"Sexual differentiation: From genes to gender"

Amy Wisniewski is Assistant Professor of Biology at Drake University, Des Moines, Iowa. She can be contacted at [email protected] person's sex can be considered across various levels. To illustrate, genes, hormones, and genitalia can all be considered physical markers of a person's sex. In addition to physical markers, behaviors such as gender role, gender identity and sexual orientation can be perceived as stereotypically male or female. The purpose of this review is to summarize current knowledge of sexual differentiation which emphasizes genetic and hormonal mechanisms that result in male and female development of gonads and genitalia. Finally, consideration is given to associations between genetic sex, gonadal sex, and hormonal sex with gender. Copyright 1998 S Karger AG

Phenotypic Heterogeneity Within Clones Of Fetal Human Cells

The heterogeneity of cell morphology characteristics of some colonies of human fetal kidney and amniotic fluid cells has been analyzed by biochemical and cell-cloning techniques. All the presumed subclones derived from dimorphic colonies were initially epithelioid, but some cells became fibroblastlike as the cell density increased. To determine if the observed heterogeneity occurred within clonal populations of cells, we determined the isozyme phenotype of dimers from renal cells heterozygous for glucose-6-phosphate dehydrogenase (G6PD). Colonies showing mixed cellular morphology expressed only a single G6PD isozyme, thus revealing their single-cell origin. Our results indicate that cell morphology is influenced by the cellular density within the clone, and that a single human renal cell in vitro can yield progeny of two morphological types

Adaptive smoothing for enhancing images

We present a new filter for image enhancement belonging to the family of the Edge Preserving Smoothing Filtering (EPSF). The proposed filter comes from a recent clustering method based on information theory and statistical mechanics developed by YE Wong [191. Its effect is to attenuate noise by smoothing the image within homogeneous regions while it enhances the contrast at their boundaries as anisotropic diffusion filters do . However, this filter performs a more continuous smoothing than anisotropic diffusion filtering which usually produce piecewise constant surfaces. Actually, we show that it is related to a multi-scale anisotropic diffusion process.Cet article présente un nouveau filtre de prétraitement d'image, de la famille des filtres EPSF («Edge Preserving Smoothing Filters »). Il est dérivé d'une récente méthode de classification, basée sur la théorie de l'information et la mécanique statistique, développée par Y.F. Wong [19]. Il permet d' atténuer le bruit en opérant un très bon lissage intra-région, tout en rehaussant les bords flous entre les régions, comme le font les filtres basés sur le principe de la diffusion anisotrope. En revanche, contrairement à ces derniers qui ont pour inconvénient de tendre à produire des surfaces constantes par morceaux, il offre une continuité de lissage très intéressante. Par ailleurs, on montre également que ce filtre est lié à un processus de diffusion anisotrope multi-échelle

Normal sex differences in prenatal growth and abnormal prenatal growth retardation associated with 46,XY disorders of sex development are absent in newborns with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

<p>Abstract</p> <p>Background</p> <p>Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is the most common presentation of a disorder of sex development (DSD) in genetic females. A report of prenatal growth retardation in cases of 46,XY DSD, coupled with observations of below-optimal final height in both males and females with congenital adrenal hyperplasia due to 21-hydroxylase deficiency, prompted us to investigate prenatal growth in the latter group. Additionally, because girls with congenital adrenal hyperplasia are exposed to increased levels of androgens in the absence of a male sex-chromosome complement, the presence or absence of typical sex differences in growth of newborns would support or refute a hormonal explanation for these differences.</p> <p>Methods</p> <p>In total, 105 newborns with congenital adrenal hyperplasia were identified in our database. Gestational age (weeks), birth weight (kg), birth length (cm) and parental heights (cm) were obtained. Mid-parental height was considered in the analyses.</p> <p>Results</p> <p>Mean birth weight percentile for congenital adrenal hyperplasia was 49.26%, indicating no evidence of a difference in birth weight from the expected standard population median of 50th percentile (<it>P </it>> 0.05). The expected sex difference in favor of heavier males was not seen (<it>P </it>> 0.05). Of the 105 subjects, 44 (27%; 34 females, 10 males) had birth length and gestational age recorded in their medical chart. Mean birth length for this subgroup was 50.90 cm (63rd percentile), which differed from the expected standard population median of 50th percentile (<it>P </it>= 0.0082). The expected sex difference in favor of longer males was also not seen (<it>P </it>> 0.05).</p> <p>Conclusion</p> <p>The prenatal growth retardation patterns reported in cases of 46,XY disorders of sex development do not generalize to people with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Sex differences in body weight and length typically seen in young infants were not seen in the subjects who participated in this study. We speculate that these differences were ameliorated in this study because of increased levels of prenatal androgens experienced by the females infants.</p

Effect of various dopant elements on primary graphite growth

Five spheroidal graphite cast irons were investigated, a usual ferritic grade and four pearlitic alloys containing Cu and doped with Sb, Sn and Ti. These alloys were remelted in a graphite crucible, leading to volatilization of the magnesium added for spheroidization and to carbon saturation of the liquid. The alloys were then cooled down and maintained at a temperature above the eutectic temperature. During this step, primary graphite could develop showing various features depending on the doping elements added. The largest effects were that of Ti which greatly reduces graphite nucleation and growth, and that of Sb which leads to rounded agglomerates instead of lamellar graphite. The samples have been investigated with secondary ion mass spectrometry to enlighten distribution of elements in primary graphite. SIMS analysis showed almost even distribution of elements, including Mg and Al (from the inoculant) in the ferritic grade, while uneven distribution was evident in all doped alloys. Investigations are going on to clarify if the uneven distribution is associated with structural defects in the graphite precipitates

CHARACTERISTICS OF THE INCREASED ADRENOCORTICAL FUNCTION OBSERVED IN MANY OBESE PATIENTS *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75360/1/j.1749-6632.1965.tb34805.x.pd

Variability of Sequence Surrounding the Xist Gene in Rodents Suggests Taxon-Specific Regulation of X Chromosome Inactivation

One of the two X chromosomes in female mammalian cells is subject to inactivation (XCI) initiated by the Xist gene. In this study, we examined in rodents (voles and rat) the conservation of the microsatellite region DXPas34, the Tsix gene (antisense counterpart of Xist), and enhancer Xite that have been shown to flank Xist and regulate XCI in mouse. We have found that mouse regions of the Tsix gene major promoter and minisatellite repeat DXPas34 are conserved among rodents. We have also shown that in voles and rat the region homologous to the mouse Tsix major promoter, initiates antisense to Xist transcription and terminates around the Xist gene start site as is observed with mouse Tsix. A conservation of Tsix expression pattern in voles, rat and mice suggests a crucial role of the antisense transcription in regulation of Xist and XIC in rodents. Most surprisingly, we have found that voles lack the regions homologous to the regulatory element Xite, which is instead replaced with the Slc7a3 gene that is unassociated with the X-inactivation centre in any other eutherians studied. Furthermore, we have not identified any transcription that could have the same functions as murine Xite in voles. Overall, our data show that not all the functional elements surrounding Xist in mice are well conserved even within rodents, thereby suggesting that the regulation of XCI may be at least partially taxon-specific