Inducible Nitric Oxide Synthase in Heart Tissue and Nitric Oxide in Serum of Trypanosoma cruzi-Infected Rhesus Monkeys: Association with Heart Injury

Chagas disease, a neglected tropical disease caused by the protozoan Trypanosoma cruzi, afflicts from 8 to 15 million people in the Latin America. Chronic chagasic cardiomyopathy (CCC) is the most frequent manifestation of Chagas disease. Currently, patient management only mitigates CCC symptoms. The pathogenic factors leading to CCC remain unknown; therefore their comprehension may contribute to develop more efficient therapies. In patients, high nitric oxide (NO) levels have been associated with CCC severity. In T. cruzi-infected mice, NO, mainly produced via inducible nitric oxide synthase (iNOS/NOS2), is proposed to work in parasite control. However, the participation of iNOS/NOS2 and NO in T. cruzi control and heart injury has been questioned. Here, infected rhesus monkeys and iNOS/NOS2-deficient mice were used to explore the participation of iNOS/NOS2-derived NO in heart injury in T. cruzi infection. Chronically infected monkeys presented electrical abnormalities, myocarditis and fibrosis, resembling the spectrum of human CCC. Moreover, cardiomyocyte lesion correlated with iNOS/NOS2+ cells infiltrating the cardiac tissue. Our findings support that parasite-driven iNOS/NOS2+ cells accumulation in the cardiac tissue and NO overproduction contribute to cardiomyopathy severity, mainly disturbing the pathway involved in electrical synchrony in T. cruzi infection

CD8+ T-Cells Expressing Interferon Gamma or Perforin Play Antagonistic Roles in Heart Injury in Experimental Trypanosoma Cruzi-Elicited Cardiomyopathy

In Chagas disease, CD8+ T-cells are critical for the control of Trypanosoma cruzi during acute infection. Conversely, CD8+ T-cell accumulation in the myocardium during chronic infection may cause tissue injury leading to chronic chagasic cardiomyopathy (CCC). Here we explored the role of CD8+ T-cells in T. cruzi-elicited heart injury in C57BL/6 mice infected with the Colombian strain. Cardiomyocyte lesion evaluated by creatine kinase-MB isoenzyme activity levels in the serum and electrical abnormalities revealed by electrocardiogram were not associated with the intensity of heart parasitism and myocarditis in the chronic infection. Further, there was no association between heart injury and systemic anti-T. cruzi CD8+ T-cell capacity to produce interferon-gamma (IFNγ) and to perform specific cytotoxicity. Heart injury, however, paralleled accumulation of anti-T. cruzi cells in the cardiac tissue. In T. cruzi infection, most of the CD8+ T-cells segregated into IFNγ+ perforin (Pfn)neg or IFNγnegPfn+ cell populations. Colonization of the cardiac tissue by anti-T. cruzi CD8+Pfn+ cells paralleled the worsening of CCC. The adoptive cell transfer to T. cruzi-infected cd8−/− recipients showed that the CD8+ cells from infected ifnγ−/−pfn+/+ donors migrate towards the cardiac tissue to a greater extent and caused a more severe cardiomyocyte lesion than CD8+ cells from ifnγ+/+pfn−/− donors. Moreover, the reconstitution of naïve cd8−/− mice with CD8+ cells from naïve ifnγ+/+pfn−/− donors ameliorated T. cruzi-elicited heart injury paralleled IFNγ+ cells accumulation, whereas reconstitution with CD8+ cells from naïve ifnγ−/−pfn+/+ donors led to an aggravation of the cardiomyocyte lesion, which was associated with the accumulation of Pfn+ cells in the cardiac tissue. Our data support a possible antagonist effect of CD8+Pfn+ and CD8+IFNγ+ cells during CCC. CD8+IFNγ+ cells may exert a beneficial role, whereas CD8+Pfn+ may play a detrimental role in T. cruzi-elicited heart injury

Controversies in the management of advanced prostate cancer

For advanced prostate cancer, the main hormone treatment against which other treatments are assessed is surgical castration. It is simple, safe and effective, however it is not acceptable to all patients. Medical castration by means of luteinizing hormone-releasing hormone (LH-RH) analogues such as goserelin acetate provides an alternative to surgical castration. Diethylstilboestrol, previously the only non-surgical alternative to orchidectomy, is no longer routinely used. Castration reduces serum testosterone by around 90%, but does not affect androgen biosynthesis in the adrenal glands. Addition of an anti-androgen to medical or surgical castration blocks the effect of remaining testosterone on prostate cells and is termed combined androgen blockade (CAB). CAB has now been compared with castration alone (medical and surgical) in numerous clinical trials. Some trials show advantage of CAB over castration, whereas others report no significant difference. The author favours the view that CAB has an advantage over castration. No study has reported that CAB is less effective than castration. Of the anti-androgens which are available for use in CAB, bicalutamide may be associated with a lower incidence of side-effects compared with the other non-steroidal anti-androgens and, in common with nilutamide, has the advantage of once-daily dosing. Only one study has compared anti-androgens within CAB: bicalutamide plus LH-RH analogue and flutamide plus LH-RH analogue. At 160-week follow-up, the groups were equivalent in terms of survival and time to progression. However, bicalutamide caused significantly less diarrhoea than flutamide. Withdrawal and intermittent therapy with anti-androgens extend the range of treatment options. © 1999 Cancer Research Campaig

Application of toxicity identification evaluation to sediment in a highly contaminated water reservoir in southeastern Brazil

Rasgao Reservoir, located close to the Metropolitan region of Sao Paulo, Brazil, has been analyzed previously, and its sediment was found to be highly toxic, with high levels of metals and polycyclic aromatic hydrocarbons and a complete absence of benthic life. Polychlorinated biphenyls also were present, as was mutagenic activity, detected with the Salmonella/microsome assay. Because of the extremely complex mixture of contaminants in these sediments, a toxicity identification evaluation was performed on the pore water and elutriate using Ceriodaphnia dubia and Vibrio fischeri. Toxicity characterization, identification, and confirmation procedures were performed in one representative sample of the reservoir, and the results indicated that ammonia was the main cause of the toxicity detected with C. dubia in both sediment pore water and elutriate. Chemical analysis corroborated this observation by revealing un-ionized ammonia concentrations as high as 5.14 mg/L in pore water and 2.06 mg/L in elutriate. These high ammonia levels masked possible toxicity caused by other classes of compounds. The toxicity detected with V. fischeri decreased with the time of sample storage and was related to the organic fraction of the pore water and the elutriate, in which compounds such as benzothiazole and nonylphenol were detected.25258158