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Biomedical subjects

D Layman

Publications and source records attributed to D Layman.

9 recordsLinked to original sources
PubMed2001

Complete genome sequence of Salmonella enterica serovar Typhimurium LT2.

Salmonella enterica subspecies I, serovar Typhimurium (S. typhimurium), is a leading cause of human gastroenteritis, and is used as a mouse model of human typhoid fever. The incidence of non-typhoid salmonellosis is increasing worldwide, causing millions of infections and many deaths in the human population each year. Here we sequenced the 4,857-kilobase (kb) chromosome and 94-kb virulence plasmid of S. typhimurium strain LT2. The distribution of close homologues of S. typhimurium LT2 genes in eight related enterobacteria was determined using previously completed genomes of three related bacteria, sample sequencing of both S. enterica serovar Paratyphi A (S. paratyphi A) and Klebsiella pneumoniae, and hybridization of three unsequenced genomes to a microarray of S. typhimurium LT2 genes. Lateral transfer of genes is frequent, with 11% of the S. typhimurium LT2 genes missing from S. enterica serovar Typhi (S. typhi), and 29% missing from Escherichia coli K12. The 352 gene homologues of S. typhimurium LT2 confined to subspecies I of S. enterica-containing most mammalian and bird pathogens-are useful for studies of epidemiology, host specificity and pathogenesis. Most of these homologues were previously unknown, and 50 may be exported to the periplasm or outer membrane, rendering them accessible as therapeutic or vaccine targets.

Animals↗
PubMed1983

Interaction between glucose and dehydroascorbate transport in human neutrophils and fibroblasts.

Dehydroascorbate (DHA) competitively inhibits the uptake of 2-deoxy-D-glucose and of 3-O-methyl-D-glucose by human blood neutrophils; 2-deoxyglucose and 3-O-methylglucose competitively inhibit dehydroascorbate uptake. Ratios of Km to Kl are near unity for each of these ligands. Exposure of cultured human fibroblasts to insulin enhances cytochalasin B-inhibitable uptake of DHA and of 2-deoxyglucose, both to the same degree. These observations suggest that DHA transport is mediated by glucose transport systems in human neutrophils and fibroblasts.

3-O-Methylglucose↗
PubMed1981

Human cell dehydroascorbate reductase. Kinetic and functional properties.

Dehydroascorbate reductase (glutathione: dehydroascorbate oxidoreductase, EC 1.8.5.1) activity was examined in crude cytosol extracts of human cells. In blood neutrophil and lymphocyte extracts, the Km at pH 6.85 for dehydroascorbate was 1.3 mM, and for reduced glutathione 3.8 mM. Rates of dehydroascorbate uptake by intact human neutrophils, monocytes, lymphocytes and cultured fibroblasts were proportional to cytosol dehydroascorbate reductase activities. Dehydroascorbate reduction during dehydroascorbate uptake by these cells may be entirely enzymatic.

Cells, Cultured↗
PubMed1975

A behavioral-educational alternative to drug control of hyperactive children.

A behavioral procedure for controlling hyperactivity without inhibiting academic performance is described. Using a time-sample observational method, the hyperactivity displayed by three school children was recorded during math and reading classes. Concurrently, math and reading performances were measured. The study consisted of two baselines, one while the children were on medication and the second while they were off medication. A multiple-baseline design across the two academic subject matters was used to assess the behavioral intervention, which consisted of token reinforcement for correct academic responses in math and subsequently math and reading. Discontinuation of medication resulted in a gross increase in hyperactivity from 20% to about 80%, and a slight increase in math and reading performance. Introduction of a behavioral program for academic performance, during no medication, controlled the children's hyperactivity at a level comparable to that when they were on drugs (about 20%). At the same time, math and reading performance for the group jumped from about 12% during baseline to a level of over 85% correct. Each child performed behaviorally and academically in an optimal manner without medication. Contingency management techniques provided a feasible alternative to medication for controlling hyperactivity in the classroom while enabling the children to grow academically.

Achievement↗