Comparison of air-displacement plethysmography with hydrostatic weighing and bioelectrical impedance analysis for the assessment of body composition in healthy adults. (73/12479)

BACKGROUND: Over the past decade, considerable attention has been paid to accurately measuring body composition in diverse populations. Recently, the use of air-displacement plethysmography (AP) was proposed as an accurate, comfortable, and accessible method of body-composition analysis. OBJECTIVE: The purpose of this study was to compare measurements of percentage body fat (%BF) by AP and 2 other established techniques, hydrostatic weighing (HW) and bioelectrical impedance analysis (BIA), in adults. DESIGN: The sample consisted of healthy men (n = 23) and women (n = 24). %BF was measured by AP, HW, and BIA. RESULTS: In the total group, %BF(AP) (25.0+/-8.9%) was not significantly different from %BF(HW) (25.1+/-7.7%) or %BF(BIA) (23.9+/-7.7%), and %BF(AP) was significantly correlated with %BF(HW) (r = 0.944, P < 0.001) and with %BF(BIA) (r = 0.859, P < 0.01). Compared with HW, AP underestimated %BF in men (by -1.24+/-3.12%) but overestimated %BF in women (by 1.02+/-2.48%), indicating a significant sex effect (P < 0.05). The differences in estimation between AP and BIA and between BIA and HW were not significantly different between the sexes. CONCLUSION: AP is an accurate method for assessing body composition in healthy adults. Future studies should assess further the cause of the individual variations with this new method.  (+info)

Four-component model of body composition in children: density and hydration of fat-free mass and comparison with simpler models. (74/12479)

BACKGROUND: Body composition in children is generally measured by 2-component (2C) models, which are subject to error arising from variation in fat-free mass (FFM) composition. The 4-component (4C) model, which divides body weight into fat, water, mineral, and protein, can overcome these limitations. OBJECTIVE: The aims of our study were to 1) describe 4C model data for children aged 8-12 y; 2) evaluate interindividual variability in the hydration, bone mineral content, and density of FFM; 3) evaluate the success with which 2C models and bedside techniques measure body composition in this age group with use of the 4C model as a reference. DESIGN: Dual-energy X-ray absorptiometry, underwater weighing, deuterium dilution, bioelectrical impedance analysis, and anthropometry were used to determine body composition in 30 children. The contribution of methodologic error to the observed variability in the hydration and density of FFM was evaluated by using propagation of error. RESULTS: Mean (+/-SD) FFM density and hydration were 1.0864+/-0.0074 kg/L and 75.3+/-2.2%, respectively, and were significantly different from adult values (P < 0.02). Relative to the 4C model, deuterium dilution and dual-energy X-ray absorptiometry showed no mean bias for fatness, whereas underwater weighing underestimated fatness (P < 0.025). Fatness determined by using skinfold-thickness and bioelectrical impedance analysis measurements along with published equations showed poor agreement with 4C model data. CONCLUSIONS: Biological variability and methodologic error contribute equally to the variability of FFM composition. Our findings have major implications for bedside prediction methods used for children, traditionally developed in relation to underwater weighing.  (+info)

Relation between body fat and age in 4 ethnic groups. (75/12479)

BACKGROUND: Previous studies of the relation between age and body fat reached differing conclusions concerning the question of whether body fat is lower in the elderly than in middle-aged persons. OBJECTIVE: The objectives of this study were to characterize the relation between age and body fat in 4 ethnic groups and test the hypothesis that body fat is lower in the elderly than in middle-aged persons. DESIGN: Body fat was measured in a sample of 1324 volunteers aged 20-94 y by using a 4-component model of body composition. Four ethnic groups were studied: Asians, blacks, Puerto Ricans, and whites. Regression models were developed for fat mass and fat percentage as functions of age. RESULTS: In all but one of the groups, a highly significant curvilinear relation between age and body fat was found, indicating a peak amount of body fat in late middle age and lower amounts of body fat at younger and older ages (P < 0.001). The age at which maximum body fat was predicted in the various groups ranged from 53 to 61 y for fat mass and from 55 to 71 y for fat percentage. In Puerto Rican men there was no significant relation between age and fat mass, and the relation between age and fat percentage was linear and positively correlated. CONCLUSIONS: This study provided data on the relation between age and body fat in 4 ethnic groups and supported the hypothesis that body fat is lower in the elderly than in middle-aged persons.  (+info)

Body composition in renal transplant patients: bioimpedance analysis compared to isotope dilution, dual energy X-ray absorptiometry, and anthropometry. (76/12479)

Whether multifrequency bioelectrical impedance analysis (MF-BIA), a relatively new method for measuring body composition, is also applicable for accurate body composition measurements in renal transplant (RTx) patients is not known. Therefore, the use of MF-BIA is validated in 77 RTx patients with a stable renal function at least 2 yr posttransplantation. MF-BIA is compared to isotope dilution techniques for measurement of body water compartments, and to dual energy x-ray absorptiometry (DEXA) and anthropometry for measurement of fat and fat free mass. Finally, DEXA and anthropometry are compared to each other. Method agreement is assessed by intraclass correlation coefficients (ICC) and plotted by Bland and Altman analysis. MF-BIA significantly underestimates total body water (TBW, 0.7+/-2.1 L) and overestimates the extracellular water (ECW, 3.3+/-1.8 L) compared to isotope dilution; the ICC between both techniques is 0.943 for TBW and 0.846 for ECW. The percentage body fat (BF) measured by MF-BIA is significantly higher than both BF measured by DEXA (3.4+/-4.7%) or by anthropometry (5.5+/-5.2%). The ICC between MF-BIA and DEXA is 0.887 and between MF-BIA and anthropometry 0.856. BF measured by DEXA is significantly higher than BF measured by anthropometry (2.1+/-4.4%); their ICC is 0.913. In conclusion, MF-BIA seems to be suitable for measurement of TBW in RTx patients; however, method agreement between isotope dilution and MF-BIA for the measurement of ECW is not satisfactory. In the assessment of fat and fat free mass, the reliability of MF-BIA appears to be questionable. Method agreement between DEXA and anthropometry seems to be slightly better.  (+info)

Partial purification and characterization of a triglyceride lipase from pig adipose tissue. (77/12479)

A triglyceride lipase was extracted from defatted pig adipose tissue powder with dilute ammonia and purified about 230-fold by a combination of ammonium sulfate fractionation, heparin-Sepharose 4B, DEAE-cellulose, and Sephadex G-150 column chromatographies and isoelectrofocusing electrophoresis. The enzyme was distinguishable in physical and kinetic properties from the two previously defined lipases in adipose tissue, lipoprotein lipase, and hormone-sensitive lipase. The purified enzyme was fully active in the absence of serum lipoprotein and was not stimulated by adenosine 3':5'-monophosphate-dependent protein kinase. In marked contrast to the already defined lipases, the enzyme was strongly inhibited by serum albumin. The enzyme had a molecular weigt of about 43,000, a pI of 5.2, and pH optimum of 7.0. The enzyme hydrolyzed triolein to oleic acid and glycerol, and did not exhibit esterase activity. The apparent Km for triolein was 0.05 mM. Physiological roles of this new species of lipase remained to be explored.  (+info)

Induction of lipogenesis during differentiation in a "preadipocyte" cell line. (78/12479)

3T3-L1 fibroblasts differentiate in culture into cells having adipocyte character. This transition is accompanied by a 40- to 50-fold rise in the incorporation of [14C]acetate into triglyceride. The increase in lipogenic rate is exactly parallel to a coordinate rise in the activities of the key enzymes of the fatty acid biosynthetic pathway (ATP-citrate lyase, acetyl-CoA carboxylase, and fatty acid synthetase). Immunological studies indicate that the elevated acetyl-CoA carboxylase activity is the product of an increased cellular enzyme level.  (+info)

Ecdysone-inducible functions of larval fat bodies in Drosophila. (79/12479)

Late in the third instar larval stage of Drosophila melanogaster, the titer of the steroid hormone ecdysone increases sharply. This increase is blocked in the temperature-sensitive mutant ecd(1) after a temperature shift from 20 degrees C to 29 degrees C. The mutant was used to prepare three samples of late third instar larvae with different titers of ecdysone; the titer was low in one sample because of an earlier temperature shift, high in a second sample because the larvae were subsequently transferred to ecdysone-supplemented food, and also high in a third sample that was kept at 20 degrees C, providing a control for normal development. The effect of the high titer of ecdysone on proteins of the larval fat bodies was examined by comparing two-dimensional gel electrophoresis patterns of total proteins in stained gels. There were proteins at five positions in the gels for the high-ecdysone samples that were not detected at the corresponding positions in the gel for the low-ecdysone sample. The effect of ecdysone on these proteins was further studied by injecting [(35)S]methionine into the larvae at both early and late third instar stages, in order to label proteins synthesized before and after the increase in ecdysone titer. The results indicate that ecdysone induces two major responses in the fat bodies; certain proteins that were synthesized earlier in the fat bodies and secreted into the hemolymph are incorporated back into the fat bodies, and other proteins are newly synthesized. Attempts to induce prematurely the synthesis of the new proteins by exposing early third instar larvae to exogenous ecdysone were unsuccessful, suggesting that development must proceed further before the fat bodies can respond to ecdysone. By in vitro translation of RNA isolated from fat bodies of low-and high-ecdysone samples of larvae, it was shown that ecdysone greatly increases the amount of translatable messenger RNA for one of the newly synthesized proteins. A clone of DNA complementary to the induced messenger RNA has been isolated from a population of lambda bacteriophage carrying segments of the Drosophila genome. Using the cloned DNA to measure amounts of complementary poly(A)-RNA in the fat bodies by DNA.RNA hybridization, we detected about 50 times more complementary poly(A)-RNA in the high-ecdysone sample of larvae than in the low-ecdysone sample. This finding provides direct evidence that ecdysone induces an increase in the amount of the messenger RNA. The ecdysone-induced appearance of a major messenger RNA in late third instar larval fat bodies represents a developmental response to ecdysone that appears to be gene-specific, tissue-specific, and stage-specific, and it has exceptionally favorable features for further molecular studies of the control of gene expression by a steroid hormone.  (+info)

MR appearance of rhinoscleroma. (80/12479)

BACKGROUND AND PURPOSE: We describe the MR imaging appearance of rhinoscleroma, an endemic, chronic, granulomatous disease whose causative agent is Klebsiella rhinoscleromatis. METHODS: The study included 15 patients (nine males and six females; mean age, 25 years; range, 13-36 years) with rhinoscleroma. MR imaging was performed in all patients. The signal intensity of the nasal masses was compared with that of fat, muscle, and CSF on both T1- and T2-weighted images. All cases were proved by histopathologic examination. RESULTS: The nasal masses were bilateral and symmetrical (n = 6), asymmetrical (n = 4), or unilateral (n = 5). They extended through the anterior nares (n = 9) or posterior choana into the nasopharynx (n = 3). They obstructed the ostiomeatal units with retained secretions in the related sinuses (n = 10). On T1-weighted images, rhinoscleroma showed striking (n = 9) or mild (n = 6) high signal intensity relative to muscle and CSF, but less hyperintensity than fat. On T2-weighted images, the nasal masses showed homogeneous high signal intensity (n = 10) or heterogeneous high signal intensity associated with hypointense foci (n = 5). They were hyperintense relative to fat and muscle, but less hyperintense than CSF. CONCLUSION: The hypertrophic stage of rhinoscleroma has characteristic mild to marked high signal intensity on both T1- and T2-weighted MR images.  (+info)