Search PubMed⌕ Search

Biomedical subjects

C J Meliska

Publications and source records attributed to C J Meliska.

30 records · Page 2Linked to original sources
PubMed1984

Effects of caffeine use and ingestion on a protracted visual vigilance task.

College students (12 female, 12 male) were assigned to either higher caffeine user (HCU) or lower caffeine user (LCU) groups based on a caffeine usage survey. Prior to testing, subjects ingested either placebo or 195 or 325 mg caffeine. They then performed a visual vigilance task measuring response blocks, discrete responses (hits and false alarms), reaction times, and a Mood Check List using a double-blind design. HCU made significantly fewer hits, more false alarms, and also responded faster than LCU. No significant main effects of caffeine administration were found. In the mood analyses, male subjects were more anxious at the end of the experiment. Overall, the user factor (HCU versus LCU) was the most potent experimental variable.

Adolescent↗
PubMed1984

Caffeine and nicotine: differential effects on ambulation, rearing and wheelrunning.

Male Sprague Dawley rats were tested for open field ambulation and rearing, and for wheelrunning, following repeated injections of either caffeine or nicotine, given according to a Latin Square design. Caffeine enhanced ambulation and rearing at 5 and 15 mg/kg, IP, and increased wheelrunning with 15 and 45 mg/kg. Nicotine (0.63 mg/kg) also enhanced ambulation, but not rearing, and depressed wheelrunning during the first 20 min of testing. Caffeine's enhancement of wheelrunning was not significant during the first two drug administrations. Results suggest that caffeine and nicotine affect activity via different neuropharmacological mechanisms. Previous experience with these drugs may modulate animals' reactivity to them.

Animals↗
PubMed1980

The effects of ketamine enantiomers on schedule-controlled behavior in the rat.

Male Sprague-Dawley rats were trained to barpress under a FL-300 sec schedule of food presentation until responding patterns were stable. The effects of the ketamine optical isomers (enantioners) on this schedule-controlled behavior were examined over a dose range of 3.75 to 60 mg/kg i.p. At doses of 15 mg/kg and above, (-)-ketamine increased rate of responding, with a maximum increase of about 3 times control rate. This effect was rate-dependent, being more marked at lower control rates. In contrast (+)-ketamine did not increase overall fixed-interval response rate at any dose, but decreased rate of responding in a rate-dependent fashion at doses of 30 mg/kg and above. Spontaneous locomotor activity was increased about equally by equimolar doses of both enantiomers.

Animals↗
PubMed1978

Differential effects of ketamine on schedule-controlled responding and motility.

Male Sprague-Dawley reats were trained to bar press for food reinforcement on an FI-300 sec schedule. Ketamine (7.5 mg/kg, IP) significantly increased response rates of both drug-naive and drug-experienced rats for the first 10 min after injection. With a 15.0 mg/kg dose of ketamine, response rates decreased significantly during the first 10 min after injection, irrespective of prior drug experience, but increased significantly above control thereafter in drug-experienced animals. Both doses of ketamine enhanced spontaneous locomotor activity significantly, irrespective of prior drug experience. Differences in the time course and dose dependency of these effects suggest that ketamine stimulates schedule-controlled responding and spontaneous locomotor activity via different neuropharmacologic mechanisms.

Animals↗
PubMedDate not supplied

Nicotine patches improve mood and response speed in a lexical decision task.

The effects of smoking a cigarette or wearing a transdermal nicotine patch on mood and lexical decision-making were tested in eight smokers. Each participant was tested after 4 hours of smoking abstinence, under 4 conditions: placebo (very low nicotine) cigarette, nicotine cigarette, placebo patch, and nicotine patch. Relative to placebo, wearing the nicotine patch reduced Profile of Mood States (POMS) Total Mood Disturbance and Fatigue/Inertia scores, while increasing the speed of some types of lexical decisions. Smoking a nicotine cigarette did not affect reaction times, but unexpectedly decreased the accuracy of Word/ Nonword lexical decisions. Thus, transdermal nicotine may improve mood and facilitate longterm memory search and/or attentional processes in nicotine-deprived smokers.

Administration, Cutaneous↗
PubMedDate not supplied

Copulatory behavior and fertility in transgenic male mice expressing human placental growth hormone gene.

Male transgenic (TG) mice overexpressing the human placental growth hormone (GH) variant gene (hGH-V) exhibit reproductive deficits in spite of normal testosterone levels and normal sperm counts. To evaluate the relationship of copulatory behaviors to fertility, we first measured mount, intromission, and ejaculation indices in 2-5-month-old mice (10 TG and 10 normal litter mate controls) during 1 hour tests with ovariectomized, estrogen-, and progesterone-primed females. After eight tests, each male was housed with three intact females for 27 consecutive days. Females were checked daily for vaginal plugs and sacrificed 14 days after insemination to determine the numbers of corpora lutea and live and dead fetuses. Relative to their normal siblings, TG mice mounted less often and intromitted sooner after the initial mount, made marginally more intromissions (with and without ejaculation), and were slower to ejaculate. In subsequent fertility tests, TG males inseminated fewer females and sired fewer live fetuses per insemination than non-TG controls. Across TG and normal males, the length of interval between initial mount and initial intromission was inversely correlated with the number of live offspring sired. This suggests that reduced fertility in hGH-V transgenic male mice may be related to altered copulatory behavior, including a rapid progression from first mount to first intromission.

Animals↗