The association of genetic markers and malaria infection in the Brazilian Western Amazonian region.

Almost all individuals (182) belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil) were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D). The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings.

The association of genetic markers and malaria infection in the Brazilian Western Amazonian region

Almost all individuals (182) belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil) were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D). The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings

Ethnic admixture composition of two western Amazonian populations.

A small riverine community, Portuchuelo (8 degrees 37'S, 63 degrees 49'W), and a rural county, Monte Negro (10 degrees 15'S, 63 degrees 18'W), both in the state of Rondjnia, Brazil, were studied for the purposes of ascertaining health conditions and the causes of the variability of some infectious diseases. The sample included 181 inhabitants of Portuchuelo and 924 of Monte Negro. Data on 11 blood polymorphisms (ABO, Rh, MNSs, Kell, Fy, haptoglobin, hemoglobin, ACP1, PGM1, GLO1, and CA2) were used to determine the ethnic composition of the inhabitants of Portuchuelo and Monte Negro. The contributions of Africans, Amerindians, and Europeans to the ethnic composition of the studied populations were, respectively, 0.21 +/- 0.046, 0.44 +/- 0.064, and 0.35 +/- 0.069 in Portuchuelo; and 0.25 +/- 0.032,0.12 +/- 0.046, and 0.63 +/- 0.054 in Monte Negro.

A rural community in a Brazilian Western Amazonian Region: some demographic and epidemiological patterns.

Some demographic and epidemiological patterns of the rural population of Monte Negro, locality situated in the State of Rondônia (Brazil), Western Amazonia, are described based on a sample of 924 randomly selected individuals, approximately 10% of the whole population. The main features of this sample are (1) the illiteracy rates in the parental generation were 23% for fathers and 20% for mothers. Among children, this figure dropped to 6%; (2) housing in Monte Negro is characterized by being constructed with wood (92%), and also a floor (75%). Nevertheless, only 32% of these houses had electric energy; (3) the mean ages for the parental generation were 41.9 for males and 36.3 for females. These values for the offspring generation were 12.2 and 10.5, respectively; (4) the sex-ratio of the offspring generation was 1.32;(5) the bioassay of kinship was estimated as.033 for this long range migrant population; (6) the prevalence of some macrophage dependent infectious disease was conspicuously high; (7) the reported number of malarial episodes among males and females was statistically different, suggesting that malaria may be, in part, a "professional" disease; (8) the prevalence of serum-positive reactions against B-hepatitis is distressing. It has a strong age dependence and reaches 74% among adult males. Conversely, signs of active infection (AgHbs) rises to 16% among children.

A rural community in a Brazilian Western Amazonian region: some demographic and epidemiological patterns

Some demographic and epidemiological patterns of the rural population of Monte Negro, locality situated in the State of Rondônia (Brazil), Western Amazonia, are described based on a sample of 924 randomly selected individuals, approximately 10 percent of the whole population. The main features of this sample are (1) the illiteracy rates in the parental generation were 23 percent for fathers and 20 percent for mothers. Among children, this figure dropped to 6 percent; (2) housing in Monte Negro is characterized by being constructed with wood (92 percent), and also a floor (75 percent). Nevertheless, only 32 percent of these houses had electric energy; (3) the mean ages for the parental generation were 41.9 for males and 36.3 for females. These values for the offspring generation were 12.2 and 10.5, respectively; (4) the sex-ratio of the offspring generation was 1.32;(5) the bioassay of kinship was estimated as .033 for this long range migrant population; (6) the prevalence of some macrophage dependent infectious disease was conspicuously high; (7) the reported number of malarial episodes among males and females was statistically different, suggesting that malaria may be, in part, a "professional" disease; (8) the prevalence of serum-positive reactions against B-hepatitis is distressing. It has a strong age dependence and reaches 74 percent among adult males. Conversely, signs of active infection (AgHbs) rises to 16 percent among children

Twinning rate in a sample from a Brazilian hospital with a high standard of reproductive care.

CONTEXT: Epidemiological studies on twin births have been motivated mostly by the positive correlation between twinning rate and human fertility, prematurity, low birth weight, increased risk of infant death and long term risk for morbidity. OBJECTIVE: This paper intends to estimate the incidence of multiple births in a private hospital in Brazil with a high standard of reproductive care, and to evaluate the effects of maternal age, gestation order and assisted fertilization on twinning rate. DESIGN: Retrospective analysis. SETTING: First-class tertiary private hospital, São Paulo, Brazil. PARTICIPANTS: The multiple birth rate was investigated among 7,997 deliveries from 1995 to 1998, including 7,786 singletons, 193 twins, 17 triplets and one quadruplet. RESULTS: The rates per 1,000 dizygotic and monozygotic pairs and for triplets were estimated as 19.51, 4.50 and 2.13, respectively. The dizygotic and triplet rates were the highest observed in Brazil up to the present day. The twinning rate among primigravidae older than 30 years was very high (45.02 per 1,000) and was due to a disproportionately high frequency of dizygotic pairs. The triplet rate was also very high among the mothers of this age group (5.71 per 1,000). These facts are strong indicators that these women were the ones most frequently submitted to assisted reproductive techniques. The mean maternal age of the studied population was about six years higher than that estimated for mothers in the general population of southeastern Brazil. Primigravidae aged under 30 years as well as multigravidae showed similar twinning rates, which were almost 20 per 1,000. Among the deliveries of multigravidae older than 30 years, an unusually high frequency of monozygotic twins was observed (7.04 per 1,000), probably as a consequence of the residual effect of long-term use of oral contraceptives. CONCLUSIONS: The dizygotic twinning rate increased from 13.51 to 28.98 per 1,000 over the four years studied, with the twinning rate for primigravidae over 30 years old in 1998 being twice that observed in 1995. The mean maternal age was also high during this period, but the extremely high increase in twinning rate observed cannot be attributed solely to this variable. Assisted fertilization seems to be the most probable cause of this unusually high twinning rate.

No evidence of linkage between Mitsuda reaction and the NRAMP1 locus.

Thirty sib-pairs were ascertained through unrelated lepromatous probands. They consisted of 22 healthy individuals and 8 leprosy patients. The Mitsuda reactions of all sibs were evaluated both macroscopically and histologically, and high molecular weight genomic DNA was extracted from the white blood cells of all sib-pairs. Three DNA polymorphisms identified by polymerase chain reaction (274C/T, D543N, 1729 + 55del4) were used as chromosome markers at the NRAMP1 locus. Sib-pair comparisons did not disclose any sign of close linkage between the Mitsuda reaction and the genetic markers.

Genetic epidemiology of the Mitsuda reaction in leprosy.

This study comprised 544 nuclear families with 2,925 individuals tested for the Mitsuda reaction, from the Campinas region in Brazil. Segregation analyses suggest the segregation of a major gene (chi 2(1) = 0.07 - 0.07 = 0, p = 1), by failing to reject the hypothesis of Mendelian transmission and by rejecting the hypothesis of nontransmission of a major gene (chi 2(3) = 0.07 - 0.0 = 0.07, p > 0.99; chi 2(2) = 198.28 - 0.0 = 198.28, p < 0.0001).

Twinning rate in a southeastern Brazilian population.

The twinning incidence from 1984 to 1993 was investigated in Campinas, State of São Paulo, Brazil and the analyzed data were combined with previous series from the same population. This study has shown that the mean annual incidences and the standard deviations for DZ, MZ and DZ plus MZ twins for the period of 1984 to 1993 are estimated respectively as 4.7 +/- 0.92, 4.1 +/- 1.11, and 8.8 +/- 0.87 per 1,000. In the same period the mean annual incidence of triplets was 0.15 +/- 0.16. It was also shown that the incidence of DZ twins is steadily decreasing since 1925, while the incidence of MZ pairs, after a period of decline is increasing since the sixties, due perhaps to the widespread use of oral contraceptives. Concerning the twinning rate as a whole, it has been shown that its declining trend has disappeared over the last few years.

Investigation on seasonality of twin births in Brazil.

The hypothesis of seasonality of twin births was investigated in two important maternity hospitals in the State of São Paulo, Brazil. The study included 1,386 twin births that occurred among 154,699 deliveries from 1984 to 1993. No evidence of seasonality has been detected either for the twin birth rate considered as a whole or for dizygotic twinning rate. The distributions of these rates fitted well sinusoidal regression curves but the cyclic trend did not correspond to any specific season.

The genetic epidemiology of leprosy in a Brazilian population.

Data on leprosy patients have been obtained from the Dispensary of Leprosy of Campinas, São Paulo, where records on practically all cases of leprosy in the Campinas area during the period 1960-70 are filed. The whole sample comprises 10,886 individuals, distributed among 1,568 families. Complex segregation analysis was utilized to determine the nature of the genetic factors that may operate on leprosy and its subtypes. The results suggest the presence of a recessive major gene controlling susceptibility to leprosy per se, with frequency of approximately .05, although there are deviations from the expected Mendelian segregation proportions. Possible etiologic heterogeneity was examined by considering two subtypes separately: for lepromatous leprosy and tuberculoid leprosy there are suggestions for a segregating major effect; however, Mendelian transmission could not be demonstrated in either case. Therefore, there is no evidence to suggest unique genetic determinants for leprosy subtypes.

Annual variation of sex ratio in twin births and in singletons in Brazil.

The annual variation of the sex ratio (SR) of 1385 twin births was analyzed and compared to that of 85909 singletons. These births referred not only to live births but also to stillbirths in two southeastern Brazilian maternity hospitals from 1984 to 1993. While the annual variation of the SR of singletons was very small, that of twin births was extremely high, due to the significant heterogeneity of the annual data. It is suggested that the large SR annual variation of the twin birth might be a consequence of the variation of male or female monozygotic twins. The hypothesis that twin births show a lower sex ratio than singletons could be supported by the present data.

PIP: This article presents the findings of a study of the annual variation of the sex ratio among twin births compared to singleton births among a maternity population in two urban hospitals in Brazil. Data are obtained from hospital records from a maternity hospital in Campinas and Sao Paulo, Brazil, during 1984-93. There were 1385 twin births and 85,909 singleton births delivered during 1984-93 in these maternity hospitals in Sao Paulo state. Deliveries included stillbirths weighing 500 g or more. Findings indicate that the sex ratio of singletons was 104.6 males per 100 females. The sex ratio of the 763 twins born in Campinas and the 622 twins born in Sao Paulo showed considerable variation from the mean sex ratio of singleton births. The mean sex ratio among twins in Campinas was 107.1 males per 100 females, with a standard deviation of 20.4 in Campinas and 29.7 in Sao Paulo. There were significant differences from the mean sex ratio among twin births in Campinas in 1984 and 1989 and in Sao Paulo in 1984, 1985, 1988, and 1989. There was significant heterogeneity of sex ratios among twin births even with pooled data. The mean of pooled data on twin births was 102.9 males per 100 females, with significant differences from the mean in 1984, 1985, and 1987. The application of Woolf's test indicated heterogeneity in the data and no effect on the sex ratio from twin births. Maternal age was negatively correlated with the sex ratio of twin births. It is argued that monozygotic twins were not primarily females and that twin births did not have a lower sex ratio than singleton births.

Factors influencing human birth weight in normal pregnancy: a prospective study in a brazilian university hospital

Os efeitos de 17 variáveis sobre o peso do recém-nascido foram analisados em um estudo prospectivo de 1.045 crianças sem malformaçöes graves, nascidas de parto único em um hospital-escola brasileiro de mäes sem diabetes mellitus e sem hipertensäo crônica. Essas variáveis foram as seguintes: sexo do recém-nascido, idade gestacional por ocasiäo do parto, tipo de parto, ordem de nascimento, forma da placenta, peso da placenta, comprimento do cordäo umbilical, ponto de inserçäo do cordäo umbelical na placenta, grau de consangüinidade entre os genitores do recém-nascido, cor da pele da mäe, estatura materna, idade materna, idade paterna, trimestres de acompanhamento pré-natal, número médio de cigarros fumados por dia durante a gravidez, escolaridade materna e nível sócio-econômico da família do recém-nascido. As inter-relaçöes dessas variáveis foram analisadas para investigar sua importância relativa na determinaçäo da variabilidade do peso ao nascer. Somente a idade gestacional, o peso da placenta, o tabagismo durante a gravidez, a estatura materna, o sexo do recém-nascido e a ordem de nascimento foram retidos como fatores com influência significativa sobre o peso do recém-nascido e capazes de explicar 60 por cento de sua variância total. Desses fatores, a idade gestacional e o peso da placenta säo os mais importantes porque explicaram, respectivamente, 40 por cento e 16 por cento da variância total do peso ao nascer

Possible discrimination between genotypes of lactase persistence phenotype

A persistência da atividade da lactase na vida adulta tem sido aceita como um fenótipo autossômico dominante. Uma investigaçäo da frequência da hipolactasia do tipo adulto em caucasóides brasileiros sugere, entretanto, que, entre os indivíduos capazes de absorver lactose, os homozigotos podem ser distinguidos dos heterozigotos. Um teste de tolerância à lactose foi realizado em 88 voluntários adultos, sendo a glicemia determinada em amostras de sangue venoso colhido antes e 20, 40 e 60 minutos depois do teste. Ao invés da esperada distribuiçäo bimodal, a distribuiçäo do aumento máximo da glicemia (MBGR) dos indivíduos examinados sugeriu trimodalidade correspondente a três fenótipos: a hipolactasia do tipo adulto (MBGR menor que 16 mg%), a persistência da atividade da lactase heterozigótica (MBGR entre 16 e 56 mg%) e a persistência da lactase homoizigótica (MBGR igual ou superior a 56 mg%). A distribuiçäo observada e a esperada de acordo com a lei de Hardy e Weinberg mostraram bom ajustamento