Seiichi Yasumura

Comparative skeletal mass and radial bone mineral content in black and white women

The age-related changes in both skeletal mass and muscle mass were directly measured in normal black women ages 30-80 yr. The levels of total-body calcium (TBCa) were determined with the use of in vivo neutron activation. The muscle mass was measured by wholebody counting of 40K. In the same population, the bone mineral content of the radius was measured using a photon absorptiometric technique. Although there was no significant difference in stature, black women had a greater skeletal mass and bone mineral content of the radius than age-matched white female subjects. When the TBCa values were normalized for body size (i.e., corrected for height and lean body mass), the TBCa was still higher for the black women but not as high as the absolute TBCa values. Clearly, it is the larger muscle mass (as reflected by the 40K measure) in relation to weight and height that accounts for this difference. The lower prevalence of fracture and osteoporosis observed in black women relative to white women is due in part to this greater quantity of skeleton. American black women with a higher bone density (i.e., skeletal mass) maintain mechanical integrity of the skeleton longer than individuals with a lower bone density. It is suggested that the larger muscle mass in black women is, in part, a determinant of their increased skeletal mass and is partly responsible for their apparent resistance to osteoporosis and fracture of the skeleton.

Compartmental body composition of cancer patients by measurement of total body nitrogen, potassium, and water

Quantitative measurement was made of body composition in patients with several forms of neoplastic disease. Total body nitrogen was determined by means of the prompt gamma neutron activation technique; total body potassium was measured with the use of a whole body counter. The mass and protein content of the muscle compartment and nonmuscle lean tissue were estimated by application of the technique of compartmental analysis. Total body water, determined simultaneously with the use of tritium label, provided a measure of lean body mass. From these data, the body fat can be inferred. The prompt gamma neutron activation and whole body counting techniques represent a considerable advance over the balance and radioisotope techniques used in earlier studies. The new techniques make possible sequential studies over prolonged periods of time with a considerable degree of accuracy. The loss of body weight by patients with solid tumors consisted primarily of the loss of muscle mass and body fat. Even in severe wasting, the patients appear to retain significant amounts of body fat. It is the skeletal muscle which is predominantly lost; the visceral life-supporting system is, to a considerable extent, spared. The nonmuscle tissue including the visceral fraction did not change in this study, and actually appeared to increase in size when comparison was made with the normal contrast population. The loss of total body water was slight in the cancer patients studied.

Body composition and surgical treatment of obesity. Effects of weight loss on fluid distribution.

Obesity is associated with absolute and relative expansion of the extracellular water compartment (ECW). The effects of substantial and prolonged weight reduction on body water distribution are unknown, however. The authors studied total body water (TBW) by tritiated water dilution, ECW by 35SO4 dilution, exchangeable sodium (Na(e)) by 24Na, and total body potassium (TBK) by 40K whole-body counting in 25 severely obese women (body mass index [BMI] = 48 +/- 7 kg.m-2, mean +/- standard deviation) aged 36 +/- 8 years before and at intervals after gastric restrictive (GR; n = 12) and malabsorptive (MA; n = 13) operations for obesity. Results are compared with a control group of 26 healthy normal-weight women (BMI = 21 +/- 2). Before operation, the obese patients had absolute elevations of all water compartments compared with controls, with significantly higher ratios of Na(e) to TBK (1.17 +/- 0.13 versus 0.91 +/- 0.10; p less than 0.05) and ECW to intracellular water (ICW) (E/I = 0.82 +/- 0.17 versus 0.63 +/- 0.06; p less than 0.05). After weight loss of 52 +/- 20 kg in MA and 47 +/- 19 kg in GR patients (nonsignificant between groups) to a stable level 22 +/- 8 months after operation, there were statistically significant reductions in TBW, ICW, TBK, and Na(e) in both groups, but a significant reduction in ECW only after GR. Adjusting for preoperative weight, duration of follow-up, and rate of weight loss, E/I was greater after MA than GR (1.09 +/- 0.25 versus 0.82 +/- 0.14; p less than 0.05). The elevated preoperative E/I ratio did not normalize with weight loss after surgery, and the response was related to the type of operation. The finding remains to be explained although the increased E/I after MA may reflect mild protein-calorie malnutrition not detectable in the blood. The persistence of elevated E/I with significant weight loss after GR might imply an intrinsic or irreversible imbalance of fluid distribution in obese patients.

The skeletal calcium/phosphorus ratio: A new in vivo method of determination

We describe a new method for assessing the Ca/P ratio of bone in vivo using gamma-ray photon absorptiometry. The theoretical approach of the method and the estimation of the variance are presented. Two radiation sources, Gd-153 (100 keV), and I-125 (27.5 keV), and a germanium detector were used to determine this ratio. Measurements were made on bone phantoms with different Ca/P ratios; also, the ratio was measured on lamb and sheep tibias, rabbit tibias, and human fingers. Since the accuracy of the method is affected by the amount of fat and collagen in the measurement field, the effect of collagen and fat on the measurements also was investigated. In all cases, the precision of the method, expressed as the coefficient of variation (CV): 100x standard deviation/mean, was near to the theoretical one, ranging from 1.8% to 3.2%. For human fingers, the CV was 3.2%, a value near to the theoretical 2.9% with a dose to the skin ranging from 0.044 to 0.066 mGy, depending on the width of the finger.

Changes in body composition of cancer patients following combined nutritional support

The effects of combined nutritional support (parenteral, enteral, and oral) were measured in cancer patients unable to maintain normal alimentation. Changes in body composition were quantified by measurement of total body levels of nitrogen, potassium, water, and fat. The protein-calorie intake of the patients was also evaluated by dietary survey (4-day recall). Standard anthropometric and biochemical measurements for nutritional assessment were obtained for comparison. The dietary evaluation indicated that the dietary supplementation for all patients was more than adequate to meet their energy requirements. Almost all patients gained weight on the combined nutritional support regimens. Determination of body composition indicated that change in body weight was equal to the sum of the changes in body protein, total body water, and total body fat. The findings from the anthropometric nutrition indices (arm muscle circumference and triceps skinfold) were consistent with the results of the body composition study. Information on the nature of the tissue gained was obtained by comparison of body composition data with the ratio of protein:water:lean body mass for normal tissue. The mean gain of protein in the cancer patients was quite small (0.3-0.6 kg). The main change in body weight appeared to be the result of gains in body water and body fat. The total body nitrogen to potassium ratio served to define the extent of tissue anabolism following hyperalimentation. The ratio dropped in the cancer patients following hyperalimentation toward the value of the control subjects on ad libidum diets. The body compartment techniques described have demonstrated their usefulness in determining the effects of hyperalimentation on cancer patients.

Body composition and aging: a study by in vivo neutron activation analysis.

Human body composition can be organized into five levels; atomic, molecular, cellular, tissue-system and whole body. Six elements (carbon, nitrogen, calcium, potassium, sodium and chlorine) can be directly measured in vivo at the atomic level using three neutron-activation systems at Brookhaven National Laboratory. When combined with an estimate of total body water, the six elements can be used to quantify the major chemical components at molecular level. In the present report, we first describe the neutron-activation approach to evaluating chemical compartments in vivo. Then, we present an example of how in vivo estimates of human chemical composition can be used to study the validity of two-compartment indirect methods of quantifying total body fat in the elderly. Our studies and the work of other investigators at Brookhaven National Laboratory suggest that neutron activation analysis provides an important opportunity to study the relation between aging and changes in elemental and chemical composition of humans in vivo.

The effects of inflammation-mediated osteoporosis (IMO) on the skeletal Ca/P ratio and on the structure of rabbit bone and skin collegen

The relationships between the skeletal Ca/P ratio (used as an index of bone quality) and structural changes in the bone and skin was studied in inflammatory mediated osteoporosis (IMO). The bone Ca/P ratio in IMO rabbits was significantly lower than in controls. Also, severe alterations were detected at the ultrastructural level in bone and skin collagen fibrils from IMO rabbits.

Calibration for measuring total body nitrogen with a newly upgraded prompt gamma neutron activation facility

A description is given of the calibration and performance of the upgraded facility at Brookhaven National Laboratory (BNL) for measuring total body nitrogen using the technique of prompt gamma neutron activation analysis. With the improved calibration, total body nitrogen can be more accurately measured not only in normal subjects but also in obese and wasted patients. Body hydrogen is used as an internal standard. We examined the effect of a heavy-water premoderator on the uniformity of composite sensitivity, nitrogen and hydrogen measurement statistics, and dose to the subject. The calibration technique corrects the ratio of nitrogen-to-hydrogen counts measured from the subject for body size. Additionally, a correction for subcutaneous adipose tissue on the nitrogen-to-hydrogen count ratio is introduced. The newly upgraded BNL facility provides precision in counting statistics using a Remcal anthropomorphic phantom filled with a tissue-equivalent solution of 2.1% for a body dose of 0.35 mSv using a 2.5 cm D2O premoderator. The measurements were made at five 20 cm sections, counting for 200 s per section.

Performance of the Delayed- and Prompt-Gamma Neutron Activation Systems at Brookhaven National Laboratory

Brookhaven National Laboratory (BNL) is one of the major facilities pioneering the development of in vivo neutron activation (IVNA) techniques for body composition studies. The IVNA facility at BNL includes a delayed- and prompt-gamma neutron activation system (DGNA and PGNA), as well as an inelastic neutron scattering facility (INS). The BNL DGNA system was first fully established in the 1960’s by Cohn et al. (1969). It is composed of a total-body neutron activation facility (TBNAF) and a whole body counter (WBC), and is used to measure total body sodium, phosphorus, chlorine, and calcium. Body potassium is measured by counting endogenous 40K with the whole body counter. The PGNA system to measure total body nitrogen (TBN) was developed by Vartsky et al. (1979), and the INS system to measure total body carbon (TBC) was instituted by Kehaiyas et al. (1987). The DGNA and PGNA facilities have been upgraded and modified since they were first built.

Women at risk for developing osteoporosis: Determination by total body neutron activation analysis and photon absorptiometry

SummaryWith stepwise multiple logistic regression (MLR), probabilistic classification equations were developed to identify asymptomatic women who are at risk for development of fracture of the spine. Clinically normal women with low TBCa/