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

Modeling HIV/AIDS Drug Price Determinants in Brazil: Is Generic Competition a Myth?

Brazil became the first developing country to guarantee free and universal access to HIV/AIDS treatment, with antiretroviral drugs (ARVs) being delivered to nearly 190,000 patients. The analysis of ARV price evolution and market dynamics in Brazil can help anticipate issues soon to afflict other developing countries, as the 2010 revision of the World Health Organization guidelines shifts demand towards more expensive treatments, and, at the same time, current evolution of international legislation and trade agreements on intellectual property rights may reduce availability of generic drugs for HIV care.Our analyses are based on effective prices paid for ARV procurement in Brazil between 1996 and 2009. Data panel structure was exploited to gather ex-ante and ex-post information and address various sources of statistical bias. In-difference estimation offered in-depth information on ARV market characteristics which significantly influence prices. Although overall ARV prices follow a declining trend, changing characteristics in the generic segment help explain recent increase in generic ARV prices. Our results show that generic suppliers are more likely to respond to factors influencing demand size and market competition, while originator suppliers tend to set prices strategically to offset compulsory licensing threats and generic competition.In order to guarantee the long term sustainability of access to antiretroviral treatment, our findings highlight the importance of preserving and stimulating generic market dynamics to sustain developing countries' bargaining power in price negotiations undertaken with originator companies

A large‐scale assessment of plant dispersal mode and seed traits across human‐modified Amazonian forests

1. Quantifying the impact of habitat disturbance on ecosystem function is critical to understanding and predicting the future of tropical forests. Many studies have examined post-disturbance changes in animal traits related to mutualistic interactions with plants, but the effect of disturbance on plant traits in diverse forests has received much less attention. 2. Focusing on two study regions in the eastern Brazilian Amazon, we used a trait-based approach to examine how seed dispersal functionality within tropical plant communities changes across a landscape-scale gradient of human modification, including both regenerating secondary forests and primary forests disturbed by burning and selective logging. 3. Surveys of 230 forest plots recorded 26,533 live stems from 846 tree species. Using herbarium material and literature, we compiled trait information for each tree species, focusing on dispersal mode and seed size. 4. Disturbance reduced tree diversity and increased the proportion of lower wood density and small-seeded tree species in study plots. Disturbance also increased the proportion of stems with seeds that are ingested by animals and reduced those dispersed by other mechanisms (e.g. wind). Older secondary forests had function-ally similar plant communities to the most heavily disturbed primary forests. Mean seed size and wood density per plot were positively correlated for plant species with seeds ingested by animals. 5. Synthesis. Anthropogenic disturbance has major effects on the seed traits of tree communities, with implications for mutualistic interactions with animals. The important role of animal-mediated seed dispersal in disturbed and recovering forests highlights the need to avoid defaunation or promote faunal recovery. The changes in mean seed width suggest larger vertebrates hold especially important functional roles in these human-modified forests. Monitoring fruit and seed traits can provide a valuable indicator of ecosystem condition, emphasizing the importance of developing a comprehensive plant traits database for the Amazon and other biomes