http://hdl.handle.net/1813/47 Search the Channel search http://dspace.library.cornell.edu/simple-search http://hdl.handle.net/1813/11452 Title: INFLUENCE OF RED WINE GRAPE PHENOLIC EXTRACTS ON GLUCOSYLTRANSFERASE ACTIVITY, ACIDOGENICITY, AND BIOFILM FORMATION OF STREPTOCOCCUS MUTANS. <br/> <br/>Authors: Thimothe, Joanne <br/> <br/>Abstract: Wine grapes are rich sources of potentially bioactive polyphenols. However, phenolic content is variable depending on grape variety, and may be modified during vinification. In this study, we investigated the influence of phenolic extracts from Vitis vinifera (Cabernet Franc and Pinot noir), V. Labrusca (Concord), and Vitis hybrids (Baco noir and Noiret) grapes on several virulence properties of Streptococcus mutans a well-known cariogenic bacterium. Grape phenolic extracts were prepared from whole fruit (WF) and fermented pomace (FP). The anthocyanin and flavan-3-ol content were variable depending on variety and type of extract (WF vs. FP). Nevertheless, all extracts inhibited the activity of GTF B between 60-80% at concentrations as low as 31.2 ug/ml; GTF B synthesizes insoluble glucans, which are critical for the formation, bulk and structural integrity of biofilms. Furthermore, the glycolytic pH-drop by S. mutans cells was inhibited by the extracts without affecting bacterial viability, an effect that can be attributed to partial inhibition of F-ATPase by the extracts (30-65% inhibition at 125 ug/ml). In general, phenolic extracts from V. vinifera were more effective than those from Vitis hybrids. The biological activity of FP was either as effective as or significantly better than WF extracts. The most effective extracts were examined for their ability to disrupt biofilm development by S. mutans using a saliva-coated hydroxyapatite biofilm model. Biofilms were treated for 1 minute twice daily with phenolic extracts from FP of Cabernet Franc and Baco noir. Biofilms treated with the extracts (at 1 mg/ml) resulted in significantly lower amounts of extracellular insoluble polysaccharides than those treated with vehicle control (P<0.01), which agrees well with the GTF B inhibition data. The reduction of insoluble polysaccharides production is highly relevant because they are the main components of the extracellular matrix of biofilms, and are associated with the pathogenesis of dental caries. Overall, the phenolic extracts, especially from pomace, are effective against specific virulence attributes of S. mutans and can disrupt the synthesis of extracellular polysaccharide matrix of biofilms. Fermented pomace could be a potential source for extraction of bioactive compounds for prevention or reduction of oral diseases, such as dental caries. Mon, 06 Oct 2008 14:23:22 GMT http://hdl.handle.net/1813/11432 Title: A Chemical Odyssey on the Martian Surface <br/> <br/>Authors: Walimuni Devage, Suniti <br/> <br/>Abstract: The Mars Odyssey Gamma Subsystem (GS) underpins most of this narrative, sensing the planetary subsurface gamma photons. Midlatitudinal maps of Ca, Cl, Fe, K, H2O, Si, and Th mass fractions have been generated with the GS. We first determine whether GS estimates represent chemical composition on the ground by computing representative in situ compositions for Pathfinder, Spirit, Opportunity, and Viking 1 landing sites. GS estimates compare favorably with the in situ estimates for Cl and K. However, the GS-determined Fe content at each landing site is consistently higher than the in situ value. Nevertheless, these comparisons reassure us that the GS data are indeed representative of the actual surface of Mars. Next, we describe statistical analysis methods with particular emphasis on comparing distributions, computing multivariate correlations, and modeling optimal predictor sets hierarchically. Examples of their application using the GS data set clarify their use in the geochemically oriented chapters that follow. Multivariate analyses indicate a remarkable correlation among K, Th, and the areal fraction of the mineralogically distinct surface type 2 (ST2). With our chemical insight into ST2, we consider the likelihood of different genetic scenarios that have been proposed previously. Consistent with the multivariate results, we observe significant enrichment of both K and Th in regions representative of ST2. In addition, Si does not appear to be significantly enriched in ST2. These results are more consistent with ST2 originating from a compositionally distinct mantle source than the aqueous alteration of basalts. Lastly, we delineate chemically striking regions to be analyzed with data from other missions. We also examine a Tharsis region marked by the enrichment of Cl and depletion of Fe and Si, and find it to overlap significantly with a radar stealth region. Surface dust observed at the two rover sites mixed with and indurated by Ca-bearing sulfate salts would be a reasonable chemical and physical analog to meter-scale depths. The sulfates may have been produced by regional-scale activity of ground-ice driven brines. <br/> <br/>Description: Two chapters have been published already. However, following Mira Basara's (mb327@cornell.edu) instruction item 5 (see below), I did not check the "has been published previously" box. 5) Fill out the form. PLEASE NOTE: The Graduate Office asks that you do not check the box "The item has been published or publicly distributed before" even if you paper was printed or published in the past. Fri, 03 Oct 2008 15:56:30 GMT http://hdl.handle.net/1813/11425 Title: The Krishna Temple Complex, Hampi: An Exploration of its identity as a Medieval temple in the contemporary context <br/> <br/>Authors: Krishna, Ashima <br/> <br/>Abstract: Hindu temples in India have been in abundance for centuries. However, many have lost their use over time. They lie vacant and unused on vast tracts of land across the Indian subcontinent, in a time when financial resources for the provision of amenities to serve the local community are hard to come by. In the case of Hampi, this strain is felt not only by the community inhabiting the area, but the tourism sector as well. Hampi's immense significance as a unique Medieval-city in the Indian subcontinent has increased tourist influx into the region, and added pressure on authorities to provide for amenities and facilities that can sustain the tourism industry. The site comprises near-intact Medieval structures, ruins in stone and archaeologically sensitive open land, making facilitation of provision for tourists extremely difficult. This raises the possibility of reusing an existing temple structure to cater to some of these needs, akin to the Virupaksha Temple Complex and the Hampi Bazaar. But can it be done? There is a significant absence of research on possibilities of reusing a Hindu Temple. A major reason for this gap in scholarship has been due to the nature of the religion of Hinduism and its adherents. Communal and political forces over time have consistently viewed all Hindu temples are cultural patrimony of the people, despite legal ownership resting with the Government of India. In addition, a Hindu temple is complex, similar to the religion. The various Vedic rules of construction that are employed for such a structure cannot be divorced from the temple, even if it loses its liturgical use by the loss of its idol. Tampering with the spatial characteristics of a temple would be falsifying history. However, legal and religious associations of the main temple do allow for certain uses. The other parts of the temple complex can similarly be put to uses that are sensitive to the existing historic fabric of the temple complex. However this kind of a phenomenon is highly dependent on the regionality of belief and geography of thought. Other temples do not have the same location or the same circumstances as the Krishna Temple, and therefore reactions to such an endeavor may vary according to the surrounding community and their thought, their belief system. The Krishna Temple is one example out of many. It has prime location, its community has a need for space, it has immense historical value, and it caters to a large Hindu sect, making it an ideal candidate for reuse. This reuse project is a small step in the (right) direction. Only future will determine if it is a success or not. <br/> <br/>Description: Masters Thesis in Historic Preservation Planning Thu, 02 Oct 2008 12:18:07 GMT http://hdl.handle.net/1813/11423 Title: GASTROINTESTINAL BACTERIAL SYMBIONTS: REPRODUCTIVE STRATEGY AND COMMUNITY STRUCTURE <br/> <br/>Authors: Ward, Rebekah <br/> <br/>Abstract: The aim of this thesis is to describe symbiotic gastrointestinal bacterial populations in relation to their environment, both at the community and cellular level, in order to advance the field of microbial ecology. Two different levels of relations are examined: in bacterial populations as they undergo differentiation, and in bacterial symbiotic communities in relations with a host. Bacterial populations routinely collaborate in order to fully differentiate in response to environmental stress. The literature review herein describes the current state of knowledge about bacterial programmed cell death during differentiation. This study found that programmed lysis of the Low G+C Gram positive bacterial symbiont Epulopisciumoccurs after marked DNA replication in the terminally differentiated mother cell, as well as the expected replication in developing offspring cells. This energetically expensive process sustains the large metabolically active cell and may allow nutrient storage in the form of DNA for later use by the offspring or host. The close relative of Epulopiscium, Metabacterium polyspora, has different DNA dynamicsand reproduces through the formation of multiple dormant endospores. In model systems DNA replication is blocked after induction of sporulation, In contrast, M. polysporareplicates DNA inside developing forespores. This may allow M. polysporato modulate the number of forespores produced based on local nutrient availability within the gastrointestinal tract of its host. Both Epulopiscium and M. polysporaappear to have evolved reproductive strategies and related DNA replication dynamics that are suited to their particular relationship with the host. Studies of the gastrointestinal microbiota of the coral reef fish Pomacanthus sexstriatus also illustrate the ability of organisms to shape and be shaped by their environment. The unusual prevalence of sulfate reducing bacteria in this community could aid host digestion of a wider range of algae, including those that use sulfonated carbohydrates as a defense against predation. This ability may have an impact on larger coral reef ecology, promoting coral reef resilience by controlling fast-growing algal populations. In summary, investigations into these bacterial populations and communities provide data that can only be explained when bacteria are placed within the context of their environment and evolutionary history. Wed, 01 Oct 2008 14:52:53 GMT