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Biomedical subjects

Michael Harrison

Publications and source records attributed to Michael Harrison.

12 recordsLinked to original sources
PubMed2006

Influence of a health education intervention on physical activity and screen time in primary school children: 'Switch Off--Get Active'.

Low levels of physical activity coupled with high levels of television viewing have been linked with obesity in children. The objective of this study was to assess the efficacy of 'Switch Off-Get Active', a 16-week controlled health education intervention, in increasing physical activity and reducing screen time and BMI in primary school children. A secondary objective was to compare children with high and low screen time. Participants were 312 children aged 10.2+/-0.7 years, attending nine schools in areas of social disadvantage. The 10-lesson, teacher-led intervention, conducted in spring 2003, emphasised self-monitoring, budgeting of time and selective viewing. Differences, adjusted for baseline values by ANCOVA, existed between intervention and control children at follow-up for self-reported physical activity (intervention +0.84 30 min blocks/day, 95%CI 0.11-1.57, p<0.05) and self-efficacy for physical activity (p<0.05) but not self-reported screen time (intervention--0.41 blocks/day, 95%CI--0.93-0.12, p=0.13) or BMI (p=0.63). Cross-sectional comparisons at baseline indicated lower physical activity, self-efficacy for physical activity and aerobic fitness and a higher BMI in children with high screen time. In conclusion, health education interventions can increase physical activity in primary school children but follow-ups of longer duration may be needed to demonstrate intervention effects on BMI.

Case-Control Studies↗
PubMed2006

Cognitive functioning pre- to post-kidney transplantation--a prospective study.

BACKGROUND: Kidney transplantation (TX) may ameliorate the neuropsychological (NP) impairments in end-stage renal disease (ESRD). Previous studies have suffered from small sample sizes, lack of standardization of dialysis adequacy, and insufficiently sensitive NP tests. METHODS: Twenty-eight medically stable patients aged 44.04 (12.01) years with ESRD were investigated before and at 6 months after successful kidney TX using an NP test battery, which assessed attention-concentration, psychomotor ability and memory. Formal kinetic modelling of dialysis delivery ensured adequate renal replacement therapy. Transplant function was good on stable doses of immunosuppressive medication, without evidence of rejection at the time of testing. RESULTS: Within-subject comparisons showed statistically significant improvement in memory performance after kidney TX. Other NP measures (attention-concentration and psychomotor abilities) showed non-significant improvements. Normative comparisons showed NP impairments on dialysis, which were not apparent after TX. CONCLUSION: These data demonstrate improvements in cognition following kidney TX and emphasize the reversibility of the memory problems evidenced in dialysis.

Adult↗
PubMed2006

Relationship between white cell count, neuropsychologic outcome, and microemboli in 161 patients undergoing coronary artery bypass surgery.

OBJECTIVE: Neuropsychologic impairment remains a problem after coronary artery bypass grafting. Relatively few studies have examined the potential role of the perioperative inflammatory response. This study aimed to determine whether there was any association between perioperative white cell count, microemboli, and cognitive performance after surgical intervention. METHODS: White cell count and differential were prospectively measured perioperatively in 161 patients undergoing coronary artery bypass grafting. A neuropsychologic test battery (9 tests) was administered preoperatively and 6 to 8 weeks postoperatively in all 161 patients. Cerebral microemboli during cardiopulmonary bypass were also recorded by means of a transcranial Doppler scan of the right middle cerebral artery. RESULTS: There was no correlation between microemboli and white cell counts at any time point. There were weak but significant inverse correlations between both preoperative (r = -0.19, P = .02) and postoperative (r = -0.21, P < .01) white cell count and a measure of overall neuropsychologic test performance (total z change score). There was a weak but significant positive correlation between the neutrophil count 10 minutes after bypass and the intraoperative microemboli count (r = 0.23, P = .01). CONCLUSIONS: The correlation between white cell count and neuropsychologic outcome suggests that an inflammatory response might have a role in determining cognitive outcome after coronary artery surgery with cardiopulmonary bypass. The positive correlation between the microemboli during cardiopulmonary bypass and the neutrophil count 10 minutes after bypass is compatible with microemboli contributing to the inflammatory response. The patients' preoperative inflammatory status might also be predictive of the response to surgical intervention.

Cognition Disorders↗
PubMed2006

Redesigning health systems for quality: Lessons from emerging practices.

BACKGROUND: It has been five years since the Institute of Medicine (IOM) report, Crossing the Quality Chasm, proposed systemwide changes to transform our health care system. What progress has been made? What lessons have been learned? How should we move forward? METHODS: Semistructured telephone interviews were conducted with 16 health care providers and researchers at organizations involved in system redesign. The findings were supplemented with a focused literature review and discussions from a national expert meeting. RESULTS: Many promising and innovative examples of redesign were identified. However, even delivery systems that are redesigning care in pursuit of the six IOM aims face daunting challenges, reflecting the need to align system changes across multiple levels and to integrate redesign efforts with ongoing system features. Four success factors were reported by providers as crucial in overcoming redesign barriers: (1) directly involving top and middle-level leaders, (2) strategically aligning and integrating improvement efforts with organizational priorities, (3) systematically establishing infrastructure, process, and performance appraisal systems for continuous improvement, and (4) actively developing champions, teams, and staff. A framework that integrates these success factors to facilitate a systems approach to redesigning health care organizations and delivery systems for improved performance is provided. CONCLUSIONS: Successful system redesign requires coordinating and managing a complex set of changes across multiple levels rather than isolated projects.

Attitude of Health Personnel↗
PubMed2006

Natural history of brain lesions in extremely preterm infants studied with serial magnetic resonance imaging from birth and neurodevelopmental assessment.

OBJECTIVES: The aim was to survey the range of cerebral injury and abnormalities of cerebral development in infants born between 23 and 30 weeks' gestation using serial MRI scans of the brain from birth, and to correlate those findings with neurodevelopmental outcome after 18 months corrected age. METHODS: Between January 1997 and November 2000, consecutive infants born at < 30 weeks' gestational age underwent serial MRI brain scans from birth until term-equivalent age. Infants were monitored after 18 months of age, corrected for prematurity, with the Griffiths Mental Development Scales and neurologic assessment. RESULTS: A total of 327 MRI scans were obtained from 119 surviving infants born at 23 to 30 weeks of gestation. Four infants had major destructive brain lesions, and tissue loss was seen at term for the 2 survivors. Fifty-one infants had early hemorrhage; 50% of infants with term scans after intraventricular hemorrhage had ventricular dilation. Twenty-six infants had punctate white matter lesions on early scans; these persisted for 33% of infants assessed at term. Early scans showed cerebellar hemorrhagic lesions for 8 infants and basal ganglia abnormalities for 17. At term, 53% of infants without previous hemorrhage had ventricular dilation and 80% of infants had diffuse excessive high signal intensity within the white matter on T2-weighted scans. Complete follow-up data were available for 66% of infants. Adverse outcomes were associated with major destructive lesions, diffuse excessive high signal intensity within the white matter, cerebellar hemorrhage, and ventricular dilation after intraventricular hemorrhage but not with punctate white matter lesions, hemorrhage, or ventricular dilation without intraventricular hemorrhage. CONCLUSIONS: Diffuse white matter abnormalities and post-hemorrhagic ventricular dilation are common at term and seem to correlate with reduced developmental quotients. Early lesions, except for cerebellar hemorrhage and major destructive lesions, do not show clear relationships with outcomes.

Basal Ganglia↗
PubMed2004

Neuropsychological performance after kidney transplantation: a comparison between transplant types and in relation to dialysis and normative data.

BACKGROUND: Neuropsychological (NP) performance after kidney transplantation (TX) has received little attention. This study compared NP functioning between dialysis and transplant patients and between living-related donor (LRD) and cadaver (CAD) transplant recipients. The association between immunosuppressive medication and NP outcomes was also examined. METHODS: One hundred and seventeen transplant recipients (25 LRD and 92 CAD patients) and 145 dialysis patients (77 haemodialysis and 68 peritoneal dialysis) were administered an NP test battery to assess learning and verbal recall, attention and concentration, and psychomotor abilities/speed. Biochemical markers of renal function were also assessed. RESULTS: Overall, transplant patients showed normal cognitive functioning in all domains assessed. NP performance was found to be equivalent in both transplant groups and in patients on cyclosporin and those on tacrolimus. ANCOVAs showed that TX patients performed significantly better than dialysis patients on selective NP tests, i.e. the two memory tasks and two out of the four tests of attention. No differences were found in motor tasks. CONCLUSIONS: Our results reveal no evidence of NP deficits in TX patients. The NP advantage of TX relative to dialysis is evident mainly in verbal memory.

Adult↗
PubMed2004

Matrix metalloproteinase genes in Xenopus development.

Matrix metalloproteinases (MMPs) are a large family of proteins in vertebrates, consisting of over 24 genes in humans, only a few of which have been identified in Xenopus. Three genes coding for MMPs in Xenopus have been identified and their expression studied during development. The membrane-bound XMMP-14 and -15 (XMT1-MMP and XMT2-MMP) both showed restricted expression patterns, the former principally localising to cranial neural crest tissues and the latter to the epidermis of the embryo. XMMP-7 codes for an MMP that lacks the hemopexin-like domain. It is expressed exclusively in macrophages or other myeloid cell types from early in development.

Amino Acid Sequence↗
PubMed2004

Macular pigment and percentage of body fat.

PURPOSE: To investigate the relationship between percentage of body fat and macular pigment (MP) optical density. METHODS: One hundred healthy subjects of ages between 22 and 60 years volunteered to participate in this study. MP optical density was measured psychophysically, serum lutein and zeaxanthin were quantified by HPLC, and dietary intake of lutein and zeaxanthin was assessed using a validated food frequency questionnaire. Body fat was measured by dual energy x-ray absorptiometry (DEXA); body mass index (BMI) was also calculated for each subject. Clinical and personal details were recorded, with particular attention directed toward putative risk factors for AMD. RESULTS: There was a significant inverse relationship between the percentage of body fat and MP optical density in males (r=-0.392, P <0.01), and after correcting for age and dietary lutein and zeaxanthin, this inverse relationship remained significant (r=-0.290, P <0.05). The relationship between MP optical density and percentage of body fat in females was inverse, but not significant (r=-0.197, P=0.149). A significant and inverse relationship between serum zeaxanthin and percentage of body fat was observed for females only (r=-0.354, P <0.01). Dietary intake of fat was inversely related to serum lutein and zeaxanthin, and significantly so for lutein (r=-0.256, P <0.05). However, dietary fat was unrelated to MP optical density (r=0.041, P=0.688). CONCLUSIONS: A relative lack of MP is associated with adiposity in men, and may underlie the association between body fat and risk for AMD progression in males. Further, the processes governing accumulation and/or stabilization of lutein and zeaxanthin in fat tissue appear to differ for males and females.

Absorptiometry, Photon↗
PubMed2003

Structure and function of the vacuolar H+-ATPase: moving from low-resolution models to high-resolution structures.

In the absence of a high-resolution structure for the vacuolar H+-ATPase, a number of approaches can yield valuable information about structure/function relationships in the enzyme. Electron microscopy can provide not only a representation of the overall architecture of the complex, but also a low-resolution map onto which structures solved for individually expressed subunits can be fitted. Here we review the possibilities for electron microscopy of the Saccharomyces V-ATPase and examine the suitability of V-ATPase subunits for expression in high yield prokaryotic systems, a key step towards high-resolution structural studies. We also review the role of experimentally-derived structural models in understanding structure/function relationships in the V-ATPase, with particular reference to the complex of proton-translocating 16 kDa proteolipids in the membrane domain of the V-ATPase. This model in turn makes testable predictions about the sites of binding of bafilomycins and the functional interactions between the proteolipid and the single-copy membrane subunit Vph1p, with implications for the constitution of the proton translocation pathway.

Cell Membrane↗
PubMed2002

Quality of life and emotional responses in cadaver and living related renal transplant recipients.

BACKGROUND: The specific impact of transplantation on living related donor (LRD) and cadaver (CAD) kidney transplant recipients and their health-related quality of life (HQoL) has received little attention. This study examined the role of sociodemographic, medical and psychological factors in these two groups. METHODS: A total of 347 transplant recipients (76 LRD and 271 CAD patients) completed the Short Form 36 Health Survey and Transplant Effects Questionnaire. RESULTS: Overall, transplant patients showed satisfactory HQoL particularly with respect to emotional well being. HQoL levels were found to be equivalent in both transplant groups. ANCOVAs showed that LRD recipients expressed more guilt in relation to the donor (P<0.001). Multivariate analysis revealed that worry about the viability and functioning of the transplant alone predicted 15.1% of the variance in the SF-36 mental composite score (MCS) whereas age, income, comorbidities and time on dialysis explained 37.8% of the variance in the SF-36 physical composite score (PCS). Multiple regression analyses performed separately for LRD and CAD patients showed that predictors of MCS and PCS between the two groups were similar. CONCLUSIONS: Our results indicate that different forms of transplantation (LRD vs CAD) may lead to different emotional responses albeit with no apparent quality of life differences. In particular, feelings of guilt appear to be prominent in LRD transplantation.

Adult↗