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Biomedical subjects

S Todd

Publications and source records attributed to S Todd.

At least 73 records · Page 4Linked to original sources
PubMed1992

New chromosomal mapping assignments for argininosuccinate synthetase pseudogene 1, interferon-beta 3 gene, and the diazepam binding inhibitor gene.

Argininosuccinate synthetase pseudogene 1 (ASSP1), interferon-beta 3 (IFNB3) gene, and diazepam binding inhibitor (DBI) gene have previously been mapped to human chromosome 2. Their nucleotide sequences, recorded in the GENBANK data base, were used to generate DNA primers to amplify specific sequences using the polymerase chain reaction (PCR). These primers failed to amplify DNA sequences when used to analyze microcell hybrid clones containing human chromosome 2. In order to map these genes, a panel of somatic cell hybrids was analyzed by PCR with these primer sets. The results of these experiments place ASSP1 sequences on human chromosome 6, IFNB3 on human chromosome 8, and DBI on human chromosome 6.

Argininosuccinate Synthase↗
PubMed1992

Effects of peptide YY on the human cardiovascular system: reversal of responses to vasoactive intestinal peptide.

Peptide YY (PYY) reverses the increased intestinal secretion stimulated by vasoactive intestinal peptide (VIP) in humans. VIP also dilates blood vessels, so we investigated the effect of PYY on the cardiovascular system. Six volunteers received PYY, 0.4 and 1.2 pmol.kg-1 x min-1 i.v. for 2 h, reproducing plasma levels seen postprandially and during a diarrheal illness, respectively. Cardiac function was assessed by echocardiography. PYY infused at 0.4 pmol.kg-1 x min-1 had no effect on cardiovascular parameters. PYY infused at 1.2 pmol.kg-1 x min-1 caused a fall in both stroke volume from 128 +/- 8 to 110 +/- 8 ml/beat (mean +/- 95 confidence interval, P < 0.01) and cardiac output from 7.2 +/- 0.4 to 6.1 +/- 0.4 l/min (P < 0.01). Effects of infusion of PYY into the brachial artery at doses of 0-16 pmol/min were assessed using venous occlusion plethysmography in six subjects. PYY infusion caused a dose-dependent fall in forearm blood flow. Six subjects received VIP, 5 pmol.kg-1 x min-1 i.v., causing a rise in heart rate from 55 +/- 3 to 70 +/- 3 beats/min and increased cardiac output from 7.3 +/- 1.1 to 13.1 +/- 1.1 l/min. The addition of PYY, 0.4 pmol.kg-1 x min-1 i.v., did not affect the heart rate significantly but decreased the cardiac output to 10.4 +/- 1.1 l/min (P < 0.01). Infusions of PYY into the brachial artery at 5 pmol/min decreased local vasodilation induced by VIP infused at 2 pmol/min at the same site by 40% (P < 0.01), even though this dose of PYY had no significant effect on local blood flow when given alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

PCR primers for human chromosomes: reagents for the rapid analysis of somatic cell hybrids.

Rapid analysis of somatic cell hybrids can be facilitated by using the polymerase chain reaction (PCR) to assay for genes assigned to specific human chromosomes. We describe PCR primer pairs for genes on the short and long arms of the 22 autosomes and the X chromosome. Some of the primers were designed from the 3' untranslated region of cDNA sequences, whereas others were derived from genomic sequence. Each primer set was tested for its specificity and mapped to a chromosome by screening a somatic cell hybrid panel. Two of the primer pairs (APOC2 and G6PD) detect CA dinucleotide repeat polymorphisms.

Base Sequence↗
PubMed1990

Polysomnographic findings in adolescents with major depression.

Ten adolescents with major depression and 10 age-matched controls were studied with polysomnography for 3 consecutive nights. The sleep records were analyzed for variables pertaining to sleep continuity (total sleep time, sleep efficiency, sleep onset latency, number of awakenings, and number of stage shifts), sleep architecture (Stages 1, 2, 3, and 4), and rapid eye movement (REM) sleep (total) REM sleep time, number of REM periods, REM latency, and REM density). The experimental and control groups were compared on 14 variables with the t test for independent groups. The results indicated that none of the sleep variables differed significantly between the two groups. These results confirm earlier findings indicating that the abnormalities in REM latency and REM density that characterize adults with major depression are absent in adolescents suffering from major depression. Developmental and diagnostic variables are discussed as possible explanations for the sleep differences between adolescents and adults with depressive disorders.

Adolescent↗
PubMed1990

Evaluation of five methods for respiratory syncytial virus detection.

A total of 117 nasal aspirates were cultured for respiratory syncytial virus (RSV) and tested for RSV antigen by a direct fluorescent-antibody (DFA) test (Bartels Immunodiagnostic Supplies, Inc., Bellevue, Wash.), the Directigen enzyme immunoassay (EIA; Becton Dickinson Microbiology Systems, Cockeysville, Md.), the TestPack EIA (Abbott Laboratories, North Chicago, Ill.), and RSV EIA (Abbott). Agreement of two of five methods or a positive RSV culture were required to validate a result. A total of 57 of 117 (48.7%) specimens were culture positive in HEp-2 cells, A549 cells, or both. A total of 5 of 117 (4.3%) additional specimens met the criteria of a positive specimen; i.e., 62 of 117 (53.0%) specimens were positive. Results obtained from 77 of 117 (65.8%) specimens were concordant for all five methods. The sensitivities, specificities, and positive and negative predictive values for the culture and DFA methods were 91.9, 100, 100, and 91.7% and 91.9, 96.4, 96.6, and 91.4%, respectively. The sensitivities, specificities, and positive and negative predictive values for the three EIA procedures, Directigen, TestPack, and RSV EIA, were 75.8, 80.0, 81.0, and 74.6%; 93.6, 100, 100, and 93.2%; and 71.0, 100, 100, and 75.3%, respectively. New self-contained EIA configurations and the DFA method offer attractive alternatives to the culture method. Technical simplicity, rapid turnaround time, performance, and cost must all be considered when selecting a system for RSV detection.

Antigens, Viral↗
PubMed1989

Behavioral effects in the mouse during and following withdrawal from ethanol ingestion and/or nicotine administration.

The mechanism(s) by which ethanol or nicotine produces dependency and withdrawal symptoms during abstinence is poorly understood. In addition, it has been observed that a high correlation exists between ethanol intake and smoking. Therefore, studies were undertaken to evaluate aversion to the open arms of the elevated plus-maze and the modification of spontaneous locomotor activity during and following repeated ethanol and/or nicotine administration in mice. The ethanol plus nicotine treated animals increased time spent in the open arms of the maze during treatment relative to controls. Withdrawal from this combination treatment led to a rapid onset of intense aversion to the open arms of the maze and a concomitant reduction in locomotor activity which was greater than that produced by withdrawal from ethanol or nicotine treatment alone. The present results suggest that the combined effects of ethanol and nicotine reduced aversion to the open arms of the elevated plus-maze test system and may indicate an anti-aversive action. However, mice demonstrate an increased aversiveness to the open arms following sudden withdrawal of the combination treatment.

Animals↗
PubMed1989

cDNA sequence, interspecies comparison, and gene mapping analysis of argininosuccinate lyase.

A cDNA clone of the argininosuccinate lyase gene (ASL) was isolated from an adult human liver library by probing with synthetic oligonucleotide probes. This clone and a yeast genomic DNA fragment containing the ASL gene were sequenced using the M13-dideoxynucleotide method. Comparison of the yeast and human clones at the nucleotide and putative amino acid sequence levels indicated identities of 50 and 54%, respectively. The most conserved region of the yeast gene was used to detect human clones in the liver cDNA library to test phylogenetic screening capabilities of conserved genes. ASL was mapped to human chromosome 7pter----q22 using human-mouse somatic cell hybrid DNA and further mapped by in situ hybridization to chromosome 7cen----q11.2 on human metaphase chromosomes. The probe also detected a sequence on chromosome 22. Somatic cell hybrid DNA digested with PvuII revealed a mouse polymorphism between Balb/c and C3H mice in the ASL gene.

Amino Acid Sequence↗
PubMed1986

Mapping thyrotropin beta subunit gene in man and mouse.

Thyrotropin (TSH) is composed of two subunits: alpha and beta. Previously, we have mapped the TSH alpha gene to human chromosome 6 and mouse chromosome 4. In this study we have located the human TSH beta gene on chromosome 1 and the mouse TSH beta gene to chromosome 3. These data suggest that the TSH beta gene lies in a conserved linkage group with the genes for amylase 1 and 2, nerve growth factor, and the protooncogene Nras.

Animals↗
PubMed1985

Genes for insulin I and II, parathyroid hormone, and calcitonin are on rat chromosome 1.

Insulin, parathyroid hormone, and calcitonin are polypeptide hormones that regulate important physiological processes in target tissues. Rat genes encoding each hormone were chromosomally assigned to rat chromosome 1. Both rats and mice have two insulin genes (I and II). However, in contrast to mice in which insulin I and II are asyntenic, rat insulin I and II were both localized to chromosome 1. This study identifies a conserved syntenic group on rat chromosome 1, and implies that mouse insulin I and II genes were chromosomally separated after rats and mice diverged 20-35 million years ago.

Animals↗