PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “PHOSPHORUS AND COMPOUNDS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed2006

Agricultural land use and best management practices to control nonpoint water pollution.

In recent years, improvements in point-source depuration technologies have highlighted the problems regarding agricultural nonpoint (diffuse) sources, and this issue has become highly relevant from the environmental point of view. The considerable extension of the areas responsible for this kind of pollution, together with the scarcity of funds available to local managers, make minimizing the impacts of nonpoint sources on a whole basin a virtually impossible task. This article presents the results of a study intended to pinpoint those agricultural areas, within a basin, that contribute most to water pollution, so that operations aimed at preventing and/or reducing this kind of pollution can be focused on them. With this aim, an innovative approach is presented that integrates a field-scale management model, a simple regression model, and a geographic information system (GIS). The Lake Vico basin, where recent studies highlighted a considerable increase in the trophic state, mainly caused by phosphorus (P) compounds deriving principally from the intensive cultivation of hazelnut trees in the lake basin, was chosen as the study site. Using the management model Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), the consequences, in terms of sediment yield and phosphorus export, of hazelnut tree cultivation were estimated on different areas of the basin with and without the application of a best management practice (BMP) that consists of growing meadow under the trees. The GLEAMS results were successively extended to basin scale thanks to the application of a purposely designed regression model and of a GIS. The main conclusions can be summarized as follows: The effectiveness of the above-mentioned BMP is always greater for erosion reduction than for particulate P reduction, whatever the slope value considered; moreover, the effectiveness with reference to both particulate P and sediment yield production decreases as the slope increases. The proposed approach, being completely distributed, represents a considerable step ahead compared to the semidistributed or lumped approaches, which are traditionally employed in research into tools to support the decision-making process for land-use planning aimed at water pollution control.

Agriculture↗
PubMed1997

Comparison of biocompatibility of gel-derived bioactive ceramics in macrophage culture conditions.

The behaviour of rat alveolar macrophages cultured in the presence of three new gel-derived ceramic biomaterials (CaO-P2O5-SiO2 system) with slightly different chemical compositions was examined. The abilities of these three materials to stimulate alveolar macrophages were compared. Non-treated and lipopolysaccharide-treated macrophages were used as control. The level of macrophage activation was determined by nitrite and prostaglandin E2 assay and respiratory burst measurement by chemiluminescence. The results of these studies showed different macrophage responses to these three relatively similar stimuli. Two of the studied materials were shown to be potent activators of respiratory burst and prostaglandin E2 secretion without any significant release of nitric oxide. On the contrary, the material characterized as the most surface reactive strongly affected only nitric oxide generation by the cells.

Animals↗
PubMedDate not supplied

In vivo evaluation of phosphorous-containing derivatives of dodecahydro-closo-dodecaborate for boron neutron capture therapy of gliomas and sarcomas.

The in vivo uptake of dodecahydro-closo-dodecaborate derivatives substituted with phosphate- and bisphosphonate groups was evaluated in two different experimental tumor model systems and compared to other boronated and non-boronated compounds. These phosphorous-containing boron clusters may have potential for use in boron neutron capture therapy, a chemoradiotherapeutic form of cancer treatment. Using the F98 rat glioma as a brain tumor model in syngeneic Fischer rats, there was selective tumor uptake of the phosphate derivative with 21.5 micrograms boron/g tumor versus 5.2 micrograms/g normal brain and a tumor:blood ratio of 2.7. However, this compound was toxic to test animals and lethal at relatively low doses. The uptake of the bisphosphonate by the murine K8 osteosarcoma was approximately 18 micrograms boron/g tumor with a T:Bl ratio of 7.6 and a tumor:bone ratio of 1.5. This compound was non toxic to the test animals. The results indicate that phosphate- and bisphosphonate derivatives of dodecahydro-closo-dodecaborate may have potential for BNCT of gliomas and osteosarcomas, respectively.

Animals↗
PubMed1999

Anaerobic toxicity and biodegradability of hydrolysis products of chemical warfare agents.

The toxicity and biodegradability of the main hydrolysis products of chemical warfare agents were investigated under methanogenic conditions. Among the tested substances, only MPhA does not have any toxic effect with regard to the aceticlastic methanogenic activity. The toxicity of other compounds varied between moderate (TDG, mercaptoethanol) to strong (ethanolamine, diisobutyl ester of MPhA). Biodegradability tests showed that all the products of chemical detoxification of mustard gas (ethanolamine, ethylene glycol, TDG, mercaptoethanol) can be biomineralized under methanogenic conditions. On the contrary, phosphorus-containing compounds from the chemical detoxification of nerve warfare agents (Sarin, Soman, Vx-gases) are quite persistent under these conditions.

Bacteria, Anaerobic↗
PubMed1997

Phosphorus-based combinatorial libraries: use of amino acid derivatives as synthons.

Phosphorus has been used as a scaffold to prepare combinatorial libraries of phosphoramidates in which one of the diversity elements resulted from derivatives of amino acids. A small library was prepared for analytical and characterization purposes, followed by a larger library of approximately 8800 compounds. Libraries were assembled on solid supports using the conventional pool-and-divide method, followed by cleavage from the supports at the end of the synthesis. Mass spectrometry was used to confirm that library synthesis had been successful. Individual compounds were also prepared to study the stability of compounds of this type.

Amino Acids↗
PubMed2004

Heat-pressed ionomer glass-ceramics. Part II. Mechanical property evaluation.

OBJECTIVES: A series of ionomer glasses based on the formula: 4.5SiO2-1.5P2O5-(X)Al2O3-4.5CaO-0.5CaF2, were investigated where X was varied from 3.0 to 1.5 in order to develop heat pressable dental ceramics. METHODS: The glasses were heat-pressed and then subjected to different heat-treatment cycles. The mechanical properties of the glass-ceramics were investigated, specimens were tested for hardness, fracture toughness (indentation method) and flexural strength (biaxial method). RESULTS: Good mechanical properties were obtained for heat-treatments at lower temperatures (i.e. 1150 degrees C). At intermediate heat-treatment temperatures the glass-ceramics were highly crystalline which did not favor the mechanical properties. There appears to be an inverse relationship between fracture toughness and flexural strength. High fracture toughness values of 2.7 (0.4) MPam0.5 were produced for the X = 2.8 glass heat-treated for 8 h at 1150 degrees C, the flexural strength was lowest for this heat-treatment. High flexural strengths of 194.4 (75.0) MPa were obtained by heat-treating the same glass for 1 h at 1150 degrees C. Increasing the hold time increases crystal size thereby increasing the extent of microcracking in the glass-ceramic thus lowering the flexural strength. Microcracks appear to increase the fracture toughness of the glass-ceramics probably by a crack termination mechanism. SIGNIFICANCE: Good flexural strength and high fracture toughness are attainable in this system, but appear to be mutually exclusive in the materials studied. With further investigation this system could provide clinically useful materials.

Acrylic Resins↗
PubMed1976

Phosphorus nuclear magnetic resonance of Acholeplasma laidlawii cell membranes and derived liposomes.

1. The 129 MHz 31P-NMR spectrum of Acholeplasma laidlawii membranes is very similar to the spectrum of the derived liposomes and is a typical "solid state" spectrum in which the major contribution to the linewidth is made by the chemical shift anisotropy. From the value of the chemical shift anisotropy an order parameter of 0.15 is estimated for the lipid phosphates in both membranes. 2. The 31P-NMR spectrum of the A. laidlawii membrane is insensitive to pronase digestion of 4-60% of the membrane proteins and subsequent cytochrome C binding. These results indicate that either no strong lipid polar headgroup-protein interactions occur in the membrane or that the lipid-protein "complexes" in the membrane have a fast rotation (Tc shorter than 10(-6)S) along an axis perpendicular to the plane of the membrane. 3. Phospholipase A2 degrades all the phosphatidylglycerol in the membrane. The resulting membrane contains a phosphoglycolipid as the sole phosphorus-containing compound. The 31P-NMR spectrum of these membranes is identical to the spectrum of the native membranes suggesting a similar motion for the phosphate groups in both lipids. 4. Ca2+ binding to liposomes prepared from either the total polar lipids or the total phosphorus-containing lipids isolated from the A. laidlawii membrane does not affect the 21P-NMR spectrum. 5. The 31P-NMR spectrum of the membranes and derived liposomes, however, is sensitive to lipid phase transitions. When the membrane lipids are in the gel state a broadening of the 31P resonance occurs demonstrating that the polar head group motion in a biological membrane is more restricted below the lipid-phase transition temperature.

Acholeplasma laidlawii↗
PubMed1989

[Determination of the activity of neurotoxic esterase in the peripheral blood lymphocytes for assessing the action of organophosphorus compounds].

It was shown on a model of intoxication of hens with aphos possessing a selective neuroparalytic action that the target-enzyme neurotoxic esterase changed its activity in the brain, spleen and lymphocytes of the peripheral blood. The authors describe a method of determination of the activity of neurotoxic esterase in human peripheral blood lymphocytes that may be used for biomonitoring of the effect of phosphorus organic compounds possessing a delayed neurotoxic action.

Animals↗
PubMed2001

Accumulation of magnesium as well as calcium and phosphorus in Japanese monkey arteries with aging.

To examine whether an accumulation of elements in the arteries with aging differs between human and animal, the authors investigated the relationships among element contents in the arteries of the Japanese monkeys. The Japanese monkeys consisted of five males and four females, ranging in age from 2 to 29 yr. The aorta, common and external iliac, femoral, common carotid, subclavian, and axillary arteries were resected from the monkeys and element contents were determined by inductively coupled plasma-atomic emission spectrometry. It was found that there were very high correlations between calcium and phosphorus contents, between calcium and magnesium contents, and between phosphorus and magnesium contents in all of the monkey arteries. In addition, significant correlations were found among the other element contents in some, but not all of the arteries. These results were consistent with the foregoing findings of the human arteries. It is likely that magnesium forms compounds with phosphorus or calcium in the monkey arteries.

Age Factors↗
PubMed2003

Polyphosphoric acid trimethylsilyl ester promoted intramolecular acylation of an olefin by a carboxylic acid: convenient construction of C-18-functionalized delta14-hecogenin acetate.

[reaction: see text]. Polyphosphoric acid trimethylsilyl ester (PPSE)-promoted intramolecular Friedel-Crafts reactions on a nonaromatic carboxylic acid system have been investigated. Studies led to the synthesis of C-18 functionalized steroidal compounds 5 and 9a-d with strict retention of the spiroketals. Isomerization of spiroketal 9e was studied.

Acylation↗
PubMed2006

A combined stopped-flow, electrospray ionization mass spectrometry and (31)P NMR study on the acetic acid-mediated fragmentation of the hydroxo-chalcogenide cluster [W(3)Se(4)(OH)(3)(dmpe)(3)](+) (dmpe = 1,2-bis(dimethylphosphanyl)ethane) to yield the dinuclear [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) complex.

The reaction of the incomplete-cuboidal [W(3)Se(4)(OH)(3)(dmpe)(3)](+) ([1](+)) cluster with acetic acid in acetonitrile solution leads to cluster fragmentation with formation of the dinuclear [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) ([2](+)) complex. The X-ray structure of [2]PF(6) presents two equivalent metal centres bridged by one acetate ligand. Each W atom is additionally coordinated by one terminal selenium atom, two bridging selenido and two diphosphane phosphorus atoms in an essentially octahedral environment. Stopped-flow and conventional UV-vis studies indicate that fragmentation of [1](+) into [2](+) occurs through a complex mechanism. Three steps can be distinguished in the stopped-flow time scale, all of them showing a first order dependence with respect to the acetic acid concentration, followed by very slow spectral changes that lead to the formation of [2](+). Phosphorus NMR, electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) have been used to identify the nature of the reaction intermediates formed in the different steps. These studies indicate that the first two steps correspond to the formal substitutions of the hydroxo ligands at two metal centres by terminal acetate ligands. The third step involves bridging of one of the terminal acetate ligands, which actually prepares the trinuclear cluster to afford the acetate-bridged [W(2)Se(2)(mu-Se)(2)(mu-CH(3)CO(2))(dmpe)(2)](+) ([2](+)) complex. Although the precise details of the final conversion to [2](+) have not been established, the results obtained by combination of the different experimental techniques provide a complete picture of the speciation of the cluster [1](+) in acetonitrile solutions containing acetic acid.

Acetic Acid↗
PubMed2000

[Coupling effect of water and fertilizers on spring wheat yield in semi-arid area of western Liaoning Province].

With optimum saturation design, a field experiment was conducted to study the coupling effect of water and fertilizers on spring wheat yield in semiarid area of western Liaoning Province. Regression model shows that water was the most important factor affecting spring wheat yield. Under natural raining and when the upper and the lower limit of irrigation was 360 mm and 45 mm, respectively, N was the most sensitive factor, water was the second, and P was the third. The effects of N, P and water on yield were statistically significant, and met the law of diminishing return. The most economic matching pattern of N, P and water was N 186 kg.hm-2, P 63 kg.hm-2, and water 300 mm. Properly increasing phosphorus fertilizer at the lack of water could strengthen the drought-resistance of spring wheat.

China↗
PubMed2004

CaO--P2O5--Na2O-based sintering additives for hydroxyapatite (HAp) ceramics.

We have assessed the effect of CaO--P2O5--Na2O-based sintering additives on mechanical and biological properties of hydroxyapatite (HAp) ceramics. Five different compositions of sintering additives were selected and prepared by mixing of CaO, P2O5, and Na2CO3 powders. 2.5 wt% of each additive was combined with commercial HAp powder, separately, followed by ball milling, and sintering at 1250 degrees C and 1300 degrees C in a muffle furnace. Green and sintered densities of the compacts were analyzed for the influence of additives on densification of HAp. Phase analyses were carried out using an X-ray diffractometer. Vickers microhardness testing was used to evaluate hardness of sintered compacts of different compositions. A maximum microhardness of 4.6 (+/- 0.28) GPa was attained for a composition with 2.5 wt% addition of CaO:P2O5:Na2O in the ratio of 3:3:4. Results from mechanical property evaluation showed that some of these sintering additives improved failure strength of HAp under compressive loading. Maximum compressive strength was observed for samples with 2.5 wt% addition of CaO. Average failure strength for this set of samples was calculated to be 220 (+/- 50) MPa. Cytotoxicity, and cell attachment studies were carried out using a modified human osteoblast cell line called OPC-1. In vitro results showed that these compositions were non-toxic. Some sintering aids enhanced cell attachment and proliferation, which was revealed from SEM examination of the scaffolds seeded with OPC-1 cells.

Bone Substitutes↗
PubMed1992

Preventive effect of beta-alanyl-L-histidinato zinc on bone metabolism in rats fed on low-calcium and vitamin D-deficient diets.

The effect of beta-alanyl-L-histidinato zinc (AHZ) on bone metabolism in the femoral diaphysis of rats fed on low-calcium and vitamin D-deficient diets was investigated. Rats were orally administered AHZ (10, 30, and 100 mg/kg per day) for 14 days and were killed on the 15th day. Feeding with low-calcium and vitamin D-deficient diets caused a significant decrease in serum 25-hydroxy-vitamin D3, calcium, and inorganic phosphorus concentrations. These decreases were not prevented by AHZ administration. Meanwhile, the femoral-diaphyseal calcium and phosphorus contents were significantly reduced by feeding with the deficient diets. Decrease in bone calcium content was significantly prevented by the doses of 30 and 100 mg AHZ/kg. Furthermore, the dose of 100 mg AHZ/kg produced a significant increase in bone deoxyribonucleic acid (DNA) content and alkaline phosphatase activity in rats fed on the deficient diets. Bone zinc content in the deficient rats was significantly increased by the doses of AHZ (30 and 100 mg/kg). The present results suggest that oral administration of AHZ has a preventive effect in the development of deteriorating bone metabolism in rats fed on low-calcium and vitamin D-deficient diets.

Administration, Oral↗
PubMed1988

Polyamine inhibition of lipoperoxidation. The influence of polyamines on iron oxidation in the presence of compounds mimicking phospholipid polar heads.

Polyamines appear to inhibit peroxidation of vesicles containing acidic phospholipids. A correlation exists between polyamine binding to phospholipid vesicles and its protective effect. However, phosphatidylinositol-containing vesicles which bind spermine are not protected by the polyamine [Tadolini, Cabrini, Landi, Varani & Pasquali (1985) Biogenic Amines 3, 97-106]. In the present paper I tested the hypothesis that polyamines, in particular spermine, by forming a ternary complex with iron and the phospholipid polar head may change the susceptibility of Fe2+ to autoxidation and thus its ability to generate free oxygen radicals. Different compounds mimicking phospholipid polar heads were studied, namely AMP, mimicking phosphatidic acid, CDP-choline, mimicking phosphatidylcholine, and glycerophosphoinositol, mimicking phosphatidylinositol. The results support the proposed hypothesis. In the presence of CDP-choline or of glycerophosphoinositol, spermine poorly affects Fe2+ autoxidation, whereas a considerable inhibition is observed in the presence of AMP. The ability of other phosphorus-containing compounds (ATP, ADP, cyclic AMP, sodium phosphate) to affect Fe2+ autoxidation in the presence of polyamines was also evaluated to understand the molecular mechanism of this phenomenon. It is proposed that polyamines may be part of the passive cellular defence mechanism against the oxidative damage caused by Fe2+.

Adenine Nucleotides↗
PubMed1981

Effect of lead ingestion on functions of vitamin D and its metabolites.

A study of the effect of ingestion of lead on the metabolism and function of vitamin D was carried out in rats fed diets varying in calcium and phosphorus content. The ingestion of 0.82% lead as lead acetate suppressed plasma levels of 1,25-dihydroxycholecalciferol in rats fed either a low phosphorus or a low calcium diet while it had no effect on this parameter in rats fet either a high calcium diet or a normal phosphorus diet. Most important, the ingestion of lead totally blocked the intestinal calcium transport response to cholecalciferol, 25-hydroxycholecalciferol and 1,25-dihydroxycholecalciferol. On the other hand, the ingestion of lead acetate had no influence on the mobilization of calcium from bone, the elevation of serum inorganic phosphorus and in the mineralization of rachitic bone in the same animals. Thus by the feeding of 0.82% lead on the intestinal responses to vitamin D and its metabolites was greatest in animals fed a low calcium or a low phosphorus diet, it was present with all diets tested.

Animals↗