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Biomedical subjects

M Billingsley

Publications and source records attributed to M Billingsley.

18 recordsLinked to original sources
PubMed1991

Elevated plasma platelet-derived growth factor B-chain levels in cancer patients.

Platelet-derived growth factor (PDGF) is produced by a variety of normal and tumor cells in vitro. We have developed an enzyme-linked immunosorbent assay for the detection of the B-chain of PDGF. This assay can reliably detect 0.1 ng/ml of homodimeric recombinant PDGF B-chain and does not cross-react with recombinant PDGF-AA, epidermal growth factor, basic fibroblast growth factor, or transforming growth factor-beta. Citrated plasma from 72 control individuals had a PDGF B-chain (PDGF-B) level of 0.32 +/- 0.14 ng/ml (mean +/- SD) with a range of 0.10-0.69 ng/ml. The plasma platelet factor 4 (PF4) level was 97 +/- 70 ng/ml, with a range of 34-363 ng/ml. Citrated plasma was obtained from 131 cancer patients, and plasma PDGF-B was elevated in 19 (15%) of the patients. Both PDGF-B and PF4 were elevated in 14 (11%) of these patients, consistent with a platelet source of PDGF-B. In 5 patients (4%), however, PDGF-B was elevated and PF4 was not elevated compared to the control group. This last group of patients may have a tumor-derived source of PDGF-B which could be important in autocrine or paracrine growth stimulation of the tumor cells.

Adult↗
PubMed1991

Cherry: who are you?

Do we need a new role model to inspire today's teenagers to look at nursing as a career? If so, who and what should this character be? Billingsley offers her ideas.

Career Choice↗
PubMed1991

Automation and us.

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Attitude of Health Personnel↗
PubMed1989

The identification of a novel synaptosomal-associated protein, SNAP-25, differentially expressed by neuronal subpopulations.

cDNA clones of a neuronal-specific mRNA encoding a novel 25-kD synaptosomal protein, SNAP-25, that is widely, but differentially expressed by diverse neuronal subpopulations of the mammalian nervous system have been isolated and characterized. The sequence of the SNAP-25 cDNA revealed a single open reading frame that encodes a primary translation product of 206 amino acids. Antisera elicited against a 12-amino acid peptide, corresponding to the carboxy-terminal residues of the predicted polypeptide sequence, recognized a single 25-kD protein that is associated with synaptosomal fractions of hippocampal preparations. The SNAP-25 polypeptide remains associated with synaptosomal membrane components after hypoosmotic lysis and is released by nonionic detergent but not high salt extraction. Although the SNAP-25 polypeptide lacks a hydrophobic stretch of residues compatible with a transmembrane region, the amino terminus may form an amphiphilic helix that may facilitate alignment with membranes. The predicted amino acid sequence also includes a cluster of four closely spaced cysteine residues, similar to the metal binding domains of some metalloproteins, suggesting that the SNAP-25 polypeptide may have the potential to coordinately bind metal ions. Consistent with the protein fractionation, light and electron microscopic immunocytochemistry indicated that SNAP-25 is located within the presynaptic terminals of hippocampal mossy fibers and the inner molecular layer of the dentate gyrus. The mRNA was found to be enriched within neurons of the neocortex, hippocampus, piriform cortex, anterior thalamic nuclei, pontine nuclei, and granule cells of the cerebellum. The distribution of the SNAP-25 mRNA and the association of the protein with presynaptic elements suggest that SNAP-25 may play an important role in the synaptic function of specific neuronal systems.

Amino Acid Sequence↗
PubMed1988

Lessons, Part I.

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Humans↗
PubMed1979

Effects of picrotoxin, naloxone, and vagotomy on chlordiazepoxide-induced respiratory depression.

Intravenous administration of chlordiazepoxide (CDP) caused respiratory depression in both rats and cats. The maximally tolerated dose of CDP was found to be 165 +/- 15 mg/kg, i.v., in rats. Pretreatment with picrotoxin (1.5 mg/kg) or naloxone (20 mg/kg, i.v.) significantly increased the maximally tolerated dose of CDP to 330 +/- 40 mg/kg, i.v., and 270 +/- 35 mg/kg, i.v., respectively. The protective effects of both naloxone and picrotoxin were absent in bilaterally vagotomized rats. Naloxone pretreatment (25 mg/kg, i.v.) was also found to block the respiratory depressant effects of CDP in anesthetized cats, but had no effect on the cardiovascular actions of CDP. It is possible that the respiratory effects of CDP are due to its actions on GABA receptors, and that peripheral GABA receptors may mediate the protective actions of picrotoxin and naloxone.

Animals↗