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PubMedDate not supplied

Proximate determinants of fertility in Nigeria.

Data from the 1981-82 Nigeria Fertility Survey (NFS) are used to identify the key proximate determinants of fertility in Nigeria. The patterns of their individual and collective effects are analyzed in a search for possible sources of fertility change. Exposure to the risk of childbearing through first marriage is found to be the most important proximate determinant of Nigerian fertility. Subsequent to marriage, fertility is determined mainly by breastfeeding and postpartum sexual abstinence. Where fertility shows significant socioeconomic variations, there are equally identifiable patterns of the impact of the proximate determinants which explain these differentials to a large extent. On a national scale, the observed patterns of the impact of the measured proximate determinants do not appear to suggest that Nigerian fertility is soon to experience a large decline.

Adolescent↗
PubMed1987

Anthropometry and subsequent mortality in groups of children aged 6-59 months in Guinea-Bissau.

To assess the importance of nutritional status for subsequent survival, 2228 children aged 6-59 mo were followed for 8-12 mo in four different areas of Guinea-Bissau. The overall death rate was 0.62/100 child-months of follow-up (126 deaths) and 0.63 for the 1756 children who were examined on entering the study (109 deaths). Mortality was twice as high in the periurban as in the rural areas due to an outbreak of measles. In a bivariate analysis the relationship between nutritional status indicators and mortality was confounded by the age dependence of both. Using Cox's regression technique, height-for-age but not weight-for-height was positively correlated with survival. The number of children in the household was a better discriminator for death from measles than was nutritional status. Long-term factors, probably of multiple social origin, are likely causes of both relatively short stature and high mortality.

Body Height↗
PubMed1983

Egg-laying defective mutants of the nematode Caenorhabditis elegans.

We have isolated 145 fertile mutants of C. elegans that are defective in egg laying and have characterized 59 of them genetically, behaviorally and pharmacologically. These 59 mutants define 40 new genes called egl. for egg-laying abnormal. Most of the other mutants are defective in previously identified genes. The egl mutants differ with respect to the severity of their egg-laying defects and the presence of behavioral or morphological pleiotropies. We have defined four distinct categories of mutants based on their responses to the pharmacological agents serotonin and imipramine, which stimulate egg laying by wild-type hermaphrodites. These drugs test the functioning of the vulva, the vulval and uterine muscles and the hermaphrodite-specific neurons (HSNs), which innervate the vulval muscles. Mutants representing 14 egl genes fail to respond to serotonin and to imipramine and are likely to be defective in the functioning of the vulva or the vulval and uterine muscles. Four mutants (representing four different genes) lay eggs in response to serotonin but not to imipramine and appear to be egg-laying defective because of defects in the HSNs; three of these four were selected specifically for these drug responses. Mutants representing seven egl genes lay eggs in response to serotonin and to imipramine. One egl mutant responds to imipramine but not to serotonin. The remaining egl mutants show variable or intermediate responses to the drugs. Two of the HSN-defective mutants, egl-1 and her-1(n695), lack HSN cell bodies and are likely to be expressing the normally male-specific program of HSN cell death. Whereas egl-1 animals appear to be defective specifically in HSN development, her-1(n695) animals exhibit multiple morphological pleiotropies, displaying partial transformation of the sexual phenotype of many cells and tissues. At least two of the egl mutants appear to be defective in the processing of environmental signals that modulate egg laying and may define new components of the neural circuitry that control egg laying.

Animals↗
PubMed1988

Case-control studies of the effect of environmental sanitation on diarrhoea morbidity: methodological implications of field studies in Africa and Asia.

The problems and prospects in the use of case-control studies to assess the effects of improvements in environmental sanitation on diarrhoea morbidity are discussed on the basis of two field studies. It is concluded that an adequate design is available for assessing the effects of a single improvement on diarrhoeal disease. The estimates of effect appear to be valid and sufficiently precise. For addressing more complex questions of interactions, sample sizes would have to be increased substantially. The experience with two field studies suggests that there is hope that a simpler protocol may be feasible, in which only limited information is collected, in which few home visits are made, and in which analytical techniques are simple. Until more field studies have been conducted definitive conclusions cannot be reached on the applicability of such a simple, rapid and inexpensive approach.

Child, Preschool↗
PubMed1992

Menstrual function after tubal sterilization.

More than 10 million women in the United States have undergone tubal sterilization. There has been concern that this procedure may increase the risk of later menstrual dysfunction. The Collaborative Review of Sterilization (CREST) is a large, multicenter, prospective study of tubal sterilization in the United States. This report describes CREST participants who were interviewed immediately before sterilization and again in annual poststerilization interviews for up to 5 years between 1978 and 1988. The authors analyzed reported changes in six menstrual cycle characteristics for 5,070 women undergoing interval sterilizations. Longitudinal, multivariate regression was used to adjust for baseline menstrual function and other potential confounders. Five years after sterilization, 35% of the CREST participants reported high levels of menstrual pain, 49% reported heavy or very heavy menstrual flow, and 10% reported spotting between periods. In contrast to the fifth year, the first year of follow-up was similar to presterilization menstrual function; in the first year, 27% of participants reported high menstrual pain, 41% reported heavy menstrual flow, and 7% reported spotting. These findings may be affected by aging of the cohort and other study limitations, but they suggest that if tubal sterilization leads to changes in menstrual function, such changes may take some time to develop.

Adolescent↗
PubMed1999

Responsiveness of outcome measures in juvenile chronic arthritis. Italian Pediatric Rheumatology Study Group.

OBJECTIVE: To examine the responsiveness of the disease activity measures more commonly used in juvenile chronic arthritis (JCA) clinical trials. METHODS: Data were obtained from an open-label, non-controlled, multicentre trial designed to investigate the efficacy of methotrexate (MTX) in children with JCA. Outcome measures, including physician and parent global assessments, functional ability measures, articular variables, and laboratory indicators of systemic inflammation, were assessed at baseline and after 6 months of MTX treatment in 132 patients. Responsiveness of endpoint variables was evaluated by assessing the effect size (ES) and the standardized response median (SRM). RESULTS: Physician and parent global assessments were the more responsive instruments, showing ES and SRM above 1.0. Erythrocyte sedimentation rate, C-reactive protein, functional status measures and articular variables showed intermediate responsiveness. Morning stiffness, haemoglobin and platelet count were the least responsive instruments. CONCLUSION: The results of our analysis indicate that subjective estimations of the disease activity, either by the physician or parents, are the most responsive instruments in the assessment of the therapeutic response in children with JCA. The responsiveness of outcome measures in JCA should be further investigated in prospective controlled studies.

Adolescent↗
PubMed2005

Audiometric threshold shift definitions: simulations and suggestions.

OBJECTIVES: Determine (1) whether pure-tone average (PTA) or "any frequency" (AF) definitions of significant threshold shift (STS) are more accurate under different conditions; (2) whether STS definitions applied twice are more accurate than when applied once; (3) whether three surrogate analysis methods applicable to real-world audiometric data can appropriately measure the accuracy of STS definitions; and (4) whether evidence from previous studies supports a change in the current STS definition used by the Occupational Safety and Health Administration (OSHA); (5) make recommendations for future research. DESIGN: Computer simulation of periodic audiograms, with typical test-retest variability, from seven groups of individuals (N = 1000 each), with or without threshold shifts of different sizes at different frequencies; receiver operating characteristic area analysis to determine relative accuracy of PTA and AF decision variables, applied once or twice; testing of surrogate methods (confirmation, variability, and comparison) against receiver operating characteristic areas in estimation of accuracy of decision variables; review of previous studies, considering the limitations of the surrogate methods that were used. RESULTS: Either AF or PTA definitions may be preferable, depending on whether the genuine threshold shift has occurred at a single frequency or across a range of frequencies. Including too few or too many frequencies degrades the performance of both AF and PTA variables. An STS decision variable performs only slightly better when applied twice than when applied once. The surrogate methods can be useful, but all have important caveats: The comparison method is best, but only when an appropriate control group is available; the variability method is intermediate but requires that each decision variable be tested at multiple criterion values for reliable results. The confirmation method, which was the least accurate in assessing true performance, also requires testing at multiple levels. Even when this is done, it markedly exaggerates the benefit of applying an STS definition twice and makes STS definitions that identify large numbers of individuals falsely appear to be more accurate than definitions that identify smaller numbers of individuals. Taking these caveats into account, previous studies do not offer convincing evidence for a change in the current OSHA STS definition. CONCLUSIONS: Choice of an STS definition requires three judgments that cannot be made based on the type of analysis discussed in this report: The range of frequencies to be tested, whether to require that an STS definition be applied twice, and the acceptable magnitude of false-positive error. Once these judgments have been made, the techniques discussed here can assist in selecting the appropriate decision variable (typically PTA or AF) and a criterion value that yields an acceptable false-positive rate. Additional research using the techniques described in this report with either new or old audiometric databases could help determine whether any STS definition is significantly better than the current OSHA definition.

Audiometry, Pure-Tone↗
PubMed1994

Expression and distribution of transforming growth factor-alpha within melanocytic lesions.

Stimulation of epidermal growth factor (EGF) receptor by ligands such as transforming growth factor (TGF) alpha may be associated with cell proliferation or transformation in both nevocytes and keratinocytes. Previously, EGF receptors have been identified within a variety of pigmented lesions, suggesting a possible responsiveness to ligands such as TGF alpha. In the present study, we characterize the intralesional expression and distribution of immunoreactive TGF alpha protein by avidin-biotin immunoperoxidase localization in benign nevi, congenital nevi, dysplastic nevi, and malignant melanomas. In situ hybridization techniques with TGF alpha riboprobes confirmed the constitutive production of TGF alpha in all types of pigmented lesions. The localization of TGF alpha expression to nevocytes when coupled with the previous reports of expression in basal keratinocytes suggests the possibility of either an autocrine mechanism of action for TGF alpha or a paracrine interplay of TGF alpha between keratinocytes and nevocytes within melanocytic lesions. An increase in immunoreactive TGF alpha in nevocytes was noted in both benign and dysplastic nevi from dysplastic nevus patients, as compared to benign nevi from normal patients. Congenital nevi and malignant melanomas showed an intermediate and variable level of TGF alpha immunoreactivity. When coupled with previous studies the data suggest linkage of the TGF alpha/EGF receptor pathway in the evolution of melanocytic lesions.

Adolescent↗
PubMed1998

Stepwise health surveillance for bronchial irritability syndrome in workers at risk of occupational respiratory disease.

OBJECTIVES: Questionnaires, lung function tests, and peak flow measurements are widely used in occupational health care to screen for subjects with respiratory disease. However, the diagnostic performance of these tests is often poor. Application of these tests in a stepwise manner would presumably result in a better characterisation of subjects with respiratory disease. METHODS: Cross sectional data from workers exposed to acid anhydrides, to laboratory animals, and to flour dusts were used. Sensitivity and specificity were calculated from cross tables of different (combinations of) tests for bronchial hyperresponsiveness and bronchial irritability in the past four weeks (BIS). From sensitivity and specificity likelihood ratios were computed and change in probability of BIS was calculated. RESULTS: The prevalence of BIS was 7%, 7%, and 5%, respectively. In all groups questionnaire data provided excellent sensitivity but poor specificity, which was inherent on the broad definition of symptoms. Adding the forced expiratory volume in one second/forced vital capacity (FEV1/FVC) ratio yields almost perfect specificity, and peak expiratory flow (PEF) variability is intermediate in populations in which smoking induced or non-allergic respiratory diseases predominates. In occupational groups in which asthma is a problem, adding PEF measurements will optimise sensitivity and specificity in detection of BIS. The probability of BIS for subjects with a negative combined test outcome was lower than the probability before testing. Subjects with a positive combined test outcome had a probability of BIS after the tests at least three times the probability before. CONCLUSIONS: Combined testing yields better sensitivity and specificity. An advantage of combined testing is an economy in the effort to screen for subjects with BIS. Combined testing resulted in more detailed estimation of the probability of BIS.

Anhydrides↗
PubMed1990

Fertility in anthropological populations.

"In this review I draw upon statistical demography and, to a lesser extent, reproductive endocrinology to formulate a coherent strategy for investigating fertility and reproduction in anthropological populations. The object, it must be emphasized, is not to reduce anthropology to demography or endocrinology, but rather to acquaint anthropologists with a powerful set of tools with which they can address issues of anthropological interest." The author first discusses the concept of natural fertility. Next, he summarizes the most significant generalizations concerning variations in fertility among preindustrial societies using the concept of proximate determinants developed by John Bongaarts. Finally, he outlines an alternative approach that might be more suited to the analysis of such fertility variations.

Anthropology↗
PubMed1996

Primary malignant melanoma of the sinonasal cavity: MR imaging evaluation.

To evaluate the magnetic resonance (MR) imaging characteristics of primary malignant melanoma of the sinonasal cavity, T1- and T2-weighted MR images of 12 patients with primary sinonasal melanoma were retrospectively reviewed. Gadolinium-enhanced imaging was performed in seven cases. The MR images were compared with histopathologic results. There were seven melanotic melanomas and five amelanotic melanomas; hemorrhage was present in three melanotic and two amelanotic melanomas. The seven melanotic melanomas were hyperintense to gray matter on T1-weighted images (whether hemorrhage was present or not), consistent with the paramagnetic effect of melanin. Four of the five amelanotic melanomas had intermediate signal intensity on T1-weighted images; one was not detected. On T2-weighted images, all of the melanomas detected had intermediate though variable signal intensity compared with that of gray matter. On gadolinium-enhanced images, all cases demonstrated mild to moderate enhancement. The signal intensity of sinonasal melanoma appears to vary according to the histopathologic components of the tumor. High signal intensity within the lesion on T1-weighted images suggests the presence of melanin.

Aged↗
PubMedDate not supplied

Relationship between cerebral blood flow and clinical outcome in acute stroke.

OBJECTIVE: The purpose of this study was to determine the relationship between cerebral blood flow (CBF) measurements in acute stroke and early clinical outcome. MATERIAL AND METHODS: The xenon-enhanced computed tomography (XeCT) CBF studies performed in 50 patients in the acute stage (within 8 h) of a hemispheric stroke were retrospectively analyzed. The mean CBF of the symptomatic vascular territory was compared to the corresponding territory in the contralateral hemisphere. Clinical assessment on admission and discharge was performed using the National Institutes of Health stroke scale (NIHSS). RESULTS: Three groups were defined according to the degree of CBF asymmetry between the symptomatic and the contralateral asymptomatic vascular region. The CBF asymmetry was mild in group A (< or =20%), moderate in group B (>20% and <60%) and severe in group C (> or =60%). Patients in group A (n = 18) had a good outcome with a mean NIHSS score of 2 +/- 2 at discharge. In group B, the patients (n = 22) had intermediate but variable outcomes: 2 patients died and the mean NIHSS score for the survivors was variable (mean NIHSS score: 9 +/- 6). The patients in group C (n = 10) had a very poor outcome: 4 patients died and the survivors had a mean NIHSS score of 15 +/- 1. CONCLUSIONS: Quantitative XeCT CBF measurements may be useful for selecting subgroups of stroke patients with different clinical outcomes. The possibility of predicting patient prognosis as early as in the first hours after the ischemic event may help to identify the appropriate target population that will benefit from aggressive stroke therapy.

Acute Disease↗