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Biomedical subjects

A Mays

Publications and source records attributed to A Mays.

8 recordsLinked to original sources
PubMed2001

A streamlined process to phenotypically profile heterologous cDNAs in parallel using yeast cell-based assays.

To meet the demands of developing lead drugs for the profusion of human genes being sequenced as part of the human genome project, we developed a high-throughput assay construction method in yeast. A set of optimized techniques allows us to rapidly transfer large numbers of heterologous cDNAs from nonyeast plasmids into yeast expression vectors. These high- or low-copy yeast expression plasmids are then converted quickly into integration-competent vectors for phenotypic profiling of the heterologous gene products. The process was validated first by testing proteins of diverse function, such as p38, poly(ADP-ribose) polymerase-1, and PI 3-kinase, by making active-site mutations and using existing small molecule inhibitors of these proteins. For less well-characterized genes, a novel random mutagenesis scheme was developed that allows a combination selection/screen for mutations that retain full-length expression and yet reverse a growth phenotype in yeast. A broad range of proteins in different functional classes has been profiled, with an average yield for growth interference phenotypes of approximately 30%. The ease of manipulation of the yeast genome affords us the opportunity to approach drug discovery and exploratory biology on a genomic scale and shortens assay development time significantly.

Amino Acid Sequence↗
PubMed2000

Environmental control of stomatal conductance in forest trees of the Great Smoky Mountains National Park.

To determine if stomatal conductance (g(s)) of forest trees could be predicted from measures of leaf microclimate, diurnal variability in in situ g(s) was measured in black cherry (Prunus serotina), red maple (Acer rubrum), and northern red oak (Quercus rubra). Relative to overstory trees, understory saplings exhibited little diurnal variability in g(s) and ozone uptake. Depending on species and site, up to 30% of diurnal and seasonal variation in g(s )of overstory trees was explained by photosynthetically active radiation and vapor pressure deficit. Daily maximum g(s) was significantly related to soil moisture in overstory northern red oak and black cherry (R(2) ranged from 33 to 65%). Although g(s) was not fully predicted using instantaneous measures of leaf microclimate, ozone uptake of large forest trees was reduced by low soil moisture.

Journal Article↗
PubMed1994

Isobutyramide, an orally bioavailable butyrate analogue, stimulates fetal globin gene expression in vitro and in vivo.

Butyrate and other short-chain fatty acids stimulate fetal globin gene expression and have potential for ameliorating the beta globin disorders. Butyrate, however, is rapidly metabolized in vivo and reaches only micromolar concentrations in plasma. We report here that a branched-chain derivative of butyrate, isobutyramide, increases gamma globin gene expression in cultured human erythroid progenitors in vitro and stimulates activity from a minimal gamma globin gene promoter linked to a reporter gene in stable and transient expression assays, with slightly less activity in these in vitro assays than butyrate. In vivo, administration of isobutyramide to anaemic adult baboons rapidly stimulates fetal globin synthesis and F-reticulocyte production. Plasma concentrations at millimolar levels are achieved after a single intravenous or oral dose (500-600 mg/kg), and these concentrations are maintained for 9.5-10.5 h. These results indicate that although isobutyramide has slightly less activity than butyrate in vitro in enhancing fetal globin expression at the cellular and molecular level, its prolonged in vivo half-life may provide superior activity as a therapeutic agent for reactivating fetal globin gene expression in vivo.

Administration, Oral↗
PubMed1992

Fetal hemoglobin levels in sickle cell disease and normal individuals are partially controlled by an X-linked gene located at Xp22.2.

Fetal hemoglobin (Hb F) production in sickle cell (SS) disease and in normal individuals varies over a 20-fold range and is under genetic control. Previous studies suggested that variant Hb F levels might be controlled by genetic loci separate from the beta-globin complex on chromosome 11. Using microscopic radial immunodiffusion and flow cytometric immunofluorescent assays to determine the percentage of F reticulocytes and F cells in SS and nonanemic individuals, we observed that F-cell levels were significantly higher in nonanemic females than males (mean +/- SD, 3.8% +/- 3.2% v 2.7% +/- 2.3%). F-cell production as determined by F reticulocyte levels in SS females was also higher than in SS males (17% +/- 10% v 13% +/- 8%). We tested the hypothesis that F-cell production in both normal and anemic SS individuals was controlled by an X-linked locus with two alleles, high (H) and low (L). Using an algorithm to determine the 99.8% confidence interval of a normal distribution in nonanemic individuals, we estimated that males and females with at least one H allele had greater than 3.3% F cells. Comparisons of male-male or female-female SS sib pairs with discordant F reticulocyte levels distinguished two phenotypes in SS males (L, less than 12%; H, greater than 12%) and three phenotypes in SS females (LL, less than 12%; HL, 12% to 24%, HH greater than 24%). Linkage analysis using polymorphic restriction sites along the X chromosome in eight SS and one AA family localized the F-cell production (FCP) locus to Xp22.2, with a maximum lod score (logarithm of odds of linkage v independent assortment) of 4.6 at a recombination fraction of 0.04.

Adult↗
PubMedDate not supplied

Augmenting surgery for sensory esotropia with near/distance disparity with a medial rectus posterior fixation suture.

Ten esotropic patients with near/distance disparity and diminished vision in one eye had monocular horizontal strabismus surgery combined with a posterior fixation suture placed on the medial rectus. Before surgery, all patients were at least 20 prism diopters (delta) more esotropic at near than at distance fixation. The disparity in the near/distance deviation was reduced by 18 delta.

Adolescent↗