Evaluation of multi-frequency bioelectrical impedance analysis for the assessment of body composition in individuals with obesity.

OBJECTIVE: The purpose of this study was to compare body composition measurements estimated by multi-frequency bioelectrical impedance analysis (MF-BIA) with air displacement plethysmography (ADP) in individuals with obesity. METHODS: Bariatric patients were recruited from Geisinger's Center for Nutrition and Weight Management Clinic in Danville, Pennsylvania. Sixty-two participants (age = 52.4 ± 9.3 years; body mass index = 38.9 ± 8.0 kg m-2) reported for a same-day testing visit. Body composition was measured using a common MF-BIA analyzer (InBody 720, Biospace Co., Beverly Hills, CA) and ADP. RESULTS: Strong relationships were observed between MF-BIA and ADP methods (r = 0.88-0.96, P < 0.001). There were no differences between MF-BIA and ADP measures of per cent body fat, fat mass or fat-free mass for the total sample or when examined by gender. CONCLUSIONS: The InBody 720 MF-BIA analyzer produced body composition measurements that were similar to ADP supporting the use of this technology in the obese population.

The effect of a meal on measures of impedance and percent body fat estimated using contact-electrode bioelectrical impedance technology.

BACKGROUND/OBJECTIVES: To determine the effect of a meal on impedance and percent body fat (%BF) determined using contact-electrode bioelectrical impedance analysis (BIA) technology. SUBJECTS/METHODS: Forty-three adults (23 women and 20 men) volunteered to participate in this study (age=20.5±1.1 years; body mass index=24.1±3.8 kg/m(2)). Body composition was assessed using three BIA analyzers: leg-to-leg (LBIA), segmental (SBIA) and multi-frequency (MFBIA), on two separate occasions. After a baseline measurement, subjects consumed a meal or received nothing, which served as the control (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each condition. RESULTS: Twenty minutes after eating (3847±900 kJ), body mass (LBIA=0.8 kg, SBIA=0.8 kg, MFBIA=0.7 kg, P<0.05), impedance (LBIA=6.0 Ω, SBIA=17.9 Ω, MFBIA=27.1 Ω, P<0.05) and %BF (LBIA=0.9%, SBIA=1.7%, MFBIA=0.8%, P<0.05) increased significantly and remained elevated at 60 min POST. During the CON trial, a consistent body mass reduction (60-80 g) and impedance increase (4-9 Ω) was observed over time resulting in a small increase in %BF (0.3-0.7%) 60 min POST (P<0.05). CONCLUSIONS: Twenty minutes after eating, %BF increased due to elevations in impedance and body mass. As such, when precision is critical, we recommend adhering to the pretest fasting guidelines to avoid meal-induced alterations in %BF estimates. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.

Effect of mode selection when using contact-electrode bioelectrical impedance analyzers to estimate percent body fat in young adults.

AIM: When using bioelectrical impedance analysis (BIA) analyzers to assess body composition, a computer-programmed prediction equation referred to as a mode (i.e., standard STD or athletic ATH) must be selected prior to the assessment. This study examined the effect of mode selection on percent body fat (%BF) determined by leg-to-leg and segmental bioelectrical impedance analysis (LBIA; SBIA) in young adults. METHODS: Ninety-two young adults (52 women; 40 men) had %BF estimated using LBIA (Tanita: TBF-300A) and SBIA (Tanita: BC-418) which was then compared to air displacement plethysmography (ADP). During the BIA assessment, %BF was determined using both the STD and ATH pre-programmed modes. RESULTS: In the women, %BF (mean±SD) was significantly (P<0.001) underestimated by the ATH modes of LBIA (23.0±6.9%) and SBIA (23.4±6.2%) when compared to ADP (25.5±7.3%). In the men, the STD mode of LBIA (18.3±5%) overestimated %BF when compared to ADP (14.1±7%). All standard error of estimate and pure error values (range=3.8% to 6.3%) exceeded the recommended range for accuracy (<3.5%). CONCLUSION: The STD mode produced mean %BF values most similar to ADP in the women, whereas the ATH mode did so in the men; a finding that was consistent for both analyzers. However, large individual prediction errors and wide confidence intervals were observed regardless of the mode selected or analyzer used for the assessment. As such, when precision is critical, the prediction equations programmed in the LBIA and SBIA analyzers examined in this study cannot be recommended to measure %BF on an individual basis.

The effect of acute fluid consumption on measures of impedance and percent body fat estimated using segmental bioelectrical impedance analysis.

BACKGROUND/OBJECTIVES: To determine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) estimated using segmental bioelectrical impedance analysis (SBIA). SUBJECTS/METHODS: Seventy-six healthy, recreationally active adults (41 women; 35 men) volunteered to participate in this study (mean+/-s.d.; age, 21.0+/-1.6 years; body mass index, 25.0+/-3.2 kg/m2). Subjects had their body composition assessed on three separate occasions. After a baseline measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE) or received nothing (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each fluid condition. RESULTS: Twenty minutes after drinking a H2O or CHOE beverage, %BF (1.1 and 1.2%), impedance (12 and 14 Omega) and body mass increased significantly (P<0.001). During the CON trial, %BF (0.3 and 0.5%) and impedance (7 and 11 Omega) also increased significantly above baseline values at 40 and 60 min POST. However, the normal hourly variability was significantly (P<0.009) less than the observed fluid-induced %BF alterations. The greatest %BF increases were observed in the lightest subjects, who were women. Fluid type had no effect on the magnitude of change POST. CONCLUSIONS: Twenty minutes after drinking, %BF estimates increased approximately 1.0% due to elevations in impedance and body mass. As such, we recommend adhering to the pretest fluid restriction guideline to avoid fluid-induced alterations in SBIA body composition measures. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.

Effect of a maximal treadmill test on percent body fat using leg-to-leg bioelectrical impedance analysis in children.

AIM: The purpose of this investigation was to determine the effect of a maximal treadmill exercise test on percent body fat (%BF) in children using leg-to-leg bioelectrical impedance analysis (LBIA) (Tanita Model #TBF-300A). METHODS: Fifty-four children (24 females; 30 males) between 7-10 years of age participated in this study. LBIA measures of %BF were obtained immediately before and within 5 min after completing a maximal oxygen consumption test on a motorized treadmill. RESULTS: No pre- to post-test differences in %BF were observed in either group (mean difference: females 1.6%, males 1.5%). Impedance values significantly decreased postexercise (P < 0.05) in the female subjects. No significant differences were observed for fat mass, fat free mass, total body water or body weight postexercise when compared to pre-exercise values in either group. Correlations (P = 0.0001) of 0.997 were observed between pre- and postexercise measures of %BF. CONCLUSIONS: A maximal treadmill exercise test conducted prior to LBIA has no impact on %BF in children. Therefore, normal daily activities performed prior to LBIA assessment may have a limited impact on LBIA body composition measurement in children. As such, compliance with stringent pretesting exercise guidelines may not be essential when using LBIA to assess %BF in children.

Effect of mode selection when using leg-to-leg BIA to estimate body fat in collegiate wrestlers.

AIM: When using leg-to-leg bioelectrical impedance analysis (LBIA) to examine body composition, a computer-programmed mode (i.e., standard STD or athletic ATH) must be selected prior to assessment. This study examined the effect of LBIA mode selection on the estimated %BF of collegiate wrestlers. METHODS: Forty hydrated (Usg <1.02) wrestlers had %BF estimated using the ATH mode, which was then compared to the STD mode and hydrostatic weighing (HW), used as the reference method. Mean difference from HW (MD), standard error of estimate (SEE), and pure error (PE) values were calculated for the entire sample and three data subsets according to body mass index (BMI, kg/m(2)): <25 (n=16), 25-29.9 (n=18), and >30 (n=6). RESULTS: The %BF (mean+/-SD) was underestimated by the ATH (12.1+/-4.7) and overestimated by the STD (17.1+/-5.2) mode when compared to HW (14.1+/-6.3) for the entire sample (P<0.05). When examined relative to BMI, the ATH mode accurately estimated %BF in the BMI <25 group (MD=-1.2%, SEE=2.7%, PE=2.8%) and the STD mode accurately estimated %BF in the BMI >30 group (MD=1.5%, SEE=2.4%, PE=2.8%). Both modes inaccurately assessed %BF in the BMI 25-29.9 group with predictive errors >3.5%BF. CONCLUSIONS: The ATH mode is not appropriate for all individuals meeting the definition of athletic. However, the predictive accuracy of LBIA may be improved by selecting the ATH mode when BMI <25 and the STD mode when BMI >30, even when testing athletes.

The effect of acute fluid consumption on measures of impedance and percent body fat using leg-to-leg bioelectrical impedance analysis.

OBJECTIVE: To examine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) using a common leg-to-leg bioelectrical impedance analyzer system. DESIGN: Cross-sectional design with treatment order determined using a counterbalanced assignment. SETTING: University laboratory. SUBJECTS: In total, 21 recreationally active men (mean age 19.7 +/- 1.0 years; body mass index 24.2 +/- 2.3 kg/m2) volunteered to participate in this study. INTERVENTION: Subjects had their body composition assessed on three separate occasions. After an initial baseline body composition measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE), or received nothing, used as the control (CON). Subjects were reassessed 20, 40, and 60 min after baseline (POST). Urine specific gravity (USG) was recorded at baseline and 60 min POST to assess hydration state. RESULTS: There were no significant changes in impedance or total body water (TBW) for any of the measurement time periods after drinking H2O or a CHOE beverage. Body weight (BW) (P < 0.0001) and %BF (P < 0.02) increased significantly 20 min POST and remained elevated at the 40 and 60 min POST time periods. After drinking, USG significantly decreased (P<0.0001) 60 min POST from baseline. For the CON trial, there were no significant changes in BW, %BF, TBW, or USG over time. CONCLUSIONS: Fluid consumption had no effect on lower-body impedance despite causing significant changes in hydration state. A slight overestimation in %BF (approximately 0.5%) was observed due to increased BW in the H20 and CHOE trials. This finding may have little practical significance when assessing body composition by LBIA.

In vitro transformation by adenovirus-simiam virus 40 hybrid viruses. IV. Properties of clones isolated from cell lines transformed by adenovirus 2-simiam virus 40 and adenovirus 12-simiam virus 40 transcapsidant hybird viruses.

Clones were isolated from hamster cells transformed by the adenovirus 2-SV40 and adenovirus 12-SV40 transcapsidant hybrid viruses. The clones were characterized with respect to their cytomorphology, virus and antigen content, and the histomorphology of tumors induced by transplantation of the clonal sublines to hamsters. Three different cellular and colonial morphologies were observed. Clones with an SV40 morphology gave rise to tumors predominantly with an SV40 histology, whereas clones with an adenovirus morphology produced typical adenovirus tumors upon transplantation of the transformed cells. Clones which had features of both SV40 and adenovirus transformed cells gave rise to "intermediate" and adenovirus tumors. The results indicate that multiple events occur during transformation and tumorigenesis by the transcapsidant virus populations and provide an explanation for the multiplicity of findings which have been reported with these virus populations.

In vitro transformation by the adenovirus-simian virus 40 hybrid viruses. V. Virus-specific ribonucleic acid in cell lines transformed by the adenovirus 2-simian virus 40 and adenovirus 12-simian virus 40 transcapsidant hybrid viruses.

The ribonucleic acid-deoxyribonucleic acid hybridization technique was utilized to determine the presence of adenovirus (ad) and SV40 genetic information and to determine which ad genomes were present in clones of hamster cells transformed with the ad 2-SV40 and ad 12-SV40 transcapsidant hybrid virus populations. The results were correlated with the morphology of the transformed cells and colonies. It was found that cells transformed by either transcapsidant virus which had an SV40 morphology contained the ad 7 and SV40 genomes, whereas cells with a typical ad morphology contained only ad genetic information. Cells and colonies with morphological features of both ad- and SV40-transformed cells contained either the ad 2, or ad 12 genomes, depending on the transcapsidant used, together with the ad 7 and SV40 genomes. The results indicate the following: at least three different events occurred during transformation of hamster cells by the transcapsidant virus populations; the morphology of the resulting clones is determined by the viral genome(s) present; the linkage of the ad 7-SV40 genomes is confirmed since the ad 7- SV40 genomes were never found to be dissociated; the defective ad 7-SV40 genomes are capable of causing transformation; and the transcapsidant particle is probably composed of only ad 7 and SV40 genetic information.