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Biomedical subjects

P Paxton

Publications and source records attributed to P Paxton.

5 recordsLinked to original sources
PubMed1996

Components of total energy expenditure in free-living elderly men (over 75 years of age): measurement, predictability and relationship to quality-of-life indices.

Current recommendations for energy requirements in the elderly are based on assumed levels of physical activity relative to BMR (1.5 x BMR). The main aim of the present study was to establish whether these recommendations might be applicable to a randomly-selected group of free-living elderly men (all over 75 years of age). BMR was measured by indirect calorimetry and total energy expenditure (TEE) by the doubly-labelled-water technique. Further aims included evaluating the applicability of a variety of BMR prediction equations and whether assessed quality of life reflected any measured indices of energy expenditure. The mean value for daily energy requirement was found to be 1.5 x BMR (89 J/kg per min) but with substantial inter-individual variation (sd 0.2 x BMR; 14 J/kg per min). The bias between measured TEE and TEE estimated (1.5 x BMR) from the various BMR predictions varied according to which equation was used (-10- + 8% of the mean) with substantial 95% limits of agreement (28-30% of the mean). TEE and physical activity plus thermogenesis (TEE-BMR) were positively related to activities of daily living, but no relationships were apparent between these and perceived quality of life. It is concluded that, despite considerable inter-individual variability, national recommendations for energy requirements of elderly people are applicable to this randomly-selected group of free-living men over 75 years of age but that substantial variation exists when attempts are made to estimate TEE from measurements or predictions of BMR.

Activities of Daily Living↗
PubMed1993

Screening for HIV and hepatitis B virus in Los Angeles County prenatal clinics: a demonstration project.

A project designed to pilot voluntary screening for HIV antibody and hepatitis B virus antigen (HBsAg) in women using Los Angeles County Department of Health Services prenatal clinics is described. The purpose of the study was to demonstrate that HIV testing could be integrated into an existing prenatal health care system with minimal disruption. In an 8-month period, 9,069 women entered the project; 76% accepted HIV antibody testing. The rate of HIV antibody seropositivity was 144 per 100,000 (10 per 6,943), and the rate of HBsAg seropositivity was 253 per 100,000 (23 per 9,103). No difference in test acceptance rates was found using a sign-off versus a sign-on HIV antibody consent form although potential confounders were not controlled. Only five of the eight HIV antibody-positive women (63%) and eight of the 20 HBsAg-positive women (40%) who were interviewed reported behaviors considered high risk for HIV or HBsAg infection.

Adult↗
PubMedDate not supplied

Prediction of body composition in elderly men over 75 years of age.

A comprehensive number of body composition predictions (involving weight, height, skinfold thicknesses, bioelectrical impedance and near-infrared interactance-NIRI) were evaluated against total body water (TBW from isotope dilution), in 23 randomly selected men over 75 years old, and dual-energy X-ray absorptiometry (DXA), in 15 volunteers from this group. Comparisons were made between anthropometric and impedance methods for estimating limb muscle mass (obtained using DXA). Bias and 95% limits of agreement between measured TBW and DXA estimates were -2.1 kg and 3.1 kg, respectively (for fat, 5.4% and 6.1% body weight). Agreement between TBW predictions and reference measurements was remarkably variable, irrespective of whether TBW was predicted from TBW-specific equations or indirectly from estimates of fat or fat-free mass: for predictions using anthropometry, bias ranged from -4.7 kg to 1.6 kg and 95% limits of agreement from bias +/- 3.8 kg to +/- 5.0 kg; using impedance, bias was -8.8 kg to 3.2 kg and 95% limits of agreement were bias +/- 3.6 kg to +/- 7.8 kg; corresponding values for NIRI were -5.3 kg and +/- 5.4 kg. Although some non-age-specific equations appeared valid, age-specific equations generally predicted TBW better. Limb muscle mass (DXA) was predicted better using the segmental impedance method, from indices of limb muscle area (r = 0.76; SEE = 1.9 kg) and volume (r = 0.86; SEE = 1.6 kg), than by anthropometry alone (r = 0.61 and 0.71; SEE = 2.3 kg and 2.1 kg, respectively). In conclusion, some body composition predictions are unacceptable (at least for TBW) in older men, and care is recommended when selecting from these methods or equations. Also, the segmental impedance method is as good as, if not better than, anthropometry alone in predicting limb muscle mass (DXA) in older men.

Absorptiometry, Photon↗