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Biomedical subjects

R W Foltin

Publications and source records attributed to R W Foltin.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effect of amphetamine on human macronutrient intake.

Six male subjects participated in a 15-day residential study examining the effects of amphetamine on macronutrient intake. During the first 11 days, carbohydrate intake was manipulated by providing lunch meals high (155 g) or low (25 g) in carbohydrate. Subjects received oral d-amphetamine (5, 10 mg/70 kg, BID) or placebo. Total daily caloric intake was similar under both lunch conditions (approximately 3400/Kcal), but carbohydrate contributed more energy under the high-carbohydrate condition. Both doses of amphetamine decreased total caloric intake to approximately 2600 Kcal, by decreasing the number of eating bouts, without affecting macronutrient selection. During the last four days subjects received a higher daily dose of amphetamine (30 mg/70 kg in four doses) or placebo, and were allowed to self-select lunch. Although 30 mg amphetamine decreased intake of all macronutrients, the relative contribution of carbohydrate to total caloric intake was increased from 54% to 62%, while the contribution of fat was decreased from 32% to 26% and the contribution of protein was decreased from 14% to 12%. Thus, at a high dose, amphetamine altered the relative contribution of specific macronutrients to total caloric intake.

Adult↗
PubMed1995

Cardiovascular effects of cocaine in humans: laboratory studies.

Studies in which healthy, carefully screened, experienced cocaine users receive cocaine under controlled laboratory conditions, although often overlooked by the medical community, are an excellent source of data on the cardiovascular effects of cocaine. Cocaine is generally self-administered in repeated-dose 'binges', and studies simulating this pattern provide interesting cardiovascular information, such as the selective development of acute tolerance or the unique effects of some drug combinations. Studies with intranasal, intravenous, and smoked cocaine all show that under conditions in which subjects are allowed to take cocaine repeatedly, heart rate generally returns to near baseline levels between doses despite gradually increasing cocaine blood levels. Blood pressure either shows the same pattern, or gradual increases with repeated dosing. Analyses of cardiovascular activity as a function of cocaine plasma level indicate the rapid development of acute (i.e., within session) tolerance to cocaine. Cocaine self-administration often occurs in the presence of behavioral stressors, or in combination with other drugs of abuse or cocaine abuse treatment medications. Performance of a behaviorally-demanding task increases heart rate and blood pressure. When cocaine is taken prior to task performance larger increases in heart rate are observed than with either drug or task alone. An unexpected cardiovascular interaction was observed in subjects who inhaled cocaine and drank ethanol-containing beverages. This combination resulted in heart rate increases that were significantly larger than observed with either drug alone. Combinations of i.v. cocaine and smoked marijuana also increased heart rate above levels seen with either drug alone. A single intravenous dose of cocaine and morphine in combination, however, produced cardiovascular effects similar to those produced by cocaine alone. The effects of these drug combinations on blood pressure were often equal to the effect of one drug alone. Since cocaine is frequently taken in combination with potential treatment drugs, these interactions can be assessed under controlled settings prior to large-scale treatment studies. For instance, maintenance on the antidepressant desipramine increased baseline heart rate and diastolic pressure. Cocaine administration engendered increases in heart rate and blood pressure above the desipramine-elevated baselines. Clearly, drug interactions can have unexpected cardiovascular effects, and laboratory studies provide a controlled setting for understanding and studying these interactions.

Alcohol Drinking↗
PubMed1995

Effects of single and multiple intravenous cocaine injections in humans maintained on methadone.

The effects of i.v. cocaine were examined in individuals maintained on methadone. Sixteen adult methadone-maintained i.v. cocaine users, residing on a clinical research unit, participated in eight laboratory sessions under each of two conditions: cocaine 1 hr after daily methadone and cocaine 22 hr after daily methadone. The conditions were separated by an outpatient period of 3 to 5 weeks. During the first five sessions, the cardiovascular and subjective effects of single i.v. cocaine doses (0, 8, 16, 32 or 48 mg/70 kg) were determined. During the last three sessions, the effects of i.v. cocaine (0, 8 or 32 mg/70 kg) administered 4 times per session at 14-min intervals were determined. Single and repeated doses of cocaine produced dose-dependent increases in cardiovascular effects (e.g., diastolic pressure and heart rate), subjective effects (e.g., ratings of "High," or "Stimulated") and ratings of cocaine dose (e.g., "Quality," or "Liking"), regardless of methadone dose or the timing of cocaine administration. Increases in blood pressure after single cocaine doses were greater when cocaine was given 1 hr after methadone. Subjects maintained on higher methadone doses (> 60 mg) reported larger cocaine effects after single doses on several measures including ratings of Liking and Stimulated. Finally, the opiate symptom scores after cocaine administration were 100% larger than those observed previously after cocaine administration to opiate-experienced, but not dependent, individuals. These data suggest that any improvement in cocaine abuse observed in methadone-maintained individuals is not related to a blocking of the subjective effects of cocaine, and that higher methadone doses could have a negative impact on cocaine abuse in some individuals.

Adult↗
PubMed1994

Effect of meal macronutrient and energy content on human performance.

The effects of planned meals, varying in carbohydrate (CHO), fat and caloric content, on psychomotor performance by male subjects with unrestricted access to commercially-available foods was investigated in two residential studies. In the first study, two groups of three subjects (n = 6) completed psychomotor tasks before and after consuming a lunch consisting of 431 or 844 kcal, with caloric differences produced through covert changes in either fat or CHO content. The effects of each of four lunch conditions (low-fat, high-fat, low-CHO, high-CHO) were determined for three consecutive days. In the second study, two groups of three subjects (n = 6) received breakfast, lunch and an afternoon snack and completed psychomotor tasks after breakfast and lunch. Cumulative caloric content of the three eating occasions was approximately 700, 1200 or 1700 kcal (low, medium or high), again with differences resulting from covert changes primarily in either fat or CHO content. The effects of each of six food conditions were determined for two consecutive days. While changes in some aspects of performance were altered after meals, the effects were not related to the CHO, fat or caloric content of the meal. When subjects have unrestricted access to commercially-available foods, neither calories nor the relative fat or CHO content of normal meals influence human psychomotor task performance.

Adult↗
PubMed1994

Effects of delta 9-tetrahydrocannabinol and social context on marijuana self-administration by humans.

The effects of time of day and social context on daily patterns of marijuana self-administration were examined in two groups of three adult male marijuana smokers during a 12-day residential study. Days were divided into 6.5-h work and social-access periods. Order of occurrence (i.e., work before social access or social access before work) was counterbalanced between groups and reversed for both groups on day 8. Up to eight marijuana cigarettes (0.0% or 2.3% delta 9-THC) could be smoked each day. Stable patterns of marijuana smoking were observed across days for each subject. Three subjects smoked more marijuana during the social-access period, regardless of when it occurred. The other three smoked more marijuana during the first period, regardless of whether it was a work or social-access period. The number of marijuana cigarettes smoked was unrelated to THC content. In contrast, subjective reports of "High," "Liking," "Potency" and "Drug" on visual-analog scales were increased on active marijuana days. Subjective reports of drug effects were not predictive of drug self-administration.

Adult↗
PubMed1994

Satiety after preloads with different amounts of fat and carbohydrate: implications for obesity.

High intake of dietary fat may be key in both the etiology and maintenance of obesity. Because a reduction in the proportion of energy derived from fat will be accompanied by an increase in the proportion of energy derived from carbohydrate, this study compared the effects of these macronutrients on eating behavior in obese and lean individuals. The effects of different amounts of fat and carbohydrate, covertly incorporated into yogurt preloads, on subsequent food intake, hunger, and satiety were assessed. A group of 12 normal-weight men, unconcerned about eating and body weight (unrestrained), accurately compensated for the energy in the preloads regardless of the nutrient composition. Other groups (n = 12 per group), including normal-weight restrained men and normal-weight and obese restrained and unrestrained females, did not show such orderly energy compensation; joule-for-joule, the high-fat preloads suppressed intake at lunch less than did high-carbohydrate preloads. These results suggest that a relative insensitivity to the satiating effect of fat could be involved in the development and maintenance of obesity.

Adult↗
PubMed1994

Effects of delta 9-THC on marijuana smoking, dose choice, and verbal report of drug liking.

The effects of delta 9-tetrahydrocannabinol content of marijuana on cigarette smoking, dose choice, and verbal report of drug "liking" by adult males living in a residential laboratory were investigated. Marijuana cigarettes were available during programmed intervals while subjects were engaged in recreational activities. The tetrahydrocannabinol content of the cigarettes remained constant each day, but was changed across days. Subjects provided written ratings of drug liking at the end of each day. In the first study, placebo or active (2.3% delta 9-tetrahydrocannabinol) marijuana cigarettes were available for 1-, 2-, or 3-day intervals at varying times of day. The number of cigarettes smoked was unrelated to tetrahydrocannabinol content, although verbal reports of drug liking were consistently higher when marijuana cigarettes containing tetrahydrocannabinol were smoked. In a second study, a choice procedure, consisting of four 3-day blocks of 2 sample days and 1 choice day, was used. On sampling days, subjects smoked cigarettes varying in tetrahydrocannabinol content (0.0, 2.0, and 3.5%, w/w); on choice days they were allowed to choose between the two previously sampled doses. The number of cigarettes was not consistently related to tetrahydrocannabinol content. Ratings of drug liking were increased when marijuana cigarettes contained tetrahydrocannabinol, but ratings of marijuana containing 2.0% and 3.5% of the compound were similar. In contrast, subjects consistently chose the 3.5% dose over either the 0.0% or 2.0% dose. Dose choice was more sensitive to tetrahydrocannabinol content than either reports of drug liking or numbers of cigarettes smoked.

Adult↗
PubMed1994

Does package size matter? A unit-price analysis of "demand" for food in baboons.

In a study examining "demand" for food, responding of 8 adult male baboons (Papio c. anubis) was maintained under a fixed-ratio schedule of food reinforcement during daily 23-hr experimental sessions. Completion of the ratio requirement resulted in the delivery of one, five, or 10 1-g food pellets. Supplemental feeding was limited to fruit and a dog biscuit daily. Responding increased as "cost" was increased across a wide range of fixed-ratio values before reaching a maximum and then decreasing. Increasing the number of food pellets per delivery decreased total responding and the number of reinforcements per day. A unit-price analysis, in which intake was converted to grams per day and fixed-ratio values were converted to responses per gram, yielded demand functions that overlapped at lower unit prices. Under one or more multiple-pellet conditions, however, intake decreased more quickly than under the one-pellet condition as the fixed-ratio value was increased in all but 1 baboon. This indicates that even when using unit-price conversions, there was variability in total intake. Although unit-price conversions yielded intake data that were more consistent across conditions, conditions differed in response topography even at the same unit prices: Under the multiple-pellet conditions there were longer pauses in responding, running response rate was slower, and the first eating bout (i.e., "meal") of the session was smaller than under the one-pellet condition. These findings (a) support the heuristic value of a unit-price analysis for studying responding for and consumption of commodities that have similar attributes, and (b) indicate that different response topographies may result in similar intakes of a commodity.

Animals↗
PubMed1993

Ethanol as an energy source in humans: comparison with dextrose-containing beverages.

Six subjects participated in a residential study assessing the effects of consuming beverages containing energy derived from ethanol or dextrose on total energy and macronutrient intake. On certain days, subjects had to consume four beverages containing a total of approximately 2400 or 4600 kJ, equivalent to 22% and 42% of energy intake under conditions in which no-beverages were required. Each of four conditions (2400 kJ ethanol, dextrose; 4600 kJ ethanol, dextrose), and a no-beverage control condition was examined for 2 days. Subjects compensated for approximately 37% of the energy contained in the beverages such that total intake increased by 13% under the 2400 kJ conditions and 27% under the 4600 kJ conditions. There was no differential effect of ethanol content on energy intake. Cumulative intake curves indicated that caloric compensation was minimal following the consumption of beverages in the evening. While all of the beverage conditions significantly decreased energy intake derived from carbohydrate, the proportion of energy derived from fat, carbohydrate, and protein without the energy content of the beverages was essentially unaffected by dextrose- or ethanol-containing beverages. These results suggest that the effects of ethanol on intake of other foods can be accounted for by the energy content of ethanol as a beverage and by ethanol consumption in the evening when there is little time for daily caloric compensation, rather than by the pharmacological effects of ethanol.

Adult↗
PubMed1993

Behavioral effects of cocaine alone and in combination with ethanol or marijuana in humans.

Intranasal cocaine (COC) and oral ethanol (ETOH) were administered to one group of seven research volunteers during daily experimental sessions. Following the determination of baseline subjective and performance measures, an ETOH cocktail (0, 19.4, 38.7 or 58.1 g of ETOH in lemonade) was consumed over a 10-min period. COC hydrochloride (4, 48, 96 mg) was inhaled 35-min after the start of ETOH drinking. In a separate experiment, seven research volunteers received intravenous cocaine and smoked marijuana (MJ), alone and in combination during daily experimental sessions. Following the determination of baseline measures, a 1-g MJ cigarette (0-2.7% delta 9-THC, w/w) was smoked and 13 min after the start of MJ smoking COC hydrochloride (0, 16, 32 mg) was given intravenously. ETOH increased simple-reaction time and decreased DSST trials. COC decreased DSST trials, increased incorrect responses on a list-learning task and attenuated the effect of ETOH on DSST performance. Only combinations of the high COC dose and the high MJ dose increased errors on a repeated acquisition task. Intranasal COC increased ratings of 'Stimulated,' and 'High' and LSD scores on the ARCI which were unaffected by ETOH. Increased ratings of 'Sedated' following ETOH alone were attenuated by intranasal (i.n.) COC. Intravenous COC and smoked MJ alone both increased ratings of 'Stimulated' and 'High.' There was a trend for combinations of i.v. COC and MJ to prolong these elevations. The results suggest that the interactive effects of COC in combination with ETOH or MJ, after acute administration, are subtle and in need of further analyses to better understand polydrug abuse.

Administration, Intranasal↗
PubMed1993

Performance-based testing for drugs of abuse: dose and time profiles of marijuana, amphetamine, alcohol, and diazepam.

The time courses of the effects of acute doses of amphetamine (5 and 10 mg/70 kg), alcohol (0.3 and 0.6 g/kg), diazepam (5 and 10 mg/70 kg), and marijuana (2.0% and 3.5% delta 9-THC) on performance engendered by each of four computerized behavioral tasks were evaluated in six human subjects. These performance-based tasks have potential commercial utility for drug-use detection in the workplace. Alcohol and marijuana effects were reliably detected for up to three hours following dose administration with most procedures. Amphetamine and diazepam effects were also detected, but the dose effects and time courses were variable. The profile of behavioral effects varied across drugs, suggesting that performance-based testing procedures might be useful in discriminating which drug was administered and the time course of the drug's effects. Results indicate that repeated measurement with performance-based drug detection procedures can provide immediate indications of performance impairment in a cost-effective and noninvasive manner and, as such, would be a useful supplement to biological sample testing for drug-use detection.

Adult↗
PubMed1992

Behavioral response to diazepam in a residential laboratory.

Two groups of three healthy adult male volunteers without histories of sedative or other drug abuse participated in 15-day residential studies. Each day consisted of a private work period (10 AM to 4:30 PM), during which subjects participated in traditional laboratory performance tasks, and a social period (5 to 11:30 PM), during which subjects had access to recreational activities available under social or private conditions. Tobacco cigarettes and food were available throughout each day (9 AM to 12 PM). Diazepam (5 or 10 mg/70 kg) or placebo was administered orally twice daily in alternating three-consecutive-day intervals. Dosing order varied between groups. Diazepam had no effect on the total amount of time subjects spent in social conditions; however, the low dose increased verbal interaction, while the high dose decreased verbal interaction. Both doses disrupted performance on a second-order repeated-acquisition task but produced no effects on the other performance measures. Five of six subjects increased caloric intake following at least one dose, with the largest increases observed in subjects with the lowest baseline intake. Increases in subject reports of dose "Potency" and "Sedated" were also observed following the high dose. Diazepam doses routinely used in clinical settings influenced a variety of behaviors that are observed in the natural ecology, but not performance on accepted laboratory tasks.

Adult↗
PubMed1992

Self-administration of cocaine by humans: a laboratory perspective.

Laboratory research evaluating the behavioural and physiological effects of cocaine has produced important basic information relevant to the prediction and control of cocaine abuse. Adaptation for human subjects of laboratory procedures originally developed with non-humans has provided the methodology for assessing the relationship between cocaine-taking and the self-reported effects of cocaine. This laboratory model for evaluating drug-taking has been adapted to include all the routes of administration by which cocaine is abused. Data collected in cocaine choice/self-administration studies indicate that there is a generally good correlation between cocaine self-administration and its stimulant-like 'positive' effects. There are, however, areas in which these two measures clearly diverge, and drug self-administration procedures provide a sensitive measure of cocaine's effects when it is taken by the routes and in the patterns people use outside the laboratory. Combining these measures with other behavioural evaluations provides useful information for understanding cocaine use and abuse. In addition, and importantly, these laboratory procedures are useful tools in the development and assessment of treatment interventions which might be used effectively.

Choice Behavior↗
PubMed1992

Economic analysis of the effects of caloric alternatives and reinforcer magnitude on "demand" for food in baboons.

In a study examining "demand" for food, the responses of six adult male baboons (Papio c. anubis) were maintained under a fixed ratio schedule of food reinforcement during daily 22-h experimental sessions. Completion of the ratio requirement resulted in the delivery of a single 1-g food pellet. Caloric intake was studied under four food-access conditions: a single source of 1-g food pellets, two sources of pellets with different response costs, one source of pellets and one source of dextrose solutions with different response costs, or a single source of multiple pellets. Total daily caloric intake under minimal response-cost conditions did not vary across these four conditions. Increasing the response requirement for a single pellet decreased daily food intake. Compared to this single-pellet condition, increasing the response requirement: (a) decreased intake of multiple pellets to a much smaller extent; (b) decreased pellet intake to a larger extent when dextrose was available on an alternate lever and (c) decreased pellet intake to the greatest extent when pellets were available on an alternate lever. Changes in pellet intake were fitted to a theoretical equation derived by Hursh et al. (1988) to describe changes in demand for a commodity. Increasing the number of pellets per delivery decreased the rate of change in intake as cost increased, indicating decreased elasticity. Dextrose availability increased the rate of change in intake as cost increased, indicating increased elasticity. Availability of an identical food source increased the initial slope of intake without effecting the rate of change, thus also increasing elasticity. Mathematical analysis of demand curves provide a means of comparing the effects of diverse environmental manipulations on feeding behavior.

Animals↗
PubMed1992

Caloric, but not macronutrient, compensation by humans for required-eating occasions with meals and snack varying in fat and carbohydrate.

Six subjects participated in a residential study assessing the effects of covert macronutrient and energy manipulations during three required-eating occasions (breakfast, lunch, and afternoon snack) on total macronutrient and energy intakes. Overall, energy content of the occasions varied between approximately 3000 and approximately 7000 kJ (approximately 700 and approximately 1700 kcal) with the majority of the differential derived from either fat or carbohydrate (CHO). Each condition (high, medium, and low fat; high, medium, and low CHO; and no required eating) was examined for 2 d. Subjects compensated for the energy content of the required occasions such that only under the low-CHO condition (11,297 +/- 3314 kJ) was total daily energy intake lower than that observed in the absence of required occasions (13,297 +/- 1356 kJ). Only total energy intake under the high-fat condition (12,326 +/- 2548 kJ) was significantly different from its matched CHO condition (high-CHO condition: 14,665 +/- 2686 kJ). In contrast to the clear evidence for caloric compensation, there were no differential effects of condition on macronutrient intake, ie, there was no macronutrient compensation.

Adult↗