Total Body Electrical Conductivity Research Articles

Body fat and fat-free mass in infants: new and classic anthropometric indexes and prediction equations compared with total-body electrical conductivity

Body fat and fat-free mass in infants: new and classic anthropometric indexes and prediction equations compared with total-body electrical conductivity

Comparison of Condition Indices in Migratory Passerines at a Stopover Site in Coastal Louisiana

We evaluated the utility of four nondestructive condition indices-body mass, body mass scaled by wing chord length, fat scoring, and total body electrical conductivity method (TOBEC) ― as predictors of lipid levels in migrating Wood Thrushes (Hylocichla mustelina), Swainson's Thrushes (Catharus ustulatus), and Summer Tanagers (Piranga rubra). The Red-winged Blackbird (Agelaius phoeniceus), a winter resident, was examined for comparative purposes. In addition, we examined differences among species in relationships of total body lipids and condition indices. Body mass was the best index of lipid levels, explaining 36%-82% of the variation in total body lipids in all four species. The relative contributions of the other indices to the prediction of lipid mass varied among species although TOBEC was selected for inclusion in each regression equation. For two species, equations including TOBEC measurements had lower errors in lipid prediction than equations only using the other nondestructive indices. Errors in lipid prediction were large for all the regression equations based on condition indices. In many cases it will be necessary to develop species-specific equations to predict lipid levels with condition indices

An evaluation of the use of total body electrical conductivity for the estimation of body composition in adult rats: effect of dietary obesity and adrenalectomy

An evaluation of the use of total body electrical conductivity for the estimation of body composition in adult rats: effect of dietary obesity and adrenalectomy

New way of body composition analysis using total body electrical conductivity method

Traditional methods of measuring total body water and fat content of animals that require sacrificing specimens are generally unacceptable when endangered species, or large animal sizes, or humans are involved. These methods are also unsuitable for following changes of fat and water content in individuals. An alternative method, based on the nonresonant absorption of a rf electromagnetic field has been used for constructing a new body composition analyzer. As the electrical conductivity of lipids is approximately 20 times lower than that of lean tissues, the rf power absorbed by the animal provides information which enables one to calculate the lean body mass and total body water. The new instrument measures rf power absorbed by an animal by measuring the quality factor (Q) of the resonant circuit with an animal placed inside the coil. Numerical calculations of the rf power absorbed by a cylindrical object containing 0.9% NaCl aqueous solution have also been performed. Experimental values confirmed the calculated dependence of the absorbed power on the cylinder radius. The device built has been calibrated on 9 males and 11 females of laboratory mice. The amount of lipids was then measured by ether extraction. The relation between instrument reading, which is proportional to the power absorption, and lean body mass (LBM) or water mass (WM) was linear and highly significant: the simple regression coefficients of determination were 0.983 for LBM, and 0.990 for WM (p<0.001). It has been found that for an individual animal with a body mass ranging from 15.9 to 40.7 g, the accuracy of measurement was ±1.6 g for LBM and ±1 g for WM.

Comparison of TOBEC-derived total body fat with fat pad weights

Comparison of TOBEC-derived total body fat with fat pad weights

Evaluation of a Noninvasive Technique for Measuring Fat-Free Mass in Poultry

Evaluation of a Noninvasive Technique for Measuring Fat-Free Mass in Poultry

Childhood obesity: pathophysiology and treatment.

Childhood obesity is among the most difficult problems which pediatricians treat. It is frequently ignored by the pediatrician or viewed as a form of social deviancy, and blame for treatment failure placed on the patients or their families. The definition of obesity is difficult. Using total body electrical conductivity (TOBEC) technology, total body fat ranges between 12% and 30% of total body weight in normal children and adolescents. This is influenced not only by age, but also by physical fitness. Anthropometry is the easiest way to define obesity. Children whose weight exceeds 120% of that expected for their height are considered overweight. Skinfold thickness and body mass index are indices of obesity that are more difficult to apply to the child. Childhood obesity is associated with obese parents, a higher socioeconomic status, increased parental education, small family size and a sedentary lifestyle. Genetics also clearly plays a role. Studies have demonstrated that obese and non-obese individuals have similar energy intakes implying that obesity results from very small imbalances of energy intake and expenditure. An excess intake of only 418 kJ per day can result in about 4.5 kg of excess weight gain per year. Small differences in basal metabolic rate or the thermic effects of food may also account for the difference in energy balance between the obese and non-obese. In the Prader Willi Syndrome, there appears to be a link between appetite and body fatness. When placed on growth hormone, lean body mass increases, body fat decreases, sometimes to normal, and appetite becomes more normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative assessment of infant body fat by anthropometry and total-body electrical conductivity

Quantitative assessment of infant body fat by anthropometry and total-body electrical conductivity

Influence of Early Feeding Mode on Body Composition of Infants

To determine the effect of infant feeding mode on body composition, a cross-sectional study was designed in which 10 breast-fed and 10 formula-fed infants were studied at 1 month of age, and another 10 breast-fed and 10 formula-fed infants at 4 months of age. Anthropometric measurements included body weights, lengths, selected diameters, circumferences and skinfold thicknesses. Total body water (TBWO) was measured by 18O dilution. A dose equivalent to 300 mg 18O/kg body weight was administered orally to the infants. Fat-free mass (FFMO) was calculated from TBWO using reference hydration constants of 0.805 and 0.798 at 1 and 4 months, respectively. Body fatO was taken as the difference between weight and FFMO. Total-body electrical conductivity (TOBEC) measurements were used to estimate FFMT and FATT. ANOVA was used to analyze the anthropometric and body composition data using feeding mode and age as grouping factors. Anthropometric measurements did not differ by feeding mode. TBW (kg) and FFM (kg) and body fat (kg) derived from 18O dilution or TOBEC did not differ by feeding mode. TBWO,T (%wt), FFMO,T (%wt), and body fatO,T (%wt) derived from 18O dilution and TOBEC differed significantly between the breast-fed and formula-fed infants at 4 months of age (p < 0.05). Expressed as a percentage of body weight, TBWO and FFMO,T were higher and body fatO,T was lower among the 4-month formula-fed infants.

Total Body Electrical Conductivity Measurements: An Evaluation of Current Instrumentation for Infants

Quantitation of the body's fat and learn masses is an important component of nutritional assessment. Such measurements, however, are difficult to conduct routinely in infants due to the numerous limitations of traditional methods. The application of total body electrical conductivity measurements for quantitating fat-free mass (FFM) overcomes many of these limitations. The instruments required to perform these measurements in pediatric patients (HP-2) have recently become commercially available, but their measurement performance has not been evaluated. In these studies, we compared the precision, day-to-day variability, and magnetic field profile of three HP-2 instruments. We also derived a new calibration equation that relates the FFM to the total body electrical conductivity measurement in piglets, and compared it with an equation (provided currently by the manufacturer) derived on a prototype instrument. The performance of the instruments was generally similar, although a significant difference in the magnetic field of one instrument was identified. The coefficient of variation of inanimate phantom measurements varied from +/- 0.2 to +/- 0.5%, and the day-to-day variability was generally similar. Such measurement error is significant (+/- 0.035 to +/- 0.078 kg FFM) for small subjects. The new calibration equation was similar to the original equation; therefore, all the data were pooled to generate a new equation that is linear at least to 10 kg. Thus, the HP-2 total body electrical conductivity instruments, which can be safely and easily used to measure FFM and fat in infants through 1 y of age, proved to be reliable and precise, and results obtained from different instruments can be confidently compared.

Maternal Obesity and Body Composition of the Neonate

Obese women generally deliver heavier infants, but the body composition of these infants is unknown. The principal objective of this study was to determine if neonates of obese women have more adipose tissue. At 35-36 weeks of gestation, a fasting blood sample was collected from 37 pregnant women. Shortly after birth, the body fat of the neonates was measured with an infant total-body electrical conductivity (TOBEC) instrument using a prediction equation derived from 10 miniature pigs. At 6 weeks post partum, the infant body fat was measured a second time, and the body fat of each mother was measured using an adult TOBEC instrument. We found no differences between the obese (n = 16) and lean subjects (n = 21) in the concentrations of glycerol, beta-hydroxybutyrate, triglyceride, total cholesterol, high-density lipoprotein cholesterol, or glucose in the blood. However, the insulin concentration was elevated in the obese women (199 +/- 57 pmol/l) as compared with the lean women (128 +/- 68 pmol/l, p < 0.01). At birth, maternal adiposity (% body fat) was significantly associated with infant adiposity (r = 0.37, p < 0.05). However, by 6 weeks post partum the association no longer existed. Multiple regression analysis showed that maternal adiposity, fasting glucose level, and gestational age are independently associated at birth with infant adiposity.

Accuracy and reliability of total body electrical conductivity (TOBEC) for determining body composition of rats in experimental studies

Accuracy and reliability of total body electrical conductivity (TOBEC) for determining body composition of rats in experimental studies

Total Body Electrical Conductivity for Nondestructive Measurement of Body Composition of Red Drum

Total Body Electrical Conductivity for Nondestructive Measurement of Body Composition of Red Drum

Copper Deficiency Shifts Energy Substrate Utilization from Carbohydrate to Fat and Reduces Fat Mass in Rats

Copper Deficiency Shifts Energy Substrate Utilization from Carbohydrate to Fat and Reduces Fat Mass in Rats

Evaluation of Lipid Indices of the Wood Thrush

Many techniques for assessing lipid reserves have been used, but techniques are seldom evaluated. We evaluated five common methods (fat scoring, regression residuals of body mass vs. morphological measurements, quotients of body mass divided by morphological measurements, total body electrical conductivity, and water content) for assessing lipid reserves in the Wood Thrush (Hylocichla mustelina) in Rhode Island. Lipid content ranged from 3 to 1 l%, water content ranged from 64 to 72%, and fat score ranged from 0 to 4. Mean total body electrical conductivity (TOBEC) was moderately correlated with lean body mass. Percentage water and fat score were highly correlated with extracted lipid mass and percentage lipid content. Body mass, tail x mass regression residuals, and quotient of body mass/tail length were highly correlated with lean body mass. Morphological measurements were correlated with lean mass only when in association with body mass, but not considered alone. Combining TOBEC readings with body mass and morphological measurements produced regression models with similar predictive abilities as previous studies using TOBEC, but TOBEC provided little or no additional predictive ability. TOBEC did not significantly improve body fat predictive models and does not appear accurate in predicting lipid mass of individual small birds. Fat score and percentage water are useful indices of body fat in Wood Thrush.

The effect of alterations in physical and chemical characteristics on TOBEC-derived body composition estimates: validation with non-human models

The measurement of total-body electrical conductivity (TOBEC) has become one of the standard methods for the estimation of body composition in infants. The authors investigated, using nonhuman models, the effect on the accuracy of TOBEC-derived body composition estimates of alterations in physical and chemical characteristics of the fat-free mass (FFM). The effect of electrolyte type, concentration and volume on TOBEC was determined using 2, 3 and 5 l solutions of 6 different chlorides and sodium bicarbonate. Equimolar concentrations yielded TOBEC values in accordance with known ion conductivities: H+>>Ca2+>Mg2+>K+>Na+>Li+ and Cl->HCO3-. The behaviour of these solutions was described very accurately over a wide range of concentrations (1-200 mM) by a simple exponential law. Dissolved egg-white protein, glycine and L-glutamine elicited no TOBEC signal. In vitro, using polyethylene bottles filled with physiologic saline, in the interval of 2-45 degrees C a linear relation was observed between temperature and TOBEC. Below the freezing point no TOBEC signal was elicited. The effect of tissue autolysis and body temperature on TOBEC was examined by repeated measurements of TOBEC and temperature in 7 fresh infant minipig cadavers. Five minipigs were allowed to cool. Shortly after death TOBEC decreased by 2.5% per degrees C. Two Animals were kept at constant temperature. The TOBEC signal showed a gradual increase of 9% after 7 h due to autolysis. It is concluded that in vivo TOBEC measurements are affected by ion concentration (e.g. nonisotonic hydration changes), geometry (e.g. deviations in body shape), temperature (e.g. fever, skin cooling) and tissue autolysis (measurements after death). Proteins, molecules with strong dipole moments and ions trapped in crystalline structures do not significantly affect the TOBEC reading.

Electromagnetic scanning to predict lamb carcass composition.

The electromagnetic scanner generates a constant, low-level electromagnetic field (2.5 MHz) within a large plexiglass tube. The amount of electromagnetic (EM) energy transferred (to the carcass) is highly related to lean tissue. A plot of the absorption units over distance can be used to assess the total mass of lean tissue and of the respective primal cuts. The difference in curve height between two points (D), peak phase absorption, and linear carcass measurements (pre-rigor, HCWT or post-rigor, CWT carcass weight, and carcass length, LENG) were used to predict total dissected lean (TOTLEAN), dissected leg lean (LEGLEAN), and percentage of dissected carcass lean (PERLEAN). Twenty-one pre-rigor and 22 post-rigor (24 h chill) lamb carcasses, average weight 26.8 (+/- 4.2 kg) and 26.4 (+/- 4.1 kg) kg, respectively, were evaluated from measurements of total body electrical conductivity (TOBEC). Two geometric orientations were tested for statistical accuracy in this study: A) each carcass entered the EM tunnel rear leg first, on its left lateral side, neck facing the right side of the tunnel; and B) each carcass entered the EM tunnel rear leg first, breast down, and neck up. Orientation A proved more statistically efficient for pre-rigor carcasses, and orientation B was more desirable for post-rigor carcasses. Multiple-regression models involving HCWT, LENG, and a single D measure accounted for 98.0 and 95.0%, respectively, of the total variation in pre-rigor carcass TOTLEAN and LEGLEAN in A.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of growth hormone administration and treadmill exercise on the body composition of rats.

The aim of this study was to compare the effects of growth hormone administration and treadmill exercise on bone mass, body fat mass, and fat-free mass. Forty female rats aged 14 mo were divided into control, ovine growth hormone administration (0.5 mg.kg-1.day-1; GH), treadmill exercise (17 m/min, 60 min/day; EX), and EX + GH groups. Noninvasive total body electrical conductivity and dual X-ray absorptiometry techniques were used to assess the body fat content, fat-free mass, and tibial and L4 vertebral bone mineral content of each experimental animal at weeks 0, 9, and 16. The age-related increase in body fat mass was suppressed in the GH group, and the fat-free mass and L4 bone mass were higher in the GH group than in the control group. Conversely, in the EX group there was no gain in body fat mass and no significant change in fat-free mass or vertebral bone mass. The tibial bone mass increased in both the GH and EX groups; however, the time response to the two interventions appeared to differ. In the EX + GH group there was no further enhancement of the anabolic effect on the tibial bone mass. The effect of growth hormone administration on body fat content and bone mass is distinct from that of treadmill exercise.

Annual and Daily Variation in Body Mass and Fat of Starlings Sturnus vulgaris

Seasonal and daily variation in body mass and fat was monitored in Starlings Sturnus vulgaris and related to the different phases of the annual cycle, to changes in temperature and daylength, and to Lehikoinen's (1987) models for body mass regulation of wintering birds. Lean mass and fat were estimated using total body electrical conductivity (TOBEC) and a combined fatscore index for the abdominal and furcular visible fat-depots. With the fatscore, lean mass and fat were estimated better (R2 = 0.89 and 0.92, respectively) than with Walsberg's (1988) interspecific TOBEC (R2 = 0.56 and 0.75), or our intraspecific Starling TOBEC (R2 = 0.56 and 0.82). Lean mass for both sexes decreased over the breeding season, increased again during the first half of moult, and remained constant for the rest of the year (males 75 g and females 71 g). Seasonal changes in reserves and absolute amounts of fat were similar in males and females (8 g in winter and 2 g during moult). In early spring, female lean mass and fat increased by 7 g and 4 g, respectively, so that early in the breeding season females were 5 g heavier than males. Outside the breeding season, females were 4 g lighter than males. Evening body mass and fat were negatively correlated with the mean temperature of the preceding two to four weeks. During the whole year, nightly mass loss fluctuated between 5 and 6 g. Of the two conditions of the ''true winter fattening model'' (Lehikoinen 1987), namely an increase of dawn body mass and of the amplitude of the daily mass cycle, only the first one was supported.

Food Restriction Effects on the Body Composition of Free-Living Ground Squirrels,Spermophilus beldingi

I conducted a field experiment to examine the use of body fat as an energy reserve by juvenile female Belding's ground squirrels, Spermophilus beldingi, prior to hibernation. Squirrels were divided into two groups: the squirrels in one group had their foraging times restricted by being placed in a cage for part of each day for four consecutive days (deprived group), and the squirrels in the other group foraged ad lib. (ad lib. group). The deprived group foraged in its normal habitat morning and evening but had access only to water and lettuce while captive. Total body electrical conductivity (TOBEC), an in vivo method of estimating fat-free mass, was used to follow changes in body composition. The deprived group lost mass, while the ad lib. group gained mass. Total body electrical conductivity measurements indicated that the deprived group lost fat-free mass and not fat, whereas mass gained by the ad lib. group was mostly fat. This is consistent with an emphasis on fat anabolism prior to hibernation. I also show that the TOBEC method is affected by variation in stomach contents, and I evaluate conditions under which an intraspecific calibration equation is needed