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PubMed1999

SEARCH international case-control study of childhood brain tumours: role of index pregnancy and birth, and mother's reproductive history.

A series of co-ordinated population-based case-control studies of childhood brain tumours (CBT) was undertaken under the auspices of the Surveillance of Environmental Aspects Related to Cancer in Humans (SEARCH) programme of the International Agency for Research on Cancer (IARC) to evaluate, inter alia, the risk in relation to characteristics of the index pregnancy and birth, and maternal reproductive history. Subjects comprised 1218 cases aged 0-19 years and 2223 controls. Risk estimates were calculated by unconditional logistic regression, adjusted for age, sex, centre and mother's years of schooling, for all types of CBT combined as well as for four groups defined by histopathology (astrologlial tumours, primitive neuroectodermal tumours of the brain, 'other glial' tumours and 'other histological types') and for five age groups (0-1, 0-4, 5-9, 10-14, 15-19 years). Use of anaesthetic 'gas' was associated with an increased risk of CBT (OR = 1.5, 95% CI [1.1, 2.0]), apparent in children aged 0-4 years (OR = 2.4, 95% CI [1.4, 4.1]) and for astroglial tumours (OR = 1.6, 95% CI [1.1, 2.2]) with non-significantly increased relative risks for each of the other histological groups. However, not all centre-specific relative risks were elevated. No other aspect of the index pregnancy, delivery and early neonatal period or of the mother's previous reproductive history was associated with risk for CBT.

Adolescent↗
PubMed1988

[Heritability of fertility in human populations and the structure of Crow's index].

Heritability of fertility was determined in populations with natural character of reproduction (Middle Asia Republics) and in populations with family planning (Middle Russia). The material was collected by interviewing the married women of postreproductive age. The heritability of fertility was estimated as a doubled coefficient of correlations between sisters for effective fertility. In populations with natural character of reproduction the heritability was about 50% and it did not differ from O in the populations with family planning. The values of heritability were used in the components of the Crow index analysis. The main contribution into broad-sense heritability of fertility comes from additive component, as shown in an Asia population (Turkmen). The values of heritability of fecundability (86%) and of postpartum sterility (66%) have been calculated for the same population.

Asia, Central↗
PubMed2003

[Frequency of altered male factor in an infertility clinic].

UNLABELLED: Infertility is the incapacity of a couple to conceive after a year of regular sexual life without using a method for family planning. The infertility state is dependent on the female factor as well as masculine factor; an altered masculine factor is designated when any cause or causes of infertility reside in the male. The masculine factor as a cause of infertility is present in 40 to 50% of cases hence the importance of an integral evaluation of male alterations and its fertility. The World Health Organization (WHO) has proposed to classify the masculine infertility based on semen features. OBJECTIVE: To determine the frequency of the masculine factor altered in association to diagnosed abnormalities, according to the number of affected seminal indexes based on seminograms performed in infertile patients seen at the department of Human Reproductive Medicine, Hospital Juárez de México. MATERIAL AND METHODS: An observational, descriptive, transverse, retrospective study was performed. SUBJECTS: the seminograms practiced were reviewed from 571 clinical files of couples that the consultation for infertility from January 1993 to February 2001. Collection and analysis of semen samples was based on standards settled by WHO. RESULTS: Of 571 seminogram informs, 371 (65%) showed alterations in the seminal indexes, the stocking of age of this group was of 31.89 years +/- SD 6.3 years. Our findings were: azoospermia in 89 (23.98%), astenonecrozoospermia in 44 (11.85%), hypospermia in 43 (11.59%), astenozoospermia in 33 (8.89%), oligoastenozoospermia in 31 (8.35%) hyponecrozoospermia in 30 (8.08%), oligozoospermia in 25 (6.73%), others in 21 (5.7%), necrozoospermia in 19 (5.12%), hypoastenozoospermia in 18 (4.85%), cryptozoospermia in 11 (2.97%), and hypooligoastenozoospermia in 7 (1.88%). In 62.6% of seminograms practiced there was an isolated alteration, in 34.4% two alterations and in the remaining 3% more than two alterations. CONCLUSION: We found masculine factor altered in 65% of couples who were requiring consultation for infertility. The three main alterations of seminal indexes were azoospermia, astenonecrozoospermia and hypospermia.

Adolescent↗
PubMed1964

THE HUMAN BLOOD INDEX OF MALARIA VECTORS IN RELATION TO EPIDEMIOLOGICAL ASSESSMENT.

The human blood index, or estimated proportion of the blood meals of a mosquito population obtained from man, is provisionally assessed for certain anophelines from blood-meal samples collected during the period 1959-62 and subjected to precipitin testing at the Lister Institute. In malaria eradication programmes this index is relevant to epidemiological assessment and to the modification of measures to interrupt transmission, since a mosquito's vectorial capacity and the malaria reproduction rate both vary as the square of the human blood index.There are serious difficulties in achieving representative sampling for this index and in interpreting the index obtained. These are discussed in some detail. In practice, the human blood index is often best estimated by applying the unweighted mean of a part-sample collected from human dwellings and one from other types of resting-place.Applying this calculation to the samples under review, it appears that DDT exerts a moderate, and dieldrin a more pronounced, impact on the human blood index of Anopheles gambiae and A. funestus; such an effect, indeed, may be general in house-visiting anophelines. Some 18 anopheline species are tentatively graded as having low, medium or high natural human blood indices. Regular and careful sampling, combined with recording of all relevant information, is recommended in view of the epidemiological and operational importance of the human blood index in assessment of eradication programmes.

Animals↗
PubMed2006

Density-dependent host choice by disease vectors: epidemiological implications of the ideal free distribution.

The proportion of vector blood meals taken on humans (the human blood index, h) appears as a squared term in classical expressions of the basic reproduction ratio (R(0)) for vector-borne infections. Consequently, R(0) varies non-linearly with h. Estimates of h, however, constitute mere snapshots of a parameter that is predicted, from evolutionary theory, to vary with vector and host abundance. We test this prediction using a population dynamics model of river blindness assuming that, before initiation of vector control or chemotherapy, recorded measures of vector density and human infection accurately represent endemic equilibrium. We obtain values of h that satisfy the condition that the effective reproduction ratio (R(e)) must equal 1 at equilibrium. Values of h thus obtained decrease with vector density, decrease with the vector:human ratio and make R(0) respond non-linearly rather than increase linearly with vector density. We conclude that if vectors are less able to obtain human blood meals as their density increases, antivectorial measures may not lead to proportional reductions in R(0) until very low vector levels are achieved. Density dependence in the contact rate of infectious diseases transmitted by insects may be an important non-linear process with implications for their epidemiology and control.

Animals↗
PubMedDate not supplied

Gender differences in leptin levels and physiology: a role for leptin in human reproduction.

Leptin, an adipocyte-derived hormone known to play an important role in body-weight regulation, has been shown to be expressed differentially in men and women. These observations are potentially important for the understanding of differences between men and women in regulation of food intake, weight gain, and body fat distribution. Leptin is also involved in female fertility, especially in pubertal development. It may well be the triggering signal for the onset of puberty in girls. Although the exact mechanisms and interactions with sex steroids are not yet fully established, it is clear that leptin plays a role as an endocrine mediator in sexual development and reproduction.

Animals↗
PubMed2006

[Endometrial receptivity: numerical classification to successful prognosis in assisted reproduction programs].

BACKGROUND: Currently, the most precise way of predicting uterine receptivity is the histopathological study through endometrial biopsy. Endometrial morphology and thickness are the factors most strongly associated with better pregnancy rates. OBJECTIVE: To evaluate the prediction value of a numerical grade to predict pregnancy in patients exposed to assisted reproductive techniques. PATIENTS AND METHODS: 22 cycles of in vitro fertilization were made at the Instituto para el Estudio de la Concepción Humana in Monterrey, Nuevo León, from June 2003 to January 2004. We evaluated and categorized: endometrial thickness and morphology, vascularity, miometrial ecogenicity, and uterine artery blood flow (including pulsatility and resistance indexes, presence of protodyastolic nicks, and telediastolic flow). The final numerical grade result from the sum of the individual values obtained for each factor. RESULTS: We included 22 cycles of 20 patients. The general pregnancy and implantation rate was of 40 (8/20) and 26% (17/65) per cycle, respectively. The most common diagnosis was tube occlusion (28%), followed by masculine sex (24%), endometriosis (14%), anovulation (14%), and inexplicable (14%). There were no statistical differences among the pregnant and non-pregnant groups regarding: age, hormonal profile (FSH and estradiol, basal and at the tenth day), total of recombinant FSH unities, follicles > or = 14 mm the day of applying human chorionic gonadotropin, aspired eggs, fertilization index, and transferred embryos. CONCLUSIONS: Endometrial maturity is essential for implantation during an assisted reproductive procedure.

Adult↗
PubMed1998

Diurnal variation of the serum leptin concentration in patients with anorexia nervosa.

OBJECTIVE: In rodents, leptin is involved in regulating eating behaviour, fat storage, and reproductive function. In humans, the serum leptin concentration in obese and normal weight subjects correlates with body mass index, reflecting the body fat store. The serum leptin exhibit diurnal variation, however, this has been reported to be absent in normal weighted amenorrheic athletes. Anorexia nervosa is associated with multiple endocrine abnormalities. Hypothalamic amenorrhoea often precedes the weight loss and may persist after weight recovery. We hypothesized that leptin could be involved in the regulation of eating behaviour and gonadal function in anorexia nervosa. DESIGN: We measured the concentration of leptin in serum samples taken after an overnight fast in 18 female anorexia nervosa patients and 11 controls. To study diurnal variation, eight patients and 11 controls were hospitalized for 24 h and had a standardized diet at regular times. Seven blood samples were obtained at 4 h intervals from each subject. PATIENTS: The patients fulfilled the DSM-IV criteria for anorexia nervosa. The mean body mass index for the patients was 14.2 +/- 2.3 kg/m2 and for controls 20.3 +/- 1.7 kg/m2. RESULTS: The mean fasting leptin concentration as well as the 24 h mean concentration were significantly lower in the anorectic group than in the control group (2.5 +/- 0.9 vs 10.1 +/- 6.1 micrograms/l, P < 0.01 and 2.7 +/- 1.5 vs 10.6 +/- 7.1 micrograms/l, P < 0.01 respectively). In the whole group of subjects (n = 28) a significant positive correlation between the leptin level and body mass index was found (r = 0.63, P < 0.001). In the anorectic group it was found that the leptin level correlated better with body fat percentage than with body mass index. In normalized data the time course of the mean leptin levels showed a monophasic variation with nadir and zenith at about 0900 and 0100 h respectively. However, the individual coefficients of variance were significantly lower in the anorectic group compared to the group of healthy women. CONCLUSION: In patients with anorexia nervosa the leptin level is low, reflecting the low body fat mass, and the relative diurnal variation is strikingly reduced. The similarity to that of normal weighted women with hypothalamic amenorrhoea suggest that altered leptin oscillations may be of particular significance in the hypothalamic regulation of reproductive function.

Adolescent↗
PubMed1994

Determinants of body mass index: a study from northern Italy.

Overweight and obesity are associated with increased mortality and morbidity, and human weight is influenced by multiple factors, both genetically and environmentally determined. We investigated the influence of some socioeconomic, behavioral, dietary and reproductive factors on body mass index (BMI). Data were obtained from a comparison group of a case-control study of gastrointestinal cancers from the four largest teaching and general hospitals in Milan, northern Italy. The subjects were 1,188 men and 832 women admitted between January 1985 and June 1992 to the hospitals under study for diseases other than malignant or digestive and not known or suspected to be related to alcohol or tobacco. The following were measured: BMI (Quetelet's index, weight, kg/height, m2) and the corresponding standard errors (s.e.) in strata of selected variables, linear regression coefficients (beta) and correlation coefficients between BMI and each variable. Mean BMI increased with age until 35-44 years in men and 45-54 years in women. In both sexes BMI was inversely associated with education and social class. Smokers tended to be leaner than non-smokers, but no consistent trend was observed with increasing numbers of cigarettes. Alcohol drinkers had mean BMI similar to non-drinkers, except heavy drinking women who were lighter. BMI was not significantly associated with coffee, decaffeinated coffee, tea, bread, vegetable and fruit consumption. No relation was observed between total estimated caloric intake and BMI. In women BMI was directly associated with marriage and number of children, and inversely with oral contraceptive use.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Restoration of reproductive potential by lifestyle modification in obese polycystic ovary syndrome: role of insulin sensitivity and luteinizing hormone.

Weight reduction and exercise have been shown to help with menstrual disturbance and infertility in obese women with polycystic ovary syndrome. We studied the relationship between insulin sensitivity and ovulation patterns in 18 infertile anovulatory obese polycystic ovary syndrome (PCOS) women (NO) with normal glucose tolerance, aged between 22-39 yr with a body mass index of 27-45 kg/m2, before and after a 6-month diet and exercise program. This program promotes healthy lifestyle factors, but does not lead to rapid weight loss. The anthropometric, metabolic, and endocrine factors of these subjects were compared to those of 10 age- and weight-matched PCOS women with regular monthly ovulation (RO). Before lifestyle modification, the anovulatory subjects had greater central obesity than regular ovulators, as assessed by percent central fat (NO, 45.7 +/- 0.8%; RO, 42.2 +/- 1.6%; P < 0.05), higher glucose increment after glucose challenge (NO, 10.1 +/- 1.0 mmol/L; RO, 6.4 +/- 1.1 mmol/L; P < 0.02), lower insulin sensitivity index (NO, 1.2 +/- 0.2; RO, 2.8 +/- 0.6 micromol/kg x min/pmol/L; P < 0.005), higher plasma LH (NO, 8.9 +/- 0.9; RO, 4.6 +/- 0.9 IU/L; P < 0.005), and lower plasma sex hormone-binding globulin (NO, 18.0 +/- 2.5; RO, 27.8 +/- 5.7 nmol/L; P < 0.05]. Anovulatory subjects were classified as responders (R) to the intervention if they regained ovulation during the study. As a result of intervention, R showed an 11% reduction in central fat, a 71% improvement in insulin sensitivity index, a 33% fall in fasting insulin levels, and a 39% reduction in LH levels. None of these parameters changed significantly in nonresponders (NR). At the end of the study, R had lower fasting insulin (R, 13.6 +/- 1.7; NR, 23.0 +/- 3.5 mU/L) and LH levels (R, 5.0 +/- 1.7; NR, 7.4 +/- 1.4 IU/L), but similar androgen levels compared to NR. We conclude that lifestyle modification without rapid weight loss leads to a reduction of central fat and improved insulin sensitivity, which restores ovulation in overweight infertile women with PCOS. Lifestyle modification is the best initial management for obese women seeking to improve their reproductive function.

Adult↗
PubMed1997

Women's reproductive health: the role of body mass index in early and adult life.

BACKGROUND: Higher risks of menstrual problems and infertility have been found in underweight and overweight women but evidence is inconsistent especially in relation to the effect of age of onset of obesity. OBJECTIVE: To determine whether body mass index (BMI) in adulthood or childhood affects the reproductive health of women. METHODS: Heights, weights (at 7, 11, 16, 23 and 33y) and reproductive data were available for 5799 females in the 1958 British birth cohort study. Body mass index (BMI) was calculated as weight/height2. Age-specific cut-offs were used to define overweight and obesity. Reproductive outcomes reported at age 33 included: menstrual problems (also reported at 16y), hypertension in pregnancy and subfertility. RESULTS: Early menarcheal age was associated with higher risks of menstrual problems by 16y but this relationship did not persist to 33y. Obesity at 23y and obesity at 7y both independently increased the risk of menstrual problems by age 33 (OR = 1.75, OR = 1.59 respectively) after adjusting for other confounding factors. Obesity at 23y increased the risk of hypertension in pregnancy (OR = 2.37), after adjusting for confounders. Consistent with these findings, obese women at 23y were less likely to conceive within 12 months of unprotected intercourse after adjustment for confounders (RR = 0.69). CONCLUSIONS: Overweight and obesity in early adulthood appears to increase the risk of menstrual problems, hypertension in pregnancy and subfertility. Other than menstrual problems, childhood body mass index had little impact on the reproductive health of women.

Adolescent↗
PubMed2002

Functional consequences of adult malnutrition in developing countries: a review.

Credible concepts of malnutrition depend critically on evidence that functional impairment differentiates variation in size from unacceptable abnormality. This paper reviews functional studies on capacity for work, mortality, reproductive outcomes, competitive success, and cultural preferences. Future research priorities should include the comparative significance of simple physical dimensions in distinct ethnic groups for long-term biological and socioeconomic outcomes, and the relationships between the biological and cultural significance of variation in physique.

Adult↗
PubMed2004

Statics and dynamics of malaria infection in Anopheles mosquitoes.

The classic formulae in malaria epidemiology are reviewed that relate entomological parameters to malaria transmission, including mosquito survivorship and age-at-infection, the stability index (S), the human blood index (HBI), proportion of infected mosquitoes, the sporozoite rate, the entomological inoculation rate (EIR), vectorial capacity (C) and the basic reproductive number (R0). The synthesis emphasizes the relationships among classic formulae and reformulates a simple dynamic model for the proportion of infected humans. The classic formulae are related to formulae from cyclical feeding models, and some inconsistencies are noted. The classic formulae are used to to illustrate how malaria control reduces malaria transmission and show that increased mosquito mortality has an effect even larger than was proposed by Macdonald in the 1950's.

Animals↗
PubMed2003

Attitudes toward prenatal diagnosis, termination of pregnancy, and reproduction by parents of children with nonsyndromic oral clefts in Argentina.

OBJECTIVE: To investigate the attitudes of Argentine parents of children with nonsyndromic oral clefts with respect to prenatal diagnosis, termination of pregnancy, and reproduction and to assess the variables that might influence their responses. DESIGN: One hundred and sixty-five parents of children with oral clefts, ascertained from a craniofacial clinic in the suburbs of Buenos Aires, answered a 151-item semistructured questionnaire. The questionnaire included sections covering sociodemographic information, level of religiousness, characteristics of the child's cleft, parental perception of their child's cleft, pregnancy history, recurrence risk, access to health care, attitudes in regard to abortion, and family environment. RESULTS: Most parents (60%) believe their child's cleft is not a serious condition. None of the respondents would terminate a pregnancy because the ultrasound reveals an oral cleft. Similarly, very few (6.1%) would terminate the pregnancy if there were an early diagnosis of Down syndrome. Half of the respondents believe that abortion should not be an option for any couple expecting a child. CONCLUSIONS: Most respondents do not perceive oral clefts as a severe condition. Parents would not choose to terminate the pregnancy over delivery of such an affected newborn.

Abortion, Induced↗