Isaac Lewin

Changes in metabolism in obese persons during starvation.

Abstract Metabolic balance studies were performed under strictly controlled conditions during a period of starvation. The data were compared to those obtained during a period of full calorie intake prior to starvation and during a period of refeeding with a low-calorie diet in the same patients. The duration of the phase of starvation ranged from twelve to twenty-four days. The marked catabolism and loss of body weight in the phase of starvation was associated with a net loss of large amounts of nitrogen, phosphorus, calcium, potassium, sodium and water. The rate of catabolism tended to diminish during the later stages of starvation. The hypercalciuria in starvation paralleled the degree of decrease in the plasma carbon dioxide combining power. The serum uric acid level increased markedly during starvation. Refeeding with a calorie deficient diet (600 calories) resulted in a prompt phase of anabolism as evidenced by the net gain of nitrogen, phosphorus, calcium, potassium and sodium. There was also retention of water and stabilization of the body weight on the low calorie diet. The serum uric acid promptly returned to normal levels.

Fluoride Metabolism in Man

Fluoride balances were measured in man under strictly controlled dietary conditions before and during the intake of sodium fluoride, and after its discontinuation. Fluoride intake averaged 4.4 mg/day in the control perlod and 13.8 mg during the addition of an average of 21 mg sodium fluoride/day. The main pathway of fluoride excretion was via the kidney. Urinary fluoride excretion corresponded to about 50 per cent of the fluoride intake in the control study and during the intake of sodium fluoride. Fecal fluoride excretion was very low, averaging 0.29 mg/day in the control period and 0.88 mg/day during the sodium fluoride study. Fluoride balances were positive in all study phases and averaged +1.9 mg/day in the control period and +5.4 mg/day during the addition of 9.1 mg fluoride/day given as sodium fluoride. Fluoride retention corresponded to 42.9 per cent of the fluoride intake in the control period and to 39.3 per cent in the sodium fluoride study. Following the discontinuation of sodium fluoride, the fluoride balances were lower than in the control study. The loss of fluoride in sweat was not determined in these balance studies.

Absorption of calcium in osteoporosis

Abstract The metabolic effects of long-term supplementation of calcium to the diet (one and a half to four years) were studied under controlled dietary conditions in three patients with postmenopausal osteoporosis. The calcium balances were slightly negative during periods of low calcium intake. Increasing calcium intake five to ten times by adding calcium gluconate tablets to the diet improved the calcium balances. However, this improvement was considerably less than in young persons and in patients without osteoporosis. Radioisotope and balance studies revealed that the high fecal calcium excretion during high calcium intake was principally due to unabsorbed calcium and not to increased excretion of endogenous fecal calcium. The data suggest that patients with osteoporosis have a decreased ability to absorb added calcium from the intestine as compared to young persons or to patients of comparable age without osteoporosis.

Influence of dietary calcium intake on Ca47 absorption in man

Abstract The absorption of calcium, using Ca 47 as the tracer, was determined in twenty-one patients under controlled dietary conditions during both low and high calcium intake; each patient served as his own control. The absorption of Ca 47 , determined from the fecal Ca 47 excretion and as judged by the Ca 47 plasma levels, varied greatly in different persons on the same constant low calcium intake and also during a period of constant high calcium intake. The Ca 47 absorption differed significantly during low and high calcium intake in the same patients. The average per cent absorption of Ca 47 in the twenty-one patients was 63.6 per cent during low calcium intake and 30.5 per cent during high calcium intake. The Ca 47 plasma curves were similar during low and high calcium intake, the highest level being attained at four hours after the ingestion of the dose under these study conditions. The Ca 47 plasma level in all patients was significantly lower during high than during low calcium intake, the lower Ca 47 plasma levels corresponding to the higher fecal Ca 47 excretion in the high calcium study. The studies emphasize three observations: (1) the importance of calcium intake in estimating calcium absorption from radiocalcium data in man, (2) the great variability in calcium absorption of persons on the same calcium intake (low or high), and (3) the need for stool collections over a period sufficiently long to permit estimations of radiocalcium absorption from fecal radiocalcium excretion.

INHIBITION OF RADIOSTRONTIUM ABSORPTION BY ALUMINUM PHOSPHATE GEL IN MAN AND ITS COMPARATIVE EFFECT ON RADIOCALCIUM ABSORPTION.

Abstract Studies performed under constant and strictly controlled dietary conditions have shown that a single oral dose of aluminum phosphate gel, ranging from 300 ml to 100 ml, given immediately prior to the oral dose of 85Sr decreased the absorption of 85Sr in man by an average of 87·5 per cent. An amount of 100 ml aluminum phosphate gel was as effective as 300 ml in decreasing the absorption of 85Sr. The decrease in 47Ca absorption was considerably less than the decrease in 85Sr absorption, averaging 37·8 per cent. The disproportionate decrease in 47Ca and 85Sr absorption in the aluminum phosphate gel studies resulted in a marked increase in the 47Ca/85Sr discrimination ratio of the absorption and of the plasma levels of these radio-isotopes. A comparison of the absorption of 47Ca and 85Sr determined in the same patients in the aluminum phosphate gel studies showed an average 47Ca/85Sr discrimination ratio of 12·9 as compared to a value of 1·62 in the control studies. The aluminum phosphate gel studies have shown that this non-toxic, well-tolerated substance is effective in inhibiting the absorption of acutely ingested radiostrontium in man and that this compound decreases the absorption of 47Ca to a considerably lesser extent.

INHIBITION OF RADIOSTRONTIUM ABSORPTION IN MAN.

Abstract The ingestion of aluminum phosphate gel with breakfast caused an average 87 per cent decrease of the intestinal absorption of radiostrontium in man as judged by two different criteria: the marked decrease in the Sr85 plasma levels and the increase in the fecal Sr85 excretions after administration of an oral tracer dose.

A metabolic study following extensive resection of the small intestine for sarcoma

Abstract 1.1. A metabolic study in a patient with extensive resection of the small intestine due to recurrent leiomyosarcoma is reported. 2.2. The metabolic data indicate adequate absorption and utilization of nutrients. This is best illustrated by analyzing the calcium balance which improved by increasing the intake. A low urinary calcium excretion irrespective of the calcium intake was noted in the presence of normal serum calcium levels. This is indicative of compensatory efforts of the body to retain calcium. The calcium tolerance test was useful in elucidating this point. 3.3. The fecal content of water, fat, minerals and electrolytes in the stool was increased. These losses may be due to disturbance of reabsorption of intestinal juices and of metabolites re-excreted into the intestinal canal. The fecal electrolyte content approximated the electrolyte concentration of a plasma ultrafiltrate. 4.4. The varying degree of metabolic disturbance following intestinal resection appears to depend upon the intestinal surface available for absorption and reabsorption. 5.5. Derangements of metabolism in cases of malignancy may be ascribed to factors other than impaired intestinal absorption.

Effect of Aluminum Phosphate Gel on Radiostrontium Absorption in Man

The effect of aluminum phosphate gel on the absorption of radioactive strontium was studied in man under constant and controlled dietary conditions on a low calcium intake in 11 of the 13 cases. Studies previously performed in this laboratory have shown that 100 ml of this compound given immediately prior to the oral administration of

Effect of Stable Strontium on Radiostrontium Excretion in Man

{}^{85}{\rm Sr}

Effect of magnesium on radiostrontium excretion in man

decreased the absorption of radiostrontium by an average of 87%. In the present investigation, the effectiveness of aluminum phosphate gel, given 1/2 hour and 1 hour after the ingestion of radiostrontium, was studied on the absorption of this radioisotope in man. The absorption of