Aqueous Sodium Phosphate Research Articles

Antiinflammatory polymer‐bound steroids for topical applications II. Controlled release of the steroids

AbstractThe release of hydrocortisone and dexamethasone due to hydrolysis of the carbonate linkage from the polymeric supports of poly(oxyethyleneglycol), hydroxypropyl cellulose, and N‐vinylpyrrolidone/hydrocortisone–21CH2–vinylcarbonate copolymer was observed in a living system, by induction of αGPDH activity in rat C6 glial cells, and in vitro by a kinetic study of release in aqueous sodium phosphate buffer medium. The glucocorticoid release is pH and temperature dependent and highly sensitive to steric hindrance. In vivo testing on antiinflammatory activity in rats with poly(oxyethyleneglycol) and hydroxypropyl cellulose bound dexamethasone was performed. However, it produced negative results probably due to difficulty in splitting the carbonate linkage in the inflammatory region of acidic pH values.

Thiol-catalyzed formation of lactate and glycerate from glyceraldehyde.

The formation of lactate from glyceraldehyde is catalyzed by the thiol, N-acetylcysteine, at ambient temperature in aqueous sodium phosphate (pH 7.0). The rate of lactate formation is more rapid at higher concentrations of sodium phosphate and is essentially the same in the presence and absence of oxygen. The formation of lactate is efficient, but proceeds slowly with an 8.8% yield of lactate after 16 days from 10 mM glyceraldehyde in the presence of 12.5 mM N-acetylcysteine and 500 mM sodium phosphate (pH 7.0). The formation of glycerate from glyceraldehyde, that occurs in the presence of oxygen and to a small extent when oxygen has been removed, is also catalyzed by the thiol, N-acetylcysteine, under the same conditions. The dramatic increase in the rate of glycerate formation that is brought about by the thiol, N-acetylcysteine, is accompanied by an equally dramatic decrease in the rates of production of glycolate and formate. Presumably, the thiol-dependent formation of lactate and glycerate occurs via their respective thioesters. The significance of these reactions to molecular evolution is discussed.

Improved recovery of ovalbumin by reversed-phase high-performance liquid chromatography

Reversed-phase high-performance liquid chromatography (RP-HPLC) is an unique method of separating proteins and peptides mainly in the order of their hydrophobicities . l-9 However, it has not been possible to achieve satisfactorily reproducible analyses of labile proteins such as ovalbumin owing to their relatively low recoveries. We wished to improve the RP-HPLC analysis of ovalbumin by increasing its recovery, and have studied the reproducibility and recovery by changing the procedure and conditions using commercially available column-packing materials and apparatus. We modified the method of Month and Dehnen’ to enable a recovery greater than 80% of ovalbumin: ethylene glycol was used instead of methyl Cellosolve (2methoxyethanol); proteins injected did not make contact with organic solvent; the loading carrier (solvent A) was aqueous sodium phosphate solution and the column temperature was maintained at 15°C.

Two-liquid-phase boundaries and critical phenomena at 275-400.degree.C; for high-temperature aqueous potassium phosphate and sodium phosphate solutions. Potential applications for steam generators

(1) Rao, M. V. P.; Naidu, P. R. Can. J . Chem. 1974, 52, 788. (2) Reo, M. V. P.; Naidu, P. R. J . Chem. Thermodyn. 1978, 8, 73. (3) Rao, M. V. P.; Naidu, P. R. J . Chem. Thermodyn. 1978. 8 , 96. (4) Rao, M. V. P.; NaMu, P. R. Can. J . Chem. 1978, 54, 2280. Received for review July 8, 1981. Accepted November 18, 1981. S.S.R. is thankful to the University &ants Comission for giving financial asslstance under the faculty Improvement program.

Liquid-chromatographic analysis for urinary porphyrins.

Urinary porphyrins are separated, according to number of carboxyl groups, in a system consisting of a mu-Bondapak C18 stationary phase and a mobile phase of methanol and aqueous sodium phosphate (pH 3.5) in a linear gradient. The specimen is prepared simply by adjusting the pH of a 5-mL sample to 2.0 and removing solids by centrifugation. The eluted porphyrins are measured fluorometrically. Naturally occurring non-porphyrin fluorescent substances are eluted ahead of the porphyrins. Chromatography requires about 20 min, and a re-establishment of initial conditions requires an additional 15 min.

Chromatography of xanthines on ion-exchange resins

Short columns of a 4% crosslinked cation-exchange resin gave good chromatography of xanthines, including caffeine, theophylline and hypoxanthine, and related polar aromatic compounds. Elution volumes and sequences can be modified by changing pH, solvent composition and resin counter-ion. A macroporous cation-exchange resin showed exaggerated counter-ion effects. A method is described for determining caffeine and theophylline in blood serum, using the 4% crosslinked resin with aqueous sodium phosphate eluent of pH 7.5; the temperature was 65°. Detection limits are 10 ng and less.

Phase equilibria in aqueous sodium phosphate solutions at elevated temperatures

Solubility and phase studies for the system Na2O–P2O5–H2O have been carried out at 251 and 300 °C and at the vapour pressures of the solutions. The experiments have been largely confined to the region of composition between the mol ratio Na2O : P2O5= 1.8 and 10.0. At both temperatures, the more alkaline saturated solutions are in equilibrium with a solid phase, 11 Na2O·4P2O5·3H2O, a complex orthophosphate. The less alkaline saturated solutions are in equilibrium with Na2[HPO4] at 251 °C, and with Na4[P2O7] at 300 °C. However, at the higher temperature, a region of liquid–liquid immiscibility also exists.

Thin-Layer Chromatographic Differentiation of Amphetamine from Other Primary-Amine Drugs in Urine

Abstract We describe a thin-layer chromatographic procedure for distinguishing among amphetamine, mescaline, 4-methyl-2,5-dimethoxyamphetamine (STP), 3,4-methylenedioxyamphetamine (MDA), phenylpropanolamine, chlorphentermine, β-phenylethylamine, benzocaine, and procaine. These compounds may be encountered in urine-screening programs, and all except MDA are well separated from amphetamine (a fact not previously established) as well as from each other. They are revealed by sequentially spraying with ethanolic phenylacetaldehyde—ninhydrin and aqueous sodium phosphate. The resulting yellow spots fluoresce green on heating. The aromatic amines fluoresce poorly. MDA is distinguished from amphetamine by overspraying with chromotropic acid. Detection limits and Rf values are reported. Fluorescence spectra of the aliphatic amines are similar.

Circular dichroism of a membrane protein of Neurospora crassa

Membrane protein of a mutant of Neurospora crassa has been isolated in aqueous sodium phosphate buffer without employing a chemical agent such as urea, detergent, or organic solvent. The protein moved in a single band on sodium dodecyl sulfate gel electrophoresis and as well on non-SDS gel electrophoresis. The circular dichroism spectrum of the protein exhibited the characteristic low ellipticity but no red shift.

The soluble proteins of bovine hide II. Extraction by aqueous sodium phosphate and half-saturated lime

Following extraction by saline solutions, fresh bovine hides have been treated with M/15 sodium phosphate and half-saturated lime. The bulk of the extracted nitrogen is lost on dialysis. The nitrogen content of the non-dialysable phosphate-extracted material is considerably lower than for the corresponding saline extract, indicating the presence of non-protein constituents. The extracted materials contain little or no collagen but appear very similar electrophoretically to serum. However, additional components, some probably containing hyaluronic acid, occur in the phosphate-extracted material and probably more so in the lime extracts. The chief component (A) occurring in all extracts is indistinguishable electrophoretically from bovine serum albumin, but is slower sedimenting, probably as a result of conjugation to different extents with uncharged, low density, non-protein material. Other components are comparable with serum globulins electrophoretically and in their sedimentation properties, but, in view of the occurrence of non-serum and non-protein components also, exact correspondence in these and general properties was not to be anticipated. Present results differ considerably from those previously published for extracts of young rabbit skin and either an age- or species-difference must be responsible.