SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
A compound having structures of both vitamins E and C, L-ascorbic acid dl-alpha-tocopherol phosphoric acid diester potassium salt (EPC-K), which was proven to have both anti-oxidative3%!d moisturizing effects, has been formulated in the quasi drug hair growing products to mainly prevent dandruff and itching which may be one of the causes for the hair loss. Stabilities of EPC-K in 75% ethanolic solutions with various pHs (2-10) were examined extensively by storing them at 50 degrees C for 30 d and by sunlight exposure for 30 d. Decomposition of EPC-K was only observed under pH 2 at a level of 50% and under sunlight exposure at 25% level. A main decomposition product was identified as tocopheryl phosphate (EP), suggesting that a decomposition route was through hydrolysis. EPC-K was found to decompose by as much as 20% under 30 d storage at 50 degrees C when the concentration of the aqueous ethanolic solution was 0-30%. 1H, 13C and 31P-NMR studies in addition to a micelle formation test using pyrene fluorescent probe revealed that EPC-K formed a micelle at such low concentration of ethanol, which was assumed to be a cause for unstableness of EPC-K in that range. Hydrolytic decomposition of EPC-K was found by the reaction rate study to be a pseudo first order reaction with activation energy of 16.98 kcal/mol.
Phosphoric acid plant wastewater containing fluoride, phosphate and chemical oxygen demand etc., was treated using electrooxidation and electroflocculation methods. A maximum of 82% F- and 22.7% COD were removed using Ti/Pt(5c) under electrooxidative conditions. Electrooxidation with respect to F- removal is found mass-transfer limited, and removals below 5-6 mg/L F- are not achievable. Electroflocculation using Al anode resulted in better removal of F-, COD and PO4(3-). The various results obtained are discussed in this paper.
A series of lipid phosphoric acids, including 1-O-alkyl-2-lyso-glycerophosphoric acid, 1-O-acyl-2-lyso-glycerophosphoric acid, hexadecylpropanediolphosphoric acid, N-acyl-2-aminoethanolphosphoric acid, sphingosine phosphoric acid, and certain homologues and analogues, were synthesized and characterized by thin-layer chromatography, fast-atom bombardment mass spectrometry, and their ability to aggregate human platelets. The presence of a receptor for these lipid phosphoric acids that is distinct from the PAF receptor is strongly suggested from experiments involving a desensitization procedure, platelet-activating factor (PAF) receptor antagonists, and inhibitors of the lipid phosphoric acids. The unique features of the interaction of these lipid phosphoric acids with platelets include: (a) evidence for a separate receptor(s) for this diverse group of synthetic compounds, (b) no requirement for stereospecificity (i.e., no glycerol backbone), and (c) a structural requirement for a long-chain hydrocarbon residue covalently bound to a phosphoric acid residue. In the interaction of these compounds with the platelet, it is mandatory that extracellular Ca2+ and ADP be present for maximum biological activity. The potential involvement of a lipid phosphoric acid receptor, which could form a component of the activation pathway associated with various lysophospholipids and analogues, such as PAF, via a phospholipase D activation, is discussed.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The use of organophosphorus preparations in the treatment of ectoparasites and endoparasites of pigs is discussed. Treatment of 43 store pigs with preparations produced in the German Democratic Republic by washing and by the pour-on method resulted in considerable inactivation of acetylcholinesterase, which implies good systemic action. Overdosage increased this effect, but without producing signs of toxicity. The oral dosages for pigs cited in the literature were confirmed. Repeated treatment was recommended for the best results, as pigs rapidly break down the preparations. It is necessary to take into account adverse effects of oral administration on palatability of the ration and on weight gain. Addition of a preparation to a batch of food for a group of pigs is likely to be less successful than individual dosing, which is the best method for sows.
The use of organophosphorus preparations for the control of ectoparasites and endoparasites of sheep, particularly systemic application, is discussed. Experiments on 13 groups of sheep with five preparations produced in the German Democratic Republic in various formulations and concentrations showed that external application had good contact activity, but little was absorbed. Acetylcholinesterase activity was not inhibited, except by pour-on application of doses several times the normal dose. The preparations were arranged in order of cholinesterase inhibition. In contrast to cattle, diminished cholinesterase activity was unreliable as in indicator of systemic toxicity of organophosphorus preparations in sheep.
Explore the source record for details and available documents.
An earlier study showed that Scotchbond Multi-Purpose, which uses a 10% maleic acid dentin/enamel etchant, had lower enamel bond strengths than those typically obtained by etching with 35-40% phosphoric acid. Therefore, the possibility of substituting phosphoric acid for maleic acid in the Scotchbond system might be considered. The purpose of this study was to evaluate the dentin bond strengths of Scotchbond Multi-Purpose when various phosphoric acid agents were used to etch the dentin. Proximal dentin surfaces of extracted human molars were etched with 10% maleic acid, 35% phosphoric acid, 32% phosphoric acid, 10% phosphoric acid or 25% phosphoric acid with aluminum oxalate (Etch 'N' Seal). Scotchbond Multi-Purpose Primer and Adhesive were applied as directed and composite posts were bonded to the dentin. After thermocycling, the composite was fractured off using an Instron testing machine. Mean dentin bond strengths were 17.3 MPa for 10% maleic acid, 17.2 MPa for 10% phosphoric acid, 15.2 MPa for 35% phosphoric acid, 13.6 MPa for 32% phosphoric acid, and 5.2 MPa for Etch 'N' Seal. The bond strengths for all groups except Etch 'N' Seal were statistically similar.
Explore the source record for details and available documents.
We examined the effects of phosphoric acid, the most common enamel etchant in composite resin therapy, on dentine collagen. Dentine collagen pretreated with 7M phosphoric acid was shown to be more susceptible to trypsin digestion than untreated collagen. This susceptibility increased with increasing duration of exposure to the acid. The results indicate that phosphoric acid induces a conformational change in dentine collagen (denaturation or perturbation) similar to that observed with 0.39 M HCl, which has a similar pH value (0.65). However, phosphoric acid-pretreated dentine collagen, when treated with tannic acid for 2 h, became as resistant to tryptic digestion as intact dentine collagen. The present results suggest that tannic acid may work as a dentine conditioner in composite resin therapy, in view of the fact that phosphoric acid etchant is applied, either deliberately or inadvertently, to dentine, and would thus induce denaturation or perturbation of collagen.
An improved synthesis of two lipid phosphoric acids, N-palmitoyl-L-serine phosphoric acid (NP-Ser-PA) and N-palmitoyl-L-tyrosine phosphoric acid (NP-Tyr-PA), from the benzyl esters of L-serine and L-tyrosine is described. The sequence of N-acylation, followed by phosphitylation with N, N-diisopropyl dibenzyl phosphoramidite, oxidation to the corresponding phosphate triesters, and simultaneous debenzylation of the dibenzyl phosphate and benzyl carboxylic esters gave NP-Ser-PA and NP-Tyr-PA in high overall yields. NP-Ser-PA and NP-Tyr-PA and their D stereoisomers were potent reversible inhibitors of the lysophosphatidic acid receptors expressed in Xenopus oocytes, thus providing prototypic structures for the development of inhibitors of the lysophosphatidate family of phospholipid growth factors.
Phosphopeptides are often detected with low efficiency by MALDI MS analysis of peptide mixtures. In an effort to improve the phosphopeptide ion response in MALDI MS, we investigated the effects of adding low concentrations of organic and inorganic acids during peptide sample preparation in 2,5-dihydroxybenzoic acid (2,5-DHB) matrix. Phosphoric acid in combination with 2,5-DHB matrix significantly enhanced phosphopeptide ion signals in MALDI mass spectra of crude peptide mixtures derived from the phosphorylated proteins alpha-casein and beta-casein. The beneficial effects of adding up to 1% phosphoric acid to 2,5-DHB were also observed in LC-MALDI-MS analysis of tryptic phosphopeptides of B. subtilis PrkC phosphoprotein. Finally, the mass resolution of MALDI mass spectra of intact proteins was significantly improved by using phosphoric acid in 2,5-DHB matrix.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The levels of phosphorous acid residues in apples after foliar fertilization with P fertilizers and after treatment with a phosphonate fungicide (Fosetyl-Al) were determined and compared. Two field trials and a glasshouse experiment, using different genotypes and plants of different age, were carried out and monitored over a three-year period. Phosphorous acid residues were found in apples after application of foliar P fertilizers. Concentrations of the residues ranged between 0.02 and 14 mg kg(-1) depending on the phosphorous acid content in the fertilizer used and the plant size and yield. The treatments induced an accumulation of the residue in the course of the experiments, which in some cases reached a level exceeding the maximum limit set by EU legislation. Residues were also detected in other plant organs, i.e., roots and buds. Plants treated with Fosetyl-Al contained phosphorous acid residues in their fruits and buds two years after the suspension of the treatment, suggesting a long-term persistence of the substance in plant storage organs. A second experiment, involving treatment of trees with seven foliar fertilizers of different composition, also induced accumulation of phosphorous acid residues in fruits. It is concluded that a wide array of foliar products containing phosphorous acid, even as a minor component, could mimic the residue effect of phosphonate fungicide treatments.