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Biomedical subjects

S H Cohn

Publications and source records attributed to S H Cohn.

At least 109 records · Page 6Linked to original sources
PubMed1976

Body composition and skeletal metabolism following pituitary irradiation in acromegaly.

The change in body composition in acromegaly that resulted from pituitary irradiation was examined using the technic of total body neutron activation analysis. Before treatment, increased ratios of total body P:Ca, P:K and Na:K were noted. After pituitary irradiation, the total body levels of P, Na and K were reduced in a proportion that indicated restoration of body composition towards normal. Skeletal mass (total body calcium) decreased into the range observed in osteoporosis in several patients. Trabecular bone mass, as reflected by the Singh Index, was consistently reduced, and two patients had vertebral compression fractures. Local bone mass as determined by photon absorptiometry was reduced when the values were normalized for age, sex and body size. It is postulated that in untreated acromegaly there is differential bone remodelling with an increase in cortical bone accompanied by a reduced trabecular bone mass. When reduction of hGH levels is accomplished with treatment, cortical apposition may decrease. Since the increased cortical bone mass probably aids in preventing vertebral compression fractures, the treated acromegalic patient may incur an increased risk of fractures. This risk may be increased further by the hypogonadism which may arise secondary to pituitary irradiation or surgery. It would be prudent to ensure that the hypogonadal acromegalic patient receives an adequate calcium intake and sex hormone replacement therapy.

Acromegaly↗
PubMed1976

Effect of hydrocortisone on total body calcium in rats.

Administration of 5 mg. of hydrocortisone acetate to rats every other day for 2 weeks resulted in growth retardation and weight loss as indicated by body weights of experimental animals, which averaged 33 per cent lower than those of the controls, and a significant decrease in the length of the tibiae and femurs (p less than 0.01 for treated vs controls). However, despite the smaller size of the treated animals, the values for total body calcium (TBCa) and the calcium in the tibia and femur did not differ significantly from control values. Thus, there was more calcium per unit length of bone, resulting in an increase in the skeletal density of treated rats. This finding was confirmed by x-ray examination of these bones. The net intestinal absorption of calcium (rate of initial entry) calculated from plasma levels following an oral and intravenous dose of 47Ca and 85Sr, respectively, was not significantly different in hydrocortisone-treated rats compared to controls. This would indicate that the rate of intestinal absorption of calcium is unimpaired despite the administration of massive doses and corticosteroids. When the animals were placed on a calcium-deficient diet, both TBCa and tibia and femur calcium levels were decreased. Subsequent administration and hydrocortisone did not alter the calcium values. The results of this study are compatible with the hypothesis that hydrocortisone promotes weight loss, retards growth, but inhibits the rate of bone resorption.

Animals↗
PubMed1975

Absence of an effect of chronic administration of growth hormone on serum lipids.

Human growth hormone (hGH) was administered to a group of osteoporotic patients at two dosage levels for a period of 6 mo each. The first dose employed was 2 units subcutaneously daily, and the second dose was 0.2W-3/4 units (where W is body weight expressed in kg) daily. There was no significant change in serum-cholesterol or triglyceride concentration despite the production of hyperglycemia and soft-tissue swelling on the higher dosage regimen. A number of factors may account for the conflict between our findings and a previous report in which hGH administration had a lypocholesterolemic, hyperglyceridemic effect. These factors include differences in sex, age, dosage, and duration of treatment. Nonetheless, it is clear that from a therapeutic vantage, even if hGH were readily available, it would not be a useful hypocholesterolemic agent.

Aged↗
PubMed1975

Correlation between skeletal calcium mass and muscle mass in man.

The measurements of total body potassium (TBK) and calcium (TBCa) were made on 317 subjects by the techniques of whole-body counting and total-body neutron activation analysis (TBNAA), respectively. The TBK/TBCa ratios are constant for normals over the age range studied. The males have more cellular mass (TBK) per unit skeletal mass (TBCa) than the females, as indicated by their respective TBK/TBCa ratios, 0.122 +/- 0.008 (1 SD), and 0.100 +/- 0.007 (1 SD). In general, patients with various metabolic disorders tend to follow the physiological trend found in the normals. In a number of metabolic disorders, the loss of TBK was usually approximately 60% of that of the TBCa when expressed in terms of the predicted normal values. This suggests that the mechanism causing the loss of calcium in physiological and altered metabolic states simultaneously involves both the skeleton and its associated musculature.

Adult↗
PubMed1975

Phonton absorptiometry and skeletal mass in the treatment of osteoporosis.

Thirty-six osteoporotic patients who underwent several therapeutic regimes were studied on two occasions by photon absorptiometry and total-body neutron activation analysis (TBNAA). These determinations were made at a mean interval of 8.9 plus or minus 0.8 months. The 8-cm radial site was chosen for the photon absorptiometry which was performed with the Norland-Instruments Densitometer. Mean initial bone mineral content (BMC) was 0.724 plus or minus 0.069 gm/cm and mean bone width was 1.235 plus or minus 0.072 cm. The mean percent change in BMC (%deltaBMC) was 1.02 plus or minus 4.2. The initial total-body calcium (TBCa) as determined by TBNAA was reduced when compared with values that would be expected from empirically derived formulas. The mean percent change in TB-Ca (%deltaTB-Ca) was -3.2 plus or minus 4.7. Most patients displayed a change in BMC and TB-Ca that was at least 2 s.d. greater than the precision of the methods used (%deltaTB-Ca greater than 2). No relationship was found between the deltaBMC and the deltaTB-Ca (r = 0.17). These findings suggest that changes in the radical BMC at the 8-cm site cannot be extrapolated to indicate changes in skeletal mass in response to treatment of osteoporosis. Whether photon absorptiometry at other sites or at multiple sites provides a closer relationship to changes in skeletal mass (TB-Ba) remains to be determined.

Activation Analysis↗
PubMed1975

Creatinine excretion and total body potassium in renal failure.

Total body potassium (TB K) and daily urinary creatinine excretion were measured in 12 patients with mild chronic renal disease (CCr/1.73 m2 BSA greater than 40 ml/min, Group I) and 12 patients with severe renal disease (CCr/1.73 m2 BSA less than 19 ml/min, Group II). Creatinine excretion as a function of total body potassium was significantly lower in the males and females of Group II as compared to males and females in Group I. TB K was linearly related to creatinine excretion in both groups of patients. Mean TB K was not significantly different from mean predicted normal values (TB Kp) in both groups. The decreased creatinine excretion observed in severe renal failure cannot be due to a significant loss of lean body mass because TB K was not significantly decreased below predicted normal values. Decreased creatinine biosynthesis, alternate routes of excretion, metabolic reutilization, or conversion of creatinine to other metabolites may have contributed to the decreased creatinine excretion noted in this group of patients with renal failure.

Body Weight↗
PubMed1975

Correlation of radial bone mineral content with total body calcium in chronic renal failure.

Loss of bone mineral of the skeleton in renal disease can be measured directly by total body neutron activation analysis (TBNAA), and also by an absorptiometric technique applied to the appendicular skeleton (radius). In the present study the results of these two techniques are compared in 25 patients with renal insufficiency, 53 patients with end-stage renal failure on dialysis, and 24 normal control subjects. It is apparent that there is good correlation between total body calcium(TBCa) and bone mineral content (BMC) in all groups studied. The correlation in the normal contrast group was 0.944 as compared to 0.919 for the renal patients and 0.892 for patients with end-stage renal failure on dialysis. In order to measure the relative deficit in TBCa in individual patients from the absolute Ca measurement, it is necessary to normalize the data for sex, age, and skeletal size. For this purpose, an empirically derived relationship was used to predict the normal skeletal Ca in each subject, based on weight, height, sex, and age. The measured TBCa divided by the predicted TBCa is referred to as the calcium ratio. This ratio is useful in expressing the relative deficit of Ca in individual renal patients. In similar manner, BMC data were normalized, with the same relationship used to obtain BMC ratios. The normalization procedures allow both the TBCa and BMC measurements to be used to quantitate the Ca deficit in individual patients with renal insufficiency. However, the correlation coefficient relating changes in TBCa and BMC in individual patients on dialysis was very poor (0.25). It is clear that the BMC measurement alone cannot always predict the level of the total body Ca in individual patients with renal failure. In like manner, TBCa measurement alone does not define the distribution of total body Ca between the skeleton and soft tissue in these patients. However, taken together, the BMC measure along with that of TBCa does suggest possible alterations in the skeletal calcium distribution associated with renal disease.

Absorption↗