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Biomedical subjects

I Greenberg

Publications and source records attributed to I Greenberg.

At least 37 records · Page 2Linked to original sources
PubMed1978

Experimental analysis of the 'happy hour": effects of purchase price on alcohol consumption.

An experimental analogue of a discount drink policy known as the "happy hour" was used to study the effects of purchase price on drinking behavior. Male volunteers with a prior history of either casual (N=20) or heavy (N=14) drinking were given free access to beverage alcohol during a 20-day period. Approximately half the subjects could purchase alcohol under a single-price condition (50 cents/drink), while a matched group was given a price reduction daily (25 cents/drink) during a three-hour period in the afternoon. The results demonstrated that the afternoon price reduction significantly increased alcohol consumption in both casual and heavy drinkers. Reinstatement of the standard purchase price effectively suppressed drinking in both groups. The findings are discussed in terms of the theoretical and research implications of environmental influences on drinking.

Adult↗
PubMed1978

Nerve extract induces increase and redistribution of acetylcholine receptors on cloned muscle cells.

The effect of rat spinal cord explants and cell-free nerve extract on acetylcholine receptor site density and distribution was studied using (125)I- and rhodamine-labeled alpha-bungarotoxin on L(6), a cloned rat muscle cell line. Control L(6) myotubes have a low and uniform distribution of acetylcholine receptors (20 +/- 3 sites per mum(2) in the present study). The addition of spinal cord explants caused an increase in average receptor site density of about 6 times on myotubes within 2 mm of the explant, while a smaller increase of 3 times was observed at distances greater than 5 mm. The formation of high-density patches of receptors was also stimulated. These observations suggested that a diffusible substance originating from the explant was responsible for these changes. Cell-free homogenates of the central nervous system were prepared and found to produce the same effects. The effect of the homogenate was not strongly dependent on the age of the fetus from which the tissue was isolated, and fetal liver had little or no effect. The active component(s) appears to be a protein(s) with a molecular weight of about 100,000. Because the nerve homogenates make the L(6) cells resemble primary muscle cultures, we suggest that a common factor is responsible for regulating the acetylcholine receptor in the two types of muscle culture. The normally acetylcholine receptor-poor L(6) cells may provide a more sensitive assay for these factors than do primary muscle cultures.

Acetylcholine↗
PubMed1978

Multidisciplinary approach to adult obesity therapy.

A comprehensive program has been designed to treat medically significant obesity (body mass index greater than 30). The essential components include nutritional education, exercise, mental conditioning, relaxation and assertiveness training. Adherence to this combined program is supported by rapid weight loss utilizing a protein-sparing modified fast. Initial efforts include greater than 18 kg (40 lb) weight loss in three out of four patients and greater than two years maintenance in one out of three patients. The varying success depends on patient adherence to a prolonged education program at least six months to one year directed at modification of lifestyle. Both for lasting safety and effectiveness a professional partnership is required between the physician and patient. Finally the result of therapy appears to be rehabilitation and not cure from the problem of obesity.

Avoidance Learning↗
PubMed1976

Effects of marihuana use on body weight and caloric intake in humans.

Body weight and caloric intake were measured in a group of heavy and casual marihuana users prior to, during and following 21 days of marihuana smoking under research ward conditions. A group of control subjects were studied under identical conditions, but they did not smoke marihuana. Both heavy and casual marihuana users had a significant increase in caloric intake and gained weight during the marihuana smoking period. Heavy and casual users gained an average of 3.7 and 2.8 lbs respectively during the first 5 days of marihuana smoking. In contrast, control subjects gained only a small amount of weight (0.2 lbs) during the same time interval. Water retention did not appear to be a major factor in weight gain by the marihuana users. These findings are in agreement with both anecdotal reports and previous experimental data that marihuana use is associated with increased caloric intake and weight gain.

Body Weight↗
PubMed1976

Stimulus properties of the narcotic antagonist pentazocine: similarity to morphine and antagonism by naloxone.

Pentazocine (10 mg/kg) and saline were used as discriminative stimuli in rats. After pentazocine administration, reinforcement could be obtained contingent on pressing one particular lever (left or right) in a two-lever operant chamber. Responding on the opposite lever was reinforced only after saline injections; a drug-lever combination was always held constant for each animal. Discriminated choice responding between pentazocine and saline was learned to an 80% correct criterion. Test injections of morphine produced dose-related responding on the pentazocine lever. Choice responding after 7.5 mg/kg of morphine was not significantly different from choice responding after 10 mg/kg of pentazocine. The discriminable ED50 values for both pentazocine and morphine were estimated from dose-response curves and when given in combination (pentazocine ED50 + morphine ED50), more drug-related responding occurred than occurred after either drug (ED50) alone. Naloxone produced saline-like responding but antagonized the stimulus properties of both pentazocine and morphine. However, the antagonism of the morphine cue by naloxone was significantly greater than the antagonism of the pentazocine cue. The results indicate that pentazocine and morphine are similar in at least one important respect suggesting that these drugs may share a common site of action.

Animals↗
PubMed1976

Pharmacy exhibits in medical staff education.

The use of hospital pharmacy exhibits as a means of educating physicians about pharmacy services and improving physician-pharmacist relationships is discussed. Two exhibits concerning potassium supplementation and total parenteral nutrition are described.

Audiovisual Aids↗
PubMed1976

Operant acquisition of marihuana in man.

Operant work for marihuana cigarettes or money and the effects of marihuana smoking on behavior were examined in 12 casual and 15 heavy marihuana users. Male volunteers were studied in groups of four on a clinical research ward and each subject served as his own control. A 5-day base-line period was followed by a 21-day marihuana available period and a 5-day postmarihuana control period. Subjects could earn one 1-g marihuana cigarette or 50 cents by 30 minutes of sustained performance on a simple operant task. All casual and most heavy user subjects gradually increased marihuana smoking through time. The heavy users smoked more (4.3-6 cigarettes/day) than the casual users (2-3/day). Both groups worked between 2 and 5 times as many hours per day as was necessary to earn the number of cigarettes smoked. Consequently, subjects earned and saved far more money than was spent for marihuana. The heaviest smokers worked between 6.7 and 14.4 hours/day, every day. Periods of maximal work coincided with periods of maximal smoking, i.e., between 4 P.M. and 12 midnight each day. Delayed effects of marihuana dose on points earned the following day showed a dose-related decrement in operant work output. In the heavy user group, operant performance decreased sharply 24 hours after 3 ciagrettes/day were smoked, then remained relatively stable after 3 to 8 cigarettes daily and decreased further on the few occasions when more than 8 cigarettes were smoked. In the casual user group, the largest 24-hour delayed changes in performance occurred after the smoking of between 1 and 2 and 3 and 4 marihuana cigarettes. No subject stopped operant work even when he smoked 10 or more marihuana cigarettes per day. These data do not support the hypothesis that marihuana induces an "amotivational" syndrome.

Adult↗
PubMed1975

Behaviorally induced sensitivity to the discriminable properties of LSD.

Rats were initially trained to discriminate LSD from saline in two-lever operant chambers by reinforcing responses only on one lever following intraperitoneal injections of 80 mug/kg of LSD and only on the other lever following saline injections. Choice responding during extinction periods (no water reinforcement for either response) indicated a high level of discriminability (95% correct) following either LSD or saline. A dose-response curve for LSD, obtained by tests for lever choice after injections of 10, 20, 30, 40, 50, and 60 mug/kg, indicated that 10 mug/kg produced only 30% responding on the LSD lever. This percentage was increased (to 83%) by reinforcing responding on the LSD lever following injections of 10 mug/kg. Subsequent tests indicated that doses of 5.0 and 2.5 mug/kg produced a majority of responses on the LSD lever. Since at these low doses LSD has few measurable biochemical or behavioral effects, we hypothesized that the discriminable cue of LSD is related to direct stimulation of central serotonergic receptors.

Animals↗
PubMed1975

Marijuana consumption and tolerance to physiological and subjective effects.

The relation between marijuana consumption and the development of tolerance was investigated during a 31-day study. Volunteers with a history of moderate or heavy marijuana use were given access to one-gram (2.1% delta9 tetrahydrocannabinol [THC]) marijuana cigarettes during a 21-day smoking period. Both groups tended to increase consumption during this time. Heavy users averaged 5.7 cigarettes per day and indicated a progressive decline in ratings of intoxication and duration of pulse rate effect. Moderate users averaged 3.2 cigarettes per day but showed no changes in either of these reactions during this time. Results suggested that tolerance does not develop to the two most reliable indexes of marijuana intoxication unless heavy doses of delta9 THC are self-administered repeatedly. Also, the tendency to increase consumption during this time is not necessarily associated with the development of tolerance.

Adult↗