Female students are found to have much higher English achievement and most of the learning process parameters, including Formal Motivation Intensity, opinion on MOI (medium of instruction) in English lessons, attitude of interest, attitude of essential, attitude towards bilingualism, motivation for learning English, Instrumental Orientation and Communicative Orientation. / Girls out-performed boys in reading at the age of 15 in all 43 countries included in a credible study by the Organization for Economic Cooperation and Development (OECD) and UNESCO. Male underachievement generally alarms educators. In Hong Kong, proficiency in English language more or less assures a better future, higher academic path and job security. Is there any sex difference in English language achievement in secondary three? If so, what are the factors and causes in the learning process responsible for this difference? / In accordance with the above findings, it is suggested that more effort should be put to stimulate boys to establish their learning goals, to arouse their interest and develop positive attitudes towards learning English; to activate their intrinsic motivation for learning English. Interventions at policy level are needed. / In the causal relations between English achievement and learning process parameters, female and male students show significant differences. The causal path from Motivation to S3 English Achievement is 0.43 (t-value = 34.52) in females and 0.37 (t-value = 28.65) in males. It means when controlling Motivation, females can have higher achievement in S3 English. The causal path from Instrumental Orientation to Motivation is 0.67 (t-value=31.80) in females and 0.79 (t-value=29.33) in males. The causal path from Communicative Orientation to Motivation is 0.40 (t-value=20.32) in females and 0.27 (t-value=10.72) in males. It also means that when controlling Instrumental Orientation, male students can have higher Motivation of learning English. If Communicative Orientation is controlled, female students can have higher Motivation of learning English. / The present study aims at exploring the sex differences in English learning achievement, and in the learning process parameters in secondary 3. Gardner's socio-educational model serves as the theoretical model for multi-causal path analysis. The English learning achievement is related to motivation and then to learning orientations. According to local researches about English learning, Instrumental Orientation is added to Gardner's model for multi-group comparison. / The total effect from Instrumental Orientation to S3 English achievement is 0.13 (t-value=11.69) in females and 0.05 (t-value=4.24) in males. Total effect from Communicative Orientation to S3 English achievement is 0.08 (t-value=9.68) in females, and 0.02 (t-value=3.87) in males. / Fung Kam Yin. / "November 2006." / Adviser: Tsang Wing Kwong. / Source: Dissertation Abstracts International, Volume: 68-08, Section: A, page: 3277. / Thesis (Ed.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 357-378). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

錢華. / 顯微膠片卷端, 作者名誤作"HUA, Qian" / 呈交日期: 2006年11月. / 論文(哲學博士)--香港中文大學, 2007. / 參考文獻(p. 183-189). / Xian wei jiao pian juan duan, zuo zhe ming wu zuo "HUA, Qian" / Cheng jiao ri qi: 2006 nian 11 yue. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in Chinese and English. / Lun wen (zhe xue bo shi)--Xianggang Zhong wen da xue, 2007. / Can kao wen xian (p. 183-189). / Qian Hua.

2. A modified model of heart-arterial system was proposed for describing the timing of the second heart sound as a result of the heart-arterial interaction. Simulation results suggest that RS2 bears a significant negative correlation with both SBP and DBP as heart rate, cardiac contractility and peripheral resistance varies. The hypothesis was supported by the experimental data. To our knowledge, it is the first study describing the relation of the timing of S2 to BP by both the model-based study and experimental data. / 3. As a preliminary study, a linear predication model using RS2 with a novel calibration scheme was proposed for BP estimation and it has been evaluated in clinical test on 85 volunteers including 18 hypertensives. The results indicate that the approach has the potential to achieve the accuracy required for medical diagnosis. / Cuffless BP measurement has been proposed as a new concept in recent years to realize the continuous monitoring of BP. This research focuses on the investigation of cuffless BP monitoring technique using heart sound information. Specifically, the thesis proposes a new cuffless technique based on the timing of the second heart sound (S2), which will enable a novel wearable design of BP monitor, for instance, a multifunctional electronic stethoscope. / Finally, based on the findings on both theoretical and experimental studies, a linear prediction model with a novel calibration scheme has been proposed to estimate the BP using 1/RS2. The proposed method was evaluated in a clinical test on 85 volunteers aged 40+/-13 years, including 18 hypertensives. The average of BP measured by simultaneous ausculatory and oscillometric approaches was used as a reference. The results of clinical test shows that the RS2 based approach can estimate SBP and DBP within the 2.1+/-7.4 mmHg and 0.8+/-6.6 mmHg of the reference respectively, indicating the approach has the potential to achieve the accuracy required for medical diagnosis according to AAMI standard (mean error within +/-5mmHg and SD less than 8mmHg) and BHS protocol. / First, a mathematical model has been developed to investigate the effects of aortic BP on the aortic component (A2) in S2 produced by the vibration of the closed aortic valve. The nonlinear elasticity of aortic wall has been introduced to the model, reflecting the nature of aortic wall tissue and extending the model to the applications involving wide BP variations. The results of simulation show that the fundamental frequency and amplitude of A2 increases as aortic systolic blood pressure (SBP) is elevated, which is able to explain the 'accentuated S2' usually heard in the hypertensives. Nevertheless, the possibility of BP measurement using spectral information of externally recorded heart sounds still needs a careful examination because the frequency characteristics tends to be blurred during sound transmission. / Hypertension, known as 'a silent killer', is an important public health challenge, afflicting approximately 1 billion adults around the world. The monitoring of blood pressure (BP) is vitally important in order to identify hypertension and treat it earlier before serious health problems are developed. The conventional BP measurement provides only intermittent BP and causes circulatory interference if the cuff is inflated frequently. There is an urgent need to develop new devices which are fully wearable and unobtrusive for noninvasive and continuous monitoring of arterial BP in daily life. / Second, a modified model of heart-arterial system has been proposed in this thesis for describing the timing of aortic valve closure as a result of heart-arterial interaction. A timing parameter, RS2, was defined as the time delay from the peak of ECG R wave to the onset of S2. The study has investigated the relation between RS2 and aortic BP under varying peripheral resistance, arterial compliance, heart rate, cardiac contractility and preload. Based on the simulation results of parametric analysis, it is hypothesized that RS2 bears a significant negative correlation with both SBP and diastolic blood pressure (DBP) as the peripheral resistance, heart rate or cardiac contractility varies. / Third, in order to verify the findings of the model-based study, three experiments were carried out to explore the relationship between RS2 and BP. The alterations of RS2 in the dynamic-exercise experiments are mainly attributable to the interactive effect of the changes in heart rate, cardiac contractility and peripheral resistance, and the effect of heart rate is dominant. In two dynamic-exercise experiments, the timing parameter, RS2, exhibited a close inverse correlation with SBP (r =0.892 and r =0.845, p<0.05 in both experiments) and a moderate inverse correlation with diastolic blood pressure (DBP) (r = 0.687, p<0.05 and r =0.660, p>0.05). The correlations are comparable to those of PTT-based parameters. However, due to the restricted range of the BP variation, there was no significant correlation observed in long-term rest monitoring experiment. Moreover, the standard deviation (SD) of the errors for SBP and DBP estimated by linear fitting of 1/RS2 is close to that of PTT-based estimation. The results also suggest that the ability of RS2 on BP estimation is as good as that of the PTT based parameters. / To summarize, the original contributions of the thesis are: 1. By the introduction of the nonlinear elasticity of aortic wall, a mathematical model for the vibration of the closed aortic valve was improved and extended to the applications involving wide variations of BP To my knowledge, this represents the first study to look into the effects of aortic BP on the frequency characteristic of S2 from the theoretical point of view. / Zhang Xin-Yu. / "September 2006." / Adviser: Yuan-Ting Zhang. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6125. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

In addition, we investigated the cytotoxic effect of a widely used chemotherapeutic agent 5Fu on laryngeal squamous cell cancer cell lines and evaluated the role of p53 in 5Fu treatment. We found that the apoptosis and G1/S cell arrest mediated by 5Fu in laryngeal cancers is p53-independent but p21 WAF1/CIP1-dependent. We further demonstrated the effect of 5Fu on HPV16-associated laryngeal cancer cells. Using cytotoxicity assay and Annexin V staining, we proved that 5Fu induces apoptosis in all of the transfected cells in a dose- and time-dependent manner, suggesting that the process was not prevented by HPV16 E6 or E7. 5Fu induced the accumulation of active pRb and cyclin dependent kinase inhibitor p21WAF1/CIP1 together with an increase in Bak and Bax expression and a decrease in Bcl-2 levels in all the transfected cells. In addition, G1/S phase cell cycle arrest was associated with the antiproliferation activity of 5Fu in all cell lines. Through RT-PCR, 5Fu also presented some effects on the E6 and E7 oncoproteins of HPV16 in transfected UMSCC 12 cells. / Our results suggest that HPV16 E6 and E7 oncoproteins do not prevent 5Fu medicated apoptosis and G1/S cell arrest in laryngeal cancers. The anti-cancer effect of 5Fu is probably decided by the level of p21 WAF1/CIP1 while the sensitivity of laryngeal cancer cells responded to 5Fu treatment is associated with the increase of Bak or/and the decrease in Bcl-2, not with the HPV16 viral proteins and p53 status. 5Fu also presented some effects on the E6 and E7 oncoproteins of HPV16 in laryngeal cancer. However, the anti-viral effect of 5Fu still needs further investigation. / Our study indicated that (1) the evasion of apoptosis mediated by HPV16 E6 and E7 plays a critical role in laryngeal carcinogenesis; (2) HPV16 E6 or E7 plays an important role in regulating the expression of Bak, Bax and Bcl-2; (3) The degradation of Bak by HPV16 E6 is not caused by interacting with the promoter of Bak; (4) The induction of Bcl-2 is mediated through HPV16 E7; (5) HPV16 transfection does not interfere with the apoptosis and cell cycle arrest mediated by 5Fu in human laryngeal squamous cancer cells. / There is a growing body of evidence that human papillomavirus type 16 (HPV16) is involved in the development of human laryngeal cancer, especially in Chinese population. The two oncoproteins, HPV16 E6 and E7 that target host cell tumor suppressor proteins p53 and Rb respectively, may generate antiapoptotic effects and induce cell immortalization. However, the effect of both oncoproteins on apoptosis in laryngeal cancers is not completely clear. In this study, we demonstrated the possible mechanism of high risk HPV16 in laryngeal carcinogenesis and evaluated the effect of 5Fu on HPV16-positive laryngeal cancer cells. / We employed two human laryngeal cancer cell lines---UMSCC12 (with truncated p53) and UMSCC11A (with mutant but functional p53) in this study. These two cell lines were stably transfected with HPV16 E6, E7 or empty vector, pcDNA3.1, which provided a good foundation for further study on the carcinogenic mechanism of HPV16 E6 or E7 in human laryngeal cancers. Through Annexin V staining and protein stability assay, we found that the transfection of HPV16 E6 and E7 induced fewer spontaneous apoptosis in both UMSCC11A and UMSCC12 cells accompanied with enhanced protein stability of Bcl-2 and increased protein degradation of Bak. Similar results were obtained when E6- and E7-transfected cells exposed to apoptosis stimuli---TNF-alpha/CHX. These results indicate that stable transfection of E6 and E7 in human laryngeal cancer cells on one hand shortened the half-life of Bak protein, and on the other hand, enhanced the steady-state levels of Bcl-2 protein. In order to gain insight into the role of Bak and Bcl-2 in regulating apoptosis in HPV-associated laryngeal cancer cells, we performed transient transfection of Bcl-2 into E6- and E7-transfected cells. It is found that HPV16 E7 statistically enhanced the expression of Bcl-2 in laryngeal cancer, indicating that the induction of Bcl-2 require the transfection of HPV16 E7. Furthermore, Luciferase assay was performed to investigate whether the viral proteins E6 and E7 altered the stability of Bak through interaction with the promoter of Bak. Negative results were obtained, suggesting that E6 or E7 do not alter the transcription activity of Bak, indicating the degradation of Bak by E6 or E7 may be mediated through other mechanisms. / Liu Han-ching. / "August 2006." / Advisers: C. A. van Hasselt; George G. Chen. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1569. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 245-274). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

In the studies about ovarian cancer cells, basal iNOS expression in the chemosensitive OV2008 cells was significantly higher than in the chemoresistant C13* cells. Cisplatin further increased iNOS expression in OV2008 cells, but had no effect in C13* cells. Furthermore, cisplatin dramatically reduced the expression levels of eNOS and nNOS, but again only in OV2008 cells. The data suggest that failure of cisplatin to upregulate iNOS and downregulate eNOS and nNOS in C13* cells could be an etiological factor in chemoresistance. Addition of exogenous NO at high levels, using SNAP, significantly increased p53 protein levels and caused apoptosis in both cell types. Specific iNOS inhibitor (1400W) partially blocked the pro-apoptotic effects of cisplatin in OV2008 cells, suggesting involvement of iNOS in cisplatin-induced apoptosis. However, blocking of all three isoforms of NOS with NG-amino-L-arginine in C13* cells dramatically changed these cells from chemoresistant to chemosensitive, greatly potentiating the pro-apoptotic effects of cisplatin. / Inhibition of Src-kinase activity reduces DNA synthesis in ovarian cancer cells. In an in vitro experiment, Src phosphorylated PKG on a tyrosine residue and PKG, presumable via serine-phosphorylation of Src, enhanced Src auto(tyrosine)phosphorylation. In ovarian cancer cells, inhibition of basal PKG activity with DT-2 decreased both basal and EGF-stimulated Src kinase activation and DNA synthesis. The data suggest that PKG at basal activity, is necessary for both basal and growth factor-stimulated Src kinase activation and enhanced DNA synthesis in human ovarian cancer cells. / The novel role of sGC/cGMP/PKG pathway on stimulating cell proliferation, potentially via interaction with the Src kinase pathway in human ovarian cancer cells, was demonstrated. ODQ dramatically reduced DNA synthesis rates, suggesting that basal sGC activity and basal cGMP levels are needed for ovarian cancer cell proliferation. DT-2 also reduced cell proliferation, suggesting the direct involvement of PKG. ANP and BNP had no effect on cell proliferation, suggesting that further activation of cGMP/PKG pathway above basal levels does not further enhance cell proliferation. / The present study also demonstrated that elevating cGMP slightly above the basal levels further protects pancreatic islet cells against spontaneous onset of apoptosis. The results showed that natriuretic peptides (both ANP and BNP) and low-level NO (i.e. physiological levels) as supply by NO donor, S-nitroso-N-acetylpenicilamine (SNAP) further prevented spontaneous apoptosis in pancreatic islets after isolation, whereas NO at high concentrations (i.e. pathological levels) promoted apoptosis in pancreatic islet cells. The commonly-used PKG inhibitor KT5823 and the newly-developed specific PKG inhibitor DT-2 completely prevented anti-apoptosic effect of ANP, suggesting the direct involvement of PKG in protection against spontaneous apoptosis. / The present study demonstrated that basal activity of sGC/cGMP/PKG signaling pathway is essential for partially limiting spontaneous apoptosis in pancreatic islet cells. The sGC inhibitor ODQ caused induction of apoptosis, which was completely blocked by co-treatment with ANP or BNP, agents that elevate cGMP via pGC, bypassing the ODQ block. Co-treatment with 8-Br-cGMP, a direct activator of PKG also completely prevented ODQ-induced apoptosis in islets. / Leung Lai-han. / "July 2006." / Adviser: Ronald Ray Fiscus. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1483. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 175-191). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

and senkyunolide A were found as the three major compounds in all herbal samples investigated. In addition, great variations in both total and individual content of each of the ten main components investigated were observed in samples of different origins and those collected from a GAP developing base in the same or different years, suggesting the necessity of a thorough quality control for Rhizoma Chuanxiong. / Extraction of the main ingredients from Rhizoma Chuanxiong by supercritical fluid extraction using CO2 was investigated. An appropriate SCFE method for Chuanxiong was developed with the mild conditions for the extraction of the unstable components. The method provided a high recovery and adequate reproducibility, and may be suitable for large-scale industry extraction of Chuanxiong. / Firstly, a total of sixteen ingredients were identified from Chuanxiong by HPLC-UV-MS and HPLC-UV analyses. Among them, ten ingredients were determined to be the main components in Chuanxiong. A simple, sensitive and specific HPLC-UV method was developed, for the first time, to simultaneously qualitatively and quantitatively determine twelve ingredients, including the identified ten main ingredients, plus vanillin and tetramethylpyrazine (TMP), which although were not found in the present study, had also been reported to be present in Rhizoma Chuanxiong. The developed assay was fully validated and provided adequate accuracy and reproducibility for all compounds analyzed. It was applied successfully to simultaneously quantify all main constituents in different Chuanxiong samples. TMP and vanillin were not detected, while Z-ligustilide, coniferylferulate. / Furthermore, a comprehensive stability study was carried out for the first time with the three major components senkyunolide A, coniferylferulate, Z-ligustilide and the main ingredient 3-butylidenephthalide, in pure form or Chuanxiong extract obtained from supercritical fluid extraction using CO 2 (SCFE) under different conditions. Results showed that both sun light and elevated temperature led to degradations of these components to different extents. Owing to such thermal and light instability, post-harvest drying and processing procedures could significantly alter the chemical profile of Chuanxiong herb, and thus also need to be well controlled. / In conclusion, analytical and pharmacokinetic studies of the main chemical ingredients in Rhizoma Chuanxiong were systematically conducted. The results revealed, for the first time, that senkyunolide A, Z-ligustilide and 3-butylidenephthalide might be the primary chemical ingredients contributing to the beneficial effects of Chuanxiong. / Oral bioavailability was about 8%, 3% and 20% for senkyunolide A, Z-ligustilide and 3-butylidenephthalide, respectively. Instability in the gut mainly contributed to a low oral bioavailability of senkyunolide A. First-pass metabolism in the liver also contributed to the low oral bioavailability but to a much lower extent. For Z-ligustilide, extensive first-pass metabolism in the liver and degradation in the stomach only partly accounted for its poor oral bioavailability, while other gut factors involved are still unknown. In the case of 3-butylidenephthalide, its low oral bioavailability was attributed to extensive first-pass metabolism in both the gut and the liver. / Pharmacokinetic fates of the main ingredients in Chuanxiong SCFE extract were firstly evaluated in rats. After a single intravenous and oral administration, only senkyunolide A, Z-ligustilide and 3-butylidenephthalide were determined as the main herb related components in plasma. Coniferylferulate, although it is one of the abundant principles in the herb, was not detected in the plasma even immediately after dosing. / Pharmacokinetic profiles of senkyunolide A, Z-ligustilide and 3-butylidenephthalide were further elucidated individually in rats. All three compounds exhibited rapid absorption, extensive distribution, and rapid elimination. The pharmacokinetic profile of senkyunolide A followed a dose-independent pattern, whereas Z-ligustilide exhibited dose-dependent kinetics. 3-Butylidenephthalide underwent enterohepatic re-circulation. / Rhizoma Chuanxiong is derived from the dried rhizome of Ligusticum chuanxiong Hort. (Umbelliferae). In China, it has been widely prescribed for the treatment of cerebro- and cardio-vascular diseases for thousands of years. However, its chemical and pharmacological basis is poorly understood. In the present study, analytical methods for qualitative and quantitative determination of the main chemical components in Chuanxiong herb were developed. Furthermore, pharmacokinetic profiles of the main chemical ingredients in Chuanxiong were systematically investigated in rats for the first time. / The metabolic profiles of senkyunolide A, Z-ligustilide and 3-butylidenephthalide were investigated both in vivo and in vitro. Oxidation and hydration were found to be the main metabolic pathways for all three compounds. In addition, glutathione conjugation of senkyunolide A and Z-ligustilide also occurred in the rat. A novel metabolite 3-hydroxy-3-butylphthalide was identified as the major metabolite of 3-butylidenephthalide generated by a direct hydration, and was shown to have significantly higher plasma levels than those of the parent compound. Furthermore, the main metabolites detected in the plasma of rats administered with Chuanxiong extract were generated from senkyunolide A, Z-ligustilide and 3-butylidenephthalide. / Yan Ru. / "May 2005." / Adviser: Ge Lin. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1583. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 244-255). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Bi-directional transport studies in SimBioDASRTM and Caco-2 cells were employed to examine the transport profiles of Buph, Ligs and SenA. Apical to basolateral (A-B) transport studies of the tested compounds revealed high intestinal permeability and predicted human absorption of over 98%. Permeability ratio of B-A/A-B of Buph (0.7-1.3) and Ligs (0.8-1.2) indicated that they were transported by passive transcellular and paracellular pathways while the low B-A/A-B ratio of SenA may imply possible involvement of other transport mechanisms. One metabolite (M-1) generated from hydration of Buph was observed in Caco-2 cells and the fraction of metabolism was 12.5% (A-B). / In conclusion, Buph, Ligs and SenA were predicted to have good intestinal absorptions in human and rat. However, extensive hepatic and intestinal first-pass metabolism of Buph in rat and human were found to cause its low oral bioavailability. On the other hand, certain degree of hepatic first-pass metabolism of Ligs and SenA may account for the partial loss of drugs via oral administration to rat. Therefore, other routes of delivery, such as sublingual administration, are worth to be considered to improve the therapeutic effects of chuanxiong. / In the rat SPIP, permeability calculated from the appearance of Buph in mesenteric blood (Pblood) was 6.0+/-1.7 x 10-4 cm/s while the fraction of formation of M-1 was about 7.1%. Together with the in vitro results, it is proposed that first-pass metabolism of Buph was present in human and rat small intestine. Moreover, Ligs and SenA had high Pblood values of 4.2+/-1.2 x 10-3 cm/s and 3.8+/-2.8 x 10-3 cm/s, respectively, indicated that they were highly permeable across rat intestinal mucosa. No metabolism of Ligs was observed. But several metabolites of SenA were detected despite they were not quantified in the present study. / In vitro metabolic studies of Buph demonstrated that major metabolite M-1, which was also found in Caco-2 cells and SPIP, formed mainly in intestine and liver cytosol in rat and human. The intrinsic clearance (Vmax/Km) of Buph was extensive and similar in both organs, and its extent in human was comparable to that in rat. The sum of the estimated in vivo extraction ratio of Buph by liver (48.3%) and intestine (55.0%) was higher the loss via oral administration to rat (77%). On the other hand, several metabolites of Ligs and SenA were found in rat and human liver microsome but not in intestinal preparations. The estimated in vivo extraction ratio by liver of rat was 47.3% (Ligs) and 22.9% (SenA), respectively, which were less than the corresponding loss via oral administration to rat (Ligs: 92.2% and SenA: 97.7%), suggesting that first-pass effect other than metabolism of these two compounds in intestine also contributed to their low oral bioavailability. / Rhizoma chuanxiong is commonly prescribed orally for improving blood circulation and treating cardiovascular disorders in China. Like other traditional Chinese medicines, chuanxiong has been used for thousands of years in China but its chemical basis, pharmacological effects and pharmacokinetic fates of the active ingredients, especially absorption, are poorly understood. Recently, seventeen compounds such as 3-butylidenephthalide (Buph), Z-ligustilide (Ligs), senkyunolide A (SenA), vanillin (Vani), ferulic acid (Fera), senkyunolide I (SenI), senkyunolide H (SenH), coniferyl ferulate (ConFer), sedanolide (Sdan), riligustilide (Rili) and levistolide A (LevA) have been isolated and recognized as the main constituents of chuanxiong by our research team (Li et al., 2003). Moreover, it has been demonstrated that Buph, Ligs and SenA are bioactive components of chuanxiong for vasodilatation and anti-thromboembolism (Chan, 2005) though their oral bioavailability in rat are very low (2.3, 7.8 and 23% respectively) (Yan, 2005). Therefore, the present study aims at investigating the intestinal permeability of the major ingredients of chuanxiong and characterizing the intestinal absorption and first-pass metabolism of Buph, Ligs and SenA by in vitro Caco-2 cell monolayers, SimBioDASRTM , in situ single-pass intestinal perfusion (SPIP) in rat and in vitro metabolism using rat and human intestine and liver subcellular fractions respectively. / Using the in vitro cell monolayers of SimBioDAS RTM, the intestinal permeability of major components of chuanxiong ranged from 12.2+/-1.6 x 10-6 cm/s to 70.6+/-9.6 x 10-6 cm/s with a rank order of Fera < Buph < Ligs < Sdan < SenH < SenI < SenA < Vani. They were predicted to have over 70% absorption in human. However, ConFer, Rili and LevA were estimated to have poor human oral absorption. / Ko Nga Ling. / "September 2005." / Adviser: Ge Lin. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1577. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 215-239). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

In a mouse model of pulmonary thromboembolism induced by a collagen-adrenaline mixture, the SFE extract and ligustilide reduced the paralysis-death ratio, and the anti-thrombotic response of senkyunolide A was more pronounced. The effect of BDPH was not significant. Neither the SFE extract nor the three phthalides prolonged bleeding time in tail-transected mice. / In a rat myocardial ischemia-reperfusion model involving coronary artery ligation, 7-day pre-treatment with the SFE extract and ligustilide reduced ventricular arrhythmias in isolated hearts. BDPH and senkyunolide A were without significant effects. / In rat platelet-rich plasma, platelet aggregation induced by collagen and U46619 but not by adenosine diphosphate was inhibited by the SFE extract. Ligustilide inhibited the responses of all three agonists, while BDPH and senkyunolide A inhibited the collagen response only. / Raw Rhizoma Chuanxiong herb and its crude extract as obtained by supercritical fluid extraction (SFE) comprised mainly phthalides. The SFE extract and three representative phthalides, butylidenephthalide (BDPH), ligustilide and senkyunolide A, were studied on vasorelaxation, myocardial ischemia, platelet aggregation and thrombosis. The mechanisms underlying BDPH-mediated vasorelaxation were also explored. / Rhizoma Chuanxiong, the dried rhizome of Ligusticum chuanxiong Hort., is a common traditional Chinese medicine used for the treatment of cardiovascular diseases. Surprisingly, the scientific basis of its action is poorly understood. The current study aims to establish the pharmacological basis of the cardiovascular effects of Rhizoma Chuanxiong and its active constituents by examining their effects in several cardiovascular domains. / The current study demonstrated various cardiovascular actions of Rhizoma Chuanxiong, and thereby established the pharmacological basis of the effects of the herb. Phthalides, in particular BDPH, ligustilide and senkyunolide A, were important contributors to such actions. Future investigation of the SFE extract and/or individual phthalides related to the progression from in vitro and in vivo effectiveness to clinical efficacy is much anticipated. / The SFE extract, BDPH, ligustilide and senkyunolide A produced vasorelaxation on isolated preparations of rat aorta, rat saphenous vein and pig coronary artery. BDPH-mediated relaxation appeared to involve both extracellular Ca 2+-dependent (L-type voltage-operated, receptor-operated and store-operated Ca2+ channels) and independent (NO modulation, Ca2+ release from internal stores and Ca2+ desensitization) mechanisms. BDPH was also observed to augment relaxation induced by sodium nitroprusside and forskolin through mechanisms that remain undefined. / Chan Sun Kin Sunny. / "July 2005." / Advisers: G. Lin; R. L. Jones. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1575. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 190-209). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Aim. Baicalein is a bioactive flavonoid component isolated from the root of Scutellaria baicalensis, which has been used as a traditional Chinese medicinal herb for the treatment of inflammation for centuries. Although various pharmacological effects of baicalein have been demonstrated, only limited studies in rats reported pharmacokinetic of baicalein, which exhibited a low oral bioavailability due to extensive first-pass metabolism. In addition, no investigation on human oral absorption or metabolic kinetic profile was reported previously. The current project conducted a series of mechanistic studies aiming to elucidate the intestinal absorption, metabolism and disposition of baicalein. Since glucuronidation plays an important role in the first-pass metabolism of flavonoids including baicalein, additional studies on the relationship between human intestinal glucuronidation activities and chemical structures of flavonoids have also been performed. / Conclusion. Baicalein is well absorbed at intestine but subjected to extensive intestinal glucuronidation resulting in low oral bioavailability. The glucuronidation of baicalein is catalyzed by multiple UGT isozymes. The disposition of baicalein 7-O-glucuronide, the major metabolite of baicalein in vivo, is mediated by the MRP and OATP transporters. The nucleophilicity and stereo-conformation of -OH substituents are crucial for the intestinal glucuronidation of flavonoids. / Methods. For investigation on intestinal absorption, metabolism and disposition of baicalein, human Caco-2 cell monolayer model, rat in situ intestinal perfusion model, and in vitro metabolism model were employed in the present study. For the further investigation on the position preference on glucuronidation of flavonoids at human intestine, the in vitro rates of glucuronidation among seven commercially available mono-hydroxyflavones, namely 3-, 5-, 6-, 7-, 2'-, 3'- and 4'-mono-hydroxyflavones were determined and compared. / Results. The satisfactory permeabilities of baicalein obtained from both Caco-2 cell model and rat intestinal perfusion model indicated its potential good absorption at gastrointestinal tract. Therefore, absorption should not be the rate-limiting factor causing the low oral bioavailability of baicalein. However, extensive glucuronidation occurred in the rat intestine perfusion model with over 90% of baicalein being metabolized after intestinal absorption. Consistent findings were also observed in the in vitro enzyme kinetic studies of baicalein. The biotransformation of baicalein to baicalein 7-O-glucuronide was extensive in human liver microsome, human jejunum microsome, rat liver microsome, and rat jejunum microsome with intrinsic clearances (Vmax/Km) of 618, 446, 436, 298 mul/min/mg, respectively, which are orders of magnitude greater than those of most of western drugs that share the same metabolic pathway. Further enzyme kinetic studies using human recombinant glucuronosyltransferases (UGT) isozymes showed that UGT 1A1, 1A3, 1A8, 1A9, 1A7 and 2B15 were involved in the glucuronidation of baicalein with different kinetic profiles. Mechanistic studies on the disposition of baicalein 7-O-glucuronide formed from a rapid glucuronidation of baicalein in intestine demonstrated that this intracellularly formed glucuronide of baicalein could be actively extruded to both the apical and basolateral sides (the so called efflux) in Caco-2 cell model as well as rat intestinal perfusion model. It was also found that the efflux of the baicalein 7-O-glucuronide followed saturable enzyme kinetics and was effectively inhibited by multi-drug resistance associated proteins (MRP) and organic anion transporters (OATP) inhibitors. Further study on the relationship between flavonoid structures and glucuronidation activities using seven monohydroxyflavones demonstrated that the conjugation rates of 6- and 3'-monohydroxyflavones (HF) were much greater than those of 3-, 4'-, 7-, 2'-HF, while 5HF was the lowest. / Zhang Li. / "August 2006." / Advisers: Zhong Joan Zuo; Ge Lin. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1587. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 186-223). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Aim. The aim of this study was to synthesize and characterize novel analogues of [DACH-Pt-DMC] by using different stereoisomers of DACH; and to investigate any differences in in vitro activity of these complexes in human hepatocellular carcinoma (HCC), colorectal carcinoma (CRC) cell lines and acquired cisplatin or oxaliplatin resistant sub-lines, and to compare that of oxaliplatin and other established Pt-based anticancer agents. Mechanistic roles of DACH-Pt- and DMC components of the TCM-Pt complexes on affecting HCT 116 human CRC cell line were investigated by flow cytometry, COMET assay and cDNA microarray analysis. / Background. Demethylcantharidin (DMC), a modified component of the traditional Chinese medicine (TCM), integrated with a platinum (Pt) moiety created a series of TCM-Pt complexes [Pt(C8H8O 5)(NH2R)2] 1-5 which demonstrated superior antitumor activity and circumvention of cisplatin resistance in vitro. Compound 5, derived from the 1,2-diaminocyclohexane (DACH) ligand (where R=trans-C6H10) had the most potent antitumor activity and closest structural resemblance to oxaliplatin (R,R-DACH-Pt complex) which is the first Pt-based anticancer drug to demonstrate convincing clinical activity against colorectal cancer and has a mechanism of action and resistance that is clearly different from that of cisplatin and carboplatin. / Conclusion. This study is the first to examine the mechanism of anticancer activity of new complexes that integrate DMC with different isomers of DACH. It has shown that both DACH-Pt- and DMC components contribute significantly to the compounds' potent anticancer activity, but likely with different mechanisms of action. The DACH-Pt- component appears to dictate the cell cycle distribution, whereas the DMC component appears to enhance cytotoxicity by inducing more DNA damage in HCT 116 colorectal cancer cells. / Methods. DMC was reacted with appropriate DACH-Pt-(NO3) 2 intermediates, which were prepared from treatment of K2PtCl 4 with stereoisomeric DACH (RR-, SS- & cis-), followed by reaction with silver nitrate. Proton NMR, high-resolution MS, polarimetry and circular dichroism (CD) spectroscopy were used to characterize their chemical structures and optical activities. In vitro antitumor activity (IC50 of 72hr drug exposure time) were assessed by a standard MTT assay. Cell cycle analysis by flow cytometry was determined at 0, 6, 12, 18, 24, 48 and 72 h after drug treatment (cisplatin, carboplatin, oxaliplatin, DMC, compound 1 or trans-DACH-Pt-DMC analogues) at IC50 and 5 x IC50 concentrations with three to four replicates. Comet assay was performed with a fluorescent microscope and used to examine DNA damage after drug treatments (50muM of cisplatin, carboplatin, oxaliplatin, DMC, compound 1 or R,R-DACH-Pt-DMC) for 3hr. cDNA microarray was performed on Affymetrix Human Genome U133A Set and used to analyze gene expression profiles in HCT 116 exposed to trans-(+/-)-DACH-Pt-DMC or oxaliplatin at their IC50 for 72hr. / Results. The in vitro results showed that the trans-analogues were consistently the most potent amongst all the compounds tested in both HCC and CRC cell lines: the trans-(+)(1R,2R)-DACH-Pt-DMC complex, in particular, was the most effective stereoisomer. All of the stereoisomeric DACH-Pt-DMC complexes and oxaliplatin were apparently able to circumvent cisplatin resistance in Huh-7 and SK-Hep1 sub-lines, but cross resistant with oxaliplatin in HCT 116 oxaliplatin resistant sub-line. Flow cytometric analysis revealed the novel trans-DACH-Pt-DMC analogues and oxaliplatin behaved similarly: that is, the compounds at 5 x IC50 concentrations all caused a significant decrease in the S-phase population within 18h and at the same time induced G2/M arrest, and without obvious sub-G 1 phase accumulation, but distinct from that of cisplatin, carboplatin or DMC. Comet assay showed that trans-(+)-(1R,2 R)-DACH-Pt-DMC caused the most significant DNA damage at an equivalent molar concentration. Microarray analysis suggested that the mechanistic role of the DMC ligand can induce the cell cycle to accelerate from the G 1 to S-phase and cause M-phase arrest. / Yu Chun Wing. / "July 2006." / Advisers: Yee-ping Ho; Chik Fun Steve Au-Yeung. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1586. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 191-232). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.