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Biomedical subjects

S J Robbins

Publications and source records attributed to S J Robbins.

At least 19 recordsLinked to original sources
PubMed2001

Results of a baseline urine test predict levels of cocaine use during treatment.

Sixty-one cocaine dependent outpatients submitted a single urine sample at least 1 week prior to entry into a 4-week treatment study. Participants were then expected to provide three urine samples per week during the month of treatment. The 61 patients studied here all completed treatment and provided an average of more than 11 of 12 scheduled urine samples. Participants who submitted a cocaine-positive sample prior to treatment provided more positive urine samples during the 4-week trial, were less likely to be completely abstinent during the month, and took longer to reach an initial abstinence criterion of three consecutive cocaine-free urines. Thus, a single pretreatment urine test represents a powerful predictor of subsequent cocaine use. The results suggest that future randomized trials stratify group assignment based on the results of a baseline urine test.

Adult↗
PubMed2001

A randomized, double-blind, placebo-controlled study of ritanserin pharmacotherapy for cocaine dependence.

Eighty cocaine-dependent individuals enrolled in outpatient treatment took part in a randomized, double-blind, placebo-controlled trial of ritanserin, a 5-HT(2) antagonist, as an adjunct therapy. Participants attended an outpatient day hospital therapy program each day and received tablets containing placebo or 10 mg ritanserin for a 4-week period. Primary outcome measures included retention in treatment, urine drug tests, and self-reports of craving. Secondary outcome measures were depression scores on the Beck and Hamilton inventories, negative mood as measured by the Profile of Mood States, and life functioning as measured by the Addiction Severity Index. Although participants showed improvement over the 4 weeks, there were no group differences on any of the measures. These results fail to support the use of ritanserin as a complement to outpatient psychosocial therapy for cocaine dependence.

Adult↗
PubMed2000

Mood state and recent cocaine use are not associated with levels of cocaine cue reactivity.

Eighty-one cocaine-dependent outpatients were assessed for their reactions to cocaine-related cues in a laboratory setting. All subjects contributed a urine sample prior to the session. Compared with non-drug control cues, the cocaine stimuli produced increases in physiological arousal, self-reports of high, craving, and withdrawal, and self-reports of negative mood. Subjects who tested cocaine-positive on the day of testing differed only in skin resistance responding from those who tested cocaine-negative. Changes in cue-induced physiological and self-report measures were also not associated with between-subject variations in mood as measured by the Profile of Mood States (POMS) questionnaire administered prior to cue assessment. Thus, variations in baseline mood and recent cocaine use history do not introduce an additional source of variability in cue reactivity measurements. However, negative mood states at the start of a session were associated with higher levels of self-reported craving, high, and withdrawal both before and after cue exposure.

Adult↗
PubMed1999

Comparing levels of cocaine cue reactivity in male and female outpatients.

Thirty-eight female and 26 male cocaine-dependent outpatients were exposed to cocaine cues in a laboratory setting. Stimuli consisted of an audiotape of patients discussing cocaine use, a videotape of simulated cocaine preparation and use, and the handling of cocaine paraphernalia. Overall, the stimuli produced significant decreases in skin temperature and skin resistance, and significant increases in heart rate, self-reported drug states (high, craving, and withdrawal), and self-reported negative moods. Females were more likely to report increased craving in response to the cues than males, but there were no other gender differences in any of the responses. Levels of reactivity in females were comparable to the results of previous studies with all male samples. These results support the use of a constant set of cues in future treatment studies employing gender-balanced patient samples.

Adult↗
PubMed1998

Cocaine use is associated with increased craving in outpatient cocaine abusers.

Sixty-one cocaine abuse patients provided self-reports of craving and urine samples 3 times a week. Within-subject analyses revealed several relationships between the measures. First, peak craving levels were higher for 2-3-day intervals during which cocaine use had occurred than for preceding or following abstinent intervals. Second, average craving ratings during cocaine use intervals were double the ratings given during abstinent intervals. Third, cocaine use was 4 times more likely to occur during a period of elevated craving than during comparison intervals. Finally, participants who provided at least 1 positive urine sample reported more craving increases over 4 weeks than did abstinent individuals. These results demonstrate a strong association between craving increases and naturally occurring cocaine use but do not allow a determination of whether craving caused cocaine use or cocaine use caused craving.

Adult↗
PubMed1998

Conditioning factors in drug abuse: can they explain compulsion?

There is a good deal of clinical evidence suggesting that compulsion to resume drug taking is an important part of the addiction syndrome. The symptoms comprising motivation to resume drug use, namely craving and compulsion, have been studied experimentally in human subjects. While much work remains to be done, there is evidence showing that these symptoms are influenced by learning. The research has been guided by animal studies demonstrating that drug effects can be conditioned. Much attention has been directed toward demonstrating the existence of drug conditioning in human addicts and exploring the neurological structures that may underlie such learned responses. We do not yet know the relative importance of learning in the overall phenomenon of relapse, and treatments based on conditioning principles are still under investigation.

Alcohols↗
PubMed1997

Comparing self-reported cocaine use with repeated urine tests in outpatient cocaine abusers.

Sixty-one participants in outpatient therapy for cocaine dependence provided urine samples and self-reports of cocaine use 3 times a week for 4 weeks. Participants later gave a retrospective self-report of cocaine use for the month on the addiction Severity Index (ASI). Comparisons with urine test values revealed substantial underreporting of cocaine use on both measures, and results from the 2 forms of self-report were only imperfectly correlated. More participants admitted to at least 1 cocaine use episode on the ASI than on the repeated self-reports, but the repeated reports provided a more accurate index of the relative frequency of cocaine use during the month. Self-reports can enhance cocaine use detection when urines are infrequently collected and can help determine whether consecutive positive urine samples represent elevated metabolite levels from a single drug use episode. However, self-reports cannot substitute for regular urine sampling.

Adult↗
PubMed1996

Failure of ritanserin to block cocaine cue reactivity in humans.

As part of a double-blind placebo-controlled study of the effects of ritanserin on cocaine use and craving, reactivity to cocaine-related events was assessed both before and during medication. Twenty-two patients receiving ritanserin and 23 receiving placebo were exposed to cocaine cues while continuous measures of heart rate, skin temperature, and skin resistance were taken. Self-reports of high, withdrawal, and craving were also collected. The cues produced significant physiological responding as well as significant increases in high and craving during both sessions. Ritanserin reduced cue-elicited decreases in skin temperature, but had no effect on heart rate and skin resistance or on cue-induced high and craving. The results demonstrate that cue reactivity is a robust phenomenon across two assessment sessions but fail to support the use of ritanserin as a means of reducing cue-elicited drug states.

Arousal↗
PubMed1994

Reliability and validity of 6-month timeline reports of cocaine and heroin use in a methadone population.

Fifty-nine persons addicted to heroin and maintained by methadone reported on daily heroin and cocaine use during 2 timeline calendar interviews administered 6 weeks apart. Retrospective reports covering 6 months were compared with urine samples taken weekly during the interval. Test-retest correlations were high and timeline estimates of drug use frequency were significantly correlated with the frequency of drug-positive urine results. Thus, timeline reports of drug-use frequency appeared both reliable and valid. Individual participants either over- or under-reported by an average of about 15%, and they did not identify instances of drug use with greater than chance accuracy when particular episodes of drug use occurred. These results support the use of timeline reports to make group comparisons of long-term drug use, but suggest that timeline data should not be used to identify specific drug-use episodes. Work with other drug-use population is necessary to extend these conclusions.

Adult↗
PubMed1993

Cue reactivity and cue reactivity interventions in drug dependence.

Despite a venerable history dating back to Pavlov and countless testimonials from patients such as those in the opening paragraphs of this chapter, there is much that remains to be learned about drug signals and, particularly, about ways of reducing their adverse effects on human drug users. There is a substantial amount of data showing increased craving and signs of physiological arousal to drug-related versus neutral cues in drug users for both drug classes reviewed here. Additional controlled studies will be useful in refining which responses among those studied are, in fact, conditioned in origin and therefore can be subjected reasonably to learning-based interventions. Most attempts to modify cue responsivity for clinical benefit have met with only modest success, and there is ample room for creative, but controlled, treatment-outcome studies. In recent years, several other groups have joined in the effort to understand drug-related cue reactivity, extending the research area to alcohol and nicotine (Monti et al. 1987; Niaura et al. 1988, 1989; Cooney et al. 1984; Hodgson and Rankin 1982; Drummond 1990; Laberg 1990). The interested reader is referred to several additional reviews of cue reactivity and cue exposure research related to alcohol and nicotine (Niaura 1988; Drummond 1990; Laberg 1990), opiates (Powell 1990), opiates and cocaine (Childress et al. 1988b; O'Brien et al. 1990), and all the preceding areas (Rohsenow et al. 1991).

Behavior Therapy↗
PubMed1992

Conditioned responses to cocaine-related stimuli in cocaine abuse patients.

Subjects with a history of free-basing and smoking cocaine but no history of opiate injections were exposed to three sets of stimuli. They received cocaine-related stimuli in one session, opiate-related stimuli in a second session, and non-drug stimuli on a third occasion. Compared to the opiate and non-drug cues, the cocaine-related events caused reliable decreases in skin temperature and skin resistance, and reliable increases in heart rate, self-reported cocaine craving, and self-reported cocaine withdrawal. Furthermore, control subjects lacking a history of cocaine or opiate use failed to show such differential responding. These results suggest that cocaine-related stimuli evoke Pavlovian conditioned responses in cocaine abuse patients. Such findings encourage continuing efforts to develop drug treatment strategies based on conditioning principles.

Adult↗
PubMed1992

Designing studies of drug conditioning in humans.

There has been much recent interest in the possibility that signals for drug use in humans acquire the ability to evoke classically conditioned (learned) states which motivate drug taking. Much data now suggest that cues paired with drug use come to elicit physiological responses and subjective reports of drug-related feelings like craving and withdrawal. However, the designs employed do not permit the conclusion that the observed responding results from classical conditioning. Studies which look directly at conditioning in the laboratory by pairing neutral stimuli with drug administration have not provided appropriate controls for unlearned effects such as sensitization or pseudo-conditioning. Similarly, studies which assess responding to cues thought to signal drug use in the natural environment (e.g., the sight of someone injecting heroin) have not adequately assessed whether such cues have unconditioned (unlearned) effects. Determining whether responding to drug-related cues results from classical conditioning has important implications for the development of drug treatments. Consequently, the purpose of the present review is to outline a set of criteria for determining that responses to drug-related stimuli in humans are learned. Existing studies are reviewed in light of these criteria and paradigms for further work are suggested.

Conditioning, Classical↗
PubMed1991

Western blot analysis of antibody specificities in subacute sclerosing panencephalitis: reactivity to measles virus proteins produced in persistently infected cells.

The specificity of serum antibodies from patients with subacute sclerosing panencephalitis (SSPE) and seropositive controls to measles virus proteins produced in acutely and persistently infected human cells was examined by western blot analysis. Sera from both SSPE patients and controls reacted to the H, N, and F1 virus proteins produced in acutely infected AV3 cells. However, while SSPE-derived sera reacted with the same proteins in persistently infected cells (AV3Al/MV), most control sera failed to react with the hemagglutinin protein produced in such cells (Hp). Most sera also reacted poorly with the M protein from either source, and the reactivity to the P protein was variable. Although the exact reason(s) for the different reactivities to the proteins were not determined, differences in antibody concentration did not appear to be responsible. The dramatic differences in the reactivity of SSPE and control sera to the Hp protein suggest that either the protein coevolves in persistent infections or multiple forms of the protein evolve in such infections and SSPE patients develop broad-spectrum humoral immunity as a consequence of exposure to them. Alternatively, over time there may be selective loss of some H-reactive antibody subsets by individuals who contract measles, but do not develop SSPE.

Adolescent↗
PubMed1991

Stimulation of measles virus replication by cyclic guanosine monophosphate.

Measles virus (MV) replication in acutely infected human cells was markedly stimulated following exposure to guanosine 3',5'-monophosphate (cyclic GMP). Addition of cyclic GMP to tissue culture fluids immediately following infection with the virus resulted in acceleration of virus-mediated cell fusion, increased synthesis of virus-specified proteins and a 50-fold increase in infectious particle production. No evidence of altered viral protein phosphorylation was found. The results suggest that cyclic GMP stimulates multiple stages of the MV replication cycle.

Cell Line↗
PubMed1990

Cue interaction in human contingency judgment.

Most studies of human contingency judgment have been based on the assumption that frequency information about one predictor is assessed in isolation of information about other predictors. Recent evidence, however, suggests that the judged predictive strength of one cue is influenced by the predictive strengths of other copresent cues. Two experiments demonstrate that stimuli with the same outcome contingencies may nonetheless have different predictive strengths as the result of cue interaction. The first experiment, in which a within-subject design was used, provides a demonstration of blocking. A stimulus presented in compound with a strong predictor was rated as less predictive than another stimulus that was presented in compound with a nonpredictive cue. In the second experiment, cue interactions in conditioned inhibition were examined. A stimulus gained negative predictive strength as the result of compound presentations with a positive predictor when the outcome was not presented. This negative predictor was compared with an otherwise analogous stimulus that was not presented in compound with a positive predictor. These results support the use of animal-conditioning models as accounts of human contingency learning.

Adult↗
PubMed1989

Cloning and molecular characterization of the myxoma virus genome.

Restriction enzyme cleavage maps of the genomes of the Uriarra (Ur), Glenfield (GV), and Lausanne (Lu) strains of myxoma virus were deduced for the enzymes EcoRI, KpnI, BamHI, SalI, HindIII, BglI, PstI, and PvuII. Restriction maps for the three strains were indistinguishable with the exception of an additional KpnI site in the Lu genome at map position 38.8. Genomic DNA fragments were cloned into the plasmid vector pGEM-3 and the viral genome was determined to be 163.6 (+/- 0.2) kb in length. Covalently closed terminal fragments were identified by electrophoresis of "snapback" fragments and the 5.3 kb BglI end fragment was cloned after S1 nuclease digestion of the hairpin structure.

Blotting, Southern↗