A Mg-dependent ecto-ATPase is increased in the infective stages of<Emphasis Type="Italic"> Trypanosoma cruzi</Emphasis>

In this work, we describe the ability of living epimastigotes of Trypanosoma cruzi to hydrolyze extracellular ATP. In these intact parasites, there was a low level of ATP hydrolysis in the absence of any divalent metal (2.42±0.31 nmol Pi/h×10⁸ cells). ATP hydrolysis was stimulated by MgCl₂, and the Mg-dependent ecto-ATPase activity was 27.15±2.91 nmol Pi/h×10⁸ cells. The addition of MgCl₂ to the extracellular medium increased the ecto-ATPase activity in a dose-dependent manner. This stimulatory activity was also observed when MgCl₂ was replaced by MnCl₂, but not by CaCl₂ or SrCl₂. The apparent K_m for Mg-ATP^2– was 0.61 mM, and free Mg²⁺ did not increase the ecto-ATPase activity. This ecto-ATPase activity was insensitive to the inhibitors of other ATPase and phosphatase activities. To confirm that this Mg-dependent ATPase was an ecto-ATPase, we used an impermeant inhibitor, DIDS (4, 4.diisothiocyanostylbene 2-2-disulfonic acid) as well as suramin, an antagonist of P₂ purinoreceptors and inhibitor of some ecto-ATPases. These two reagents inhibited the Mg²⁺-dependent ATPase activity in a dose-dependent manner. A comparison among the Mg²⁺-ecto-ATPase activities of the three forms of T. cruzi showed that the noninfective epimastigotes were less efficient at hydrolyzing ATP than the infective trypomastigote and amastigote stages.     

The time course of vasoconstriction and endothelin receptor A expression in pulmonary arterioles of mice continuously exposed to ambient urban levels of air pollution

The present study aimed to verify the time course of the effects of environmental levels of urban air pollution toxicity on lung arterioles. BALB/c mice (n=56) were continuously exposed to selective chambers equipped with (filtered, F) or without (non-filtered, NF) filter devices for particles and toxic gases for 24 h/day, over 14, 21, 30 or 45 days. After exposure, we evaluated the lumen-wall relationship (an estimator of arteriolar narrowing), endothelial nitric oxide synthase (eNOS) and endothelin type A receptor (ETAr) expression in the vascular wall and inflammatory influx of the peribronchiolar area. Concentrations of fine particulate matter (PM≤2.5 μg/m³), nitrogen dioxide (NO₂), black smoke (BS), humidity and temperature in both the environment and inside the chambers were measured daily. Filters cleared 100% of BS and 97% of PM inside the F chamber. The arteriole wall of the lungs of mice from NF chamber had an increased ETAr expression (p≤0.042) concomitant to a decrease in the lumen/wall ratio (p=0.02) on the early days of exposure, compared to controls. They also presented a progressive increment of inflammatory influx in the peribronchiolar area during the study (p=0.04) and decrement of the eNOS expression on the 45th day of exposure in both vascular layers (p≤0.03). We found that after 14 days of exposure, the ambient levels of air pollutants in Sao Paulo induced vasoconstriction that was associated with an increase in ETAr expression. These vascular results do not appear to be coupled to the progressive inflammatory influx in lung tissue, suggesting a down-regulation of vasoconstrictive mechanisms through an imbalance in the cytokines network. It is likely that these responses are protective measures that decrease tissue damage brought about by continuous exposure to air pollutants.     

Missed diagnosis in hematological patients—an autopsy study

Autopsy findings of missed diagnoses that would probably have changed management or prognosis occur in up to 29% of cases in general hospitals. Such proportions may be higher in subsets of patients with complex diseases. We reviewed 2908 consecutive autopsies performed over a period of 29 months in a large-volume hospital, analyzing 118 autopsies of patients with hematological malignancies or severe aplastic anemia. A review of macroscopic reports as well as microscopic examination of tissue samples was performed. Medical records were reviewed for clinical diagnoses. Discordances between clinical and autopsy diagnoses were classified using Goldmans criteria. Additionally, we searched for clinical parameters correlated with occurrence of class-I discrepancy using a multivariate method. Median age was 46.5 years, and 25.4% had received a hematopoietic stem-cell transplant. Overall, 11.9% (6.6–19.1%) of patients died before conclusion of the hematological diagnosis and 33% (24.6–42.3%) died with no active hematological disease. We found class-I discrepancy in 31.3% (23.1–40.5 %) of cases. The most common among these diagnoses were hematological disease, pneumonia and gastrointestinal bleeding. In a univariate analysis, being elderly (P=0.04) was positively correlated with the finding of class-I discrepancies; while, having received previous specific hematological treatment (P=0.0005) or hematopoietic stem-cell transplants (P=0.013), or being admitted to a specialized hematology unit (P=0.0006) were negatively correlated to the occurrence of such discrepancies. Multivariate analysis showed that care in a specialized hematology unit (OR 0.34, 0.12–0.93) was independently associated with lower occurrence of discrepancies. We concluded that critical diagnoses are often missed in highly complex hematological patients especially in the absence of admission to specialized hematology units.     

Effect of acute swimming exercise at different intensities but equal total load over metabolic and molecular responses in swimming rats

Journal of Muscle Research and Cell Motility - Acute metabolic and molecular response to exercise may vary according to exercise’s intensity and duration. However, there is a lack regarding...     

Utilization of the lower inflection point of the pressure-volume curve results in protective conventional ventilation comparable to high frequency oscillatory ventilation in an animal model of acute respiratory distress syndrome

INTRODUCTION: Studies comparing high frequency oscillatory and conventional ventilation in acute respiratory distress syndrome have used low values of positive end-expiratory pressure and identified a need for better recruitment and pulmonary stability with high frequency. OBJECTIVE: To compare conventional and high frequency ventilation using the lower inflection point of the pressure-volume curve as the determinant of positive end-expiratory pressure to obtain similar levels of recruitment and alveolar stability. METHODS: After lung lavage of adult rabbits and lower inflection point determination, two groups were randomized: conventional (positive end-expiratory pressure = lower inflection point; tidal volume=6 ml/kg) and high frequency ventilation (mean airway pressures= lower inflection point +4 cmH2O). Blood gas and hemodynamic data were recorded over 4 h. After sacrifice, protein analysis from lung lavage and histologic evaluation were performed. RESULTS: The oxygenation parameters, protein and histological data were similar, except for the fact that significantly more normal alveoli were observed upon protective ventilation. High frequency ventilation led to lower PaCO2 levels. DISCUSSION: Determination of the lower inflection point of the pressure-volume curve is important for setting the minimum end expiratory pressure needed to keep the airways opened. This is useful when comparing different strategies to treat severe respiratory insufficiency, optimizing conventional ventilation, improving oxygenation and reducing lung injury. CONCLUSIONS: Utilization of the lower inflection point of the pressure-volume curve in the ventilation strategies considered in this study resulted in comparable efficacy with regards to oxygenation and hemodynamics, a high PaCO2 level and a lower pH. In addition, a greater number of normal alveoli were found after protective conventional ventilation in an animal model of acute respiratory distress syndrome.     

Prevalence of viral hepatitis B and C in riverside communities of the Tucuruí Dam,Pará, Brazil

Epidemiologically, the relevance of infection caused by hepatitis viruses is related mainly to their wide geographic distribution and the large number of infected individuals in all parts of the world. In this study, 668 residents from the islands around the Tucuruí Dam were selected. Blood samples were collected for investigation of serological markers (HBsAg, total anti‐HBc, anti‐HBS, and anti‐HCV) by enzyme immunoassays. HCV‐positive subjects were tested using RT‐PCR and RFLP for the identification of viral genotypes. Among the 668 subjects studied, 1.9% were HBsAg positive, 28% were total anti‐HBc positive, and 41.9% were anti‐HBs positive. The anti‐HBs marker alone (vaccine response) was detected in 25.7% of the volunteers. Anti‐HCV antibody was detected in 2.2% of the subjects and genotype 1 was the predominant genotype (70%). The results indicate an intermediate level of HBV and HCV endemicity in the region studied, as well as low HBV vaccination coverage. J. Med. Virol. 84:1907–1912, 2012. © 2012 Wiley Periodicals, Inc.     

Sperm morphological abnormalities visualised at high magnification predict embryonic development,from fertilisation to the blastocyst stage,in couples undergoing ICSI

PurposeTo investigate the predictive value of the motile sperm organelle morphology examination (MSOME) on embryo morphology.MethodsThe morphologies of 540 embryos obtained from 60 couples undergoing ICSI were evaluated from days 1 to 5 of development and were examined for associations with the percentages of morphologically normal paternal sperm and of the paternal sperm with large nuclear vacuoles (LNVs) as determined by MSOME.ResultsAn increased percentage of LNV sperm was associated with increased odds of a zygote presenting with pronuclear abnormalities. It was also associated with decreased odds of (i) normal cleavage on days 2 and 3 of development, (ii) the presence of a high-quality embryo on day 3, (iii) the development of an embryo to the blastocyst stage, and (iv) an embryo possessing a normal trophectoderm and inner cell mass. The calculated areas under the curves differed for the embryos that did and did not develop to the blastocyst stage and for the high- and low-quality blastocysts. The optimal cut-off value for the percentage of LNV sperm that maximised proper blastocyst formation was ≤24.5 %, and the cut-off value that maximised blastocyst quality was ≤19.5 %.ConclusionsThese results suggest a very early onset of paternal influences on embryo development. The evaluation of the incidence of vacuoles by MSOME may significantly improve upon the prognostic information provided by conventional semen analyses.