Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains ix, 38 p. : ill. Includes abstract. Includes bibliographical references.

The overall objective of this thesis was to test the hypothesis that through developmental programming maternal overnutrition-induced metabolic derangements in the offspring could be offset by supplementing the maternal diet with green tea epigallocatechin gallate (GTEG). The obesogenic diet was a high-fat (HF, 30%) diet. Female Sprague-Dawley rats were fed the HF, low-fat (LF, 7%) or HF diet containing 0.75% or 1.0% GTEG (GT1, GT2) from before conception and throughout gestation and lactation. Both doses of GTEG significantly improved metabolic control of the HF-fed lactating dams. The weaned male pups received the HF, GT1 or GT2 diet forming 6 dam/pup groups: LF/HF, HF/HF, HF/GT1, HF/GT2, GT1/HF and GT2/HF. At wk 13 they had similar weight but insulin resistance index (IRI), serum non-esterified fatty acid (NEFA) and liver triglyceride of rats born to GTEG dams was 57, 23 and 26% lower and accompanied by improved gene/protein expressions related to lipid and glucose metabolism compared to HF/HF rats (P < 0.05). Although the HF/GT1 and HF/GT2 rats had lower serum NEFA, their serum insulin and IRI remained comparable with the HF/HF rats. To determine if there is a critical time period for the actions of GTEG, in the second experiment female rats were fed the LF, HF, or GT1 diet prior to conception and throughout gestation. During lactation, half of the dams had their diet switched from HF to GT1 and vice versa. Pups were weaned to the HF or LF diet, forming the LF/LF/LF, LF/LF/HF, HF/HF/LF, HF/HF/HF, HF/GT1/LF, HF/GT1/HF, GT1/GT1/LF, GT1/GT1/HF, GT1/HF/LF and GT1/HF/HF groups. Metabolic controls of dams given GT1 during gestation or lactation were improved compared with the HF/HF dams (P < 0.05). Three-way ANOVA revealed that 22 wk old offspring born to dams fed the HF diet during gestation had higher serum and muscle triglyceride (TG) concentration and lower ferric reducing ability of plasma (FRAP) (P < 0.05), all of which were reversed by supplementing GT1 to the gestational diet. Oral glucose tolerance at wk 15 was improved in those offspring born to dams given GT1 supplementation during lactation (P < 0.05). The increased serum NEFA concentration and IRI in offspring of dams fed the HF diet during gestation or lactation were reversible upon GT1 supplementation during either time period (P < 0.05). These rats (HF/GT1/HF, GT1/GT1/HF and GT1/HF/HF) had similar level of hepatic insulin receptor gene expression as well as protein abundance for muscle glucose transporter 4 and hepatic sterol regulatory element binding protein-1c but lower protein mass for hepatic glucose-6-phosphatase (P < 0.05) compared with the LF/LF/HF rats. Hence, maternal overnutrition-induced metabolic derangements in male offspring are reversible through supplementing GTEG to the maternal diet during gestation or lactation and this approach is more effective than giving GTEG to offspring born to overnourished mothers. Offspring metabolism could be programmed via manipulations of the maternal diet. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Thesis (M.Med.Sc.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 44-57). Also available in print.

Made available in DSpace on 2014-06-11T19:24:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-11-23Bitstream added on 2014-06-13T20:51:26Z : No. of bitstreams: 1 fonseca_bm_me_sjc.pdf: 775997 bytes, checksum: e77eb2f75ac56e60c212e110b913bb06 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi avaliar a interface adesiva de amostras de dentina bovina / adesivo e resina variando as estratégias adesivas e o tempo de armazenamento. Foram selecionados 80 incisivos bovinos, limpos e seccionados 2,0 mm além da junção amelocementária, desgaste da superfície vestibular do esmalte, com exposição de uma área plana de dentina, a qual foi submetida a diferentes protocolos adesivos. Aleatoriamente, as amostras foram divididas em 4 grupos (n= 20), submetidos às estratégias adesivas: SB – controle: sistema adesivo Adper Single Bond 2 aplicado segundo instruções do fabricante; CLX – clorexidina: aplicação de solução de digluconato de clorexidina 0,2% previamente a aplicação do sistema adesivo semelhante ao SB; EGCG – EGCG10: aplicação da solução em gel de EGCG 10μM – principal componente ativo do chá verde – por 30 s previamente a aplicação do sistema adesivo semelhante ao SB; e CV – solução aquosa de chá verde: aplicação do chá verde – preparado após infusão da erva acondicionada em sachê – previamente a aplicação do sistema adesivo semelhante ao SB. Em todos os grupos foi aplicada resina composta (RC) Amelogen Plus com o auxílio de matriz de silicone, com fotopolimerização por 20 s cada incremento. Posteriormente, os grupos foram redivididos em dois subgrupos (n= 10) de acordo com o tempo de armazenamento em água destilada por 24 h e 6 meses, a 37ºC em estufa bacteriológica. Em seguida, todos os corpos-de-prova foram seccionados no sentido mésio-distal e cérvico-incisal em cortes paralelos de espessura aproximada de 0,8 mm2 em cortadeira Labcut (Extec Technologies – EUA) com refrigeração em baixa velocidade. Desta forma, foram obtidos em média 9 palitos por dente, sendo cada... / The aim of this study was evaluate the adhesive interface of bovine dentin samples / adhesive and resin varying adhesive strategies and time of storage. Eighty bovine incisors were selected, cleaned and sectioned 2.0 mm beyond the cementoenamel junction; the labial surface of the enamel was worn to obtain a flat area of exposed dentin. The dentin was subjected to different adhesives protocols. Samples were randomly divided into 4 groups (n = 20), according to the adhesive strategies: SB - control: Adper Single Bond 2 (SB) system was applied according to manufacturer's instructions; CHX - chlorhexidine: application of 0.2% chlorhexidine gluconate solution prior to adhesive system similar to SB; EGCG - EGCG10: application 10 μM EGCG gel - the main active component of green tea - for 30 s prior to application of the adhesive system similar to SB; and GT - aqueous green tea: application of green tea - prepared after infusion of the herb sachet - prior to application of the adhesive system similar to SB. The composite resin Amelogen Plus was applied in all groups with aid of silicone matrix, and lightcured for 20 s. Subsequently, groups were re-divided into two subgroups (n = 10) in accordance with the time of storage in distilled water, for 24h or 6 months at 37°. Specimens were sectioned to obtain parallel cuts and beams of approximately 0.8 mm2. Cut procedure was performed in Labcut cutting machine (Extec Technologies - USA) at low speed with cooling. Nine beams per tooth were obtained. Each beam was attached with cyanoacrylate glue to a device prepared for submission to the microtensile test, using a universal testing machine (DL-1000, EMIC, Pinhais-PR-Brazil) with 10 kgf load and speed of... (Complete abstract click electronic access below)

Theanine is a free, non-protein amino acid found in Camellia sinensis (tea) leaves. It is the main amino acid component in tea and contributes 1 to 2% of the dry weight of tea leaves. The content of amino acids is a key green tea quality parameter. High grade teas contain high amounts of theanine. It is responsible for the sweet, brothy umami taste of green tea. To date there is no international standard method for the analysis of theanine in tea samples. Several methods with different advantages and disadvantages have been reported but most of them are unsuitable for routine quality control analysis in commercial tea samples. In this study, a high performance liquid chromatography (HPLC) method with evaporative light scattering detection for the determination of theanine in tea samples has been developed. Chromatographic separation of theanine was achieved by reverse phase HPLC using a phenyl-hexyl column and isocratic water elution within 8 minutes. The method requires no sample derivatization and includes simple sample clean-up. Applying the same chromatographic conditions to a widely available C18 column, separation of theanine was achieved within 10 minutes. The successful application of the C18 column renders this method widely applicable. The method is linear over several orders of magnitude and the LOD are 11.53 and 10.83 μg/ml and the LOQ are 39.44 and 35.10 μg/ml for the phenyl-hexyl and C18 column, respectively. Simple but effective sample preparation and polyvinylpolypyrrolidone pre-treatment, along with the short analysis time facilitates high sample throughput (~40 samples can be prepared in an 8 hour day with overnight analysis by HPLCELSD). The method is selective, precise, accurate and practical for the quantification of theanine in tea extracts and was successfully used to determine theanine content in a variety of tea samples. The sensitivity and simplicity of this method renders it suitable for use in routine theanine analysis in quality control laboratories. Green tea, a simple refreshing beverage, has been believed to have therapeutic uses for centuries. Scientists have recognized that the wide range of physiological functions of green tea is due to the presence of catechins. An increasing body of evidence is showing that methylated forms of catechins have potent inhibitory activities to allergies. In addition to the methylated catechins, another relative novel group of catechins exists, namely digallated catechins. The medicinal value of these compounds is not yet known, but it is reasonable to speculate that the antioxidant capacity of digallated catechins will be superior to that of epigallocatechin gallate due to the 3 additional hydroxyl groups provided by the second gallic acid moiety. In this study reverse phase UPLC/ESI-MS/MS was effectively applied to investigate the presence of digallated and methylated catechins in crude tea extract. Low abundance catechins (-)-epigallocatechin-(O-3”-methyl) gallate ([M + H]+, m/z 473) and (-)-epicatechin-3-(O-3”-methyl) gallate ([M + H]+, m/z 457) were successfully detected at 31.9 and 37.5 minutes, respectively. The 2 digallated catechins investigated could not be detected, possibly due to being present at concentrations below the limit of detection. Compared to conventional HPLC/ESI-MS/MS, increased resolution and sensitivity, 80% less use of solvent and significantly reduced analysis times were observed. / Dissertation (MSc)--University of Pretoria, 2009. / Biochemistry / unrestricted

Green tea contains high concentrations of polyphenolic compounds known as catechins. Studies in animal models suggest several potential mechanisms for specific metabolic effects at rest and during exercise, including improved glycemic control, altered activity of several glucose transporter proteins and improved endurance capacity. In humans, green tea extract (GTE) supplementation has been associated with improved glycemic control under resting conditions and increased fat oxidation during exercise. This dissertation examined the potential interactive effects of GTE supplementation and exercise on metabolism in humans with a focus on glycemic control. In Study 1, we demonstrated that GTE increased lipolysis and reduced heart rate during steady-state exercise in recreationally active men. Although substrate oxidation was not affected, GTE appeared to lower postprandial glucose under resting conditions. We hypothesized that the effects of GTE on exercise metabolism and glycemic control would be more apparent in humans with reduced exercise tolerance and impaired glucose tolerance. Thus, in Study 2, we examined the effects of GTE in sedentary overweight men. There were no differences in any metabolic or physiological responses during exercise; however, following exercise, GTE supplementation reduced [glucose] and insulinemia in response to an oral glucose load. Based on the findings of Study 2, the aim of Study 3 was to elucidate potential mechanisms for the alterations in glycemic response. Through the use of a dual-glucose tracer method, we demonstrated that GTE did not affect the rate of appearance of glucose in plasma in sedentary men; however, GTE supplementation allowed for the same glucose clearance rate despite a reduced insulinemia. We also observed lower carbohydrate oxidation during exercise with GTE. These findings suggest that GTE has an insulin-sensitizing effect during recovery from exercise, possibly due to enhanced glucose transporter activity; however, this hypothesis warrants further investigation in humans. / Dissertation / Doctor of Science (PhD) / Tea is one of the most popular beverages in the world. Compared to other teas, green tea has a greater abundance of catechins, compounds that have been associated with health benefits particularly related to the metabolism of sugars and fats. This unique property of green tea could partly explain its longstanding medicinal role in some Asian cultures. Extensive research on green tea has increased its popularity over the past three decades. Studies involving both humans and other animals have shown improvements in weight control and glycemic control. In response to these findings green tea is often touted as having “anti-obesity” and anti-diabetic” properties. This dissertation examined the interaction between green tea extract supplementation and exercise on metabolism with a particular focus on blood sugar control. We observed that supplementation with green tea extract improved the response to sugar ingested after exercise. This finding has important implications for improving the control of ingested sugar in humans.

published_or_final_version / Pharmacology / Doctoral / Doctor of Philosophy