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Biomedical subjects

S H Cohn

Publications and source records attributed to S H Cohn.

At least 19 recordsLinked to original sources
PubMed1991

Relationship of menopause to skeletal and muscle mass.

Cross-sectional and longitudinal changes in body composition with age were examined in white women to determine the relationship of body cell mass to menopause and of body fat to bone mass. There was statistical evidence for a curvilinear component to loss of total body potassium with negligible rates of loss before menopause. Longitudinal measurements also indicated a relationship between the proximity to menopause and the rate of loss of potassium. Total body potassium was significantly related to total body calcium and bone density of the spine, radius, and femoral neck. Total body fat was not related to any of these measurements. We found no evidence that adiposity plays a major role in protecting against bone loss.

Adipose Tissue↗
PubMed1990

Aging bone loss from the femur, spine, radius, and total skeleton.

In order to establish a comprehensive model for involutional bone loss, the following measurements were made of healthy white women: total body calcium by neutron activation analysis, bone density of the distal radius by single-photon absorptiometry, and dual-photon absorptiometry of the lumbar spine and femur (neck, Ward's triangle, and intertrochanteric areas). Longitudinal measurements were made for each of these skeletal sites except the femur. Evidence for a curvilinear component to the pattern of bone loss with aging was found for total body calcium and bone density of the radius, but not for the other measurements on analysis of cross-sectional data. Longitudinal studies confirmed that substantial bone loss begins only after menopause for the radius, whereas there is substantial premenopausal loss of bone from the lumbar spine. Prevention of vertebral osteoporosis requires maximizing bone mass before menopause. If longitudinal data confirm the model of linear rates of bone loss for the femur, there will be important implications for prevention of hip fractures.

Adult↗
PubMed1988

Calcitriol in the treatment of postmenopausal osteoporosis.

Calcitriol was compared with placebo in the treatment of postmenopausal osteoporosis in a double-blind, randomized, parallel clinical trial of 24 months' duration. Adjustment was made in dietary calcium to maximize the dose of calcitriol. The study was completed by 15 patients who received placebo and 12 patients who received calcitriol. The calcitriol group had positive slopes (compared with negative slopes for the placebo group) for total body calcium, bone mineral content of the radius, bone mineral density of the lumbar spine, and radiographic absorptiometry of the middle phalanges. The difference between the two groups was statistically significant for each of these measurements. The fracture rate in the treatment group was 250 per 1,000 patient-years as compared with 333 for the placebo group. The mean dose of calcitriol was 0.8 micrograms per day. Hypercalcemia, hypercalciuria, and perhaps nephrolithiasis were observed as complications of treatment. Calcitriol increased bone mineral density by decreasing bone resorption, but not by increasing bone formation. Future studies should concentrate on treatment with oral calcitriol in lower doses. It would also be of interest to examine parenteral administration of calcitriol. It is possible that bone formation can be increased by achieving higher serum levels of the drug, whereas complications may be avoided by using a non-oral route of administration.

Aged↗
PubMed1988

Premenopausal bone mass is related to physical activity.

The relationship between physical activity and bone mass was investigated in 24 healthy, white, premenopausal women (mean age [+/- SE], 39.0 +/- 1.39 years). Physical activity was determined by a sensor that measures movement of the trunk, and bone mineral levels were determined by means of single- and dual-photon absorptiometry and neutron activation analysis. Total physical activity levels were related both to bone mineral density of the spine (r = .41) and to total body calcium levels (r = .51). There was no significant relationship between the bone density of the distal portion of the radius and activity (r = .20). Nonparametric analysis and stepwise multiple regression analysis revealed negative correlations between cigarette smoking and bone density of the spine and radius. These data suggest that the level of physical activity in sedentary white women may be a determinant of peak total skeletal mass and bone density of the spine.

Adult↗
PubMed1987

Coherence treatment of postmenopausal osteoporosis with growth hormone and calcitonin.

Fourteen women with postmenopausal osteoporosis, all having at least one vertebral crush fracture, were randomly assigned to two treatment arms, each lasting 24 months. The coherence treatment group (7 patients) was treated in the following sequence: human growth hormone (hGH) 7 IU subcutaneously daily for 2 months, followed by 3 months of salmon calcitonin (CT), 100 MRC units every other day. After a 3 month rest period, this sequence was repeated twice. The contrast group (7 patients) was treated intermittently with salmon CT given in the same time periods and at the same dose as in the coherence treatment group. Bone mass was measured every 4 months by neutron activation analysis for total body calcium (TBCa) and by single photon absorptiometry for bone mineral content (BMC) of the distal radius. Although there were no significant differences between the two groups (two-way ANOVA), the rate of change in TBCa in the coherence treatment group was significantly different from zero (F = 3.8, P less than .05) and was +2.3%/year. The increase in bone mass appeared to be sustained throughout the 2 year study, in contrast with previous studies where a plateau effect was observed with calcitonin given alone or continuously with growth hormone. No significant change was found in bone histomorphometric values measured before and after treatment in 4 patients from each group.

Aged↗
PubMed1987

Serum osteocalcin and total body calcium in normal pre- and postmenopausal women and postmenopausal osteoporotic patients.

Serum osteocalcin was measured in 51 normal pre- and 114 postmenopausal women and in 41 postmenopausal osteoporotic patients. Total body calcium (TBCa) was determined in the same individuals by neutron activation analysis. Many of the perimenopausal nonosteoporotic women had increased serum osteocalcin values, but 15 yr or more after the menopause most of the women had serum osteocalcin levels in the normal range. Comparing normal women before and after menopause, the mean serum osteocalcin levels [7.8 +/- 4.7 (+/- SE) and 10.1 +/- 9.4 ng/mL] were not significantly different; however, the TBCa values (898 +/- 99 and 806 +/- 111 g) were significantly different (P less than 0.001). When the normal postmenopausal women were regrouped according to high vs. low osteocalcin values, TBCa and phosphorus content as well as forearm linear bone density were significantly lower in the high osteocalcin group, even though most of the other variables, including urinary hydroxyproline excretion, serum alkaline phosphatase, age, height, and weight, were not different. Osteoporotic women had a mean serum osteocalcin concentration of 17.4 +/- 8.6 ng/ml and a TBCa of 657 +/- 83 g, both significantly different from the respective values in normal and pre- and postmenopausal women (P less than 0.001 for both variables in comparison to each group). These data suggest that high serum osteocalcin levels, at least on a group basis, are an index of low skeletal mass.

Body Constitution↗
PubMed1987

Serial measurements of body composition and total body mineral content in dialysis and nondialysis patients with renal failure.

Thirty-two patients with chronic renal failure, and 68 patients on maintenance hemodialysis underwent serial total body neutron activation over periods of time ranging from 23 to 159 months. Measurements of total body potassium (TBK), total body sodium (TBNa), total body calcium (TBCa), total body phosphorus (TBPhos), and total body chloride (TBC1) were performed. The results were normalized by lean body mass (LBM) or kilogram body weight (BW). The TBNa/LBM and TBC1/BW decreased during the first 36 months of measurements in the dialysis males, while there was no change in the nondialysis males. The TBNa/LBM, TBC1/LBM and TBC1/BW decreased during the first 36 months of monitoring the dialysis females, while a decrease in the LBM was the only change in the nondialysis females. In patients with an increasing K ratio (observed/predicted TBK), the TBNa/LBM and TBCa/LBM decreased and the LBM/BW increased. Similarly, in patients with an increasing Ca ratio (observed/predicted TBCa), the TBCa/LBM and TBPhos increased. The increasing K ratio in dialysis patients with a decreasing TBNa/LBM probably represents an improvement in nutritional status. The increasing TBPhos in dialysis patients with an increasing Ca ratio may represent an increase in skeletal tissue and/or soft tissue calcification. In dialysis females, the total body nitrogen is not different from controls. The total body fat, as a percentage of body weight, is greater in dialysis patients than in controls.

Adolescent↗
PubMed1986

In vivo bone lead measurements: a rapid monitoring method for cumulative lead exposure.

Lead concentrations (microgram/g wet weight) in human bone (tibia) were measured noninvasively in vivo employing an X-ray fluorescence technique. Forty-five workers who had been subjected to chronic industrial exposure were found to have a mean bone lead content of 52.9 micrograms/g wet weight (0 to 198 micrograms/g). In addition to bone lead content, blood lead, body burden of lead as assessed by urinary lead excretion after EDTA chelation, zinc protoporphyrin, and unstimulated urinary lead excretion were evaluated. The results suggest that the in vivo measurement of tibia lead content may serve as an acceptable indicator of body lead burden and provide a practical technique for lead screening purposes. The correlation coefficient between X-ray fluorescence findings and lead excretion following Ca-EDTA administration is 0.69; p less than 0.001.

Bone and Bones↗
PubMed1986

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

With 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/square root H ratios can be classified as at risk for osteoporosis prior to their developing spinal compression fractures. With receiver operating characteristic (ROC) analysis, it was possible to verify the accuracy of the MLR model to discriminate "normal" women at risk, with high sensitivity and specificity. With the MLR model, discrimination of osteoporotic women (50-59 years) was made correctly for 86.2% of the total osteoporotic subjects with the TBCa data. Similar models were derived from the photon absorptiometry data. From the spinal density (BDs) data, correct classification in the 50-59 year group was 55.6% of the total osteoporosis subjects; from the radius density (BMCr) data, the corresponding value was 31%. The highest probability of identifying osteoporosis in all age categories was, therefore, on the basis of TBCa data. Similar, but less accurate discrimination was achieved with the BDs and BMCr data. These conclusions were confirmed by the application of receiver operating characteristic (ROC) analysis. Correct identification of the population at risk permits the timely and efficient application of therapeutic programs prior to onset of fracture. In a serial study of 104 peri-menopausal women, for example, it was possible to determine the P value for individuals measured annually over a 3-10 year period and thus to predict normal individuals at risk for developing osteoporosis each year.

Age Factors↗
PubMed1985

Risk factors for postmenopausal osteoporosis.

Fifty-eight women with postmenopausal osteoporosis (crush fracture of the spine) were compared with 58 age-matched normal women. The osteoporotic women had lower total-body calcium levels and bone mineral content of the radius, had undergone an earlier menopause, smoked cigarettes more, and had breast-fed less often. They also had lower levels of estrone, estradiol, and testosterone and reduced levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D. These findings suggest the presence of changeable risk factors for the development of osteoporosis. Smoking should be discouraged. An adequate intake of calcium and vitamin D should be ensured. It is the opinion of the authors that those women who have had an early menopause or who have a low bone mass at the time of menopause should be given the choice of medically supervised replacement therapy with estrogen and progesterone.

Bone and Bones↗
PubMed1985

Treatment of osteoporosis with calcitonin, with and without growth hormone.

A 24 month randomized parallel study of the treatment of postmenopausal osteoporosis with calcitonin alone v calcitonin alternating with growth hormone (combined treatment) was conducted. Each group received 1000 mg daily of oral calcium supplements. The rate of change in total body calcium for the combined and calcitonin groups was + 1.68%/yr and + 1.33/yr, respectively (P less than .05). However, the difference in the two groups was not statistically significant. Further, the total body calcium level did not increase after 12 to 18 months of treatment. There was significant difference in the rates of change of bone mineral content (BMC) of the radius for the two groups, with a loss of BMC in the combined treatment group (F = 4.80, P less than .05). Calcitonin treatment is effective in producing an increment in bone mass. The addition of growth hormone to this regimen appears to have a deleterious effect on cortical bone mass.

Aged↗
PubMed1985

Cadmium inhalation exposure estimates: their significance with respect to kidney and liver cadmium burden.

Cadmium exposure histories based on employment records, area monitoring techniques, and personal sampling data were obtained for 82 industrially exposed workers. From these data, a time-weighted cumulative exposure index (TWE) was calculated for each worker by multiplying the length of time (ti) in a given work area by the estimated exposure conditions for that area and year (Ei) and then summing these values for the total exposure history TWE = sigma iEiti The cadmium body burden for each worker was measured directly by the in vivo prompt-gamma neutron activation technique. The cadmium content of the left kidney and the liver were measured. For the actively employed workers, a significant correlation (r = 0.70, p less than 0.001) was observed between the exposure index (TWE) and the liver cadmium burden. Furthermore, whenever the worker's liver burden exceeded 40 ppm and the exposure index exceeded 400-500 micrograms/m3 X yr, there was evidence of renal abnormalities (usually elevated urinary beta 2-microglobulin). The highest correlation (r = 0.83, p less than 0.001) was obtained between the kidney cadmium burden data and the exposure index for the active workers without evidence of kidney dysfunction. The percentage of workers with renal abnormalities was found to increase as the exposure index increased. When this relationship was examined using linear logistic regression analysis, the following model was indicated: logit p = 1.24 In TWE--8.34 where p is the individual worker's probability of being classified as having renal dysfunction.

Adult↗
PubMed1985

A proposed method for in vivo determination of lithium in human brain.

A method for measuring Li in vivo in human brain is presented. The technique is based on the measurement of tritium gas exhaled by the subject following neutron irradiation of the organ of interest. The gas collection facility used to separate minute amounts of tritium from the breath is described. Methods for reducing the background levels of tritium were investigated. The limit of detection of the system is estimated to be 350 micrograms of Li for the whole brain for a dose of 10 mSv. This detection limit is sufficient for the study of patients treated with lithium compounds, but is too high to study 'normal' brain lithium content. The rate of elimination of tritium gas from the body was also investigated in animal studies. The method also appears suitable for the measurement of lithium levels in the kidney.

Air↗
PubMed1985

Assessment of cellular mass and lean body mass by noninvasive nuclear techniques.

With the nuclear techniques employed in this study, it has been possible to measure total body potassium (TBK), lean body mass (LBM), and body cell mass (BCM). The latter two are derived independently of TBK. LBM is derived from the sum of total body water (TBW), total body protein, and bone mineral ash measurements. The BCM value is, in turn, based on the difference between the LBM (as measured above) and the sum of the extracellular water and extracellular solids. It was demonstrated in 123 normal individuals that, although the TBK/LBM ratio decreases with age, the TBK/BCM ratio does not change significantly with age. It can be deduced that the ratio of TBK to intracellular water should be relatively constant with age. This relative constancy with age was demonstrated independently with the absolute measurements of TBK and intracellular water in normal individuals. Because the BCM is physiologically and chemically more homogeneous than LBM and because it reflects the actively metabolizing cellular compartment more accurately than LBM, it is the preferred parameter to be used for reference or normalization in body composition studies. For most applications, BCM is readily derived from TBK measurement by either whole body counting or isotope dilution techniques.

Adult↗