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At least 379 records · Page 21Linked to original sources
PubMed1979

[Studies of the consecutive hydrolysis of dipeptidyl-4-(phenylazo)-phenylamides by an aminopeptidase from Brassica napus].

The relatively alanine-specific amino peptidase from Brassica napus hydrolyzes dipeptidyl-4-(phenylazo)-phenylamide according to a consecutive mechanism. Enzyme-kinetic studies of dipeptidyl-4-(phenylazo)-phenylamides carried out by means of spectrometrical procedures of measurement are only possible when the increase in the concentration of the fission product p-aminoazobenzene is recorded. For assessing the kinetic parameters of the intermediary steps of the hydrolysis of dipeptidyl-4-(phenylazo)-phenylamides a function is derived describing the dependence of the concentration of fission products of p-aminoazobenzene on reaction time. The satisfactory correspondence of the kinetic parameters calculated for the intermediary-originating substrate L-ala-4-(phenylazo)-phenylamide as substrate demonstrates the applicability of the procedure described in the present paper.

Aminopeptidases↗
PubMed1984

Oxidation of lipids. 7. Oxidation of phosphatidylcholines in homogeneous solution and in water dispersion.

The rates and products of the oxidations of phosphatidylcholines (PCs) in organic homogeneous solutions and as multilamellar liposomes in an aqueous dispersion were studied at 50 degrees C initiated by oil-soluble and water-soluble azo compounds and with the aim primarily of elucidating the effect of substrate and the reaction medium. Polyunsaturated fatty acids were oxidized exclusively among the fatty acids in PC. The product distribution was determined by the number of double bonds: in the oxidation of methyl linoleate and dilinoleoyl PC, the conjugated diene hydroperoxides were formed almost quantitatively, whereas in the oxidation of PC and polyunsaturated fatty acids having three or more double-bonds, cyclic peroxides were also formed. The oxidizability of PC was dependent on the content of doubly allylic hydrogens and their reactivities were suggested to be similar, independent of parent substrate and reaction medium, although the oxidizability of PC in nonpolar organic solvents is markedly enhanced by the formation of reverse-phase micelles.

Animals↗
PubMed1984

Inhibition of oxidation of methyl linoleate in solution by vitamin E and vitamin C.

The oxidation of methyl linoleate in solution initiated with azo compounds has been studied in the absence and presence of vitamin E and vitamin C. Both vitamin E and vitamin C acted as a chain-breaking antioxidant and they suppressed the oxidation and produced an induction period. The inhibition rate constant for the scavenging of peroxy radical was calculated at 37 degrees C as kinh = 5.1 X 10(5) M-1 s-1 and 7.5 X 10(4) M-1 s-1 for vitamin E and vitamin C, respectively. It was suggested that each vitamin E could trap two peroxy radicals, whereas vitamin C could trap only one peroxy radical under the reaction conditions employed in this study. When both vitamin E and vitamin C were present, the oxidation was suppressed quite efficiently and the apparent inhibition rate constant was obtained as kinh = 4.0 X 10(5) M-1 s-1. Furthermore, vitamin E remained almost unchanged and only vitamin C was consumed at the initial stage and vitamin E was consumed after vitamin C was exhausted. It was concluded that vitamin E trapped the peroxy radical and the resulting alpha-chromanoxy radical reacted with vitamin C to regenerate vitamin E.

Ascorbic Acid↗
PubMed1984

[Cancer of the bladder occurring in occupational dye users: report of two cases].

Two cases of occupational dye users were found to have bladder tumors. Case 1 was a 32-year-old male, who had worked at the Yuzen process for the last 7 years. Multiple papillary tumors were seen on the whole wall of the bladder endoscopically and total cysto-urethrectomy and ileal conduit were performed. The pathological examination of the bladder tumors revealed non-invasive transitional cell carcinoma grade I--II. His post-operative course has been uneventful without any signs of tumor recurrence for 31 months. Case 2 was a 46-year-old male, who had worked at the throwing stained silk for the last 28 years. He suffered from severe hematuria for six months. A big egg-sized nonpapillary tumor on the posterior wall of the bladder was found and bilateral cutaneous-ureterostomy was performed but severe gross hematuria remained. Total cysto-urethrectomy was performed but the patient died of progressive disease 5 months later. The bladder tumor was a grade III invasive transitional cell carcinoma. The fact that process workers in the dye manufacturing industry have a high risk of bladder cancer has been well known and mass screening examination on them has been systematically performed. Though there is a higher relative risk of bladder cancer in occupational dye users, systematic screening examination has not been done. We emphasize the necessity for establishing systematic mass screening examination of occupational dye users for the early diagnosis of bladder cancer.

Adult↗
PubMedDate not supplied

[Pharmacokinetics of 1-(4'-oxyphenyl)-2-(3'-phenyl-thiopropyl-amino) propane-1-01 hydrochloride (Istiod) in the rat].

The pharmacokinetics (serum, urinary and biliary concentrations) of Isotiod have been studied in rats. Doses exploited the property of the molecule in an alkaline medium with a diazonium salt to form coloured azo compounds. In rats Isotiod determines blood concentrations whose intensity and duration are proportional to the dose and route of administration; notable quantities of the drug are eliminated by the urinary way and a small quantity by the bile way with a personal technique.

Animals↗
PubMedDate not supplied

Liquid chromatographic determination of 2-chloro-4-nitroaniline, 2-naphthol, and 2,4-dinitroaniline in D&C red no. 36.

A method is described for the determination of the intermediates and a related impurity in D&C Red No. 36 by reversed-phase liquid chromatography. This method may be used to ensure that limits set forth in the Code of Federal Regulations on the amounts of these 3 impurities in the color are not exceeded. The pigment is dissolved in boiling dioxane and then precipitated. The filtrate is chromatographed by isocratic elution, and then the column is washed and reequilibrated. Impurities were identified as 2-chloro-4-nitroaniline (2-Cl-4-NA), 2-naphthol, and 2,4-dinitroaniline (2,4-DNA) by comparison of their retention times and spectra with those of standards. Peak area calibrations were linear to at least 0.375% 2-Cl-4-NA, 1.25% 2-naphthol, and 0.025% 2,4-DNA, all with zero intercepts. At the specification levels, 99% confidence limits were 0.30 +/- 0.006% for 2-Cl-4-NA, 1.0 +/- 0.03% for 2-naphthol, and 0.020 +/- 0.0004% for 2,4-DNA. The limits of determination calculated from calibration data were 0.019% for 2-Cl-4-NA, 0.10% for 2-naphthol, and 0.0014% for 2,4-DNA at the 99% confidence level. Recoveries were 100-104% for 2-Cl-4-NA added to purified D&C Red No. 36, 100% for 2-naphthol, and 100-110% for 2,4-DNA; relative standard deviations were 0.8-3.4%. A survey of certified D&C Red No. 36 samples showed that the batches contained higher levels of intermediates than were determined previously by a cellulose column method in which the pigment was not dissolved.

Aniline Compounds↗