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Abrahamsen, B.; Hansen, T.B.; Hogsberg, I.M.; Pedersen, F.B.; Becknielsen, H. Impact of hemodialysis on dual X-ray absorptiometry, bioelectrical impedance measurements, and anthropometry Journal American Journal of Clinical Nutrition Dual X-ray absorptiometry (DXA) performs noninvasive assessment of bone and soft tissue with high precision. However, soft tissue algorithms assume that 73.2% of the lean body mass is water, a potential source of error in fluid retention. We evaluated DXA (model QDR-2000; Hologic Inc, Waltham, MA), bioelectrical impedance analysis (BLA), and simple anthropometry in 19 patients (9 women and 10 men, mean age 46 y) before and after hemodialysis, removing 0.9- 4.3 L ((x) over bar: 2.8 L) of ultrafiltrate. The reduction in fat-free mass (FFM) measured by DXA was highly correlated with the ultrafiltrate, as determined by the reduction in gravimetric weight (r = 0.975, P < 0.0001; SEE: 233 g), whereas BLA was considerably less accurate in assessing FFM reductions (r = 0.66, P < 0.01; SEE: 757 g). Lumbar bone mineral density (BMD) was unaffected by dialysis, as were whole-body fat and BMD. Whole-body bone mineral content, however, was estimated to be 0.6% lower after dialysis. None of the simple anthropometric measurements correlated significantly with the reduction in FFM. In an unmodified clinical setting, DXA appears to be superior to other simple noninvasive methods for determining body composition, particularly when the emphasis is on repeated measurements. |
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Armellini, F.; Scalfi, L.; Zamboni, M.; Castelli, S.; Mino, A.; Bosello, O. Relationship between hydration of lean body mass and visceral adipose tissue. A clinical study of women OBJECT: To study the relationship between hydration of lean body mass and adipose tissue location. DESIGN: Cross-sectional, clinical study of visceral adipose tissue area and total body water as a percentage of lean body mass. PATIENTS: Seventy-two adult, overweight, women, 52 pre- and 20 post-menopausal (age: 18-72 years, body mass index: 26- 52). MEASUREMENTS: Total body water was obtained by electrical impedance measurement; visceral adipose tissue and lean body mass were obtained by computed tomography measurement of visceral adipose tissue area at the level of the 4th-5th lumbar vertebra. RESULTS: Visceral adipose tissue was found, by multiple regression analysis, to be the only predictor of thehydration of the lean body mass. The other independent variables: age, menopausal status, body mass index. glucose and insulin both fasting and after glucose load were not able to significantly improve the predictive power. CONCLUSION: Results of this study confirm the existence of a relationship between visceral adipose tissue content and hydration of the lean body mass. |
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Arpadi, S.M.; Wang, J.; Cuff, P.A.; Thornton, J.; Horlick, M.; Kotler, D.P.; Pierson, R.N. |
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Arslanian, S.; Suprasongsin, C. Insulin sensitivity, lipids, and body composition in childhood: Is ''syndrome X'' present? Syndrome X, or the syndrome of insulin resistance, is a cluster of related metabolic abnormalities of hyperinsulinemia, glucose intolerance, increased very low density lipoprotein (VLDL), decreased high density lipoprotein (HDL), and hypertension in nonobese adults and plays an important role in the genesis of cardiovascular disease. The aim of the present study was to examine the relationships among insulin sensitivity, plasma lipid levels, and body composition in the paediatric age group to determine whether these associations are present in childhood. Twenty healthy Caucasian Tanner stage I (TI) children (age, 10.7 +/- 0.3 yr; body mass index, 18.9 +/- 0.8 kg/m(2)) and 22 pubertal. Tanner stage II-IV (TII-IV) adolescents (age, 14.0 +/- 0.3 yr; body mass index, 20.0 +/- 0.4 kg/m(2)) were studied. In vivo insulin-mediated glucose disposal (Rd) was evaluated during a 40 mu/m(2). min hyperinsulinemic-euglycemic clamp. Body composition was assessed isotopically by the (H2O)-O-18 dilution principle. Fasting blood was obtained for cholesterol, triglyceride (TG), VLDL, low density lipoprotein (LDL, and HDL determinations. In both groups, the strongest correlation of Rd was with percent body fat (%BF) (TI: r = -0.82; P < 0.001; TII-IV: r = -0.73; P < 0.001). In addition, in TI, Rd was correlated with TG (r = 0.64; P = 0.001), VLDL (r = 0.64; P = 0.001), and diastolic blood pressure (r = -0.50; P = 0.01). There were no such correlations in TII-IV. In TI, %BF correlated positively with LDL and negatively with TG and VLDL. In TII- IV, %BF correlated positively with cholesterol and LDL. After correcting for %BF, partial correlation analysis revealed no relationship between Rd and lipid levels in either group. This suggests that the relationship of insulin sensitivity to lipid levels was secondary to theeffect of body composition on lipid levels. However, regardless of body composition, the basal insulin level was correlated with TG (r = 0.38; P = 0.04) and VLDL (r = 0.40; P = 0.04) in TII-IV subjects. We conclude that 1) the primary correlate of insulin sensitivity is %BF in both prepubertal and pubertal subjects, with no relationship to plasma lipids; 2) in prepubertal children, diastolic blood pressure is negatively correlated with insulin sensitivity and positively with insulin levels, independent of adiposity; and 3) after the onset of puberty, basal insulin levels are positively correlated with VLDL and TG regardless of the degree of adiposity. This observation could be a very early manifestation of the genesis of syndrome X in childhood. |
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Avis, N.J.; Barber, D.C. Incorporating a priori information into the Sheffield filtered back projection algorithm The Sheffield image reconstruction algorithm is based on the assumption that the initial conductivity distribution of the body being imaged is uniform. In many situations this assumption is violated. Previous attempts at incorporating a priori information by modifications to the backprojection matrices were ineffective. An alternative method of including a priori information became apparent |
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Avis, N.J.; Barber, D.C. Incorporating a priori information into the Sheffield filtered backprojection algorithm The Sheffield image reconstruction algorithm is based on the assumption that the initial conductivity distribution of the body being imaged is uniform. In many situations this assumption is violated. Previous attempts at incorporating a priori information by modifications to the backprojection matrices were ineffective. An alternative method of including a priori information became apparent following the recent reformulation of the Sheffield image reconstruction algorithm. Applying matrix algebra to the image reconstruction equations reveals that the incorporation of a priori information can be considered as either a modification to the original backprojection matrix or a component of a composite data filter. A simple two-dimensional model of the adult head was chosen to test this approach. The results of imaging studies using synthetic data derived from this model show that a priori information has been successfully incorporated into the image reconstruction process. The ability to include a priori information into the image reconstruction process may have significant implications for the more challenging applications of Err such as imaging the adult head. |
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Avis, N.J.; Lindow, S.W.; Kleinermann, F. In vitro multifrequency electrical impedance measurements and modelling of the cervix in late pregnancy Idiopathic preterm labour is the greatest single perinatal problem occurring in an unpredictable 6-8% of all pregnancies and accounting for 75% of all perinatal deaths. Preterm cervical softening is used clinically as an important indicator of cervical dysfunction but the subjective nature of present clinical assessment methods prevents reliable prediction of preterm labour. This paper reports the finding of a pilot investigation concerned with obtaining quantitative measurements of the in vitro electrical impedance of the cervix using a four-electrode multifrequency impedance measurement system. Impedance measurements obtained from six samples of cervical tissue taken from different subjects at caesarean section were fitted to the Cole equation and parameters derived to describe the ratio of extra- versus intracellular impedance and the characteristic frequency. Subjects at term display a lower extra- versus intracellular impedance ratio than the preterm subjects. This appears consistent with the expected increase in the hydration of the cervix approaching term and the resulting decrease in the extracellular impedance. Further studies are required to determine if multifrequency electrical impedance tomography could be used as a non-invasive screening test for preterm labour. |
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Azcue, M.P.; Zello, G.A.; Levy, L.D.; Pencharz, P.B. Energy expenditure and body composition in children with spastic quadriplegic cerebral palsy Objective: To determine the relationship between resting energy expenditure and body cell mass in a group of children with spastic quadriplegic cerebral palsy (SQCP) in comparison with a group of healthy volunteers. Subjects and methods: Children with SQCP (n = 13) and healthy control subjects (n = 21) participated in the study. Resting energy expenditure (REE) by indirect calorimetry, as well as body composition measurements were obtained. Those included skinfold measurements, isotope dilution methods far total body water and extracellular water ((H2O)-H-2 or (H2O)-O-18 and NaBr, respectively), and bioelectrical impedance analysis. Intracellular water was calculated as total body water minus extracellular water. Results: Overall REE in children with SQCP was significantly less than in control subjects or from predicted World Health Organization equations. There was a poor correlation between REE and weight or height for children with SQCP and those for control subjects. Children with SQCP skewed a higher variance and small improvement in the correlation between REE and lean body mass or intracellular water in comparison with control subjects. Nine of the thirteen children with SQCP had significantly seduced REE per unit of lean tissue or intracellular water. Furthermore, bioelectrical impedance analysis was validated against dilution methods as a suitable technique for measuring total body water (r(2) = 0.90, r = 0.95) and extracellular water (r(2) = 0.84, r = 0.92) in children with SQCP. Conclusion: REE in children with SQCP is poorly correlated with body cell mass. We postulate that the central nervous system plays a crucial role in energy regulation. In children with SQCP, individual energy expenditure should be measured so that optimal nutritional status can be achieved. Bioelectrical impedance analysis can be used in this population to measure body water spaces. |