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Biomedical subjects

D G Gilbert

Publications and source records attributed to D G Gilbert.

11 recordsLinked to original sources
PubMed1992

Subjective correlates of cigarette-smoking-induced elevations of peripheral beta-endorphin and cortisol.

Two experiments assessed subjective and hormonal effects of smoking cigarettes with three different nicotine deliveries. In experiment 1, 12 males smoked two cigarettes on three different occasions: (1) nicotine-free; (2) their own brand (1.0 mg FTC-estimated nicotine delivery); or (3) 2.4 mg FTC nicotine cigarettes. In experiment 2, 12 males smoked cigarettes of comparable nicotine yield using a quantified smoke delivery system (QSDS). Blood was sampled 2 min after each cigarette completion. Relative to nicotine-free smoking, plasma beta-endorphin (BE) and serum cortisol concentrations increased after quasi-ad libitum smoking of 2.4 mg, but not after 1.0 mg nicotine cigarettes. Self-reported malaise (nausea, sickness, and unpleasantness) also increased after smoking 2.4 mg nicotine cigarettes; subjective distress was correlated with changes in blood BE and cortisol. Smoking 1.0 mg cigarettes did not increase BE or cortisol, or subjective distress. QSDS smoking produced hormonal and subjective effects similar to quasi-ad libitum smoking; however, correlations between neuromodulator concentrations and mood were non-significant. These findings suggest that the elevated levels of plasma BE and cortisol reported in some smoking studies may not be characteristic effects of normal smoking.

Adult↗
PubMed1991

Hormonal and subjective effects of smoking the first five cigarettes of the day: a comparison in males and females.

The effects of smoking normal-nicotine-delivery cigarettes on serum cortisol, plasma beta-endorphin (BE), and mood were measured in 8 male and 8 female smokers; 8 male and 8 female nonsmokers served as sham-smoking controls. Smoking five cigarettes of the smokers' usual type after overnight deprivation, either ad lib or via a quantified smoke delivery system, produced small but reliable elevations in serum cortisol concentrations; BE was elevated somewhat after two, but not after four or five cigarettes. Smoking-induced elevations in serum cortisol were correlated with decreases in self-reported drowsiness after two and five cigarettes. Additionally, female smokers reported more drowsiness at baseline and after smoking nicotine-free cigarettes than did male smokers or female nonsmokers. Results suggest that smoking-induced elevations in serum cortisol, which persist for at least the first five cigarettes of the day, may modulate the arousing effects of smoking under conditions of low arousal. Also, nicotine-deprived female smokers may experience subnormal arousal compared to male smokers or female nonsmokers.

Adult↗
PubMed1990

Cardiovascular responses to a quantified dose of nicotine as a function of personality and nicotine tolerance.

Correlations between cardiovascular effects of a quantified dose of nicotine and personality measures previously shown to predict coronary heart disease were obtained. Thirty male smokers smoked a popular brand of a regular strength cigarette (1.0 mg FTC-estimated nicotine delivery) on one occasion and a nicotine-free cigarette on another occasion by means of a quantified smoke delivery system. Partial correlations controlling for effects of body weight, questionnaire-assessed nicotine tolerance, and cardiovascular responses to the nicotine-free control cigarette showed Jenkins Activity Survey Type A scores to correlate positively with nicotine-induced increase in diastolic blood pressure but negatively with nicotine-induced increase in systolic blood pressure. Partial correlations indicated that trait anxiety and depression were significantly associated with nicotine-induced heart rate increases but not with nicotine-induced blood pressure responses.

Adult↗
PubMed1990

Characterization of a dose-response curve for nicotine-induced conditioned taste aversion in rats: relationship to elevation of plasma beta-endorphin concentration.

In the first experiment a conditioned taste aversion paradigm was used to characterize a dose-response curve for the aversive properties of nicotine in male Sprague-Dawley rats. Doses of nicotine ranging from 0.01 to 0.46 mg/kg, 2.0 ml of 0.47 M lithium chloride, or saline were injected, ip, 10 min after exposure to a novel saccharin solution. Amount of saccharin consumed in a two-bottle test was assessed 72 h later. Nicotine doses of 0.046 mg/kg and above produced a significant degree of conditioned taste aversion. In a second experiment, four groups of 10 rats each were injected with saline, 0.022 mg/kg nicotine, 0.46 mg/kg nicotine, or 2.0 ml 0.47 of M LiCl. Doses of 0.46 mg/kg nicotine and 0.47 M LiCl elevated plasma beta-endorphin concentrations significantly above saline control values. The 0.022 mg/kg dose, the highest dose that did not produce conditioned taste aversion in Experiment 1, did not significantly increase plasma beta-endorphin concentrations. This finding suggests that doses of nicotine that produce conditioned taste aversion also promote the release of pituitary stress hormones. Taken together these data suggest that some of the pharmacological and behavioral effects attributed to nicotine, including the release of endogenous neuromodulators, may be dose-dependent concomitants of the aversive effects of nicotine in nicotine-naive animals.

Animals↗
PubMed1990

Two Hypercard calculators for molecular biology.

Two calculators built in Macintosh Hypercard are described. GelFragSizer estimates and plots DNA restriction fragment sizes, using the local reciprocal or cubic spline methods. Enzyme Kinetics estimates the Michaelis-Menton rate parameters for enzyme-catalyzed reactions, and plots data versus estimated curve in a variety of formats. These stacks help to demonstrate the ease and sophistication of calculation tools that scientists can develop with Hypercard.

Computer Graphics↗
PubMed1989

Effects of smoking/nicotine on anxiety, heart rate, and lateralization of EEG during a stressful movie.

The effects of smoking cigarettes with differing FTC nicotine deliveries on anxiety and EEG activity were evaluated in 40 smokers who were compared with 40 non-smokers, matched for age and gender. Following smoking (sham-smoking in the case of the non-smokers), the participants viewed a stress-inducing movie. Smoking higher-nicotine delivery cigarettes during the movie, as compared to smoking low-nicotine control cigarettes, was associated with reductions in anxiety and right hemisphere activation, increased heart rate, and enhancement of the ratio of left-hemisphere parietal EEG activation to right-hemisphere activation. These results are interpreted as indicating that the anxiolytic effects of nicotine may be mediated by the right hemisphere. The EEG activity and emotional responses of non-smokers were more like those of smokers who smoked the lower-nicotine cigarettes than those of smokers of the higher-nicotine cigarettes.

Adult↗
PubMed1988

A system for administering quantified doses of tobacco smoke to human subjects: plasma nicotine and filter pad validation.

A new, automated system for administering quantified doses of cigarette smoke to human subjects is described and results of two studies demonstrating the reliability and validity of the system are presented. To overcome the large variability in nicotine and tar delivery associated with previous means of controlling smoke delivery, an automated quantified smoke delivery system was constructed. The system increases the precision and reliability of the smoke and nicotine dose delivered to human subjects. The quantified smoke delivery system was found to deliver doses of nicotine with a substantially greater degree of precision than procedures typically used in previous laboratory studies of smoking behavior.

Administration, Inhalation↗
PubMed1987

Effects of smoking on heart rate, anxiety, and feelings of success during social interaction.

The effects of smoking on heart rate (HR) and emotional processes during social interactions were assessed in 12 smokers. Smoking was associated with less anxiety and with enhanced feelings of being successful both in changing the opinions of others and in expressing one's own point of view. These findings are consistent with others in the literature. The increase in HR during social interactions in which the participants smoked was similar in magnitude to the HR increase associated with speaking versus listening during conversation. The effects of smoking and social interaction on HR appeared to be additive. Smoking during the social interaction increased HR only about half as much as is typically reported for smokers seated quietly in nonsocial situations.

Adaptation, Psychological↗
PubMed1977

Maternal mortality in Michigan: an epidemiologic analysis, 1950-1971.

An analysis was performed of direct maternal mortality over 22 years (1950 through 1971) in the state of Michigan. The overall direct maternal mortality rate fell from 5.0/10,000 live births in 1950 to 1.5 in 1971. The rate among nonwhites was more than four times greater than among whites and the difference in relative risk did not narrow over the 22 years. Mortality rates increased with increasing maternal age but not with increasing parity. Nulliparous women had a significantly higher mortality rate than did parous women, particularly those over 25 years of age. when the white gravida of urban Wayne County were compared with the white gravida of 33 rural counties, no difference in direct maternal mortality rates could be attributed to rurality per se. Hemorrhage, infection, and toxemia were the leading causes of direct maternal death. The data suggest that hospitals with less active obstetrical services were associated with a higher risk of direct maternal mortality than were hospitals whose obstetrical services were more active. An increasing proportion of the direct maternal deaths was designated as preventable over the study period. It is believed that analyses of maternal mortality have led to improved perinatal and obstetrical care and that further advances require their continued support. (Am. J. Public Health 67:821-829, 1977)

Abortion, Spontaneous↗