Attentional absorption in marijuana and alcohol intoxication.

On a measure of psychological "absorption," alcohol users asked to refer to the alcohol-intoxicated state reported significantly lower mean absorption scores than did marihuana and alcohol users asked to refer to the marihuana-intoxicated state or to nonintoxicated occasions. Control conditions utilizing the Addiction Research Center Inventory scales showed that Ss (162 undergraduates) were capable of accurately accessing both the marihuana- and alcohol-intoxicated states. Responses indicative of cultural stereotypes of the drug states could not account for the results. Other results indicate that marihuana users scored significantly higher than either nondrug users or exclusive alcohol users on ratings of the affective pleasantness associated with those absorbing experiences reportedly characteristic of the marihuana state. The apparent reciprocal relationship between alcohol and marihuana intoxication with respect to psychological absorption, in conjunction with the affect results, may suggest differential reinforcing values associated with the alterations in consciousness produced by each drug. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A replicated study of self-reported changes in psychological absorption with marijuana intoxication.

In a cross-validated study with a total of 492 college students, marihuana users were asked to reference marihuana experiences exclusively and were administered the Sensation Seeking Scale and Differential Personality Questionnaire. Absorption scores (reflecting trait capacity for total attentional involvement) increased over a standard administration but could not be accounted for by a culturally stereotyped response pattern, demand characteristics of the testing situation, or effects of repeated administration of the scale. Results suggest that the overall increase for users was not merely a group effect but accurately reflected the type of change occurring for most users. Absorption scores decreased when Ss were asked to exclude all drug-related experiences. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social facilitation of marijuana intoxication: Impact of social set and pharmacological activity.

Conducted 2 experiments with a total of 120 males (mean age = 23 yr.) to determine to what extent marihuana intoxication is the result of drug effects, expectancy, social setting, or an interaction of these factors. In Exp. I, Ss 1st swallowed a placebo pill and then smoked either 2 placebo cigarettes or two marihuana cigarettes containing a total of l5 mg. D9-tetrahydrocannabinol (THC). The cigarettes were smoked in a setting designed to either facilitate intoxication ("up night") or interfere with it ("down night") through manipulation of S's expectancy and through modeling. Results indicate that the amount of marihuana smoked impaired cognitive functioning and was rated as more intoxicating than the placebo. Manipulations of setting and belief had no effect. In Exp. II, Ss smoked 2 cigarettes containing either placebo, 7.5 mg. THC, or l5 mg. THC. Ss who smoked placebo cigarettes 1st swallowed a pill containing either 10 or 25 mg. librium (chlordiazepoxide). Ss who smoked cigarettes containing THC received placebo pills. Smoking was done in either "up night" or "down night" contexts. Results suggest that social setting and belief interact with smaller doses of marihuana but not with large doses nor with placebo. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Volitional control of marijuana intoxication: A study of the ability to "come down" on command.

Studied the ability of experienced marihuana users to offset the behavioral consequences of marihuana smoking, using objective and subjective indices of intoxication. In a repeated test design, 10 Ss smoked placebo and 10 marihuana containing 1.2% tetrahydrocannabinol. The dependent variables were subjective rating of intoxication, pulse rate, and several performance measures. In a high-motivation condition, Ss were instructed to try and overcome the effects of the drug; in a low-motivation condition no special instructions were given. High-motivation Ss compensated for intoxication more than low-motivation Ss in a time-estimation task but not in short-term memory. Subjective intoxication and pulse rate were not differentially affected. Although compensation was task specific, the results demonstrate that in principle the ability to come down exists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medical marijuana

To evaluate the use of high-resolution magnetic resonance imaging (MRI) for the differentiation of skin tumors in the maxillofacial region, 60 patients (25 female) were examined in a 1.5-T whole-body MR imager with a 2.5-cm surface coil. Plain transverse T1-(TR 500 ms, TE 25 ms), T2-(2200 ms, TE 80 ms), fat-(TR 500 ms, TE 28 ms), and water-suppressed (TR 500 ms, TE 38 ms) SE sequences were used. Following the application of the paramagnetic contrast agent Gd-DTPA, transverse T-weighted and fat suppression sequences were repeated. Before and after contrast administration, tumor signal intensities and percent contrast enhancement were determined by a ROI technique. All tumors were classified by standard histologic technique and evaluated with regard to their response to contrast medium. Quantitative evaluation was performed by three independent radiologists. Additionally, signal- and contrast-to-noise ratios were calculated for each tumor type. All MRI findings were compared with histology. Significant contrast enhancement occurred in most tumors; malignant tumors displayed inhomogeneous enhancement. The optimal pulse sequences for tumor delineation are plain T1-weighted, water-suppressed, and contrast-enhanced fat-suppressed sequences. Tumors could not be specified by signal intensities or percent contrast enhancement, and CNR did not allow for malignant lesions to be differentiated from benign tumors. High-resolution MRI proved to be an adequate method for imaging skin tumors and their inner structure. Tumor typing was not possible by either contrast-administration or modification of sequence parameters. In this regard, further innovations in contrast agent design seem to be necessary.     

The effects of a monetary alternative on marijuana self-administration

We have used a variety of methods to characterize the genome of the archaeon Methanosarcina thermophila TM-1. Pulsed-field gel analysis indicates a genome size of 2.8 Mb. We have constructed a bacterial artificial chromosome (BAC) library of M. thermophila and have used it to generate physical maps for this organism. The library is made up of 384 clones with an average insert size of 58 kb representing 8.0 genome equivalents. The utility of the library for low-resolution physical mapping was shown by identifying NotI linking clones and using these to order the NotI macrorestriction fragments of M. thermophila into a 2.8 Mb map. Hybridization of nine single copy genes and a 16S rRNA sequence to these macrorestriction fragments forms the basis for the first genetic map in this organism. High-resolution physical maps, consisting of overlapping clones, have been created using HindIII fingerprints of BAC clones. In this way, we identified a minimal path of five clones that span a 270 kb NotI fragment. The ease of manipulating BAC clones makes the BAC system an excellent choice for the construction of low-resolution and high-resolution physical and genetic maps of archaeal genomes. It also provides a substrate for future genome-sequencing efforts.     

The effects of marijuana on human physical aggression.

30 male undergraduates received intense provocation following their ingestion of a low dose (.1 mg/kg), a medium dose (.25 mg/kg), or a high dose (.4 mg/kg) of delta-9-tetrahydrocannabinol. Each S was informed that he was competing in a reaction time (RT) task with another S in an adjoining room. At the beginning of each trial, he was told to select any 1 of 11 intensities of shock he wished his opponent to receive if his opponent lost the trial. If he lost, he would receive the shock his opponent had set for him. Regardless of who won, each S was able to see, following each trial, what level of shock his opponent had set for him. The frequency of wins and losses and the amount of shock received were programmed by the experimenter. Findings show that the Ss in the low-dose condition tended to respond in a more aggressive manner than the Ss in the moderate- and high-dose conditions. They set significantly higher shocks than Ss in the medium- and high-dose groups in a number of trials. Ss in the high-dose condition behaved in a relatively nonaggressive manner throughout the experimental session. Results support the consensus that marihuana does not instigate, precipitate, or enhance aggressive behavior. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of scales to measure attitudes toward marijuana and marijuana users.

450 undergraduates participated in the 2-phase development of a 22-item marihuana attitude scale. The final form of the scale, partitioned into 3 factorially defined, mutually exclusive subscales, deals with (a) the psychological, physiological, and sociological effects of marihuana on users; (b) marihuana as a psychosocial panacea; and (c) liberal-conservative ambivalence toward the usage of marihuana. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effectiveness of a marijuana expectancy manipulation: Piloting the balanced-placebo design for marijuana.

Although alcohol and nicotine administration studies have demonstrated that manipulating subjects’ expectancies regarding drug content affects drug response, research with marijuana has not adequately studied drug expectancy effects. The present pilot study was the first to evaluate the credibility and effect of expectancy manipulation on subjective measures and smoking patterns using a marijuana administration balanced-placebo design (BPD). In a 2 × 2 instructional set (told delta-9-tetrahydrocannabinol [THC] vs. told no THC) by drug (smoked marijuana with 2.8% THC vs. placebo) between-subjects design, the authors examined the effect of marijuana expectancy manipulation and the pharmacologic effect on affective and physiologic measures, cigarette ratings, and smoking behavior with 20 marijuana smokers (mean age = 20 years; 25% female). Large main effects of expectancy were found on ratings of cigarette potency, strength, taste, smell, and satisfaction, and observed smoking behavior. Pharmacologic effects were particularly evident for self-reported physical reactions to marijuana and cigarette potency and satisfaction ratings. This study demonstrated the feasibility of the BPD research with marijuana and yielded promising results for future studies examining the independent and combined effects of marijuana pharmacology and expectancies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The functional anatomy of sound intensity discrimination

The human neuroanatomical substrate of sound intensity discrimination was investigated by combining psychoacoustics and functional neuroimaging. Seven normal subjects were trained to detect deviant sounds presented with a slightly higher intensity than a standard harmonic sound, using a Go/No Go paradigm. Individual psychometric curves were carefully assessed using a three-step psychoacoustic procedure. Subjects were scanned while passively listening to the standard sound and while discriminating changes in sound intensity at four different performance levels (d' = 1.5, 2.5, 3.5, and 4.5). Analysis of regional cerebral blood flow data outlined activation, during the discrimination conditions, of a right hemispheric frontoparietal network already reported in other studies of selective or sustained attention to sensory input, and in which activity appeared inversely proportional to intensity discriminability. Conversely, a right posterior temporal region included in secondary auditory cortex was activated during discrimination of sound intensity independently of performance level. These findings suggest that discrimination of sound intensity involves two different cortical networks: a supramodal right frontoparietal network responsible for allocation of sensory attentional resources, and a region of secondary auditory cortex specifically involved in sensory computation of sound intensity differences.     

Pneumomediastinum in heroin and marijuana users

During the past three years, more than 500 patients were seen with mediastinal or cervical emphysema or both the Ben Taub General Hospital Emergency Center. In all but 15 there was a history of recent trauma or antecedent respiratory conditions with repeated sustained intrabronchial pressure, such as asthma. These 15 patients had a common history of repeated sustained Valsalva's maneuvers during marijuana smoking or during intravenous injections of heroin. The results of esophagography, bronchoscopy, and esophagoscopy were normal in these 15 patients. Conservative management consisted of close observation and re-evaluation for possible causes of secondary pneumomediastinum. All recovered without sequelae with resolution of the pneumomediastinum within 2 to 5 days. Radiographic and physical findings in primary pneumomediastinum resulting from prolonged intraalveolar hyperpressure are similar to those seen in patients with trauma or spontaneous rupture of the esophagus.     

Respiratory status of seventy-four habitual marijuana smokers

Previous studies of the long-term effects of habitual marijuana smoking on respiratory status and lung function have yielded conflicting results. In the present study, lung function tests obtained in 74 regular marijuana smokers (duration of smoking > two-five years; frequency of smoking three days/week to several times/day) who denied intravenous narcotic drug abuse were compared with similar tests performed in two groups of control subjects. One group consisted of individuals tested in a mobile laboratory who were computer-matched to the marijuana smokers for anthropometric characteristics and quantity and duration of tobacco smoking; the other group was comprised of 41 nonsmokers of marijuana who were tested in the same laboratory as the marijuana smokers. Paired and unpaired t analyses revealed lower values for specific airway conductance (-0.07 to -0.08 +/- 0.02; P < 0.001) in the marijuana smokers compared with either group of control subjects, but no differences in spirometric indices, closing volume or delta N2 750-1250. When non-tobacco smoking marijuana users (n = 50) were matched with either non-tobacco smoking or tobacco smoking control subjects, significant differences were again noted in specific airway conductance (P < 0.001) but not in spirometric tests, closing volume or delta N2 750-1250. These results suggest that habitual smoking of marijuana may cause mild, but significant, functional impairment predominantly involving large airways which is not detectable in individuals of the same age who regularly smoke tobacco. The clinical implications of these findings await further study.     

Adult marijuana users seeking treatment.

In an effort to study the efficacy of attracting and intervening with adult marijuana users, 290 men and 92 women were screened for participation in a treatment-outcome study focused on marijuana cessation. The well-educated, self-referred sample reported using marijuana on 79 of the past 90 days before testing. Indices of the severity of marijuana abuse and general psychopathology were in the clinical range for a majority of Ss. Ss who did not report evidence of alcohol or other drug abuse (n?=?144) reported less severe consequences of marijuana use and experienced less general psychological distress than Ss who also reported lifetime (n?=?165) or current abuse (n?=?73) of other substances in addition to marijuana. The findings indicate the need for clinical research targeting adults who are dependent on marijuana. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associations of marijuana use and sex-related marijuana expectancies with HIV/STD risk behavior in high-risk adolescents.

Multiple studies suggest an association of marijuana use with increased rates of sexual risk behavior and sexually transmitted diseases (STDs). Most studies have focused on global associations of marijuana use with sexual risk outcomes and few have examined relevant cognitive variables. Adolescents in the juvenile justice system are at elevated risk for HIV/STDs and preliminary evidence suggests that marijuana is a potentially important cofactor for sexual risk behavior in this population. This study evaluated global, situational and event-level associations of marijuana use and sex-related marijuana expectancies with sexual risk outcomes in a large, racially diverse sample of adjudicated youth (n = 656, 66% male, mean age = 16.7 years). Cross-sectional and prospective analyses identified associations of marijuana use and dependence symptoms with sexual risk outcomes, including lower frequency of condom use and higher STD incidence. Stronger sex-related marijuana expectancies predicted greater intentions for and frequency of marijuana use in sexual situations. In event-level analyses that controlled for alcohol, marijuana use predicted a significantly decreased likelihood of condom use; this association was moderated by sex-related marijuana expectancies. Mediation analyses suggested that behavioral intentions partly accounted for the prospective association of expectancies with marijuana use before sex. These results provide further evidence that marijuana use is a potentially important cofactor for HIV/STD transmission in high-risk adolescents and suggest that cognitive factors could be important for characterizing this association. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fatal flecainide intoxication

OBJECTIVE: The objective of this work was to examine the diversity within Australian isolates of Actinobacillus equuli and related organisms by the genotypic method of ribotyping. DESIGN: Ribotyping, performed using the enzyme HaeIII, was used to examine the diversity in 12 field isolates of A equuli (five being capable of fermenting L-arabinose), one field isolate of Pasteurella caballi and two unclassifiable field isolates. Isolates were obtained from Australian horses, except for three isolates of A equuli (one L-arabinose positive and two L-arabinose negative) which were obtained from horses and a pig in Africa. In addition, the type strains for A equuli and P caballi and a reference strain for Bisgaard Taxon 9 were included in the study. RESULTS: The ribotype patterns were analysed by computerised cluster analysis, yielding five clusters (A to E). All five of the L-arabinose positive A equuli were assigned to cluster A, with all the other seven A equuli isolates (all L-arabinose negative) and the type strain being assigned to cluster B. One of the two unclassified isolates formed cluster C along with the reference strain for Bisgaard Taxon 9. The remaining unclassified isolate formed cluster D. Cluster E consisted of the field isolate and reference strain of P caballi. CONCLUSION: The results of this study indicate that A equuli is a diverse species, with L-arabinose positive isolates of A equuli being quite distinct from typical L-arabinose negative isolates. Ribotyping appears to be a useful tool in confirming the identity of A equuli-like organisms from horses.