PubMed Health⌕ Search

Biomedical subjects

D E McMillan

Publications and source records attributed to D E McMillan.

At least 19 recordsLinked to original sources
PubMed1979

The effects of acetylmethadol on motor activity and schedule-controlled responding.

The effects of levo-alpha-acetylmethadol (LAAM) on locomotor activity and operant behavior were examined in rats. LAAM increased locomotor activity when given intraperitoneally (IP) at doses of 1 mg/kg and 3 mg/kg, but 10 mg/kg produced a slight decrease in motor activity over the 10-hour period. The largest increases and decreases in locomotor activity occurred 6--8 hours after administration of the drug. Other rats were trained to lever press for food pellets under a fixed-interval 90-second, fixed-ratio 10-response multiple schedule. LAAM only decreased rates of responding under the multiple schedule. Marked decreases in rates of responding under both components of the schedule occurred with LAAM was administered IP either 3 or 6 hours before the session at doses of 3 mg/kg and 10 mg/kg. The rate- decreasing effects of LAAM became greater the longer the interval between administration of the drug and initiation of the session.

Animals↗
PubMed1979

Effects of d-amphetamine and caffeine on schedule-controlled and schedule-induced responding.

The effects of d-amphetamine and caffeine were studied on rates and patterns of lever pressing and schedule-induced licking under fixed-interval schedules of food pellet presentation. In addition, the effects of caffeine were studied on lever pressing and licking under a multiple fixed-ratio fixed-interval schedule. Caffeine reduced mean overall rates of licking at lower doses than it reduced mean overall rates of pressing under the fixed-interval schedules, but the effects of caffeine on both licking and lever pressing depended largely on the control rate of responding. d-Amphetamine reduced mean overall rates of lever pressing and licking at about the same dose, but the effects of d-amphetamine also were a function of the control rate of responding.

Animals↗
PubMed1979

Performance and acquisition of serial position sequences by pigeons as measures of behavioral toxicity.

A procedure has been developed to measure the repeated acquisition of serial position sequences and to study the effects of drugs and toxic chemicals on the behavior generated by the procedure. Thus far experiments using the procedure have shown: (1) Performance schedules generate lower error rates than corresponding acquisition schedules: (2) Addition of a reset contingency further decreases errors under both performance and acquisition schedules: (3) Chained acquisition and performance schedules generate lower error rates than corresponding tandem acquisition and performance schedules: (4) Chained acquisition and performance schedules produce behavior that usually is more sensitive to drugs than corresponding tandem acquisition and performance schedules: (5) Acquisition schedules produce behavior that usually is more sensitive to drugs than corresponding performance schedules: and (6) Lead is an exception in that it produced clearer effects under a chained performance schedule with a reset contingency than under a corresponding acquisition schedule. The greater sensitivity to drug effects of behavior under acquisition schedules than behavior under performance schedules and of behavior under chained schedules may be a function of the baseline error rates, rather than the behavioral processes of acquisition, performance, and stimulus control.

Animals↗
PubMed1978

Combined effects of ethanol and diazepam on performance and acquisition of serial position sequences by pigeons.

The effects of diazepam and ethanol, alone and in combination, were studied in pigeons responding under acquisition and performance chain schedules. Both diazepam and ethanol increased the number of pecks on the incorrect key (errors). Under the acquisition schedule both diazepam and ethanol increased errors at doses lower than those under the performance schedule. Under both schedules effects of combinations of ethanol and diazepam were usually greater than the sum of the effects of the individual drugs.

Animals↗
PubMed1978

Mazindol effects on schedule-controlled responding of the pigeon.

The effects of mazindol, a non-phenethylamine anorexic, were determined in pigeons key pecking under a multiple fixed-ratio 30 response, fixed-interval 5 min schedule of food presentation. The low average rates of responding under the fixed-interval schedule were greatly increased (from 0.7 response/sec to 2 responses/sec) at doses from 0.1 to 10 mg/kg. The higher rates of responding under the fixed-ratio schedule were only decreased by increasing doses of mazindol. Throughout the fixed interval, mazindol tended to produce a constant rate of responding completely disrupting the normal, positively accelerated pattern of responding. These rate-increasing effects of mazindol were much greater than those of phenethylamines tested under similar conditions. The large increases in rates of responding under the fixed-interval component were discussed in terms of the known biochemical effects of mazindol.

Animals↗
PubMed1978

Diabetic angiopathy--its lessons in vascular physiology.

Progress in our understanding diabetic angiopathy has been slow, but we are now learning a number of lessons of interest to the cardiologist. Diabetic angiopathy is a collective term for conditions specific to the diabetic state and related to its duration more than to patient age. The angiopathy produces calcification of the media of larger arteries, but its major effects are in the microcirculation. Intense interest in one feature, skeletal muscle capillary basement membrane thickening, has dominated the last decade. Capillary basement membrane thickening, while characteristic of diabetes, is associated with little direct impairment of the microcirculatin. It appears to play no role in the pathogenesis of diabetes itself. The pathology of diabetic retinopathy and diabetic nephropathy suggests that arteriolar changes may be the major mediator of diabetic angiopathy. This concept is supported by the interactions between hypertension and diabetes in the eye and kidney. The course of diabetes of youthful onset differs from that of maturity onset. The relative frequency of diabetic angiopathy is higher, and of atherosclerotic complications is lower. This has made it difficult to demonstrate the potential value of preventive measures. Benefit to one type of problem may become hidden by worsening of the other. If the diabetic benefits from what is learned about how ischemic heart disease risk can be reduced, he will require even more effective management to prevent or control diabetic angiopathy.

Arteriosclerosis↗
PubMed1978

Food, water and ethanol consumption by rats under a fixed-interval schedule of food presentation.

Rats could lever press 24 hours a day for 97 mg food pellets under a fixed-interval (FI) 90 second schedule. During the first 4 days, an ethanol solution was the only available fluid, after which both water and ethanol solutions were available. At ethanol concentrations (w/v) of 5%, 7.5% and l0%, total caloric intake and total fluid intake remained constant, while ethanol consumption was inversely proportional to the concentration of the solution. When the FI 90s schedule was changed to FI 45 s, or to FI 180 s, there were only small changes in total caloric intake, total fluid intake and in percentages of total fluid consumption and total caloric intake as ethanol. The data suggest that the intake of ethanol under this fixed-interval schedule depends more on the ethanol concentration than on the calories obtained from ethanol drinking.

Alcohol Drinking↗
PubMed1978

Effects of lead on temporally-spaced responding in rats.

The effects of lead acetate and aging on temporally-spaced responding (differential reinforcement of low rate or DRL-20 seconds) were studied. Three groups of animals were considered along with their respective controls. Neonate-treated Long-Evans rats were orally intubated with 200 mg/kg lead acetate from the third to 30th day after birth. Some of these animals were tested at 3 months (adult group) and some at 21 months (geriatric group) of age. A continuously treated group was exposed to 250 ppm lead in utero and throughout their life after birth and was treated at 8 months of age. Lead-treated animals exhibited a more variable response to d-amphetamine and a more pronounced number of IRTs in the first class interval. Aging shifted the pentobarbital dose-response curve to the left in both control and lead-treated animals and flattened interresponse time (IRT) distributions.

Aging↗
PubMed1978

Chronic chlordiazepoxide and pentobarbital interactions on punished and unpunished behavior.

Dose-effect curves were determined in rats for the effects of drugs on punished and unpunished responding maintained by fixed-interval schedules of food presentation before, during and after the drinking of large daily doses of chlordiazepoxide and pentobarbital. An average intake of 50 mg/kg/day of chlordiazepoxide produced tolerance to the rate-decreasing effects of chlordiazepoxide on unpunished responding and cross-tolerance to the rate-decreasing effects of pentobarbital. During chlordiazepoxide drinking, rate-increasing effects of both chlordiazepoxide and pentobarbital on punished responding became apparent. There was no evidence for cross-tolerance between chlordiazepoxide and chlorpromazine. An average intake of 100 mg/kg/day of pentobarbital produced similar evidence of tolerance to the rate-decreasing effects of pentobarbital on unpunished responding and cross-tolerance to the rate-decreasing effects of chlordiazepoxide. Removal of chlordiazepoxide from the drinking water temporarily increased unpunished responding; however, 6 weeks after withdrawal of chlordiazepoxide or pentobarbital from the drinking water, the dose-effect curves for injections of these drugs appeared to be returning to their original positions.

Animals↗