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Biomedical subjects

R N Baumgartner

Publications and source records attributed to R N Baumgartner.

At least 91 records · Page 5Linked to original sources
PubMed1990

Body composition of humans: comparison of two improved four-compartment models that differ in expense, technical complexity, and radiation exposure.

Multicompartment models are of growing importance in the study of body composition in humans. This study compares two improved four-compartment (water, protein, mineral, and fat) models that differ in expense, technological complexity, and radiation exposure. Primary data (from 31 subjects) for the first model were derived by dual-photon absorptiometry, 3H2O dilution, and hydrodensitometry and for the second model by delayed and prompt gamma neutron-activation analysis and 3H2O dilution. Estimates of fat, protein, and mineral from the first model were highly correlated with those from the second model (r = 0.98, 0.72, and 0.94, respectively; all p less than 0.001). The proportions of body weight represented by water, protein, mineral, and fat for the simpler first model (0.532, 0.155, 0.048, and 0.265) were similar to compartment fractions provided by the more complex and costly second model (0.532, 0.143, 0.046, and 0.279). Multicompartment body composition models can thus be developed from increasingly available techniques that compare favorably with similar results derived from limited-access instrumentation.

Absorptiometry, Photon↗
PubMed1990

Evaluation of accuracy and reliability of calipers for measuring recumbent knee height in elderly people.

Height measurements in elderly individuals are frequently not feasible and stature must be estimated from knee height. This study compared the accuracy and reliability of a knee-height caliper developed by Ross Laboratories with Mediform and GPN models. Two observers measured 40 elderly ambulatory volunteers with each caliper. Knee height was measured on the left leg from the heel to a point 5 cm proximal to the patella. Intracaliper reliability was similar. Mean absolute differences between repeated measurements ranged from 0.17 to 0.25 cm, technical errors of the estimate ranged from 0.16 to 0.26 cm, and coefficients of reliability exceeded 0.99 for each model. Equations based on knee height predicted subjects' stature to +/- 2.3 cm, an amount unlikely to substantially impair height-based nutrition indices. This comparatively inexpensive caliper was as accurate and reliable as more expensive commercially available models and may be recommended as an alternative to the other calipers.

Age Factors↗
PubMed1990

Bioelectric impedance methods for the estimation of body composition.

The present use of bioelectric impedance is based upon the greater electrolyte content and conductivity of fat-free mass (FFM). The limitation of the whole body impedance approach may be the use of S2/R as an index of the conductive volume of the body. The use of body lengths that closely resemble the actual length of the conductor rather than stature can improve predictions of FFM. Theoretically, the specific resistivity approach to bioelectric impedance also provides a means of circumventing this problem. Another alternative is the estimation of whole body composition or the composition of body segments from measurements of the lengths and resistances of the segments and the use of the phase angle of the whole body and or body segments. Possible alternative methods for the use of bioelectric impedance would be the measurement of the composition of body segments, the determination of specific resistivities so that estimates of FFM can be calculated without the need for regression equations and the determination of the use of different current frequencies in measuring body composition with bioelectric impedance.

Body Composition↗
PubMed1989

Estimation of body composition from bioelectric impedance of body segments.

The hypothesis that body composition can be estimated accurately from measurements of the length and resistance of the body segments was tested. Weight; stature; whole-body resistance; and the resistances, lengths, and circumferences of the leg, trunk, and arm were measured for 135 white men and women aged 18-58 y. Fat-free mass (FFM) and percent body fat (%BF) were obtained from densitometry. The resistance of the whole body was determined almost entirely by the resistances of the arm and the leg. The accuracy of the prediction of FFM from arm length2/arm resistance and of %BF from weight x arm resistance/arm length2 was only marginally less than that obtained by using whole-body measurements. Thus, measurements of the resistance and length of the arm can be used in place of the whole-body methods for estimating body composition from bioelectric impedance.

Adipose Tissue↗
PubMed1989

Status of anthropometry and body composition data in elderly subjects.

Understanding the normal changes in the body and its composition with increasing old age and their health implications are important to the health care and nutritional support of elderly subjects. Distribution statistics for selected body measurements of persons aged 65-80 y are available from the national health surveys. Recumbent anthropometric techniques and B-mode ultrasound may be applicable to measuring those greater than 80 y who have difficulty standing or are chair- or bedfast. The problems of estimating body composition in elderly subjects could be improved by using a four-compartment model. Noninvasive methods, such as anthropometry and bioelectric impedance, could be used to predict body composition in elderly subjects if appropriate equations were available and validated against direct methods. The most pressing need is for the development of suitable reference data for anthropometry and body composition in large representative samples of black, white, Hispanic and Oriental elderly persons in the US.

Aged↗
PubMed1989

Associations between plasma lipoprotein cholesterols, adiposity and adipose tissue distribution during adolescence.

Associations between changes with age in 'fat pattern' and lipoprotein cholesterols during adolescence were analyzed using serial data for 214 boys and girls between 11 and 18 years of age who were participants in the Fels Longitudinal Study. The logarithms of the ratios of the subscapular to lateral calf and the subscapular to triceps skinfold thicknesses increased with age in each sex, but the increases were greater in the boys. Plasma levels of HDL cholesterol decreased with age in the boys, but not in the girls. Within annual age-groups, neither plasma LDL cholesterol nor HDL cholesterol were correlated with percent body fat or either of the 'fat pattern' indices in each sex. In 51 children with serial data 5 years apart, changes with age in HDL cholesterol had significant negative correlations with changes in the 'fat pattern' indices that were independent of changes in percent body fat in the boys, but not in the girls. In the girls, changes in the indices were due to greater increases in the thickness of the subscapular skinfold than in the triceps and lateral calf skinfolds as percent body fat increased and were not associated with changes in levels of plasma lipoproteins. In the boys, changes in the 'fat pattern' indices were due to decreases in the thicknesses of the lateral calf and triceps skinfolds and increases in thickness of the subscapular skinfold as percent body fat decreased. These results suggest that a redistribution of adipose tissue occurs during adolescence in boys and is associated with decreases in HDL cholesterol.

Adipose Tissue↗
PubMed1988

Bioelectric impedance phase angle and body composition.

The use of bioelectric impedance phase angle for predicting body composition was determined in 53 males and 69 females 9-62 y of age. The phase angle describes the amount of reactance (Xc) in a conductor relative to the amount of resistance (R). Bioelectric resistance (R) and reactance (Xc) were determined for the whole body and separately for arm, leg, and trunk. Weight, stature, and skinfold thicknesses were measured. Body composition was determined from densitometry. Phase angles for the trunk (phi t), leg (phi 1), and whole body (phi w) had significant (p less than 0.05) negative correlations with percent body fat (%BF) in each sex, and positive correlations with fat-free mass (FFM) in males. In multiple regression analyses, phi t was associated significantly with %BF after controlling for age, mean skinfold thickness, and weight/stature2 in each sex. Bioelectric phase angle for the trunk may be useful for predicting %BF in clinical and survey research.

Adipose Tissue↗
PubMed1988

Specific resistivity used to estimate fat-free mass from segmental body measures of bioelectric impedance.

This report provides estimates of specific resistivity for a sample of 123 children and adults aged 9-62 y. The mean muscle-specific resistivities for the upper and lower extremities (arm and leg) and trunk of these participants were used to compute estimates of fat-free mass (FFM) from the sum of the corrected total muscle conductive volumes of the arms, legs, and trunk. Mean values for predictions of FFM from S2/Z or from the product of total muscle conductive volume and the density of FFM were not significantly different from means of FFM estimated from body density by underwater weighing. This analysis demonstrates that an estimate of FFM can be obtained by summing the conductive muscle volumes of each body segment derived from the corresponding segment lengths squared, measures of bioelectric impedance, and mean muscle-specific resistivities. These mean estimates of FFM are not as accurate as mean predictions of FFM from S2/Z in regression equations.

Adipose Tissue↗
PubMed1988

Abdominal composition quantified by computed tomography.

Abdominal composition was quantified from computed tomography (CT) scans of 96 clinically normal men and women aged 20-83 y. Measurements were taken of total and intraabdominal areas and of muscle, bone, and subcutaneous and intraabdominal adipose-tissue areas from each of six 8-mm-thick transverse slices from CT images of abdomen and pelvis. Men had a significantly greater percentage of intraabdominal adipose tissue than women and the percentage increased with age in each sex. Percentages of total abdominal area that were adipose tissue were significantly negatively correlated with percentages of muscle and bone in each sex. Ratios of total areas of abdominal slices to total areas of pelvic slices (analogous to waist:hip ratios) had significant positive correlations with the absolute and relative areas of intraabdominal and subcutaneous adipose tissue for the abdomen in women but not in men. These ratios also had significant negative correlations with absolute and relative areas of muscle and bone in women.

Abdomen↗
PubMed1987

Fatness and fat patterns: associations with plasma lipids and blood pressures in adults, 18 to 57 years of age.

As a part of the Fels Body Composition Study (an extension of the Fels Longitudinal Study in Yellow Springs, Ohio), the hypothesis was examined that a centripetal fat pattern, characterized by a greater proportion of trunkal than extremity adiposity, was associated independent of age and per cent body fat with levels of plasma lipids and lipoprotein cholesterols and blood pressures. A cross-sectional sample of 303 white men and women, 18 to 57 years of age, measured between September 1976 and August 1979, was selected without regard to diagnosis of hypertension, hyperlipidemia, or obesity. The degree of centripetal adipose tissue distribution was indexed by the logarithm of the ratio of the subscapular to lateral calf skinfold thicknesses. Per cent body fat was estimated by densitometry. In multiple regression equations controlling for age, age2, and per cent body fat, centripetal fat pattern had a small but significant positive association with systolic blood pressure in men (R2 = 0.02, p less than 0.05). In women, centripetal fat pattern had small but significant positive associations with plasma triglycerides (R2 = 0.05, p less than 0.005), and a significant negative association with plasma high density lipoprotein cholesterol (R2 = 0.08, p less than 0.0005) after effects due to age, age2, and per cent body fat had been removed. Centripetal fat patterns appear to be associated with an "atherogenic" lipid profile in women, but the association in men is confounded with effects due to age and total body adiposity.

Adipose Tissue↗
PubMed1986

Incremental growth tables: supplementary to previously published charts.

Serial data from 818 normal white American children from the Fels Longitudinal Study have been used to construct tables of 6-mo increments for weight (0 to 18 yr), stature (3.0 to 18 yr), head circumference, and recumbent length (0 to 3 yr). The tables supplement previously published incremental growth charts. The attained growth status of these children has been shown to be very close to that displayed in the National Center for Health Statistics tables at all ages, and secular trends in the data have been shown to be minimal. Consequently, the present tables should be widely applicable for some time in the future. Guidelines for the use of the tables and interpretation of findings are presented.

Adolescent↗