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Biomedical subjects

D Vartsky

Publications and source records attributed to D Vartsky.

At least 37 records · Page 2Linked to original sources
PubMed1981

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.

Adipose Tissue↗
PubMed1981

Effects of methandienone on the performance and body composition of men undergoing athletic training.

1. In a previous study of the effects of methandienone (Dianabol) on men undergoing athletic training, strength and performance increased, but not significantly more when the subjects were taking the drug than when they were taking placebo. The subjects did, however, gain more weight on the drug, with increases in total body potassium and muscle dimensions. It remained an open question whether the muscles had gained normal tissue or intracellular fluid. 2. In an attempt to distinguish between these possibilities the trial has been repeated, using as subjects seven male weight-lifters in regular training, and including measurements of total body nitrogen. As before, a dose of 100 mg of methandienone/day was given alternately with the placebo in a double-blind crossover experiment. The treatment periods lasted 6 weeks and were separated by an interval of 6 weeks. Body weight, potassium and nitrogen, muscle size, and leg performance and strength increased significantly during training on the drug, but not during the placebo period. 3. The finding of increased body nitrogen suggested that the weight gain was not only intracellular fluid. The increases in body potassium (436 +/- SEM 41 mmol) and nitrogen (255 +/- 69 g) were too large in proportion to the weight gain (2.3 +/- 0.4 kg) for this to be attributed to gain of normal muscle or other lean tissue, and imply gain of nitrogen-rich, phosphate-poor substance. Although this action of methandienone might be described as anabolic, the weight gain produced is not normal muscle.

Adult↗
PubMed1981

Critical concentrations of cadmium in human renal cortex: dose-effect studies in cadmium smelter workers.

Cadmium was measured in vivo in the left kidney and liver of 82 industrially exposed workers and 10 control subjects. The range of Cd values for the industrial group was 0.9-57 mg for the whole kidney and 0.8-120 ppm for the liver, compared to 0.4-11.8 mg and 0.6-7.9 ppm for the control group. Below 40 ppm in the liver, the kidney Cd burden tended to increase with increasing liver concentration. Above 40 ppm, the kidney Cd content decreased as the liver concentration increased. This biphasic relation between Cd in the kidney and the liver for all subjects showed a critical level of approximately 31 mg Cd in the kidney. Estimates of the critical level by beta 2-microglobulin and urinary protein measurements yielded critical values of 31-42 mg Cd for the whole kidney (300-400 microgram/g for the renal cortex).

Cadmium↗
PubMed1981

A comparison of 252Cf and 238Pu, Be neutron sources for partial-body in vivo activation analysis.

A comparison is made of the isotopic neutron sources 252 Cf and 238 Pu, Be for partial-body in vivo neutron activation analysis. Depth distributions of thermal neutron fluences in a water phantom are very similar for the two sources. The peak depth occurs at 5 cm. This value is approximately 2 cm less than the values obtained with uncollimated neutrons produced in broad-beam irradiations. With respect to the fluence-to-dose ratio, the 252 Cf neutrons have an advantage of approximately 1.4 over the 238 Pu, Be source. The use of 252 Cf offers two additional advantages for the investigator. First, it minimizes the on-line fast-neutron damage in Ge(Li) semiconductor detectors. Secondly, it is subject to much less stringent transport regulations that 238 Pu, Be. The latter feature takes on particular importance in view of the increasing usefulness of transportable instruments for in vivo cadmium measurements at the workplace.

Beryllium↗
PubMed1981

Calibration of a 238Pu,Be facility for partial-body measurements of organ cadmium.

An improved instrument is described for the measurement of liver and kidney cadmium by in vivo neutron activation analysis in both occupationally and environmentally exposed persons. Detailed calibrations of the instrument used in a study of 83 male workers at a cadmium production plant are give. The importance of accurate organ localisation by ultrasound is stressed, without which errors of 40 and 25% in individual and group kidney measurements, respectively, can occur. The detection limit (2 SD of the background) is 2.2 mg cadmium in the kidney and 1.5 micrograms g-1 (wet weight) in the liver for a local dose of 4.7 mSv. This instrument therefore combines the advantages of portability with high sensitivity of detection of cadmium.

Cadmium↗
PubMed1981

Comparison of methods of estimating body fat in normal subjects and cancer patients.

Total body fat can be indirectly estimated by the following noninvasive techniques: determination of lean body mass by measurement of body potassium or body water, and determination of density by underwater weighing or by skinfold measurements. The measurement of total body nitrogen by neutron activation provides another technique for estimating lean body mass and hence body fat. The nitrogen measurement can also be combined with the measurement of total body potassium in a two compartment model of the lean body mass from which another estimate of body fat can be derived. All of the above techniques are subject to various errors and are based on a number of assumptions, some of which are incompletely validated. These techniques were applied to a population of normal subjects and to a group of cancer patients. The advantages and disadvantages of each method are discussed in terms of their ability to estimate total body fat.

Adipose Tissue↗
PubMed1980

In vivo measurement of critical level of kidney cadmium: dose effect studies in cadmium smelter workers.

In vivo measurements of kidney and liver cadmium burdens were obtained in 82 industrially exposed workers and ten control subjects. Kidney cadmium levels ranged from 0.9 mg to 57 mg, and liver concentrations ranged from 0.8 ppm to 120 ppm for the industrial group. Comparison values for the control group were 0.4 mg to 11.8 mg for the kidney and 0.6 ppm to 7.9 ppm for the liver. A biphasic relationship between kidney Cd levels and liver Cd levels was observed. The kidney and liver Cd levels showed an increase until approximately a 40 ppm concentration was reached in the liver. Thereafter, the kidney levels decreased as the liver concentration continued to increase. The kidney cadmium level at which this change occurred was approximately 31 mg for the total kidney. Further estimates of the critical level, based on years of exposure and renal dysfunction (beta 2-microglobulin, proteinuria), yielded estimates of 31 mg to 42 mg cadmium (300-400 micrograms/gm for the renal cortex).

Cadmium↗
PubMed1980

Compartmental body composition based on total-body nitrogen, potassium, and calcium.

The techniques of prompt gamma neutron-activation analysis for the measurement of total-body nitrogen and whole-body counting for the measurement of total-body potassium were used to determine the mass of muscle and nonmuscle lean tissue and their protein content in 135 normal male and female subjects, 20-80 yr of age. Age-related changes in the size of the muscle and nonmuscle compartments and their protein content provide basic data for the investigation of protein metabolism in aging subjects and in individuals with various metabolic disorders, particularly wasting diseases such as cancer. Significant age-related changes in the size of various body compartments were noted. The loss of muscle mass and its protein content contrasts with the relative constancy of the nonmuscle lean tissue and suggests that skeletal muscle is particularly vulnerable to the aging process.

Adult↗
PubMed1979

Cadmium: in vivo measurement in smokers and nonsmokers.

Absolute amounts of cadmium (in milligrams) in the left kidney and concentrations of cadmium (micrograms per gram) in the liver were measured in vivo in 20 healthy adult male volunteers. Organ cadmium levels of smokers were significantly elevated above those of nonsmokers. No relationship was evident between body stores of cadmium (liver and kidney) and cadmium or beta 2-microglobulin in urine or blood. The average total body burden of cadmium in man at age 50 is estimated to be 19.3 milligrams for nonsmokers and 35.5 milligrams for smokers (38.7 pack-year smoking history). Biological half-time for the whole body was, on average, 15.7 years (10- to 33-year range). Dietary absorption was 2.7 micrograms per day. Cigarette smoking resulted in the absorption of 1.9 micrograms per pack.

Adult↗
PubMed1979

Nuclear resonant scattering of gamma rays--a new technique for in vivo measurement of body iron stores.

A technique for the measurement of body iron utilising nuclear resonant scattering of gamma rays has been developed. 847 keV photons emitted from a gaseous 56MnCl2 source are resonantly scattered from 56Fe present in the body. Measurement is made using large volume Ge(Li) detectors. The spatial uniformity of activation, the sensitivity of the detection system and the limits of detection have been investigated. Measurements were made on a liver phantom. The resonance scattering technique permits determination of normal levels of Fe in the liver with a radiation dose of 2 rem.

Body Composition↗
PubMed1979

In vivo measurement of body nitrogen by analysis of prompt gammas from neutron capture.

A method for the in vivo determination of body nitrogen by prompt gamma photons from neutron capture is described. An 85-Ci 238Pu-Be source provides the neutrons. The gamma detection system consists of two 15.24 x 15.24 cm Nal(TI) detectors placed above the patient. Absolute value of body nitrogen is determined using body hydrogen as an internal standard. The reproducibility of the method is +/- 3% for a body dose of 26 mrem.

Adult↗
PubMed1977

A facility for in vivo measurement of kidney and liver cadmium by neutron capture prompt gamma ray analysis.

An in vivo method for the determination of Cd levels in human kidney and liver has been developed. The method allows detection of absolute quantities of Cd in the left kidney and Cd concentration in the liver. The limit of detection of cadmium is 2.5 mg for the left kidney and 1.8 microgram/g (wet weight) for the liver, for a localized dose of 670 mrem. The effects of patient positioning, organ geometry and liver-kidney interference on the measurement have been investigated using an Alderson phantom.

Cadmium↗