Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 218-235). / 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.

Bibliography: leaves 170-189. This thesis looks at aphid feeding determinants by type and location. It examines the role of leaf surface chemicals in the discrimination of host plants and the deterrent effect of catechin and its oxidative condensation products.

Thesis (M. Med. Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 65-72).

published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

Myocardial ischemia-reperfusion (I/R) injury is an important health concern in myocardial infarction and situations such as angioplasty and cardiac surgeries. Therefore, patients and physicians need therapeutic interventions that are applicable at the time of surgery. Flavonoids and ascorbate (vitamin C) are known for their antioxidant activity and may be involved in the currently known health benefits of plant based foods and drinks. The objectives of this study were to 1) determine the extent to which ascorbate or catechin alone at levels which could be in blood after dietary supplementation, can protect myocardial tissue in the reperfusion phase of I/R injury, and 2) evaluate the possible cooperative or synergistic protective effect of ascorbate and catechin when given together. Isolated rat hearts (n=48) were perfused in the retrograde mode with modified Krebs-Henseleit buffer, and following the induction of 30 min global ischemia, ascorbate (150 µM) and/or catechin (5 µM) were added directly into the perfusate during 90 min reperfusion. To determine the histopathological features, hematoxylin and eosin (H&E) stain was used in one heart per condition; while to assess the biochemical analysis, the heart tissues were assessed for apoptosis (caspase-3 activity), oxidative stress (thiobarbituric acid reactive substances (TBARS) and total malondialdehyde (MDA) levels), and redox status (reduced and oxidized glutathione tissue levels). A comparison of IR hearts with two controls, sham (perfused for a 15 min stabilization period) and continuous perfusion (perfused for 135 min), showed in most but not all measurements that this was a suitable model of IR injury. The treatment experiments showed that 150 µM ascorbate protected the heart against lipid peroxidation and cell apoptosis by 100%, while 5 µM catechin protected by 67% and 90% respectively. No cooperative protective effect could be observed when ascorbate and catechin were used together. None of the treatments significantly affected either reduced or oxidized glutathione levels. In conclusion, this study showed strong protection by ascorbate, which could be used in clinically relevant situations, and is the first to report the protection by catechin at this dose under conditions of myocardial ischemia-reperfusion injury.

Bibliography: leaves 170-189. / xi, 189 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis looks at aphid feeding determinants by type and location. It examines the role of leaf surface chemicals in the discrimination of host plants and the deterrent effect of catechin and its oxidative condensation products. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1992

Thesis PlanA (M.S.)--University of Wisconsin--Stout, 2008. / Includes bibliographical references.

Thesis (M.Med.Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 65-72). Also available in print.

Thesis PlanA (M.S.)--University of Wisconsin--Stout, 2006. / Includes bibliographical references.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The aim of this study was to evaluate the efficacy of the flavonoid epigallocatechin-3-gallate (EGCG) in concentrations of 0.5%, 1% and 2% as an antimicrobial solution in artificially carious dentin, with 2% chlorhexidine and 0.9% saline solution as controls. Twenty-five slabs of human dentin (4 mm x 4 mm) were immersed for five days in Brain Heart Infusion broth (BHI-broth) inoculated at first day with Streptococcus mutans UA159 (Batch Culture Model). On the fifth day of the experiment, the blocks were randomly divided into five groups: group I - negative control - 0.9% saline solution, group II - positive control - 2% chlorhexidine, group III - 0.5% EGCG, group IV - 1% EGCG, group V - 2% EGCG. Each slab was subjected to 15 Âl of the tested solution for 60 seconds. After treatments, artificially carious dentin was removed from the dentin slabs and analyzed by counting colony forming units (CFUs). All experiments were performed in triplicate and the data obtained in CFUs mean values converted to log base-10. The statistical tests used were analysis of variance (ANOVA) followed by Tukey test. There was no statistical difference between EGCG concentrations and saline (p > 0.05). Furthermore, there is no statistical difference between EGCG concentrations (p > 0.05). However, there was statistically significant difference between chlorhexidine and the other groups (p < 0.05). From the data obtained in this study, is possible to conclude that the substance tested is not effective on elimination of pathogen S. mutans when used in a concentration of 0.5%, 1% and 2% in artificially carious dentin. / O objetivo do presente estudo foi avaliar a eficÃcia do flavonÃide epigalocatequina-3-galato (EGCG) nas concentraÃÃes de 0,5%, 1% e 2% como soluÃÃo antimicrobiana em dentina artificialmente cariada, tendo a clorexidina 2% e a soluÃÃo salina 0,9% como controles. Vinte e cinco blocos de dentina humana (4 mm x 4 mm) foram imersos por cinco dias em BHI-caldo inoculado com Streptococcus mutans UA159 no primeiro dia do experimento. No quinto dia do experimento, os blocos foram aleatoriamente distribuÃdos em cinco grupos: grupo I â controle negativo â soluÃÃo salina 0,9%; grupo II â controle positivo â clorexidina 2%; grupo III â EGCG 0,5%; grupo IV â EGCG 1%; grupo V - EGCG 2%. Cada bloco recebeu tratamento de 15 Âl da soluÃÃo testada, que permaneceu em contato com o bloco por 60 segundos. ApÃs os tratamentos, amostras dentinÃrias foram removidas com emprego de lÃmina de bisturi e foram analisadas a partir da contagem de UFCs (unidades formadoras de colÃnias). Os experimentos foram realizados em triplicata e os dados, obtidos em UFCs foram convertidos em log base-10. Os testes estatÃsticos empregados foram anÃlise de variÃncia (ANOVA), seguida de Teste de Tukey. NÃo houve diferenÃa estatÃstica entre as concentraÃÃes de EGCG empregadas e a soluÃÃo salina (p > 0,05). AlÃm disso, nÃo houve diferenÃa estatÃstica entre as concentraÃÃes de EGCG (p > 0,05). No entanto, houve diferenÃa estatisticamente significativa entre a clorexidina e os demais grupos (p < 0,05). Conclui-se, a partir dos dados encontrados, que a substÃncia investigada nÃo deve ser empregada em preparos cavitÃrios com a finalidade de eliminaÃÃo de patÃgenos, visto que nÃo se mostrou eficaz como antimicrobiano nas concentraÃÃes testadas.