Do Forgiveness Campaign Activities Improve Forgiveness, Mental Health, and Flourishing?

Objectives: To evaluate the effectiveness of a forgiveness public health intervention at promoting forgiveness, mental health, and flourishing. Methods: Colombian students (N = 2,878) at a private, nonreligious university were exposed to a 4-week forgiveness community campaign and were assessed pre- and post-campaign. Results: Forgiveness, mental health, and flourishing outcomes showed improvements after the campaign. On average, participants reported engaging in 7.18 (SD = 3.99) of the 16 types of campaign activities. The number of types of campaign activities that participants engaged in evidenced a positive linear association with forgiveness, although some activities were more popular than others and some activities were more strongly associated with increased forgiveness. For depression, anxiety, and flourishing, engaging in more activities was generally associated with greater improvements, but the patterns were less consistent relative to forgiveness. Conclusion: This forgiveness public health intervention effectively promoted forgiveness, mental health, and flourishing. Effective campaigns in diverse communities involve promoting mental and physical health through forgiveness. However, recent conflict may hinder acceptance, necessitating political capital for leadership advocating forgiveness initiatives.

Development and Validation of the Forbearance Scale

The character strength of forbearance contributes to peace in broader society, as well as familial harmony. Although forbearance is essential to healthy interpersonal relationships, no psychometrically sound measure has been developed to assess the multi-dimensional nature of forbearance. The present set of studies describes the development and initial validation of the Forbearance Scale (FS). In Study 1, items were generated from focus group interviews with college students (n = 43) to establish the content validity of the scale. In Study 2, the factor structure of the FS was determined using exploratory factor analysis of data from college students (n = 466). In Study 3, the factor structure of the FS was cross-validated with a community sample (n = 579) by means of confirmatory factor analysis. The final scale, the FS-16, consists of 16 items with four factors: (1) emotional calmness, (2) overlook others' misdeeds, (3) tolerance and acceptance, and (4) self-restraint. Hierarchical multiple regression analyses provided evidence of convergent and concurrent validity. The FS-16 demonstrates potential as a new personality assessment tool for measuring forbearance.

Boosting older adults' cognitive functioning and psychological Well-Being through Chinese tea therapy: A preliminary study

OBJECTIVE

To investigate the effect of Chinese tea therapy on the enhancement of cognitive functioning and psychological well-being among older adults in Hong Kong.

METHOD

Seventeen healthy older adults recruited from two senior centers participated in a four-week Chinese tea therapy intervention. Pre-post measures on cognitive functioning and emotional well-being were used to examine the effect of the intervention on cognitive and emotional variables.

RESULTS

Results of the paired samples t-test revealed significant differences between the pre-test and post-test results for cognition and well-being. Specifically, the older adults showed enhanced cognitive functioning and improved emotional well-being after they received the Chinese tea therapy.

CONCLUSION

Chinese tea therapy is apparently an effective strategy to ensure healthy aging. In particular, this innovative and culturally relevant strategy may exert a protective effect against cognitive aging and decline and may boost emotional wellness of older adults in Asian cultures.

The Development and Validation of a Short Form of the Forbearance Scale

The Forbearance Scale (FS) is a 16-item self-report measure of forbearance. In this study, we examined the psychometric properties of the FS subscale and composite scores and developed a 9-item short form of the measure (FS-SF 9). A sample of 1,137 participants was drawn from community, NGO, and college settings. The sample was split into a derivation sample (n = 567) and a validation sample (n = 570). Exploratory factor analyses of the derivation sample data were used to select short-form items. Using the validation sample, confirmatory factor analyses were used to assess fit for proposed item-to-factor assignments. The results of the confirmatory factor analyses supported that the FS-SF 9 had a theoretically congruent factor structure and that all the subscale and composite scores displayed high internal consistency. Correlations with scores from established measures of a lack of forgiveness and emotion regulation also supported the validity of the FS-SF 9. Our data suggest that the FS-SF 9 subscales and composite score retained the psychometric strengths of their longer FS counterparts. Overall, the short form of the FS provides a brief assessment of the construct measured by the full form. Theoretical and practical applications are discussed.

The Role of Self-Regulation in Forgiveness: A Regulatory Model of Forgiveness

Forgiveness is an emotion regulation process that is important for both physical and mental health. Given its benefits, studying the facilitation of forgiveness is important. Researchers have already demonstrated the relationship between self-control and forgiveness. However, in this study, we aim to extend previous research by examining the regulating processes of forgiveness and the possible mediating role of emotion regulation in the relationship between self-regulatory strength and forgiveness. University students (N = 317) in Hong Kong who were recruited to participate in this study completed an online survey. The results of this study indicated that both self-regulatory strength and emotion regulation were significant predictors of forgiveness. Interestingly, cognitive reappraisal significantly mediated the association between self-regulatory fatigue and forgiveness. This suggests a potential self-regulation mechanism that leads to a prorelationship response and provides evidence for a regulatory model of forgiveness.

State narcissism and aggression: The mediating roles of anger and hostile attributional bias

Prior research has documented a relationship between narcissism and aggression but has focused only on dispositional narcissism without considering situational factors that may increase narcissism temporarily. This study explored the possibility that an increase in state narcissism would foster aggressive responding by increasing anger and hostile attributional bias following unexpected provocation among 162 college students from China. We created a guided-imagination manipulation to heighten narcissism and investigated its effects on anger, aroused hostile attribution bias, and aggressive responses following a provocation with a 2 (narcissism/neutral manipulation) × 2 (unexpected provocation/positive evaluation condition) between-subjects design. We found that the manipulation did increase self-reported state narcissism. The increase in state narcissism in turn heightened aggression, and this relation was mediated by increased anger. Regardless of the level of state narcissism, individuals were more aggressive after being provoked and this effect of provocation was mediated by hostile attributional bias. The findings indicate that narcissism can be temporarily heightened in a nonclinical sample of individuals, and that the effect of state narcissism on aggression is mediated by anger. Differences between state and trait narcissism and possible influences of culture are discussed. Aggr. Behav. 42:333-345, 2016. © 2015 Wiley Periodicals, Inc.

Efficacy of REACH Forgiveness across cultures

OBJECTIVE

This study investigates the efficacy of the 6-hour REACH Forgiveness intervention among culturally diverse undergraduates.

METHOD

Female undergraduates (N = 102) and foreign extraction (46.2%) and domestic (43.8%) students in the United States were randomly assigned to immediate treatment or waitlist conditions. Treatment efficacy and the effect of culture on treatment response were assessed using measures of emotional and decisional forgiveness across 3 time periods.

RESULTS

Students in the treatment condition reported greater improvement in emotional forgiveness, but not decisional forgiveness, relative to those in the waitlist condition. Gains were maintained at a 1-week follow-up. Although culture did not moderate the effect of treatment, a main effect of culture on emotional forgiveness and marginally significant interaction effect of culture on decisional forgiveness were found.

CONCLUSION

The REACH Forgiveness intervention was efficacious for college students from different cultural backgrounds when conducted in the United States. However, some evidence may warrant development of culturally adapted forgiveness interventions.

Improving the quality of abstract reporting for economic analyses in oncology

BACKGROUND

The increasing cost of cancer drugs underscores the importance of economic analyses. Although guidelines for abstract reporting of randomized controlled studies and phase i trials are available, similar recommendations for conference abstracts of economic analyses are lacking. Our objectives were to identify items considered to be essential in abstracts of economic analyses;to evaluate the quality of abstracts submitted to the American Society of Clinical Oncology (asco), the American Society of Hematology (ash), and the International Society for Pharmacoeconomics and Outcomes Research (ispor) meetings; andto propose guidelines for future abstract reporting at conferences.

METHODS

Health economic experts were surveyed and asked to rate each of 24 possible abstract elements on a 5-point Likert scale. A scoring system for abstract quality was devised based on elements with an average expert rating of 3.5 or greater. Abstracts for economic analyses from asco, ash, and ispor meetings were reviewed and assigned a quality score.

RESULTS

Of 99 experts, 50 (51%) responded to the survey (average age: 53 years; 78% men; 54% from the United States, 28% from Europe, 18% from Canada). In total, 216 abstracts were reviewed: asco, 53%; ash, 14%; and ispor, 33%. The median quality score was 75, but notable deficiencies were observed. Cost perspective was reported in only 61% of abstracts, and time horizon was described in only 47%. Abstracts from recent years demonstrated better quality scores. We also observed disparities in quality scores for various cancer sites (p = 0.005).

CONCLUSIONS

The quality of conference abstracts for economic analyses in oncology has room for improvement. Abstracts may be enhanced using the guidelines derived from our survey of experts.

Adapting an evidence-based intervention to REACH Forgiveness for different religions and spiritualities

The REACH Forgiveness intervention has been used in psychoeducational groups, couple and individual counseling and psychotherapy, and workbooks. It has been investigated in over 20 randomized clinical trials (RCTs) worldwide. It has been accommodated to treat Christians and shown to be effective in RCTs. But most research has established it to be effective when not accommodating it to religious or spiritual clientele. In this article, we will claim that it can be accommodated to a variety of religious clients. We describe guidelines about what is essential to the treatment and what might be effectively modified to be acceptable to religious and spiritual clients embracing a variety of beliefs and practices.

The differential effects of forms and settings of exposure to violence on adolescents' adjustment

This study investigated the link between exposure to violence and psychosocial adjustment for 442 Chinese secondary school students in Form 1-3. The students completed an inventory assessing exposure to violence through witnessing and through direct victimization in different settings (community, school, and home). Multiple measures and informants (i.e., self-report, teacher report, and school report) were used to assess emotional, behavioral, and cognitive functioning in adolescents. The results of this study showed that overall exposure to violence was related to emotional and behavior problems. High rates of exposure to violence across multiple contexts were found in this sample. After controlling for the co-occurrence of risk factors (e.g., exposure to violence in other settings), both witnessing school violence and being victimized by domestic violence were associated with emotional problems, whereas being victimized by community violence was related to behavior problems. These results suggest that there are differential effects of risks associated with different forms and settings of exposure.

High-speed detection of occult tumor cells in peripheral blood

Although detection of tumor cells in peripheral blood using imitiunocytochemistry and optical scanning is a promising method for screening and monitoring cancer, it poses a major technical challenge due to the extremely low tumor cell concentration in blood. The preferred detection method - digital microscopy - is far too slow for analysis of the large numbers of cells required for statistical validity. We describe here a novel prescan instrument that rapidly identifies a small number of candidates for subsequent examination by digital microscopy to determine if they are genuine tumor cells. The prescan is 500 times faster than digital microscopy and yet has a similar sensitivity. The high prescan speed is accomplished by trading resolution for field of view. The resolution of the prescan is determined by the laser spot size of about 10 microns. While this resolution is much coarser than the submicron resolution of microscopes, it is still sufficient for detecting fluorescent cells because it matches the size of a typical cell. The wide field of view and high scan rate are enabled by a novel application of fiber optics.

Kondo interactions and magnetic correlations in CePt2 nanocrystals

The evolution of the Kondo effect and antiferromagnetic (AF) correlations with size reduction in CePt2 nanoparticles (3.1-26 nm) is studied by analysis of the temperature-dependent specific heat and magnetic susceptibility. The AF correlations diminish with size reduction. The Kondo effect predominates at small particle size with trivalent, small Kondo temperature (TK) magnetic regions coexisting with strongly mixed-valent, large TK nonmagnetic regions. We discuss the role of structural disorder, background density of states and the electronic quantum size effect on the results.

Use of the CRABEL Score for improving surgical case-note quality

INTRODUCTION

Quality assurance of medical record keeping in general surgery is facilitated by use of the CRABEL Score. Critical appraisal and constant feedback to staff plays an important part in improving case-note quality.

MATERIALS AND METHODS

For each case-note audit, a house officer reviewed two sets of case notes for each of six consultant surgeons. Scores were awarded according to initial clerking, subsequent entries, consent, and discharge summary. Overall scores were derived by subtracting deductions for omissions in each category from a starting score of 100. A larger number of points deducted due to absent data leads to a lower overall score and indicates poorer quality case notes. After four audits, a clerking proforma specifically designed to address some of the common areas of weakness identified in our record keeping was introduced and a further audit was performed in March 2004 to assess its impact.

RESULTS

The mean score was lowest in the September 2001 audit and improved over the next two audits. However, there was a small reduction in September 2003 compared to September 2002. When the individual sections of the score were looked at separately, the greatest contribution to a poor score comes from the 'subsequent entries' section since there are five entries scored individually leading to a cumulative effect on the overall score. Within both the 'initial clerking' and 'subsequent entries' sections, early audits showed poor performance across a range of areas but consistent poor implementation of the guidelines was seen in a small number of specific areas as record keeping improved. The quality of medical notes improved over the first three cycles but the improvement was not maintained subsequently.

DISCUSSION

The CRABEL score has been shown to be a useful, reproducible and easy-to-perform objective assessment of the quality of medical record keeping. Repeated audit cycles have ensured that case-note quality remains a high priority and have also led to the development of standardised admission documentation. Introduction of the latter has led to a measurable improvement in medical record keeping.

Development and inter-rater reliability of a standardized verbal instruction manual for the Chinese Geriatric Depression Scale-short form

The Geriatric Depression Scale (GDS) is a common screening tool for elderly depression in Hong Kong. This study aimed at (1) developing a standardized manual for the verbal administration and scoring of the GDS-SF, and (2) comparing the inter-rater reliability between the standardized and non-standardized verbal administration of GDS-SF. Two studies were reported. In Study 1, the process of developing the manual was described. In Study 2, we compared the inter-rater reliabilities of GDS-SF scores using the standardized verbal instructions and the traditional non-standardized administration. Results of Study 2 indicated that the standardized procedure in verbal administration and scoring improved the inter-rater reliabilities of GDS-SF.

SB-242235, a selective inhibitor of p38 mitogen-activated protein kinase. II: in vitro and in vivo metabolism studies and pharmacokinetic extrapolation to man

1. Inhibition of p38 MAP kinase has been investigated extensively as a potential therapy for cytokine-mediated diseases such as autoimmune and inflammatory diseases. SB-242235 (1-(4-piperidinyl)-4-(4-fluorophenyl)-5-(2-methoxy-4-pyrimidinyl) imidazole) is a potent and selective p38 MAP kinase inhibitor; the preclinical pharmacokinetics of SB-242235 have been described previously. The present studies were conducted to describe the in vitro metabolic rates and routes of SB-242235 metabolism, to characterize its in vivo preclinical metabolism, and to use these data to aid in the prediction of the pharmacokinetic behaviour of SB-242235 in man. 2. SB-242235 was metabolically stable in rat, dog, monkey and human hepatic microsomes, isolated hepatocytes and liver slices in vitro. The in vivo preclinical metabolism studies were consistent with the in vitro findings; SB-242235 was minimally metabolized, and was primarily excreted unchanged in the urine (45 and 67% of the administered dose in the rat and monkey, respectively). 3. Allometric scaling using various correction factors predicted that SB-242235 would have low clearance in man with a predicted half-life ranging from 11.5 to 18.7h. This prediction was consistent with the observed mean half-life of 16.4h in the first-in-man study for SB-242235. An allometric scaling method with a correction for interspecies differences in glomerular filtration rate provided the most accurate prediction of the pharmacokinetic behaviour of SB-242235 in humans, although the clinical data also highlight potential difficulties in conducting prospective allometry.

Failure of central 5-hydroxytryptamine depletion to alter the effect of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on timing performance on the free-operant psychophysical procedure

RATIONALE

The 5-hydroxytryptamine (5-HT)(1A) receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) alters temporal differentiation of behaviour on the free-operant psychophysical procedure, displacing the psychophysical curve to the left, thereby reducing the indifference point T(50). However, it is not known whether this effect of 8-OH-DPAT is mediated by an action of the drug at somatodendritic autoreceptors or at postsynaptic receptors.

OBJECTIVE

To compare the effects of 8-OH-DPAT on performance on the free-operant psychophysical procedure in normal (sham-lesioned) rats and in rats whose 5-HTergic pathways had been lesioned by means of intra-raphe injections of the selective neurotoxin 5,7-dihydroxytryptamine (5,7-DHT).

METHODS

Twelve rats received 5,7-DHT-induced lesions of the median and dorsal raphe nuclei, and twelve received sham lesions. They were trained under the free-operant psychophysical procedure to press two levers (A and B) in 50-s trials, during which reinforcement was provided intermittently for responding on A in the first half and B in the second half of the trial. Percentage responding on B (%B) was recorded in successive 5-s epochs of the trials; logistic psychophysical curves were fitted to the data from each rat for the derivation of timing indices [T(50) (time corresponding to %B=50%) and Weber fraction] following treatment with acute doses of 8-OH-DPAT (25, 50, 100, 200 microg kg(-1), s.c.) and saline (vehicle-alone treatment). Levels of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), noradrenaline and dopamine were measured in forebrain regions after the completion of the experiment.

RESULTS

Under the vehicle-alone condition, the lesioned group displayed a greater propensity for switching between the levers, but T(50) and the Weber fraction did not differ between the groups. In both groups, 8-OH-DPAT shifted the psychophysical curve to the left, significantly reducing T(50) at the 200-microg kg(-1) dose; the effect of 8-OH-DPAT did not differ significantly between the groups. Levels of 5-HT and 5-HIAA in the lesioned group were about 10% of those in the sham-lesioned group; there was no effect of the lesion on catecholamine levels.

CONCLUSIONS

The results confirm that 8-OH-DPAT disrupts temporal differentiation in the free-operant psychophysical schedule, reducing the indifference time, T(50). The failure of central 5-HT depletion to alter the effect of 8-OH-DPAT suggests that this effect may be mediated by stimulation of postsynaptic 5-HT(1A) (or possibly 5-HT(7)) receptors rather than somatodendritic 5-HT(1A) autoreceptors.

Examination of the best pressure range for ion/molecule reactions of anthraquinones in an external source ion trap mass spectrometer

This study outlines some observations of the pressure effect for gas phase ion-molecule reactions of anthraquinone derivatives with dimethyl ether in an external source ion trap mass spectrometer. At the reagent pressure of 7.998 x 10(-2) Pa, formation of the protonated ions, [M + 13]+, [M + 15]+, and [M + 45]+ ions, of anthraquinones can be observed. However, at the pressure of 1.066 x 10(-2) Pa, formation of molecular ions and many fragment ions of the M+. or [M + H]+ ions have been observed. Since the pressure effect is notable within a small range of pressures for many compounds, it is important to draw attention to the use of the ion trap with an external source where other factors such as ion source residence time may play a role. This can also provide some information for better and more careful controls of the reagent pressure in order to obtain fair CI spectra in an external source ion trap mass spectrometer.

Selective self-ion/molecule reactions in both external and internal source ion trap mass spectrometers

Novel results on the selective self-ion/molecule reactions (SSIMR) in both external and internal source ion trap mass spectrometers are demonstrated. Selective self-ion/molecule reaction product ions were produced between the oxygenated and nitrogenated crown ethers. For the oxygenated crown ethers, self-ion/molecule reactions lead to the formation of the protonated ions, adduct ions of fragments ([M + F](+)) and [M + H(3)O](+), while the nitrogenated crown ethers produce [M + H](+), [M + CH](+) and [M + C(2)H(3)](+) ions.

Effects of central 5-hydroxytryptamine depletion on sensitivity to delayed and probabilistic reinforcement

RATIONALE

The ascending 5-hydroxytryptaminergic (5-HTergic) pathways are believed to be involved in "impulse control". Rats whose 5-HTergic pathways have been destroyed are more liable than intact rats to select a smaller, immediate reinforcer rather than a larger, delayed reinforcer (impulsive choice), and recent evidence indicates that this effect of central 5-HT depletion reflects a change in the rate of time discounting (i.e. a change in the rate at which reinforcers become devalued as a function of delay). Delay of reinforcement and uncertainty of reinforcer delivery are believed to have equivalent effects on choice behaviour. However, it is not known whether central 5-HT depletion affects choice between probabilistic reinforcers.

OBJECTIVE

We examined the effects of central 5-HT depletion on choice behaviour in two experiments: In experiment 1, rats chose between a smaller immediate reinforcer and a larger delayed reinforcer; in experiment 2, rats chose between a smaller certain reinforcer and a larger probabilistic reinforcer.

METHODS

Rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press two levers for food-pellet reinforcers in discrete-trials schedules. In free-choice trials, selection of lever A resulted in immediate delivery of one food pellet; selection of lever B resulted in delivery of 2 pellets, either following a delay (dB) (experiment 1) or with a probability (pB) less than 1 (experiment 2).

RESULTS

In experiment 1, both groups showed declining choice of lever B (%B) as a function of dB. The lesioned group showed shorter indifference delays (D50: the value of dB corresponding to %B=50) than the sham-lesioned group. In experiment 2, both groups showed declining choice of lever B as a function of the odds against delivery of the two-pellet reinforcer, thetaB (thetaB=[1/pB]-1). There was no difference between the "indifference odds" (theta50: the value of thetaB corresponding to %B=50) between the two groups. In both experiments, the levels of 5-HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered.

CONCLUSIONS

These results provide additional evidence that central 5-HTergic mechanisms are involved in time discounting, but provide no evidence for a similar role of 5-HT in rats' sensitivity to probabilistic reinforcement.

Effects of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on performance on two operant timing schedules

RATIONALE

Previous experiments have shown that the disruptive effect of central 5-HT depletion on interval timing behaviour is critically dependent upon the particular timing schedule used. However, it is not known how acute disruption of 5-HTergic function brought about by drugs acting at 5-HT receptors affects timing.

OBJECTIVE

To examine the effects of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on performance on two quantitative timing schedules, a free-operant schedule in which rats were trained to distribute their responses differentially between two levers during the course of a 50-s trial (free-operant psychophysical procedure) and a discrete-trials schedule in which rats were trained to discriminate the durations of light stimuli (interval bisection task).

METHODS

In experiment 1, rats were trained under the free-operant psychophysical procedure to respond on two levers (A and B) in 50-s trials in which reinforcement was provided intermittently for responding on A in the first half, and B in the second half, of the trial. For one group, repetitive switching between levers was permitted; for another group, it was prevented. In experiment 2, rats were trained to press lever A after a 2-s stimulus and lever B after an 8-s stimulus, and were then tested with stimuli of intermediate durations. For one group, a 'poke response' (depression of a central tray flap) was required after stimulus presentation to effect lever presentation; for the other group this requirement did not operate. In both experiments, quantitative indices of timing were derived from the psychophysical functions (%B responding vs time).

RESULTS

In experiment 1, 8-OH-DPAT (25, 50, 100 and 200 microg kg(-1) s.c.) displaced the psychophysical curve to the left in both versions of the schedule. In experiment 2, 8-OH-DPAT increased the Weber fraction in both versions of the task without displacing the curve.

CONCLUSIONS

These results show that 8-OH-DPAT disrupts timing behaviour. The results of experiment 1 are consistent with the proposal that 5-HTergic mechanisms help to regulate the period of the hypothetical pacemaker. However, the results of experiment 2 do not support this suggestion. Taken together, the results support the notion that different neural mechanisms may be involved in timing tasks involving temporal distribution of responding and discrimination of the durations of exteroceptive stimuli.

Comparison of the effects of clozapine, haloperidol, chlorpromazine and d-amphetamine on performance on a time-constrained progressive ratio schedule and on locomotor behaviour in the rat

Performance on progressive ratio schedules has been proposed as a means of assessing the effects of drugs on "reinforcer efficacy". It has been proposed that the effects of neuroleptic drugs on operant behaviour are mediated by a reduction of "reinforcer efficacy". We examined the effects of two "conventional" neuroleptics (haloperidol and chlorpromazine) and an "atypical" neuroleptic (clozapine) on progressive ratio schedule performance; d-amphetamine was used as a comparison compound. In experiment 1, rats responded for a sucrose reinforcer on a time-constrained progressive ratio schedule (75-min sessions). After 66 preliminary training sessions, the rats received single doses (IP) of haloperidol (0.05, 0.1 mg kg(-1)). chlorpromazine (2, 4 mg kg(-1)), clozapine (0.5, 1, 2, 4, 8 mg kg(-1)), and d-amphetamine (0.2, 0.4, 0.8 mg kg(-1)), and the corresponding vehicle solutions. The highest ratio completed was reduced by haloperidol and chlorpromazine, and increased by clozapine. All three neuroleptics reduced the peak response rate, at least at the highest doses administered. Response rates on the lower and intermediate ratios could be described by a three-parameter equation proposed to account for fixed ratio schedule performance. Haloperidol reduced, and clozapine dose-dependently increased the "motivational" parameter (a); d-amphetamine reduced it at low doses and increased it at high doses. The three neuroleptics increased the "response time" parameter (delta). Un-reinforced locomotor behaviour, measured in experiment 2, was not significantly altered by haloperidol, chlorpromazine or clozapine, but was increased by d-amphetamine. These results are consistent with a reduction of reinforcer efficacy produced by haloperidol and an increase produced by clozapine; clozapine's effect is unlikely to reflect a general increase in locomotion. All three neuroleptics induced some degree of motor debilitation. The quantitative analysis of progressive ratio schedule performance may provide a useful adjunct to existing methods for separating effects of drugs on motivational and motor processes.

The effect of d-amphetamine on performance on two operant timing schedules

RATIONALE

Previous experiments have shown that d-amphetamine disrupts timing behaviour in rats. It has been proposed that d-amphetamine's effects reflect a reduction in the period of the pacemaker of the hypothetical internal clock. However, some studies have obtained conflicting results.

OBJECTIVE

To examine the effects of d-amphetamine (0.2, 0.4, 0.8 mg kg(-1) i.p.) on performance on two quantitative timing schedules: a free-operant schedule, in which rats were trained to distribute their responses differentially between two levers during the course of a 50-s trial (free-operant psychophysical procedure), and a discrete-trials schedule, in which rats were trained to discriminate the duration of light stimuli (interval bisection task).

METHODS

In experiment 1, rats were trained under the free-operant psychophysical procedure to respond on two levers (A and B) in 50-s trials in which reinforcement was provided intermittently for responding on A during the first half and on B during the second half of the trial. For one group, repetitive switching between levers was permitted; for another group, it was prevented. In experiment 2, rats were exposed to press lever A after a 2-s stimulus and lever B after an 8-s stimulus, and were then tested with stimuli of intermediate duration. For one group, a 'poke response' (depression of a central tray flap) was required after stimulus presentation to effect lever presentation; for the other group, this requirement did not operate. In both experiments, quantitative indices of timing were derived from the psychophysical functions (%B responding vs time).

RESULTS

In experiment 1, d-amphetamine increased the Weber fraction and displaced the psychophysical curve to the left in both versions of the schedule, as well as producing rate-dependent suppression of responding. In experiment 2, d-amphetamine increased the Weber fraction in both versions of the task without displacing the curve.

CONCLUSIONS

These results confirm the disruptive effect of d-amphetamine on timing. The results of experiment 1 are consistent with the proposal that the drug reduces the period of the hypothetical pacemaker. However, the results of experiment 2 do not support this suggestion. Taken together, the results support the notion that different neural mechanisms may be involved in timing tasks involving temporal distribution of responding and discrimination of the duration of exteroceptive stimuli.

Effect of central 5-hydroxytryptamine depletion on inter-temporal choice: a quantitative analysis

RATIONALE

It has been proposed that the ascending 5-hydroxytryptaminergic (5-HTergic) pathways are involved in "impulse control". Previous experiments have shown that rats whose 5-HTergic pathways have been destroyed are more liable than intact rats to select a smaller, immediate reinforcer rather than a larger, delayed reinforcer (impulsive choice). However, it remains unclear whether this effect of central 5-HT depletion reflects a change in the rate of time discounting (i.e. a change in the rate at which reinforcers become devalued as a function of delay) or a change in sensitivity to reinforcer size.

OBJECTIVE

We examined the effect of central 5-HT depletion on time discounting using a quantitative model of inter-temporal choice (multiplicative hyperbolic model), which enables effects on time discounting to be differentiated from effects on sensitivity to reinforcer size.

METHODS

Rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press two levers for food-pellet reinforcers in a discrete-trials adjusting-delay schedule. In free-choice trials, selection of lever A resulted in a brief fixed delay (dA) followed by delivery of one pellet; selection of lever B resulted in a longer variable delay (dB) followed by delivery of two pellets; dB was adjusted in accordance with the subject's choices. The value of dA was varied (0.5-8.0 s) in successive phases of the experiment, and the indifference value of dB was determined in each case.

RESULTS

In both groups, the indifference value of dB was linearly related to the value of dA, in accordance with the multiplicative hyperbolic model. The lesioned group showed shorter indifference delays than the sham-lesioned group, this being reflected in a parallel displacement of the linear indifference function. In both experiments, the levels of 5-HT and 5-hydroxyindole-acetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered.

CONCLUSIONS

According to the multiplicative hyperbolic model, parallel displacement of the linear indifference function uniquely specifies a change in time discounting. Thus these results indicate that central 5-HT depletion results in an increase in the rate of time discounting for food reinforcers.

Theory and method in the quantitative analysis of "impulsive choice" behaviour: implications for psychopharmacology

Impulsive choice refers to the selection of small immediate gains in preference to larger delayed gains, or the selection of large delayed penalties in preference to smaller immediate penalties. Current theoretical interpretations of impulsive choice are reviewed, and a synthesis of these ideas, the "multiplicative hyperbolic model of choice", is presented. The model assumes that the value of a positive reinforcer increases as a hyperbolic function of its size, and decreases as a hyperbolic function of its delay and the odds against its occurrence. Each hyperbolic function contains a single discounting parameter which quantifies the organism's sensitivity to the variable in question. The hyperbolic discounting functions combine multiplicatively to determine the overall value of the reinforcer. Equivalent functions are postulated to govern the (negative) value of aversive events, the net value of an outcome reflecting the algebraic sum of the positive and negative values. The model gives rise to a quantitative methodology for studying impulsive choice, based on a family of linear indifference (null) equations, which describe performance under conditions of indifference, when the values of the reinforcers are assumed to be equal. This methodology may be used to identify individual differences in sensitivity to the magnitude, delay and probability of reinforcement. The methodology is also suitable for the quantitative evaluation of the effects of some pharmacological interventions on discounting parameters. Recent psychopharmacological studies of impulsive choice are reviewed, and the utility of indifference equations for extending this work, and developing a quantitative psychopharmacology of impulsive choice is discussed.

Interval timing performance in temporal lobe epilepsy: differences between patients with left and right hemisphere foci

This experiment examined interval timing performance on a temporal reproduction procedure and a temporal discrimination (interval bisection) procedure in 19 patients with temporal lobe epilepsy (ten with a left-hemisphere focus [LTE group] and nine with a right- hemisphere focus [RTE group]), and 14 normal control subjects. In the temporal reproduction task, subjects were required to reproduce the durations of visual stimuli (0.5, 1, 2, 4, 8 s). In the temporal discrimination task, subjects were required to classify the visual stimuli as either 'short' or 'long'. Following exposure to the two standard durations (1 and 2 s), 'probe' trials were introduced in which the stimulus was presented for durations intermediate between the two standard durations. Psychophysical functions were derived from both timing tasks for each individual subject, as well as for the group mean data. The results showed that, compared to the normal subjects, the RTE group's timing ability was significantly compromized, as reflected by larger Weber fractions in both timing tasks. The LTE group's Weber fractions did not differ significantly from those of the control group; however they showed a leftward shift (i.e. a shorter bisection point) of the psychophysical function under the temporal discrimination task. The results suggest that the right and left hemispheres may play different roles in regulating interval timing performance.

Effect of central 5-hydroxytryptamine depletion on changeover behaviour in concurrent schedules of reinforcement

RATIONALE

Previous experiments have shown that rats whose 5-hydroxytryptaminergic (5-HTergic) pathways have been destroyed exhibit higher rates of switching between response alternatives on various temporal differentiation schedules.

OBJECTIVE

This paper reports two experiments investigating the effect of central 5-HT depletion on switching between concurrent schedules of reinforcement which do not entail temporal differentiation of behaviour.

METHODS

Rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press levers for sucrose reinforcement. In experiment 1, the rats were exposed to concurrent pairs of variable-time (VT) schedules specifying equal inter-reinforcement intervals; responses on a single "changeover lever" alternated between the two VT schedules. In experiment 2, the rats were exposed to concurrent pairs of variable-interval (VI) schedules specifying equal inter-reinforcement intervals; responses on one lever ("VI lever") earned reinforcers, while responses on the other lever ("changeover lever") alternated between the two VI schedules.

RESULTS

In experiment 1, both groups showed longer "dwell-times" (intervals between successive changeover responses) when a reinforcer was delivered in the "dwell" than when no reinforcer was delivered ("win-stay" effect). The lesioned rats showed higher rates of changeover responding and shorter dwell-times (with and without reinforcer delivery) than the sham-lesioned group. In experiment 2, the rate of responding on the VI lever did not differ significantly between the two groups; however, the lesioned rats showed higher rates of changeover responding, shorter dwell-times (with and without reinforcer delivery) and smaller numbers of inter-changeover responses on the VI lever than the sham-lesioned group. In both experiments, the levels of 5-HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered.

CONCLUSIONS

These results provide further evidence for the involvement of the ascending 5-HTergic pathways in behavioural "switching", and indicate that this is not restricted to temporal differentiation schedules.

Effect of central 5-hydroxytryptamine depletion on performance in the free-operant psychophysical procedure: facilitation of switching, but no effect on temporal differentiation of responding

This experiment examined the effect of destroying the ascending 5-hydroxytryptaminergic (5-HTergic) pathways on timing and switching behaviour in the free-operant psychophysical procedure. Rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press levers for sucrose reinforcement; sessions consisted of fifty 50-s trials in which reinforcers were available on a variable-interval 30-s schedule. In the first 25 s, of each trial, reinforcement was only available for responses on lever A; in the last 25 s, it was available only for responses on lever B. In phase 1 (70 sessions) repetitive switching between the levers was prevented by withdrawal of lever A after the first response on lever B in each trial; in phase 2 (40 sessions) this constraint on switching was removed; in phase 3 (40 sessions) the constraint was reinstated. Data were collected from probe trials (four per session) in which no reinforcers were delivered, during the last ten sessions of each phase. In all phases, both groups showed declining response rates on lever A and increasing response rates on lever B as a function of time from the onset of the trial. Response rate on lever B, expressed as percentage of overall response rate, could be described by a two-parameter logistic function. Removal of the constraint on switching reduced the slope of the function without changing the indifference point (time corresponding to 50% responding on lever B). The parameters of the timing function did not differ between the groups in any of the phases. However, the lesioned group showed a greater enhancement of switching rate during phase 2 than the control group. The levels of 5-HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered. The results provide further evidence for the involvement of the ascending 5-HTergic pathways in switching between response alternatives, but cast doubt on our previous suggestion that the effects of 5-HT depletion on temporal differentiation of behaviour are mediated by facilitated switching.

Group B Streptococcal infection in neonates: an 11-year review

Group B Streptococcal (GBS) infection is an important cause of infant morbidity and mortality. The purpose of this study is to evaluate the incidence, clinical characteristics, mortality and complications of this infection. From 1985 through 1995, 66 infants with early onset disease (EOD) and 23 infants with late onset disease (LOD) were treated at Mackay Memorial Hospital (MMH). The occurrence rate of EOD was 3.26-10.08/1000 admissions. The incidence of the disease was 0.11-1.39/1000 live births. Of the 66 EOD infants, 24 (36%) were preterm infants. There were 33 (50%) infants in EOD category with respiratory distress and 40 (60%) infants with sepsis. Among the 23 LOD infants, 3 (13%) were preterm infants. There were 6 (13%) infants in LOD category with respiratory distress and 16 (69%) with sepsis. Nine (13%) EOD infants and 14 (60%) LOD infants had meningitis. Leukopenia occurred in 24 (36%) EOD infants and 5 (21%) LOD infants. Twelve (18%) EOD infants and 9 (39%) LOD infants had a history of prolonged rupture of membrane (PROM). The mortality rate was 14% in EOD and 4% in LOD infants. Four (17%) LOD infants developed neurological seguelae. Clinically, EOD infants were often premature and prone to develop sepsis, respiratory distress and leukopenia, while LOD often presented with meningitis and sepsis. Our estimated occurrence rate and incidence of EOD were similar to the European estimates. The influence of prenatal measures on EOD and the meaning of PROM on LOD need further evaluation.

Effect of central 5-hydroxytryptamine depletion on tolerance of delay of reinforcement: evidence from performance in a discrete-trials "time-left" procedure

This experiment examined the effect of destruction of the ascending 5-hydroxytryptaminergic (5HTergic) pathways on performance on a new discrete-trials version of the "time-left" procedure. Rats received either injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained in a discrete trials schedule in which reinforcers were provided for responding on either of two levers, A and B. At a random time point, t s after the start of each trial, the two levers were inserted into the operant chamber: a response on A resulted in the delivery of one food pellet after dA s, whereas a response on B resulted in the delivery of two pellets after 84-t s. The value of dA was varied between 1 and 12 s in different phases of the experiment. Both groups showed an increasing tendency to respond on lever B as a function of time within the trial. Logistic functions were fitted to the data from each group, and a value of the "indifference point" (T50: the time within the trial at which proportional choice of B attained a value of 50%) was derived for each rat. For each value of dA, the values of T50 were significantly greater in the lesioned rats than in the control rats, reflecting a rightward shift of the logistic function in the lesioned group. The levels of 5HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not significantly altered. The results provide further evidence for the involvement of the ascending 5HTergic pathways in the control of operant behaviour by delayed positive reinforcers.

5-hydroxytryptamine and impulse control: prospects for a behavioural analysis

Impulsiveness is a significant clinical problem associated with a variety of psychiatric and neuropsychiatric disorders. Clinical and experimental studies have provided evidence that individuals displaying impulsive behaviour tend to show signs of deficient functioning of the ascending 5-hydroxytryptaminergic (5-HTergic) pathways of the brain. A persistent problem in investigations of the biological basis of impulsive behaviour has been the lack of a satisfactory definition of 'impulsiveness', as distinct from other behavioural features, such as aggression, which are often apparent in 'impulsive' individuals. Research in the experimental analysis of behaviour suggests that two important characteristics of 'impulsiveness' are (i) deficient tolerance of delay of gratification and (ii) inability to inhibit or delay voluntary behaviour; both of these characteristics are amenable to study in laboratory animals. We describe some delayed reinforcement and delayed response paradigms which purport to capture these behavioural characteristics, and review recent evidence that manipulation of 5-HTergic function alters behaviour in these paradigms. It is argued that the two characteristics of 'impulsiveness' are themselves the product of disturbance of more fundamental behavioural processes; the nature of these processes is considered.

Effect of destruction of noradrenergic neurones with DSP4 on performance on a free-operant timing schedule

This experiment examined the effect of destroying central noradrenergic neurones, using the selective neurotoxin DSP4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine], on performance in a free-operant timing schedule. Rats received either systemic treatment with DSP4 or vehicle-alone injections. They were trained to press levers for a sucrose reinforcer. Training sessions consisted of 40, 50-s trials in which reinforcers were available on a variable-interval 25-s schedule; in the first 25 s of each trial, reinforcers were only available for responses on lever A, whereas in the last 25 s reinforcers were available only for responses on lever B. Data were collected from probe trials (four per session), in which no reinforcers were delivered, during the last ten of 60 training sessions. Both groups showed decreasing response rates on lever A, and increasing response rates on lever B, as a function of time from the onset of the trial. Quantitative indices of timing behaviour were derived from a two-parameter logistic function fitted to the relative response rates on lever B (response rate on lever B, expressed as a percentage of overall response rate); this function accounted for > 90% of the data variance in each group. The DSP4-treated group showed a significantly lower value of the indifference point (i.e. the time corresponding to 50% responding on lever B) than the control group. The slope of the function and the rate of switching between response alternatives did not differ significantly between the two groups. The concentrations of noradrenaline were markedly reduced in the neocortex and hippocampus of the DSP4-treated group, but the concentrations of dopamine, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid were not significantly altered. It is suggested that results may be consistent with a role of the dorsal ascending noradrenergic pathway in behavioural "arousal".

A bovine oxytocin transgene in mice: expression in the female reproductive organs and regulation during pregnancy, parturition and lactation

Transgene bovine oxytocin 3.5 (bOT3.5) consists of the bovine oxytocin structural gene flanked by 0.6 kbp of upstream and 1.9 kbp of downstream sequences. We have examined the expression of bOT3.5 in the female reproductive organs, and we show tissue-specific and physiological regulation dependent on the stage of pregnancy and lactation. In the ovary, no transgene expression could be detected during the estrus cycle, or during pregnancy. However, high levels of transgene RNA were found at day 1 of lactation. Expression dropped 10-fold by day 2 of lactation, and was undetectable thereafter. Interestingly, the expression of bOT3.5 in the mouse ovary at the beginning of lactation mimics that of the endogenous OT gene in the bovine ovary. Expression of the bOT3.5 transgene correlates with a parturition defect that results in considerable maternal mortality.

Effect of central 5-hydroxytryptamine depletion on performance in the "time-left" procedure: further evidence for a role of the 5-hydroxytryptaminergic pathways in behavioural "switching"

This experiment examined the effect of destruction of the ascending 5-hydroxytryptaminergic (5HTergic) pathways on performance in a free-operant timing schedule: the "time-left" procedure. Rats received either injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained in a discrete trials schedule in which reinforcers were provided for responding on either of two levers, A and B. At a random time point, t s after the start of each trial, a response on A resulted in the delivery of one food pellet after dA s, whereas a response on B resulted in the delivery of two pellets after 60-t s. The value of dA was varied between 1 and 8 s in different phases of the experiment. Both groups showed decreasing response rates on lever A and increasing response rates on lever B as a function of time within the trial. An index of timing (T75: the time within the trial at which relative response rate on B attained a value of 75%) was systematically related to the value of dA, but did not differ significantly between lesioned and control rats. However, the lesioned group showed significantly higher rates of switching between response alternatives than the sham-lesioned group at all values of dA. The levels of 5HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not significantly altered. The results provide further evidence that the ascending 5HTergic pathways may contribute to the inhibitory regulation of switching between behavioural states.

Repression of vasopressin gene expression by glucocorticoids in transgenic mice: evidence of a direct mechanism mediated by proximal 5' flanking sequence

Glucocorticoids are known to exert multiple effects upon neuronal systems and neuronal gene expression but the molecular mechanisms through which these effects are mediated are largely undefined. In this study, a transgenic mouse model that expresses a bovine vasopressin transgene was used to investigate the mechanisms by which this neuropeptide gene is repressed by glucocorticoids. Using both northern analysis and a reverse transcriptase polymerase chain reaction assay, depletion of glucocorticoids with the 11,beta-hydroxylase inhibitor metyrapone was shown to result in a dexamethasone-reversed increase in ectopic adrenal transgene messenger RNA levels. This result shows that sequences within the confines of the 3.5 kb transgene are sufficient to mediate repression by glucocorticoids, and indicates the involvement of a type II glucocorticoid receptor mechanism which is independent of cellular context. Evidence for the involvement of cis-acting repressive elements in the proximal 5' flanking sequence was obtained in further studies in which bovine transgene constructs were shown to be negatively regulated by dexamethasone in 293 cells. The further demonstration that recombinant glucocorticoid receptor binds to a vasopressin promoter fragment in an in vitro electrophoretic mobility shift assay provided additional evidence of a direct mechanism of repression. Both in vitro studies were consistent with the presence of a glucocorticoid regulatory element within the region -300 to 155 of the transcription start site. The use of an in vivo transgenic system combined with in vitro analyses of gene promoter fragments enabled the characterization of the molecular mechanisms which effect physiological changes in vasopressin gene expression, and provided evidence of a direct mechanism of repression mediated by sequences within the vasopressin gene promoter.

Destruction of central noradrenergic neurones with DSP4 impairs the acquisition of temporal discrimination but does not affect memory for duration in a delayed conditional discrimination task

This experiment examined the effect of destroying central noradrenergic neurones using the selective neurotoxin N-(2-chloroethyl)-n-ethyl-2-bromobenzylamine (DSP4) on the acquisition of a temporal discrimination and on memory for duration, using a delayed conditional discrimination task. In phase I, rats that had received systemic treatment with DSP4 and vehicle-treated control rats were trained in a series of discrete trials to press lever A following a 2-s presentation of a light stimulus, and lever B following an 8-s presentation of the same stimulus. Following stimulus offset, a response on a panel placed midway between the two levers was required to initiate lever presentation; a single response on either lever resulted in withdrawal of both levers and, in the case of a "correct" response, reinforcer delivery. Both groups acquired accurate discrimination, achieving 90% correct choices within 50 sessions; the DSP4-treated group acquired accurate performance more slowly than the control group. In phase II, delays were interposed between stimulus offset and lever presentation in 50% of the trials. In the absence of a delay, discriminative accuracy was lower in the DSP4-treated group than in the control group. Accuracy declined as a function of post-stimulus delay in both groups; both groups showed a delay-dependent bias towards responding on lever A ("choose-short" bias). Neither of these effects differed significantly between the two groups. The concentrations of noradrenaline in the parietal cortex and hippocampus were reduced by 90% and 89% in the DSP4-treated group, compared to the levels in the control group, but the levels of dopamine, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid did not differ significantly between the groups. The results confirm the deleterious effect of DSP4 on the acquisition of temporal discrimination, but do not provide evidence for a role of the noradrenergic innervation of the hippocampus and neocortex in temporal working memory.

Inhibition of bradykinin-induced calcium increase by phosphatase inhibitors in neuroblastoma x glioma hybrid NG108-15 cells

Prior treatment of NG108-15 cells with phosphatase inhibitors including okadaic acid and calyculin A inhibited the elevation of cytosolic Ca2+ concentration ([Ca2+]i) induced by bradykinin by approximately 63%. This inhibition was dependent on the concentration of okadaic acid with an IC50 of 0.15 nM. Okadaic acid treatment only lowered the maximal response of [Ca2+]i increase and had no effect on the EC50 value for bradykinin regardless of the presence of extracellular Ca2+. Neither the capacity of 45Ca2+ accumulation within intracellular nonmitochondrial Ca2+ stores nor the magnitude of [Ca2+]i increase induced by thapsigargin was reduced by the treatment of okadaic acid. In contrast, the same phosphatase inhibitor treatment inhibited the bradykinin-evoked inositol 1,4,5-trisphosphate (IP3) generation, the Mn2+ influx, and the capacity of mitochondrial Ca2+ accumulation. Furthermore, the sensitivity of IP3 in the Ca2+ release was suppressed by okadaic acid pretreatment. Our results suggest that the reduction of bradykinin-induced [Ca2+]i rise by the promotion of protein phosphorylation was attributed to the reduced activity of phospholipase C, the decreased sensitivity to IP3, and the slowed rate of Ca2+ influx. Thus, phosphorylation plays a role in bradykinin-sensitive Ca2+ signaling cascade in NG108-15 cells.

Effect of destruction of the 5-hydroxytryptaminergic pathways on temporal memory: quantitative analysis with a delayed interval bisection task

This experiment examined the effect of destruction of the ascending 5-hydroxytryptaminergic (5HTergic) pathways on memory for duration, using a delayed interval bisection task. Rats that had received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei, and sham-lesioned control rats, were trained in a series of discrete trials to press lever A following a 2-s presentation of a light stimulus, and lever B following an 8-s presentation of the same stimulus. Following stimulus offset a response on a panel placed midway between the two levers was required in order to initiate lever presentation; a single response on either lever resulted in withdrawal of both levers and, in the case of a "correct' response, reinforcer delivery. When > 90% correct choices had been attained, an 8-s (phase I) or a 12-s (phase II) delay was interposed between stimulus offset and lever presentation in 50% of the trials, and probe trials (10% of both non-delay and delay trials) were introduced in which the light was presented for intermediate durations. Logistic functions were derived relating percent choice of lever B to stimulus duration. In both groups, the imposition of post-stimulus delays displaced the bisection point (duration yielding 50% choice of lever B) towards longer durations; this effect was significantly greater in the lesioned group than in the control group. Imposition of post-stimulus delays resulted in increases in the Weber fraction, which did not differ significantly between the two groups. The levels of 5HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not altered.

Effect of destruction of the 5-hydroxytryptaminergic pathways on behavioural timing and "switching" in a free-operant psychophysical procedure

This experiment examined the effect of destruction of the ascending 5-hydroxytryptaminergic (5HTergic) pathways on performance in a free-operant timing schedule. Rats received either injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei or sham lesions. They were trained to press levers for a sucrose reinforcer. Training sessions consisted of 40, 50-s trials in which reinforcers were available on a variable-interval 25-s schedule; in the first 25 s of each trial, reinforcers were only available for responses on lever A, whereas in the last 25 s reinforcers were available only for responses on lever B. Data were collected from probe trials (four per session) in which no reinforcers were delivered, during the last ten of 50 training sessions. Both groups showed decreasing response rates on lever A and increasing response rates on lever B as a function of time from the onset of the trial. Response rate on lever B, expressed as a percentage of overall response rate, could be described by a two-parameter logistic function; neither the indifference point (i.e. the time corresponding to 50% responding on lever B) nor the slope of the function different between the two groups. However, the lesioned group showed a higher rate of switching between response alternatives than the sham-lesioned group. The levels of 5HT and 5-hydroxyindoleacetic acid were reduced in the brains of the lesioned rats, but the levels of noradrenaline and dopamine were not significantly altered. The results confirm previous findings that behaviour in timing schedules is sensitive to destruction of the central 5HTergic pathways, and suggest that these pathways may contribute to the inhibitory regulation of switching between behavioural states.

Dopamine withdrawal elicits prolonged calcium rise to support prolactin rebound release

Dopamine (DA) acts directly on pituitary lactotropes to inhibit the release of PRL. Removal of DA elicits a pronounced transient rise in PRL release to values exceeding pre-DA rates (PRL rebound). Electrophysiological studies have shown that lactotropes exhibit a period of increased Ca2+ action potential activity after DA withdrawal, leading to the proposal that enhanced Ca2+ influx during this period may support the rebound secretion of PRL. In the present studies, we investigated the effect of DA application and removal on the cytosolic free calcium concentration ([Ca2+]i) monitored by fura-2 in single rat lactotropes. Unchallenged lactotropes fell into two functionally distinct groups: those with stable [Ca2+]i that was not acutely sensitive to extracellular Ca2+, and those with spontaneous fluctuations in [Ca2+]i that were dependent upon influx of external Ca2+. There was striking variability in the [Ca2+]i patterns of the latter group, ranging from irregular, low amplitude fluctuations to rhythmic, repetitive oscillations with definable rise and decay kinetics. Application of DA resulted in a rapid decrease in [Ca2+]i concomitant with the cessation of these spontaneous [Ca2+]i fluctuations. After DA removal, these cells resumed oscillatory [Ca2+]i activities similar to those observed before DA application. In quiescent lactotropes, acute application of DA exerted no effect on resting [Ca2+]i, but quiescent cells could be activated to produce [Ca2+]i fluctuations by the application and withdrawal of DA. Again, the character of the induced [Ca2+] activity showed significant cell to cell variation. In contrast, the pattern of [Ca2+]i fluctuations was remarkably characteristic in a given cell in response to repeated challenges. A composite [Ca2+]i profile of 13 cells paralleled the PRL secretory rebound after application and removal of DA. The oscillatory rise in [Ca2+]i is functionally linked to the rebound release of PRL after DA removal, as both were immediately abolished by blockade of Ca2+ influx. These data demonstrate that the rebound secretion of PRL is dependent upon enhanced influx of extracellular Ca2+ after cells recover from DA-induced hyperpolarization and support the hypothesis that a population of inactivated Ca2+ channels has been recruited in response to application and withdrawal of DA.

Effects of desipramine and fluvoxamine on timing behavior investigated with the fixed-interval peak procedure and the interval bisection task

Acute treatment with antidepressant drugs is known to increase the mean interresponse time (IRT) in the IRT > 72-s schedule of reinforcement. In order to examine the possibility that this effect may reflect an action of the antidepressants on timing processes, we tested the effects of two antidepressants, desipramine and fluvoxamine, on behaviour maintained under two other timing schedules in rats. In the fixed-interval peak procedure (fixed-interval 30-s), acute treatment with desipramine (8 mg kg-1) reduced response rate, whereas acute treatment with fluvoxamine (8 mg kg-1) increased it. Neither drug significantly altered the time to attainment of peak response rate or the Weber fraction. In the interval bisection task (standard durations 2 s and 8 s), the bisection point was not significantly altered by acute treatment with either drug. Chronic treatment with desipramine (8 mg kg-1 b.d.) had no effect on any of the indices of timing under either schedule. Chronic treatment with fluvoxamine (8 mg kg-1 b.d.) reduced the time to attainment of peak response rate but had no effect on the Weber fraction under the fixed-interval peak procedure, and did not alter the bisection point or Weber fraction under the interval bisection procedure. The failure of desipramine and fluvoxamine to increase the time to peak response rate or the bisection point at doses that significantly altered operant response rate suggests that the effect of these drugs on IRT schedule performance is unlikely to reflect an interaction with timing processes.

Pancreatitis in children--experience with 43 cases

Pancreatitis in children is not common and can be associated with severe morbidity and mortality. We encountered 43 children, ranging in age from 2 to 18 years, with pancreatitis over the past 10 years. The diagnosis of pancreatitis was made in those patients who showed: (1) significant intra-operative pathology or; (2) clinical findings of pancreatic inflammation and laboratory confirmation. More than one third (16 cases) of the cases were due to trauma, other causes included systemic disease (10), structural disease (8), and toxins or drugs (4). Five cases were classified as idiopathic. Most of the patients presented with abdominal pain (95%) and vomiting (56%). Jaundice was found in 7 patients and an abdominal mass in 2. Morbidity included pseudocyst (10), relapse (4), hyperglycaemia (4) and miscellaneous problems. Eight (50%) of the patients with trauma and 6 (86%) of the patients with structural diseases required surgery. Other patients were managed conservatively with bowel rest, gastric decompression, intravenous fluid and total parenteral nutrition. One case had a fatal outcome. All the survivors did well in long term follow up. Relevant literature has been reviewed and the sensitivity of various diagnostic modalities compared and discussed. A lesser known association between pancreatitis and structural anomalies such as choledochal cyst is discussed. To our knowledge, the present review is the first on pancreatitis in Chinese children.

CONCLUSION

Pancreatitis can occur from a wide variety of causes and may result in severe complications. Early diagnosis, close monitoring and aggressive intervention are mandatory to reduce morbidity and mortality.