published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Medical Sciences

Thesis (M.S.)--University of Louisville, 1996. / School of Dentistry, Program in Oral Biology. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Louisville, 1996. / School of Dentistry, Program in Oral Biology. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Louisville, 1996. / School of Dentistry, Program in Oral Biology. Includes bibliographical references.

Wong King Yee. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 117-131). / Abstracts in English and Chinese. / Committee Memebers --- p.i / Acknowledgement --- p.ii / Abstract --- p.iii / 摘要 --- p.vi / List of Tables --- p.viii / List of Figures --- p.xiii / Abbreviations --- p.xv / Content --- p.xvii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Colonic fermentation --- p.1 / Chapter 1.1.1 --- The large intestine and the intestinal microflora --- p.1 / Chapter 1.1.2 --- Major substrates and products of colonic fermentation --- p.2 / Chapter 1.1.3 --- Beneficial bacteria --- p.6 / Chapter 1.2 --- Prebiotics --- p.7 / Chapter 1.2.1 --- Definitions of probiotics and prebiotics --- p.7 / Chapter 1.2.2 --- General characteristics of prebiotics --- p.8 / Chapter 1.2.3 --- Current studies on prebiotics --- p.9 / Chapter 1.2.3.1 --- Non-β3-glucan typed prebiotics --- p.9 / Chapter 1.2.3.2 --- β-glucan type prebiotics --- p.11 / Chapter 1.3 --- Potential β-glucan type prebiotics --- p.12 / Chapter 1.3.1 --- Commercial sources of β (l→3) glucans as potential prebiotics --- p.12 / Chapter 1.3.1.1 --- Pachyman (PAC) and carboxymethylated-pachyman (CM-PAC)… --- p.13 / Chapter 1.3.1.2 --- Curdlan (CUR) and carboxymethylated curdlan (CM-CUR) --- p.13 / Chapter 1.3.1.3 --- Laminarian (LAM) --- p.14 / Chapter 1.3.2 --- Non-digestible carbohydrates (NDC) from mushroom --- p.14 / Chapter 1.3.2.1 --- Mushroom sclerotia as a good source of β-glucan --- p.14 / Chapter 1.3.2.2 --- Poria cocos (PC) sclerotia --- p.15 / Chapter 1.3.2.3 --- Oligosaccharide preparation from PC sclerotium --- p.16 / Chapter 1.4 --- Microbial analysis by molecular methods --- p.19 / Chapter 1.4.1 --- Traditional cultural techniques --- p.19 / Chapter 1.4.2 --- Newly emerging molecular techniques --- p.23 / Chapter 1.5 --- Objectives and significance of the present study --- p.27 / Chapter Chapter 2 --- Materials and Methods --- p.28 / Chapter 2.1 --- Materials --- p.28 / Chapter 2.1.1 --- Commercial β-glucans --- p.28 / Chapter 2.1.2 --- β-glucan from Poria cocos sclerotium --- p.28 / Chapter 2.2 --- Chemical characterization of Poria cocos sclerotium --- p.30 / Chapter 2.2.1 --- Lowry method for soluble protein determination --- p.30 / Chapter 2.2.1.1 --- Reagents --- p.30 / Chapter 2.2.1.2 --- Determination of soluble protein content --- p.30 / Chapter 2.2.2 --- Total sugar content analysis (Phenol-sulphuric acid method) --- p.31 / Chapter 2.2.3 --- Total dietary fiber analysis --- p.31 / Chapter 2.2.3.1 --- Digestible carbohydrate and protein removal by enzyme treatment --- p.32 / Chapter 2.2.3.2 --- Total dietary fiber content determination --- p.32 / Chapter 2.3 --- Structural characterization of PSS and other commercial β-glucans --- p.35 / Chapter 2.3.1 --- Monosaccharide profile study by gas chromatography (GC) --- p.35 / Chapter 2.3.1.1 --- Acid depolymerisation --- p.35 / Chapter 2.3.1.2 --- Neutral and amino sugar derivatization --- p.35 / Chapter 2.3.1.3 --- Determination of neutral sugars by gas chromatography (GC) --- p.36 / Chapter 2.3.2 --- Structural study of polysaccharides by methylation --- p.37 / Chapter 2.3.2.1 --- Preparation of dry dimethyl sulfoxide (DMSO) --- p.37 / Chapter 2.3.2.2 --- Preparation of methylsulfinyl methyl sodium (CH3SOCH2-Na+) from the dry DMSO and sodium hydride --- p.37 / Chapter 2.3.2.3 --- Methylation procedure --- p.38 / Chapter 2.3.2.4 --- Preparation of partially methylated alditol acetates (PMAAs) --- p.39 / Chapter 2.3.2.5 --- Analysis of the PMAAs by GC-MS --- p.39 / Chapter 2.3.3 --- Intrinsic viscosity determination --- p.40 / Chapter 2.4 --- Enzymatic digestion of PSS --- p.43 / Chapter 2.4.1 --- Optimization of digestion Conditions --- p.43 / Chapter 2.4.2 --- Large scale oligosaccharide preparation by preparative HPLC --- p.43 / Chapter 2.5 --- In vitro fermentation of β-glucans --- p.45 / Chapter 2.5.1 --- Static Batch culture in vitro fermentation using human fecal inoculum --- p.45 / Chapter 2.5.2 --- Determination of organic matter disappearance (OMD) --- p.47 / Chapter 2.6 --- Gas chromatographic determination of SCFAs --- p.49 / Chapter 2.7 --- Microbial identification and enumeration --- p.52 / Chapter 2.7.1 --- Oligonucleotide probes for fluorescent in situ hybridization --- p.52 / Chapter 2.7.2 --- Fluorescent in situ hybridization (FISH) --- p.52 / Chapter 2.7.2.1 --- Cell Fixation --- p.53 / Chapter 2.7.2.2 --- In situ hybridization --- p.53 / Chapter 2.8 --- Statistical analysis --- p.54 / Chapter Chapter 3 --- Results and discussions --- p.55 / Chapter 3.1 --- Chemical characterization of Poria cocos sclerotium --- p.55 / Chapter 3.2 --- Structural characterization of PSS & other commercial β-glucans --- p.56 / Chapter 3.2.1 --- Monosaccharide profile --- p.56 / Chapter 3.2.2 --- Glycosidic linkages in polysaccharides --- p.58 / Chapter 3.2.3 --- Molecular weight comparison as determined by intrinsic viscosity --- p.59 / Chapter 3.3 --- Preparation of β (1→3) glucose-based oligosaccharides --- p.66 / Chapter 3.3.1 --- Enzymatic digestion of PSS --- p.66 / Chapter 3.3.2 --- Preparation of (3 (1 →3) glucose-based oligosaccharides by preparative HPLC --- p.66 / Chapter 3.4 --- Batch culture in vitro fermentation --- p.70 / Chapter 3.4.1 --- Organic matter disappearance (OMD) --- p.70 / Chapter 3.4.2 --- Time course study of SCFA production --- p.74 / Chapter 3.4.2.1 --- Total SCFA production --- p.74 / Chapter 3.4.2.2 --- "Individual SCFA (Acetate, Propionate and Butyrate)" --- p.76 / Chapter 3.4.3 --- Overall production of total and individual SCFA --- p.84 / Chapter 3.4.4 --- Molar ratio of SCFAs --- p.90 / Chapter 3.4.5 --- Summary --- p.94 / Chapter 3.5 --- Microbial identification and enumeration by FISH --- p.95 / Chapter 3.5.1 --- Time course relationship --- p.95 / Chapter 3.5.1.1 --- Total bacterial count --- p.95 / Chapter 3.5.1.2 --- Bifidobacteria --- p.97 / Chapter 3.5.2 --- Comparison of bifidogenic properties in the β-glucans --- p.105 / Chapter 3.5.3 --- Summary --- p.108 / Chapter 3.6 --- Correlation between various parameters during in vitro fermentation of β_ glucans --- p.110 / Chapter Chapter 4 --- Conclusions --- p.113 / Chapter 4.1 --- Prebiotic potential of β (1→3) glucans --- p.113 / Chapter 4.2 --- Future Work --- p.115 / List of References: --- p.117

beta-Glucans are a kind of non-digestible carbohydrate (NDC) that are known for their benefits for human gut health, but there are very few studies on their fermentability by human colon microbiota. In this study four beta-glucans were selected for in vitro fermentation by three bifidobacteria. The beta-glucans included those from a seaweed called Laminaria digitata (laminarin), barley, a bacterium called Alcaligenes faecalis (curdlan), and a mushroom sclerotia from Pleurotus tuber-regium. Inulin from Dahlia tubers was used as control. / The content of beta-glucan in the NDCs prepared from the mushroom sclerotium of Pleurotus tuber-regium was 80.8 % with proteins less than 1.0 %, while that of curdlan, barley and laminarin all have more than 95% beta-glucan. All the beta -glucans contained almost purely glucose as their sugar components with only trace amount of mannose ( < 2%) being found in laminarin. beta-glucan from barley had a MW of 590 kDa and a linear chain with mixed 1→3 and 1→4 beta-linkages in the ratio of 1:3. Curdlan had a beta-(1→3) linked unbranched linear chain with a MW of 10 to 30 kDa. Laminarin had a beta-(1→3) linked backbone with beta-(1→6) branches, having a MW of 6 kDa. beta-Glucan from mushroom sclerotia had a highly branched main chain with mixed glycosidic 1→3, 1→4 and 1→6 beta-linkages with a MW of 96 kDa. / Batch systems of in vitro fermentation of individual NDCs by B.longum subsp. infantis ( B. infantis), B. longum and B. adolescentis were carried out for 24 h under anaerobic condition. All the systems showed a significant drop (p< 0.05) of at least 0.5 units in their pH values. The populations of B. infantis increased by 3 log10 CFU on all the NDCs while those of B. longum and B. adolescentis increased by about 1 to 1.5 log10 CFU and 2 to 2.3 log10 CFU, respectively. Utilization of the NDCs by the bifidobacteria evaluated by organic matter disappearance ranged from 4.52% in barley to 41.3% in inulin. The total short chain fatty acid (SCFA) produced by B. infantis was higher than that in B. longum and B. adolescentis for all the beta -glucans. The SCFA profile of inulin and all beta-glucans produced by all the bifidobacteria was dominated by acetate (96%). The ratio of acetic : propionic : butyric acid in the SCFA profile of the fermentation of all the beta-glucans by B. infantis was 8: 1: 1, which was very different from that of B. longum and B. adolescentis. / Based on the in vitro fermentation results, B. infantis was selected for a mechanistic study on the fermentation of the Pbeta-glucans from different sources by proteomic and molecular biology approaches. In the proteomic study, the gels of the two-dimensional difference gel electrophoresis (2D-DIGE) containing the total proteins from the B. infantis cells fermented with beta-glucans from barley, seaweed and mushroom sclerotia were compared with each other to isolate the differentially expressed protein spots. In all the comparisons, a total number of 198 protein spots were identified based on their mass spectra. These proteins were classified according to their functional annotation, including ABC transporters, phosphotransferase system (PTS), transketolase and others. Several genes encoding the proteins that probably play a role in the transport and degradation of beta-glucans including the ABC transporter gene, PTS gene and membrane protein gene underwent real time RT-PCR for transcriptional analysis. Hydrolytic enzyme activity assay showed that intracellular beta-1, 3 glucanase activity was present when B. infantis was incubated with beta-glucans from seaweed and mushroom. / Based on the above results, a model for beta-glucan catabolism in B. infantis was proposed. The fbeta -glucan molecules might be captured and imported inside the bacterial cells either by ABC transporters or PTS. They were then subjected to hydrolysis by glucan beta-1, 3 glucosidase. The released glucose molecules were readily incorporated into the central fermentation pathway, the 'bifid shunt', in which the hydrolyzed residues were further degraded or exported. This study has deepened our understanding on the fermentation of beta-glucans by bifidobacteria and demonstrated the potential of beta-glucans to be used as a novel prebiotic. / Zhao, Jinyang. / Source: Dissertation Abstracts International, Volume: 73-08, Section: B, page: . / Adviser: Peter Chi-Keung Cheung. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 147-162). / 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 Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

No description available.

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Jan. 7, 2010). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Science and Technology, Department of Agricultural, Food and Nutritional Science, University of Alberta." In the title, [beta] is represented by the Greek letter. Includes bibliographical references.

The Saccharomyces cerevisiae genes KRE6 and SKN1 encode a novel pair of highly homologous proteins involved in cell wall (1$ rightarrow$6)-$ beta$-glucan assembly. Disruption of KRE6 results in a slow growing, killer-toxin resistant mutant possessing reduced levels of structurally wild type (1$ rightarrow$6)-$ beta$-glucan. Although deletion of SKN1 has no effect on killer sensitivity, growth, or (1$ rightarrow$6)-$ beta$-glucan levels, SKN1 appears to overlap in function with KRE6, suppressing kre6 null alleles in a dosage-dependent manner. Strains deleted of both KRE6 and SKN1 possess an exaggerated growth phenotype, enhanced cell wall ultrastructure defects, and more severe (1$ rightarrow$6)-$ beta$-glucan reductions compared with either single disruptant. Moreover, the residual (1$ rightarrow$6)-$ beta$-glucan polymer in kre6 skn1 double mutants is smaller in size and altered in structure. Since single disruptions of either gene lead to structurally wild type (1$ rightarrow$6)-$ beta$-glucan, KRE6 and SKN1 appear to function independently and to act early in the assembly of the polymer, possibly as glucan synthases. Consistent with their direct role in the assembly of this polymer, both Kre6p and Skn1p possess C-terminal domains with significant sequence similarity to two recently identified glucan-binding proteins. / An initial characterization of Kre6p and Skn1p reveal both to be phosphorylated integral-membrane glycoproteins, with Kre6p likely localized to the Golgi apparatus. The topology implied by the post-translational modifications of Kre6p and Skn1p, offers the potential for both proteins to link cytoplasmic regulation with a secretory pathway-based assembly of the (1$ rightarrow$6)-$ beta$-glucan polymer. The observed phosphorylation of both Kre6p and Skn1p prompted an examination for genetic interactions with suspected cell wall regulating kinases. KRE6-dependent suppression of the pkc1 lysis defect, as well as synthetic lethal interactions between several KRE genes and members of the PKC1-mediated MAP kinase pathway, supports a role for the PKC1 pathway in regulating synthesis of cell wall components, including (1$ rightarrow$6)-$ beta$-glucan.

Analyses of genes involved in yeast cell wall $ beta$1,6-glucan assembly have identified CWH41, PTC1/CWH47, EXG1, PBS2 and a family of genes related to the human oxysterol binding protein, OSBP. CWH41 encodes a novel membrane N-glycoprotein located in the ER. Disruption of CWH41 leads to a K1 killer toxin resistant phenotype, and a 50% reduction in the $ beta$1,6-glucan level The $cwh{ it 41 /} Delta$ mutant displayed strong synergistic defects with $kre{ it 1 /} Delta$ or $kre{ it 1 /} Delta$ null mutations: the $cwh{ it 41 /} Delta kre{ it 6 /} Delta$ double mutant showed a slow-growth phenotype and a 75% reduction in $ beta$1,6-glucan level, and cells containing $cwh{ it 41 /} Delta kre{ it 6 /} Delta$ double mutations were nonviable. These results indicate that CWH41 is involved in the assembly of $ beta$1,6-glucan. / PTC1/CWH47 encodes a serine/threonine phosphatase, PBS2 is the structural gene for a MAPK kinase, and EXG1 codes for an exo-$ beta$-glucanase. Overexpression of EXG1 led to a killer resistant phenotype and a reduction in ($ beta$1,6-glucan level; whereas the $exg{ it 1 /} Delta$ mutant displayed modest increases in killer sensitivity and $ beta$1,6-glucan levels. Disruption of PTC1/CWH47 and overexpression of PBS2 resulted in similar $ beta$-glucan related phenotypes, with elevated EXG1 transcription, increased Exg1p activity, reduced $ beta$1,6-glucan levels, and resistance to killer toxin. The killer resistant phenotype caused by PTC1/CWH47 disruption or PBS2 overproduction were partially suppressed by the $exg{ it 1 /} Delta$ null mutation. These results suggest that Ptc1p/Cwh47p and Pbs2p play opposing regulatory roles in $ beta$-glucan assembly, and this is effected in part by modulating Exg1p activity. / Three yeast genes, KES1, HES1 and OSH1, whose products show homology to the human oxysterol binding protein, were also identified. Mutations in these genes resulted in sterol-related phenotypes, which include tryptophan-transport defects and nystatin resistance. In addition, mutant combinations showed small but cumulative reductions in membrane ergosterol levels. The three genes are also functionally related; since overexpression of HES1 or KES1 alleviated the tryptophan-transport defect in $kes{ it 1 /} Delta$ or $osh{ it 1 /} Delta$ mutants, respectively. These observations implicate the KES1-related gene family in ergosterol synthesis and provide comparative evidence of a role for human OSBP in cholesterol synthesis.