Trypanosoma cruzi: The effects of zinc supplementation in the immune response during the course of experimental disease

Zinc is an essential nutritional component required for normal development and maintenance of immune functions. The possible effects of zinc in upregulating the host immune response during the acute and chronic phases of experimental Chagas` disease were evaluated. In young, infected and Zn-supplemented animals, higher concentrations of IFN-gamma and NO were observed. During the chronic phase, decreased concentrations of NO and IFN-gamma were found for older infected animals that received Zn supplementation. For young animals, hearts from Zn-supplemented groups displayed reduced inflammatory infiltrate, heart weight and number of amastigote burdens. For older, infected and Zn-supplemented animals amastigote nests were absent with reduced inflammatory cell infiltrate. This study identifies a potentially novel therapeutic approach that could control the parasite load during acute phase of disease, consequently preventing the deleterious, parasite-elicited responses observed during chronic phase. (C) 2008 Elsevier Inc. All rights reserved.

Effects of repetitive stress during the acute phase of Trypanosoma cruzi infection on chronic Chagas` disease in rats

The effect of repetitive stress during acute infection with Trypanosoma cruzi (T. cruzi) on the chronic phase of ensuing Chagas` disease was the focus of this investigation. The aim of this study was to evaluate in Wistar rats the influence of repetitive stress during the acute phase of infection (7 days) with the Y strain of T. cruzi on the chronic phase of the infection (at 180 days). Exposure to ether vapor for 1min twice a day was used as a stressor. Repetitive stress enhanced the number of circulating parasites and cardiac tissue disorganization, from a moderate to a severe diffuse mononuclear inflammatory process and the presence of amastigote burden in the cardiac fibers. Immunological parameters revealed that repetitive stress triggered a reduced concanavalin A induced splenocyte proliferation in vitro with major effects on the late chronic phase. Serum interleukin-12 concentration decreased in both stressed and infected rats in the early phase of infection although it was higher on 180 days post-infection. These results suggest that repetitive stress can markedly impair the host`s immune system and enhance the pathological process during the chronic phase of Chagas` disease.

Melatonin enhances pro-inflammatory cytokine levels and protects against Chagas disease

Pro-inflammatory and modulatory cytokines have an essential role in host defense against human and murine Trypanosoma cruzi infection. Control of T. cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. Melatonin has been proposed to regulate the immune system by affecting cytokine production in immunocompetent cells, enhancing the production of several T helper (Th)1 cytokines. The aims of this work were to evaluate in rats, the influences of exogenous melatonin treatment on T. cruzi-infected host`s immune responses. With this in mind, several immunological parameters were analyzed, including tumor necrosis factor-alpha, gamma-interferon, interleukin-12, nitric oxide (NO) and macrophage count. The melatonin therapy was provided in one of two different treatment regimens, that is, either beginning 7 days prior to infection or concomitant with the infection. Both treatments triggered an up-regulation of the immune response, with the concomitant treatment being more effective; in this case all cytokines studied, with exception of NO, displayed enhanced concentrations and there was a higher number of peritoneal macrophages, which displayed reduced concentrations under melatonin therapy. We conclude that melatonin plays a pivotal role in up-regulating the Th1 immune response thus controlling parasite replication.

Sensitivity to cisplatin-induced mutations and elevated chromosomal aberrations in lymphocytes from sickle cell disease patients

Sickle cell disease (SCD) is an inherited disorder caused by a single nucleotide substitution in the P-globin gene. The clinical heterogeneity observed in SCD patients has been attributed to environmental and genetic factors. The patients are subjected to increased oxidative stress, particularly during vaso-occlusive crises and acute chest pain. Another possible cause of oxidative stress in SCD is the high concentration of iron in the patients` plasma. The increase in oxidative stress could be a relevant risk factor for mutagenesis and carcinogenesis. Studies on the frequency of basal chromosomal aberrations in cultured lymphocytes from SCD patients have not been reported so far. In order to contribute to the understanding of the role of the different biomarkers and their relationship with the extremely variable clinical manifestation of SCD, we investigated the frequency of chromosome damage in peripheral lymphocytes from sickle cells patients and healthy controls. We found an increased frequency of chromosome damage and percentage of aberrant metaphases in these patients when compared with control subjects, even at basal values (p < 0.05). In the cytogenetic sensitivity assay, the results showed that these patients presented a marked decrease in the mitotic index values compared with healthy controls. Cisplatin-induced chromosomal damage in lymphocytes from these patients was significantly higher than the frequency measured in healthy controls. The results obtained in the present study showed that more investigations are needed in order to elucidate the susceptibility to genomic instability of SCD patients.

Evaluation of Environmental Mycobacteria Contamination in a Specific Pathogen Free Animal Facility from a Tropical Country

P>With the evidence showing the protection variability of bacille Calmette-Guerin, new potential vaccines for tuberculosis have been tested around the world. One of the general concerns in tuberculosis vaccine development is the possibility of priming the host immune system with prior exposure to environmental mycobacteria antigens, which can change the efficacy of subsequent vaccination. As there is a great homology between the species from Mycobacterium genera, the previous contact of experimental animals with environmental mycobacteria could sensitize the mice and, in this way, could influence subsequent vaccine research. The aim of our study was to investigate critical points in an animal facility to search for environmental mycobacteria that eventually could be in direct or indirect contact with the experimental animals. Samples were collected from surfaces of walls, floor, animal cages and shelves and analysed using the Ogawa-Kudoh decontamination method. Samples of drinking water, food and sawdust were collected for analysis by the NALC/NaOH decontamination method. Also, the samples were cultivated directly in broth medium, without any method for decontamination. After decontamination methods, we observed bacterial colony growth in 4.31% of the total of samples analysed. These samples were stained with Ziehl-Neelsen and we did not detect any acid-fast bacilli, suggesting that the animal facility analysed is free from contamination by environmental mycobacteria and is not a source of mycobacterial antigens. Furthermore, our study showed a new paradigm in tuberculosis vaccine development: concern about the animal facility environment in terms of immune system priming of experimental animals by nascent bacterial contaminants.

New method for quantification of Trypanosoma cruzi in animal`s tissue in the chronic phase of experimental Chagas` disease

We developed a new method for the quantification of parasites in tissue. Trypanosoma cruzi strain CL parasites were genetically engineered to express the Escherichia coli beta-galactosidase gene, lacZ and this enzyme is able to catalyze a colorimetric reaction with chlorophenol red beta-d galactopyranoside (CPRG) as the substrate. The animals were infected with clone CL Brener strain B5 of T. cruzi and treated with benznidazole in order to verify the reduction in the number of parasites in tissue study by quantifying the enzyme beta-galactosidase. The assay demonstrates a reduction in the number of parasites in the groups treated. Thus, this test can be used to test other substances with the aim of verifying the effectiveness in the chronic phase of experimental Chagas` disease.

Experimental Chagas` disease in orchiectomized Calomys callosus infected with the CM strain of Trypanosoma cruzi

The incidence and progression of disorders associated with an unbalanced immune response has among many factors the gender as a contributory factor. The aims of this work were to evaluate the effects of orchiectomy and the immune response during the experimental Trypanosoma cruzi infection. Young adult, male Calomys callous were i.p. inoculated with 1 x 10(5) blood trypomastigotes of the CM strain of T. cruzi and divided in groups: Control, Sham and Castrated. Castrated group displayed significantly lower values for prostate and seminal vesicle weights indicating a drastic drop of testosterone plasmatic levels. Orchiectomized animals also displayed lesser number of blood parasites, enhanced lytic antibody percentage, splenocyte proliferation and NO concentration when compared to its sham and control counterparts, indicating that steroid gonadal ablation actually influences immune response triggering a more efficient cellular and humoral response which led animals to become more resistant against T cruzi infection. (C) 2009 Elsevier Inc. All rights reserved.

Circulating matrix metalloproteinase-8 (MMP-8) and MMP-9 are increased in chronic periodontal disease and decrease after non-surgical periodontal therapy

Background: Periodontal disease shares risk factors with cardiovascular diseases and other systemic inflammatory diseases. The present study was designed to assess the circulating matrix metalloproteinases (MMPs) from chronic periodontal disease patients and, subsequently, after periodontal therapy. Methods: We compared the plasma concentrations of MMP-2. MMP-3, MMP-8, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2, and total gelatinolytic activity in patients with periodontal disease (n =28) with those of control subjects (n = 22) before and 3 months after non-surgical periodontal therapy. Results: Higher plasma MMP-3, MMP-8, and MMP-9 concentrations were found in periodontal disease patients compared with healthy controls (all P<0.05), whereas MMP-2, TIMP-1, and TIMP-2 levels were not different. Treatment decreased plasma MMP-8 and MMP-9 concentrations by 35% and 39%, respectively (both P<0.02), while no changes were found in controls. MMP-2, MMP-3, TIMP-1, and TIMP-2 remained unaltered in both groups. Plasma gelatinolytic activity was higher in periodontal disease patients compared with controls (P<0.001) and decreased after periodontal therapy (P<0.05). Conclusions: This study showed increased circulating MMP-8 and MMP-9 levels and proteolytic activity in periodontal disease patients that decrease after periodontal therapy. The effects of periodontal therapy suggest that it may attenuate inflammatory chronic diseases. (C) 2009 Published by Elsevier B.V.

Trypanosoma cruzi: Dehydroepiandrosterone (DHEA) and immune response during the chronic phase of the experimental Chagas` disease

Dehydroepiandrosterone (DHEA) has long been considered as a precursor for many steroid hormones. It also enhances the immune responses against a wide range of viral, bacterial, and parasitic pathogens. The aims of this work were to evaluate the influences of exogenous DHEA treatment on Wistar rats infected with the Y strain of Trypanosoma cruzi during the acute and its influence on the chronic phase of infection. Animals were subcutaneous treated with 40 mg/kg body weight/day of DHEA. DHEA treatment promoted increased lymphoproliferative responses as well as enhanced concentrations of NO and IL-12. So, we point in the direction that our results validate the utility of the use of DHEA as an alternative therapy candidate against T cruzi. (C) 2009 Published by Elsevier B.V.

Thermal Characteristics of Polybia scutellaris Nests (Hymenoptera: Vespidae) Using Computational Fluid Dynamics: A Possible Adaptation to Tropical Climates

Polybia scutellaris constructs huge nests characterized by numerous spinal projections on the surface. We investigated the thermal characteristics of P scutellaris nests in order to determine whether their nest temperature is homeothermically maintained and whether the spines play a role in the thermoregulation of the nests. In order to examine these hypotheses, we measured the nest temperature in a active nest and in an abandoned nest. The temperature in the active nest was almost stable at 27 degrees C, whereas that of the abandoned nest varied with changes in the ambient temperature, suggesting that nest temperature was maintained by the thermogenesis of colony individuals. In order to predict the thermal properties of the spines, a numerical simulation was employed. To construct a 3D-model of a P scutellaris nest, the nest architecture was simplified into an outer envelope and the surface spines, for both of which the initial temperature was set at 27 degrees C. The physical properties of the simulated nest were regarded to be those of wood since the nest of this species is constructed from plant materials. When the model was exposed to cool air (12 degrees C), the temperature was lower in the models with more spines. On the other hand, when the nest was heated (42 degrees C), the temperature increase was smaller in models with more spines. It is suggested that the spines act as a heat radiator, not as an insulator, against the changes in ambient temperature.

Differential responses of antioxidant enzymes in pioneer and late-successional tropical tree species grown under sun and shade conditions

To investigate the ability of pioneer and late-successional species to adapt to a strong light environment in a reforestation area, we examined the activities of antioxidant enzymes in relation to photosystem chlorophyll a fluorescence and photosynthetic pigment concentration for eight tropical tree species grown under 100% (sun) and 10% (shade) sunlight irradiation. The pioneer (early-succession) species (PS) were Cecropia pachystachya, Croton urucurana, Croton floribundus and Schinus terebinthifolius. The non-pioneer (late succession) species (LS) were Hymenaea courbaril L var. stilbocarpa, Esenbeckia leiocarpa, Cariniana legalis and Tabebuia roseo-alba. We observed a greater decline in the ratio of variable to maximum chlorophyll a fluorescence (F(v)/F(m)) under full sunlight irradiation in the late-successional species than in the pioneer species. The LS species most sensitive to high irradiance were C. legalis and H. courbaril. In LS species, chlorophyll a, chlorophyll b and total chlorophyll concentrations were higher in the shade-grown plants than in plants that developed under full sunlight, but in the PS species C. floribundus and C. pachystachya, we did not observe significant changes in chlorophyll content when grown in the two contrasting environments. The carotenoids/total chlorophyll ratio increased significantly when plants developed under high-sunlight irradiation, but this response was not observed in the PS species S. terebinthifolius and C. pachystachya. The improved performance of the pioneer species in high sunlight was accompanied by an increase in superoxide dismutase (SOD. EC 1.15.1.1) activity, though no light-dependent increase in the activity of ascorbate peroxidase (APX. EC 1.11.1.11) was observed. The activity of catalase (CAT, EC 1.11.1.6) was reduced by high irradiation in both pioneer and late-successional species. Our results show that pioneer species perform better under high-sunlight irradiation than late-successional species, as indicated by increased SOD activity and a higher F IF,, ratio. C. legalis was the LS species most susceptible to photoinhibition under full sunlight conditions. These results suggest that pioneer plants have more potential tolerance to photo-oxidative damage than late-successional species associated with the higher SOD activity found in pioneer species. Reduced photoinhibition in pioneer species probably results from their higher photosynthetic capacities, as has been observed in a previous survey carried out by our group. (C) 2010 Elsevier B.V. All rights reserved.

Dyslipidemia in a Cohort of HIV-infected Latin American Children Receiving Highly Active Antiretroviral Therapy*

In order to describe the prevalence of hypercholesterolemia and hypertriglyceridemia in a cohort of HIV-infected children and adolescents in Latin America and to determine associations with highly active antiretroviral therapy (HAART), we performed this cross-sectional analysis within the NICHD International Site Development Initiative pediatric cohort study. Eligible children had to be at least 2 years of age and be on HAART. Among the 477 eligible HIV-infected youth, 98 (20.5%) had hypercholesterolemia and 140 (29.4%) had hypertriglyceridemia. In multivariable analyses, children receiving protease inhibitor (PI)-containing HAART were at increased risk for hypercholesterolemia [adjusted odds ratio (AOR) = 2.7, 95% confidence interval (CI) 1.3-5.6] and hypertriglyceridemia (AOR = 3.5, 95% CI 1.9-6.4) compared with children receiving non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing HAART. In conclusion, HIV-infected youth receiving PI-containing HAART in this Latin American cohort were at increased risk for hypercholesterolemia and hypertriglyceridemia compared with those receiving NNRTI-containing HAART.

Prognostic Significance of Myocardial Fibrosis Quantification by Histopathology and Magnetic Resonance Imaging in Patients With Severe Aortic Valve Disease

Objectives We sought to determine whether the quantitative assessment of myocardial fibrosis (MF), either by histopathology or by contrast-enhanced magnetic resonance imaging (ce-MRI), could help predict long-term survival after aortic valve replacement. Background Severe aortic valve disease is characterized by progressive accumulation of interstitial MF. Methods Fifty-four patients scheduled to undergo aortic valve replacement were examined by ce-MRI. Delayed-enhanced images were used for the quantitative assessment of MF. In addition, interstitial MF was quantified by histological analysis of myocardial samples obtained during open-heart surgery and stained with picrosirius red. The ce-MRI study was repeated 27 +/- 22 months after surgery to assess left ventricular functional improvement, and all patients were followed for 52 +/- 17 months to evaluate long-term survival. Results There was a good correlation between the amount of MF measured by histopathology and by ce-MRI (r = 0.69, p < 0.001). In addition, the amount of MF demonstrated a significant inverse correlation with the degree of left ventricular functional improvement after surgery (r = -0.42, p = 0.04 for histopathology; r = -0.47, p = 0.02 for ce-MRI). Kaplan-Meier analyses revealed that higher degrees of MF accumulation were associated with worse long-term survival (chi-square = 6.32, p = 0.01 for histopathology; chi-square = 5.85, p = 0.02 for ce-MRI). On multivariate Cox regression analyses, patient age and the amount of MF were found to be independent predictors of all-cause mortality. Conclusions The amount of MF, either by histopathology or by ce-MRI, is associated with the degree of left ventricular functional improvement and all-cause mortality late after aortic valve replacement in patients with severe aortic valve disease. (J Am Coll Cardiol 2010; 56: 278-87) (c) 2010 by the American College of Cardiology Foundation

Pulmonary Hypertension in Latin America Pulmonary Vascular Disease: The Global Perspective

Latin America is here defined as all of the Americas south of the United States. In the setting of pulmonary hypertension, there are social inequalities and geophysical aspects in this region that account for a high prevalence of certain etiologies. This review aimed to analyze some of these factors. Data were collected from the existing literature. Information also was obtained from local tertiary-care centers to where patients with pulmonary hypertension generally are referred. Further, local experience and expertise was taken into consideration. Three etiologies of pulmonary hypertension were found to be the most prevalent: schistosomiasis (similar to 1 million affected people in Brazil), high altitude (particularly in the Andes), and congenital heart disease (late diagnosis of congenital left-to-right shunts leading to development of pulmonary vasculopathy). The diversity in terms of ancestries and races probably accounts for the differences in phenotype expression of pulmonary hypertension when a given region is considered (eg, schistosomiasis-, high-altitude-, or congenital heart disease-associated pulmonary hypertension). Governmental measures are needed to improve social and economic inequalities with an obvious impact on certain etiologies, such as schistosomiasis and congenital heart disease. Early diagnosis of pulmonary hypertension and access to medication remain important challenges all over Latin America. CHEST 2010; 137(6)(Suppl):78S-84S

The impact of simple donor education on donor behavioral deferral and infectious disease rates in Sao Paulo, Brazil

BACKGROUND: Studies have shown that human immunodeficiency virus (HIV) residual risk is higher in Brazilian than in US and European blood donors, probably due to failure to defer at-risk individuals in Brazil. This study assessed the impact of an educational brochure in enhancing blood donors` knowledge about screening test window phase and reducing at-risk individuals from donating. STUDY DESIGN AND METHODS: This trial compared an educational intervention with a blood center`s usual practice. The brochure was distributed in alternating months to all donors. After donating, sampled participants completed two questions about their HIV window period knowledge. The impact on HIV risk deferral, leaving without donation, confidential unit exclusion (CUE) use, and test positivity was also analyzed. RESULTS: From August to November 2007 we evaluated 33,940 donations in the main collection center of Fundacao Pro-Sangue/Hemocentro de Sao Paulo in Sao Paulo, Brazil. A significant (p < 0.001) pamphlet effect was found on correct responses to both questions assessing HIV window phase knowledge (68.1% vs. 52.9%) and transfusion risk (91.1% vs. 87.2%). After adjusting for sex and age, the pamphlet effect was strongest for people with more than 8 years of education. There was no significant pamphlet effect on HIV risk deferral rate, leaving without donation, use of CUE, or infectious disease rates. CONCLUSION: While the educational pamphlet increased window period knowledge, contrary to expectations this information alone was not enough to make donors self-defer or acknowledge their behavioral risk.