Past research suggests an apparent paradox: Women who engage in same-gender sexual behavior show higher rates of unintended pregnancy than women with exclusive other-gender sexual behavior. Such women also have disproportionate rates of early adversity (both harshness, such as abuse or neglect, and unpredictability, such as father absence). We used the Add Health data (N?=?5,617 cisgender women) to examine the relative contributions of early adversity, adolescent same-gender sexual behavior, and general sexual risk behavior to women’s risks for adult unintended pregnancy. Women who engaged in adolescent same-gender sexual behavior were more likely to report childhood adversity, and both childhood adversity and adolescent same-gender behavior made independent contributions to subsequent rates of unintended pregnancy. The association between adolescent same-gender sexual behavior and adult unintended pregnancy was partially attributable to the fact that women with adolescent same-gender sexual behavior engaged in greater sexual risk behavior more broadly. These findings suggest that same-gender sexual behavior in adolescence may relate to a broader set of sexual risk behaviors that augment future risk for unintended pregnancy, independent of sexual identity. We draw on life history theory to explain this pattern of results and suggest directions for future research.
The metabolic derangements of pregnancies complicated by diabetesmellitus, specifically hyperglycaemia and hyper-ketonaemia,are known to be teratogenic during the period of organogenesisin animals. We have shown previously that poorly controled diabetesmellitus impairs in-vivo and in-vitro mouse preimplantationembryo growth, and that culturing embryos in elevated glucoseconcentrations only partially recreated this developmental dealy.To extend this observation we examined the effect on mouse preimplantationembryo growth of elevated concentrations of other metabolicintermediates, which may be deranged in diabetes mellitys, namelylipids, lactate, glycerol, amino acids, and ketones. Two-cellembryos from ovulation-induced B6C3F1 mice were cultured for72 h in the presence of added lipids (250 mg/dl), lactate (5mM), glycerol (160 µM) or mixed amino acids (8.5% travosol,7 mM) and showed no significant difference in growth over 72h verus their control groups. However, growth of preimplantationembryos in acetoacetate (10 mM) or in the racemic micture ofDL--hydroxybutyrate (16 and 32mM) revealed marked retardationversus controls when assessed either by distribution of developmentalstages over time (24, 48, 72 h, P <0.001) or by the differencein the average rank of sums indicating a delay in maturation(P<0.0001). We conclude that elevated ketone concentrationsadversely affect preimplantation embryo development. These findingsextend previous studies which correlate uncontrolled diabetesmellitus as well as hyperglycaemia with abnormal organogenesis,and demonstrate tht exposure to metabolic derangements may alsohinder reproductive performane at even earlier stages in gestation. 相似文献
Very-long-baseline interferometry images of the nuclear region of the radio galaxy Cygnus A reveal a pronounced "core" and a knotty jet and counterjet. The knots are moving away from the core at apparent speeds which are subluminal for h = 1 [h = H0/100 km.s-1.Mpc-1;1 parsec (pc) = 3.09 x 10(16)m] and about c for h = 0.5. The jet is aligned with the outer, kiloparsec-scale jet to within 2 degrees. The counterjet has a total flux density at 5 GHz of about one-fifth of that of the jet. In the context of the twin relativistic jet model for active galactic nuclei, the jet in Cygnus A is oriented at an angle to our line of sight of 35-80 degrees and 55-85 degrees, and the intrinsic velocity of the jet fluid is 0.4-0.6c and 0.6-1c for h = 1 and h = 0.5, respectively. 相似文献
Significant advances were reported this year in the identification of the chromosomal location of mutated genes on the 13 and 6 chromosomes which cause forms of autosomal dominant Stargardt's macular dystrophy. Observations in monozygotic twins with age-related macular dystrophy were described. Mitochondrial DNA mutations in Cubans with optic and peripheral neuropathy were reported. A new autosomal dominant proximal myotonic myopathy was described. Persistence of the tunica vasculosa lentis was suggested as a helpful sign of congenital myotonic dystrophy. The panoply of ocular findings in acromesomelic dysplasia were presented. Genetic characterization of the ocular findings in Duchenne type and Becker's muscular dystrophy was reported. Finally, a new syndrome of autosomal dominant cerebellar ataxia with retinal degeneration was described. 相似文献
Summary The recognition of recurring sites of chromosome changes in malignancies has greatly facilitated the identification of genes implicated in the pathogenesis of human cancers. Based especially upon recent studies [1–4], it appears increasingly likely that a subset of recurring chromosome alterations will be recognized in human breast cancer. Currently recognized chromosome changes characterizing breast carcinoma include the recognition of cytologic features of gene amplification (e.g. double minutes [dmins] and homogeneously staining regions [HSRs]) [5–8]. As these and other chromosome regions are implicated in recurring abnormalities in breast cancer, it will become increasingly important to have band-or region-specific genomic libraries and probes in order to facilitate high resolution physical mapping and ultimately to clone breast cancer related genes [9]. Toward this end an important recent development in physical mapping has been the establishment of chromosome microdissection as a rapid and reproducible approach to rapidly isolate and characterize chromosome region-specific DNA, greatly facilitating the initial steps in positional cloning of disease-related genes [10–13]. In this brief report, we will highlight the application of chromosome microdissection to the generation of region-specific probes for both fluorescent in situ hybridization (FISH) and the generation of genomic microclone libraries. Additionally, efforts using this methodology to generate a microclone library encompassing the early onset breast/ovarian cancer (BRCA1) gene will be presented.Presented by Jeffrey M. Trent at the 16th Annual San Antonio Breast Cancer Symposium, San Antonio TX, USA, November 4, 1993; Minisymposium on Molecular Genetics in Breast Cancer. 相似文献