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.

Effect of mouse antisera targeting the Phlebotomus papatasi midgut chitinase PpChit1 on sandfly physiology and fitness

In sandflies, the absence of the peritrophic matrix (PM) affects the rate of blood digestion. Also, the kinetics of PM secretion varies according to species. We previously characterised PpChit1, a midgut-specific chitinase secreted in Phlebotomus papatasi (PPIS) that is involved in the maturation of the PM and showed that antibodies against PpChit1 reduce the chitinolytic activity in the midgut of several sandfly species. Here, sandflies were fed on red blood cells reconstituted with naïve or anti-PpChit1 sera and assessed for fitness parameters that included blood digestion, oviposition onset, number of eggs laid, egg bouts, average number of eggs per bout and survival. In PPIS, anti-PpChit1 led to a one-day delay in the onset of egg laying, with flies surviving three days longer compared to the control group. Anti-PpChit1 also had a negative effect on overall ability of flies to lay eggs, as several gravid females from all three species were unable to lay any eggs despite having lived longer than control flies. Whereas the longer survival might be associated with improved haeme scavenging ability by the PM, the inability of females to lay eggs is possibly linked to changes in PM permeability affecting nutrient absorption.

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.

Stress no trabalho do enfermeiro

Este estudo avaliou o stress associado ao trabalho do enfermeiro no trabalho com o portador de transtorno mental inserido no contexto do hospital psiquiátrico. Trata-se de pesquisa quantitativa, analítica, realizada em sete hospitais psiquiátricos da cidade de Fortaleza, Ceará. Utilizou-se os seguintes instrumentos: dados sociodemográficos para descrição da amostra e um inventário para identificar os sintomas de stress no enfermeiro. A população total abrangeu 48 participantes e a amostra 42, a maioria do sexo feminino, o que corresponde a 92,9% do total. Os resultados mostram que em 62% da amostra não apresentaram stress, 30,9% encontravam-se na fase de Resistência e apenas 7,1% na fase de Exaustão. Não houve associação estatisticamente significativa entre a variável tempo de trabalho com o portador de transtorno mental e sintomas de stress. Portanto, o presente estudo não evidenciou a ocorrência do stress nesses profissionais enfermeiros.

Stress e coping no período perioperatório de câncer de mama

Este trabalho é uma revisão bibliográfica, que objetiva refletir sobre stress e coping no perioperatório de câncer de mama, realizada em bases de dados on-line nacionais, abrangendo trabalhos publicados de 1996 a 2006. Foram encontrados 63 artigos, sendo selecionados 17, que foram lidos, analisados e agrupados em categorias temáticas: 1) O câncer de mama como estressor e o impacto do diagnóstico; 2) Stress e o tratamento do câncer de mama; 3) Coping e o câncer de mama, e 4) O enfermeiro como colaborador do processo de enfrentamento. Esse trabalho permitiu identificar que é vasta a literatura nacional sobre câncer de mama, mas poucos são os trabalhos que enfatizam stress e câncer de mama como processo vivenciado pela paciente. Por isso, pode dar direção a pesquisas futuras acerca dos estressores vivenciados pela mulher com câncer de mama no Brasil, e quais as estratégias de coping que ela utiliza para enfrentá-los.

Escala Bianchi de Stress

A Escala Bianchi de Stress foi construída e validada para avaliar o nível de stress do enfermeiro hospitalar no desempenho básico de suas atividades. É auto-aplicável, composta por 51 itens, divididos em seis domínios, que recebem uma pontuação com variação de 1 a 7. Os domínios são compostos por atividades envolvendo a assistência e o gerenciamento do cuidado. Com a sua utilização, pode-se verificar o domínio mais estressante para o grupo de enfermeiros ou para cada indivíduo e também avaliar as atividades mais estressantes naquela instituição. É um instrumento que auxilia na tomada de decisão para a implantação de estratégias de enfrentamento do stress do enfermeiro hospitalar.

Imagens e representações da enfermagem acerca do stress e sua influência na atividade laboral

Os objetivos deste estudo foram: identificar as representações acerca dos fatores desencadeadores do estresse, atribuídos pelos profissionais de enfermagem, na atividade laboral; e discutir a influência destes na sua atividade laboral. Optou-se por um estudo descritivo com abordagem qualitativa, para o qual foram utilizadas as premissas das Representações Sociais, tendo os estudos realizados como referencial de análise. Para coleta utilizou-se como instrumento entrevista semiestruturada e individual. A análise foi através da técnica de análise de conteúdo, a fim de buscar elementos para a compreensão das imagens como representações dos profissionais de enfermagem, o significado dos fatores estressantes, e sua influência na atividade laboral. A população estudada vive e convive com a falta de condições de trabalho, escassez de recursos materiais e humanos, e ainda com pessoal não treinado; o trabalhador sente-se insatisfeito, com fadiga mental e física - situações que podem propiciar o aparecimento do estresse no desempenho das atividades laborais.

Evaluation of oxidative stress parameters and metabolic activities of nurses working day and night shifts

The aim of this study was to evaluate the oxidative stress and metabolic activities of nurses working day and night shifts. Intensive care unit (ICU) (n=70) and ordinary service (OS) nurses (n=70) were enrolled in the study. Just before and the end of the shifts, blood samples were obtained to measure the participants' oxidative stress parameters. Metabolic activities were analyzed using the SenseWear Armband. Oxidative stress parameters were increased at the end of the shifts for all OS and ICU nurses compared to the beginning of the shifts. Compared to the OS nurses, the ICU nurses' TAS, TOS, and OSI levels were not significantly different at the end of the day and night shifts. The metabolic activities of the OS and ICU nurses were found to be similar. As a result, the OS and ICU nurses' oxidative stress parameters and metabolic activities were not different, and all of the nurses experienced similar effects from both the day and night shifts.

Work-related stress according to the demand-control model and minor psychic disorders in nursing workers

This was a cross-sectional study that aimed to assess the association between work-related stress according to the Demand-Control Model, and the occurrence of Minor Psychic Disorder (MPD) in nursing workers. The participants were 335 professionals, out of which 245 were nursing technicians, aged predominantly between 20 and 40 years. Data were collected using the Job Stress Scale and the Self-Reporting Questionnaire-20. The analysis was performed using descriptive and analytical statistics. The prevalence of suspected MPD was 20.6%. Workers classified in the quadrants active job and high strain of the Demand-Control Model presented higher potential for developing MPD compared with those classified in the quadrant low strain. In conclusion, stress affects the mental health of workers and the aspects related to high psychological demands and high control still require further insight in order to understand their influence on the disease processes of nursing workers.

Stress among nurses: an examination of salivary cortisol levels on work and day off

The present study evaluates the use of salivary cortisol concentration as a physiological index of the stress level among nurses on their work day and day off and correlates it with the questionnaire used to measure occupational stress in nurses (Inventário de Estresse em Enfermeiros - IEE). This is a comparative, cross-sectional descriptive study in which sociodemographic data, IEE results and salivary cortisol levels were used. Fifty-seven nurses participated in the study (80.7% females and a mean age of 37.1 years old). The IEE average score was 124.5. The average cortisol level was 564.1 ng/m on work day and 354.1 ng/mL on day off. Nurses who had double workdays presented high values of salivary cortisol during the work day (638.1 ng/mL). In conclusion, salivary cortisol identified the nurses’ stress level, and differences were found between a work day and day off. On the nurses’ day off, their salivary cortisol levels and stress scores were lower.

Influence of stress factors and socio-demographic characteristics on the sleep quality of nursing students

Objective:To analyze the influence of stress factors and socio-demographic characteristics on the sleep quality of nursing students. Method: An analytical cross-sectional and quantitative study, conducted with 151 nursing students in São Paulo between March and April of 2012. A form for socio-demographic characteristics, the Instrument to Evaluate Stress in Nursing Students and the Pittsburgh Sleep Index were applied. Results: High levels of stress was predominant for Time Management (27.8%) and Professional Training (30.5%) and low sleep quality (78.8%). The Professional Communication, Professional Training and Theoretical Activity are positively correlated to sleep quality. Work activity, academic year and time for daily studies contributed to a low quality of sleep. Conclusion: Few stress factors from the academic environment and some socio-demographic characteristics contributed to the reduction of sleep quality in students.


Stress, coping and presenteeism in nurses assisting critical and potentially critical patients

Objective to verify the associations between stress, Coping and Presenteeism in nurses operating on direct assistance to critical and potentially critical patients. Method this is a descriptive, cross-sectional and quantitative study, conducted between March and April 2010 with 129 hospital nurses. The Inventory of stress in nurses, Occupational and Coping Questionnaire Range of Limitations at Work were used. For the analysis, the Kolmogorov-Smirnov test, correlation coefficient of Pearson and Spearman, Chi-square and T-test were applied. Results it was observed that 66.7% of the nurses showed low stress, 87.6% use control strategies for coping stress and 4.84% had decrease in productivity. Direct and meaningful relationships between stress and lost productivity were found. Conclusion stress interferes with the daily life of nurses and impacts on productivity. Although the inability to test associations, the control strategy can minimize the stress, which consequently contributes to better productivity of nurses in the care of critical patients and potentially critical.