Human (h) growth hormone (GH) levels decline rapidly in response to excess caloric intake before there is any evidence of obesity. In this thesis, the mechanism underlying this response was examined by manipulating levels of caloric intake and physical activity at the levels of gene expression and chromosomal structure. Transgenic mice containing the intact hGH locus were used as a model system. Briefly, the findings are: (I) High caloric intake (high fat diet) for three days resulted in hyperinsulinemia and a decrease in both hGH synthesis and secretion. (II) Incorporation of physical activity (swim) muted the effects of excess caloric intake on insulin levels as well as hGH production. (III) Human GH RNA accumulation was shown for the first time to be negatively regulated by insulin in pituitary cultures, and (IV) an enhancer box (E-box) DNA element was implicated in this response. (V) Induction of the E-box associated transcription factor HIF-1α with insulin significantly decreased hGH RNA levels, and was accompanied by recruitment of HIF-1α to the hGH gene (hGH) promoter in situ. (VI) Both a reduction in HIF-1α synthesis and HIF-1 DNA binding blunted the negative effect of insulin on hGH RNA levels. (VII) The hGH response to insulin was associated with a decrease in histone H3/H4 hyperacetylation in the proximal hGH promoter region. The same pattern of chromatin remodelling was observed in pituitary cells in vivo in response to excess caloric intake. (IX) Increased recruitment of nuclear receptor co-repressor and decreased association of RNA polymerase II were also observed. Collectively, these effects are consistent with reduced hGH promoter function. (X) This reduction by excess caloric intake was also consistent with changes in the three dimensional-structure of the hGH locus including detected loss of physical interaction between hGH enhancer and promoter regions. (XI) By contrast, physical activity combined with the high caloric intake preserved the chromosomal structure of the hGH locus. These observations are discussed in relation to a physiological requirement for rapid control of hGH levels in response to energy homeostasis, as well as the molecular basis governing this process. / May 2015

The purpose of this study was to investigate endocrine responses to redistribution with heavier loads (RR+L) during back squat (BS) exercise in resistance-trained men. Ten men (mean±SE; 23±2 years, 175.6±2.0 cm, 78.0±3.4 kg, 4±1 training years) were assigned using randomization to either RR+L (4 sets of (2×5 repetitions) of BS with 30 s intra-set and 90 s inter-set rest using 75% of their 1RM) or traditional sets (TS; 4 sets of 10 repetitions of BS with 120 s inter-set rest using 70% of their 1RM). Fasted blood samples were collected pre-exercise (PRE), immediately post-exercise (IP), and 5 (+5), 15 (+15), and 30 (+30) minutes post-exercise to analyze the concentrations of testosterone (T), growth hormone (GH), cortisol (C), and blood lactate (BL). Two-way ANOVAs with repeated measures were used (p≤0.05). A main effect of condition (p=0.023) was observed for BL (RR+L; 5.9±0.5 vs TS; 6.7±0.4 mmol/L). A main effect of time point (p≤0.001) was observed for T, GH, C, and BL. T was greater at IP (8.8±1.1), +5 (9.0±1.1), +15 (8.5±1.0), and +30 (8.0±1.0) than PRE (7.1±0.8 ng/mL). GH was greater at IP (58.3±12.7), +5 (62.8±12.7), +15 (67.9±13.3), and +30 (52.8±11.2) than PRE (3.6±1.6 µIU/mL). C was greater at +15 (25.5±2.9) and +30 (25.6±2.7) than PRE (20.0±2.7 µg/dL). BL was greater at IP (8.6±0.6), +5 (8.2±0.6), +15 (7.4±0.5), and +30 (5.8±0.5) than PRE (1.4±0.2 mmol/L). RR+L resulted in lower BL but no differences in T, GH, and C responses compared to TS. Thus, practitioners may incorporate RR+L without affecting endocrine responses.

No study has examined the effect of exercise modality (free weight vs. machine weight) on the acute hormonal response using similar multi-joint exercises. The purpose of this investigation was to examine the effect of resistance exercise modality on acute hormonal responses by comparing the squat and leg press which are multi-joint, and similar in action and lower-body muscle involvement. Ten resistance trained men (21-31 y, 24.7 ± 2.9 y, 179 ± 7 cm, 84.2 ± 10.5 kg) participated in the study. Sessions 1 and 2 determined the participants’ 1-RM in the squat and leg press. During acute heavy resistance exercise testing visits (AHRET), sessions 3 and 4, participants completed 6 sets of 10 repetitions with an initial intensity of 80% of their 1-RM for the squat and leg press exercises. There was a 2 minute rest period between each set. Blood samples were collected before, immediately after, and 15 and 30 minutes after exercise via intravenous catheter during the AHRET visits and were analyzed for testosterone, cortisol, and growth hormone. Lactate, plasma volume change, heart rates and ratings of perceived exertion were also measured. Total work was calculated for external load only and for external load and the body mass used in the exercises. The 4 sessions were counterbalanced and randomized for exercise mode. Testosterone for the squat (Pre: 23.9 ± 8.7 nmol•L-1; IP: 31.4 ± 10.3 nmol•L) and leg press (Pre: 22.1 ± 9.4 nmol•L-1; IP: 26.9 ± 7.8 nmol•L) increased but more significantly after the squat. Growth hormone increased in both the squat (Pre: 0.2 ± 0.2 µg/L; IP: 9.5 ± 7.3 µg/L) and the leg press (Pre: 0.3 ± 0.5 µg/L; IP: 2.8 ± 3.2 µg/L). The increase was significantly higher after the squat compared to the leg press. Cortisol also increased after performing the squat (Pre: 471.9 ± 167.2 nmol•L-1; IP: 603.2 ± 277.6 nmol•L) and leg press (Pre: 463.5 ± 212.4 nmol•L-1; IP: 520.3 ± 270.3 nmol•L), but there was no significant difference between the two modes. The total work was significantly higher in the squat (60509 ± 10759 j) compared to the leg press (42875 ± 7010). The squat exercise is more effective at inducing an acute hormonal response. If the leg press exercise is used, the hormonal response may be reduced, which might lead to reduced training adaptations, especially when only a 90º knee angle ROM is used. To induce the maximal hormonal response to resistance exercise, free weight exercises should be used.

O objetivo deste estudo foi identificar SNPs na região promotora e no intron I do gene GH (região alvo) e verificar sua possível associação com o crescimento de O. niloticus, o que foi executado em duas etapas: (1) prospecção de SNPs; (2) associação de SNPs com crescimento das variedades Red-Stirling e Chitralada. As análises de associação foram realizadas por meio de metodologia estatística baseada em análise univariada de modelo linear misto considerando-se efeitos fixos e aleatórios. Nove SNPs foram identificados no promotor (GHP1 a GHP9) e um na região 5 UTR (GHP10), os quais formaram 10 blocos genotípicos (A a J). Na população de associação seis novos blocos foram identificados (K a P). Os blocos B, P, K, L e M foram associados aos melhores pesos e os SNPs GHP6 a GHP10 demonstraram associação significativa (P < 0,05) como o crescimento. Portanto, foi possível estimar um conjunto de genótipos com maior efeito genético aditivo sobre o crescimento, o qual poderia ser utilizado em futuros programas de melhoramento genético assistidos por marcadores moleculares. / The present study aimed to identify SNPs in the proximal promoter region and in the first intron of GH gene and to evaluate if there is association of SNPs variation with the O. niloticus growth rate. Firstly, SNP searching in the two targeted regions was carried out in four strains. Then, two strains, Red-Stirling and Chitralada were used in grow-out testing in cages. Association between SNPs and growth rate were statistically estimated by univariate linear mixed model taking into account fixed and random effects. Nine SNPs were found in the proximal promoter region and one in the 5 UTR region, which formed 10 genotype blocks (A to J). Five of these genotype blocks (F to J) were not found in the grow-out individuals. However, six new genotype blocks (K to P) were identified. Genotype blocks B, P, K, L and M were statistically associated to the best weights, and the SNPs GHP6 to GHP10 individually showed significant association (P < 0,05) with growth. These findings found herein may potentially be used as Marked-Assisted Selection in tilapia breeding programs.

Chan, Yuk-Hang. / "June 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 162-190). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Yu, Man Ying Susana. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 103-117). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Table of contents --- p.viii / Symbols and abbreviations --- p.xii / Scientific names --- p.xiv / List of figures --- p.xv / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Structure of ovarian follicles --- p.1 / Chapter 1.2 --- Regulation of ovarian follicle development --- p.3 / Chapter 1.2.1 --- Endocrine regulation --- p.3 / Chapter 1.2.1.1 --- Gonadotropins- FSH and LH --- p.3 / Chapter 1.2.1.2 --- Co-gonadotropin- growth hormone --- p.5 / Chapter 1.2.2. --- Paracrine regulation --- p.6 / Chapter 1.2.2.1 --- Activin --- p.6 / Chapter 1.2.2.2 --- Insulin-like growth factor I (IGF-I) --- p.7 / Chapter 1.3 --- The GH-IGF-I axis --- p.7 / Chapter 1.3.1 --- The somatomedin hypothesis --- p.8 / Chapter 1.3.2 --- "Structure and signaling of GH, GHR" --- p.8 / Chapter 1.3.3 --- Structure and signaling of IGF system --- p.9 / Chapter 1.3.4 --- Role of GH-IGF system in reproduction --- p.11 / Chapter 1.3.5 --- GH action in ovarian functions --- p.12 / Chapter 1.3.6 --- IGF-I action in ovarian functions --- p.13 / Chapter 1.3.7 --- The mini GH-IGF axis within the ovary --- p.14 / Chapter 1.4 --- Objectives of present study --- p.14 / Chapter Chapter 2 --- "Expression Profiles of the GH-IGF System in the Ovary of Zebrafish, Danio rerio" --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Material and Methods --- p.21 / Chapter 2.2.1 --- Animals --- p.21 / Chapter 2.2.2 --- Isolation of tissues and different stages of follicles from the zebrafish --- p.22 / Chapter 2.2.3 --- Separation of somatic follicle layers and oocytes --- p.22 / Chapter 2.2.4 --- Primary follicle cell culture --- p.22 / Chapter 2.2.5 --- Total RNA extraction --- p.23 / Chapter 2.2.6 --- Reverse transcription --- p.23 / Chapter 2.2.7 --- "Validation of semi-quantitative RT-PCR assays for GH (gh), GHR (ghr), IGF-I (igf1), IGF-II (igf2), and IGF-I receptor (igf1r)" --- p.24 / Chapter 2.2.8 --- Data analysis --- p.25 / Chapter 2.3 --- Results --- p.25 / Chapter 2.3.1 --- Validation of semi-quantitative RT-PCR assays --- p.25 / Chapter 2.3.2 --- Spatial expression of GH-IGF in different tissues of zebrafish --- p.26 / Chapter 2.3.3 --- "Localization of gh, ghr, igf1, igf2 and igf1r within the zebrafish follicle" --- p.26 / Chapter 2.3.4 --- Temporal expression profiles of GH-IGF system during folliculogenesis --- p.28 / Chapter 2.4 --- Discussion --- p.28 / Chapter Chapter 3 --- Regulation of the GH-IGF-I System and Its Cross-talk with the Activin System in the Zebrafish Ovary --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.2 --- Material and methods --- p.45 / Chapter 3.2.1 --- Animals --- p.45 / Chapter 3.2.2 --- Chemicals and hormones --- p.45 / Chapter 3.2.3 --- Primary follicle cell culture --- p.45 / Chapter 3.2.4 --- Preparation of ovarian fragments --- p.45 / Chapter 3.2.5 --- Total RNA extraction --- p.45 / Chapter 3.2.6 --- RT-PCR --- p.47 / Chapter 3.2.7 --- Construction of real-time PCR standards --- p.47 / Chapter 3.2.8 --- Real-time PCR and semi-quantitative RT-PCR --- p.48 / Chapter 3.2.9 --- Data analysis --- p.49 / Chapter 3.3 --- Results --- p.49 / Chapter 3.3.1 --- "Expression of growth hormone (gh), growth hormone receptors (ghr1 and ghr2\ IGF-I (igf1), IGF-II (igf2), IGF-I receptor (igf1ra and igf1rb), activin subunits (inhba and inhbb) and follistatin (fst) in cultured zebrafish ovarian fragments" --- p.49 / Chapter 3.3.2 --- "Establishment of real-time RT-PCR for zebrafish inhba, inhbb and bactin" --- p.50 / Chapter 3.3.3 --- GH regulation of activin expression in cultured zebrafish follicle cells --- p.50 / Chapter 3.3.4 --- GH regulation of IGF-I in cultured zebrafish follicle cells --- p.51 / Chapter 3.3.5 --- IGF-I regulation of activin expression in cultured zebrafish follicle cells --- p.51 / Chapter 3.3.6 --- Activin regulation of IGF system --- p.52 / Chapter 3.4 --- Discussion --- p.52 / Chapter Chapter 4 --- Production of recombinant zebrafish growth hormone --- p.69 / Chapter 4.1 --- Introduction --- p.69 / Chapter 4.2 --- Material and Methods --- p.71 / Chapter 4.2.1 --- Animals --- p.71 / Chapter 4.2.2 --- Construction of expression plasmids pPIC9K/zfGH --- p.71 / Chapter 4.2.3 --- Production of recombinant zebrafish GH using Pichia pastoris --- p.73 / Chapter 4.2.4 --- SDS-PAGE and silver staining --- p.74 / Chapter 4.2.5 --- Purification --- p.74 / Chapter 4.2.6 --- Primary follicle cell culture --- p.75 / Chapter 4.2.7 --- Zebrafish hepatic cell culture --- p.76 / Chapter 4.2.8 --- RNA extraction and RT-PCR --- p.76 / Chapter 4.2.9 --- Real-time PCR --- p.77 / Chapter 4.2.10 --- Cell culture and transient transfection --- p.78 / Chapter 4.2.11 --- Luciferase reporter gene assay --- p.78 / Chapter 4.2.12 --- Data analysis --- p.79 / Chapter 4.3 --- Results --- p.79 / Chapter 4.3.1 --- Production of recombinant zebrafish GH --- p.79 / Chapter 4.3.2 --- Effect of recombiant zfGH on the expression of activin β Aand βB in cultured zebrafish follicle cells --- p.80 / Chapter 4.3.3 --- Effect of zfGH on the expression of igf1 in cultured zebrafish hepatic cells --- p.80 / Chapter 4.3.4 --- Luciferase reporter gene assay --- p.81 / Chapter 4.4 --- Discussion --- p.81 / Chapter Chapter 5 --- General Discussion --- p.94 / Chapter 5.1 --- Overview --- p.94 / Chapter 5.2 --- Major achievements of the present study --- p.95 / Chapter 5.2.1 --- Demonstration of a local mini-GH-IGF-I axis within the zebrafish ovary --- p.96 / Chapter 5.2.2 --- Differential expression profiles of the GH-IGF system during folliculogenesis --- p.96 / Chapter 5.2.3 --- The inter-relationship of GH-IGF and activin-follistatin systems --- p.96 / Chapter 5.2.4 --- Production of recombinant zebrafish GH --- p.97 / Chapter 5.3 --- Future prospects --- p.97 / References --- p.102 / Symbols and Abbreviations / Symbols / α Alpha / β Beta / Abbreviations / 20β-HSD 20β-hydroxysteroid dehydrogenase / bp Base pair / cAMP Cyclic adenosine monophosphate / cDNA Complementary cDNA / CHO Chinese hamster ovary / "DHP 17α, 20β-dihydroxy-4-prenane-3 -one" / DNA Deoxyribonucleic acid / EGF Epidermal growth factor

The purpose of this study was to monitor cardiovascular and endocrine changes in sedentary and training females during a six week period, and to assess the accuracy of a new, low-invasive sampling methodology (electrosonophoresis). Changes in fitness were measured using oxygen consumption (VO2). The impact on VO2 of sleep quality, sleep duration and alcohol consumption (recorded in sleep logs) was assessed. Cortisol, testosterone and growth hormone levels in plasma were monitored for acute changes following fitness tests, and chronic changes related to training, oral contraceptive use or alcohol consumption. Hormone concentrations in blood and saliva samples were compared to those in interstitial fluid (obtained using electrosonophoresis) to investigate the accuracy of electrosonophoresis. Mean VO2 increased by 3.3 ± 1.3mL/kg/min between Week 1 and Week 5 and the changes detected in heart rate (HR) during the fitness tests suggest that aerobic fitness of the training participants increased across the study. No significant associations between sleep quality, sleep duration or alcohol consumption and VO2 were detected. No acute changes in plasma hormone concentrations following fitness tests were detected. No chronic changes in plasma cortisol or testosterone concentrations were detected, although a non-significant trend towards increased plasma GH levels in training participants was detected. Resting plasma cortisol levels were significantly lower in oral contraceptive users compared with non-users. Plasma testosterone and growth hormone levels were unaffected by oral contraceptive use. Alcohol consumption had no acute detectable effects on plasma concentrations of the three hormones. Plasma testosterone levels were higher in participants who abstained from alcohol, and higher plasma growth hormone levels were detected in heavy drinkers. These results contrast with published reports. Concentrations of the three hormones in interstitial fluid and plasma exhibited highly significant positive correlations (r2 > 0.98) with an interstitial fluid:plasma concentration ratio of about 1:10 in each case. Equations to predict plasma concentrations of cortisol, testosterone and growth hormone from interstitial fluid concentrations have been derived. The electrosonophoretic method apparently provides an accurate, painless, low-invasive method for prediction of the plasma levels of these three hormones. This technology has far-reaching implications for research in human, animal and biomedical fields.

Consumers' risk perceptions are examined to explain the underlying reasons for consumer concern associated with milk from dairy herds treated with recombinant bovine growth hormone (rbGH). A focus group study was employed as an initial step in exploring the primary influences of consumer apprehension toward rbGH's use. The information obtained through the focus group sessions was invaluable in strengthening empirical measures of the factors affecting risk perception, and in formulating concise survey questions for a national study. Data from a nationwide survey of 1,910 primary household food purchasers were used in understanding the influence of risk characteristics on consumers' risk perceptions toward rbGH treated herd milk, as well as investigating consumer risk perception profiles. One conclusion is evident from the data, consumers remain concerned about the rbGH product despite FDA approval for commercial use. Results suggest that particular characteristics of the rbGH product hypothesized as being more risky and less tolerable elicit consumer outrage perceptions. Results also showed systematic differences between consumers, producing a range of risk perception profiles. Overall, the results support the idea that consumers' risk perceptions are multi-dimensional and differ in emphasis compared to the risk assessments by scientific experts. Consumers' risk perceptions warrant recognition as playing a vital role in product acceptance. A recommendation proposed for those involved in risk assessment is to integrate consumer beliefs and perceptions into assessments of risk, perhaps increasing consumer trust and reducing product apprehension. Additionally, the range of risk perceptions among consumers imply that one public policy strategy is unlikely to satisfy all consumers. Risk communicators can design more effective risk communication strategies by understanding the ways consumers differ in their behavioral response to a particular perceived concern. / Graduation date: 1997

The present study used Escherichia coli¡]BL21¡^that contained pET-23a-bpGH plasmids, to express black porgy growth hormone ¡]bpGH¡^. The bpGH was refolded at pH 11.3 in the presence of catalytic amounts of cysteine and purified by ion exchanger chromatography and gel filtration chromatography. The purified bpGH is a monomer and has a molecular weight of 22 kDa. Using the bpGH, the effects of the growth hormone on growth, essential amino acid deposition and nonspecific immunity in black porgy were studied. The experiment was a 4*3 ¡]diet*GH¡^ factorial design. Four experimental diets were formulated in that fish meal was replaced by the mixture of soya protein and gelatin so that fish meal / soya mixture = 100 / 0, 75 / 25, 50 / 50 and 25 / 75, respectively. GH treatments included non-injection, once per 3 days and once per 12 days. GH was injected intramuscularly at a dosage of 0.05 &#x00B5;g / g wet body weight. The growth trial lasted for 72 days. The results showed that GH administration significantly enhanced weight gain, feed efficiency, protein efficiency ratio and muscle methionine concentration of the fish. GH injection improved the growth performance of the fish fed low protein quality diets to a level equals to the groups fed high protein quality diets. These results indicate that GH injections enhanced the perferential absorption and deposition of the first limiting amino acid methionine from the diets. In addition, GH administration enhanced alternative complement activity and increased serum lysozyme concentration, implicating the enhancement of the immunity.

published_or_final_version / Zoology / Master / Master of Philosophy