Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study describes: 1. Substrate binding assays investigating the effects of methanolic extracts of unfermented and fermented Rooibos on the binding of natural substrates to ovine adrenal microsomal and mitochondrial P450 enzymes, demonstrating the interference of substrate binding in the presence of the Rooibos extracts. 2. The effects of selected flavonoids (quercetin, rutin and aspalathin) on the binding of natural substrates to ovine adrenal microsomal and mitochondrial P450 enzymes, demonstrating interference of substrate binding in the presence of the flavonoid compounds. 3. Substrate conversion assays in non-steroidogenic COS-1 cells to investigate the effects of methanolic extracts of unfermented and fermented Rooibos on the activity of key steroidogenic P450 enzymes (CYP17A1, CYP21A2, CYP11B1, and CYP11B2), demonstrating inhibition of the catalytic activity in the presence of Rooibos extracts. 4. The effects of selected flavonoids on the substrate conversion of the aforementioned key steroidogenic enzymes expressed in COS-1 cells. 5. An investigation of the effect of methanolic extracts of unfermented and fermented Rooibos on steroid hormone production in human adrenal H295R cells under basal and stimulated conditions, demonstrating the modulating effects of unfermented and fermented Rooibos extracts. Basal and stimulated steroid hormone production was decreased in the presence of unfermented and fermented Rooibos. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf: 1. Die gebruik van substraatbindings-essais om die effek van metanoliese ekstrakte, van gefermenteerde- en ongefermenteerde Rooibos, op die binding van die natuurlike substrate aan skaap adrenale mikrosomale en -mitochondriale P450 ensieme te bepaal. Daar is getoon dat die ekstrakte 'n beduidende inhiberende effek op ensiemsubstraatinteraksie gehad het. 2. Die die inhiberende effek van geselekteerde flavonoïede (kwersetien, rutien and aspalatien) op die binding van die natuurlike substrate aan skaap adrenale mikrosomale en -mitochondriale P450 ensieme. 3. Die gebruik van substraatomsettings-essais in nie-steroïedogeniese COS-1 selle, om die effek van gefermenteerde- en ongefermenteerde Rooibos ekstrakte op die aktiwiteit van die steroïedogeniese P450 ensieme (CYP17A1, CYP21A2, CYP11B1, and CYP11B2) se katalitiese aktiwiteit te bepaal. Daar kon aangetoon word dat die katalitise aktiwiteite van bg. ensieme beduidend beïnvloed word deur die Rooibos ekstrakte. 4. Die gebruik van substraatomsettings-essais in nie-steroïedogeniese COS-1 selle, om die effek van geselekteerde flavonoïede op die aktiwiteit van bogenoemde steroïedogeniese P450 ensieme te bepaal. 5. 'n Ondersoek na die invloed van metanoliese ekstrakte van gefermenteerde- en ongefermenteerde Rooibos op steroïedhormoon biosintese in die menslike adrenale H295R-selmodel. Die ondersoek, onder basale en gestimuleerde toestande, het getoon dat beide Rooibosekstrakte in bogenoemde toestande steroïedhormoon produksie geinhibeer het.

published_or_final_version / abstract / toc / Zoology / Master / Master of Philosophy

published_or_final_version / abstract / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy

by Linda Shiou-mei Ooi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 95-109). / Abstract --- p.i / Acknowledgements --- p.iii / List of Figures --- p.viii / Chapter Chapter I. --- Introduction --- p.1 / Objectives --- p.4 / Chapter Chapter II. --- Literature Review --- p.5 / Chapter II. 1. --- Lipoprotein-Lipids --- p.5 / Chapter II.1.1. --- General Concept and Metabolism of Lipoprotein-lipids --- p.5 / Chapter II. 1.2. --- Factors affecting plasma lipoprotein-lipids --- p.11 / Chapter II. 1.2.1. --- Ageing --- p.11 / Chapter II. 1.2.2. --- Obesity --- p.12 / Chapter II. 1.2.3. --- Diet --- p.13 / Chapter II. 1.2.4. --- Alcohol --- p.13 / Chapter II. 1.2.5. --- Cigarette smoking --- p.14 / Chapter II. 1.2.6. --- Exercise --- p.14 / Chapter II. 1.2.7. --- Gender differences --- p.14 / Chapter II.2. --- Sex Hormones --- p.14 / Chapter II.2.1. --- General concepts of sex hormone-production and the metabolism of sex hormones --- p.15 / Chapter II.2.1.1. --- Biosynthesis of testosterone --- p.16 / Chapter II.2.1.2. --- Metabolism of testosterone --- p.17 / Chapter II.2.1.3. --- Dihydrotestosterone (DHT) --- p.18 / Chapter II.2.1.4. --- Androstenedione --- p.18 / Chapter II.2.1.5. --- Biosynthesis of estrogen in men --- p.18 / Chapter II.2.1.6. --- Metabolism of estrogen --- p.19 / Chapter II.2.2. --- Factors affecting sex hormone levels in plasma --- p.19 / Chapter II.2.2.1. --- Sex hormone binding globulin (SHBG) --- p.19 / Chapter II.2.2.2. --- Sampling time --- p.19 / Chapter II.2.2.3. --- Stress and acute or chronic non-endocrine illnesses --- p.20 / Chapter II.2.2.4. --- Ageing --- p.21 / Chapter II.2.2.5. --- Diet and nutrition --- p.21 / Chapter II.2.2.6. --- "Medication, drugs and alcohol" --- p.22 / Chapter II.2.2.7. --- Body composition and obesity --- p.22 / Chapter II.2.2.8. --- Variations in states of sleep-wake cycle --- p.23 / Chapter II.2.2.9. --- Levels of physical and sympathetic nervous system activity --- p.23 / Chapter II. 3. --- The relationship between sex hormones and lipoproteins --- p.24 / Chapter II.3.1. --- "Gender difference in sex hormones, menopause and lipoprotein-lipids" --- p.24 / Chapter II.3.2. --- "Interventional study, exogenous sex hormone and lipoprotein-lipidsin men" --- p.25 / Chapter II.3.3. --- The relationships of endogenous sex hormones and lipoprotein-lipids --- p.26 / Chapter Chapter III. --- Materials and Methods --- p.28 / Chapter III.l. --- Subjects and Sampling Methods --- p.28 / Chapter III.2. --- Quantitation of serum lipoprotein-lipids --- p.29 / Chapter III.2.1 --- Determination of cholesterol and triglyceride --- p.29 / Chapter Table III.2.1.A. --- Intra-assay variations for cholesterol and triglyceride --- p.30 / Chapter Table III.2.1.B. --- Inter -assay variations for Cholesterol and Triglyceride --- p.30 / Chapter III.2.2. --- Determination of HDL-Cholesterol and its subfractions --- p.31 / Chapter Table III.2.2. --- Intra- and inter-assay variation for HDL-cholesterol --- p.31 / Chapter III.2.3. --- Determination of VLDL-C and LDL-C --- p.32 / Chapter III.2.4. --- Quantitative determination of serum apolipoproteins and Lp(a) --- p.32 / Chapter III.2.4.1. --- Determination of Apolipoproteins A-I and B --- p.33 / Chapter III.2.4.2. --- Determination of Lipoprotein (a) --- p.33 / Chapter III. 3. --- Quantitative determination of sex hormones --- p.33 / Chapter III.3.1. --- For urinary unconjugated and serum total testosterone --- p.34 / Chapter III.3.1.1 --- Experimental Procedures --- p.35 / Determination of the optimal antibody titre --- p.35 / Establishment of a standard curve and quality controls --- p.35 / Preparation of standards --- p.35 / Purification of radioactively-labelled 3H-testosterone --- p.37 / Preparation of charcoal- stripped urine as zero calibrator (blank) --- p.37 / Preparation of spiked urine or plasma --- p.38 / Preparation of samples for RIA --- p.38 / RIA --- p.39 / Calculation --- p.40 / Chapter III.3.1.2. --- Characteristics of the radioimmunoassay for testosterone --- p.40 / Sensitivity --- p.40 / Precision studies --- p.42 / Within- and between- batch imprecisions --- p.42 / Chapter Table III.3.1.2.A. --- Within-run variation --- p.42 / Chapter Table III.3.1.2.B. --- Between-run variation --- p.42 / Recoveries --- p.43 / Chapter Table III.3.1.2.C. --- "The recoveries of known amounts of testosterone added to charcoal-stripped urine, between immunoassays" --- p.43 / Test of linearity --- p.43 / Comparison with another procedure --- p.43 / Cross reactivity of the antiserum --- p.44 / Procedure --- p.46 / Chapter Table III.3.1.2.D. --- Cross reactivity of some naturally occurring steroids with testosterone antiserum --- p.47 / Chapter III.3.2 --- For urinary total testosterone --- p.47 / Test of linearity and recovery --- p.48 / Chapter III.3.3. --- For urinary unconjugated and serum total 17β-Estradiol --- p.50 / Chapter III.3.3.1 --- Experimental procedure --- p.50 / Determination of the optimal antibody titre --- p.50 / Establishment of a standard curve and quality controls --- p.52 / Preparation of standards --- p.52 / Preparation of tracer 3H-estradiol and construction of a standard curve --- p.52 / Preparation of spiked control urine or plasma --- p.52 / Preparation of samples for RIA --- p.53 / Chapter III.3.3.2. --- Characteristics of the radioimmunoassay for E2 --- p.53 / Sensitivity --- p.54 / Precision studies --- p.54 / Within- and between- batch imprecisions --- p.54 / Chapter Table III.3.3.2.A. --- Within-run variation of known amount of E2 added to charcoal- stripped urine --- p.54 / Chapter Table III.3.3.2.B. --- Between-run variation of known amount of e2 added to charcoal- stripped urine --- p.54 / Recoveries --- p.56 / Chapter Table III.3.3.2.C. --- "The recoveries of known amount of e2 added to charcoal- stripped urine, between immunoassays" --- p.56 / Test of linearity --- p.56 / Comparison with another procedure --- p.56 / Chapter III.3.4. --- For urinary total estradiol --- p.58 / Test of linearity and recovery --- p.58 / Chapter III.4. --- Determination of serum sex hormone-binding globulin (SHBG) --- p.60 / Chapter III.5. --- Determination of urinary unconjugated Cortisol --- p.60 / Chapter III.6. --- Statistical methods --- p.62 / Chapter III.6.1. --- Biological Variations --- p.62 / Chapter III.6.2. --- Univariate and multivariate correlations --- p.62 / Chapter Chapter IV. --- Results --- p.64 / Chapter IV. 1. --- The characteristics of the experimental subjects and their lipoprotein-lipids profiles --- p.64 / Chapter Table IV. 1. A. --- The anthropometric and biochemical characteristics of the experimental male subjects --- p.64 / Chapter Table IV.1.B. --- The lipoprotein-lipids profiles in 46 healthy Hong Kong Chinese men --- p.65 / Chapter IV. 2. --- "Levels of sex hormones in serum and urine, and urinary free Cortisol" --- p.65 / Chapter Table IV.2. --- The sex hormones at serum and urinary levels and urinary free Cortisol in 46 healthy Hong Kong Chinese men --- p.66 / Chapter Table IV.2.A. --- Formula for the indirect calculation of unbound (free) testosterone levels in plasma --- p.67 / Chapter Table IV.2.B. --- Formula for the indirect calculation of unbound (free) 17β-estradiol levels in plasma --- p.68 / Chapter IV. 3. --- Biological variations --- p.69 / Chapter Table IV. 3. --- "The biological variations of serum lipoprotein-lipids, serum sex hormones and urinary sex hormones and Cortisol in 46 healthy Hong Kong Chinese men" --- p.69 / Chapter Table IV.3.A. --- Correlations of serum lipoprotein-lipids between short-term (3- week) variations --- p.70 / Chapter Table IV.3.B. --- Correlations of serum and urinary sex hormones and urinary unconjugated Cortisol between short-term (3-week) variations --- p.70 / Chapter IV. 4. --- Univariate correlation --- p.71 / Chapter Table IV.4. --- The univariate correlation table --- p.72 / Chapter IV.4.1. --- Inter-relationship among serum and urinary sex hormones --- p.73 / Chapter IV.4.2. --- Urinary free Cortisol and sex hormones and serum lipoprotein-lipids --- p.73 / Chapter IV.4.3. --- Correlation between urinary sex hormones and serum lipoprotein- lipids --- p.73 / Chapter IV.4.4. --- Correlations among serum lipoprotein-lipids --- p.74 / Chapter IV.4.5. --- Correlations between serum lipoprotein-lipids and sex hormones --- p.74 / Chapter IV.4.6. --- "Correlations between anthropometric variables, sex hormones and lipoprotein-lipids" --- p.75 / Chapter IV.4.7. --- Correlation of the ratio of HDL2 and HDL3 and other variables --- p.76 / Chapter IV. 5. --- Multiple linear stepwise regression --- p.77 / Chapter Table IV.5. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, and Age" --- p.77 / Chapter Table IV.5. A. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, Age, SHBG, and serum and urinary Sex Hormones" --- p.80 / Chapter Table IV.5.B. --- "Stepwise multiple linear regression of lipoprotein-lipids on BMI, W/H Ratio, Age, SHBG, Triglyceride and serum and urinary Sex Hormones" --- p.81 / Chapter Chapter V. --- Discussion --- p.82 / Chapter V. l. --- Experimental subjects and their lipoprotein-lipids profiles --- p.82 / Chapter V. 2. --- Levels of sex hormones in serum and urine --- p.84 / Chapter Table V.2. --- Values of sex steroids in 46 healthy Hong Kong Chinese men compared to others cited in literature --- p.85 / Chapter V. 3. --- "17β-Estradiol,atherogenic lipoprotein-lpids and HDL3" --- p.88 / Chapter V. 4. --- "Testosterone, and HDL-C and its subfractions" --- p.90 / Chapter Chapter VI. --- Conclusions --- p.92 / References --- p.95 / Appendices --- p.110

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

The global population of leatherback sea turtles is decreasing worldwide, with extinction predicted for some populations within 15 years. The population of leatherbacks nesting at Sandy Point National Wildlife Refuge (SPNWR), St. Croix, USVI, displayed a significant population increase from 1982 2001 but has experienced a slowed recovery since then. To better understand the causes of this decline, a historical database of SPNWR nesting female data was utilized to investigate trends in reproductive indices. Since 2001, average remigration interval (RI) has increased significantly, while average number of clutches laid, hatch success, hatchling production, and the percentage of neophytes recruited annually have decreased. Annual remigrant numbers have been stable to increasing, suggesting that adult survivorship remains high. To assess whether maternallyderived factors may be influencing clutch production and low hatch success, blood samples were collected by saturation sampling during nesting. Circulating estradiol, testosterone, and progesterone were evaluated in conjunction with reproductive data. All hormones were highest at deposition of the first clutch and declined progressively with each consecutive clutch, as previously observed in other sea turtle species. Increased clutch production in remigrants was associated with higher estradiol levels compared to neophytes, presumably due to ovarian size and maturity. Contrary to observations in Pacific leatherbacks, progesterone decreased significantly with successive nests and total levels of estrogen were significantly lower, suggesting Atlantic leatherbacks may undergo a longer migration or spend more time in the feeding grounds prior to migrating. Linear Mixed Effect (LME) modeling was employed to determine whether hormone levels at nesting might serve as indicators of reproductive variables. Because models for all hormones were individual specific, a population model could not be developed that effectively utilized hormone levels at nesting to predict clutch size, hatch success, age or RI. However, number of clutches laid may potentially be predicted based on individually tailored estrogen models. Decreased recruitment (due to increased mortality of early life stages, altered sex ratios, or delayed age to sexual maturity), decreased productivity, and increased RI (possibly due to diminished foraging ground productivity) appear primarily responsible for current population trends which threaten the population's future.

Aggression is a feature of many clinical disorders including autism, Alzheimer’s disease, bipolar disorder, and schizophrenia. The available treatment options act to prevent impulsive aggression through modulation of GABAergic and dopaminergic pathways which come with metabolic and dyskinetic side effects. The mechanism underlying aggressive motivation, however, has not been elucidated. In addition, previous studies have been heavily biased towards males of various species. Mimicking changes in day length, or photoperiod, in the laboratory is a natural manipulation used to examine seasonal changes in aggressive behavior in many species. In response to the reduction in the duration of light exposure, animals undergo gonadal regression and become reproductively quiescent. During this non-breeding season in male photoperiod-responsive animals, aggressive behavior increases significantly. Although studies have shown offensive aggression remains elevated in female rodents, seasonal regulation of this behavior in females has not been thoroughly studied. The neuropeptide arginine-vasopressin (AVP) has been implicated in the facilitation of aggressive behavior in male rodents and fishes; therefore, it is useful to examine AVP as a modulator of seasonal aggression in females. Because the actions of AVP in female social behavior may be hormonally-dependent, we investigated the hormonal mechanisms that regulate the expression of AVP receptors and the behavioral actions of AVP on aggression. In addition to changes in gonadal steroid hormones during the non-breeding season, we identified photoperiod-dependent alterations in adrenal hormone secretion as AVP plays a role in regulation of hypothalamic-pituitary-adrenal axis (HPA) activity and anxiety-like behaviors in animal models.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 161-197). Also available in print.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-145).

published_or_final_version / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy