ocupacionais de enfermagem, quando lotados em diferentes grupos de hospitais, a análise de perguntas isoladas nem sempre distingue, com significância, os mesmos grupos.

Prevenção de úlceras nos membros inferiores em pacientes com diabetes mellitus

Este artigo de atualização discute os riscos para o desenvolvimento de úlceras em membros inferiores a que os pacientes com diabetes mellitus estão expostos, ao longo da vida. A patogênese das úlceras diabéticas é enfocada com o objetivo de dar subsídios ao enfermeiro para avaliar a capacidade de manutenção da integridade cutânea e adequar as medidas preventivas necessárias.

Fatores de risco para úlcera de pressão: subsídios para a prevenção

Uma das complicações mais severas para a pessoa com lesão medular é a úlcera de pressão. Sendo assim a prevenção destas feridas e a identificação de fatores de risco são necessidades prementes para o enfermeiro. Trata-se de um estudo decorrente de uma pesquisa mais abrangente, que abordou a assistência de enfermagem ao lesado medular em reabilitação buscando identificar os fatores de risco para úlcera de pressão utilizando os registros das enfermeiras nos históricosde enfermagem e a Taxonomia I da NANDA e analisar as intervenções de enfermagem preconizados face ao diagnóstico potencial para prejuízo na integridade da pele. Os fatores de risco identificados referem-se às alterações decorrentes da lesão neurológica, história prévia de ferida e lesão inicial. As intervenções de enfermagem preconizadas totalizaram. 16, com caráter de orientação ao paciente e à família voltadas para higiene corporal, mudança de decúbito, posicionamento no leito e em cadeira de rodas, denotando pertinência ao diagnóstico elaborado.

Paramentação cirúrgica: avaliação de sua adequação para a prevenção de riscos biológicos em cirurgias. Parte I: a utilização durante as cirurgias

O estudo elaborou critérios para uso adequado da paramentação cirúrgica e avaliou, por observação sistematizada, o desempenho da equipe cirúrgica durante a cirurgia. O procedimento adotado foi válido, permitindo reconhecer aspectos positivos e problemáticos. A exceção do óculos protetor, todos os outros componentes da paramentação foram utilizados. A questão se situou na forma de utilização, onde gorros e máscaras foram mais problemáticos entre anestesistas e circulantes; avental e luvas entre cirurgiões e, principalmente, instrumentadores.

Paramentação cirúrgica: avaliação de sua adequação para a prevenção de riscos biológicos em cirurgias - parte II: os componentes da paramentação

O estudo elaborou critérios de avaliação dos componentes da paramentação cirúrgica de hospitais do município de São Paulo. A maior dificuldade nessa elaboração deveu-se à inexistência de normas e consenso sobre a porosidade dos tecidos como barreira microbiológica e de contato com sangue e outros fluidos. Contudo, foi possível reconhecer aspectos positivos e problemáticos. Observou-se que existe semelhanças dos componentes entre os hospitais, no que se refere a modelo e tipo de tecido. As luvas foram os componentes com maior índice de adequação e os propés, os de maior índice de inadequação. O aspecto mais problemático referiu-se aos controles de aquisição e de reprocessamento dos componentes re-utilizáveis.

Enfermeiro hospitalar e o stress

Relata a comparação do nível de stress no desempenho das atividades do enfermeiro de instituição hospitalar em unidades consideradas abertas e fechadas. Constatou-se que os enfermeiros que atuam em unidades abertas obtiveram maior nível de stress do que aqueles que trabalham em unidades fechadas e praticamente a atuação relacionada à administração de pessoal foi considerada estressante para a totalidade de enfermeiros. E necessária a educação do enfermeiro para minimizar esses fatores estressantes.