Oral Calcium Intake Research Articles

A “Carboxyl Terminal” Clinical R Adioim Muno Assay for Parathyroid Hormone with Apparent Recognition Preference for the Intact Hormone

A radioimmunoassay for Parathyroid Hormone which is used in a clinical setting was characterized by immunoreactivity with various synthetic fragments of the hormone, serum parathyroid hormone response to oral calcium intake in normocalcemic calcium stone-formers, and ability to detect fragments of parathyroid hormone secreted by abnormal human parathyroid tissue in vitro. Although almost all of the recognition sites for the antiserum were within the 53-84 carboxyl terminal amino acid sequence of the hormone, the radioimmunoassay mainly detected the "intact" hormone rather than the carboxyl terminal fragment(s) which most "carboxyl-terminal" assays of parathyroid hormone are claimed to preferentially detect. Differences in tertiary structure between the intact hormone and its fragments probably account for the relative inability of this antiserum to detect the carboxyl terminal fragment(s).

Renal Osteodystrophy in Patients Maintained on CAPD for More than Three Years

Studies of renal osteodystrophy in patients maintained on CAPD for short periods have shown conflicting results. The present study reports on the status of renal osteodystrophy in 27 patients maintained on CAPD for over three years. Ten men and 17 women with a mean age of 49.5 years were on CAPD for a mean of 45 months. Dialysate calcium was 6 mg%. Oral dietary calcium intake for all the patients was low (= 500 mg/day). AI(OH)3’ Vit. D and/or 1,25(OH)2D3 were prescribed to maintain serum calcium and phosphorus at normal levels. Patients were divided into two groups according to the radiological findings at the beginning of treatment. Group A (10 patients) included those who had no subperiosteal resorption (SPR) and Group B (17 patients) those with SPR at the initiation of CAPD. In Group A, SPR grade remained normal in eight patients and progressed in two. In Group B, SPR remained unchanged or increased in 14 while it improved in the remaining three.

Rib fractures and anorexia nervosa

A twenty-five year old patient with long standing anorexia nervosa and recent forced vomiting presented with a pulling sensation in her lower anterior thorax. Seven months later, callus formation over the left tenth rib was documented. Chest x-ray revealed healing fractures of the seventh, ninth, and tenth ribs. Since her oral intake of calcium was low, she was started on a regimen of milk and sun bathing. We postulate her rib fractures were the result of forced vomiting in an individual with fragile bones. The osteoporotic state may have been induced by her malnourished low-estrogen state.

Oral daily intake of cadmium, lead, manganese, copper, chromium, mercury, calcium, zinc and arsenic in Belgium: A duplicate meal study

One hundred and twenty four daily meals collected in three areas of Belgium were analysed for their content of several metals. The following median values for 24-hr intakes were found: cadmium, 15 μg; lead, 95.7 μg; manganase, 2.6 mg; copper, 1.3 mg; chromium, 0.24 mg; mercury, 6.5 μg; calcium, 541 mg; zinc, 13.2 mg; arsenic, 11.5 μg. The distributions of the individual results suggest that about 1–2% of the daily meals sampled had mercury and cadmium contents that exceeded the tolerable level proposed by WHO; in the case of lead this level was exceeded in 10%.

An ultrastructural study of postprandial changes in bone lining cells of lead-injected thyroidectomized and thyroid-intact rats.

This report is an electron microscopic study demonstrating intracellular differences in endosteal bone lining cells in tissue removed from thyroid-intact (TI) and thyroidectomized (TX) rats. Rats with functional parathyroid gland transplants, many of which were thyroidectomized, were trained to a 0900 h feeding schedule. Some of the TX rats (TX + CT) were injected postprandially with calcitonin (80 pg/g body weight). One hour before sacrifice all rats were injected with lead acetate (20 mg/kg body weight). Sections of the diaphysealmetaphyseal junction of the tibia were prepared for morphological examination using two procedures designed for the study of nondecalcified bone tissue. The following results were obtained: (a) Following pyroantimonate fixation, the electron-dense precipitate in sections obtained from TI and TX + CT rats was arranged in a distinct intracellular organization within bone lining cells. Following an anhydrous tissue preparation (in ethylene glycol), the mitochondria of these cells contained distinct electron-lucent areas. A similar result was found in tissue from TI rats regardless of the relationship of the time of sacrifice to the last feeding. (b) In TX rats, the major difference in the appearance of these bone lining cells was in tissue removed 4 h following a calcium-containing meal. The electron-dense precipitate (resulting from pyroantimonate fixation) was diffusely distributed throughout the lining cells rather than organized. The mitochondria of the cells (anhydrous procedure) contained distinct electrondense areas. These marked differences in tissues from TX rats were transient. With time following feeding, the histological appearance of these cells returned to that seen in cells from TI rats and TX rats injected postprandially with calcitonin. These results, utilizing the unique reaction of lead with bone cells, demonstrate an additional calcitonin-dependent response of rats to oral intake of calcium. They support the concept that endosteal bone tissue contains target cells for calcitonin and that this hormone has a role in postprandial conservation and storage of calcium.

Hypercalciuria and renal salt wastage: a new congenital syndrome. Successfùll indomethacine (IDM) therapy

A 4 days old boy (gestational age : 36w) presented with renal Na wastage, hypercalciuria and polyuria. The parents were first cousins. It was learned that a 3 years old brother presented a salt +losing syndrome associated with nephrocalcinosis. Plasma renine activity (PRA) and aldosterone (PA) levels were very high (400C ng/1/mn and<2000 pg/ml respectively). The adreno-cortical function was otherwise normal. DOCA had no effect on the Na loss and the Na balance improved only with large NaCl supplements or high doses of fludrocortisone (50-70 μg/Kg/d). The hypercalciuria was permanent reaching values as high as 25 mg/Kg/d and was only slightly reduced by Na restriction, oral phosphorus (P) supplements or low calcium (Ca) intake. Plasma Ca, P, Magnesium (Mg) and parathyroīd hormone levels and urinary Mg and P were normal. Polyuria was constant and water supplements were necessary. There was no other remarkable renal abnormalities. Despite multiple therapeutic trials a severe growth failure (- 4 SD) was present at 11 months. IDM (1.75-2 mg twice a day) was then started : weight and length increased dramatically ; PRA and PA levels, calciuria, diuresis, and water needs became normal within 3 weeks and remained normal three months late. We believe that this infant presents a disorder of the common transport mechanism of Na and Ca at the level of the proximal tubule and the ascending limb of the loop of Henle. Since IDM is known to inhibit renal prostaglandins synthesis, an excessive renal production of these compounds might be responsible for this tubular defect.

NEONATAL HYPOCALCEMIA IN LOW BIRTH WEIGHT INFANTS

During an 8-month period, 37 of 124 infants (29.8%) admitted to a low birth weight (LBW) nursery developed hypocalcemia at a mean age of 29 hours. Ten factors were associated with hypocalcemia, three of which appear particularly relevant: (1) low gestational age (32 weeks or less) with appropriate birth weight, (2) low oral calcium intake, (3) correction of acidosis with NaHCO3. Biochemical determinations showed that, in hypocalcemic infants, there were: (1) lower serum total calcium values at 8 hours of life, prior to the actual development of hypocalcemia at 29 hours; (2) elevated serum phosphorus values; (3) acidotic values in the first hours of life, corrected to normal values at the time of hypocalcemia, and (4) lower serum protein values at 8 hours of life. Three signs were significantly related to hypocalcemia, namely, twitching of one or more extremities, high-pitched cry, and hypotonia.

Calcium Studies in Partially Gastrectomized Patients, with Special Reference to the Oral Intake of Calcium

Calcium Studies in Partially Gastrectomized Patients, with Special Reference to the Oral Intake of Calcium

EFFECT OF DOUBLING THE ORAL INTAKE OF CALCIUM ON THE UPTAKE OF RADIOACTIVE STRONTIUM IN RATS.

SummaryRats of two age-groups fed from weaning on a diet of constant composition were given a constant daily dose of 45Ca and 85Sr incorporated in the diet. In young rats (5 to 19 weeks old) increase of the calcium-intake from 0·56 to 1·1 g per cent decreased the skeletal retention of radioactive strontium by 45 per cent. In adults (16 to 26 weeks old) there was no change in the radioactive strontium deposited in bone when the calcium intake was doubled. The renal clearance of 85Sr increased with age and was also higher in rats on the higher calcium-intake.The overall discrimination between strontium and calcium, diet to bone, was not only age dependent but also showed a marked change when the calcium-intake was doubled.