Search PubMed⌕ Search

Biomedical subjects

S Pfeifer

Publications and source records attributed to S Pfeifer.

At least 91 records · Page 5Linked to original sources
PubMed1981

Avian acute leukemia virus OK10 has an 8.2-kilobase genome and modified glycoprotein gp 78.

We have analyzed the structure of OK10-BM virus, an avian acute leukemia virus produced by a bone marrow-derived cell line of macrophage origin, and compared it with that of OK10 AV, an associated virus originally present in the OK10 virus stock. The RNAs of OK10-BM virus and OK10 AV had the same mobility in agarose gels, corresponding to 8.0 to 8.5 kilobases, a size considerably larger than that of the transforming component (5 to 6 kb) of most other avian acute leukemia viruses. Fingerprint analysis showed a close relationship between OK10-BM virus and OK10 AV RNAs. The polypeptide compositions of OK10-BM and OK10 AV viruses were similar except for the envelope glycoproteins. In analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the large envelope glycoprotein of OK10-BM virus migrated at M(r) = 78,000 (gp78), whereas OK10 AV had the characteristic 85,000-dalton glycoprotein (gp85) of nondefective avian leukemia viruses. gp78 was weakly labeled with methionine, glycine, proline, or mannose, suggesting that purified OK10-BM virus had reduced amounts of the modified envelope glycoprotein. In cell-free rabbit reticulocyte lysates, OK10-BM virion RNA directed the synthesis of a 200,000-dalton polypeptide (p200), a 180,000-dalton polypeptide (pr180), and a 76,000-dalton polypeptide (pr76), whereas OK10 AV RNA gave rise only to pr180 and pr76, suggesting that p200 may represent an OK10-BM-encoded transforming protein. No biochemical evidence for the presence of an associated helper virus was found in the OK10-BM virus population produced by the macrophage cell line. However, when OK10-BM virus was serially passaged in chicken embryo fibroblasts, a virus having structural properties similar to those of OK10 AV (OK10 AV-specific oligonucleotides and gp85) appeared after three passages. Moreover, nonproducer clones of transformed cells could be readily obtained in OK10-BM virus-infected quail cell cultures. It is thus likely that the bone marrow-derived macrophage cell line produces a transforming virus defective in its env gene and low amounts of an associated helper virus, which upon transfer to fibroblasts is preferentially replicated.

Animals↗
PubMed1981

[Demethylation of N-methylphenylalkylamines and propylhexedrin as well as of their N-formyl- and formyl)N-methoxymethyl analogues by rat liver homogenates (author's transl)].

The N-demethylation of various secondary N-methylphenylalkylamines and propylhexedrin in the 9.000-g-supernatant of rat liver homogenates is inhibited by introduction of a N-formyl group. Higher reaction rates for the O-methyl derivatives of pholedrin are attributable to an additional O-demethylation which is obviously favoured, when the N-demethylation is inhibited by the formyl group. The velocity of the oxidative degradation of the methoxymethyl group in formyl(N-methoxymethyl) analogues is markedly higher than the N-demethylation rates of the formyl)N-methyl) derivatives and depends to a greater extent upon the structure of the side-chain and the degree of hydrogenation of the nucleus.

Amines↗
PubMed1981

[Metabolic interactions of promethazine (author's transl)].

Owing to enzyme induction, the pretreatment of female Wistar rats with promethazine (Prothazin, Atosil) produces a shortening of the hexobarbital sleeping time, a slight increase in the relative liver weight, an increase in the N-demethylation of aminophenazone, the O-demethylation of codeine phosphate, the O-demethylation of p-nitroanisol, the glucuronidation of p-nitrophenol and the NADPH-cytochrome c reductase activity in the 9.000 g supernatant of liver homogenates. Particularly striking are the strong stimulation of the N-demethylation and the also potentiated [in contrast to the findings obtained with dioxopromethazine (Prothanon)] UDP-glucuronyltransferase activity, whereas the cytochrome P-450 concentration shows a slight trend toward increase, but this is not statistically significant. The findings obtained justify the expectation of drug interactions in case of repeated application of promethazine in the framework of a combined therapy.

Animals↗
PubMed1981

[HPLC of trapidil (Rocornal) and metabolites (author's transl)].

Trapidil (1; Rocornal) and 10 metabolites can be separated by a gradient technique on reversed phases (RP-8 instant columns) using the eluents methanol/water and acetonitrile/phosphate buffer (pH = 5.4); ultraviolet detection. Furthermore, HPLC techniques for purity testing and for determining 1 in serum are described.

Animals↗
PubMed1981

[The synthesis, analysis, stability and biotransformation of N-(3-methylphenyl)-N'-cyanobenzamidine and analogues (author's transl)].

The antivirally active N-(3-methylphenyl)-N'-cyanobenzamidine (1) and some of its analogues were synthetized by the reaction of the ethyl ester of N-cyanobenzimidic acid with the corresponding arylamines. The analytical profile of 1 and of some of its analogues, which is needed for stability and biotransformation studies, was established by means of the following techniques: solubility determination, TLC, UV, IR and MS. When 1 is heated with methanolic HCl and NaOH (0.5 mol/l) for 1 h, several hydrolysis products are formed: m-toluidine, benzoic acid, benzoic acid 3-toluidide, N-(3-methylphenyl)benzamidine, N-(3-methylphenyl)-N'-carboxamidobenzamidine, benzoylurea, However, 1 is fairly stable under physiological conditions so biotransformation studies are not affected. After oral application of 1 to rats, the 3-hydroxymethyl and the 3-methyl-5-hydroxy compound as well as its glucuronide and sulphate conjugate were detected in the urine. The faeces contained considerable amounts of unchanged 1 (incomplete absorption).

Amidines↗
PubMed1980

Stable bone-marrow-derived cell line producing transforming avian acute leukemia virus OK 10.

A stable bone-marrow-derived cell line, OK-BM, producing transforming avian acute leukemia virus OK 10, was established. The cell line has been maintained in culture for over 4 years and 405 passages. The cells grow rapidly in suspension, have a low serum requirement, display a uniform morphology and perpetually release transforming OK 10 virus. No transforming helper virus was detected by interference assay. The cells have a chromosome complement of the chicken. Characterization of the cells indicates that they are of myeloid origin and have properties characteristic of proliferating transformed macrophages.

Animals↗
PubMed1980

[Metabolic interaction of valproic acid (author's transl)].

Valproic acid produces a marked competitive inhibition of the aminophenazone N-demethylation and the codeine phosphate O-demethylation by 9000 g-supernatant of rat liver homogenates, but it exerts virtually no effect on the aniline hydroxylation and the p-nitrophenol glucuronidation which are slightly inhibited only if its tenfold amount is allowed to react on the substrate.

Aminopyrine↗
PubMed1979

[Comparative studies on the stability of aqueous drug solutions in the isothermal and the non-isothermal short-time test as well as in the long-time test. Part 2: The stability of aqueous tetracaine solutions in the non-isothermal short-time test (author's transl)].

A study of the hydrolytic degradation of tetracaine solutions at various pH values demonstrates that the results from non-isothermal stability testing with logarithmic rise in temperature are in good agreement with the activation energies determined, under analogous conditions, by means of the isothermal short-time test and long-time test. The range of the maximum of stability is more clearly evinced by the non-isothermal short-time test than by the isothermal stability test. The comparison of the two methods reveals that the deviation of the reaction rate constants is greater in the non-isothermal test, which is due to the calculation required for the logarithmic rise in temperature. The results obtained with tetracaine evidence that the non-isothermal stability test is an appropriate method for the rapid determination of stability parameters (e.g. stability maximum, hydrolysis velocities) in the frame-work of testing potential drugs for stability and in the optimization of prescriptions.

Chemistry, Pharmaceutical↗
PubMed1979

[Drug interactions].

Explore the source record for details and available documents.

Biological Transport↗