Unpredictable and uncontrollable stress impairs neuronal plasticity in the rat hippocampus

Almost by definition, learning and the effect of stress on learning represent modifications of existing neuronal circuitry. Under some circumstances, this modification can be measured electrophysiologically. One such measure of plasticity is long-term potentiation (LTP), a long-lasting increase in synaptic efficacy following brief exposure to tetanic stimulation. In 1987, Foy et al. reported that hippocampal LTP was impaired by exposure to inescapable shock. We have recent evidence that the impairment in LTP can be prevented by allowing the animal to learn to escape the shock (Shors et al., 1989), indicating that the stress effect is to some extent mediated by "psychological" variables. Regardless of LTP's putative role in learning and memory processes, such a stress-induced decrease in neuronal plasticity is likely to have profound effects on the behaving organism.     

Patient-focused care: key principles to restructuring

Patient-focused care (PFC) is a unique patient care delivery model that is becoming more popular in today's hospitals. Bishop Clarkson Memorial Hospital in Omaha, Nebraska, was one of the first hospitals to implement PFC. Clarkson used four principles to guide its pilot unit implementation--grouping similar patient populations, moving services closer to the patient, broadening staff skills, and simplifying processes. The four principles and their implementation are described; preliminary results are reported.     

Dyadic reciprocal associations between self-efficacy and planning predict sedentary behaviour

Objectives

There are two alternative hypotheses regarding bidirectional associations between self-efficacy and planning in predicting health behaviour change: self-efficacy may establish planning (cultivation hypothesis) or planning may enable the formation of self-efficacy (enabling hypothesis). This study investigates the order in which these two social cognitions are linked in adult–adult dyads in the context of sedentary behaviours (SB).

Design

A longitudinal study with 4 measurement points, spanning 8 months.

Methods

A total of 320 dyads (age: 18–90 years) were enrolled. Dyads included a focus person (who received the recommendation to reduce SB and intended to change their SB), and their partners, who were willing to support the focus persons and intended to reduce their own SB as well. Data were collected at Time 1 (T1), Time 2 (1 week later, T2), Time 3 (T3, 2 months after T1) and Time 4 (T4, 8 months after T1). SB was measured with accelerometers at (T1 and T4). Mediation models with individual and dyadic reciprocal effects were tested with path analyses.

Results

Only one indirect effect was found: A higher level of partners' SB reduction-specific self-efficacy at T2 was related to the focus person's more frequent planning to reduce SB at T3, which, in turn, predicted lower SB time among partners at T4.

Conclusions

The findings provide partial support for the cultivation model (self-efficacy prompting planning) and for dyadic reciprocal associations in the context of SB time reduction among adult dyads.     

Women in general practice in New Zealand

AIM: To investigate the role of women general practitioners (GPs) in New Zealand. METHOD: A five-page questionnaire was posted to 200 randomly selected women GPs from throughout New Zealand. One follow-up mailing was sent. RESULTS: A response rate of 79% was achieved. Twenty-four percent of women GPs work less than 5/10 but 46% earn less than $40000. Forty-eight percent of women GPs' partners also earn less than $40000. The most common reason for working part-time was parenting responsibilities. Eighty-seven percent are married or live with a partner, 77% have children, 48% have preschool-aged children. Only 15% have Membership of the RNZCGP and 57% are owner or partner in their practice. CONCLUSION: Women GPs suffer both professional and financial difficulties because of their dual motherhood/professional roles.     

Use of Biota-Sediment Accumulation Factors to assess similarity of nonionic organic chemical exposure to benthically-coupled organisms of differing trophic mode

The U.S. Environmental Protection Agency is in the process of developing Sediment Quality Criteria (SQC) to specify the acceptable degree of risk from sediment-mediated chemical exposure for the protection of benthically-coupled organisms. In this study, potential differences in chemical exposure for benthic organisms of differing habitats or feeding types were evaluated through the use of Biota-Sediment Accumulation Factors (BSAFs). It was hypothesized that If species of different habitats have similar exposures, then the BSAF values should not be different. The BSAFs are calculated using the concentrations of chemicals in an organism (g/g lipid) divided by the concentrations of the same chemicals in sediment (g/g_oc). Data from both freshwater and saltwater studies that met specified criteria for data quality were obtained from published papers or reports. These included three laboratory and five field studies containing 27 species and 4054 BSAF values. The BSAFs were intercompared for similarity of central tendency as grouped by chemical class (PCBs, PAHs, pesticides), individual species, and species grouped by habitat (infaunal deposit feeder, scavenger, filter feeder, and benthically-coupled fish). Plots of BSAFs grouped by class and K_ow revealed that the BSAFs for the PAHs were uniformly lower (mean 0.34) than the PCB (1.03) or pesticide (1.36) classes. For the PCBs, the BSAFs for all species exhibited a K_ow dependency with decreased bioaccumulation evident above and below the range of 5.99–7.27 log₁₀ K_ow. In order to optimize the detection of species/habitat differences in the BSAFs, further analyses were segregated by chemical class and excluded PCB data outside the above K_ow range. These analyses revealed similar BSAF values for various species both within and among habitat groups, and indicated that the sum total of exposures from all routes is similar across species. This similarity of chemical exposure across benthic species, and the similarity of sensitivities between benthic species and species used to derive WQC FCVs supports the applicability of SQC for all benthic organisms as a group.Contribution No. 1641 of the U.S. Environmental Protection Agency, Environmental Research Laboratory, Narragansett, RI     

Early discharge for patients with exacerbations of chronic obstructive pulmonary disease: a randomized controlled trial

BACKGROUND: We have previously reported the use of a hospital based respiratory nurse service (Acute Respiratory Assessment Service, ARAS) to support home treatment of patients with exacerbations of chronic obstructive pulmonary disease (COPD). A controlled trial was undertaken to compare early discharge with home treatment supported by respiratory nurses with conventional hospital management of patients admitted with exacerbations of COPD. METHODS: Patients with COPD admitted as emergencies were identified the next working day. They were eligible for inclusion in the study if the differential diagnosis included an exacerbation of COPD, but were excluded if other medical conditions or acidotic respiratory failure required inpatient investigation or management. Of 360 patients reviewed, 209 were being assessed for other active medical problems and were excluded, 33 potential participants were already involved in research studies and so were ineligible, and 37 did not wish to participate in the study. Eighty one patients were randomised to receive conventional inpatient care (n=40) or to planned early discharge the next working day (n=41). Those discharged early continued treatment at home under the supervision of specialist respiratory nurses. Outcome measures were readmission, additional hospital days, and deaths within 60 days of initial admission. Process measures included number of visits, duration of follow up by the respiratory nurse, and additional treatment provided to support early discharge. RESULTS: On an intention to treat basis, a policy of early discharge reduced inpatient stay from a mean of 6.1 (range 1-13) days with conventional management to 3.2 (1-16) days with an early discharge policy. Twelve patients (30% conventional management, 29.3% early discharge) were readmitted in each group giving a mean difference in readmission of 0.7% (95% CI of the difference -19.2 to 20.6). In the conventional management group readmitted patients spent a mean of 8.75 additional days in hospital compared with 7.83 days in the early discharge group, giving a mean difference of 0.92 days (95% CI of the difference -6.5 to 8.3). There were two deaths (5%) in the conventional management group and one (2.4%) in the early discharge group, a mean difference of 2.6% (95% CI of the difference -5.7 to 10.8). CONCLUSIONS: Patients with acute exacerbations of COPD uncomplicated by acidotic respiratory failure or other medical problems can be discharged home earlier than is current practice with support by visiting respiratory nurses. No difference was found in the subsequent need for readmission.     

Using fMRI to quantify the time dependence of remifentanil analgesia in the human brain.

To understand and exploit centrally acting drugs requires reliable measures of their time course of action in the human brain. Functional magnetic resonance imaging (fMRI) is able to measure noninvasively, drug-induced changes in task-related brain activity. Here, we have characterized, in a specific region of the brain, the time of onset of action and the half-life of action of a clinically relevant dose of a potent opioid analgesic agent, remifentanil. These times were established from the temporal variation of the amplitude of the blood oxygen level-dependent response in the insular cortex contralateral to a painfully hot thermal stimulus, in volunteers receiving a remifentanil infusion. The insular cortex has repeatedly been reported as activated by noxious thermal stimulation. The times of onset and offset of drug action were each characterized by a half-life for changes in fMRI signal from within the insula. These characteristic times agreed with the observed drug-induced analgesia and previous pharmacokinetic-pharmacodynamic measurements for remifentanil. We have successfully measured, for the first time using fMRI, temporal pharmacological parameters for a CNS-active drug based on its effect on task-related activity in a specific brain region. Comparison of the time course of regional brain activity with pain perception could reveal those regions engaged in drug-induced analgesia.