Random regression models to estimate genetic parameters for milk production of Guzerat cows using orthogonal Legendre polynomials

The objective of this work was to compare random regression models for the estimation of genetic parameters for Guzerat milk production, using orthogonal Legendre polynomials. Records (20,524) of test-day milk yield (TDMY) from 2,816 first-lactation Guzerat cows were used. TDMY grouped into 10-monthly classes were analyzed for additive genetic effect and for environmental and residual permanent effects (random effects), whereas the contemporary group, calving age (linear and quadratic effects) and mean lactation curve were analized as fixed effects. Trajectories for the additive genetic and permanent environmental effects were modeled by means of a covariance function employing orthogonal Legendre polynomials ranging from the second to the fifth order. Residual variances were considered in one, four, six, or ten variance classes. The best model had six residual variance classes. The heritability estimates for the TDMY records varied from 0.19 to 0.32. The random regression model that used a second-order Legendre polynomial for the additive genetic effect, and a fifth-order polynomial for the permanent environmental effect is adequate for comparison by the main employed criteria. The model with a second-order Legendre polynomial for the additive genetic effect, and that with a fourth-order for the permanent environmental effect could also be employed in these analyses.

Food consumption of adolescents. A simplified questionnaire for evaluating cardiovascular risk

OBJECTIVE: To develop a simplified questionnaire for self-evaluation by adolescents of foods associated with the risk of coronary diseases. METHODS: Frequency questionnaires about 80 foods were answered by representative samples of 256 adolescents aged 12 to 19 from Rio de Janeiro as part of the Nutrition and Health Research project. The dependent variable was the serum cholesterol predicting equation as influenced by diet, and the independent variables were the foods. The variables were normalized and, using Pearson's correlation coefficient, those with r>0.10 were selected for the regression model. The model was analyzed for sex, age, random sample, and total calories. Those food products that explained 85% of the cholesterol variation equation were present in the caloric model, and contained trans fatty acids were selected for the questionnaire. RESULTS: Sixty-five food products had a statistically significant correlation (P<0.001) with the dependent variable. The simplified questionnaire included 9 food products present in all tested models: steak or broiled meat, hamburger, full-fat cheese, French fries or potato chips, whole milk, pies or cakes, cookies, sausages, butter or margarine. The limit of the added food points for self-evaluation was 100, and over 120 points was considered excessive. CONCLUSION: The scores given to the food products and the criteria for the evaluation of the consumption limits enabled the adolescents to get to know and to balance their intake.

The use of ALOS/PALSAR data for estimating sugarcane productivity

Some models have been developed using agrometeorological and remote sensing data to estimate agriculture production. However, it is expected that the use of SAR images can improve their performance. The main objective of this study was to estimate the sugarcane production using a multiple linear regression model which considers agronomic data and ALOS/PALSAR images obtained from 2007/08, 2008/09 and 2009/10 cropping seasons. The performance of models was evaluated by coefficient of determination, t-test, Willmott agreement index (d), random error and standard error. The model was able to explain 79%, 12% and 74% of the variation in the observed productions of the 2007/08, 2008/09 and 2009/10 cropping seasons, respectively. Performance of the model for the 2008/09 cropping season was poor because of the occurrence of a long period of drought in that season. When the three seasons were considered all together, the model explained 66% of the variation. Results showed that SAR-based yield prediction models can contribute and assist sugar mill technicians to improve such estimates.

Social contextual factors contributing to child and adolescent labor: an ecological analysis

OBJECTIVE: To examine the relationship between social contextual factors and child and adolescent labor. METHODS: Population-based cohort study carried out with 2,512 families living in 23 subareas of a large urban city in Brazil from 2000 to 2002. A random one-stage cluster sampling was used to select families. Data were obtained through individual household interviews using questionnaires. The annual cumulative incidence of child and adolescent labor was estimated for each district. New child and adolescent labor cases were those who had their first job over the two-year follow-up. The annual cumulative incidence of child and adolescent labor was the response variable and predictors were contextual factors such as lack of social support, social deprivation, unstructured family, perceived violence, poor school quality, poor environment conditions, and poor public services. Pearson's correlation and multiple linear regression were used to assess the associations. RESULTS: There were selected 943 families corresponding to 1,326 non-working children and adolescents aged 8 to 17 years. Lack of social support, social deprivation, perceived violence were all positively and individually associated with the annual cumulative incidence of child and adolescent labor. In the multiple linear regression model, however, only lack of social support and perceived violence in the neighborhood were positively associated to child and adolescent labor. No effect was found for poor school quality, poor environment conditions, poor public services or unstructured family. CONCLUSIONS: Poverty reduction programs can reduce the contextual factors associated with child and adolescent labor. Violence reduction programs and strengthening social support at the community level may contribute to reduce CAL.

Prevalence and factors associated with HCV infection among elderly individuals in a southern Brazilian city

Introduction Few Latin American studies have assessed the prevalence of hepatitis C virus (HCV) infection in elderly individuals, in whom the highest rates are expected. We aimed to investigate the prevalence of and factors associated with HCV infection in elderly residents in the municipality of Tubarão, Santa Catarina. Methods This cross-sectional study included 820 individuals (aged ≥ 60 years) who were selected by simple random sampling. The presence of anti-HCV antibodies was tested by chemiluminescence, and HCV RNA detection was performed for the anti-HCV-reactive subjects. Those individuals who were anti-HCV reactive but had undetectable HCV RNA levels were tested using a third-generation recombinant immunoblot assay. The variables were compared using the chi-squared test or Fisher's exact test, and those variables with p < 0.05 were included in the logistic regression model. Results The mean patient age was 68.6 years (SD 7.0 years); 39% were men, and 92% were Caucasian. Eighteen subjects were anti-HCV positive. Among these individuals, 4 were characterized as false-positives, leaving 14 (1.7%) individuals with confirmed infections for analysis. HCV infection was associated with an age older than 65 years, households with 3 or more residents and the previous transfusion of blood products. In the logistic regression analysis, the following variables were independently associated with HCV infection: households with 3 or more residents (OR 7.9, 95% CI 1.7–35.9, p = 0.008) and previous blood transfusion (OR 6.2, 95% CI 2.1–18.6, p = 0.001). Conclusions The HCV prevalence in the elderly population in the municipality of Tubarão was higher than that found in previous studies of blood donors in the same region. Although exposure to contaminated blood products remained important, other transmission routes, such as household transmission, could play a role in HCV infection.

Hyperhomocyst(e)inemia in chronic stable renal transplant patients

PURPOSE: Hyperhomocyst(e)inaemia is an important risk factor for atherosclerosis, which is currently a major cause of death in renal transplant patients. The aim of this study was to assess the influence of immunosuppressive therapy on homocyst(e)inemia in renal transplant recipients. METHODS: Total serum homocysteine (by high performance liquid chromatography), creatinine, lipid profile, folic acid (by radioimmunoassay-RIA) and vitamin B12 (by RIA) concentrations were measured in 3 groups. Group I patients (n=20) were under treatment with cyclosporine, azathioprine, and prednisone; group II (n=9) were under treatment with azathioprine and prednisone; and group III (n=7) were composed of renal graft donors for groups I and II. Creatinine, estimated creatinine clearance, cyclosporine trough level, lipid profile, folic acid, and vitamin B12 concentrations and clinical characteristics of patients were assessed with the aim of ascertaining determinants of hyperhomocyst(e)inemia. RESULTS: Patient ages were 48.8 ± 15.1 yr (group I), 43.3 ± 11.3 yr (group II); and 46.5 ± 14.8 yr (group III). Mean serum homocyst(e)ine (tHcy) concentrations were 18.07 ± 8.29 mmol/l in renal transplant recipients; 16.55 ± 5.6 mmol/l and 21.44 ± 12.1 mmol/l respectively for group I (with cyclosporine) and group II (without cyclosporine) (NS). In renal donors, tHcy was significantly lower (9.07 ± 3.06 mmol/l; group I + group II vs. group III, p<0.008). There was an unadjusted correlation (p<0.10) between age (r=0.427; p<0.005) body weight (r=0.412; p<0.05), serum creatinine (r=0.427; p<0.05), estimated creatinine clearance (r=0.316; p<0.10), and tHcy in renal recipients (group I +II). Independent regressors (r²=0.46) identified in the multiple regression model were age (coefficient= 0.253; p=0.009) and serum creatinine (coefficient=8.07; p=0.045). We found no cases of hyperhomocyst(e)inemia in the control group. In contrast, 38% of renal recipients had hyperhomocyst(e)inemia: 7 cases (35%) on cyclosporine and 4 (45%) without cyclosporine, based on serum normal levels. CONCLUSIONS: Renal transplant recipients frequently have hyperhomocyst(e)inemia. Hyperhomocyst(e)inemia in renal transplant patients is independent of the scheme of immunosuppression they are taking. The older the patients are and the higher are their serum creatinine levels, the more susceptible they are to hyperhomocyst(e)inemia following renal transplantation.

Association between LDL-C, Non HDL-C, and Apolipoprotein B Levels with Coronary Plaque Regression

Background:Previous reports have inferred a linear relationship between LDL-C and changes in coronary plaque volume (CPV) measured by intravascular ultrasound. However, these publications included a small number of studies and did not explore other lipid markers.Objective:To assess the association between changes in lipid markers and regression of CPV using published data.Methods:We collected data from the control, placebo and intervention arms in studies that compared the effect of lipidlowering treatments on CPV, and from the placebo and control arms in studies that tested drugs that did not affect lipids. Baseline and final measurements of plaque volume, expressed in mm3, were extracted and the percentage changes after the interventions were calculated. Performing three linear regression analyses, we assessed the relationship between percentage and absolute changes in lipid markers and percentage variations in CPV.Results:Twenty-seven studies were selected. Correlations between percentage changes in LDL-C, non-HDL-C, and apolipoprotein B (ApoB) and percentage changes in CPV were moderate (r = 0.48, r = 0.47, and r = 0.44, respectively). Correlations between absolute differences in LDL-C, non‑HDL-C, and ApoB with percentage differences in CPV were stronger (r = 0.57, r = 0.52, and r = 0.79). The linear regression model showed a statistically significant association between a reduction in lipid markers and regression of plaque volume.Conclusion:A significant association between changes in different atherogenic particles and regression of CPV was observed. The absolute reduction in ApoB showed the strongest correlation with coronary plaque regression.

Left Atrial Volume Determinants in Patients with Non-Ischemic Dilated Cardiomyopathy

Background:Left atrial volume (LAV) is a predictor of prognosis in patients with heart failure.Objective:We aimed to evaluate the determinants of LAV in patients with dilated cardiomyopathy (DCM).Methods:Ninety patients with DCM and left ventricular (LV) ejection fraction ≤ 0.50 were included. LAV was measured with real-time three-dimensional echocardiography (eco3D). The variables evaluated were heart rate, systolic blood pressure, LV end-diastolic volume and end-systolic volume and ejection fraction (eco3D), mitral inflow E wave, tissue Doppler e´ wave, E/e´ ratio, intraventricular dyssynchrony, 3D dyssynchrony index and mitral regurgitation vena contracta. Pearson´s coefficient was used to identify the correlation of the LAV with the assessed variables. A multiple linear regression model was developed that included LAV as the dependent variable and the variables correlated with it as the predictive variables.Results:Mean age was 52 ± 11 years-old, LV ejection fraction: 31.5 ± 8.0% (16-50%) and LAV: 39.2±15.7 ml/m2. The variables that correlated with the LAV were LV end-diastolic volume (r = 0.38; p < 0.01), LV end-systolic volume (r = 0.43; p < 0.001), LV ejection fraction (r = -0.36; p < 0.01), E wave (r = 0.50; p < 0.01), E/e´ ratio (r = 0.51; p < 0.01) and mitral regurgitation (r = 0.53; p < 0.01). A multivariate analysis identified the E/e´ ratio (p = 0.02) and mitral regurgitation (p = 0.02) as the only independent variables associated with LAV increase.Conclusion:The LAV is independently determined by LV filling pressures (E/e´ ratio) and mitral regurgitation in DCM.

Analysis and estimative of schistosomiasis prevalence for the state of Minas Gerais, Brazil, using multiple regression with social and environmental spatial data

The aim of this work is to establish a relationship between schistosomiasis prevalence and social-environmental variables, in the state of Minas Gerais, Brazil, through multiple linear regression. The final regression model was established, after a variables selection phase, with a set of spatial variables which contains the summer minimum temperature, human development index, and vegetation type variables. Based on this model, a schistosomiasis risk map was built for Minas Gerais.

Impacts of deforestation on water balance components of a watershed on the Brazilian East Coast

The Brazilian East coast was intensely affected by deforestation, which drastically cut back the original biome. The possible impacts of this process on water resources are still unknown. The purpose of this study was an evaluation of the impacts of deforestation on the main water balance components of the Galo creek watershed, in the State of Espírito Santo, on the East coast of Brazil. Considering the real conditions of the watershed, the SWAT model was calibrated with data from 1997 to 2000 and validated for the period between 2001 and 2003. The calibration and validation processes were evaluated by the Nash-Sutcliffe efficiency coefficient and by the statistical parameters (determination coefficient, slope coefficient and F test) of the regression model adjusted for estimated and measured flow data. After calibration and validation of the model, new simulations were carried out for three different land use scenarios: a scenario in compliance with the law (C1), assuming the preservation of PPAs (permanent preservation areas); an optimistic scenario (C2), which considers the watershed to be almost entirely covered by native vegetation; and a pessimistic scenario (C3), in which the watershed would be almost entirely covered by pasture. The scenarios C1, C2 and C3 represent a soil cover of native forest of 76, 97 and 0 %, respectively. The results were compared with the simulation, considering the real scenario (C0) with 54 % forest cover. The Nash-Sutcliffe coefficients were 0.65 and 0.70 for calibration and validation, respectively, indicating satisfactory results in the flow simulation. A mean reduction of 10 % of the native forest cover would cause a mean annual increase of approximately 11.5 mm in total runoff at the watershed outlet. Reforestation would ensure minimum flows in the dry period and regulate the maximum flow of the main watercourse of the watershed.

Estudo do coeficiente de partição octanol-água de bifenilas policloradas (PCBs) utilizando parâmetros topológicos

A model based on chemical structure was developed for the accurate prediction of octanol/water partition coefficient (K OW) of polychlorinated biphenyls (PCBs), which are molecules of environmental interest. Partial least squares (PLS) was used to build the regression model. Topological indices were used as molecular descriptors. Variable selection was performed by Hierarchical Cluster Analysis (HCA). In the modeling process, the experimental K OW measured for 30 PCBs by thin-layer chromatography - retention time (TLC-RT) has been used. The developed model (Q² = 0,990 and r² = 0,994) was used to estimate the log K OW values for the 179 PCB congeners whose K OW data have not yet been measured by TLC-RT method. The results showed that topological indices can be very useful to predict the K OW.

Multiple centroid method to evaluate the adaptability of alfalfa genotypes

This study aimed to evaluate the efficiency of multiple centroids to study the adaptability of alfalfa genotypes (Medicago sativa L.). In this method, the genotypes are compared with ideotypes defined by the bissegmented regression model, according to the researcher's interest. Thus, genotype classification is carried out as determined by the objective of the researcher and the proposed recommendation strategy. Despite the great potential of the method, it needs to be evaluated under the biological context (with real data). In this context, we used data on the evaluation of dry matter production of 92 alfalfa cultivars, with 20 cuttings, from an experiment in randomized blocks with two repetitions carried out from November 2004 to June 2006. The multiple centroid method proved efficient for classifying alfalfa genotypes. Moreover, it showed no unambiguous indications and provided that ideotypes were defined according to the researcher's interest, facilitating data interpretation.

Factors associated with infant feeding practices after hospital discharge

OBJECTIVE: To assess factors associated with infant feeding practices on the first day at home after hospital discharge. METHODS: A total of 209 women, who had a child aged four months or less and were living in Itapira, Brazil, were interviewed during the National Immunization Campaign Day in 1999. Statistical analysis was performed using the Chi-square test and a logistic regression model was used for verifying an association between dependent and independent variables. RESULTS: Women aged 25.5 years on average and 18.2% were teenagers. Fifty-three percent of the women delivered vaginally and most vaginal deliveries (78.5%) took place in the public hospital. The prevalence of exclusive breastfeeding on the first day at home was 78.1% and 11.6% of the infants were receiving formula at this time. The only factor associated with EBF on the first day at home was being a teenaged-primiparous mother (OR=9.40; 95% CI: 1.24-71.27). This association remained statistically significant even after controlling for type of delivery and hospital where the birth took place. Feeding formula on the first day at home was only significantly associated with the hospital (i.e., birth at the city hospital was a protective factor (OR=0.33; 95% CI: 0.13-0.86), even after controlling for vaginal delivery. CONCLUSIONS: On the first day at home after hospital discharge, teenaged-primiparous mothers were more likely to exclusive breastfeeding as well as those infants born in the municipal public hospital. Further studies are needed from a multidisciplinary approach.

Living conditions and receptive vocabulary of children aged two to five years

OBJECTIVE: To assess the receptive vocabulary of children aged between two years and six months and five years and eleven months who were attending childcare centers and kindergarten schools. METHODS: An analytical cross-sectional study was carried out in the municipality of Embu, Southeastern Brazil. The Peabody Picture Vocabulary Test and analysis of factors associated with children's performance were applied. The sample consisted of 201 children of both genders, aged between two and six years. Statistical analysis was performed using multivariate analysis and logistic regression model. The dependent variable analyzed was test performance and the independent variables were child's age, mother's level of education and family socio-demographic characteristics. RESULTS: It was observed that 44.3% of the children had performances in the test that were below what would be expected for their age. The factors associated with the best performances in the test were child's age (OR=2.4; 95% CI: 1.6-3.5) and mother's education level (OR= 3.2; 95% CI: 1.3-7.4). CONCLUSIONS: Mother's education level is important for child's language development. Settings such as childcare and kindergarten schools are protective factors for child development in families of low income and education.

Central obesity and dietary intake in HIV/AIDS patients

OBJECTIVE: To assess the association between dietary intake and central obesity among people living with HIV/AIDS and receiving highly active antiretroviral therapy. METHODS: A cross-sectional study was conducted involving 223 adult individuals in the city of São Paulo city in 2002. The study population was classified according to central obesity, defined as waist-to-hip ratio >0.95 for men and >0.85 for women. The dietary variables studied were energy consumption (in calories and calories/kilo of body weight), macronutrients (in grams and % of energy intake), total fiber (grams) and fruit and vegetables intake (grams). The potential confounders examined were sex, skin color, age, schooling, income, body mass index, physical activity, smoking habits, peripheral CD4+ T lymphocyte count and length of protease inhibitor use. The multiple logistic regression model was performed in order to evaluate the association between central obesity and dietary intake. RESULTS: The prevalence of central obesity was 45.7% and it was associated with greater consumption of lipids: for every increase of 10g of lipid intake the odds of central obesity increased 1.28 times. Carbohydrate consumption showed negative association (OR=0.93) with central obesity after adjustment for control variables. CONCLUSIONS: The results suggest that the amount of carbohydrates and lipids in the diet, regardless of total energy intake, may modify the chance of developing central obesity in the studied population. Nutritional interventions may be beneficial for preventing central obesity among HIV/AIDS patients.