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At least 847 records · Page 47Linked to original sources
PubMed1992

Hyperphosphatemia: its consequences and treatment in patients with chronic renal disease.

Control of phosphorus accumulation in chronic renal insufficiency is crucial to the prevention of secondary hyperparathyroidism and metastatic calcification. In early renal failure, calcitriol levels are normal and parathyroid hormone levels are elevated. The phosphorus levels are maintained in the normal range by the phosphaturia induced by hyperparathyroidism. In this situation, dietary phosphorus restriction increases calcitriol levels and suppresses parathyroid hormone secretion. As renal failure progresses into late stages, hyperphosphatemia is evident along with low levels of calcitriol and worsening hyperparathyroidism. Phosphorus restriction will not affect calcitriol concentrations, yet parathyroid levels may decline. During long-term dialysis, urinary excretion of phosphorus is usually minimal. Therefore, phosphorus balance is determined primarily by the net amount absorbed by the bowel and the quantity removed during dialytic therapy. Given an adequate diet, no form of conventional dialysis is able to fully compensate for the gastrointestinal absorption of phosphorus. Hence, compounds that bind phosphorus in the bowel are often necessary. With the realization that the use of phosphorus binders containing aluminum leads to aluminum accumulation and its sequelae: osteomalacia, dementia, myopathy, and anemia, other phosphorus binders have been evaluated. Calcium carbonate has been investigated the most thoroughly and is in wide use. It is inexpensive and contains a high percent of elemental calcium. However, it is only modestly potent in the binding of phosphorus, and large doses are often necessary to attain satisfactory control of phosphorus. This may lead to hypercalcemia. One approach to this problem is to decrease the concentration of calcium in the dialysate. Alternatively, a more effective phosphorus binder may be used. Calcium acetate has been shown in acute studies to have twice the binding capacity of phosphorus per calcium absorbed than calcium carbonate. Whether use of this compound decreases the incidence of hypercalcemia is unproven. Calcium citrate increases the gastrointestinal absorption of aluminum and offers no advantage over calcium carbonate. Other compounds, such as calcium ketoacids and calcium alginate, have not been extensively studied and are not generally available. The use of phosphorus binders containing magnesium in conjunction with a dialysate low in magnesium may be efficacious. Large doses of magnesium will cause diarrhea and thus limit its use as a single agent. Reasons for failure to control hyperphosphatemia include poor compliance, improper prescription of binders, poor dissolution rates seen with some generic brands of calcium carbonate, and the presence of severe hyperparathyroidism. Optimal control of serum phosphorus in dialysis patients should always be viewed in the context of adequate nutrition and protein intake.

Aluminum↗
PubMedDate not supplied

The biological importance of organophosphorus compounds containing a carbon-phosphorus bond.

Organophosphorus anticholinesterase compounds may be derivatives of phosphoric acid or of a phosphonic acid. The phosphonic acid derivatives are usually more reactive and more toxic than the phosphoric acid derivatives. Examples are given to show that differences in the chemical and biological reactivity of phosphates and phosphonates reflect many different aspects of their chemical structure. Some recently discovered naturally-occurring phosphonates are described, together with some synthetic phosphonate analogues of naturally-occurring phosphates. The utility of these synthetic phosphonates as tools for probing enzymic reaction sequences is discussed.

Animals↗
PubMed1989

Phosphorus-31 and Nitrogen- 14 NMR Studies of the Uptake of Phosphorus and Nitrogen Compounds in the Marine Macroalgae Ulva lactuca.

Cytoplasmic phosphomonoesters and inorganic phosphate, as well as vacuolar inorganic phosphate and polyphosphates, gave rise to the major peaks in (31)P nuclear magnetic resonance (NMR) spectra of the marine macroalgae Enteromorpha sp., Ceramium sp., and Ulva lactuca which were collected from the sea. In contrast, NMR-visible polyphosphates were lacking in Pylaiella sp. and intracellular vacuolar phosphate seemed to act as the main phosphorus store in this organism. In laboratory experiments, polyphosphates decreased in growing U. lactuca which was cultivated in continuous light under phosphate-deficient conditions. In contrast, the same organism cultivated in seawater with added phosphate and ammonium, accumulated phosphate mainly in the form of polyphosphates. When nitrate was provided as the only nitrogen source, accumulation of polyphosphates in the algae decreased with increasing external nitrate concentration. From the chemical shift of the cytoplasmic Pi peak, the cytoplasmic pH of superfused preparations of Ulva was estimated at 7.2. The vacuolar pH, determined from the chemical shifts of the vacuolar Pi and the terminal polyphosphate peaks, was between 5.5 and 6.0. The intracellular nitrate and ammonium levels in U. lactuca were determined by (14)N NMR. Both nitrogen sources were taken up and stored intracellularly; however, the uptake of ammonium was much faster than that of nitrate.

Journal Article↗
PubMedDate not supplied

[Modifying effect of nutrition on the mutagenic activity of phosphorus and fluorine compounds].

The test animals were fed with low-grade food during 2-5 months under conditions of acute and chronic action of hydrogen phosphide and hydrogen fluoride induced by inhalation, that resulted in the pronounced impairment of the chromosomal apparatus of the bone marrow cells in the rats. A principal possibility has been established of modification of the hydrogen phosphide and hydrogen fluoride cytogenetic effect by the alimentary action. In particular, it has been found that the effect is significantly higher when the rats are fed with a low-grade ration than under conditions of balanced nutrition.

Animals↗
PubMed2002

Synthesis and structural peculiarities of homeomorphic phosphorus bridgehead macrobicyclic compounds and novel dioxaphospha[3.1.1.]p,m,p-cyclophanes.

The double-capping reaction of p,m,p-trinuclear diphenol 4 with PCl3 affords the three homeomorphic isomers 5-7 of a phosphite macrobicyclic compound in low yields. X-ray structures of out, out-isomer 5 and in, in-isomer 6 show very flat macrobicyclic structures with P-P distances of 4.9 A and 4.5/5.3 A (two conformers), respectively. The main product of the reaction, however, appears to be diphosphite 8, which contains two dioxaphospha[3.1.1.]p,m,p-cyclophane subunits. The structural peculiarities of 8 were studied after subsequent oxidation to the corresponding phosphate 12. At room temperature the free rotation either of the para-phenylene rings and the meta-phenylene ring in the macrocyclic moieties are hindered as could be demonstrated by means of NOESY measurements. The latter occupies an angled position in respect to the macrocyclic plane. This leads to the existence of conformational isomers due to different relative positions of the meta-phenylene ring to the P-OR substituent (cis,trans). We could isolate the cis,cis-isomer of 12 and establish its structure by X-ray diffraction.

Journal Article↗
PubMedDate not supplied

A retention index library for commonly encountered drugs and metabolites using tri-n-alkylamines as reference compounds, nitrogen-phosphorus detectors, and dual capillary chromatography.

The retention index system is a reproducible means for the identification of drugs in toxicology samples analyzed by gas chromatography with flame ionization detectors. Nitrogen-phosphorus (NP) detectors do not respond well to the standard n-alkanes, which lack nitrogen and phosphorus groups and which are used to obtain the Kovats index. A method is presented that creates a retention index library based upon a homologous series of tri-n-alkylamines for a series of 125 drugs and metabolites. Standards were analyzed under temperature programmed conditions by simultaneous dual column chromatography using a 5% phenyl and a 50% phenyl methyl silicone fused-silica capillary column. By increasing the hydrogen and air flows to the NP detectors, the Kovats indices were calculated on the system using the n-alkanes C8 through C32. Tri-n-alkylamine indices calculated under the same conditions were compared to the Kovats indices for 14 drugs on the 5% phenyl column and for 12 drugs on the 50% phenyl column. The correlation was found to be linear. The Kovats indices on the 5% phenyl column were compared to previously reported values and found to be consistent.

Amines↗
PubMedDate not supplied

[Phospholipid composition of membrane lipids of hepatic subcellular structures in rats under the effects of different nutrition and phosphorus and fluorine compounds].

A study was made of the phospholipid composition of the membranes of the rat liver nucleus, mitochondria and microsomes under the effect of different nutrition, hydrogen fluoride and phosphine. It was established that prolonged exposure to hydrogen fluoride and phosphine resulted in alterations of the phospholipid composition of the membranes of the liver nucleus, mitochondria and microsomes. The pattern of nutrition, the diet content of retinol, tocopherol, ascorbic acid and essential amino acids (lysine, methionine, threonine) determined not only the quantitative and qualitative composition of phospholipids but also the action of the foreign substances under study on the cell membranes. The enrichment of the diet with retinol, tocopherol, ascorbic acid and thiamine reduced the membrane-damaging action of hydrogen fluoride and phosphine.

Animals↗
PubMed2003

Early developmental responses of mountain birch (Betula pubescens subsp. czerepanovii) seedlings to different concentrations of phosphorus.

Phenolic compounds, identified by high performance liquid chromatography (HPLC), and growth were investigated in the first true leaves, cotyledons, stems and roots of 2.5-week-old seedlings of mountain birch (Betula pubescens subsp. czerepanovii (Orlova) Hämetahti) grown with 1.5, 15 and 50 ppm phosphorus (P). Phenolic compounds in seeds and unfertilized 6-day-old seedlings were also studied. Seeds contained few phenolics, but had an abundance of condensed tannins. There were fewer HPLC phenolic compounds in 6-day-old seedlings than in 2.5-week-old seedlings. In 2.5-week-old seedlings, growth of the first true leaves, but not of other plant parts, was affected by P regime. In the first true leaves and stems, the concentration of condensed tannins was significantly affected by P, being higher at 1.5 ppm than at higher concentrations. The concentration of total HPLC phenolics was significantly affected by P only in stems.

Betula↗