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Biomedical subjects

C R Schuster

Publications and source records attributed to C R Schuster.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Kinetics of cocaine in humans after intravenous and intranasal administration.

Cocaine kinetics were studied in four subjects after intravenous and intranasal administration. For intravenous administration cocaine hydrochloride (32 mg) dissolved in physiological saline was injected in 1 ml volume over a 1 min period. Intranasal cocaine was administered as 100 mg powder consisting of an appropriate dose of cocaine hydrochloride (64 and 96 mg) mixed with lactose powder. Subjects were instructed to inhale the mixture through a 5 cm straw within 1 min. Cocaine kinetics, after intravenous injection, conform to a one-compartment open model with first-order elimination. After intranasal administration, cocaine kinetics conform to a one-compartment model with first-order absorption and first-order elimination. The mean half-life of cocaine for intravenous injection in four subjects was 41.4 +/- 8.2 min (mean +/- S.E.M.) and the range was 19 to 64 min. There were statistically significant differences in the mean area under the concentration-time curve (AUC) following intravenous and intranasal administration. The AUC was dose-dependent and the fraction of the dose absorbed after 64 mg intranasal cocaine was significantly lower than after 96 mg dose (p less than 0.05).

Administration, Intranasal↗
PubMedDate not supplied

Single-dose study of nabilone in anxious volunteers.

The effects of single oral doses of nabilone, a synthetic cannabinoid, were studied in eight anxious volunteer subjects. Each subject had two exposures to placebo and three dose levels of nabilone at one-week intervals in a single-blind balanced Latin-square design after the nabilone dose range was determined by each subject's response to a test dose. Heart rate and blood pressure were monitored. The Profile of Mood States (POMS), a self-rating adjective checklist, was used as the quantitative measure of subjective effects. Four subjects performed a continuous avoidance procedure. High doses (4 or 5 mg) of nabilone produced orthostatic hypotension in these subjects. Mild dose-related increases in heart rate also occurred. Despite the occurrence of highly significant levels of sedation, there were no significant effects of nabilone on the continuous avoidance procedure. Two of these four subjects experienced an antianxiety effect from low (1 or 2 mg) nabilone doses. Four other subjects received comparatively lower doses of nabilone and performed on three behavioral tasks at intervals before and after drug: a recognition memory procedure, a task requiring spaced responding at a controlled rate, and a reaction time task. In these subjects there were no reliable effects on blood pressure or heart rate, no significant subjective effects on the POMS, and no antianxiety effects. Drug effects were also minimal on the three behavioral tasks.

Adult↗
PubMedDate not supplied

Interactions between atropine, chlorpromazine and cocaine on food reinforced behavior.

Previous investigations have demonstrated the ability of atropine and chlorpromazine pretreatment to increase intravenous cocaine self-administration in rhesus monkeys. These results were interpreted as resulting from either an antagonism of cocaine's reinforcing effect or an effect of cocaine which may interfere with its self-administration. The generality of the postulated drug antagonism was tested in monkeys exhibiting stable FR10 food-reinforced behavior. Intramuscular pretreatment with 0.25-4.0 mg/kg of chlorpromazine significantly depressed this behavior as did pretreatment with 0.25-2.0 mg/kg of atropine. These same dosages had been shown to increase cocaine self-administration. Fifteen-minute influsions of cocaine (1.0-10 mg/kg), which began 15 min after session onset, also resulted in a depression of food reinforced behavior. When chlorpromazine pretreatment and cocaine infusion were combined, the decrement in food reinforced responding was lessened. However, when cocaine infusion and atropine pretreatment occurred concurrently, the depression in responding was increased. These data indicate that chlorpromazine may nonspecifically antagonize the behavioral effects of cocaine; whereas, atropine may enhance these effects.

Animals↗
PubMedDate not supplied

A mild restraint and chronic venous catherization system for cats.

An inexpensive and minimally restrictive restraint system for cats is described which protects any temporary connections to chronic physiological implants during recording sessions and permits free movement of the head and extremities for behavioral studies. Procedures for constructing and implanting a chronic indwelling venous catheter device are also described which allows, directly with a syringe of via a connector system, for intravenous drug infusions in cats. These catheters have remained intact and relatively free of infection for a period of months before tissue rejection begins at the site of the subcutaneous implant.

Animals↗
PubMedDate not supplied

The relationship between self-reported cocaine withdrawal symptoms and history of depression.

This study examined the relationship between cocaine withdrawal and lifetime history of depression (major depression, dysthymia). Participants with a history of regular cocaine use (n = 146) were administered the Structured Clinical Interview for the DSM-IV (SCID) and were asked to recall whether they experienced any of the six DSM-IV cocaine withdrawal symptoms. Results of bivariate analyses demonstrated that those meeting criteria for the cocaine withdrawal syndrome (dysphoria plus two or more other symptoms), in comparison to those who did not, were significantly (P<.001) more likely to have a lifetime history of depression. Lifetime history of depression was also more common in those individuals reporting the withdrawal symptoms of "dysphoria" (P<.001), "insomnia/hypersomnia" (P<.05), "vivid unpleasant dreams" (P<.01), and "psychomotor agitation/retardation" (P<.01). These relationships remained significant after controlling for demographics, severity of addiction, and the presence of opiate, alcohol and cannabis dependence or abuse. The withdrawal symptoms of "fatigue" and "increased appetite" were not associated with mood history. Results suggest that lifetime history of depression is strongly related to whether or not a cocaine abuser self-reports withdrawal symptoms. Several competing hypotheses regarding the nature of this relationship are discussed.

Adult↗
PubMedDate not supplied

[AIDS and intravenous drug abuse].

The importance of intravenous drug-abuse as a vehicle of HIV and AIDS is evidenced on the basis of recent epidemiological data gathered in the USA. The rate of seropositivity among intravenous drug-addicts (whose total number i is close to one million) is estimated at more than 20 percent. Besides direct contamination, risks of contamination of sexual partners and their offspring can be evaluated from these figures. The programme developed by the National Institute on Drug Abuse against AIDS, aimed at that particular target population, is presented in its various aspects, including basic research, treatment and prevention.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Intravenous drug use and AIDS prevention.

Research programs of the National Institute on Drug Abuse take a broad approach to investigating the problems of intervention in intravenous drug use and its relation to the AIDS epidemic. Current prevention strategies are directed to reducing the rates of infection and the progression among the infected to clinical symptoms. Programs test alternative prevention models and focus on the epidemiology of the problem and on basic studies of specific high-risk behaviors. Ultimately, the problem requires community involvement to encourage behaviors which will reduce exposure on the part of drug users, their sexual partners, and their children.

Acquired Immunodeficiency Syndrome↗