Occurrence of severe dengue in Rio de Janeiro: an ecological study

Introduction This study aimed to analyze the relationship between the incidence of severe dengue during the 2008 epidemic in Rio de Janeiro, Brazil, and socioeconomic indicators, as well as indicators of health service availability and previous circulation of the dengue virus serotype-3 (DENV-3). Methods In this ecological study, the units of analysis were the districts of Rio de Janeiro. The data were incorporated into generalized linear models, and the incidence of severe dengue in each district was the outcome variable. Results The districts with more cases of dengue fever in the 2001 epidemic and a higher percentage of residents who declared their skin color or race as black had higher incidence rates of severe dengue in the 2008 epidemic [incidence rate ratio (IRR)= 1.21; 95% confidence interval (95%CI)= 1.05-1.40 and IRR= 1.34; 95%CI= 1.16-1.54, respectively]. In contrast, the districts with Family Health Strategy (FHS) clinics were more likely to have lower incidence rates of severe dengue in the 2008 epidemic (IRR= 0.81; 95%CI= 0.70-0.93). Conclusions At the ecological level, our findings suggest the persistence of health inequalities in this region of Brazil that are possibly due to greater social vulnerability among the self-declared black population. Additionally, the protective effect of FHS clinics may be due to the ease of access to other levels of care in the health system or to a reduced vulnerability to dengue transmission that is afforded by local practices to promote health.

Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling

Forest regrowth occupies an extensive and increasing area in the Amazon basin, but accurate assessment of the impact of regrowth on carbon and nutrient cycles has been hampered by a paucity of available allometric equations. We develop pooled and species-specific equations for total aboveground biomass for a study site in the eastern Amazon that had been abandoned for 15 years. Field work was conducted using randomized branch sampling, a rapid technique that has seen little use in tropical forests. High consistency of sample paths in randomized branch sampling, as measured by the standard error of individual paths (14%), suggests the method may provide substantial efficiencies when compared to traditional procedures. The best fitting equations in this study used the traditional form Y=a×DBHb, where Y is biomass, DBH is diameter at breast height, and a and b are both species-specific parameters. Species-specific equations of the form Y=a(BA×H), where Y is biomass, BA is tree basal area, H is tree height, and a is a species-specific parameter, fit almost as well. Comparison with previously published equations indicated errors from -33% to +29% would have occurred using off-site relationships. We also present equations for stemwood, twigs, and foliage as biomass components.

Arrhythmogenic cardiomyopathy of the right ventricle. Predictive value of QT interval dispersion to assess arrhythmogenic risk and sudden death

OBJECTIVE: To determine in arrhythmogenic right ventricular cardiomyopathy the value of QT interval dispersion for identifying the induction of sustained ventricular tachycardia in the electrophysiological study or the risk of sudden cardiac death. METHODS: We assessed QT interval dispersion in the 12-lead electrocardiogram of 26 patients with arrhythmogenic right ventricular cardiomyopathy. We analyzed its association with sustained ventricular tachycardia and sudden cardiac death, and in 16 controls similar in age and sex. RESULTS: (mean ± SD). QT interval dispersion: patients = 53.8±14.1ms; control group = 35.0±10.6ms, p=0.001. Patients with induction of ventricular tachycardia: 52.5±13.8ms; without induction of ventricular tachycardia: 57.5±12.8ms, p=0.420. In a mean follow-up period of 41±11 months, five sudden cardiac deaths occurred. QT interval dispersion in this group was 62.0±17.8, and in the others it was 51.9±12.8ms, p=0.852. Using a cutoff > or = 60ms to define an increase in the degree of the QT interval dispersion, we were able to identify patients at risk of sudden cardiac death with a sensitivity of 60%, a specificity of 57%, and positive and negative predictive values of 25% and 85%, respectively. CONCLUSION: Patients with arrhythmogenic right ventricular cardiomyopathy have a significant increase in the degree of QT interval dispersion when compared with the healthy population. However it, did not identify patients with induction of ventricular tachycardia in the electrophysiological study, showing a very low predictive value for defining the risk of sudden cardiac death in the population studied.

Reduction of QTc interval dispersion. Potential mechanism of cardiac protection of pyridostigmine bromide

OBJECTIVE: Parasympathetic dysfunction is an independent risk factor in individuals with coronary artery disease, and cholinergic stimulation is a potential therapeutical option. We determined the effects of pyridostigmine bromide, a reversible anticholinesterase agent, on electrocardiographic variables of healthy individuals. METHODS: We carried out a cross-sectional, double blind, randomized, placebo-controlled study. We obtained electrocardiographic tracings in 12 simultaneous leads of 10 healthy young individuals at rest before and after oral administration of 45 mg of pyridostigmine or placebo. RESULTS: Pyridostigmine increased RR intervals (before: 886±27 ms vs after: 1054±37 ms) and decreased QTc dispersion (before: 72±9ms vs after: 45±3ms), without changing other electrocardiographic variables (PR segment, QT interval, QTc, and QT dispersion). CONCLUSION: Bradycardia and the reduction in QTc dispersion induced by pyridostigmine may effectively represent a protective mechanism if these results can be reproduced in individuals with cardiovascular diseases.

Establishing the prevalence of hypertension. Influence of sampling criteria

OBJECTIVE: To compare the prevalence of systemic hypertension in two different populations: a representative sample of the adult urban population of Porto Alegre, and individuals who sought blood pressure measurement in a hypertension prevention and control campaign. METHODS: A cross-sectional study was carried out involving a representative sample of the adult urban population of Porto Alegre and a population sample obtained from a hypertension prevention and control campaign, which included all the individuals who sought the blood pressure assessment unit at the Hospital das Clínicas in Porto Alegre. The following parameters were investigated: history of hypertension, use of antihypertensive drugs, age, and sex. Adjustments for age and sex in the prevalence rates were performed to make them comparable. RESULTS: Hypertension prevalence, defined as values > or = 160/95mmHg or treatment with antihypertensive drugs, was higher in the campaign sample (42%) as compared with the population sample (24%). Among those who were aware of their hypertensive condition and were under medication, 54% of the campaign sample and 62% of the representative population sample maintained their pressure levels <160/90mmHg. CONCLUSION: Prevalence rates of hypertension differed a lot in the campaign sample and in the representative population sample, showing that the sampling criterion may influence assessment of risk factors and bias the association between risk factors and health aggravations.

Relationship between Neutrophil-To-Lymphocyte Ratio and Electrocardiographic Ischemia Grade in STEMI

Background: Neutrophil-to-lymphocyte ratio (NLR) has been found to be a good predictor of future adverse cardiovascular outcomes in patients with ST-segment elevation myocardial infarction (STEMI). Changes in the QRS terminal portion have also been associated with adverse outcomes following STEMI. Objective: To investigate the relationship between ECG ischemia grade and NLR in patients presenting with STEMI, in order to determine additional conventional risk factors for early risk stratification. Methods: Patients with STEMI were investigated. The grade of ischemia was analyzed from the ECG performed on admission. White blood cells and subtypes were measured as part of the automated complete blood count (CBC) analysis. Patients were classified into two groups according to the ischemia grade presented on the admission ECG, as grade 2 ischemia (G2I) and grade 3 ischemia (G3I). Results: Patients with G3I had significantly lower mean left ventricular ejection fraction than those in G2I (44.58 ± 7.23 vs. 48.44 ± 7.61, p = 0.001). As expected, in-hospital mortality rate increased proportionally with the increase in ischemia grade (p = 0.036). There were significant differences in percentage of lymphocytes (p = 0.010) and percentage of neutrophils (p = 0.004), and therefore, NLR was significantly different between G2I and G3I patients (p < 0.001). Multivariate logistic regression analysis revealed that only NLR was the independent variable with a significant effect on ECG ischemia grade (odds ratio = 1.254, 95% confidence interval 1.120–1.403, p < 0.001). Conclusion: We found an association between G3I and elevated NLR in patients with STEMI. We believe that such an association might provide an additional prognostic value for risk stratification in patients with STEMI when combined with standardized risk scores.

Hypotensive Response Magnitude and Duration in Hypertensives: Continuous and Interval Exercise

Background: Although exercise training is known to promote post-exercise hypotension, there is currently no consistent argument about the effects of manipulating its various components (intensity, duration, rest periods, types of exercise, training methods) on the magnitude and duration of hypotensive response. Objective: To compare the effect of continuous and interval exercises on hypotensive response magnitude and duration in hypertensive patients by using ambulatory blood pressure monitoring (ABPM). Methods: The sample consisted of 20 elderly hypertensives. Each participant underwent three ABPM sessions: one control ABPM, without exercise; one ABPM after continuous exercise; and one ABPM after interval exercise. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR) and double product (DP) were monitored to check post-exercise hypotension and for comparison between each ABPM. Results: ABPM after continuous exercise and after interval exercise showed post-exercise hypotension and a significant reduction (p < 0.05) in SBP, DBP, MAP and DP for 20 hours as compared with control ABPM. Comparing ABPM after continuous and ABPM after interval exercise, a significant reduction (p < 0.05) in SBP, DBP, MAP and DP was observed in the latter. Conclusion: Continuous and interval exercise trainings promote post-exercise hypotension with reduction in SBP, DBP, MAP and DP in the 20 hours following exercise. Interval exercise training causes greater post-exercise hypotension and lower cardiovascular overload as compared with continuous exercise.

Evaluation of Electrocardiographic T-peak to T-end Interval in Subjects with Increased Epicardial Fat Tissue Thickness

Abstract Background: The association between periatrial adiposity and atrial arrhythmias has been shown in previous studies. However, there are not enough available data on the association between epicardial fat tissue (EFT) thickness and parameters of ventricular repolarization. Thus, we aimed to evaluate the association of EFT thickness with indices of ventricular repolarization by using T-peak to T-end (Tp-e) interval and Tp-e/QT ratio. Methods: The present study included 50 patients whose EFT thickness ≥ 9 mm (group 1) and 40 control subjects with EFT thickness < 9 mm (group 2). Transthoracic echocardiographic examination was performed in all participants. QT parameters, Tp-e intervals and Tp-e/QT ratio were measured from the 12-lead electrocardiogram. Results: QTd (41.1 ± 2.5 vs 38.6 ± 3.2, p < 0.001) and corrected QTd (46.7 ± 4.7 vs 43.7 ± 4, p = 0.002) were significantly higher in group 1 when compared to group 2. The Tp-e interval (76.5 ± 6.3, 70.3 ± 6.8, p < 0.001), cTp-e interval (83.1 ± 4.3 vs. 76±4.9, p < 0.001), Tp-e/QT (0.20 ± 0.02 vs. 0.2 ± 0.02, p < 0.001) and Tp-e/QTc ratios (0.2 ± 0.01 vs. 0.18 ± 0.01, p < 0.001) were increased in group 1 in comparison to group 2. Significant positive correlations were found between EFT thickness and Tp-e interval (r = 0.548, p < 0.001), cTp-e interval (r = 0.259, p = 0.01), and Tp-e/QT (r = 0.662, p < 0.001) and Tp-e/QTc ratios (r = 0.560, p < 0.001). Conclusion: The present study shows that Tp-e and cTp-e interval, Tp-e/QT and Tp-e/QTc ratios were increased in subjects with increased EFT, which may suggest an increased risk of ventricular arrhythmia.

Comparative Histopathology of Biomphalaria glabrata, B. tenagophila and B. straminea with Variable Degrees of Resistance to Schistosoma mansoni Miracidia

A comparative histopathological study of three snails species - Biomphalaria glabrata, B. tenagophila and B. straminea - which had been infected with Schistosoma mansoni miracidia revealed similar qualitative features, consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. However, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different histopathological pictures were observed in different snail species. While B. glabrata exhibited frequent focal (granulomatous) proliferation of amebocytes in several organs, B. tenagophila and B. straminea only rarely showed such reactive changes, suggesting that the mechanism of resistance to miracidial infection probably follows different pathways in the snail species studied

Comparison between splenic and lymph node aspirations as sampling methods for the parasitological detection of Leishmania chagasi infection in dogs

The sensitivities of spleen and lymph node cultures for the diagnosis of canine visceral leishmaniasis were compared in 64 anti-Leishmania antibody positive dogs from an endemic area in Brazil. The sensitivity of spleen cultures for Leishmania detection was 97.9%; in lymph node cultures it was 25%. Positive spleen culture was more frequent (p = 0.048, Fisher's exact probability test) in symptomatic (28 out of 33 animals) than in asymptomatic animals (19 out of 31 animals). These results support the use of spleen instead of lymph node aspiration as the choice method for the parasitological diagnosis of the infection.

The sample processing time interval as an influential factor in flow cytometry analysis of lymphocyte subsets

The objective of this paper is to propose a protocol to analyze blood samples in yellow fever 17DD vaccinated which developed serious adverse events. We investigated whether or not the time between sample collection and sample processing could interfere in lymphocyte subset percentage, for it is often impossible to analyze blood samples immediately after collection due to transport delay from collection places to the flow cytometry facility. CD4+CD38+ T, CD8+CD38+ T, CD3+ T, CD19+ B lymphocyte subsets were analyzed by flow cytometry in nine healthy volunteers immediately after blood collection and after intervals of 24 and 48 h. The whole blood lysis method and gradient sedimentation by Histopaque were applied to isolate peripheral blood mononuclear cells for flow cytometry analyses. With the lysis method, there was no significant change in lymphocyte subset percentage between the two time intervals (24 and 48 h). In contrast, when blood samples were processed by Histopaque gradient sedimentation, time intervals for sample processing influenced the percentage in T lymphocyte subsets but not in B cells. From the results obtained, we could conclude that the whole blood lysis method is more appropriate than gradient sedimentation by Histopaque for immunophenotyping of blood samples collected after serious adverse events, due to less variation in the lymphocyte subset levels with respect to the time factor.

Case-control study of factors associated with chronic Chagas heart disease in patients over 50 years of age

A case-control study on chronic Chagas heart disease (CCHD) was carried out between 1997 and 2005. Ninety patients over 50 years of age were examined for factors related to (CCHD). Fourty-six patients (51.1%) with Chagas heart disease (anomalous ECG) were assigned to the case group and 44 (48.9%) were included in the control group as carriers of undetermined forms of chronic disease. Social, demographic (age, gender, skin color, area of origin), epidemiological (permanence within an endemic zone, family history of Chagas heart disease or sudden death, physical strain, alcoholism, and smoking), and clinical (systemic hypertension) variables were analyzed. The data set was assessed through single-variable and multivariate analysis. The two factors independently associated with heart disease were age - presence of heart disease being three times higher in patients over 60 years of age (odds ratio, OR: 2.89; confidence interval of 95%: 1.09-7.61) - and family history of Chagas heart disease (OR: 2.833, CI 95%: 1.11-7.23). Systemic hypertension and gender did not prove to hold any association with heart disease, as neither did skin color, but this variable showed low statistical power due to reduced sample size.

Leprosy reactions: the effect of gender and household contacts

Various host-related factors have been reported as relevant risk factors for leprosy reactions. To support a new hypothesis that an antigenic load in local tissues that is sufficient to trigger the immune response may come from an external supply of Mycobacterium leprae organisms, the prevalence of reactional leprosy was assessed against the number of household contacts. The number of contacts was ascertained at diagnosis in leprosy patients coming from an endemic area of Brazil. The prevalence of reactions (patients with reactions/total patients) was fitted by binomial regression and the risk difference (RD) was estimated with a semi-robust estimation of variance as a measure of effect. Five regression models were fitted. Model 1 included only the main exposure variable "number of household contacts"; model 2 included all four explanatory variables ("contacts", "fertile age", "number of skin lesions" and "bacillary index") that were found to be associated with the outcome upon univariate analysis; models 3-5 contained various combinations of three predictors. Male and female patients were analyzed separately. In females, household contacts were a significant predictor for leprosy reactions in model 1 [crude RD = 0.06; 95% confidence interval (CI) = 0.01; 0.12] and model 5 (RD = 0.05; CI = 0.02; 0.09), which included contacts, bacillary index and skin lesions as predictors. Other models were unsatisfactory because the joint presence of fertile age and bacillary index was a likely source of multicollinearity. No significant results were obtained for males. The likely interpretation of our findings might suggest that in female patients, leprosy reactions may be triggered by an external spreading of M. leprae by healthy carrier family members. The small number of observations is an obvious limitation of our study which requires larger confirmatory studies.