Hospital-acquired infections documented by repeated annual prevalence surveys over 15 years.

OBJECTIVE: To estimate the benefits of iterative prevalence surveys in detecting trends of hospital-acquired infections (HAIs). METHODS: On the basis of the French protocol for national prevalence studies, HAI data of 15 consecutive annual surveys performed at the same period by the same group of investigators was gathered in a single database to describe the trend of HAIs in a University Hospital over a 15-year period. RESULTS: A total of 20,401 patients were included. Overall, the prevalence of patients presenting with at least one HAI acquired in our University Hospital was 5.1% [95% CI, 4.8-5.4%]. The prevalence of HAIs and antimicrobial drug use significantly decreased over time (P<0.01). CONCLUSION: Despite limitations, repeated prevalence surveys can be a useful tool for promoting control measures to better prevent HAIs.

Use of the Zung depression scale in patients with traumatic brain injury: 1 year post-injury.

OBJECTIVE: The purpose of this study was to examine if the physical disabilities of patients with traumatic brain injury (TBI) would influence the assessment of depression when using the Zung depression scale. METHOD: Patients with TBI (n=59) were assessed 1 year after injury for depression by both a psychiatrist and the use of the Zung depression scale. RESULTS: By psychiatric evaluation, seven of 17 (41%) patients with severe TBI and one of 20 (5%) of the patients with moderate TBI were diagnosed with major depressive disorder. With the Zung depression scale, 10 of 17 (59%) patients with severe TBI met the cut-off (scored >55) for depression, whereas none of the patients with moderate (n=20) or mild (n=22) TBI did. The mean (SD) scores of the somatic scale were 2.91 (0.93), 2.49 (0.92) and 1.25 (0.43) for each group. The mean scores of the affective scale were 2.58 (0.90), 1.85 (0.79) and 1.24 (0.46). For patients with moderate (p<0.05) and severe (p<0.10) TBI, scores on the somatic items exceeded scores on their affective items. No difference in somatic and affective scale scores was noted for the patients with mild TBI. CONCLUSION: The increased endorsement of somatic results may be the somatic difficulties associated with traumatic brain injury.

Human methadone self-administration: effects of diazepam pretreatment.

The effect of diazepam on methadone self-administration was examined. Five methadone-maintained patients with a history of benzodiazepine abuse were recruited. Patients were stabilized on 80 mg of methadone per day. After stabilization patients participated in methadone self-administration sessions. During each session, 128 presses (fixed ratio 128) of 1 button delivered 10 ml of 0.054 mg/ml methadone solution. The same number of button presses on a 2nd button delivered 10 ml of vehicle. Forty-five min prior to the self-administration session, 0 (placebo), 5, 10, or 20 mg per 70 kg body weight diazepam was administered. Ratings of drug liking, goodness, strength, and high were collected 5, 30, 60, 90, and 150 min after the end of the self-administration session. Diazepam pretreatment significantly decreased the amount of methadone consumed. The 10- and 20-mg diazepam doses significantly increased reports of good, like, strong, and high.

Smoking cessation in women with cardiac risk: a comparative study of two theoretically based therapies.

This gender-specific research study compares the relative effectiveness of two theory-based interventions targeting women who smoke. Women with coronary artery disease (CAD; n = 53) or CAD risk factors (n = 107) were randomly assigned to either coping-skills Relapse Prevention (RP) treatment or an educational/supportive treatment based on Health Belief Model (HBM) principles. RP was comparable, but not superior to HBM treatment, as indicated by the lack of differential smoking outcomes at 3 and 6 months. RP was more effective than HBM for women with low self-efficacy, as predicted. The presence of a smoking-related disease had a substantial effect on smoking status, in that the odds of being abstinent at 6 months were 2.2 times greater for non-diagnosed women when compared with CAD women. These findings indicate that more potent relapse prevention interventions are needed to increase cessation rates in women who smoke, especially those with established heart disease.

Context modulates effects of nicotine abstinence on human cooperative responding.

The effects of ad libitum smoking, abstinence, and 0-, 2-, and 4-mg nicotine gum on human cooperative responding were examined. Participants were provided the opportunity to respond cooperatively or independently to episodes initiated by a computer-simulated other person. Participants could also initiate episodes that ostensibly provided the other person the opportunity to respond cooperatively or independently of the participant. Working cooperatively added points to both the participant's and other person's counters. Working independently added points only to the participant's counter. Results demonstrated that abstinence decreased cooperative responses during episodes initiated by the computer-stimulated other person. Relative to abstinence and placebo gum conditions, ad libitum smoking and administration of 2- and 4-mg nicotine gum increased these cooperative responses. No gender differences were observed. The number of cooperative episodes initiated by the participants was not affected significantly by the smoking or gum conditions. Nicotine increased reports of vigor and decreased abstinence-engendered reports of depression, anger, confusion, and tension. The difference in the effects of nicotine abstinence on the 2 classes of cooperative responding demonstrates that the social contingency mediates the behavioral effects of abstinence.

Matching under nonindependent variable-ratio schedules of drug reinforcement.

Response-contingent deliveries of oral pentobarbital maintained responding of 3 rhesus monkeys during daily 3-hr sessions. Deliveries of pentobarbital were arranged under nonindependent concurrent variable-ratio variable-ratio schedules. Responses to either schedule counted toward completion of both variable-ratio schedule requirements. This schedule is similar in some respects to conventional concurrent variable-interval variable-interval schedules, in which passage of time counts toward completion of the interval value on both schedules. Restricted nonindependent concurrent variable-ratio variable-ratio schedules were also studied. On that schedule, when a drug delivery was assigned to one spout, it had to be collected before responses on the opposite spout again counted toward completion of the schedule requirements. Relative reinforcer magnitude was varied by changing the drug concentration on one schedule while keeping the drug concentration constant on the other variable-ratio schedule. Under both types of concurrent variable-ratio schedules, the relative rate of responding corresponded to the relative drug intake. Unlike earlier studies of concurrent variable-interval variable-interval intravenous cocaine reinforcement, preference was proportionate to concentration, and exclusive preferences did not develop. The relationship between relative rate of responding and relative drug intake was well described by the generalized matching law.

Effects of nicotine on methadone self-administration in humans.

The effects of nicotine abstinence, ad libitum smoking, and 0, 2, and 4 mg nicotine gum on methadone self-administration were investigated. Five methadone-maintained patients with a history of smoking (18-30 cigarettes/day) were recruited as subjects. Upon arrival expired carbon monoxide levels were measured to confirm self-reported abstinence of 10-12 h. At 30 min prior to the methadone self-administration session, two response options were concurrently available. When a 64-button press requirement (FR64) was completed, 10 ml of 0.054 mg/ml methadone solution, or vehicle, was delivered. Immediately following, and 30, 60, 90, and 120 min after the self-administration session, expired carbon monoxide levels and typical symptoms of nicotine withdrawal were assessed. Relative to abstinence, subjects consumed more methadone following the 4-mg nicotine gum and ad libitum smoking conditions. Ratings of cigarette craving were significantly less following ad libitum smoking or administration of 4-mg nicotine gum, than following abstinence. Implications for understanding opioid and nicotine interactions are discussed.

Effects of acute and chronic doses of naltrexone on ethanol self-administration in rhesus monkeys.

The effects of acute and chronic administration of intramuscular naltrexone (0.1, 0.3, 1.0, and 3.0 mg/kg) on oral ethanol (8%) self-administration were examined. Naltrexone (1.0 mg/kg) effects on the self-administration of ethanol concentrations ranging from 0.5 to 8% (w/v) were also investigated. Rhesus monkeys with substantial histories of drug and ethanol drinking served as subjects. During daily 3-hr sessions, monkeys were presented with ethanol solutions, concurrently available with water, under fixed-ratio reinforcement schedules. Naltrexone decreased the consumption of ethanol (g/kg). Biphasic temporal effects were observed within sessions. Naltrexone dose-dependently decreased the number of ethanol deliveries by a maximum of 56% (n = 18; 3 monkeys x 6 sessions) during the first hour of the session. During the second and third hours, however, ethanol intake recovered such that maximum decreases over the 3-hr session were approximately 27% (n = 18), and the mean decrease was 16% (n = 18). Often marked tolerance was observed, such that the effects of acute naltrexone administration were greater than effects after chronic administration. The self-administration of low ethanol concentrations (< or =2% w/v) was increased in several monkeys, by up to 340%, after naltrexone pretreatment. In summary, the effects of naltrexone on ethanol self-administration, in drug- and alcohol-experienced rhesus monkeys, are not characterized by unitary decreases in measures of ethanol self-administration. Rather, differential naltrexone effects were a function of experimental parameters, including the dose and number of naltrexone injections, the ethanol concentration, and the time point of measurement.

Human ethanol self-administration. I: The interaction between response requirement and ethanol dose.

The effects of work requirement on human ethanol self-administration were systematically examined. Healthy volunteers with a history of moderate alcohol consumption (12 to 16 drinks per week) were recruited as subjects. Four subjects self-administered 4, 8 or 16% w/v ethanol solution contingent upon completion of a fixed-ratio (FR) response requirement. The ratio requirements were FR 32, FR 64 and FR 128 responses. Ethanol consumption at lower doses decreased with increases in FR. Ethanol consumption at the high dose was greatest across all ratio requirements and was unchanged by increases in the ratio requirement, indicating greater relative reinforcing effects of the high dose of ethanol. Ethanol consumption was sensitive to unit price with 53-82% of the variance explained by the unit price analysis.

Human methadone self-administration: effects of dose and ratio requirement.

The effects of response requirement and small doses of methadone on human oral self-administration of methadone were examined. Three methadone maintenance patients stabilized at a dose of 80mg methadone per day were recruited as subjects. Completing a response requirement, fixed ratio (FR) of 32, 64 or 128 responses (FR32, FR64, FR128) on one button dispensed 10ml of drug solution. Completing the equivalent response requirement on a second concurrently available response button dispensed 10ml of vehicle. The opportunity to respond was unavailable until the drug or vehicle had been consumed. Each 10ml of drug solution contained methadone doses of 0.027, 0.054 or 0.108mg/ml. The frequency of deliveries was limited so that subjects could not ingest more than 54mg of methadone; the difference between the 80mg daily methadone dose and the methadone consumed in session was administered 30min post-session. At FR64 and FR128 the frequency of deliveries decreased, at the 0.054 and 0.027mg/ml doses, relative to the frequency of deliveries at FR32. The amount of methadone consumed increased with increases in methadone dose and decreased with increases in FR size. These results demonstrate the reinforcing effects of small unit doses of methadone. This procedure provides a sensitive baseline for examining effects of other pharmacological interventions on methadone ingestion in humans.

Behavioral treatment of cocaine-dependent pregnant women and TB-exposed patients.

Health-compromised drug-dependent patients require specialized treatment that addresses both drug use and health risks. This preliminary study examines the efficacy of a contingency management procedure (shaping) on decreasing cocaine use and increasing compliance with the prescribed treatment regimens in two health-compromised cocaine-dependent populations: (i) tuberculin (TB) exposed patients (n = 5) and (ii) pregnant women (n = 7). A multiple-baseline across-subjects design was used. There were no contingencies on cocaine use during baseline. During the contingent phase, patients received a monetary reinforcer for (a) successive decreases in the quantity of cocaine and (b) cocaine-free samples. They received a weekly reinforcer if all samples per week met criteria for (a) or (b). During the contingent phase, there was a significant decrease in cocaine metabolite levels and an increase in cocaine-free samples in both populations, with a more robust effect in the TB-exposed group. There was an increase in compliance with prenatal visits among the pregnant women during the contingent phase. Implications for health care are discussed.

Effects of nicotine on cooperative responding among abstinent male smokers.

The effects of nicotine on human cooperative responding in abstinent male smokers were examined. During episodes occurring at random times through a session, concurrently available cooperative and independent responses were maintained by points exchangeable for money. Cooperative responses simultaneously added points to counters marked "Your Earnings" and "Other's Earnings" only if the subject's and another person's responses ostensibly coincided. Independent responses added points only to the counter marked "Your Earnings". After the first daily session abstinent subjects smoked ad libitum, received either 0, 2 or 4mg nicotine gum or abstained from smoking. Increases from this first session in time allocated to the cooperative response option, proportion of cooperative responses and cooperative response rate were significantly greater following ad libitum smoking or acute administration of 4mg nicotine. No effects of nicotine abstinence were observed on independent response rate. These results suggest effects on sociability may maintain nicotine use and increase relapse risk in abstinent smokers.

Effects of ethanol on human free-operant cooperative responding.

The effects of ethanol (0.5, 0.75 and 1.00 g/kg) on human cooperative behavior were examined. Ethanol or placebo was administered 30 min before the second of five trials. During the first of two alternating schedule components, button presses were maintained by a random interval (RI) 60-s schedule of point additions to a counter marked 'Your Earnings'. During the second, Choice, component a concurrent RI 60-s schedule maintained button presses on two manipulanda. Subjects randomly assigned to the social group were instructed that they were paired with another person and could earn points working with or independently of this person. Working together, the cooperative response, simultaneously produced points on counters marked 'Other's Earnings' and 'Your Earnings'. Working independently, the independent response produced points only on the counter marked 'Your Earnings'. The other person was fictitious. The instructions for the non-social group did not mention another subject and the counter marked 'Other's Earnings' was not visible but schedule contingencies were identical to those for the social instruction group. For the social instructions group, 1.00 g/kg ethanol increased the proportion of cooperative responses and time allocated the cooperative option. For the non-social instruction group, time allocated to the topographically identical but non-social equivalent of the cooperative response decreased at the same dose. No significant between-group effects were observed following acute administration of 0.50 and 0.75 g/kg ethanol. These results suggest that the instructions established a functionally distinct social, cooperative, response which was differentially affected by ethanol.

Acute and chronic alcohol tolerance in humans: effects of dose and consecutive days of exposure.

Male social drinkers received doses of either 0.75 or 1.0 g/kg body weight of alcohol over 5 consecutive days. The beverage was divided into three equal drinks, and subjects performed an eye-hand coordination motor task after each drink. The breath alcohol concentration (BAC) was assessed at each performance measurement period. Performance was also assessed when the BAC level on the descending limb of the BAC curve was similar to each of the three BAC measurements on the ascending curve. Each group developed chronic tolerance (comparing the daily postalcohol performance with the daily prealcohol performance) by the 4th day of exposure. The development of a degree of acute tolerance (assessed by comparing the performance on the ascending and descending limbs of the BAC curve) was not observed consistently in the 1.0 g/kg dose group, but was seen in more than half of the subjects in the 0.75 g/kg dose group by the 4th and 5th day of exposure.

Compliance with tuberculosis treatment in methadone-maintained patients: behavioral interventions.

UNLABELLED: Tuberculosis has increased dramatically in the United States. Noncompliance with treatment is high. The purpose of this investigation was to achieve compliance with prophylactic TB treatment and simultaneously decrease drug use in a high-risk group of intravenous drug users. Two studies were conducted. Study 1: Subjects were 9 chronic opiate users who tested positive for tuberculosis and were placed on isoniazid (INH) and methadone. Methadone was dispensed contingent upon INH ingestion throughout. A within-subject, A-B design with contingency management interventions on drug use was implemented. RESULTS: Compliance with INH was 100% in 8 patients. Cocaine use remained high. Study 2: Two patients, meeting same criteria as Study 1, participated in a within-subject A-B multiple baseline design. Methadone was dispensed contingent upon INH ingestion throughout. Successive decreases in cocaine use were reinforced in the contingent phase. RESULTS: Compliance with INH was high. During contingency, both patients had over 40% cocaine-free urine samples compared with 0% at baseline. This investigation serves as a model for achieving compliance with TB treatment in opiate users.

Triazolam and ethanol effects on human matching-to-sample performance vary as a function of pattern size and discriminability.

The effects of placebo, triazolam (2.0, 4.0 and 8.0 micrograms/kg) and ethanol (0.25, 0.5, 1.0 g/kg) on perceptual-motor performance were examined using a visual pattern matching-to-sample procedure in which pattern size and comparison stimulus discriminability were systematically varied. Baseline response rates and accuracy increased as the discriminability of the comparison stimuli increased. At the highest dose, both drugs decreased response accuracy. This disruption of accuracy was attenuated by increasing the discriminability of non-matching stimuli. Triazolam produced dose-related decreases in response rate while ethanol produced only slight decreases at the highest baseline rates of responding. Thus, triazolam produced response rate slowing at relatively lower doses than ethanol.

Acute effects of marijuana smoking on aggressive, escape and point-maintained responding of male drug users.

Aggressive, escape and point-maintained operant responding of male marijuana smokers were measured during six 25-min sessions conducted over an 8-h experimental day. Aggressive responding ostensibly subtracted points exchangeable for money from another subject. Escape responding protected the subject's counter from point subtractions initiated by the other subject for some period of time. Aggressive and escape responding were engendered by subtracting points from the subjects and maintained by initiation of intervals free of point subtractions. Point subtractions presented to the subjects were attributed to other persons. Subjects earned points exchangeable for money on a third response option. Subjects participated in one session prior to smoking and five sessions after smoking. Subjects smoked placebo or three different potencies of active marijuana cigarettes. Marijuana smoking effects on escape responding were not significant and depended upon the frequency of provocation. Point-maintained responding was decreased after marijuana smoking. Aggressive responding was increased for the first hour after smoking and returned to placebo levels later in the day. These effects of marijuana smoking on aggressive responding are discussed in terms of subject characteristics, particularly drug use history.

Effects of response requirement and alcohol on human aggressive responding.

Nine men participated in two experiments to determine the effects of increased response requirement and alcohol administration on free-operant aggressive responding. Two response buttons (A and B) were available. Pressing Button A was maintained by a fixed-ratio 100 schedule of point presentation. Subjects were instructed that completion of each fixed-ratio 10 on Button B resulted in the subtraction of a point from a fictitious second subject. Button B presses were defined as aggressive because they ostensibly resulted in the presentation of an aversive stimulus to another person. Aggressive responses were engendered by a random-time schedule of point loss and were maintained by initiation of intervals free of point loss. Instructions attributed these point losses to Button B presses of the fictitious other subject. In Experiment 1, increasing the ratio requirement on Button B decreased the number of ratios completed in 4 of 5 subjects. In Experiment 2, the effects of placebo and three alcohol doses (0.125, 0.25, and 0.375 g/kg) were determined when Button B presses were maintained at ratio values of 20, 40 and 80. Three subjects who reduced aggressive responding with increasing fixed-ratio values reduced aggressive responding further at higher alcohol doses. One subject who did not reduce aggressive responding with increasing fixed-ratio values increased aggressive responding at the highest alcohol dose. The results of this study support suggestions that alcohol alters aggressive behavior by reducing the control of competing contingencies.

Effects of triazolam on human aggressive, escape and point-maintained responding.

Placebo and triazolam (0.125, 0.25 and 0.5 mg/70 kg of body weight) were administered to male subjects under double-blind conditions prior to experimental sessions which provided three operant response options. These options were: 1) responding maintained by the presentation of points exchangeable for money, 2) responding which ostensibly resulted in the subtraction of points from a fictitious person was termed aggressive since this responding resulted in the delivery of an aversive stimulus to another person, and 3) responding which ostensibly protected the subject's point counter from subtractions initiated by the other person and was termed escape. Aggressive and escape responding were initiated by subtracting points from the subject. Point subtractions were attributed to the other person. Aggressive and escape responding were maintained by initiation of provocation-free intervals (PFI), during which no further point subtractions were presented. Triazolam produced dose-dependent decreases in point-maintained and escape responding. The effects of triazolam on aggressive responding varied across subjects.

Benzodiazepine-induced impairment of matching-to-sample performance in humans.

The effects of benzodiazepines on a visual pattern matching-to-sample (MTS) task were examined in nine healthy male volunteers. The MTS task employed randomly generated checkerboard-like stimuli presented on a video display. The sample and two comparison stimuli were simultaneously presented. Nonmatching comparison stimuli were randomly generated to be 3.125, 6.25, 12.5, 25.0, 37.5, or 50.0 percent different from the sample. Subjects responded on left or right button manipulanda to identify the matching comparison stimulus. The nonmatching stimulus condition was maintained constant for a 60-sec component and the percentage difference of the nonmatching stimuli was systematically varied across multiple components. The effects of triazolam (2.25-9.0 micrograms/kg) and lorazepam (7.5-45 micrograms/kg) were examined in a within-subjects, double-blind, placebo-controlled study. Under placebo conditions, response rates and accuracy were a positive function of the nonmatching stimulus discriminability. Triazolam produced dose-related decreases in response rate at nonmatching stimulus conditions greater than or equal to 25%. Only the 9.0 micrograms/kg dose of triazolam decreased accuracy and this occurred across all nonmatching stimulus conditions. Lorazepam effects were qualitatively similar but less robust than those of triazolam.