Interaction between Marihuana and Ethanol: Effects on Psychomotor Performance

This is a report of the results of a placebo-controlled study in which the effects of the interaction between ethanol and marihuana on drug plasma concentrations, subjective ratings of intoxication, heart rate acceleration, and psychomotor performance were investigated. Six healthy, male, paid volunteers, moderate users of ethanol and marihuana, participated in the study. Ethanol (0.42 g/kg, 0.85 g/kg, or placebo) was administered over a 30-min interval. Fifteen minutes later the subjects smoked, in their customary manner, NIDA cigarettes containing 2.4% or 0.0004% (placebo) delta-9-tetrahydrocannabinol (THC). Each subject was tested in a single-blind, latin-square crossover design with the following six conditions: placebo ethanol/placebo marihuana; low dose ethanol/placebo marihuana; high dose ethanol/placebo marihuana; placebo ethanol/marihuana; low dose ethanol/marihuana; and high dose ethanol/marihuana. The variables measured in the study were: (a) subjective rating of ethanol and/or marihuana intoxication; (b) heart rate; (c) accuracy and latency of response in the Simulator Evaluation of Drug Impairment (SEDI) task; (d) blood ethanol concentration by gas chromatography; and (e) plasma concentration of THC by radioimmunoassay. The results indicate that the decrements due to ethanol in performance of skills necessary to drive an automobile were significantly enhanced by marihuana in an additive and perhaps synergistic manner. The administration of ethanol prior to marihuana smoking did not produce significant effects on the subjective rating of "high," heart rate acceleration, or THC plasma concentration.     

Utilization of outpatient mental health services after inpatient alcoholism treatment

It is generally agreed that use of aftercare services following discharge from alcoholism treatment is optimum for patients to achieve long-term recovery. However, the quantity and duration of utilization of such services in non-experimental settings are generally unknown. Using secondary data sources, we studied 5,635 alcoholics completing formal extended inpatient treatment and 1,860 alcoholics discharged from brief inpatient hospitalizations in Department of Veterans Affairs medical centers. Weekly use of outpatient mental health services (OPMH) prior to hospital admission was equally low for both patient groups (approximately 2-3% of patients) until four weeks prior to admission, at which time OPMH use increased, particularly for the extended treatment group. In the four weeks after discharge, use of OPMH services was substantially higher for patients with extended treatment compared to those with brief hospitalizations (40% vs. 18%), with 22% of patients completing treatment utilizing such services in the first week after discharge. Utilization steadily decreased until only 8% and 4% of both groups, respectively, were using OPMH services at the end of six months after discharge. Study results suggest the need to examine barriers to outpatient mental health utilization after discharge as well as interventions to increase compliance with long-term aftercare.     

Susan Britton Wills Unit,Bristol General Hospital,Multidisciplinary, General Hospital and Community Psychiatry

The Susan Britton Wills Unit at the Bristol General Hospital is a small and busy multidisciplinary psychiatric unit, providing a wide range of in-patient, out-patient and day-patient services for the residents of Bristol Health District.

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Effectiveness of a brief workshop designed to improve teaching performance at the University of Alberta.

PURPOSE: To determine whether a two-day teaching enhancement workshop at the University of Alberta improved participants' teaching performance as rated by students. METHOD: Workshop participants (academic staff or residents) were asked to assess the value of the workshop. In addition, students were asked to rate instructors' teaching abilities before and after the instructors participated in the workshops, by completing a five-statement questionnaire routinely used to assess instruction at the University of Alberta. For control purposes, ratings were also obtained for a group of instructors who had not taken the workshop, over a similar time period. The authors used data from 1993-2002. RESULTS: The participants uniformly regarded the workshops as helpful. Both faculty and residents regarded the short teaching exercise as the most important component of the program. Of the instructional sections, the presentations on objectives and on structure (set, body, closure) were rated most highly by both groups. The students' mean ratings for the instructors after the workshop were significantly increased, while ratings for those who had not taken the workshop were unchanged CONCLUSION: Short teaching-enhancement workshops are regarded by the participants as helpful in improving their instructional skills. This view is supported by a significant increase in students' ratings of the instructors after they had taken the workshop.     

Stereospecific monoclonal antibodies to nicotine and cotinine and their use in enzyme-linked immunosorbent assays

Stereospecific monoclonal antibodies (McAb) have been prepared against the tobacco alkaloid (S)-(-)-nicotine and its major metabolite (S)-(-)-cotinine. Nine anti-nicotine and 4 anti-cotinine hybridomas, selected by a screening procedure that utilized immunoprecipitation of the ³H-labeled natural isomers of nicotine or cotinine, were grown in the ascites fluid of pristane-primed syngeneic BALB/c mice. Antibodies in concentrations up to 7.5 mg/ml ascites and with binding affinities that generally exceeded 10⁸ M⁻¹ were obtained. Enzyme-linked immunosorbent assays (ELISAs) were developed in which nicotine or cotinine derivatives bound covalently to poly- -lysine werecoated onto wells of polyvinyl chloride microtiter plates. Coated wells were incubated sequentially with McAb in the presence or absence of inhibitor, rabbit anti-mouse immunoglobulin, then horseradish peroxidase-labeled protein A (HRP-SpA) before addition of substrate. The antibodies are highly specific and show minimal cross-reactivity with several nicotine metabolites and other structurally related compounds. In the respective assays, only 0.25 ng (S)-(-)-nicotine and 0.12 ng (S)-(-)-cotinine are required to give 50% inhibition of antibody binding, and as little as 0.05 ng nicotine and 0.02 ng cotinine give 15% inhibition. These assays are 5–10 times more sensitive than analogous ELISAs developed with rabbit antisera and HRP-SpA or conventional radioimmunoassays (RIAs) that utilize the rabbit antisera and ³H-labeled ligands. There was good correlation between the levels of nicotine (r = 0.967) found in saliva samples from smokers and non-smokers assayed by McAb-based ELISAs and conventional RIAs.     

False negative hepatitis B surface antigen detection in dialysis patients due to excess surface antigen: postzone phenomenon.

Renal dialysis patients are well known to have a high incidence of hepatitis B carrier state. In studying a group of 63 long-term dialysis patients, 10 were found to be positive for hepatitis B surface antigen by radioimmunoassay (RIA). Surprisingly, however, only three of these RIA positive patients were positive by counter immunoelectrophoresis (CIEP). The discrepancy could not be accounted for by the difference in sensitivity of the two methods. The cause for the negative reactions by CIEP in seven patients was found to be the marked excess surface antigen in these sera which produced false negative results by the postzone phenomenon. After dilution all seven sera were positive by CIEP, requiring a dilution up to 1/20 to produce a positive result. Also, all seven sera were positive by the less sensitive Ouchterlony double diffusion.     

The effect of surface macrotexture and hydroxylapatite coating on the mechanical strengths and histologic profiles of titanium implant materials

A mechanical and histological evaluation of uncoated and hydroxylapatite-coated titanium implant materials was performed. Cylindrical implants of uncoated commercially pure (CP) titanium and hydroxylapatite-coated Ti-6Al-4V alloy were studied using a transcortical model, with implants evaluated after periods of 3, 5, 10, and 32 weeks. All implants had a surface macrotexture consisting of a series of semicircular annular grooves, approximately 750 micron in maximum depth. The attachment characteristics of interface shear stiffness and interface shear strength were determined by mechanical push-out testing. Nondecalcified histologic and microradiographic techniques, with implants in situ, were used to evaluate the response to the implant materials and the presence of the surface macrotexture. Mechanical testing results indicated that the hydroxylapatite-coated implants exhibited significantly greater values of maximum interface shear strength than the uncoated implants after all time periods. Interface shear stiffness was also significantly greater at all time periods for the hydroxylapatite-coated implants as compared to the uncoated implants. Histological evaluation after 3 weeks revealed an osteoid layer covering on all areas coated with the hydroxylapatite material; mineralization of this layer appeared to be complete after 10 weeks. In all cases, longer-term implants demonstrated mineralization of interface bone directly onto the hydroxylapatite coating, and in no case was a fibrous layer observed between the hydroxylapatite coating and the interface bone. Sections from the uncoated CP titanium implants revealed a thin fibrous layer present in nearly all areas. Only isolated regions of direct bone-implant apposition were observed for the uncoated implants. The presence of this fibrous tissue layer, however, apparently did not adversely affect the development of considerable attachment strength. The results from this study indicate that the hydroxylapatite coating can significantly increase the attachment strength of implants which rely upon bone apposition for fixation. In addition, the hydroxylapatite coating provides an osteophilic surface for bone deposition, and allows for a more rapid development of implant-bone attachment.