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PubMed1990

Contraceptive behavior among sexually active Hispanic adolescents.

The purpose of this study was to examine those factors associated with the contraceptive behavior of a national representative sample of Hispanic female adolescents. The subjects included all (n = 85) unmarried, sexually active Hispanic women, aged 15 to 19, from the 1982 National Survey of Family Growth. Contraceptive behavior was measured on a normalized scale, ranging from oral contraceptives to no contraception. Mexican/American and Central/South American background females were more likely (p less than 0.031) to use effective birth control than Puerto Rican, Cuban, and other Hispanic background subjects. Twenty additional social, behavioral, and demographic variables were found to be significantly associated (p less than 0.05) with contraceptive behavior. Based on multiple regression analysis, seven of these variables were found to explain 62% (p less than 0.0001) of the variation in the contraceptive behavior of this sample. Poorer contraceptive behavior was associated with noncompliance with the initial birth control method used (33.8%), lower coital frequency (8.3%), older postmenarchial age (5.7%), failure to use birth control at first coitus (4.6%), fewer years dating (4.0%), lower frequency of church attendance (3.3%), and never having experienced a pregnancy scare (2.0%). These findings suggest that the contraceptive behavior of Hispanic female adolescents is a dynamic process that can be understood in the context of previous sexual and contraceptive behavior.

Adolescent↗

PubMed1979

Application of discriminant analysis to level of performance of alcoholics and nonalcoholics on Wechsler-Bellevue and Halstead-Reitan subtests.

Investigated the utility of subtests from the Wechsler-Bellevue Intelligence Scale and the Halstead-Reitan Neuropsychological Test Battery to differentiate between alcoholics and nonalcoholics (N = 76). Analyses of variance indicated that the alcoholics were more impaired than nonalcoholics. It was found that the Wechsler-Bellevue Performance subtests were more discriminative than were Verbal subtests, with performance on the Halstead-Reitan variables being intermediate. The nine measures that differentiated most significantly between groups were subjected to a stepwise multivariate discriminant analysis. The resulting function correctly classified Ss with an overall accuracy of 74.7%. It was found that the Block Design subtest was the best single discriminator. The findings were discussed in relationship to previous findings and with respect to general issues of clinical neuropsychological assessment.

Alcoholism↗

PubMed1995

Specific compositional patterns of synonymous positions in homologous mammalian genes.

All 69 homologous coding sequences that are currently available in four mammalian orders were aligned and the synonymous (ie., third) positions of quartet (fourfold degenerate) codons were divided into three classes (that will be called conserved, intermediate, and variable), according to whether they show no change, one change, and more than one change, respectively. The three classes were analyzed in their compositional patterns. In the majority of GC-rich genes, the three classes of positions (but especially conserved positions) exhibited significantly different base compositions compared to expectations based on a "random" substitution process from the "ancestral" (consensus) sequence to the present-day (actual) sequences. Significant differences were rare in GC-poor genes. An analysis of the present results indicates that natural selection plays a role in the synonymous nucleotide substitution process, especially in GC-rich genes which represent the vast majority of mammalian genes.

Animals↗

PubMed1977

Polymorphism of red cell glyoxalase 1. With special reference to South and Southeast Asia and Oceania.

Glyoxalase polymorphism has been studied in 7296 persons from populations in South Asia, Southeast Asia, Oceania, Iran and Colombia. The GLO frequencies are very low in most of Oceania, including Australia, somewhat higher in Southeast Asia, and intermediate though variable in India. In Iran the GLO frequency is similar to that in Europe. The value for the single amerindian group in Colombia is nearly 30%.

Asia, Southeastern↗

PubMed1987

Exercise training induces transitions of myosin isoform subunits within histochemically typed human muscle fibres.

Fibre type composition based on histochemical myosin ATPase reaction was studied in cross sections of biopsies from the vastus lateralis muscle of men. In addition, protein composition as well as peptide patterns of isolated myosin heavy chains were examined in batches of individually classified fibres from the same biopsies. High intensity endurance training during 8 weeks induces significant decreases by 31-70% of the type IIB fibre population in 3 of 4 subjects (in one case no change was observed). These decreases were offset by corresponding increases in either type I or type IIA fibres with the type IIC fibres remaining always below 3%. A total of 13 professional cyclists with training periods over several years have a 20 times lower content of type IIB fibres than 4 sedentary controls and a concomitant high content of 80% of type I fibres. The content of type I and type IIB fibres of 8 sprinter athletes did almost not differ from that of controls. Thus the type IIB fibres respond most sensitively with a decrease to aerobic endurance training. Since both type IIA and IIB fibres were identical in protein composition containing the same fast variety of myosin light chains and heavy chains as well as troponin-I, their interconversion could not be seen at the molecular level. However, the slow variety of myosin light chains and of troponin-I started accumulating after 8 weeks of training in type IIA fibres. Furthermore, the myosin heavy chain isoform started shifting by producing new peptide patterns that resemble the digestion pattern of slow myosin heavy chains in fibres which still classified as type IIA. These changes on the molecular level in type IIA fibres mark the beginning of their transition over the intermediate and variable type IIC fibres, towards the slow type I fibre.

Adult↗

PubMed1992

Correlations between densitometry of red-free photographs and reflectometry with the scanning laser ophthalmoscope in normal subjects and glaucoma patients.

OBJECTIVE: To compare image measurements of the retina produced by scanning laser ophthalmoscopy with those from red-free photographs (RFP) of the nerve fibre layer. SUBJECTS: The left eyes of 23 subjects (10 normal, 7 glaucoma suspect and 6 glaucomatous) were included in this study. METHOD: All the eyes were photographed using standard red-free photography, and images of the retina were digitised directly from the SLO. RESULTS: The correlation coefficient for all except three subjects was > 0.45, and the probability (p) that R = 0 was < 0.05 in all but 5 eyes. CONCLUSIONS: The data indicate that variations in retinal surface reflectivity as measured by the SLO are similar to those recorded on negative film during RFP. This further suggests that the SLO can be useful for making objective measurements of the RNFL, without the intermediate and variable steps of photography.

Densitometry↗

PubMed1994

Metabolic risk factors for atherosclerosis in heart transplant recipients.

Development of coronary artery disease (CAD) in the cardiac allograft limits long-term survival after heart transplantation. Previous studies, focusing on lipoprotein metabolism, have paid little attention to changes in glucose and insulin metabolism that increase the risk of CAD in these patients. To address this issue, plasma glucose and insulin responses to an oral glucose load and lipid and lipoprotein concentrations were measured in male normal volunteers (n = 40) and cardiac transplant recipients with pretransplant diagnoses of either idiopathic cardiomyopathy (n = 24) or ischemic heart disease (n = 28), matched for age and body mass index. Patients with a pretransplant diagnosis of ischemic heart disease had higher plasma glucose and insulin concentrations in response to oral glucose as well as higher fasting plasma triglyceride, cholesterol, and low-density lipoprotein cholesterol concentrations than did the control group (p < 0.005 to p < 0.001). In addition, high-density lipoprotein cholesterol concentrations were lower and the ratio of cholesterol to high-density lipoprotein cholesterol higher than control values in those with a pretransplant diagnosis of ischemic heart disease (p < 0.001). Values for almost all variables were intermediate in patients with a pretransplant diagnosis of idiopathic cardiomyopathy and in most instances were significantly different from both. Thus, male cardiac transplant recipients are dyslipidemic, relatively glucose intolerant, and hyperinsulinemic compared to normal volunteers. These changes, observed in patients with a pretransplant diagnosis of either ischemic heart disease or idiopathic cardiomyopathy, emphasize the important role of immunosuppression in the development of metabolic risk factors for CAD in these individuals.

Blood Glucose↗

PubMed1991

A new analysis of United Nations mortality statistics.

Demographic data published by the United Nations in 1987 are analysed in terms of the Gompertz function. Projections for maximum life spans are obtained, with the data broadly divisible into three clusters. These are attributable not only to the influence of high infant mortality, but suggest also constitutional and/or environmental variations among members of the clusters. The difference between life span and life expectancy is estimated analytically. A comparison with an earlier analysis supports the view that there are important differences between the life expectancies of the sexes.

Adult↗

PubMed1996

Epigenetic selection as a possible component of transdifferentiation. Further study of the commitment of hypertrophic chondrocytes to become osteocytes.

Transdifferentiation of hypertrophic chondrocytes into osteogenic cells was induced in 14 day chick embryo femurs by cutting through the region of hypertrophic cartilage. The process was studied in organ culture, using electron microscopy, staining for alkaline phosphatase, immunocytochemistry of collagen type I and proliferative cell nuclear antigen, and in situ localization of DNA strand-breaks. In addition, DNA and RNA synthesis were studied by 3[H]-T and 3[H]-U radioautography. Loss of ECM components from the cut edge occurred in culture. During the 12 day period necessary for transdifferentiation we observed phenotypic instability and bi-potentiality, the death of some cells and the gradual promotion of the osteoblastic phenotype in the survivors. Transition from chondrocytic to osteoblastic phenotype progressed stepwise, through variable mosaic intermediates, and involved a few cell cycles including asymmetric (differential) divisions. Proliferating and apoptotic cells were found in close proximity. As judged by the relative proportion of apoptotic cells and composition of the surrounding intralacunar matrix, negative selection of intermediate cell types displaying chondrocytic and altered mosaic phenotypes occurred. When the osteoblastic lineage was finally established, apoptotic cells were no longer present. Our hypothesis is that after disruption of cell-cell or cell-matrix interactions and lack of growth factors certain cells are selected and channelled through proliferation into the new stable phenotype. This process is targeted by the environment through a set of pre-determined steps.

Animals↗

PubMed1986