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 1,351 records · Page 75Linked to original sources
PubMed2006

Residue formations of phosphorus hydride polymers and phosphorus oxyacids during phosphine gas fumigations of stored products.

With the extent of international usage and the critical role phosphine gas (PH3) plays in commercial pest control, identification of the residual components deposited during fumigation is mandatory. It has been postulated that these infrequent residues are primarily composed of phosphoric acid or reduced forms of phosphoric acid [hypophosphorous acid (H3PO2) and phosphorous acid (H3PO3)], due to the oxidative degradation of phosphine. Using environmental scanning electron microscopy, gas phase Fourier transform infrared spectroscopy, and X-ray fluorescence spectroscopy, the structural elucidation and formation mechanism of the yellow amorphous polyhydric phosphorus polymers (P(x)H(y)) that occur in addition to the lower oxyacids of phosphorus in residues deposited during PH3 fumigations of select tobacco commodities are explored. This research determined that nitric oxide gas (or nitrogen dioxide) initiates residue formation of phosphorus hydride polymers and phosphorus oxyacids during PH3 fumigations of stored products.

Drug Residues↗
PubMed1979

A new chemical series active against African trypanosomes: benzyltriphenylphosphonium salts.

Antitrypanosomal activity for benzyltriphenylphosphonium salts is reported for the first time. Testing was conducted using Trypanosoma rhodesiense infected mice. Of 70 phosphorus-containing compounds tested, 21 were active. Sixteen of these active chemical species were benzyltriphenylphosphonium salts. Four were nonbenzyl triphenyl compounds. The remaining active drug was a benzyldiphenylphosphonium salt.

Onium Compounds↗
PubMed2001

Phosphoramidite coupling to oligonucleotides bearing unprotected internucleosidic phosphate moieties.

The coupling of 2-cyanoethyl thymidine phosphoramidite to solid-support-bound, phosphate-unprotected oligothymidylates and their phosphorothioate analogues was studied. The yield of the coupling reaction depended on the pK(BH)()+ values of protonated nitrogen bases that served as counterions to the phosphodiester functions of oligonucleotides. To maximize the coupling efficiency, the oligonucleotides were detritylated and washed with a mixture of 0.1 M DMAP and 0.1 M 1H-tetrazole, which resulted in a 98+% coupling efficiency. The utility of the results was demonstrated in the preparation of oligonucleotides with a mixed backbone that required the successive use of H-phosphonate and phosphoramidite methods of synthesis. Using this approach, 20-mer antisense oligonucleotides containing 2'-O-(2-methoxyethyl) ribonucleoside residues and phosphorothioate and phosphoramidate internucleosidic linkages were synthesized in high yield.

Chromatography, High Pressure Liquid↗
PubMed2006

Effect of the phosphoryl substituent in the linear nitrone on the spin trapping of superoxide radical and the stability of the superoxide adduct: combined experimental and theoretical studies.

A new phosphorylated linear nitrone N-(4-hydroxybenzyliene)-1-diethoxyphosphoryl-1-methylethylamine N-oxide (4-HOPPN) was synthesized, and its X-ray structure was determined. The spin trapping ability of various kinds of free radicals by 4-HOPPN was evaluated. Kinetic study of decay of the superoxide spin adduct (4-HOPPN-OOH) shows the half-life time of 8.8 min. On the basis of the X-ray structural coordinates, theoretical analyses using density functional theory (DFT) calculations at the B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level were performed on spin-trapping reactions of superoxide radical with 4-HOPPN and PBN and three possible decay routes for their corresponding superoxide adducts. The comparative calculations on the spin-trapping reactions with superoxide radical predicted that both spin traps share an identical reaction type and have comparable potency when spin trapping superoxide radical. Analysis of the optimized geometries of 4-HOPPN-OOH and PBN-OOH reveals that an introduction of the phosphoryl group can efficiently stabilize the spin adduct through the intramolecular H-bonds, the intramolecular nonbonding attractive interactions, as well as the bulky steric protection. Examination of the decomposition thermodynamics of 4-HOPPN-OOH and PBN-OOH further supports the stabilizing role of the phosphoryl group to a linear phosphorylated spin adduct.

Crystallography, X-Ray↗
PubMed2000

Phosphatase-triggered guest release from a cyclodextrin complex.

[reaction: see text] A synthetic supramolecular system is described that models the effect of phosphoryl transfer in molecular recognition. beta-Cyclodextrin-6A-phosphate (pCD), which is shown to be a substrate of alkaline phosphatase, binds cationic aromatic guests, including anticancer agents, up to 100-fold better than native beta-CD. The above observations demonstrate that pCD is capable of releasing the guests from its cavity upon hydrolysis with the phosphatase, as also confirmed by monitoring the hydrolysis in the presence of a guest.

Alkaline Phosphatase↗
PubMed2002

Specificity of ethephon as a butyrylcholinesterase inhibitor and phosphorylating agent.

Butyrylcholinesterase (BChE) is inhibited by the plant growth regulator (2-chloroethyl)phosphonic acid (ethephon) as observed 25 years ago both in vitro and in vivo in rats and mice and more recently in subchronic studies at low doses with human subjects. The proposed mechanism is phosphorylation of the BChE active site at S198 by ethephon dianion. The present study tests this hypothesis directly using [(33)P]ethephon and recombinant BChE (rBChE) with single amino acid substitutions and further evaluates if BChE is the most sensitive esterase target in vitro and with mice in vivo. [(33)P]Ethephon labels purified rBChE but not enzymatically inactive diethylphosphoryl-rBChE (derivatized at S198 by preincubation with chlorpyrifos oxon) or several other esterases and proteins. Amino acid substitutions that greatly reduce rBChE sensitivity to ethephon are G117H and G117K in the oxyanion hole (which may interfere with hydrogen bonding between glycine-N-H and ethephon dianion) and A328F, A328W, and A328Y (perhaps by impeding access to the active site gorge). Other substitutions that do not affect sensitivity are D70N, D70K, D70G, and E197Q which are not directly involved in the catalytic triad. The effect of pH and buffer composition on inhibition supports the hypothesis that ethephon dianion is the actual phosphorylating agent without activation by divalent cations. Human plasma BChE in vitro and mouse plasma BChE in vitro and in vivo are more sensitive to ethephon than any other esterases detected by butyrylthiocholine or 1-naphthyl acetate hydrolysis in native-PAGE. All mouse liver esterases observed are less sensitive than plasma BChE to ethephon in vitro and in vivo. More than a dozen other esterases examined are 10-100-fold less sensitive than BChE to ethephon. Thus, BChE inhibition continues to be the most sensitive marker of ethephon exposure.

Amino Acid Substitution↗
PubMed2000

Reduction and activation of phosphate on the primitive earth.

Electrical discharges in water-saturated N2 containing 1-10% CH4 were shown earlier to reduce phosphate to phosphite. This mechanism was suggested as a possible source of water-soluble phosphorus-containing compounds in volcanic environments on the prebiotic Earth. We have now extended our investigations to gas mixtures in which CO2 and N2 are the main components, and studied the effect of introducing small amounts of H2 and CO. We show that surprisingly high conversions to phosphite occur in reducing mixtures and that several percent reduction of apatite occurs even in the presence of as little as 1% each of H2 and CO. We were also able to confirm a previous report of polyphosphate production as a result of heating the mineral apatite in the presence of other minerals.

Earth, Planet↗
PubMed2001

Long-term relationship between phosphorus inputs and wetland phosphorus concentrations in a northern Everglades marsh.

Assessments of long-term relationships between changes in nutrient inputs and wetland nutrient concentrations can be complicated by fluctuations in other environmental factors as well as by problems typical of long-term monitoring data. Consequently, statistical analysis of these types of data sets requires careful consideration of environmental covariates, potential biases in the monitoring design, and irregularities caused by changes in field sampling protocols. We evaluated the relationship between anthropogenic phosphorus (P) inputs and water-column total P (TP) concentrations in a northern Everglades marsh by statistically analyzing available data collected from several sampling programs over the past 20 years (1978-1997). Canal inputs of agricultural runoff contribute most of the P to the marsh and have produced a zone of enrichment within the marsh during the past few decades. Regression analyses showed that both canal and marsh TP concentrations increased during the 1980s and then decreased in the 1990s. However, the statistical relationship between canal P inputs and marsh TP, while significant, generally was weak except for marsh locations adjacent to the canal. Stronger relationships existed between marsh TP and hydrologic parameters such as marsh water depth, which is controlled by changes in weather patterns and marsh management. In particular, dry conditions during the 1980s may have contributed to observed increases in marsh P concentrations and the movement of a P 'front' further into the marsh. Higher rainfall and water depths and agricultural best management programs initiated during the 1990s have been associated with reduced P concentrations in canal waters entering the marsh. While it is anticipated that this reduction eventually will result in lower marsh TP concentrations, this effect is not yet evident, possibly due to internal loading of P from enriched marsh soils. Our findings illustrate some of the environmental factors that can complicate attempts to develop empirical relationships between P inputs and wetland P concentrations and to use such relationships to forecast changes in marsh concentrations based on past monitoring data alone.

Agriculture↗
PubMed1998

Estimations of intra- and extracellular volume and pH by 31P magnetic resonance spectroscopy: effect of therapy on RIF-1 tumours.

Quantification of metabolite or drug concentrations in living tissues requires determination of intra- and extracellular volumes. This study demonstrates how this can be achieved non-invasively by 31P magnetic resonance spectroscopy (MRS) employing dimethyl methylphosphonate (DMMP) as a marker of total water space, 3-aminopropylphosphonate (3-APP) as a marker of extracellular space and P and 3-APP as markers of intracellular pH (pH) and extracellular pH (pHe) respectively. The MRS measurements of the tumour volumes were validated by classic radiolabelling methods using 3H2O and [14C]inulin as markers of total and extracellular space respectively. The extracellular volume fraction measured by radiolabelling of RIF-1 tumours was 23 +/- 0.83% (mean +/- s.e.m. n = 9), not significantly different (P > 0.1) from that found by MRS (27 +/- 2.9%, n = 9, London, and 35 +/- 6.7, n = 14, Baltimore). In untreated RIF-1 tumours, pH was about 0.2 units higher than pHe (P < 0.01). 5-Fluorouracil (5FU) treatment (165 mg kg(-1)) caused no significant changes in either pHe or per cent extracellular volume. However significant increases in pH, 48 h after treatment (P < 0.01) correlated with decreased tumour size and improved bioenergetic status [NTP/inorganic phosphate (Pi) ratio]. This study shows the feasibility of an MR method (verified by a 'gold standard') for studying the effects of drug treatment on intra- and extracellular spaces and pH in solid tumours in vivo.

Animals↗