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Biomedical subjects

C R Schuster

Publications and source records attributed to C R Schuster.

At least 37 records · Page 2Linked to original sources
PubMed1996

Increasing opiate abstinence through voucher-based reinforcement therapy.

Heroin dependence remains a serious and costly public health problem, even in patients receiving methadone maintenance treatment. This study used a within-subject reversal design to assess the effectiveness of voucher-based abstinence reinforcement in reducing opiate use in patients receiving methadone maintenance treatment in an inner-city program. Throughout the study subjects received standard methadone maintenance treatment involving methadone, counseling, and urine monitoring (three times per week). Thirteen patients who continued to use opiates regularly during a 5-week baseline period were exposed to a 12-week program in which they received a voucher for each opiate-free urine sample provided: the vouchers had monetary values that increased as the number of consecutive opiate-free urines increased. Subjects continued receiving standard methadone maintenance for 8 weeks after discontinuation of the voucher program (return-to-baseline). Tukey's posthoc contrasts showed that the percentage of urine specimens that were positive for opiates decreased significantly when the voucher program was instituted. (P < or = 0.01) and then increased significantly when the voucher program was discontinued during the return-to-baseline condition (P < or = 0.01). Rates of opiate positive urines in the return-to-baseline condition remained significantly below the rates observed in the initial baseline period (P < or = 0.01). Overall, the study shows that voucher-based reinforcement contingencies can decrease opiate use in heroin dependent patients receiving methadone maintenance treatment.

Adult↗
PubMed1996

Evaluation of phentermine and fenfluramine, alone and in combination, in normal, healthy volunteers.

Recent clinical reports indicate that combined administration of phentermine and fenfluramine may have useful effects in the treatment of drug abuse. The present study was designed to evaluate the subjective and mood-altering effects of these drugs, alone and in combination, in normal healthy volunteers. Seven male and five female volunteers participated in an eight-session, double-blind study in which each subject received each of the following drug conditions: d-amphetamine (10 and 20 mg), phentermine (30 mg), fenfluramine (40 and 80 mg), phentermine (30 mg) with fenfluramine (40 mg), phentermine (30 mg) with fenfluramine (80 mg), and placebo. Sessions were conducted in a laboratory setting two or three days a week. Subjects completed standardized self-report questionnaires and psychomotor tests before and at regular intervals after each drug administration. Phentermine produced effects that were similar to those of d-amphetamine, whereas fenfluramine produced different and apparently aversive effects (e.g., it increased measures of anxiety and confusion). Phentermine reduced the apparently aversive effects of fenfluramine when the two drugs were given together. These results suggest that the combination of phentermine and fenfluramine would have a low potential for abuse.

Adult↗
PubMed1995

Conditioned reinforcing effects of capsules associated with high versus low monetary payoff.

The ability of a placebo drug capsule to serve as a conditioned reinforcer as a function of being paired with money reinforcement was evaluated. Volunteers were administered two differently colored capsules that presumably contained two different drugs. Although the volunteers were told they might contain a stimulant, sedative, or placebo, both capsules contained only a placebo. During sessions, volunteers participated in performance tasks. The tasks were programmed so that following one capsule, the amount of money obtained contingent upon responding was greater (high frequency of reinforcement) than following the other capsule (low frequency of reinforcement). During experiment 1, participants were exposed twice each to the two reinforcement conditions (sampling). During these choice sessions, 9 of 12 participants chose the capsule associated with the high frequency of reinforcement 2 or 3 times. Experiment 2 was designed to explore further whether the differential mood effects observed during sampling sessions could be conditioned. Although this could not be demonstrated, the self-administration results demonstrating the control of choice behavior even in the absence of pharmacological effects suggest that drugs may function as conditioned reinforcers. This finding has implications for broadening our understanding of the determinants of initiation and continued drug use.

Adult↗
PubMed1993

Probing the meaning of racial/ethnic group comparisons in crack cocaine smoking.

OBJECTIVE: To probe the meaning of reported racial and ethnic group differences in the prevalence of crack cocaine smoking and to estimate the degree to which crack cocaine smoking is associated with personal factors specific to race/ethnicity. DESIGN: Through reanalysis of data from the 1988 National Household Survey of Drug Abuse (NHSDA), we compared racial/ethnic group differences in crack cocaine smoking. To hold constant social and environmental risk factors that might potentially confound racial comparisons, we used an epidemiologic strategy that involves poststratification of respondents into neighborhood risk sets. A conditional logistic regression model was used to estimate the relative odds of crack use by race/ethnicity. PATIENTS OR OTHER PARTICIPANTS: The 1988 NHSDA interviewed 8814 individuals residing within households in the United States. Subjects were selected using a multistage area probability sampling of all residents aged 12 years and older. RESULTS: Once respondents were grouped into neighborhood clusters, the relative odds (RO) of crack use did not differ significantly for African Americans (RO, 0.85; 95% confidence interval [Cl], 0.37 to 1.93) or for Hispanic Americans (RO, 0.88; 95% Cl, 0.47 to 1.67) compared with white Americans. CONCLUSION: Findings of race-associated differences are often presented as if a person's race has intrinsic explanatory power. This analysis provides evidence that, given similar social and environmental conditions, crack use does not strongly depend on race-specific (eg, biologic) personal factors. Although the study finding does not refute the previous analysis, it provides evidence that prevalence estimates unadjusted for social environmental risk factors may lead to misunderstanding about the role of race or ethnicity in the epidemiology of crack use. Future research should seek to identify which characteristics of the neighborhood social environment are important and potentially modifiable determinants of drug use.

Adolescent↗
PubMed1993

Anorectic specificity as measured in a choice paradigm in rhesus monkeys.

The present report describes a new procedure for assessing anorectic specificity. Two rhesus monkeys (Macaca mulatta) surgically prepared with indwelling intragastric catheters were trained in a discrete trial choice paradigm to respond for either food or visual access to a room containing other monkeys. Our hypothesis was that a specific anorectic would reduce only food-maintained responding; responding to open a window would either not be affected or would increase. Caloric preloads, d-amphetamine, (d,l)-fenfluramine, and cholecystokinin octapeptide all decreased food-maintained responding and had no effect on or increased responding maintained by window opening. These results demonstrate that choice procedures are useful for assessing anorectic specificity.

Amphetamine↗
PubMed1992

Drug abuse research and HIV/AIDS: a national perspective from the US.

The National Institute on Drug Abuse (NIDA), the lead Federal agency charged with research on reducing the demand for illicit drugs in the US, has actively pursued the associated challenge of reducing drugs-related HIV transmission. Drug abuse-related spread of the virus occurs not only through sharing contaminated needles but also sexually to partners and perinatally from infected mothers to their offspring. Through a national research and demonstration program, NIDA supports primary AIDS risk reduction activities focused on identifying effective drug abuse prevention and treatment strategies. AIDS is increasingly a disease found in women, children, minorities, and people who live in rural areas. NIDA's efforts are clearly responsive to the changing nature of this epidemic. Among the many promising initiatives currently underway are a medications development program to find new pharmacotherapies for treating drug addiction; an array of National AIDS Outreach Demonstration Projects implementing alternative control strategies for drug abusers not attracted to or successful in drug abuse treatment; establishment of several treatment research units for designing and conducting studies on treatment effectiveness; and a variety of programs aimed at identifying and potentially reducing the risks of prenatal drug use to both mother and child. Effective dissemination of our findings is particularly critical to the overall impact of our research efforts. Collaborative activities teaming NIDA with a multitude of organizations also addressing AIDS related issues are designed to provide a synergistic impact on this complex and multifaceted public health crisis.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Recommendations for improving drug treatment.

Recognizing that drug use is both chronic and relapsing once an individual is addicted, and that treatment is effective in reducing drug use/misuse, improving drug misuse treatment is examined and research as well as practice recommendations are presented. Drug misuse treatment is now recognized in the United States to meet the expanding drug use problem and for reducing the spread of HIV. With that background, the current status of drug misuse treatment is reviewed, clinical issues are emphasized, and policy issues are noted. Recommendations include the need for uniform funding, linkage with community agencies, technology transfer, training, and expanding research and evaluation efforts.

HIV Infections↗
PubMed1990

Effects of cholecystokinin, d-amphetamine and fenfluramine in rats trained to discriminate 3 from 22 hr of food deprivation.

Attempts to assess similarities between the interoceptive stimuli of anorectic drugs and food satiation have generally been limited to human verbal reports. The purpose of the present study was to develop a procedure for assessing similarities between the interoceptive stimuli of food in the gut and various drugs known to alter food intake in rats. Rats (n = 23) were trained in a two-lever, food-reinforced, discrimination paradigm to press one lever when deprived of food for 3 hr and another lever when deprived of food for 22 hr. Criteria for stimulus control over responding were achieved after a mean of 92 (range = 26-175) training sessions. In time course tests, rats were tested when 22, 12, 6 and 3 hr food-deprived. As the number of hours of food deprivation decreased, the percentage of responses that occurred on the 3-hr food deprivation lever increased. In substitution tests, rats that were 22-hr food-deprived consistently responded as if they were 3-hr food deprived after administration of sweetened condensed milk preloads or cholecystokinin, but only occasionally after administration of water preloads, LiCl, d-amphetamine or fenfluramine. These results demonstrate that the presence of food in the gut can function as a discriminative stimulus to control lever choice in rats. Furthermore, they suggest that the discriminative stimulus effects of cholecystokinin, but not d-amphetamine or fenfluramine, are similar to those of food in the gut, and support the hypothesis that cholecystokinin plays a role in the regulation of food intake.

Animals↗
PubMed1989

Testing and abuse liability of drugs in humans.

In summary, there are a number of factors to be considered in abuse liability testing such as the purpose of the testing and its potential applications that determine which subject population we should employ. Furthermore, we should not expect to see a perfect correlation between abuse liability testing and the actual abuse of these drugs because there are many factors that will modulate or modify whether or not abuse liability becomes activated and the abuse of any specific drug becomes a social problem.

Amphetamines↗
PubMed1988

Relationship between the discriminative stimulus properties and subjective effects of drugs.

Behavioral pharmacologists have assumed that the properties of drugs that mediate their discriminative stimulus effects are related to aspects of drug actions that result in their subjective effects in humans. The basis of this assumption is examined in this chapter. Evidence to support this assumption includes the formal properties of the learning process involved in acquiring both behaviors. Although the procedures used to train animals to learn a drug discrimination are explicit, an analysis of how humans learn to attach verbal responses to unobservable internal subjective states appears to involve a similar learning paradigm. Additional evidence of the commonality of the two effects is that the results from drug discrimination studies in animals and studies evaluating subjective effects in humans yield similar drug classifications. However, when subjective drug effects are analyzed in more detail, it is clear that the concordance between the two approaches is not always good. On the other hand, when drug discrimination and subjective effects are both measured in humans, an examination of the results generated when individuals respond differently to the same drug indicates that the hypothesis that their discrimination is based upon a profile of subjective effects is supported.

Animals↗