O transporte de α-metil glicosídio ( α-MG) em Saccharomyces cerevisiae foi recentemente reportado como transporte ativo, do tipo simporte de &$945;-MG com H+ mediado pela permease Agt1p. A cepa AP77-11B (cepa selecionada em nosso laboratório) 14C-α-MG pelo mecanismo descrito como difusão facilitada porque não existe co-transporte de H+ durante o transporte de α-MG. Os genes HXT1-HXT17 pertencem à família dos transportadores de hexoses em Saccharomyces cerevisiae. Então, nós decidimos investigar a possibilidade que o transporte de α-MG poderia ser mediado pelos transportadores de hexoses. Nós demonstramos que cepa MC966A (tipo selvagem), KY73 (isogênica com MC966A mas deletada nos HXT1-7), BSY08 (isogênica com KY73 com o AGT1 deletado), BSY09 (isogênica com MC966A com o AGT1 deletado) e a EBY.VW4000 (hxt1-17 agt1 gal2-null), não cresceram em α-MG como fonte de carbono. Além disso, estas cepas não transportaram α-MG por difusão facilitada quando as células foram cultivadas em meio com maltose, levando-nos a concluir que os transportadores de hexoses não estavam envolvidos no transporte de α-MG. Nós observamos que a cepa AP77-11B apresentou alta atividade de α-metilglicosidase periplásmica quando as células foram cultivadas em α-MG. Esta atividade enzimática foi ensaiada usando um método descrito primeiramente para invertase periplásmica, no qual as células eram incubadas com fluoreto de sódio, um inibidor da enolase, antes da incubação com α-MG. Então, a glicose produzida durante a hidrólise do -MG poderia ser determinada. A atividade extracelular só está presente em células cultivadas em -αMG. Células de-reprimidas não mostraram atividade de alpha-metilglicosidase. Os parâmetros cinéticos determinados para α-metilglicosidase, indicaram que esta enzima tem baixa afinidade para o alpha-MG. Além do mais, a atividade específica da alpha-metilglicosidase periplásmica aumentou ao longo da curva de crescimento em α-MG. Os resultados reportados mostraram que existem duas vias de utilização de α-MG em Saccharomyces cerevisiae. Uma via é mediada pela Agt1p, responsável pelo transporte ativo de α-MG. Na outra via, a α -metilglicosidase é secretada para o espaço periplásmico das células. Então, a glicose produzida pela hidrólise do α-MG é transportada pelos transportadores de hexoses por difusão facilitada. / Alpha-Methyl glucoside ( alpha-MG) transport in Saccharomyces cerevisiae was previously reported to be an active transport, a H+ -symport mediated by the Agt1p permease. Strain AP77-11B (a strain obtained in our laboratory) takes up 14C- alpha-MG by a mechanism which was ascribed to be facilitated diffusion since there is no H+-cotransport during the alpha-MG uptake. The HXT1-HXT17 there is no H genes belong to a family of hexose transporters in Saccharomyces cerevisiae. Therefore, we decided to investigate the possibility that -MG transport could be mediated by hexose transporters. We demonstrated that strains MC966A (w.t.), KY73 (isogenic to MC966A but hxt1-hxt7-null), BSY08 (isogenic to KY73 with AGT1 deleted), BSY09 (isogenic to MC966A with AGT1 deleted) and even strain EBY.VW4000 (hxt1-hxt17 agt1 gal2-null), were not able to grow on alpha-MG as the sole carbon source. Moreover, none of them presented alpha-MG transport by facilitated diffusion when the strains were grown on maltose leading us to conclude that the HXT glucose transporters were not involved in alpha-MG transport. We found that strain AP77-11B displayed a high periplasmic alpha-methylglucosidase activity when cells were grown on alpha-MG. This enzymatic activity was assayed using a method first described for periplasmic invertase in which cells were incubated with sodium fluoride, an inhibitor of enolase, prior to the incubation with alpha-MG. Then the glucose produced during alpha-MG hydrolysis could be accurately measured. The extracellular activity was present only in cells grown on alpha-MG. Glucose derepressed cells did not show periplasmic alpha-methylglucosidase activity.

Thesis advisor: Peter Ireland / We study historical hedge fund performance characteristics with a particular focus on the 2007 – 2009 Financial Crisis (the “Crisis”). Using the Credit Suisse Hedge Fund Indexes as proxies for broader hedge fund industry performance, we apply a factor model based on common investment strategies to determine if the broad industry or any particular hedge fund strategies have been able to deliver excess returns, or alpha. We find evidence that the broad hedge fund index did deliver statistically significant excess monthly returns of 0.39% (4.67% annualized) over the period January 1995 – January 2016, with seven of ten individual strategy indexes contributing. However, our results indicate that these excess returns were delivered primarily during the pre-Crisis period of January 1995 – November 2007. Over this period, the broad index delivered statistically significant monthly excess returns of 0.49% (5.93% annualized), with six of ten individual strategy indexes contributing. Our results do not indicate, however, that hedge funds delivered statistically significant monthly excess returns over the period December 2007 – June 2009 or over the period December 2007 – December 2012, which takes into account the uniquely drawn out recovery from the Crisis. We find that the broad index delivered statistically significant excess monthly returns of 0.23% (2.74% annualized) during the post-Crisis period, though these returns are less than half of the pre-Crisis period returns and only three individual strategy indexes contributed. We posit that this apparent shift in performance characteristics might be the result of a shift in the risk tolerances of hedge fund investors and managers following the Crisis. We conclude that, while hedge funds might certainly serve legitimate purposes in financial markets, they are not immune to financial crises, especially those as severe as the Crisis. / Thesis (BA) — Boston College, 2016. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Arts and Sciences Honors Program. / Discipline: Economics.

Fragestellung: Wir gingen der Frage nach, inwieweit genetische Variationen im Gen für den Tumor Nekrose Faktor-alpha einen Einfluß auf die Krankheitsprogression oder die Entstehung bzw. Ausprägung HIV-assoziierter Erkrankungen haben. Methoden: Die Promotorregion sowie die kodierenden Sequenzen des TNF-alpha-Gens wurden mittels SSCP-Analyse auf genetische Variationen untersucht. Anschließend erfolgte die Charakterisierung der häufigsten bekannten Promotorpolymorphismen mittels Restriktionsfragment-Längenpolymorphismus-Analyse (RFLP). Die Bestätigung der Polymorphismen der RFLP-Analyse erfolgte an ausgewählten Proben durch DNA-Fluoreszenzsequenzierung. In sämtlichen Fällen handelte es sich um singuläre Basentransitionen von Guanin zu Adenin. Ergebnisse: Unter Einbeziehung verschiedener Progressionsparameter wie der CD4-Zellzahl, des Zeitraumes vom ARC-Stadium zum AIDS-Stadium und AIDS-assoziierter Krankheiten wie dem Wasting Syndrom und der HIV-Enzephalopathie, erfolgte anschließend die statistische Analyse in Korrelation mit den ermittelten Genotypen. Es zeigte sich bei keiner der statistischen Analysen eine signifikante Assoziation mit einem bestimmten TNF-alpha-Genotyp. Schlußfolgerung: Es ist kritisch anzumerken, daß für einige Subanalysen die Größe der untersuchten Patientengruppe zu gering war, um eine statistische Aussagekraft für seltene Allele zu erreichen. Anhand der hier vorgelegten Ergebnisse hat der TNF-alpha-Genotyp weder einen Einfluß auf die Progression der HIV-Erkrankung noch auf die Ausbildung HIV-assoziierter Erkrankungen wie dem Wasting Syndrom oder der HIV-Enzephalopathie. / Objective: We determined whether variation of the tumor necrosis factor-alpha gene had an impact on HIV disease progression or the prevalence of hiv-associated diseases. Methods: The promotor region of the TNF-alpha gene were examined with SSCP analysis for polymorphisms in the promotor region. The most common promotor polymorphisms were characterized with restriction fragment length polymorphism analysis (RFLP). To confirm RFLP results DNA fluorescence sequenzing analyses were performed with selected samples. In all cases with diagnosis of promotor polymorphisms single base transitions from guanine to adenine were confirmed. Results: Statistical analyses correlated the genotypes with different markers for disease progression e.g. CD4-count, the period from ARC to AIDS and the occurance of HIV associated diseases (wasting syndrome, hiv encephalopathy). In none of the statistical analyses significant association with a certain TNF-alpha genotyp could be demonstrated. Conclusion: For some subanalysis the sample sizes were too small in order to be able to make safe statistical statements concerning rare allels. Regarding our results, none of the examined tumor necrosis factor-alpha promotor polymorphisms had an impact on HIV disease progression or the prevalence of hiv-associated diseases.

by Chun-kwok Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 181-196. / ABSTRACT --- p.i / ACKNOWLEDGEMENTS --- p.iii / ABBREVIATIONS --- p.iv / CHAPTER / Chapter 1. --- INTRODUCTION : An overview of Tumor Necrosis Factor ( TNF) / Chapter 1. --- The discovery of tumor necrosis factor (TNF) --- p.1 / Chapter 2. --- Production of tumor necrosis factor --- p.3 / Chapter 3. --- Physiochemical properties of TNF --- p.5 / Chapter 4. --- Biological activities of TNF on various cells in the mammal --- p.8 / Chapter 5. --- Mechanisms of anti-tumor action of TNF --- p.12 / Chapter 6. --- Clinical studies of Hr-TNF --- p.19 / Chapter 2. --- AIM OF INVESTIGATION --- p.23 / Chapter 3. --- MATERIALS AND METHODS / Chapter A. --- MATERIALS --- p.26 / Chapter B. --- METHODS / Chapter 1. --- Preparation of Reagents --- p.30 / Chapter 2. --- Cell Culture --- p.31 / Chapter 3. --- Lymphocytes proliferation --- p.32 / Chapter 4. --- In vitro production of tumor necrosis factor (TNF) by peritoneal macrophages of ICR mice --- p.33 / Chapter 5. --- Production of TNF in animals --- p.34 / Chapter 6. --- Determination of TNF titre --- p.35 / Chapter 7. --- Determination of TNF containing serum titre on EAT in vitro --- p.35 / Chapter 8. --- Mortality determination of mice --- p.36 / Chapter 9. --- "3H-Thymidine, 3H-uridine, 14C-leucine incorporation" --- p.36 / Chapter 10. --- Glucose uptake determination --- p.37 / Chapter 11. --- Whole body hyperthermic treatment of EAT bearing mice --- p.37 / Chapter 12. --- Lipolysis assay --- p.38 / Chapter 13. --- Statistical analysis --- p.39 / Chapter 4. --- IN VIVO PRODUCTION OF TUMOR NECROSIS FACTOR USING ZYMOSAN AND LIPOPOLYSACCHARIDE / INTRODUCTION --- p.40 / EXPERIMENTAL --- p.43 / RESULTS --- p.45 / DISCUSSION --- p.65 / Chapter 5. --- SIDE EFFECTS DURING IN VIVO PRODUCTION OF TUMOR NECROSIS FACTOR IN EHRLICH ASCITES TUMOR BEARING MICE / INTRODUCTION --- p.70 / EXPERIMENTAL --- p.72 / RESULTS --- p.74 / DISCUSSION --- p.93 / Chapter 6. --- MODIFIED PROCEDURE FOR THE IN VIVO PRODUCTION OF TUMOR NECROSIS FACTOR FOR THE TREATMENT OF EHRLICH ASCITES TUMOR BEARING MICE / INTRODUCTION --- p.98 / EXPERIMENTAL --- p.99 / RESULTS --- p.100 / DISCUSSION --- p.108 / Chapter 7. --- "COMBINED TREATMENTS OF IN VIVO PRODUCTION OF TUMOR NECROSIS FACTOR (TNF) WITH HYPERTHERMIA, METHOTREXATE (MTX), POLYRIBOINOSINIC-POLYRIBOCYTIDYLIC ACID (POLY I.C), N-(PHOSPHONACETYL)-L-ASPARTATE (PALA) ON EAT BEARING MICE" / INTRODUCTION --- p.111 / EXPERIMENTAL --- p.116 / RESULTS --- p.118 / DISCUSSION --- p.133 / Chapter 8. --- EFFECTS OF IN VIVO PRODUCTION OF TUMOR NECROSIS FACTOR ON EHRLICH ASCITES TUMOR CELLS CYTOTOXICITY / INTRODUCTION --- p.138 / EXPERIMENTAL --- p.140 / RESULTS --- p.142 / DISCUSSION --- p.151 / Chapter 9. --- SIDE EFFECTS OF TUMOR NECROSIS FACTOR AND LIPOPOLYSACCHARIDE ON RAT IN VITRO AND IN VIVO / INTRODUCTION --- p.154 / EXPERIMENTAL --- p.157 / RESULTS --- p.159 / DISCUSSION --- p.170 / Chapter 10. --- CONCLUSION AND OUTLOOK --- p.174 / BIBLIOGRAPHY --- p.181

by Chung-Pui Cheng. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 142-163.

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases. It is characterized by the presence of intracellular inclusions termed Lewy bodies (LBs) and Lewy neuritis (LNs) in the brain, in which α-Syn aggregates constitute the main component. Therefore, α-Syn aggregation was implicated in the pathogenesis of PD. Structurally α-Syn is a disordered protein with little ordered structure under physiological conditions. However, research of α-Syn has provided substantial information about its structural properties. The precise function of α-Syn is still under investigation. Research has also shown that metals, such as copper and iron, accelerate α-Syn aggregation and fibrillation in vitro and are proposed to play an important role in vitro. In this study, isothermal titration calorimetry was used to determine iron binding properties to α-Syn revealing the presence of two binding sites for iron with an affinity of 1.06 x 105 M-1 and a dissociation constant of ~ 10μM which is physiologically relevant to iron content in the brain. In addition, α-Syn was found to reduce iron in the presence of copper. This property was demonstrated via ferrozine based assay. In vitro, thoflavin-T fluorescence assay was used to investigate the mechanism by which metals induce α-Syn aggregation and whether it is related to metal binding. Metals, mainly copper and iron, caused 2-fold increase in the aggregation rate of WT α-Syn and its metal binding mutants. Linking that to the increased metal content in the brain, α-Syn aggregation can cause changes in tissue composition, thus altering the normal functional environment in the brain. Moreover, western blotting analysis showed that copper increases the aggregate formation in mammalian dopaminergic cells over-expressing α-Syn.

Parkinson’s disease (PD) is the second most common age-related neurodegenerative condition. It is neuropathologically characterised by the presence of Lewy pathology and the degeneration of the midbrain dopaminergic neurons from the substantia nigra pars compacta. Lewy pathology mainly consists of filamentous aggregated alpha-synuclein and familial forms of PD can be caused by genetic alternations in the SNCA gene encoding alpha-synuclein. Alpha-synuclein is primarily localised to neuronal presynaptic terminals and has been implicated in the maintenance of synaptic function. Studies have proposed that it regulates the docking, fusion, clustering and trafficking of neurotransmitter-loaded presynaptic vesicles. Nowadays, it is possible to model PD in vitro by obtaining adult somatic cells from patients, reprogramming them into induced pluripotent stem cells (iPSCs), and differentiating iPSCs into neurons. For this project, iPSCs derived from two PD patients, one harbouring the A53T SNCA mutation, the other a SNCA triplication, and three healthy individuals, were employed. In the initial stage, I optimised a neuronal differentiation protocol originally developed for human embryonic stem cells to produce neurons belonging to two distinct brain regions affected in PD, the forebrain and midbrain, from the available human iPSC lines. Next, I assessed the maturation of the generated neurons over time using protein expression and electrophysiological techniques. Finally, I examined PD-related phenotypes such as alpha-synuclein aggregation and release, susceptibility to cell death, and the redistribution of presynaptic proteins. All the iPSC lines used gave rise to forebrain and midbrain neuronal cultures. Maturation was similar across lines, as no consistent differences were observed in the changes of the expression of 4 repeat tau isoforms, presynaptic protein levels or electrophysiological properties over time. However, the emergence of astrocytes varied between cultures derived from distinct iPSC lines. No robust differences in alpha-synuclein release and susceptibility to cell death were detected between patient- and control-derived neurons. Apart from the presence of larger alpha-synuclein-positive puncta in patient-derived neurons, no other signs of alpha-synuclein aggregation were detected. Despite this, midbrain patient-derived neurons with a SNCA triplication exhibited a significant redistribution of presynaptic protein VAMP-2/synaptobrevin-2, which interacts with alpha-synuclein, relative to controls.

No description available.

Ko Samuel. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 230-252). / 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.

Neurodegeneration, the progressive and irrevocable loss of neuronal structure, is quickly becoming an imposing health concern in a globally ageing society. While specific neurodegenerative conditions exhibit specific clinical symptoms and progressions, a common neuropathological feature is the misfolding, oligomerisation and fibrillation of certain proteins causing neuronal stress and death. Parkinson’s disease, PD, has long been characterised by the death of nerve cells focused in the substantia nigra pars compacta region of the midbrain and deposition of large protein aggregates, called Lewy Bodies, throughout the central nervous system. More recently, the protein which forms these inclusion bodies was identified as alpha synuclein, αSyn, a ubiquitous neuroprotein with no known function. Furthermore, persons with mutations in the SNCA gene, which codes for αSyn, exhibit PD progression at a far younger age with a more severe phenotype, positively linking αSyn with PD. αSyn is an intrinsically disordered protein, IDP, and generally persists as such in solution and inside bacterial and mammalian cells. However, when in contact with a lipid bilayer the protein will embed upon the surface in an amphipathic alpha helical conformation and can also aggregate, forming toxic oligomeric and fibrillar species containing significant β-sheet identity. Its function as a helical apolipoprotein and subcellular localisation to both the nucleus and synapse has led researchers to suggest that αSyn has a role synaptic transmission and release. However, knocking out the protein does not reduce viability or produce pathological abnormalities in neuronal structure. The helical form of the protein may also persist as transient, metastable helical bundles which are non-toxic and resist aggregation. While a number of studies and tools have been reported and developed to investigate the toxic oligomeric/fibrillar forms of αSyn, very little attention has been accorded to the helical conformation. This thesis will redress this balance by producing tools which will allow us to mimic the helical form of αSyn, promote the active refolding of the full-length protein using a stable, helical peptide template and produce antibodies which recognise helical αSyn specifically for use in discovery and chaperone-like refolding. In Chapter 2 a region of αSyn (14 amino acids) was identified with a unique primary sequence located within a mutation prone section of the protein. Peptide ‘stapling’ technologies were then employed using a panel of monosubstituted ‘staple’ diastereomers, to produce a highly helical portion of αSyn. Using several other protein targets particular diastereomeric ‘staple’ combinations were analysed for obvious trends in helical content. Using solution NMR, backbone refined three dimensional structures of these helical peptides were produced which showed that they were faithful structural homologues of their parent helical proteins. In Chapter 3 the drug-like properties and therapeutic potential of stable, helical αSyn peptides were investigated. Using fluorescently labelled peptide substrates, ‘stapled’ peptides were shown to be far more cell penetrant than their wild type equivalents and demonstrated that the mechanism for cellular uptake appears to be specific. Furthermore, under harsh proteolytic conditions the ‘stapled’, helical peptides were far more resistant to hydrolysis than wild type or ‘stapled’, poorly helical peptides. The ‘stapled’ peptides were also highly soluble and did not appear to aggregate in a time-dependent manner. Using ion mobility mass spectrometry, it was shown that incubation of full-length protein with the ‘stapled’, helical peptides caused a contraction in the hydrodynamic radius of the protein. However, using solution NMR no active refolding of αSyn was observed when under the same conditions. Rather small perturbations in chemical shift were apparent which did not suggest that the αSyn protein folded into a discrete structural conformation, such as an alpha helix. In Chapter 4 the stable, helical αSyn peptide was employed as a conformational model and unique antigen in antibody discovery. Immunisation with the ‘stapled’, helical αSyn peptide initially produced a pool of polyclonal antibodies with a half log specificity for the helical peptide. After bespoke affinity chromatography this was increased to three log orders of specificity. Initial immunocytochemistry did not detect any helical αSyn protein in SH-SY5Y cells. To validate the helical epitope on the full-length protein in vitro an assay based around flow cytometry of synthetic vesicle structures was developed, with their synthesis, characterisation and binding of the αSyn protein described.