The sexually differentiated metabolism of [6,7-3H]17 beta-oestradiol in rats: male-specific 15 alpha- and male-selective 16 alpha-hydroxylation and female-selective catechol formation.

The oxygenated-metabolite profiles of exogenous 17 beta-oestradiol (E2) in adult male and female Wistar rats have been characterized and major sex-dependent biotransformations observed which correlate with the regioselectivities of known sexually differentiated hepatic P450. [6,7-3H]E2 (27 micrograms/kg) was given i.v. The metabolites of E2 were rapidly and extensively excreted in bile (46 and 78% of the dose over 1 and 6 h, respectively). Female rats metabolized E2 by one major pathway: oxidation to oestrone (E1) followed by C-2 hydroxylation and O-methylation; the principal aglycones (0-1 h bile collections) were E1 (14%), 2-hydroxyE1 (2-OHE1) (42%) and 2-methoxyE1 (24%). Male rats metabolized E2 principally by two parallel composite pathways of E1 hydroxylation which yielded a complex mixture of mono- and di-oxygenated compounds: 15 alpha-OHE1 (33%), 2,15 alpha-diOHE1 (7%), and 2-methoxy-15 alpha OHE1 (14%); 16 alpha-OHE1 (13%), 2,16 alpha-diOHE1 (4%) and 2-methoxy-16 alpha-OHE1 (2%). 15 alpha-Hydroxylation was unique to males. The balance of aromatic and alkyl hydroxylation in males was dose-dependent: at 3 mg/kg, 15 alpha-hydroxylation was decreased approx. 50% in favour of 2-hydroxylation whilst 16 alpha-hydroxylation was largely unaffected. The male-specific 15 alpha-hydroxylation and male-predominant 16 alpha-hydroxylation of E1 derived from E2 in vivo may be ascribable to the male-specific isoforms P450IIC13 and P450IIC11, respectively.     

Analysis of a continuous, aerobic, fixed-film bioreactor. I. Steady-state behavior

The analysis of a continuous, aerobic, fixed-film bioreactor is performed by simulating the behavior of penicillin production in a three-phase fluidized bed. Rigorous mathematical models are developed for a fluidized-bed fermentor in which bioparticles are fluidized by the liquid medium and air. The steady-state performance of the fluidized-bed reactor is appraised in terms of penicillin productivity and outlet concentration by considering the two extremes in contacting patterns, complete back-mix and plug flow, in the absence of a growing biofilm. The results show that the complete back-mix contacting pattern is preferred over that of plug flow due to the nature of the penicillin kinetic relationships. It is also shown that for the dual-nutrient (glucose and oxygen) penicillin reaction system the optimum biofilm thickness does not equal the penetration depth of a limiting nutrient, but depends upon the total reactor configuration.     

Drug protein conjugates--III. Inhibition of the irreversible binding of ethinylestradiol to rat liver microsomal protein by mixed-function oxidase inhibitors, ascorbic acid and thiols

The metabolism of [6,7-3H]ethinylestradiol [( 3H]EE2) by rat liver microsomes was studied in vitro. After incubation of [3H]EE2 with rat liver microsomes for 20 min, 90% of the substrate was metabolised and 18% of the 3H-labelled material irreversibly bound to microsomal protein. Ascorbic acid (1 mM) decreased irreversible binding of 3H and produced an accumulation of 2-hydroxyethinylestradiol (2OH-EE2), while mixed-function oxidase inhibitors (0.5 mM) decreased binding of 3H to protein by inhibiting EE2 2-hydroxylation. Addition of thiols gave water-soluble metabolites which were characterised as 1(4)-thioether derivatives of 2OH-EE2 by co-chromatography with synthetic products. The results are consistent with the hypothesis that the chemically reactive metabolite of EE2 formed in vitro is either a quinone or o-semiquinone derived from 2OH-EE2 [1].     

Sporophore production ofAgaricus bisporus in aseptic environments

Production of mature sporophores ofAgaricus bisporus was achieved for the first time in amended, autoclaved soil, gamma-sterilized soil, and soil-extract agar medium. The initiation of sporophores was triggered by metabolites of soil-inhabiting bacteria, particularly nodule forming isolates. Whether a single metabolite or several metabolites of these bacteria caused formation of sporophores could not be established; however, biotin alone when added to soil extract medium produced comparable results. The potentiality of different bacteria to induce sporophore formation varied considerably within species and isolates.Amino acids favored vegetative growth ofA. bisporus, but failed to induce formation of sporophores. Organic acids supported luxuriant growth and poor sporophore formation. Among several growth-promoting substances and vitamins, biotin induced abundant formation of mature sporophores.The authors are thankful to Dr. C. Corke, Department of Soil Microbiology, University of Guelph, Ontario, for providing some bacterial cultures used in this study.     

The essential role of hypusine in eukaryotic translation initiation factor 4D (eIF-4D). Purification of eIF-4D and its precursors and comparison of their activities

Eukaryotic translation initiation factor 4D (eIF-4D) is the only protein known to contain the amino acid, hypusine [N epsilon-(4-amino-2-hydroxybutyl)lysine]. This unusual amino acid is formed post-translationally by modification of a single specific lysine residue in an eIF-4D precursor protein. Two separate eIF-4D precursors, each of which contains a lysine residue in place of the hypusine residue and each of which thereby serves as a protein substrate for the hypusine modification, were purified from DL-2-difluoromethylornithine-treated Chinese hamster ovary cells by means of a five-step procedure. These two precursors termed PI and PII both have apparent molecular masses of approximately 17 kDa, indistinguishable from that of eIF-4D, but exhibit more acidic isoelectric points (5.1 and 5.25 for PI and PII, respectively, compared with 5.37 for eIF-4D). These physical characteristics, together with other properties, indicate that eIF-4D differs from PII only in possessing the hypusine residue in place of a lysine residue, whereas an additional structural difference exists between PI and eIF-4D. eIF-4D from CHO cells provides a significant enhancement of methionyl-puromycin synthesis, a model assay for translation initiation. Neither PI nor PII stimulates this in vitro system. These findings are the first direct evidence that hypusine is essential for the biological activity of eIF-4D.     

Immobilization ofColeus blumei cells in a column reactor using a spray feeding system

Summary Coleus blumei cells were immobilized in a column reactor packed withLuffa cylindrica pieces. Medium was fed from the top of the column using a spray system and cells maintained high viability for 52 days. Cell growth was slower but rosmarinic acid production was better compared to immobilized cells in the shake flasks.