Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 67-69).

Thesis (Ph.D.)--Boston University / The liver has been well established as being one of the most important organs involved in the metabolism of adrenocortical steroids. Liver perfusion, incubations with liver slices, homogenates and purified liver preparations all effect extensive changes on the steroid nucleus. In order to develop a step-wise scheme for the in vitro metabolism of a typical adrenocortical steroid and to localize enzyme systems effecting single metabolic transformations, 11-deoxycortisol was incubated with various rat liver homogenate fractions and the conversion products isolated and identified. The liver fractions were obtained by differential centrifugation of liver homogenates. This procedure afforded a 6000 x g supernatant, a 6000 x g residue (corresponding to mitochondria in sedimentation properties), a 78,000 x g residue (corresponding to microsoaes in sedimentation properties) and a 78.000 x g particulate free supernatant. Each tissue preparation was incubated with 11-deoxycortisol at 37° c. for two hours with flasks open to the atmosphere. A tissue to steroid ratio of approximately 1000:1, based on the initial weight of the liver, was employed [TRUNCATED].

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Trilostane and epostane are synthetic steroids which inhibit the 3beta-hydroxysteroid dehydrogenase enzyme. This enzyme is part of a system which catalyses an essential step in the synthesis of biologically active steroids. In animals and man trilostane preferentially inhibits adrenal steroid synthesis whilst epostane inhibits placental/ovarian steroid synthesis. The synthesis of radiolabelled trilostane and epostane are described. Stability investigations showed these radiolabelled compounds to be susceptible to degradation, although trilostane less so than epostane. Careful handling procedures were essential for metabolism studies. Animal studies showed no difference in the overall excretion and distribution of radioactivity for [[14]Cl-trilostane and [[14]C]-epostane. However the site specific localisation of active components within adrenals and ovaries reflected the in vivo organ selectivity observed for these compounds. In man a major plasma metabolite of trilostane was shown to be 17-ketotrilostane which is intrinsically twice as active as parent compound with regard to 3beta-hydroxysteroid dehydrogenase inhibition. A specific, sensitive and accurate HPLC assay was developed which enabled the measurement of trilostane and 17-ketotrilostane in plasma. Plasma concentrations of 17-ketotrilostane in male volunteers were approximately three-fold higher than trilostane, and consequently this metabolite may be an important contributor to the clinical efficacy of this drug. Micronisation of both trilostane and epostane was shown to be appropriate in order to maximise the oral systemic availability of these compounds. However even with micronised formulations considerable inter-and intra-subject variability was noted. For trilostane, variability in absorption, coupled with individual differences in the metabolism to the more active 17-ketotrilostane, may in part account for the variable efficacy encountered in clinical trials.

A theoretical study of steroidal inhibitors of the enzymes Glucose-6-Phosphate Dehydrogenase and Aromatase is presented. Both enzyme systems are of interest in the study of cancer, the latter being the final step in the biosynthesis of oestrogens which are involved in certain types of breast cancer. Two levels of theory are employed in the study, namely, Ab Initio and Semi Empirical methods. Structures and charges have been calculated using the MOPAC and GAUSSIAN programs and these have been used to model the efficacy of various inhibitors. The major tool in comparing these steroids has been the molecular electrostatic potential (MEP). Maps of the MEP and an analysis of the similarity between the MEP s of different molecules have led both to a method of assessing the activities of steroids as enzyme inhibitors and requirements for the electronic structure of the steroid binding sites within these enzymes. A molecular graphics display program has been developed to facilitate this work. It has been designed to make full use of the facilities available. The quality of the resulting display has improved greatly on what was previously available and has been of value in studies of large molecular systems. The program is written in VAX FORTRAN and uses the Graphics Kernel System (GKS) to produce graphical output and should be reasonably easy to transfer to other systems. Finally, to determine whether PM3 really is a significant advance on AM1, a comparison of the two semi empirical methods is presented. The calculated properties of steroid hormones are compared to those of both Ab Initio calculations and experimental determinations, allowing the quality of the semi empirical predictions to be assessed.

No description available.

Thesis (MTech (Biomedical Technology))--Cape Technikon, Cape Town,1997 / The aims of this study were to measure: 1. Myometrial cells of menopausal uteri to establish whether they atrophy after the menopause. 2. Myometrial cells at different phases of the menstrual cycle to investigate the influences of oestrogen and progesterone during the cycle. 3. Myometrial cells in the fundus and lower uterine segment to establish whether they differ in size. 4. Myometrial cells of pregnant uteri to investigate the effect of the hormonal status of pregnant women on the size of myometrial cells. 5. Neoplastic cells of leiomyomas of the uterus to investigate whether these benign tumours behave in the same manner as myometrium or, because they are neoplastic, they react differently. A preliminary investigation was undertaken to establish the optimal methodology for this study to measure myometrial and leiomyoma nuclei in the uterus. The aims of this preliminary investigation were: 1. To test the reproducibility of measurements of myometrial and leiomyoma nuclei in transverse and cross section. 2. To test five histological staining methods to ascertain the best method for a morphometric study on uterine cells. 3. To find the minimum sample size of nuclei per section of myometrium or leiomyoma in order to yield statistically significant results. This preliminary study found that the Haematoxylin and Eosin stain gave the most statistically reproducible measurements. Subjective assessment of the five staining methods also found Haematoxylin and Eosin to be optimal. It was also found during the preliminary study that measuring the myometrial nuclei in cross rather than transverse section gave the most statistically reproducible measurements. It was also found that it was best to use an axial ratio criterion of 0,9 when measuring cross-sectioned myometrial nuclei. The optimum sample size per section was also investigated and it was found that measuring 100 nuclei was optimal. It was found that in the uteri used in this study there was no statistically significant decrease in nuclear size after the menopause. It was also found that there was no statistically significant difference in nuclear size during the different phases of the menstrual cycle. There was also no notable difference in nuclear size between nuclei in the fundus and lower segment of the uteri in this study. It was found that there was a significant increase in the size of nuclei in leiomyomas compared to the normal myometrial nuclei from the same patient. The myometrial nuclei from pregnant uteri were also significantly larger than those from non-gravid uteri.

Abstract 17β-Hydroxysteroid dehydrogenases (17HSDs) catalyze the reactions between 17-hydroxy and 17-keto steroids. In the present study, the enzyme activities and tissue distribution of 17HSD type 1, type 2 and type 4 were characterized. Furthermore, the role of 17HSD type 1 in estrogen-dependent growth was studied in MCF-7 breast cancer cells which were stably transfected with type 1 cDNA. Endogenous oxidative 17HSD activity found in COS-m6 monkey kidney cells was first compared with that of human placental 17HSD. Cultured COS-m6 cells exclusively possessed oxidative 17HSD activity, converting estradiol (E2) to less active estrone (E1). When placental 17HSD was transfected into these cells, highly reductive activity appeared. The 17HSD enzyme in COS-m6 cells also catalyzed the conversion of testosterone to androstenedione, whereas the placental enzyme was estrogen-specific. These results further proved the existence of different 17HSD isoenzymes. The enzymatic properties and cell- and tissue-specific expression of 17HSD type 1, type 2 and oxidative type 4 were further characterized. The data confirmed that in cultured cells the direction of 17HSD activity is determined by the expression of different isoenzymes and not by the intracellular environment. In addition, the 17HSD type 1 gene expresses two mRNA signals, 1.3 kb and 2.3 kb in size. The expression of 1.3 kb mRNA, but not 2.3 kb mRNA was related to enzyme concentration in all the cell types studied. The type 1 enzyme was expressed in the placenta, ovary and in some breast cancer specimens and in the cell lines originated from these tissues. 17HSD type 2 was more widely expressed in both steroidogenic and in target tissues of steroid action. 17HSD type 4 was expressed in almost all cell lines and in all tissues studied, but no correlation with 17HSD activity was detected. These results suggest that 17HSD type 1 is involved in E2 production in females and 17HSD type 2 is responsible for inactivation of sex steroids. However, the oxidation of 17β-hydroxysteroids seems not to be the primary activity of 17HSD type 4. The mRNAs for 17HSD type 1, type 2 and type 4 were found to be expressed in human mammary epithelial cells. In breast tissue samples both 17HSD type 1 and type 2 were detected by in situ hybridization. Despite the presence of 17HSD type 1 mRNA in human mammary epithelial cells, only oxidative 17HSD activity was detected. The reason for the lack of reductive activity is not yet known. Finally, MCF-7 breast cancer cells were stably transfected with 17HSD type 1 cDNA in order to study the effect of 17HSD type 1 on estrogen-dependent growth. In wild type MCF-7 cells, very low 17HSD activity was detected and E1 did not have any effect on cell growth. In the cells expressing 17HSD type 1, E1 was rapidly converted to E2. Hence in these cells E1 had a similar growth-promoting effect as E2 as a result of the action of 17HSD type 1. The presence of 17HSD type 1 in breast cancer cells may thus be an important factor regulating estrogen exposure and the estrogen-responsive growth of breast cancer tissue.

It has been recorded that women respond to tricyclic antidepressives with a greater incidence of anticholinergic side effects than men do, particularly women taking an exogenous source of oestrogen. The aim of this study was to investigate the influence that ethinyl oestradiol and Premarin© had on the metabolism of a number of tricyclic antidepressives, and also the influence they had on the binding ability of microsomes to imipramine. Rat hepatocyctes and microsomes were used. Detection techniques used were High Pressure Liquid Chromatography and Spectrophotometry respectively. In addition to these studies, a study of the anticholinergic activity of Nomifensine, tricyclic antidepressives and their derivatives was performed on a rat jujenum. Results conclusively showed that ethinyl oestradiol had a marked influence on the metabolism of the tricyclic antidepressives studied. Premarin© had Iittle, if any influence. However, both ethinyl oestradiol and Premarin© affected the binding of microsomes to imipramine, but ethinyl oestradiol had the greater effect. The parent compound in each case exhibited a higher pAZ value. Results indicate that a possible explanation for the increased anticholinergic side effect is due to an inhibition of the metabolism of the tricyclic antidepressives by oestrogen.

No description available.