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Biomedical subjects

M Ashwell

Publications and source records attributed to M Ashwell.

At least 19 recordsLinked to original sources
PubMed2006

A study of central fatness using waist-to-height ratios in UK children and adolescents over two decades supports the simple message--'keep your waist circumference to less than half your height'.

OBJECTIVE: To examine the influence of age and gender on the waist:height ratio (WHTR) in children and to compare changes over time in WHTR, a measure of central fatness in British children. DESIGN: Representative cross-sectional surveys in 1977, 1987 and 1997. SETTING: Great Britain and Northern Ireland. PARTICIPANTS: Survey 1: children aged 5-16 years measured in 1977 (boys) and 1987 (girls) (BSI, n=8135) and Survey 2: children aged 11-16 measured in 1997 (NDNS, n=773). OUTCOME MEASURES: From Survey 1, waist: height ratio related to age and sex and the proportion of children with a WHTR greater than 0.500 (a boundary value suggested for adults). From Survey 2, comparison of WHTR in children with that from Survey 1 and the actual proportion of children with a WHTR greater than 0.500 compared with the expected proportion using the survey 1 as reference. RESULTS: WHTR decreased with age (P<0.01 for trend), with the mean WHTR being significantly lower in girls (P<0.01). WHTR was significantly greater in children in Survey 2 compared with those measured 10 and 20 years earlier in Survey 1 (P<0.0001). The proportion of children where WHTR exceeded the 0.500 boundary value in Survey 2 was 17% of boys and 11.7% of girls (against 5.0 and 1.5%, respectively, in Survey 1, P<0.0001). The increase in WHTR in boys exceeded that in girls. CONCLUSIONS: Values of WHTR during the past 10-20 years have increased greatly showing that central fatness in children has risen dramatically. WHTR is more closely linked to childhood morbidity than body mass index (BMI) and we suggest it should be used as an additional or alternative measure to BMI in children as well as adults. A simple public health message that is the same for adults and children of both sexes and all ages could be stated as 'keep your waist circumference to less than half your height'.

Adipose Tissue↗
PubMed1997

Association of anthropometric indices with elevated blood pressure in British adults.

OBJECTIVE: To investigate which of six anthropometric indices was most strongly associated with elevated blood pressure and frank hypertension in a representative population sample of young and middle-aged British adults. SUBJECTS: A representative random sample of British adults (2712 men and 3279 women) aged between 18 and 64y, who were resident in England, Scotland and Wales, were studied in the 1984-85 Health and Lifestyle Survey. MEASUREMENTS: Following an interview where demographic, health and lifestyle details were recorded, measurements of height, weight and waist and hip circumference were made by a nurse at a home visit, where blood pressure and medication to control blood pressure were also recorded. BMI and the ratios of waist circumference to height (WHTR) and waist circumference to hip (WHR) were calculated. Respondents with a blood pressure above 140 mm Hg (systolic) and/or 90 mm Hg (diastolic) or who were being treated for hypertension were classified as having elevated blood pressure. RESULTS: For men and women aged 18-39 and 40-64 y the prevalence of elevated blood pressure increased across the quintiles of BMI, weight, waist, WHTR and WHR was P < 0.001 for each, with waist and WHTR having the highest odds ratios. Waist and height adjusted for each other were independently related to the prevalence of elevated blood pressure in 40-64 y old men and women. Height, on its own, was inversely related (P < 0.05) only in the 40-64 y old men. The age adjusted partial correlations between systolic and diastolic blood pressure measurements and the measurements of BMI, weight, waist, WHTR and WHR were close and significant, P < 0.001 for each. The ranking and significance of the correlations were hardly affected by excluding the treated hypertensives. CONCLUSIONS: The prevalence of elevated blood pressure was associated with quintiles of BMI, waist, WHTR, WHR and weight, with WHTR and WHR having the highest odds ratios. Waist and height were independently related to the prevalence of elevated blood pressure.

Adolescent↗
PubMed1994

Obesity in men and women.

The prevalence of obesity in the UK, defined as a Body Mass Index (BMI) exceeding 30, is increasing. Obese people with BMI greater than 30 have a much greater risk of dying earlier than people with desirable levels of fatness (as do extremely lean people with BMI less than 20). The relationship between obesity and the likelihood of suffering certain metabolic diseases such as coronary heart disease, stroke and diabetes is now thought to be associated as much with the distribution of the excess fat as with the amount of excess fat. Fat distribution is usually measured in the population by the waist to hip circumference ratio (WHR). A high WHR seems to be a proxy measurement for an excess of intra-abdominal fat. Subcutaneous fat mass can be estimated using skinfold measurements. Exact determinations can only be performed directly using expensive equipment, such as computed tomography (CT). People with high WHR measurements can be said to have a 'central' fat distribution: people with low WHR measurements can be said to have a 'peripheral' fat distribution. 'Central' fat distribution carries most metabolic risks and is associated with a predisposition towards coronary heart disease, stroke, diabetes, breast cancer and gallstones. In some cases, the distribution of fat is a stronger risk factor than total obesity. 'Peripheral' fat distribution carries least metabolic risk. However, risks related to the mechanical problems of carrying excess fat, such as varicose veins, are increased. The risks of obesity therefore depend on the distribution of fat as well as total fatness.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Composition↗
PubMed1991

beta-deuterium kinetic isotope effects in the purine nucleoside phosphorylase reaction.

1. [2'-2H]Inosine was made from inosine by tetraisopropyldisiloxanyl protection of the 3'- and 5'-positions, oxidation with dimethyl sulphoxide and acetic anhydride, immediate NaB2H4 reduction of the oxo sugar product and inversion at C-2' of the resultant protected [2'-2H]arabino-inosine by trifluoromethanesulphonylation and reaction with caesium propionate, followed by deprotection. 2. The equilibrium-perturbation technique was used to measure beta 2H(V/K) for phosphorolysis of this compound by the purine nucleoside phosphorylase of Escherichia coli as a function of pH. 3. The pH variation indicates an intrinsic effect of 1.068 masked by isotopically silent steps near the pH optimum. 4. The similar pH variation of these beta-deuterium effects and the alpha-deuterium effects measured previously [Stein & Cordes (1981) J. Biol. Chem. 256, 767-772; Lehikoinen, Sinnott & Krenitsky (1989) Biochem. J. 257, 355-359] for this reaction provides the first experimental reassurance for the common assumption that pH changes merely mask and unmask the chemical steps in an enzyme-catalysed reaction, and do not detectably alter transition-state structure. 5. The dihedral angle between the C-H-2' bond and the electron-deficient p-orbital at the transition state is in the range 32-48 degrees, in accord with an essentially planar furanose ring.

Deuterium↗
PubMed1987

The synthesis of some branched-chain-sugar nucleoside analogues.

1-(2,3-Epoxy-5-O-trityl-beta-D-lyxofuranosyl)uracil was treated with a number of carbon nucleophiles. Ethynyl lithium gave 3'-deoxy-3'-ethynyl-5'-O-trityl-ara-uridine, which was reduced to the corresponding 3'-ethenyl compound. Sodium cyanide gave 3'-cyano-3'-deoxy-5'-O-trityl-ara-uridine which upon alkaline hydrolysis gave the corresponding 3'-carboxamido compound. 1,3-Dithian-2-yl lithium gave 3'-deoxy-3'-(1,3-dithian-2-yl)-5'-O-trityl-ara-uridine. The trityl group was removed from each of these compounds by mild acidic hydrolysis. Treatment of 2 with 0.1M H2sO4 and mercury (II) acetate afforded 3'-acetyl-3'-deoxy-ara-uridine which upon reduction with NaBH4 gave 3'-deoxy-3'-(1-hydroxyethan-1-yl)-ara-uridine. Acetylation of 6 yielded 5'-O-acetyl-3'-acetyl-2',3'-didehydro-2',3'-dideoxyuridine which upon reduction with NaBH4 produced a mixture of 5'-O-acetyl-2',3'-didehydro-2',3'-dideoxy-3'-(1-hydroxyethan -1-yl)uridine and 1-(R)[5-(S)-acetoxymethyl-4-(1-hydroxyethan-1-yl)-tetrahydrofuran- 2-yl]- uracil. Reduction of 14 with Raney nickel followed by removal of the trityl group gave 3'-deoxy-3'-methyl-ara-uridine.

Indicators and Reagents↗
PubMed1987

Decreased brown adipose tissue thermogenic activity following a reduction in brain serotonin by intraventricular p-chlorophenylalanine.

The effects of reducing brain serotonin (5-HT) levels by means of intracerebral-ventricular injections of the tryptophan antagonist p-chlorophenylalanine (PCPA) were investigated in male rats. Six days after the operation, PCPA-treated rats, either fed ad libitum or pair-fed to the food intake of control rats, showed decreased thermogenic activity and capacity in their interscapular brown adipose tissue (BAT) and also increased fat storage in their white adipose tissue (WAT). These results indicate that serotonergic synapses might play a regulatory role in the sympathetic control of BAT thermogenesis and in the rate of WAT deposition (by an as yet unidentified mechanism), in addition to their well established role in controlling food intake.

Adipose Tissue↗