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Biomedical subjects

D Dawson

Publications and source records attributed to D Dawson.

At least 73 records · Page 4Linked to original sources
PubMed1999

Long-term contracts in the NHS: a solution in search of a problem?

Purchasers and providers in the National Health Service (NHS) are now required to move from annual contracting cycles to longer-term contracts. The benefits are expected to include more efficient investment and improved sharing of financial risk. This paper argues that the economic analysis of longer-term contracts has assumed implicitly that agents operate in the private sector. Once the constraints of the public sector are introduced, the apparent economic benefits of longer-term contracts become doubtful. The paper explores these issues using evidence collected from analysis of the contracts of a sample of Health Authorities and from semi-structured interviews with individuals involved in the contracting process. We conclude that with the property rights and financial structure of the public sector, the move from short- to long-term contracts is unlikely to produce the improvements in performance expected by the government.

Contract Services↗
PubMed1999

Peripheral heat loss: a predictor of the hypothermic response to melatonin administration in young and older women.

Core hypothermia following daytime melatonin administration typically displays significant interindividual variability. As this hypothermia has been associated with significant increases in skin temperature, the mechanism by which melatonin decreases core temperature may involve increasing peripheral heat loss. If so, the interindividual variability in this effect may reflect concomitant interindividual variability in heat loss capacity at the distal periphery. For six younger (mean +/- SEM: 23.4 +/- 0.3 years) and 10 older women (mean +/- SEM: 65.6 +/- 0.7 years), the maximum decrease in core body temperature following a 5-mg (p.o.) dose of melatonin was correlated with the capacity to lose heat. This was determined by the maximum increase in contralateral hand temperature following a mild positive thermal challenge (PTC). The regression analysis yielded a significant (p < 0.01) correlation of 0.80, suggesting that the individual magnitude of hypothermia following melatonin administration may reflect the capacity of an individual to dissipate heat at the distal periphery.

Adult↗
PubMed1999

Quality and accountability: Children's emergency services in a managed care environment.

The fast pace of change in the health care system has sparked growing interest among purchasers, consumers, providers, health plans, and others in evaluating and improving the quality of health services. The Emergency Medical Services for Children Program's Managed Care Task Force recommended the development of a white paper to focus on issues related to quality and accountability in children's emergency medical services in a managed care environment. A literature review was conducted, and a panel reviewed and discussed relevant materials. The panelists then developed recommendations as a resource for managed care organizations, providers of care, professional associations, and federal, state, and local policymakers.

Adolescent↗
PubMed1999

Disseminated Mycobacterium genavense infection in a FIV-positive cat.

An 8-year-old FIV-positive Australian cat was presented with coughing, periocular alopecia, pyrexia and inappetence. Skin scrapings demonstrated Demodex cati mites. Antibiotics were administered and it was treated successfully for periocular demodectic mange, but the cat continued to exhibit respiratory signs and lose weight. Further investigation revealed an ascarid infection and active chronic inflammation of undetected cause affecting the lower airways. Repetitive treatment with pyrantel failed to eradicate the ascarid infection. The cat became cachectic and developed moist ulcerative dermatitis of the neck, severe non-regenerative anaemia, leucopenia and thrombocytopenia. Necropsy and histopathology revealed mycobacteriosis affecting skin, lungs, spleen, lymph nodes, liver and kidney. Attempted culture of frozen tissues at a mycobacteria reference laboratory was unsuccessful. Paraffin-embedded, formalin-fixed tissue was retrieved and examined using PCR to amplify part of the 16S rRNA gene. A diagnosis of disseminated Mycobacterium genavense infection was made based on the presence of acid fast bacteria in many tissues and partial sequence of the 16S rRNA gene. Although M genavense has been identified previously as a cause of disseminated disease in AIDS patients, this is the first report of infection in a cat. It was suspected that the demodecosis, recurrent ascarid infections and disseminated M genavense infection resulted from an immune deficiency syndrome consequent to longstanding FIV infection.

Animals↗
PubMed1999

The relationship between 6-sulphatoxymelatonin and polysomnographic sleep in good sleeping controls and wake maintenance insomniacs, aged 55-80 years.

The pineal hormone, melatonin, is reported to possess hypnotic properties. This has led to an investigation of the relationship between the endogenous melatonin rhythm and sleep. However, this relationship has yet to be fully examined in aged insomniacs and controls. From media advertisements, 16 good sleeping controls (11F, 5M) and 16 sleep maintenance insomniacs (11F, 5M), aged over 55 years, were recruited to participate in a study involving four nights of polysomnographically (PSG) measured sleep followed by a 26 h constant routine. During the constant routine, 2 h urine samples were collected and analysed for the melatonin metabolite, 6-sulphatoxymelatonin (aMT.6S). This was used to determine total melatonin excretion. As well, the following circadian melatonin parameters were calculated from fifth order polynomial curve fitting analyses, the goodness of the polynomial curve fit, peak melatonin concentration, the phase of the melatonin rhythm, and melatonin and sleep rhythm synchrony. Apart for one control, all subjects showed significant circadian melatonin rhythms. Although insomniacs showed a greater amount of wakefulness, less sleep in total, and lower sleep efficiency, no significant group differences were observed in any of the melatonin parameters. In addition, while subjects with more reliable melatonin curve fits showed shorter sleep latencies and higher sleep efficiencies, correlational analyses revealed no other significant relationships between any melatonin and PSG sleep parameters. Overall, the present results suggest that neither melatonin amplitude nor phase are related to sleep quality in the aged.

Aged↗
PubMed1999

Quantifying the performance impairment associated with fatigue.

The present study systematically compared the effects of fatigue and alcohol intoxication on a range of neurobehavioural tasks. By doing so, it was possible to quantify the performance impairment associated with fatigue and express it as a blood alcohol impairment equivalent. Twenty-two healthy subjects aged 19-26 years participated in three counterbalanced conditions. In the sustained wakefulness condition, subjects were kept awake for 28 h. In the alcohol and placebo conditions, subjects consumed either an alcoholic or non-alcoholic beverage at 30 min intervals, until their blood alcohol concentration reached 0.10%. In each session, performance was measured at hourly intervals using four tasks from a standardised computer-based test battery. Analysis indicated that the placebo beverage did not significantly effect mean relative performance. In contrast, as blood alcohol concentration increased performance on all the tasks, except for one, significantly decreased. Similarly, as hours of wakefulness increased performance levels for four of the six parameters significantly decreased. More importantly, equating the performance impairment in the two conditions indicated that, depending on the task measured, approximately 20-25 h of wakefulness produced performance decrements equivalent to those observed at a blood alcohol concentration (BAC) of 0.10%. Overall, these results suggest that moderate levels of fatigue produce performance equivalent to or greater than those observed at levels of alcohol intoxication deemed unacceptable when driving, working and/or operating dangerous equipment.

Adult↗
PubMed1999

Mode switching in dual chamber pacemakers: effect of onset criteria on arrhythmia-related symptoms.

AIMS: Various mode-switching algorithms are available with different tachyarrhythmia detection criteria to be satisfied to initiate mode-switching. This study evaluated three different mode-switching algorithms in patients with paroxysmal atrial fibrillation. METHODS AND RESULTS: Seventeen patients completed the study. Three mode-switching algorithms were downloaded as software into the pacemaker, each for 1 month in a single-blind, randomized sequence. The criteria to initiate mode-switching were: mean atrial rate ('standard'), '4-of-7' or '1-of-1' atrial intervals to exceed the atrial detection rate. Symptoms for each were measured using the Symptom Checklist Frequency and Severity index. The median number of mode-switch episodes increased from 20 for 'standard' to 39 for '4-of-7' (P=0.029 vs 'standard') and 103 for '1-of-1' (P=0.0012 vs 'standard') onset criteria. Median duration of episodes decreased from 2.5 min with 'standard' to 1.4 min with '4-of-7' and 0.4 min with '1-of-1' onset criteria. Frequency of symptoms was lower using '4-of-7' (18.2 +/- 12.0 vs 23 +/- 12.0, P=0.08) or '1-of-1' (20.4 +/- 12.4 vs 23 +/- 12.0, P=0.07) than 'standard' onset criteria. Severity of arrhythmia tended to be less with either '4-of-7' (16 +/- 10.4 vs 19.1 +/- 19.4, P=0.12) or '1-of-1' (17.5 +/- 10.3 vs 19.1 +/- 9.4, P=0.18) than with 'standard' onset criteria. CONCLUSIONS: The more sensitive onset criteria for detection of atrial tachyarrhythmias were associated with lower frequency and severity of symptoms.

Algorithms↗
PubMed1999

New approaches to ambulatory care facilities in the United Kingdom--an investor developer's perspective.

The purpose of this article is to describe the strategic context within which ambulatory care facilities are being developed, to consider a range of models of care facilities available, and, by drawing on the experience of the authors, to comment on some of the investment and development issues arising from two projects in progress--the community hospitals in Richmond, Yorkshire, in rural north England, and Thames Ditton on the borders of outer south London. In the final section, we consider the possible future of ambulatory care development in the light of government policy.

Ambulatory Care Facilities↗
PubMed1999

Urinary 6-sulfatoxymelatonin excretion and aging: new results and a critical review of the literature.

The apparent age-related decline in melatonin production has been thought to continue in a secular manner across the lifespan. While it is clear that melatonin levels in children and adolescents are elevated compared to older individuals, the question of whether there is a sudden or gradual change has not been adequately addressed. In this study, we report the excretion of the melatonin metabolite, 6-sulfatoxymelatonin in 253 subjects aged between 21 and 82 yr. The correlation with age was significant (r = -0.24; P < 0.05). When the data was analysed by ANOVA using 5-yr age spans, there was a significant effect of age, but post hoc analysis indicated that after 25 yr of age there was no significant decline in excretion of the metabolite. Thus, although the oldest subjects excreted 36% less melatonin metabolite than the youngest, the decrease occurred at a very early age. In the second part of the study, we re-evaluated the data from seven previous studies that measured plasma melatonin levels or metabolite excretion across a wide range of ages and 11 studies comparing young versus older subjects. Statistical analysis by ANOVA again suggested that the changes in melatonin occurring with age were essentially complete before 30 yr of age. The youngest subjects produced at the most twice the amount of melatonin as the oldest subjects. Finally, we evaluated the mean plasma melatonin levels in 144 groups of normal subjects reported in 137 separate publications with respect to age. Again, whereas there was a significant correlation with age, ANOVA showed that there was no difference between groups after 35 yr of age, and the oldest groups had levels that were only 43% of the youngest groups. We conclude that melatonin production is lower in older people, but that the change occurs very early in life, around 20-30 yr of age.

Adolescent↗
PubMed1999

Multicenter evaluation of the Abbott LCx Mycobacterium tuberculosis ligase chain reaction assay.

Four Australian hospital laboratories evaluated the performance of the Abbott LCx Mycobacterium tuberculosis assay with 2,347 specimens (2,083 respiratory and 264 nonrespiratory specimens) obtained from 1, 411 patients. A total of 152 specimens (6.5%) were culture positive for Mycobacterium tuberculosis complex (MTBC); of these, 79 (52%) were smear positive. After resolution of discrepant data, the overall sensitivity, specificity, and positive and negative predictive values for the LCx assay were 69.7, 99.9, 99.1, and 97.7% respectively. For smear-positive respiratory specimens that were culture positive for MTBC, the values were 98.5, 100, 100, and 98.4%, respectively, while the values for smear-negative respiratory specimens were 41.5, 99.9, 96.4, and 98%, respectively. Relative operating characteristic curves were constructed to demonstrate the relationship between sensitivity and specificity for a range of possible cutoff values in the LCx assay. These graphs suggested that the assay sensitivity for respiratory samples could be increased from 70.2 to 78.6%, while the specificity would be reduced from 99.9 to 99.4% by inclusion of a grey zone (i.e., LCx assay values of between 0.2 and 0.99). An algorithm is presented for the handling of specimens with LCx assay values within this grey zone.

DNA Ligases↗
PubMed1999

Thermoregulatory and soporific effects of very low dose melatonin injection.

The effect of a rapid increase in circulating melatonin on body temperatures and sleepiness was investigated in eight young adults at 1000. Melatonin administered intravenously at 10- and 30-microgram doses, but not 3 microgram, resulted in elevated plasma and saliva levels consistent with endogenous levels measured in adults at night. Melatonin at 10 and 30 microgram significantly attenuated the daytime increase in rectal core temperature (P < 0.05 for both). The mean maximum rectal core temperature differences between saline and melatonin treatment were 0.11 +/- 0.03 degreesC, 0.16 +/- 0.04 degreesC, and 0.18 +/- 0.04 degreesC after the 3-, 10-, and 30-microgram melatonin doses, respectively. All three doses significantly increased hand temperature compared with saline (P < 0. 05) within 30 min. The mean maximum hand temperature differences were 0.72 +/- 0.12 degreesC (3 microgram), 0.95 +/- 0.15 degreesC (10 microgram), and 0.65 +/- 0.11 degreesC (30 microgram). Foot temperature and subjective sleepiness measures did not change at any melatonin dose. The results suggest that daytime intravenous injection of melatonin to achieve normal nocturnal levels in young adults may produce significant thermoregulatory changes without soporific effects.

Adult↗
PubMed1999

Contracting for quality: does length matter?

OBJECTIVES: To examine whether longer-term contracts for health services will shift attention away from concern for finance and activity levels and towards the achievement of better quality services. METHODS: Analysis of 288 contracts from the British National Health Service (NHS) and 12 semi-structured interviews with staff from provider (NHS hospital trusts) and purchaser (health authorities) organisations. RESULTS: No relationship was found between the duration of a contract and the duration of service specifications or quality frameworks. The annual contracting cycle is concerned largely with ensuring that all parties stay within activity targets and financial constraints, and this is unlikely to be affected by a shift to longer-term contracts. The setting of standards and initiatives to improve quality is largely independent of the contracting process and the duration of contracts, and relies on relationships rather than contracts. CONCLUSIONS: It is optimistic to expect longer-term contracts automatically to produce a greater focus on quality and the incentives needed to ensure that improvements in quality are delivered. However, this may not matter as issues of quality are being addressed more appropriately in the British NHS through a variety of other routes.

Contract Services↗