Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Hydroxyurea (HU) is the most important advance in the treatment of sickle cell anaemia (SCA) for preventing complications and improving quality of life for patients. However, some aspects of treatment with HU remain unclear, including their effect on and potential toxicity to other blood cells such as neutrophils. This study used the measurement of Lactate Dehydrogenase (LDH) and Methyl ThiazolTetrazolium (MTT) and the comet assay to investigate the cytotoxicity and damage index (DI) of the DNA in the neutrophils of patients with SCA using HU.In the LDH and MTT assays, a cytoprotective effect was observed in the group of patients treated, as well as an absence of toxicity. When compared to patients without the treatment, the SS group (n=20, 13 women and 07 men, aged 18-69 years), and the group of healthy individuals (AA) used as a control group (n=52, 28 women and 24 men, aged 19-60 years), The SSHU group (n=21, 11 women and 10 men, aged 19-63 years) showed a significant reduction (p20 months), demonstrating that despite the cytoprotective effects in terms of cell viability, the use of HU can induce DNA damage in neutrophils

Molecular mechanisms involved in the control of neutrophil apoptosis

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The Obsessive Beliefs Questionnaire (OBQ) : Examination in nonclinical samples and development of a short version

The study aimed to examine the factor structure of the Obsessive Beliefs Questionnaire (OBQ), the most widely used measure of dysfunctional beliefs in obsessive—compulsive disorder (OCD). Multiple exploratory methods (exploratory factor analysis, cluster analysis by variable, multidimensional scaling) were used to examine the questionnaire. Confirmatory factor analyses were also performed in two large nonclinical samples from Australia (N = 1,234) and Israel ( N = 617). Our analyses suggested a four-factor solution with 38 items, where threat and responsibility formed separate dimensions (the “OBQ-TRIP”). This version had superior fit statistics across the two divergent confirmatory samples, when compared with four alternative models suggested by previous authors. Of the OBQ dimensions, the threat scale correlated most strongly with OCD symptom measures, even when controlling for depression. A short, 20-item version of the scale is offered for further study. Implications and limitations are discussed

Staphylococcus aureus alpha-toxin induces apoptosis in peripheral blood mononuclear cells:role of endogenous tumour necrosis factor-alpha and the mitochondrial death pathway

Staphylococcus aureus infections can result in septic and toxic shock with depletion of immune cells and massive cytokine production. Recently, we showed that, in S. aureus-infected Jurkat T cells, alpha-toxin is the major mediator of caspase activation and apoptosis. Here, we investigated the mechanisms of cell death induced by alpha-toxin in peripheral blood mononuclear cells (MNC). We show that alpha-toxin is required and sufficient for S. aureus-induced cell death not only in transformed Jurkat T cells but also in MNC. Low alpha-toxin doses (3-30 ng ml-1) dose- and time-dependently induced apoptosis in both cell types, which was completely blocked by the caspase inhibitor zVAD-fmk. In Jurkat T cells and MNC, alpha-toxin induced the breakdown of the mitochondrial membrane potential and the intrinsic activation of caspase-3, -8 and -9. Interestingly, unlike in Jurkat T cells, apoptosis in MNC was additionally mediated by a caspase-9-independent component. MNC, but not Jurkat T cells, produced tumour necrosis factor (TNF)-alpha upon alpha-toxin stimulation. Blocking endogenous TNF-alpha with a TNF-alpha receptor antagonist partially decreased apoptosis in MNC. Our data therefore suggest that, whereas in Jurkat T cells apoptosis is solely mediated by the mitochondrial pathway, in MNC endogenous TNF-alpha and a death receptor-dependent pathway are also involved, which may contribute to depletion of immune cells during S. aureus infection