Exploring the regulation and function of human Lats1 and Aurora A kinases in mitosis

Mitosis is the process by which sister chromatids are equally segregated into two daughter cells. Tight control in various events during mitotic progression is essential for maintaining chromosome stability. Mitotic kinases including Cyclin dependent kinase 1 (Cdk1) and Aurora family are required for regulating proper mitotic progression by phosphorylating mitotic substrates thereby, controlling their activities, localization or abundance. On the other hand, these mitotic kinases are modulated by de-novo synthesis, activators, phosphorylation and ubiquitin-dependent proteolysis. A thorough understanding of the function and regulation of mitotic kinases could further our knowledge on mitotic progression. In the first part of the thesis, we investigated the expression, localization and regulation of human Lats1 kinase, which is a close homologue of the yeast Dbf2 kinase family involved in the mitotic exit network (MEN). Despite the fact that Lats1 has been suggested to be a spindle protein that binds and inactivates Cdk1, we found that Lats1 is mainly cytoplasmic throughout the cell cycle by immunofluorescence microscopy. Both yeast two-hybrid and coimmunoprecipitation showed no significant interaction between Lats1 and Cdk1. Although Lats1 was highly phosphorylated during mitosis, no detectable kinase activity was observed. However, we identified Ste20 like kinase MST2 as the upstream regulator of human Lats1. Phosphorylation of Lats1 by Mst2 resulted in the activation of Lats1 kinase activity both in vivo and in vitro. This kinase-substrate relation was proven to be specific, as another distant Mst2 homolog, Mst4, did not possess this ability. Subsequent mass-spectrometry-based phosphosites analysis revealed that Mst2 phosphorylates Lats1 on more than five residues. Alanine mutations on Lats1T1079 and S909 impaired Lats1 kinase activity. Thus, we could not confirm the suggested role of Lat1 in mitosis. Instead, we show that similar to its Drosophila ortholog, Lats1 is involved in the Mst2 signaling pathway and might control developmentally regulated cell proliferation and apoptosis in mammals. In the second part of this thesis, we characterized hBora, a novel Aurora A interactor originally found in Drosophila. We show that hBora is upregulated and phosphorylated during mitosis. siRNA-mediated knockdown of hBora led to spindle formation defects and aneuploidy. hBora overexpression caused monoastral spindle formation and mislocalization not only of Aurora A but also Plk1. Further investigations showed that Cdk1 phosphorylation on hBoraSer252 leads to Plk1 binding and this may promote the SCF-mediated proteolysis of hBora. Indeed, Plk1 depletion led to an increase in hBora levels. Interestingly, the co-depletion of both hBora and Plk1 (to lower hBora levels in Plk1 depleted cells) rescued the localization of Aurora A to the centrosomes and bipolar spindle formation. Thus, we propose that hBora is a functional link between Plk1 and Aurora A and that by modulating the proteolysis of hBora, Plk1 could regulate Aurora A localization and activity. At the end, we also investigated the function of Aurora A and could show that Aurora A is required for centriole cohesion and centrosome separation

An analysis for more equitable revenue and expenditure allocations within Lingnan College

From the triennial 1995-98, the funds allocated from University Grants Committee to universities have decreased. In order to use the limited resources effectively, and to manage their revenue and costs efficiently, universities have to set up a better budgeting system. Therefore, the eight universities in Hong Kong are proposing the Revenue Center Management (RCM) instead of the current budgeting system. The purposes of this project focuses on the analyses of the current budgeting system adopted at Lingnan College, and the proposed RCM budgeting system

REIMPORTATION OF U.S. PHARMACEUTICALS: POLITICAL, ECONOMIC, AND LEGAL PERSPECTIVES

The high cost of prescription drugs in the United States is a problem that has engendered much political attention. One proposed solution to the prescription drug problem is to permit reimportation of U.S.-made drug products, allowing Americans to take advantage of products sold at lower prices abroad. In 2000, the United States passed such a measure known as the Medicine Equity and Drug Safety Act (“MEDSAâ€), which, if implemented, would have overturned a decade-long bad on the reimportation of pharmaceuticals without the consent of the manufacturer. Though supported by many consumer advocates and politicians, MEDSA would have had tenuous affect on drug prices and posed unnecessary risks to consumer safety. Reimportation’s theoretic results of eliminating geographic price discrimination would have detrimental results for society as a whole by reducing the incentive for drug manufacturers to innovate. Furthermore, a global pricing system for pharmaceuticals may create severe consumer losses, especially in developing counties. Lastly, reimportation of patented goods may be subject to legal challenge under current construction of the exhaustion of rights principle. Rather than considering reimportation, the government should implement a policy that provides lower-cost drugs to those who need them the most, the uninsured elderly. A policy of price discounts for uninsured elderly would improve the prescription drug situation without threatening the incentives for pharmaceutical innovation, and would lead to greater social benefits overall

Assessing the Quality of Regulatory Impact Analyses

This study provides the most comprehensive evaluation of the quality of recent economic analyses that agencies conduct before finalizing major regulations. We construct a new dataset that includes analyses of forty-eight major health, safety, and environmental regulations from mid-1996 to mid-1999. This dataset provides detailed information on a variety of issues, including an agency's treatment of benefits, costs, net benefits, discounting, and uncertainty. We use this dataset to assess the quality of recent economic analyses and to determine the extent to which they are consistent with President Clinton's Executive Order 12866 and the benefit-cost guidelines issued by the Office of Management and Budget (OMB). We find that economic analyses prepared by regulatory agencies typically do not provide enough information to make decisions that will maximize the efficiency or effectiveness of a rule. Agencies quantified net benefits for only 29 percent of the rules. Agencies failed to discuss alternatives in 27 percent of the rules and quantified costs and benefits of alternatives in only 31 percent of the rules. Our findings strongly suggest that agencies generally failed to comply with the executive order and adhere to the OMB guidelines. We offer specific suggestions for improving the quality of analysis and the transparency of the regulatory process, including writing clear executive summaries, making analyses available on the Internet, providing more careful consideration of alternatives to a regulation, and estimating net benefits of a regulation when data on costs and benefits are provided.

Assessing Regulatory Impact Analyses: The Failure of Agencies to Comply With Executive Order 12,866

None.Environment, Health and Safety, Regulatory Reform

Using Internet‐Based Vignette Methods to Understand Elder Residential Choices

This paper illustrates an innovative method of administering fractional factorial surveys (vignettes) using the internet. The approach makes it possible to use video clips to deliver information. The method also provides subjects with interactive options before making judgments. A study to determine the views of older people regarding residential options is used to illustrate the method. The study found that the following characteristics of vignette persons affected subject recommendations: personal introduction, functional status, social network, and current housing characteristics. However, characteristics of retirement community features and personal financial status did not affect recommendations

The relationship of asthma and the pattern of adiposity in adult Chinese

Poster presentationpublished_or_final_versionThe 15th Medical Research Conference, Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 56, abstract no. 9

PLASER: Pronunciation Learning via Automatic Speech Recognition

PLASER is a multimedia tool with instant feedback designed to teach English pronunciation for high-school students of Hong Kong whose mother tongue is Cantonese Chinese. The objective is to teach correct pronunciation and not to assess a student's overall pronunciation quality. Major challenges related to speech recognition technology include: allowance for non-native accent, reliable and corrective feedbacks, and visualization of errors

Using the internet to administer more realistic vignette experiments

This article illustrates an innovative method of administering stated choice studies (or vignette experiments) using computers and the Internet. The use of video clips to deliver information to research participants makes vignettes more realistic, helps to engage interest of research participants, and can reduce framing effects. The method also provides research participants with interactive options before making judgments. A study to determine the views of older people regarding residential options is used to illustrate the method. Even older people with limited experience in using computers participated successfully. The study findings showed that research participants responded both to the audiovisual characteristics of vignette persons and to the variables in the vignette structure

Knee stability assessment on anterior cruciate ligament injury: clinical and biomechanical approaches

Anterior cruciate ligament (ACL) injury is common in knee joint accounting for 40% of sports injury. ACL injury leads to knee instability, therefore, understanding knee stability assessments would be useful for diagnosis of ACL injury, comparison between operation treatments and establishing return-to-sport standard. This article firstly introduces a management model for ACL injury and the contribution of knee stability assessment to the corresponding stages of the model. Secondly, standard clinical examination, intra-operative stability measurement and motion analysis for functional assessment are reviewed. Orthopaedic surgeons and scientists with related background are encouraged to understand knee biomechanics and stability assessment for ACL injury patients