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Biomedical subjects

A L Bailey

Publications and source records attributed to A L Bailey.

29 records · Page 2Linked to original sources
PubMed1995

Nutrient intake and biochemical status of non-instutionalized elderly subjects in Norwich: comparison with younger adults and adolescents from the same general community.

The Department of Health (1992) has recently stated that 'Nutritional reviews concerning elderly people are especially constrained by lack of data', and that much of the emphasis in the nutritional literature has been placed on the study of institutionalized, and often chronically ill, elderly subjects rather than the non-institutionalized elderly who form the majority of this population. The present study presents information on the dietary intake and biochemical status of non-institutionalized elderly subjects (68-73 and 74-90 years) and compares such data with those obtained for adult (20-64 years) and adolescent (13-14 years) populations living within the same community. Nutrient intakes and appropriate biochemical measurements of nutrient status, performed on fasting blood samples, were statistically examined and have been discussed in relation to potential age-related influences. The nutrient intake of elderly subjects was on a par with adolescents of corresponding sex but generally lower than that of adult counterparts. There were several significant differences in biochemical measurements of nutrient status between age groups. In general these did not suggest progressive age-related trends. However, there were significant suggestions of age-related increases in whole-blood glutathione peroxidase (EC 1.11.1.9) activity, serum ferritin, plasma cholesterol, LDL and triacylglycerol concentrations and decreases in plasma HDL and ascorbic acid concentrations. The significance of these differences is discussed. An age-related difference (suggestive of a decline) in vitamin C status together with a difference (suggestive of an increase) in glutathione peroxidase activity may indicate an imbalance in the regulation of O2-derived free-radicals with ageing. These observations are worthy of a further study in the light of current thinking which relates the induction of a number of diseases to oxidative damage.

Adolescent↗
PubMed1994

Modulation of membrane fusion by asymmetric transbilayer distributions of amino lipids.

The fusion of model lipid bilayers containing synthetic amino lipids and the regulation of this fusion by inducing transbilayer asymmetry of these amino lipids via imposed pH gradients are demonstrated. Liposomes of 100 nm diameter consisting of 5 mol% 1,2-dioleoyl-3-(N,N-dimethylamino)propane (AL1) in a mixture of egg phosphatidylcholine (EPC), dioleoylphosphatidylethanolamine (DOPE), and cholesterol in a ratio of 35:20:45 do not fuse at pH 4.0. Fusion also is not observed upon increasing the external pH of these vesicles to 7.5, which results in the rapid transport of AL1 to the inner monolayer, as measured by a fluorescent probe sensitive to surface charge. However, dissipation of the imposed pH gradient leads to redistribution of AL1 to the outer monolayer at pH 7.5 and causes liposomal fusion, as detected by fluorescent lipid-mixing assay and freeze-fracture electron microscopy. The effect of varying the hydrocarbon structure of AL1 on the rate of fusion is demonstrated with five synthetic analogues, AL2-AL6. Higher rates of fusion occur with lipids containing longer unsaturated acyl chains and with lower values of pKa for the membrane-bound amino lipids. Fusion is also associated with destabilization of the bilayer at pH 7.5, as indicated by the formation of the hexagonal HII phase.

Fluorescent Dyes↗
PubMed1994

Thiamin intake, erythrocyte transketolase (EC 2.2.1.1) activity and total erythrocyte thiamin in adolescents.

The relationships between thiamin intake, erythrocyte transketolase (EC 2.2.1.1) activity coefficient (ETK-AC) and total erythrocyte thiamin were investigated in a group of adolescents (13 to 14 years old; nineteen boys, thirty-five girls). Thiamin intakes were calculated from 7 d weighed records, using food composition tables, and compared with those obtained by direct analysis of duplicate diets. Average 7 d calculated thiamin intakes were significantly lower than analysed intakes for both sexes. On an individual basis, calculated intakes ranged from 30 to 143% of corresponding analysed values. Analysed and calculated intakes were significantly correlated when expressed as mg/d; however, when expressed in terms of energy intake, the correlation was significant for males only. Thiamin intake appeared largely adequate when compared with current UK dietary recommendations (Department of Health, 1991), but the limitations of such comparisons are considered. The major food groups contributing to thiamin intake were examined and showed breakfast cereals to contribute more than 25% of dietary thiamin. A proportion of the subjects had ETK-AC values in ranges usually associated with marginal or severe thiamin deficiency. There was, however, no statistically significant relationship between erythrocyte thiamin and basal or stimulated transketolase activity, or between thiamin intake and either of the methods used to assess status. The need to re-evaluate indices of thiamin status is discussed.

Adolescent↗
PubMed1994

Dietary intake and micronutrient status of adolescents: effect of vitamin and trace element supplementation on indices of status and performance in tests of verbal and non-verbal intelligence.

Relationships between micronutrient intake and status, and micronutrient status and performance in tests of intelligence were investigated in a group of adolescents (13-14 years old). Dietary intakes were assessed using a 7 d weighed dietary record method, coupled with the collection of duplicate diets. Vitamin and trace mineral intakes calculated using food composition tables were compared with those obtained by direct analysis of duplicate diets. Micronutrient status was judged via a range of biochemical indices measured in blood samples taken after a 12-15 h fast. Blood samples were taken both before and after a 16-week period of vitamin and trace mineral supplementation. Individual tests of verbal and nonverbal intelligence were also performed pre- and post-supplementation. The results of this study indicate that the use of food table data may lead to substantial over- or underestimation of the intake of several micronutrients. In general, the total calculated or analysed amount of a specific micronutrient consumed did not adequately predict status, as judged by a range of biochemical indices. There were significant changes in status measurements over the 16-week study period, irrespective of supplementation, and these changes were markedly influenced by the initial status of the subject. There was no effect of supplementation on performance in tests of intelligence. However, there was a significant association between plasma ascorbic acid and initial non-verbal intelligence quotient (IQ) in the boys, and between whole blood glutathione peroxidase (EC 1.11.1.9) activity and non-verbal and verbal IQ in both sexes. These findings are discussed in relation to other recent studies of the influence of micronutrient supplementation on the psychological performance of children.

Adolescent↗
PubMed1990

Thiamine status of healthy and institutionalized elderly subjects: analysis of dietary intake and biochemical indices.

Thiamine status was assessed in healthy young and elderly subjects and institutionalized elderly patients by measuring dietary intake, erythrocyte levels of thiamine and the activity of the thiamine-dependent enzyme, erythrocyte transketolase, with and without the addition of excess thiamine pyrophosphate (the TPP effect). Healthy elderly subjects had a reduced intake of thiamine compared with the younger subjects but erythrocyte levels of thiamine and the TPP effect were comparable, suggesting adequate thiamine status. The institutionalized elderly patients had a low intake of thiamine compared with the healthy elderly as well as abnormal biochemical indices suggestive of suboptimal thiamine status. Thiamine deficiency does not appear to be a problem in healthy elderly people but those in institutions are at risk of deficiency which might adversely affect their clinical state.

Adult↗