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PubMedDate not supplied

[Long-term anticonvulsant therapy and calcium and phosphorus metabolism].

The authors examined 114 epileptic patients who were taking anticonvulsant drugs from different periods of time. Serum and urinary calcium and phosphorus and serum alkaline phosphatase levels have been studied. Roentgenographic researches have been made in order to asses the bone mineral content. Urinary D-glucaric acid excretion as a quantitative index of hepatic enzyme induction has been determined in some subjects. The results show the presence of minor alterations both in calcium and phosphorus metabolism and in bone structure at a subclinical level. These findings suggest the importance of climatic and nutritional factors in the development of bone alterations pointed out by several authors in epileptic patients on long-term anticonvulsant therapy.

Adolescent↗
PubMed1972

Effects of dibutyryl cyclic adenosine 3',5'-monophosphate and parathyroid extract on calcium and phosphorus metabolism in hypoparathyroidism and pseudohypoparathyroidism.

It has been proposed previously that the metabolic defect in pseudohypoparathyroidism which accounts for parathyroid hormone unresponsiveness is an absence or abnormal form of the adenyl cyclase system in kidney and presumably in bone. To determine whether there is an associated defect in the response mechanism to cyclic adenosine 3',5'-monophosphate (cyclic AMP), the effects of parathyroid extract (PTE), and dibutyryl cyclic AMP were compared in patients with either surgical hypoparathyroidism or pseudohypoparathyroidism. PTE and dibutyryl cyclic AMP both increased serum and urinary calcium, lowered the serum phosphorus, and increased urinary phosphorus in patients with hypoparathyroidism. PTE also increased urinary cyclic AMP in these patients. PTE increased serum and urinary calcium and urinary phosphorus but did not alter serum phosphorus or urinary cyclic AMP in the patients with pseudohypoparathyroidism. Dibutyryl cyclic AMP increased the serum and urinary calcium, lowered the serum phosphorus, and increased urinary phosphorus in all the patients with pseudohypoparathyroidism. The results indicate that (a) dibutyryl cyclic AMP can reproduce the effects of parathyroid hormone on calcium and phosphorus metabolism in man, (b) the response mechanism to cyclic AMP appears to be intact in pseudohypoparathyroidism, and (c) PTE apparently produces some of its characteristic effects on calcium and phosphorus metabolism in pseudohypoparathyroidism in the absence of an increase in urinary cyclic AMP.

Adolescent↗
PubMed1975

Calcium and phosphorus metabolism in chronic uremia.

In chronic uremia, the clinical disorders o calcium and phosphorus metabolism are influenced by the following factors: (1) intestinal absorption of calcium and phosphate, resulting in a negative calcium and phosphate balance at normal dietary intakes; (2) renal handling of calcium and phosphate: the fractional transport of calcium (the isoosmotic reabsorption taking place in the proximal tubule) is not affected by GFR modifications, whereas the Tm-limited reabsorption is severely impaired; the external phosphate balance is kept, even in the presence of a reduced nephron population, by means of a proportional reduction in TmPO4 values; (3) physiochemical state and turnover of body calcium and phosphate: in uremic patients, the distribution spaces, turnover rate of calcium, and accretion rate of bones are increased in comparison with the controls; the calcium infusion test in patients with renal osteomalacia is followed by a regular increase in plasma [PO4], whereas a significant decrease is observed in patients with renal osteitis fibrosa, due to the extreme 'avidity' of bones for calcium phosphate; the role of hyperphosphatemia is critical in keeping the plasma [Ca] lower than the expected values for a given metabolic set; moreover, an increased cell uptake of phosphate could counteract to some extent the reduced renal clearance of phosphate; (4) structural and biochemical modifications of bone tissue: uremic osteodystrophy consists mainly of two components: (a) osteomalacia, with osteoid excess, disappearance of the calcification front, and diffuse pathologic mineralization, and (b) osteitis fibrosa, with severe resorption of normally mineralized bone, slight osteoid excess, and almost normal calcification front; (5) hormonal factors: chronic stimulation of parathyroid glands may result in suppressible or even autonomous hyperparathyroidism. As to vitamin D, it has been suggested that the uremic kidney is not able to synthesize the 1,25-di-OH-cholecalciferol, the active metabolite of vitamin D: this results in an impaired intestinal absorption of calcium. On the contrary, the role of calcitonin in chronic uremia is still uncertain, since low values of plasma [Ca] are usually observed.

Calcium↗
PubMed1980

The control of calcium and phosphorus metabolism by the vitamin D endocrine system.

Vitamin D, which is normally produced in the skin under ultraviolet irradiation, is the building block for a new endocrine system that involves hydroxylation on the 25-position in the liver followed by 1 alpha-hydroxylation in the kidney to produce the vitamin D hormone, 1 alpha, 25-(OH)2D3. This vitamin D hormone functions in the intestine, bone, and kidney to stimulate transport of calcium and phosphorus into the extracellular fluid compartment upon demand. The production of the vitamin D hormone is tightly feedback regulated directly or indirectly by calcium and phosphorus levels of the plasma. The vitamin D endocrine system is an important one in the regulation of calcium and phosphorus metabolism but is not solely responsible for the calcium and phosphorus transfer reactions occurring during reproduction. The vitamin D hormone functions in the target organs by a nuclear-mediated receptor-based mechanism probably involving the biogenesis of calcium and phosphorus transfer proteins. New target sites of 1,25-(OH)2D3 action in several tissues are suggested by this nuclear localization in those cells. Study of the vitamin D endocrine system has provided a new understanding of metabolic bone diseases and has provided new forms of vitamin D for their treatment. Thus a basic investigation of the regulation of calcium and phosphorus metabolism has rewarded medicine and science with new therapeutic approaches to disease problems.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2005

[Effects of phosphorus sources of different forms on phosphorus metabolism of Microcystis aeruginosa and adhesive Pseudomonas sp].

The effects of different forms of phosphorus sources on the phosphorus metabolism of Microcystis aeruginosa and attached Pseudomonas sp. were investigated after four substance of different phosphrus forms: NaH2PO4, Natrium-beta-glycerophosphate (NaGly), Ca3(PO4)2 and lecithin were added in the non-phosphorus MA culture. The growth of Microcystis aeruginosa, total phosphorus, alkaline phosphatase activity in water and total phosphorus in Microcystis aeruginosa were measured every day or every two days. Results show that attached Pseudomonas sp. could accelerate the growth of Microcystis aeruginosa, and transform some phosphrus forms which could not be assimilated very easily by Microcystis aeruginosa to some forms as phosphate to utilize for Microcystis aeruginosa. Alkaline phosphatase plays an important role in the utilization of large molecular organic phosphorus by Microcystis aeruginosa and attached Pseudomonas sp.

Alkaline Phosphatase↗
PubMedDate not supplied

Effect of hypothyroidism on phosphorus metabolism in muscle and liver: in vivo P-31 MR spectroscopy study.

Hypothyroidism is known to affect nearly every organ and organ system of the human body. The goal of the present study was to gain insight into the phosphorus metabolism and bioenergetic function of striated (calf) muscle and liver in patients with hypothyroidism before and after thyroid hormone treatment. With an ISIS (image-selected in vivo spectroscopy) magnetic resonance (MR) technique for volume selection, phosphorus-31 metabolism of the calf muscle in 10 patients and of the liver in seven patients with severe hypothyroidism was studied before and after treatment. In addition, spectra from the calf muscle and liver were obtained in 10 healthy volunteers. Relative to those from the healthy subjects, the P-31 MR spectra from patients with hypothyroidism showed a significantly diminished phosphocreatine/inorganic phosphate ratio (P less than .01). After thyroid hormone substitution therapy, this ratio returned to normal values within several weeks. No statistically significant changes in the spectra of liver tissue could be detected. The results support the theory that hypothyroidism induces a hormone-dependent, fully reversible impairment of the energy metabolism of striated muscle. Changes in liver metabolism observed with biochemical methods are apparently not detectable with state-of-the-art P-31 MR spectroscopy.

Adult↗
PubMed1988

Renal aspects of calcium and phosphorus metabolism in preterm infants.

The aim of this study is to emphasize renal aspects of calcium and phosphorus metabolism from our data of more than 200 metabolic balance studies carried out in preterm infants. Renal production of 1,25-dihydroxyvitamin D increased rapidly after birth provided the concentration of the substrate, 25-hydroxyvitamin D, is adequate. The gut of preterm infants is able to respond to the active metabolite of vitamin D. Mean plasma phosphate threshold for tubular reabsorption of phosphate is high, about 2.1 mmol/l or 6.5 mg/dl. The low fractional excretion of phosphate cannot be explained by immature parathyroid function nor by renal unresponsiveness to parathormone, at least after the first days of life. It is probably due to regulating factors related to the high rate of growth. Because of reduced glomerular filtration rate, a too high phosphorus intake may result in hyperphosphatemia. Conversely, a too low phosphorus intake will lead to a phosphate depletion syndrome characterized by marked increase in urinary calcium excretion, no urinary phosphate, and hypophosphatemia. Preterm infants with chronic metabolic acidosis are able to acidify urine so that titratable acid is directly related to urinary excretion of phosphate. Clinical implications are that calcium:phosphorus ratio in milk must be adapted according to net bone and soft tissue retention.

Acidosis↗
PubMed2000

Genetic disorders of calcium and phosphorus metabolism.

The genetic control of calcium, phosphorus, cartilage, and bone metabolism is discussed, and many of the genes involved in this process are described. Mutations in these genes that lead to the clinical disorders associated with hypercalcemia, hypocalcemia, rickets, and osteochondrodystrophies are delineated.

Bone and Bones↗
PubMed1987

Sodium transport and phosphorus metabolism in sodium-loaded yeast: simultaneous observation with sodium-23 and phosphorus-31 NMR spectroscopy in vivo.

Simultaneous 23Na and 31P NMR spectra were obtained from a number of yeast suspensions. Prior to NMR spectroscopy, the yeast cells were Na-loaded: this replaced some of the intracellular K+ with Na+. These cells were also somewhat P-deficient in that they had no polyphosphate species visible in the 31P NMR spectrum. In the NMR experiments, the Na-loaded cells were suspended in media which contained inorganic phosphate, very low Na+, and a shift reagent for the Na+ NMR signal. The media differed as to whether dioxygen, glucose, or K+ was present individually or in combinations and as to whether the medium was buffered or not. The NMR spectra revealed that the cells always lost Na+ and gained phosphorus. However, the nature of the Na+ efflux time course and the P metabolism differed depending on the medium. The Na+ efflux usually proceeded linearly until the amount of Na+ extruded roughly equalled the amount of NH4+ and orthophosphate initially present in the medium (external phosphate was added as NH4H2PO4). Thus, we presume this first phase reflects a Na+ for NH4+ exchange. The Na+ efflux then entered a transition phase, either slowing, ceasing, or transiently reversing, before resuming at about the same value as that of the first phase. We presume that this last phase involves the simultaneous extrusion of intracellular anions as reported in the literature. The phosphorus metabolism was much more varied. In the absence of exogenous glucose, the P taken up accumulated first as intracellular inorganic phosphate; otherwise, it accumulated first in the "sugar phosphate" pool. In most cases, at least some of the P left the sugar phosphate pool and entered the polyphosphate reservoir in the vacuole. However, this never happened until the phase probably representing Na+ for NH4+ exchange was completed, and the P in the polyphosphate pool never remained there permanently but always eventually reverted back to the sugar phosphate pool. These changes are interpreted in terms of hierarchical energy demands on the cells under the different conditions. In particular, the energy for the Na+ for NH4+ exchange takes precedence over that required to produce and store polyphosphate. This conclusion is supported by the fact that when the cells are "forced" to exchange K+, as well as NH4+, for Na+ (by the addition of 5 times as much K+ to the NH4+-containing medium), polyphosphates are never significantly formed, and the initial linear Na+ efflux phase persists possibly 6 times as long.(ABSTRACT TRUNCATED AT 400 WORDS)

Aerobiosis↗
PubMed1966

Phosphorus metabolism of germinating oat seeds.

An investigation has been made of the changes in the major phosphorus containing substances in Avena sativa during the first 8 days of dark germination. The endosperm, roots, and shoots were analyzed separately for acid soluble-P, phytic acid-P, inorganic-P, lipid-P, nucleic acid-P, and protein-P. Phytic acid-P comprised 53% of the total seed phosphate, while the sum of lipid-P, nucleic acid-P and protein-P comprised 27% of the seed phosphate. All these reserve phosphate materials were mobilized and transferred to the developing axis. The phosphate from phytic acid appeared almost entirely as inorganic-P in the roots and shoots. A close stoichiometry existed between the rate of loss of nucleic acid-P from the endosperm and its rate of appearance in the roots and shoots. Thus no net synthesis of nucleic acid occurred during the 8-day period examined. The rate of synthesis of lipid-P in the roots and shoots exceeded its rate of disappearance from the endosperm during the first 4 days of germination. Protein-P increased in the roots and shoots during germination, but at a rate less than its rate of disappearance from the endosperm. The results provide a relatively complete description of the over-all aspects of phosphorus metabolism associated with germination of oats.

Journal Article↗
PubMed1977

[Observation of the changes in the locomotor apparatus and calcium-phosphorus metabolism in kidney transplant patients].

Renal function indices were analyzed as well as those of calcium-phosphorus metabolism and the state of bone skeleton in seven patients with renal transplantation. Consideration is given to a grave complication resulting from a long-term treatment with corticosteroids--aseptic osteonecrosis, found in two of the subjects observed and severe cortisone myopathy in one of the patients.

Adult↗
PubMed1978

Effect of antithyroid treatment on calcium-phosphorus metabolism in hyperthyroidism. I: Chemical quantities in serum and urine.

The effect of antithyroid treatment on the disturbed calcium-phosphorus metabolism in hyperthyroidism was studied in 16 patients. Elevated serum concentrations and urinary excretions of calcium and phosphorus were almost normalized 4 weeks after the start of medical treatment. Serum immunoreactive parathyroid hormone was decreased in the hyperthyroid state and became normal after medical treatment. Serum alkaline phosphatase levels were elevated throughout the study with an increase to a maximum peak after 8 weeks of antithyroid treatment. Urinary hydroxyproline excretion was initially markedly increased and fell rapidly during therapy. The observed changes suggest decreased bone resorption and increased bone formation with deposition of bone mineral after antithyroid treatment. Alterations in the serum albumin concentration during the investigation period influenced the total serum calcium concentration. Using albumin adjusted serum calcium values no hypocalcaemia was found during medical treatment or after a subsequent subtotal thyroidectomy.

Adult↗