Neuron count reevaluation in the myenteric plexus of chagasic megacolon after morphometric neuron analysis.

This study was made with the objective of reevaluating the colon denervation in chronic Chagas' disease. The diameters of neuron perikaryons of the myenteric plexus were measured on paraffin sections in a ring from the sigmoid in Chagas' disease patients, 17 with and 10 without megacolon and in 10 non-chagasic controls. All neurons were counted in ten en-echelon sections. Neuron hypertrophy only occurred in the group with megacolon, and the average increase in diameter was 69.3%. This could generate an error factor in the neuron count by increasing the probability of neurons being seen in a greater number of histological sections. The original result of the neuron count gave medians of 1264, 1961, and 2665 in the groups of chagasic patients with megacolon, without megacolon, and in the control, respectively. The denervation was greater than 55% in only seven megacolon cases (41.2%). After applying a correction factor, the median in the group with megacolon was 746, and the denervation was greater than 55% in 13 cases (76.5%). This occurrence demonstrates the need to apply a correction factor when the neuron count in chagasic megacolon is being evaluated and in the other pathologies where neuron hypertrophy may be found.

Risk factors for the increasing trend in low birth weight among live births born by vaginal delivery, Brazil.

OBJECTIVE: To identify risk factors for low birth weight (LBW) among live births by vaginal delivery and to determine if the disappearance of the association between LBW and socioeconomic factors was due to confounding by cesarean section. METHODS: Data were obtained from two population-based cohorts of singleton live births in Ribeirão Preto, Southeastern Brazil. The first one comprised 4,698 newborns from June 1978 to May 1979 and the second included 1,399 infants born from May to August 1994. The risks for LBW were tested in a logistic model, including the interaction of the year of survey and all independent variables under analysis. RESULTS: The incidence of LBW among vaginal deliveries increased from 7.8% in 1978--79 to 10% in 1994. The risk was higher for: female or preterm infants; newborns of non-cohabiting mothers; newborns whose mothers had fewer prenatal visits or few years of education; first-born infants; and those who had smoking mothers. The interaction of the year of survey with gestational age indicated that the risk of LBW among preterm infants fell from 17.75 to 8.71 in 15 years. The mean birth weight decreased more significantly among newborns from qualified families, who also had the highest increase in preterm birth and non-cohabitation. CONCLUSIONS: LBW among vaginal deliveries increased mainly due to a rise in the proportion of preterm births and non-cohabiting mothers. The association between cesarean section and LBW tended to cover up socioeconomic differences in the likelihood of LBW. When vaginal deliveries were analyzed independently, these socioeconomic differences come up again.

[Pediatric care and associated factors in São Luís (Maranhão) Brasil]. / Cobertura de puericultura e fatores associados em São Luís (Maranhão), Brasil.

Pediatric care is fundamental to preventing several diseases during the early years of childhood. Early medical care and having at least nine checkups in the first year of life are the ideal in pediatric care. It is essential to periodically assess whether or not these goals are being met. In 1994, a cross-sectional study was carried out using three-stage cluster sampling to measure coverage of pediatric care and factors associated with that care among children in the city of São Luís, in the state of Maranhão, Brazil. For data collection, a standardized questionnaire was used with the mother of the child or another person responsible for the child. The percentage of those refusing to participate or who were absent was 7%. This work analyzes data concerning 290 children between 1 and 23 months of age. The coverage estimates and 95% confidence intervals took into consideration possible effects of the study design. Cox's regression, modified for cross-sectional studies, was used to estimate adjusted relative risks. Pediatric care coverage for the population studied was 80%. The children had an average of 7.8 checkups in the first year; 44% of the children had six or fewer checkups during the first year of life, well below the recommended number. Eighty-one percent of the children were seen in the Brazilian public health care system (Sistema Unico de Saúde, SUS), and only 15% used health insurance. After adjusting for confounding factors, the factors "greater number of siblings at home" and "father with four or fewer years of schooling" were associated with not having checkups. After adjustment, family income was not associated with the number of checkups. Encouraging educational activities and perhaps also family planning programs are important strategies for increasing the coverage of pediatric care in the city of São Luís.

Risk factors for the increasing caesarean section rate in Southeast Brazil: a comparison of two birth cohorts, 1978-1979 and 1994.

BACKGROUND: Brazil has the highest caesarean section (CS) rate in the world (36.4% in 1996). METHODS: Risk factors for increasing CS rate were studied in two population-based cohorts of singleton live births in families residing in the municipality of Ribeirao Preto, State of Saõ Paulo, Southeast Brazil. The first comprised births from June 1978 to May 1979 (6750 births-one-year survey) and the second births from May to August 1994 (2846 births-4-month survey). Multiple unconditional logistic regression modelling was used to control for confounding. RESULTS: The CS rate rose from 30.3% in 1978-1979 to 50.8% in 1994. In 1978-1979, socioeconomic, reproductive and demographic variables, and health service factors were associated with CS rate. In 1994, only reproductive, demographic and health service factors remained associated, e.g. hour of delivery (from 7 a.m. to 12 p.m.), attendance by the same physician for prenatal care and delivery, > or =4 prenatal visits, maternal age > or =30 years, 1-3 previous live births and birthweight 3500-3999 g. CONCLUSION: Caesarean section in Brazil is widely performed for non-medical reasons in which physician convenience plays an important role. There is an urgent need for public health interventions to reduce the CS rate in Brazil, mainly directed towards cultural beliefs and physician behaviour.

[Vaccination coverage and risk factors associated to non-vaccination in a urban area of northeastern Brazil, 1994]. / Cobertura vacinal e fatores de risco associados à não-vacinação em localidade urbana do nordeste brasileiro, 1994.

INTRODUCTION: The assessment of vaccination coverage and risk factors for non-vaccination is important to evaluate vaccination programs and to identify children not properly vaccinated. METHODS: A cross-sectional household survey was carried out in the municipality of S. Luís, Maranhão, Brazil by means of a standardized questionnaire. Multistage cluster sampling was used to identify children of 12-59 months of age residing in the city in 1994. The mother or other person responsible for the children was interviewed. Fifty census clusters were visited and 40 households were sampled in each. On average, 15 children were found in each cluster. Design effect was calculated for each estimate. Health service utilization was analyzed according to socioeconomic and demographic indicators, and perceived morbidity using proportional hazard modeling (Cox's regression). RESULTS: Vaccination coverage levels were 72.4% for BCG, 59.9% for three doses of polio vaccine, 57% for three doses of DTP vaccine and 54.7% for measles vaccine. Vaccination levels have remained statistically unchanged over the last three years. Lower maternal schooling continues to be associated with increased risk of non-vaccination in the multivariable analysis. CONCLUSION: Vaccination levels were low. Health education activities are one of the suggested strategies to increase vaccination coverage.

[Risk factors for hospitalization of children aged 1 to 4 years in Sao Luis, Maranhao, Brazil]. / Fatores de risco para hospitalização de crianças de um a quatro anos em São Luís, Maranhão, Brasil.

Risk factors for pediatric hospitalization were studied using a cross-sectional multi-stage cluster sample survey. A standardized questionnaire was answered by children's mothers or other care providers. In the municipality of São Luís, Maranhão, Brazil, 596 children aged 1 to 4 years were sampled in 50 census tracts. Design effect was calculated for each estimate. Hospitalization rate was 24. 4%. Main causes of hospitalization were pneumonia (7.3%) and diarrhea (7.1%). The Unified National Health System (SUS) and private insurance accounted for 78.1% and 18.2% of hospital admissions, respectively. After adjustment for confounding by Cox proportional hazards model modified for cross-sectional design, children whose families earned less than one minimum monthly wage and those with private insurance were at higher risk of hospitalization. Hospitalization due to outpatient-sensitive diseases accounted for most cases. The U-shaped hospitalization pattern suggests low quality of outpatient services among the poor and may be a proxy indicator for unnecessary and iatrogenic hospitalization among privately insured children.

[Perinatal health: methodology and characteristics of the studied population]. / Saúde perinatal: metodologia e características da população estudada.

OBJECTIVE: To describe the methodological procedures and some sociodemographic and medical care characteristics of the population studied in a research project on perinatal health developed in the Ribeirão Preto county, SP, in 1994, in order to make historical comparisons with the indicators of mother-child health of a similar study conducted 15 years before in the same municipality. MATERIAL AND METHOD: All the hospital births that occurred in Ribeirão Preto from June 1978 to May 1979 were studied by interviewing the mothers and obtaining data about maternal and paternal habits, social situation of the family, medical care during pregnancy and delivery, duration of pregnancy, and anthropometric and mortality data about the newborn children. A new study was conducted in 1994 using the same methodology to collect data about a sample of 1/3 of the births that had occurred in the municipality in that year (all the hospital births observed during a period of 4 months), and also about the mortality of this group up to one year after the termination of birth data collection. The interviews were held after delivery and infant weight and length were measured immediately after birth. Infant mortality was evaluated by surveying the data referring to all deaths of infants born during the year of the study and up to 1 year after its termination. The data were obtained from the Municipal Health Secretariat to which copies of all death certificates emitted in the registry offices of the county are sent obligatorily. RESULTS: An investigation was made into 3,663 births, 3,579 of which were singletons; of these, 2,846 were from the municipality. Comparison with the data obtained in the previous study showed an increase in the frequency of some indicators such as adolescent mothers, prematurity, low birth weight and cesarian section; on the other hand, there was a 50% decrease in the mortality rate and its components.

Trends in low birth weight: a comparison of two birth cohorts separated by a 15-year interval in Ribeirão Preto, Brazil.

The incidence and some determinants of low birth weight (LBW) were studied in two population-based cohorts of singletons born live to families in Ribeirão Preto, São Paulo State, Brazil. The first cohort comprised infants born between June 1978 and May 1979 (6750 births--population survey) and the second, infants born between May and August 1994 (2990 births--sample survey). The incidence of LBW was 7.2% in 1978-79 and 10.6% in 1994. After adjustment for confounding factors, the following determinants remained significant in 1978-79: female sex, maternal age > or = 35 years, preterm delivery, < four antenatal health visits, maternal smoking, lower level of maternal education, and manual work/unemployment. In 1994, the significant determinants were preterm delivery, maternal smoking and caesarean section. The adjusted percentage population attributable risk (PAR%) fell for the majority of risk factors but increased for caesarean section, preterm birth, multiparity (> or = 5), primiparity and non-cohabitation. The increase in the rate of LBW from 1978-79 to 1994 was higher for families with more qualified occupations, and occurred only for infants delivered at 36-40 weeks' gestational age and weighing 1500-2499 g, i.e. those most likely to be born by elective caesarean section. The caesarean section rate rose from 30.3% in 1978-79 to 51.1% in 1994. The increase in LBW was probably due to iatrogenic practices associated with elective caesarean section.

Renal changes induced by envenomation with Africanized bee venom in female Wistar rats.

Human envenomation caused by bee or wasp stings has been reported to cause acute renal failure (ARF), usually due to acute tubular necrosis (ATN), as a frequent complication. The pathogenetic mechanisms of ATN occurring in these accidents are still unclear. In the present study, female Wistar rats weighing 150-200 g were injected intravenously with Africanized bee venom at a dose of 0.4 microl/100 g body weight and used in functional and light microscopy studies. The animals were divided into two groups: the early group was studied 3-8 h after inoculation, and the late group was studied 24-30 h thereafter. The animals showed ARF characterized by reduction of glomerular filtration rate with increasing levels of plasma creatinine. They also showed increased fractional sodium and potassium excretions, suggesting changes in the proximal portion of the nephron. The water transport through collecting tubules was reduced, with consequent diuresis, indicating functional changes in the distal portion of the nephron. These functional changes were more marked in the early group, with recovery tending to occur after 24 h. Albuminuria was also observed in this group. Light microscopy showed ATN mainly in cortex and outer medulla, with isolated necrosis in cells or small groups of cells and cast formation in the distal and collecting tubules. After 24 h frequent mitotic figures were found in the tubular epithelium. The observed ARF was due to ATN which in turn was probably caused by multiple effects, mainly hemodynamic changes secondary to cardiotoxicity and systemic vasodilation caused by the venom, myohemoglobinuria, and the direct action of the venom on tubular cells.

[Course of serologic positivity to Chagas disease in a rural community in Brazil]. / Evolução da positividade sorológica para a doença de Chagas numa comunidade rural brasileira.

In order to assess the evolution of seropositivity for Chagas' disease in the rural community of Cássia dos Coqueiros, in São Paulo state, we compared two cross-sectional studies performed at that site in 1971-1972 and in 1989-1991. In the first survey the complement fixation test was used to determine seropositivity for the disease. In this study, the total prevalence of Chagas' disease was found to be 16.6%, with values ranging from 2.9 to 61.9% (in the 10-19 and 50-59 year age groups, respectively). In the 1989-1991 study, in which indirect immunofluorescence was used, the total prevalence dropped to 10.1%, with a minimum of 0.4% (in the 10-19 year age group) and a maximum of 44.8% (in persons over 60 years of age). Among subjects born in Cássia dos Coqueiros, the 1989-1991 study showed seropositivity after age 38, with only one exception (a 24-year-old man). The drop in the seropositivity index for Chagas' disease in Cásia dos Coqueiros during the period under study can be partially attributed to socioeconomic factors, such as improved living conditions and the progressive abandonment of rural areas. Thus, our results point to the spraying of households with residual insecticides, which began in 1950, as the pivotal factor in the fight against triatomine bugs and in disease control. These results suggest that transmission may have been interrupted as early as the latter part of 1954 and later consolidated as a result of improved socioeconomic conditions and the elimination of Triatoma infestans from the study area.

Supraceliac clamping in the surgical treatment of abdominal aortic aneurysm. An experimental study in dogs.

Previous reports have suggested the use of supraceliac aortic clamping in the surgical treatment of abdominal aortic aneurysm of difficult approach. The objective of the present report was to study the hepatic and renal metabolic changes of three groups of dogs submitted to temporary clamping (30 minutes) of the abdominal aorta at three different levels: below the renal arteries, infrarenal group (8 dogs); above the renal arteries, suprarenal group (9 dogs); above the celiac artery, supraceliac group (9 dogs). Blood bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea nitrogen, and creatinine levels were measured before clamping and 5 minutes and 24 hours after reperfusion of the aorta. Bilirubin levels remained unchanged 5 minutes and 24 hours after reperfusion in all three groups. Alkaline phosphatase levels were significantly increased in all three groups 24 hours after reperfusion. ALT levels increased significantly in the supraceliac group and AST levels increased significantly in the infrarenal and supraceliac groups 24 hours after reperfusion of the aorta. However, despite these significant increases after reperfusion, the levels of these hepatic enzymes were still within the normal range for dogs. Urea nitrogen and creatinine levels showed that renal function did not change in any of the three groups. We conclude that supraceliac, infrarenal or suprarenal aortic clamping for 30 minutes do not promote any important changes in the hepatic or renal function of dogs.

[Influence of migration on the prevalence of serologic hepatitis B markers in a rural community. 2. Comparative analysis of various characteristics of the population studied]. / Influência da migração na prevalência de marcadores sorológicos de hepatite B em comunidade rural. 2-Análise comparativa de algumas caracteristicas das populações estudadas.

The association between prevalence of hepatitis B serological markers and birthplace, in a study carried out in a small rural county of S. Paulo State, Brazil, suggests different risk factors for hepatitis B between migrants and nonmigrant populations. These two groups were compared with regard to the following variables: level of education, professional occupation, number of previous hospitalizations, past history of blood transfusions and type of dental treatment. Migrants, mainly those from other states of Brazil, showed a low-level of education, a high proportion of people employed in agricultural activities, a higher number of past hospitalizations and higher exposure to blood transfusion and to more aggressive dental procedures. Associations were observed between the prevalence of serological markers and the following variables: level of education, professional occupation, number of previous hospitalizations and type of dental procedures, even though the last two associations did not justify the higher prevalences observed among migrants. The different distribution of hepatitis B markers seems to be dependent on the migrants' worse socio-economic condition, demonstrated by their lower level of education and by the predominance of secondary occupations.

[Influence of migration on the prevalence of serologic hepatitis B markers in a rural community. 1. Analysis of prevalence by birthplace]. / Influência da migração na prevalência de marcadores sorológicos de hepatite B em comunidade rural. 1-Análise da prevalência segundo local de nascimento.

Distribution of hepatitis B serological markers according to people's birthplaces and area of residence (urban/rural) was studied as a part of a field epidemiological research project carried out in Cássia dos Coqueiros, a small rural community of S. Paulo State, Brazil. The total prevalence of HBV markers was 7.7%, with rural showing a higher risk than urban inhabitants (9.8% as against 4.9%, respectively). Analysis of prevalence according to people's birthplaces revealed the highest value among those from other Brazilian states (15.8%), followed by people from other municipalities of the State of S. Paulo (9.2%). Those born in Cássia dos Coqueiros and particularly in Ribeirão Preto (the main city of the area, located 80 kilometers away), showed the lowest values of prevalence (5.2% and 2.5%, respectively). The importance of studying people's birthplaces when field epidemiological studies on hepatitis B are carried out is stressed. This variable is considered to be capable of exercising an influence on the natural history of the disease in a community, and may even explain differences in the distribution of markers in apparently similar populations.

[Correlation between maternal age, social class and smoking, and birth weight]. / Associação entre idade, classe social e hábito de fumar maternos com peso ao nascer.

An epidemiological survey was carried out in Ribeirão Preto, Brazil, from June 1978 to May 1979. Interviews were held with mother of singleton live borne children, delivered in hospitals, which accounted for 98% of all births in the area. The higher percentages of low birthweight children related to the offspring of smokers, young mother and women belonging to the working class. The majority of young women were found in the working class and the prevalence of smoking was higher in the group of women below 20 years of age. There was no statistical difference in the smoking habit as between different social classes. A larger number of low birthweight children were observed in nonsmoking women of the working class than among women smokers of the middle class. A log model was adjusted to the data in order to study the possible multiple association of smoking, maternal age and social class with birthweight. The results indicated that maternal smoking, maternal age and social class had independent effects on birthweight. The was no interaction between them. These findings suggest that the higher prevalence of low birthweight in nonsmoking mothers of the working class in relation to smoking mothers of the middle class probably reflects clustering of other risk factors-such as poor education inadequate prenatal care, high parity and differences in reproductive behavior in women of the working class.

[Prevalence of serological markers of hepatitis B in a small rural community of São Paulo State, Brazil]. / Prevalência de marcadores sorológicos de hepatite B numa pequena comunidade rural do Estado de São Paulo, Brasil.

Prevalence of three hepatitis B markers was measured by immunoassay techniques in small rural community of the State of S. Paulo, Brazil. Total prevalence was 7.74%, corresponding to values of 0.10%, 1.69% and 7.74% for HBsAg, anti-HBs and anti-HBc, respectively. The importance of anti-HBc determination in such studies is stressed. Comparisons between the low viral circulation observed in this area and high prevalences described in other rural communities may contribute to the raising of new hypothesis concerning alternative transmission mechanisms of hepatitis B.

[Perinatal health: low birth weight and social class]. / Saúde perinatal: baixo peso e classe social.

A survey was carried out in Ribeirão Preto, S. Paulo State, Brazil, between June 1978 and May 1979 with a view to studying the prevalence of low birth weight and its occurrence among different social classes. Data were collected from 8,878 singleton live births in eight maternity hospitals, accounting for 98% of all births in the area. Social classes were determinated by the use of a model proposed by Singer and modified for epidemiological purposes by Barros. Out of the 8,878 births, 660 (7.5%) were of low birth weight. The prevalence of deficient weight at birth (between 2,500 and 2,999 grams) was of 21.1%. Analysis indicated that 50.6% of children with low birth weight were at term and the majority of them suffered form intrauterine growth retardation. The prevalence of low birth weight according to social class was seen to be lower in the bourgeoisie classes (ranging from 2.8% to 3.9%) and higher in working classes (from 7% up to 9.5%). Low birth weight (defined as less than or equal to 2,500 grams) was used for purposes of comparison with other previous surveys. The percentage was lower in this study (8.3%) than that found in the Interamerican Investigation of Mortality in Childhood (8.7%), carried out in 1968-70. No statistically significant differences in the percentage of low birth weight were found in the case of Ribeirão Preto when these two surveys were compared.

Relaçäo entre a medida ecográfica da circunferência craniana fetal e a idade gestacional / Relationship between the ultrasound measurement of fetal skull circunference and gestational age

Em ecografias obstétricas, foram obtidas as circunferências cranianas (CC) de 654 fetos de gestaçäo normais e seus valores correlacionados com as idades gestacionais (IG). Foram calculados os percentis 5 e 95 para cada semana gestacional. A equaçäo da curva de regressäo ajustada aos dados foi: IG= 8,23 + 0,44C + 0,014CC2 onde IG é contada em semanas e CC em cm. Foi calculada a variabilidade de estimativa de IG para diferentes períodos de gestaçäo. Foram tabulados os valores de IG e seus limites de variabilidade, para os valores das CC conhecidos

Relaçäo entre a medida ecográfica da circunferência abdominal fetal e a idade gestacional / Correlation between the echographic measure of the fetal abdominal circumference and the gestational age

Obtivemos, ecograficamente, os valores da circunferência abdominal (CA) de 654 fetos normais durante a gestaçäo e os correlacionamos com os valores das idades gestacionais (IG). Calculamos os percentis 5 e 95, limites esperados para os valores da CA de fetos normais em cada idade gestacional. A equaçäo da curva de regressäo ajustada a estes valores é: IG = 6,04 + 0,902 CA + 0,0005 CA2 onde IG é contada em semanas e CA medida em cm. Tabulamos os valores da CA durante a gestaçäo, suas correspondentes e sua variabilidades

[Skull growth in children]. / Crescimento craniano na criança.

The authors review papers and researches about skull growth in newborns and infants: they analysed and correlated anthropometric data with maternal biological and social factors.