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.

Insight and adherence to medication in chronic schizophrenics.

Chronic schizophrenics are well-known for the tendency to not take medication. Clinical observation and studies indicate that insight plays a significant role in medication adherence. This study investigated the roles of insight and perceived benefits from medication by patients. Those patients who had insight, perceived benefits from medication and also perceived a relation between the 2 were more likely to take medication than those who did not have insight nor perceive benefits. A speculative model and possible methods of increasing medication adherence are suggested.

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 acute administration of diazepam and d-amphetamine on aggressive and escape responding of normal male subjects.

Normal males participated in sessions providing two operant response options and were administered either diazepam (study I and II) or d-amphetamine (study II). The acute effects of diazepam on human aggressive responding, which ostensibly subtracted points from another person, were determined in study I. Study II was conducted to determine the extent to which social context and response consequence influenced diazepam (study I) and d-amphetamine (previous research) effects on aggressive responding. In study II, the other response option was escape responding which protected the subject's counter from point losses. Aggressive and escape responding were engendered by subtracting points from the subject's counter, and maintained by initiation of intervals free of point loss. Point subtractions were attributed to the other person (study I) or to a machine (study II). Responding to accumulate points exchangeable for money was available in both studies. Acute diazepam administration decreased aggressive responding in most subjects (study I), slightly increased escape responding (study II), and decreased responding to accumulate points. In study II, d-amphetamine increased both escape responding and responding to accumulate points. The effects of d-amphetamine and diazepam were altered by the instructed source of point loss.

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.

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.

Effects of secobarbital on human aggressive and non-aggressive responding.

This study examined the effects of secobarbital on human aggressive responding in a controlled laboratory setting. Sixty minutes prior to experimental sessions, male subjects were administered either placebo or 50, 100 or 200 mg per 70 kg of body weight doses of secobarbital double-blind. During these sessions, subjects could press a button to accumulate points exchangeable for money (non-aggressive response) or press another button ostensibly to subtract points from a fictitious person (aggressive response). Aggressive responding was occasioned by subtracting points from the subject. Subjects were instructed that points were subtracted by another person. Aggressive responding was maintained by contingent presentation of periods free of point subtractions, i.e., provocations. Acute secobarbital administration produced dose-dependent decreases in non-aggressive responding, and increases in aggressive responding.

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.

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.

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.

Human schedule-induced cardiovascular response.

Sixty-six students were randomly assigned to a vigilance task during which observing responses produced targets according to either a fixed-interval or random-interval 90-sec schedule. During the task, interbeat interval, masseter (EMG) activity, blood pressure and digital blood volume pulse were monitored. Vasoconstriction was initiated within a 4 to 6-sec period following target detection for the majority of subjects assigned to each schedule. Vasomotor tone returned to prechange levels approximately 16 sec after target detection. Transient heart rate increases also occurred during the post-event period, but were more prevalent with subjects in the fixed than in the random-interval group. Post-event masseter activity was exhibited infrequently and only by subjects assigned to the fixed-interval group. The involvement of cardiovascular responsiveness with human schedule-induced behavior and the implications of this involvement for arousal theories of schedule-induced behavior are discussed.

Predictability of repeated challenge: effects on cardiovascular activity in the type A (coronary prone) behavior pattern.

Fifty-two healthy young adults classified either as Type A (coronary prone) or Type B were randomly assigned to a vigilance task during which observing responses produced targets according to either a predictable (i.e., fixed-interval 90-sec) or a nonpredictable (i.e., random-interval 90-sec) reinforcement schedule. During the task, blood volume pulse, interbeat interval, masseter (EMG) activity, and blood pressure were monitored. Transient peripheral vasomotor constriction and heart rate increases were initiated within an 8- to 12-sec period following target detection with the predictable schedule, with subjects evincing greater responsivity than their nonpredictable schedule counterparts. Type A subjects assigned to the random-schedule evinced significantly shorter heart rate and blood volume pulse response durations than did Type B subjects. Longer postevent EMG elevations were evidenced by subjects assigned to the predictable schedule. No significant blood pressure differences were found among the groups. The impact of challenge-contingent behavior on cardiovascular responsivity and the relevance of attentional processes to this relationship and to cardiovascular risk are discussed.

The effects of codeine on human aggressive responding.

Ten healthy male research subjects received placebo, 25, 50 and 75 mg/70 kg of codeine in a controlled laboratory setting. During each session subjects had two response options. The non-aggressive response option was maintained by points exchangeable for ten cents. The aggressive response option ostensibly subtracted a point from the subject's fictitious partner. Aggressive responding was engendered by point subtractions attributed to a fictitious partner. Codeine did not significantly alter the frequency of monetarily reinforced, nonaggressive, responding. Aggressive responding was significantly increased at the 50 mg/70 kg dose of codeine. The frequency of aggressive responses during the placebo sessions preceding administration of the first codeine dose were significantly and positively correlated with scores on the Buss-Durkee Hostility Scale. Aggressive responding increased for four of five subjects scoring below the median on the Buss-Durkee Hostility Scale at the 50 mg/70 kg dose; while administration of 50 mg/70 kg increased aggressive responding of one subject who scored above the median. Aggressive responding for both groups of subjects was unaffected by the 75 mg/70 kg dose.

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.

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.

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.

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.

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.

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.