Reporting attrition in randomised controlled trials.
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Bias↗
Biomedical subjects
Jo C Dumville
Publications and source records attributed to Jo C Dumville.
A systematic review of the effects of calcium supplementation on body weight.
Animal studies and epidemiological studies have suggested that Ca supplementation (with Ca supplements or dairy products) may be associated with weight loss in human adults. We aimed to assess whether any association was present by reviewing relevant randomized controlled trials in human subjects. The study was a systematic review and subsequent meta-analysis of randomized controlled trials that used Ca supplementation as an intervention in persons 18 or more years of age, and that reported body weight as a final outcome. A total of thirteen randomized controlled trials were included in the meta-analysis. There was no association between the increased consumption of either Ca supplements or dairy products and weight loss after adjusting for differences in baseline weights between the control and intervention groups (P=0.19 and 0.85, respectively). We therefore concluded that Ca supplementation has no statistically significant association with a reduction in body weight.
Adult↗
Ethics review in research: research governance also delays research.
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Africa↗
The health-related quality of life of people with peripheral arterial disease in the community: the Edinburgh Artery Study.
BACKGROUND: Previous studies investigating the health-related quality of life of those with peripheral arterial disease have focused on patients recruited from hospital clinics. The health-related quality of life of people with peripheral arterial disease in the general population is unknown. AIMS: We aimed to determine the health-related quality of life of people with intermittent claudication and asymptomatic peripheral arterial disease in the general population and to compare it with those with angina and those with no peripheral arterial disease or angina. DESIGN OF STUDY: Analysis of cross-sectional data from the 12-year follow-up of a population-based cohort. SETTING: Edinburgh, Scotland. METHOD: Data from the Edinburgh Artery Study cohort's 12-year follow-up was analysed. Participants' peripheral arterial disease status was measured using the World Health Organisation intermittent claudication questionnaire and the ankle brachial pressure index. Self-assessed health-related quality of life data was collected using the SF-36 generic questionnaire. Health-related quality of life scores were calculated and their associations with peripheral arterial disease status groups were tested. RESULTS: Subjects with intermittent claudication had significantly worse median health-related quality of life scores than patients without claudication in all domains except social functioning and mental health. Patients with claudication had a significantly lower physical component summary score than those without claudication (P </= 0.001). This association remained after adjustment for age, sex, social class, body mass index, smoking, and angina. Those with angina and claudication had significantly worse physical component summary scores than those with no peripheral arterial disease or angina (P </= 0.001). No significant difference was found in health-related quality of life scores between those with asymptomatic peripheral arterial disease and those with no peripheral arterial disease even after multiple adjustment for confounding factors. CONCLUSION: People with intermittent claudication in the community had impaired health-related quality of life related to reduced physical health, but asymptomatic peripheral arterial disease did not significantly affect health-related quality of life.
Aged↗
Solubilisation of tomato fruit pectins by ascorbate: a possible non-enzymic mechanism of fruit softening.
The aim of this work was to test the hypothesis that endogenous ascorbate, released into the apoplast by membrane permeabilisation early in fruit ripening, could promote the solubilisation and depolymerisation of polysaccharides, and thus contribute to fruit softening. In vitro, ascorbate (1 mM), especially in the presence of traces of either Cu2+ or H2O2, solubilised up to 40% of the total pectin from the alcohol-insoluble residue of mature-green tomato (Lycopersicon esculentum Mill.) fruit. Solubilisation was due to the action of ascorbate-generated hydroxyl radicals (*OH), which can cause non-enzymic scission of polysaccharides. The pectins solubilised by ascorbate in vitro were polydisperse (4-1,000 kDa), partially esterified and galactose-rich. Excised pieces of living tomato fruit released ascorbate into the medium (apoplast); the ability of different tissues to do this increased in the order pericarp < placenta < locule. In all three tissues, but especially in the locule, the ability to release ascorbate increased during ripening. The Cu content of each tissue also increased during ripening, whereas neither Fe nor Mn showed a similar trend. We suggest that progressively increasing levels of Cu and ascorbate in the fruit apoplast would lead to elevated *OH production there and thus to non-enzymic scission of pectins during ripening. Such scission could contribute to the natural softening of the fruit. De-esterified citrus pectin was more susceptible to ascorbate-induced scission in vitro than methylesterified pectin, suggesting a possible new significance for pectin methylesterase activity in fruit ripening. In conclusion, non-enzymic mechanisms of fruit softening should be considered alongside the probable roles of hydrolases, xyloglucan endotransglucosylases and expansins.
Ascorbic Acid↗
Gentiobiose: a novel oligosaccharin in ripening tomato fruit.
Two neutral disaccharides, gentiobiose [beta- D-Glc p-(1-->6)- D-Glc] and nigerose [alpha- D-Glc p-(1-->3)- D-Glc], were detected in tomato ( Lycopersicon esculentum Mill.) pericarp and locule. Gentiobiose was present in the locule of green fruit and ripe fruit at 0.88 and 5.8 micro mol (kg fresh weight)(-1), respectively. When vacuum-infiltrated into green tomato fruit, exogenous gentiobiose (50 or 200 micro g per fruit) hastened the initiation of ripening (as judged by colour change) by 1-3 days relative to fruit that were infiltrated with glucose or isomaltose. Nigerose plus gentiobiose was particularly effective, but nigerose alone had no significant effect. The endogenous disaccharides were found to be present in the apoplastic fluid of the fruit, compatible with a proposed intercellular signalling role. The origin and metabolic fate of the disaccharides were investigated. Phenolic esters of these disaccharides were not detectable in tomato fruit and it is therefore unlikely that the free disaccharides were formed from a pool of such esters. An alternative possible biosynthetic origin, via transglycosylation, is discussed. When [(14)C]gentiobiose was vacuum-infiltrated into unripe or ripe fruit, the disaccharide remained intact for at least 1 h but was largely degraded within 24 h. The results suggest that gentiobiose is a new, naturally occurring oligosaccharin with a rapid turnover rate.
Carbon Radioisotopes↗