A species comparison of 2,4-dinitrotoluene metabolism in vitro

Summary Postmitochondrial supernatants prepared from livers of mice, rats, rabbits, dogs, and monkeys metabolized 2,4-dinitrotoluene. The pattern of metabolites was characterized in both sexes of the species examined. In addition, the pattern of metabolites was altered by varying incubation conditions and pretreating male rats with phenobarbital or SKF 525-A.This research was supported by the US Army Medical Research and Development Command, Fort Detrick, Frederick, Maryland 21701, under Contract No. DAMD-17-74-C-4073. The authors thank Ms Mary Sawyer for competent technical assistance.     

A comparison of the effect of potassium ions on the metabolism of retina and brain cortex slicesin vitro

Zusammenfassung Der Einfluss einer erhöhten Kalium-Ionenkonzentration auf denin vitro-Metabolismus von Schweine-Retina und Gehirnrindenschnitten des Meerschweinchens wird verglichen. Die höhere Kalium-Ionenkonzentration im Medium bewirkt im ersten Falle eine Verminderung, im zweiten dagegen eine Steigerung von Sauerstoffaufnahme und anaerober Milchsäurebildung. Bei beiden Geweben wird durch die vermehrte Kalium-Ionenkonzentration die Bildung von Ammoniak gehemmt.     

Steroid metabolism by mouse preimplantation embryos in vitro.

Mouse preimplantation embryos were incubated with radioactive pregnenolone, progesterone or dehydroepiandrosterone for various periods of time. These substrates were not converted to metabolites even after incubation of 120 h. We suggest that preimplantation mouse embryo does not possess enzyme activities for steroid metabolism.     

Testosterone metabolism by mouse placenta in vitro

Zusammenfassung 4-C¹⁴-Testosteron wurde durch Mäuseplazenta in vitro zu Steroiden umgesetzt: 3-Hydroxy-5-androstan-3, 17-dion, 3-Hydroxy-5-androstan-3, 17-dion, 4-Androsten-3, 17-dion und 5-Androstan-3, 17-dion. Eine Umsetzung von Testosteron zu Östrogenen wurde nicht nachgewiesen.     

A comparison of cycloartenol and lanosterol biosynthesis and metabolism by the Oomycetes

Summary Representative members in each of the four orders of Oomycetes (Phytophthora cactorum, Peronosporales;Lagenidium callinectes, L. giganteum, Lagenidiales;Saprolegnia ferax, Saprolegniales;Apodachylella completa, Leptomitales) have been examined for their ability to synthesize and polycyclize squalene-oxide (SO) to a tetracyclic product and to differentiate between cycloartenol and lanosterol metabolism to sterols.P. cactorum andL. giganteum failed to synthesize or metabolize SO, cycloartenol or lanosterol. While the other three fungi synthesized sterols via SO and lanosterol, a minor metabolism of added cycloartenol to the 4,4-desmethyl-14-methylcyclosteroid dehydropollinastanol was observed.Acknowledgment.Saprolegnia ferax-ATCC 3605 (1),Lagenidium callinectes ATCC 24973 (2),Apodachlyella completa (3) were obtained from Dr J. Aronson, Arizona State Univ. (3),Lagenidium gigateum was obtained from a drainage ditch in California (4), andPhytophthora cactorum was obtained from the U.C. Berkeley Fungal Collection (5). The fungi were cultured as previously described: Cultures 1,2,3: Berg, L. B., Ph. D. dissertation, Univ. of MD., College Park (1983); culture 4: Kerwin, J.L., and Washino, R.K., Exp. Mycol.7 (1983) 109; culture 5: Nes, W.D., and Stafford, A.E., Lipids19 (1984) 544. Preliminary observations involving the labeled substrates were presented by Le, P.H., Nes, W.D., and Parish, E.J. J. Am. Oil Chem. Soc.62 (1985) 655(A). Please address all correspondence to W.D. Nes, Plant Physiology and Chemistry Research Unit, ARS-US Dept of Agriculture, Berkeley, CA 94710, USA.     

Steroid metabolism by mouse preimplantation embryos in vitro

Summary Mouse preimplantation embryos were incubated with radioactive pregnenolone, progesterone or dehydroepiandrosterone for various periods of time. These substrates were not converted to metabolites even after incubation of 120 h. We suggest that preimplantation mouse embryo does not possess enzyme activities for steroid metabolism.Acknowledgments. The authors would like to thank Prof. L. Saxén for giving the animals and the facilities of his tissue culture laboratory.     

Progesterone formation and metabolism by rabbit placenta in vitro

4-¹⁴C-Progesterone and 4-¹⁴C-pregnenolone are metabolized in vitro by rabbit placenta, at day 15 and 28 of gestation, exclusively to compounds reduced in ring A (5) and at carbon 3 and 20.     

Thein vitro inhibition of pentobarbital metabolism by chlorpromazine

Riassunto Si è osservato che il pentobarbital alla concentrazione di 2 × 10^–4 M può inibire per il 44% il metabolismoin vitro della cloropromazina alla medesima concentrazione.Si è discussa quindi la possibilità di inibire il metabolismoin vitro di alcuni farmaci propria di altre sostanze che vengono metabolizzate in maniera del tutto simile da sistemi enzimatici a livello microsomale epatico.     

In vitro metabolism of ethionine, N-acetyl-ethionine and N-acetylmethionine by rat liver microsomes.

Rat liver microsomes deacetylated N-acetylethionine and N-acetyl-methionine to ethionine and methionine. The deacetylation of N-acetylmethionine was more rapid than the deacetylation of N-acetylethionine. Ethionine was slowly converted to ethionine sulfoxide by the microsomal preparations. N-Acetylethionine and N-acetylmethionine were not oxidized by the microsomes.     

Electrical response of bat retina to spectral stimulation: comparison of four microhiropteran species.

Electrical responses of the retinas of 4 species of microchiropteran bats stimulated by spectrally restricted light flashes were found to diverge systematically from the rhodopsin absorption spectrum. The divergence was progressively greater across the 4 species. The results appeared explainable by assuming a second photoreceptor class and photopigment which was present in progressively greater numbers in the retinas of Eptesicus fuscus, Desmodus rotundus, Artibeus jamaicensis and Carollia perspicillata.     

A comparison of the effects of the optical isomers of isoproterenol on energy metabolism in a mouse sarcoma

Summary Disturbance to energy production in the S180 sarcoma (CB) by optical isomers of isoproterenol was assessed from altered adenine nucleotide levels at 1 h. The L-isomer almost halved the ATP level and lowered the energy charge significantly; the D-isomer was inactive. Dependence of tumor injury on cytochrome P-450 activity appears unlikely.One of us (GRNJ) thanks the Department of Surgery, Medical School, Kings's College Hospital, London, England, for the provision of experimental facilities; the Institute of Biochemistry, German Cancer Research Centre, Heidelberg, FRG, for permitting the measurement of metabolites; the Cancer Research Campaign, London, UK, for a part-time grant; and Zyma GmbH, München, FRG, and the estate of the late Dr Lucie Polak for additional financial support.     

A comparison of the effects of the optical isomers of isoproterenol on energy metabolism in a mouse sarcoma

Disturbance to energy production in the S180 sarcoma (CB) by optical isomers of isoproterenol was assessed from altered adenine nucleotide levels at 1 h. The L-isomer almost halved the ATP level and lowered the energy charge significantly; the D-isomer was inactive. Dependence of tumor injury on cytochrome P-450 activity appears unlikely.     

Lead metabolism in lactation.

A 2-fold increase in lead absorption was observed in lactating animals which received 2 mg Pb/l in drinking water. About one-half of the absorbed lead was transferred to the litters.     

An in vitro method for studying the metabolism of young bone matrix]

A method for studying in vitro bone resorption by the use of 35S labeled injection was investigated. Various substances (papaine) and hormones (calcitonin, vitamin D analogues) were tested and their effects on 35S and 45Ca metabolism were compared.