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Biomedical subjects

M Vaughan

Publications and source records attributed to M Vaughan.

294 records · Page 17Linked to original sources
PubMedDate not supplied

Subspecific affinity of black bears in the White River National Wildlife Refuge.

The black bear population of the White River National Wildlife Refuge (NWR) is adjacent to populations of black bear in Louisiana (Urusus americanus luteolus) which are listed as threatened under the U.S. Endangered Species Act. Wildlife management plans can pose restrictions on bear harvests and timber extraction; therefore the management plan for the White River NWR is sensitive to subspecific classification of its bear population. The objective of this study was to analyze genetic variation in the White River NWR and seven adjacent populations of black bears to assess the subspecific affinity of the White River NWR population. Here we report the variation at seven microsatellite DNA loci among eight black bear populations. The patterns of genetic variation gave strong support for distinguishing a southern group of black bears comprised of the White River, Arkansas; Tensas River, Louisiana; Upper Atchafalaya, Louisiana; Lower Atchafalaya, Louisiana; and Alabama/Mississippi populations. Phylogenetic analysis of individual variation suggested that historical black bear introductions into Arkansas and Louisiana affected gene pools of certain southern receiving populations, but did not significantly change interpopulation relatedness. Phylogenetic inferences at both the population and individual levels support the hypothesis that the White River NWR population of black bears belongs to the U. a. luteolus subspecies.

Alleles↗
PubMedDate not supplied

Cardiovascular and neuroendocrine responses to extended laboratory challenge.

The purpose of this study was to examine the effects of a 2-hour laboratory challenge on heart rate, blood pressure, catecholamines, and cortisol; and investigate the contribution of the physical act of speaking on both neuroendocrine and cardiovascular measures. Using a within-subjects design, 14 subjects were tested individually during two separate laboratory sessions. During one session, subjects engaged in two cognitively demanding tasks for 2 hours. During the other session, subjects executed the verbal demands of the tasks for 2 hours, but cognitive demands were absent. During both sessions, blood pressure and heart rate were measured and arterialized blood samples were obtained for the measurement of epinephrine, norepinephrine, and cortisol. Subjects demonstrated significantly greater increases in systolic blood pressure diastolic blood pressure, heart rate, epinephrine, and cortisol during the cognitively challenging session than during the control session. It is concluded that sustained elevations in cardiovascular and neuroendocrine measures can be achieved in the laboratory, and that the effects of such tasks cannot be attributed solely to the physical demands of speaking. Implications for the measurement of circulating catecholamines and cortisol during laboratory studies are discussed.

Adult↗
PubMedDate not supplied

Acute psychological stress and epinephrine infusion in normolipidemic and hyperlipidemic men: effects on plasma lipid and apoprotein concentrations.

This study examined whether psychological stress and the infusion of epinephrine increase plasma lipid and apoprotein concentrations in normolipidemic and hyperlipidemic men. Subjects were studied during three separate 6-hour laboratory sessions: a control session, during which subjects rested quietly while blood samples and hemodynamic measurements were obtained; a stress session, during which subjects were presented with two challenging mental tasks, followed by quiet rest; and an epinephrine infusion session, during which subjects received a low-dose infusion of epinephrine followed by quiet rest. The stress and epinephrine infusion manipulations produced the expected changes in plasma epinephrine and norepinephrine levels, blood pressure, and heart rate. Free fatty acid concentration increased markedly during epinephrine infusion and less dramatically but consistently during mental stress. Both stress and epinephrine infusion produced acute increases in plasma total, low-density lipoprotein, very low-density lipoprotein, and high-density lipoprotein cholesterol and apoprotein B concentrations, but comparable increases during the control session were not observed. Changes in albumin concentration (an index of plasma volume) were associated with changes in lipid concentrations during psychological stress. Epinephrine increases during psychological stress were correlated with increases in free fatty acid and triglyceride levels both during and after task administration. It was concluded that psychological or pharmacological stress induced in the laboratory produces changes in lipid concentrations, which at least during psychological stress, may be attributed to concomitant changes in plasma volume. The association between task-induced changes in epinephrine and changes in free fatty acid and triglyceride levels, also supports the hypothesis that psychological stress increases lipolysis.

Adult↗