Biomedical subjects
M Billingsley
Publications and source records attributed to M Billingsley.
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.
Automation and us.
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The importance of followers.
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The student practicum: 1990.
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We've met the expert ... and it's us!
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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.
The needed perspective.
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Where is the grass roots?
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I want to be a nurse (c. 1965)
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The review process: navigating the system.
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Carboxylmethylation of phosphodiesterase attenuates its activation by ca2+-calmodulin.
Carboxylmethylation of several preparations of cAMP phosphodiesterase by the enzyme protein O- carboxylmethyltransferase and S-adenosylmethionine reduces the extent to which the enzyme was activated by native calmodulin. In contrast, carboxylmethylation of calmodulin produced only a slight reduction in the ability of calmodulin to activate cAMP phosphodiesterase. The effect of carboxylmethylation of calmodulin was most prominent at subsaturating calmodulin concentrations, whereas the reduction in the activation of carboxylmethylated cAMP phosphodiesterase was independent of calmodulin concentration. Kinetics and stoichiometric analysis of calmodulin carboxylmethylation indicated that less than 5% of calmodulin was methylated and that the Km of protein O- carboxylmethyltransferase for calmodulin was approximately 350 microM. The extent of calmodulin carboxylmethylation was not affected by either EGTA or Ca2+. When homogeneous bovine brain phosphodiesterase was carboxylmethylated , a rapid decrease in calmodulin-induced stimulation was noted, occurring within 30 s of incubation. Acidic sodium dodecyl sulfate-gel electrophoresis of bovine brain phosphodiesterase revealed a major band of 60,000 daltons which contained radio-activity after carboxylmethylation . Stoichiometric analysis revealed that approximately 20% of the phosphodiesterase was carboxylmethylated . Thus, although calmodulin can serve as a substrate for carboxylmethylation , it appears that carboxylmethylation has a greater effect on calmodulin-dependent phosphodiesterase activity when the target enzyme, rather than calmodulin, is carboxylmethylated .
Role of calmodulin in the regulation of dopamine receptor function.
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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.
Reengineering the corporate culture of hospitals.
As we move closer to the turn of the century, the American health care system continues to provide management experts with a wealth of case studies describing the winners and losers in today's business environment. Winners in this cost-conscious era of institutional reengineering, said Senge in his best-selling book The Fifth Discipline (1990), are those organizations that bind together around a common identity, a sense of destiny, and a shared commitment to reconciling the existing threats to their survival. Senge suggests that the organizations that are able to tap people's commitment and capacity to learn at all levels of the structure will overcome the type of maladaptation to business threats so commonly seen in corporate failures today.