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At least 91 records · Page 5Linked to original sources
PubMed1978

Adaptations in the calcium and phosphorus metabolism of sheep in response to an intravenous infusion of Ca.

1. The effect on calcium and phosphorus metabolism of a high rate of Ca infused directly into the blood of Ca -deficient wethers, already receiving an adequate Ca intake, has been studied by a combination of balance and radioisotope techniques. 2. The rate of Ca retention, which was already high, increased only slightly during the infusion before it reached a maximum. The surplus Ca was compensated for by a decrease in the rate of absorption and an increase in the rate of urinary Ca excretion. 3. These findings support the theory that at maximum retention the rate of Ca absorption becomes regulated according to the rate at which Ca can be stored in bone. 4. results suggest that the decreased absorption was due to a decrease in the rate of active absorption and that the low rate remaining was due to diffusion. 5. The rate of P retention was increased by the Ca infusion, possibly as a result of the increased Ca retention.

Adaptation, Physiological↗
PubMed1993

Disorders of calcium and phosphorus metabolism in adolescents.

During adolescence, there are marked changes in the metabolism of calcium and phosphorus and a dramatic increase in the rate of bone mineralization under the influence of the sex hormones, growth hormone, and insulin-like growth factor-1. More than 50% of adult bone mass is accumulated during puberty; failure to achieve maximum bone mineralization at this time may lead to osteopenia and its complications in later adulthood. This article discusses the causes, evaluation, and management of adolescents with hypocalcemia, hypercalcemia, and disorders of bone mineralization.

Adolescent↗
PubMed1975

Effects of 1alpha-hydroxy-vitamin D3 and 1,25-dihydroxy-vitamin D3 on calcium and phosphorus metabolism in hypoparathyroidism.

The effects of 1alpha-OH D3 or 1,25-(OH)2D3 on calcium and phosphorus metabolism have been evaluated in five hypoparathyroid patients to establish the direct effects of these compounds in adult humans, uncomplicated by compensatory changes in parathyroid hormone secretion. Doses of 1-2.5 mug/day in four patients (5 mug/day in a fifth patient on diphenylhydantoin and phenobarbital) caused a marked increase in serum calcium concentration and urinary calcium excretion, without significant changes in renal calcium clearance or urinary hydroxyproline excretion. These results suggest that the correction of hypocalcemia involved primarily a stimulation of intestinal calcium absorption rather than a stimulation of skeletal calcium resorption. Simultaneously, there were increases in urinary phosphorus excretion and variable changes in serum inorganic phosphate concentration. These effects were produced by doses of 1alpha-OH D3 and 1,25-(OH)2D3 which approach the dose needed to prevent rickets, in contrast to the very large doses of vitamin D or 25-OH D3 required for comparable effects in hypoparathyroid patients. The increased relative effectiveness of these one-hydroxylated forms of vitamin D reveals a deficiency of vitamin D one-hydroxylation in hypoparathyroidism. The rapidity of action of 1alpha-OH D3 and 1,25-(OH)2D3 was also striking. Apart from its physiologic implications, the potency of the one-hydroxylated forms of vitamin D offers significant therapeutic advantages in some patients whose hypoparathyroidism is difficult to control with vitamin D itself.

Adult↗
PubMed1979

Calcium, magnesium, and phosphorus metabolism, and parathyroid-calcitonin function during prolonged exposure to elevated CO2 concentrations on submarines.

Studies of calcium and phosphorus metabolism and acid-base balance were carried out on three Fleet Ballistic Missile (FBM) submarines during prolonged exposure to elevated concentrations of CO2. The average CO2 concentration in the submarine atmosphere during patrols ranged from 0.85% to 1% CO2. In the three studies, in which 9--15 subjects participated, the urinary excretion of calcium and phosphate fell during the first three weeks to a level commensurate with a decrease in plasma calcium and increase in phosphorus. In the fourth week of one patrol, a marked increase was found in urinary calcium excretion, associated with a rise in blood PCO2 and bicarbonate. Urinary calcium excretion decreased again during the 5th to 8th week, with a secondary decrease in blood pH and plasma calcium. During the third patrol, the time course of acid-base changes corresponded well with that found during the second patrol. There was a trend toward an increase in plasma calcium between the fourth and fifth week commensurate with the transient rise in pH and bicarbonate. Plasma parathyroid and calcitonin hormone activities were measured in two patrols and no significant changes were found. Hydroxyproline excretion decreased in the three-week study and remained unchanged in the second patrol, which lasted 57 days. It is suggested that during prolonged exposure to low levels of CO2 (up to 1% CO2), calcium metabolism is controlled by the uptake and release of CO2 in the bones. The resulting phases in bone buffering, rather than renal regulation, determine acid-base balance.

Acid-Base Equilibrium↗
PubMed1989

Effect of dietary aluminum on calcium and phosphorus metabolism and performance of laying hens.

The effect was studied of feeding dietary Al as aluminum sulfate on calcium and phosphorus metabolism and performance of Single Comb White Leghorn laying hens. In Trial 1, graded levels of Al (0, .05, .10, or .15%) were added to a corn-soybean meal layer diet containing 3.3% Ca and .5% available P. Each diet was fed for 28 days to six groups of six individually caged hens. Adding .15% Al to the diet significantly (P less than .05) reduced feed intake, egg production, body weight, tibia breaking strength, and plasma inorganic P. In Trial 2, graded levels of Al (0, .1, .2, or .3%) were added to the basal diet. Each diet was fed to five or six individually caged hens for 42 days. Feeding .3% Al significantly (P less than .05) decreased plasma inorganic P in samples collected immediately following oviposition after 10 and 42 days of treatment. Plasma total Ca, tibia weight, and tibia breaking strength were unaffected by dietary treatments. Egg production and feed intake during Days 1 through 21, but not during Days 22 through 42, were significantly reduced by .3% Al. The results indicated that the addition of .3% Al to a laying hen diet has a negative effect on P metabolism and egg production.

Aluminum↗
PubMed1978

The effect of 1-alpha-hydroxycholecalciferol on calcium and phosphorus metabolism in the lactating ewe.

1. The effect of 1-alpha-hydroxycholecalciferol (1 alpha-OH-D3) on calcium and phosphorus metabolism has been studied in ewes at peak lactation by a combination of a mineral balance and a radioisotope technique. 2. The rate of Ca absorption was substantially higher in the treated ewes than in controls. The rates of endogenous loss of Ca into urine, faces and milk, however, were only slightly higher. 3. In consequence, the net retention of Ca was increased and the loss of skeletal reserves of Ca normally associated with peak lactation, prevented. 4. Although the rate of bone accretion increased slightly, the increase in skeletal retention of Ca resulted mainly from a decrease in the rate of bone resorption. 5. This finding conflicts with the generally held belief that bone resorption is increased by cholecalciferol treatment. 6. The rates of apparent absorption and retention of P were increased by the treatment probably as a result of a direct effect of the 1 alpha-OH-D3 on P absorption. 7. These results provide a possible explanationof the beneficial effect of 1 alpha-OH-D3 in preventing parturient paresis (milk fever) in the dairy cow.

Animals↗
PubMed1993

Effect of dietary aluminum and vitamin D interaction on growth and calcium and phosphorus metabolism of broiler chicks.

The interaction of dietary aluminum (as aluminum sulfate) and vitamin D on growth performance and calcium and phosphorus metabolism was investigated using male broiler chicks. A corn-soybean broiler starter diet, containing .88% Ca and .45% available P and without added cholecalciferol (vitamin D3), was fed with 0 or .2% Al and with 0, 100, or 200 ICU of vitamin D3/kg of diet in a complete factorial arrangement. Four replicate cages of 10 chicks, 1 day of age, were assigned to each dietary treatment. Average body weight gain (328 versus 545 g), feed intake (611 versus 784 g), gain:feed (.54 versus .68), and plasma inorganic P (4.2 versus 6.7 mg/dL) were significantly reduced (P < .05) in chicks fed diets with .2% Al, compared with those fed 0% Al. These four variables were improved by increasing the level of vitamin D3 in the diet from 0 to 100 ICU/kg. However, further improvements were not obtained by elevating the vitamin D3 level to 200 ICU/kg. There were significant interactions of Al and vitamin D3 on gain, feed intake, and gain:feed, but not on plasma P. Gain and feed intake were significantly decreased by Al at each level of vitamin D3. Plasma total Ca was significantly increased by vitamin D3, but was unaffected by Al. Increasing the level of dietary vitamin D3 did not completely alleviate the negative effects of Al.

Aluminum↗
PubMedDate not supplied

[Use of isofocusing for isolating and characterizing phosphorus metabolism enzymes].

A modified procedure is described for colorimetric estimation of phosphate in a sample containing ampholines; the procedure enabled to simplify the detection of some enzymes of phosphorus metabolism in the fractions obtained after isoelectric focusing of the initial protein mixture. The analyses did nor require an isotope technique and dialysis and were carried out within a relatively short period.

Ampholyte Mixtures↗
PubMed1981

[Disturbances of the calcium-phosphorus metabolism and skeletal diseases following kidney transplantation].

53 patients were followed up for an average of 3 years after renal transplantation for evaluation of disturbances in calcium-phosphorus metabolism and skeletal diseases. Postoperative hypercalcemia and hypophosphatemia can be related to persistence of hyperparathyroidism when kidney function is restored. Hypercalcemia was observed in 43% of the patients and lasted less than one year in 80% of cases. Transient hypophosphatemia was present in 15%. These abnormalities did not cause clinical symptoms or deterioration of renal function. However, the skeletal diseases are more impressive and in the first place osteopenia. Bone densitometry revealed decreased bone mineral content in two thirds of the females and one fifth of the males. In females the bone density decreased 3.3% during an average observation period of 7 months, but remained constant in males. Renal osteodystrophy is the main cause of the initial osteopenia. The absence of remineralization or the progression of bone losses is related to the initial persistence of hyperparathyroidism and to corticosteroid treatment. According, 12.5% of the patients presented pathological fractures (spine, hip). In 3 patients (5.7%) with reduced transplant function, osteomalacia without hypophosphatemia was observed. 4 patients (7.5%) had osteonecrosis of the femoral head. There was little progression and surgery was not necessary.

Adult↗