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Biomedical subjects

Peter Raven

Publications and source records attributed to Peter Raven.

7 recordsLinked to original sources
PubMed2007

Teaching undergraduate psychiatry in primary care: the impact on student learning and attitudes.

OBJECTIVE: To explore the impact of undergraduate psychiatry placements in primary care settings on students' learning and attitudes to mental illness. DESIGN: Questionnaire survey and qualitative in-depth interviews. SETTING: A primary care-based psychiatry undergraduate teaching programme at Royal Free and University College Medical School, London. PARTICIPANTS: A total of 145/183 (79.2%) students attending the primary care-based programme over 2 academic years completed a questionnaire survey. In-depth interviews were conducted with 14 students, 12 general practitioner (GP) tutors and 20 patients participating in the course. RESULTS: In the questionnaire survey, 121/144 (84.0%) students valued the primary care-based teaching highly. In total, 87/139 (62.6%) students felt their attitudes to mental illness had changed as a result of the course. In-depth interviews demonstrated 4 key benefits of the teaching programme: increasing breadth of experience, understanding the patients' experience, learning about mental illness from a GP's perspective and changing students' attitudes towards mental illness. The students' attitudinal shift comprised 2 main dimensions; 'normalisation' of mental illness and increased empathy. CONCLUSIONS: Learning psychiatry in primary care settings offers students a broader experience of a range of patients than in hospital settings and encourages a 'person-centred' approach, which in turn can have a positive impact on their attitudes to mental illness, reducing stereotyping and increasing empathy.

Adult↗
PubMed2006

The incidence of delirium associated with orthopedic surgery: a meta-analytic review.

BACKGROUND: The aim of this study was to perform a systematic review and meta-analysis of the literature regarding the incidence of delirium following orthopedic surgery. METHODS: Relevant papers were sourced from online databases and gray literature. Included studies used a validated diagnostic method to measure the incidence of delirium in a prospective sample of adult/elderly orthopedic patients. Data were subject to meta-analysis after stratification by type of surgery (elective v. emergency) and inclusion/exclusion of pre-existing cognitive impairment. A funnel plot assessed for publication bias. RESULTS: 26 publications reported an incidence of postoperative delirium of 4-53.3% in hip fracture samples and 3.6-28.3% in elective samples. Significant heterogeneity was evident, and this persisted despite stratification. Hip fracture was associated with a higher risk of delirium than elective surgery both when the cognitively impaired were included in the sample (random effects pooled estimate = 21.7% [95% CI = 14.6-28.8] vs. 12.1% [95% CI = 9.6-14.6]), and when the cognitively impaired were excluded (random effects pooled estimate = 25% [95% CI = 15.7-34.7] vs. 8.8% [95% CI = 4.1-13.6]). The funnel plot showed a deficit of small studies showing low risk and large studies showing high risk. In eight hip fracture studies, the proportion of delirium cases with a preoperative onset ranged from 34 to 92%. CONCLUSIONS: Delirium occurs more commonly with hip fracture than elective surgery, and frequently has a preoperative onset when associated with trauma. Recommendations are made with the aim of standardizing future research in order to further explore and reduce the heterogeneity and possible publication bias observed.

Aged↗
PubMed2006

Human impacts on the rates of recent, present, and future bird extinctions.

Unqualified, the statement that approximately 1.3% of the approximately 10,000 presently known bird species have become extinct since A.D. 1500 yields an estimate of approximately 26 extinctions per million species per year (or 26 E/MSY). This is higher than the benchmark rate of approximately 1 E/MSY before human impacts, but is a serious underestimate. First, Polynesian expansion across the Pacific also exterminated many species well before European explorations. Second, three factors increase the rate: (i) The number of known extinctions before 1800 is increasing as taxonomists describe new species from skeletal remains. (ii) One should calculate extinction rates over the years since taxonomists described the species. Most bird species were described only after 1850. (iii) Some species are probably extinct; there is reluctance to declare them so prematurely. Thus corrected, recent extinction rates are approximately 100 E/MSY. In the last decades, the rate is <50 E/MSY, but would be 150 E/MSY were it not for conservation efforts. Increasing numbers of extinctions are on continents, whereas previously most were on islands. We predict a 21st century rate of approximately 1,000 E/MSY. Extinction threatens 12% of bird species; another 12% have small geographical ranges and live where human actions rapidly destroy their habitats. If present forest losses continue, extinction rates will reach 1,500 E/MSY by the century's end. Invasive species, expanding human technologies, and global change will harm additional species. Birds are poor models for predicting extinction rates for other taxa. Human actions threaten higher fractions of other well known taxa than they do birds. Moreover, people take special efforts to protect birds.

Animals↗
PubMed2005

The influence of hostility and family history of cardiovascular disease on autonomic activation in response to controllable versus noncontrollable stress, anger imagery induction, and relaxation imagery.

Autonomic activation in response to controllable versus noncontrollable stress, anger imagery induction, and relaxation imagery was studied among 80 participants between the ages of 18 and 34 years. Participants differed in level of trait hostility and family history of cardiovascular disease. Results were obtained through power spectral analyses of electrocardiograph R-R intervals, which produced an index of autonomic nervous system activation. For both male and female populations, parasympathetic regulation was diminished during anger induction for individuals with high levels of trait hostility and having a family history of cardiovascular disease. Similar results were obtained for women during the uncontrolled stress condition. Based on family history of cardiovascular disease and trait hostility, men responded differentially to relaxation imagery induction, whereas no differences were found among females.

Adult↗
PubMed2003

Inhibition of alpha-adrenergic vasoconstriction in exercising human thigh muscles.

The mechanisms underlying metabolic inhibition of sympathetic responses within exercising skeletal muscle remain incompletely understood. The aim of the present study was to test whether alpha(2)-adrenoreceptor-mediated vasoconstriction was more sensitive to metabolic inhibition than alpha(1)-vasoconstriction during dynamic knee-extensor exercise. We studied healthy volunteers using two protocols: (1) wide dose ranges of the alpha-adrenoreceptor agonists phenylephrine (PE, alpha(1) selective) and BHT-933 (BHT, alpha(2) selective) were administered intra-arterially at rest and during 27 W knee-extensor exercise (n= 13); (2) flow-adjusted doses of PE (0.3 microg kg(-1) l(-1)) and BHT (15 microg kg(-1) l(-1)) were administered at rest and during ramped exercise (7 W to 37 W; n= 10). Ultrasound Doppler and thermodilution techniques provided direct measurements of femoral blood flow (FBF). PE (0.8 microg kg(-1)) and BHT (40 microg kg(-1)) produced comparable maximal reductions in FBF at rest (-58 +/- 6 versus-64 +/- 4%). Despite increasing the doses, PE (1.6 microg kg(-1) min(-1)) and BHT (80 microg kg(-1) min(-1)) caused significantly smaller changes in FBF during 27 W exercise (-13 +/- 4 versus-3 +/- 5%). During ramped exercise, significant vasoconstriction at lower intensities (7 and 17 W) was seen following PE (-16 +/- 5 and -16 +/- 4%), but not BHT (-2 +/- 4 and -4 +/- 5%). At the highest intensity (37 W), FBF was not significantly changed by either drug. Collectively, these data demonstrate metabolic inhibition of alpha-adrenergic vasoconstriction in large postural muscles of healthy humans. Both alpha(1)- and alpha(2)-adrenoreceptor agonists produce comparable vasoconstriction in the resting leg, and dynamic thigh exercise attenuates alpha(1)- and alpha(2)-mediated vasoconstriction similarly. However, alpha(2)-mediated vasoconstriction appears more sensitive to metabolic inhibition, because alpha(2) is completely inhibited even at low workloads, whereas alpha(1) becomes progressively inhibited with increasing workloads.

Adrenergic alpha-1 Receptor Agonists↗
PubMed2002

Double blind randomised placebo controlled trial of low dose melatonin for sleep disorders in dementia.

BACKGROUND: Disturbance of sleep is common in individuals with dementia where there may be reversal of the sleep-wake cycle. People with dementia of the Alzheimer's type have melatonin secretion rhythm disorders. There is some evidence that treatment with exogenous melatonin is an effective treatment for sleep disturbance associated with dementia. A randomised double blind placebo controlled cross over trial was undertaken to test the hypothesis that slow release exogenous melatonin 6 mg improves sleep for people with dementia. METHODS: Forty-four participants with DSM-IV diagnoses of dementia with sleep disturbance were selected for a seven week randomised double blind cross over trial of slow release melatonin 6 mg versus placebo. Sleep parameters were objectively measured using wrist actigraphy. RESULTS: Twenty-five out of 44 completed the trial. Sleep was significantly disturbed in the sample population. Melatonin had no effect on median total time asleep (n=25, z=1.35, p=0.18), number of awakenings (n=25, z=0.32, p=0.75) or sleep efficiency (n=25, z=0.17, p=0.24). Nor were there any carry over effects from melatonin. CONCLUSIONS: Contrary to previous findings, we found no evidence that two weeks of exogenous melatonin is effective in improving sleep in people with dementia, although possible benefits of melatonin following longer periods of administration cannot be discounted.

Aged↗