Sun, Minghui. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 125-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Um dos fatores que regula o córtex adrenal é o hormônio adrenocorticotrópico, ACTH, no entanto, o fator de crescimento de fibroblastos do tipo 2, FGF2, e os peptídeos N-terminais da pro-opiomelanocortina, N-POMC, também podem estar envolvidos. As vias de sinalização das proteínas quinases: ERK, JNK e p38, juntamente com outras vias como PKA, PKC e PI3K/Akt são importantes para a definição trófica das células. Nós analisamos a importância destas vias de sinalização e sua influência na viabilidade, proliferação e morte celular, induzidas pelo ACTH, FGF2 e N-POMC, utilizando inibidores farmacológicos e moleculares em culturas primárias de células adrenocorticais, células glomerulosa e fasciculadas/reticulares. Nossos resultados mostram que as vias mediadoras envolvidas na resposta proliferativa do FGF2 e da N-POMC são, respectivamente, as vias ERK/JNK e ERK/JNK/Akt. Por outro lado, a resposta pró-apoptótica promovida pelo ACTH é mediada pela via p38, provavelmente associada à ausência de ativação das vias relacionadas com a sobrevivência, como as vias ERK e JNK. / One of the factors that regulate adrenal cortex is the adrenocorticotrophic hormone, ACTH, however, the fibroblast growth factor type 2, FGF2) and pro-opiomelanocortin N-terminal peptides, N-POMC, might also be involved. The mitogen-activated protein kinase pathways: ERK, JNK and p38, together with other signaling pathways such as PKA, PKC and PI3K/Akt are important for cells trophic definition. We analyze the importance of these pathways and their influence in viability, proliferation and cell death stimulated by ACTH, FGF2 and N-POMC, using pharmacological and molecular inhibitors in primary culture of adrenocortical cells, glomerulosa and fasciculata/reticularis cells. Our results show that the mediating signaling pathways involved in FGF2 and N-POMC proliferative effects are, respectively, ERK/JNK and ERK/JNK/Akt. On the other hand, the pro-apoptotic response promoted by ACTH is through p38 signaling, probably associated with the absence of activation of other pathways involved with cell survival, like ERK and JNK.

Neonatal hypoxic-ischemic encephalopathy (HIE) is a common clinical problem. Tanshinone IIA is a compound purified from the Chinese herb Danshen ( Radix Salviae Miltiorrhiza Bge). Thrombopoietin (TPO) and Erythropoietin (Epo) are hematopoietic growth factors. The effects of tanshinone IIA, EPO and TPO on hypoxia-ischemia brain injury were investigated in this study, using in vitro model of neural cell culture and an in vivo model of hypoxic-ischemic brain damage. / Our observation provided the first evidence showing the expression of functional TPO receptor c-mpl in central nervous system. It revealed that novel agents TPO, EPO and tanshinone IIA have neuroprotection effects against brain injury induced by hypoxia-ischemia in neonatal rats, and these agents could be developed for clinical applications. / To investigate the effect of TPO, EPO and tanshinone IIA on in-vivo neural protection, a neonatal rat model of hypoxic-ischemic brain damage was established. Our results demonstrated significant and sustained brain injury in the hypoxic-ischemic and vehicle-treated group, measured by the reduction in relative weights of the ipsilateral (right) to the contralateral (left) brain at 1 and 3 weeks post-surgery, compared with those of sham-operated animals. At 3 weeks post-surgery, the hypoxic-ischemic animals had decreased cortical neuron density quantified by neuron-specific enolase (NSE) staining, and compromised sensorimotor functions in response to the postural reflex test. Treatment with TPO, EPO and tanshinone IIA significantly reduced the severity of brain injury, as indicated by the significantly increased ipsilateral brain weight and neuron density. Recoveries of sensorimotor functions (p < 0.05) and histopathology were also observed in animals that received TPO, EPO and tanshinone IIA. The plasma of tanshinone IIA-treated animals exhibited higher antioxidant activities (oxygen radical absorbance capacity assay) than those from vehicle-treated rats. / TPO and TPO receptor (c-mpl) mRNA was identified in human cerebral hemispheres, cerebellum, mouse neural progenitor cell line C17.2 and four neuroblastoma cell lines (SK-N-MC, MHH-NB-11, SK-N-AS and SH-SY-5Y) using RT-PCR methods. TPO proteins were detected in human cerebrospinal fluid (CSF) and plasma by ELISA. Furthermore, TPO receptor c-mpl was confirmed in human cerebral hemispheres, hippocampus, cerebellum, brainstem and spinal cord using immunohistostaining. TPO had a stimulating effect on the growth of neural progenitor cell C17.2 in culture via the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway as demonstrated by Western blot. The anti-apoptotic effects of TPO, EPO on C17.2 cells were demonstrated by staining with Annexin-V and PI. EPO exerted a protective effect against SHSY-5Y cell damage induced by NMDA (N-methyl-d-aspartate), as demonstrated by the MTT and LDH assay. The anti-oxidative property of tanshinone IIA was studied in the C17.2 cell line. Tanshinone IIA increased the viability of these cells subjected to 2,2'-azobis (2-amidino propane hydrochloride) (AAPH)-induced oxidative stress. / by Xia Wen-Jie. / "May 2005." / Advisers: Kwok-Pui Fung, Tai-Fai Fok. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0126. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 126-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 4 uppsatser.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 130-141.

Um dos fatores que regula o córtex adrenal é o hormônio adrenocorticotrópico, ACTH, no entanto, o fator de crescimento de fibroblastos do tipo 2, FGF2, e os peptídeos N-terminais da pro-opiomelanocortina, N-POMC, também podem estar envolvidos. As vias de sinalização das proteínas quinases: ERK, JNK e p38, juntamente com outras vias como PKA, PKC e PI3K/Akt são importantes para a definição trófica das células. Nós analisamos a importância destas vias de sinalização e sua influência na viabilidade, proliferação e morte celular, induzidas pelo ACTH, FGF2 e N-POMC, utilizando inibidores farmacológicos e moleculares em culturas primárias de células adrenocorticais, células glomerulosa e fasciculadas/reticulares. Nossos resultados mostram que as vias mediadoras envolvidas na resposta proliferativa do FGF2 e da N-POMC são, respectivamente, as vias ERK/JNK e ERK/JNK/Akt. Por outro lado, a resposta pró-apoptótica promovida pelo ACTH é mediada pela via p38, provavelmente associada à ausência de ativação das vias relacionadas com a sobrevivência, como as vias ERK e JNK. / One of the factors that regulate adrenal cortex is the adrenocorticotrophic hormone, ACTH, however, the fibroblast growth factor type 2, FGF2) and pro-opiomelanocortin N-terminal peptides, N-POMC, might also be involved. The mitogen-activated protein kinase pathways: ERK, JNK and p38, together with other signaling pathways such as PKA, PKC and PI3K/Akt are important for cells trophic definition. We analyze the importance of these pathways and their influence in viability, proliferation and cell death stimulated by ACTH, FGF2 and N-POMC, using pharmacological and molecular inhibitors in primary culture of adrenocortical cells, glomerulosa and fasciculata/reticularis cells. Our results show that the mediating signaling pathways involved in FGF2 and N-POMC proliferative effects are, respectively, ERK/JNK and ERK/JNK/Akt. On the other hand, the pro-apoptotic response promoted by ACTH is through p38 signaling, probably associated with the absence of activation of other pathways involved with cell survival, like ERK and JNK.

The human pancreatic cancer cell line T3M4, is known to produce transforming growth factor-alpha (TGF-alpha); as well as overexpress the receptor for this ligand, epidermal growth factor (EGF) receptor. TGF-alpha messenger RNA (mRNA) levels were assayed using northern blot, after addition of epidermal growth factor or TGF-alpha. The level of TGF-alpha mRNA was found to increase 2-fold at 2 hours and then return to near basal levels at 10 hours, after treatment with either ligand. Both ligands were also equipotent in a 2 hour dose response assay, with half maximal stimulation seen at 1 nM and maximal stimulation reached at 4 nM. Furthermore, there appeared to be a 2-fold increase in TGF-alpha transcription as determined by nuclear runoff experiments. Induction of TGF-alpha mRNA coupled with the overexpression of the EGF receptor, may result in a potent autocrine cycle; which may be found in other cancers.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The complexity of microbial systems has presented serious obstacles to the quantification of fermentation processes. Using computer modelling techniques progress has been made in monitoring, controlling and optimising microbial systems using material balancing techniques and empirical process models. The Monod equation is among the most commonly used models and is based on empirical findings with no mechanistic basis. Monod presents a simple model to describe the growth of a cell in a defined nutrient environment. The Monod equation is mathematically analogous to the formula that was proposed by Michaelis and Menten to describe enzyme kinetics. Both equations describe a hyperbolic function with a half-saturation constant (K_s in the monod equation and K_m in the Michaelis Menten equation) but the meaning of the two saturation constants K_s and K_m is different. In number of studies K_s and K_m are used as if they are equivalent. In contrast to Michaelis-Menten kinetics, which describes a process catalysed by a single enzyme, Monod kinetics describes an overall process involving thousands of enzymes. The Monod equation describes the specific growth rate of a microbial cell as the function of a limiting substrate concentration. The aim of this study was to test this principle, for Saccharomyces cerevisiae VIN13 under glucose limited aerobic chemostat conditions. The VIN13 was observed to follow the Monod description and when compared with other growth kinetic models gave one of the best fits to the data. A functional relationship between the half-saturation constant, K_s, and Michaelis Menten constant, K_m, was there after derived. This was achieved by using metabolic control analysis (MCA) to explain when K_m of the transporter becomes equal to the K_s. Using the deductions obtained from MCA a core kinetic model was then formulated to demonstrate that the K_s can either be smaller, equal or higher than the K_m of the transporter, depending on the flux control distribution in the model. / AFRIKAANSE OPSOMMING: Die kwantifisering van fermentasieprosesse word ernstig belemmer deur die kompleksiteit van mikrobiale sisteme. Deur gebruik te maak van rekenaar-ondersteunde modelleringstechnieke vir die opstelling van massa balans vergelykings en empiriese prosesmodelle is vordering gemaak in die waarneming, beheer en optimalisering van mikrobiale sisteme. Die Monod vergelyking is een van die mees gebruikte groeimodelle en is gebaseer op empiriese bevindings - die model het nie ‘n meganistiese grondslag nie. Die Monod vergelyking is wiskundig ekwivalent aan die vergelyking wat opgestel is deur Michaelis en Menten vir die beskrywing van ensiemkinetika. Beide vergelykings beskryf ‘n hyperboliese kurwe met ‘n konstante wat die halfversadigingswaarde aangee vir substraat (Ks in die Monod vergelyking en Km in die Michaelis-Menten vergelyking), maar die betekenis van die twee versadigingskonstantes is verskillend. In ‘n aantal studies word die Ks en Km waardes gebruik asof hulle gelyk is aan mekaar. In teenstelling met die Michaelis- Menten kinetika wat ‘n enkel ensiem-gekataliseerde reaksie beskryf, beskryf die Monod vergelyking ‘n proses wat duisende ensieme behels. Die Monod vergelyking beskryf die spesifieke groeitempo van ‘n bakteriële sel as ‘n funksie van die beperkende substraatkonsentrasie. Die doel van hierdie studie was om hierdie beginsel te toets vir Saccharomyces cerevisiae VIN13 wat onder glukose beperkte, aerobiese kondisies in ‘n chemostat gekweek word. Die VIN13 groei kon goed beskryf word met die Monod model, wat in vergelyking met ander groeimodelle een van die beste passings vir die meetpunte het gegee. Vervolgens is ‘n funksionele verwantskap afgelei tussen Ks en Km; deur gebruik te maak van metabole kontrole analise (MCA) kon verduidelik word wanneer die Ks gelyk is aan die Km van die transporter vir die beperkende substraat. Deur gebruik te maak van die MCA analise is ‘n eenvoudige kinetiese model opgestel om aan te toon dat die Ks kleiner, gelyk aan of groter kan wees as die Km van die transporter, afhanklik van die fluksie-kontrole verdeling in die model.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Obstetrics and Gynaecology / Master / Master of Philosophy