Joyce Ching - Academia.edu (original) (raw)

Papers by Joyce Ching

The hook-basal body (HBB) is a key intermediate structure in the flagellar assembly pathway in Sa... more The hook-basal body (HBB) is a key intermediate structure in the flagellar assembly pathway in Salmonella typhimurium. The FlgM protein inhibits the flagellum-specific transcription factor 28 in the absence of the intact HBB structure and is secreted out of the cell following HBB completion. The flk gene encodes a positive regulator of the activity of FlgM at an assembly step just prior to HBB completion: at the point of assembly of the P-and L-rings. FlgM inhibition of 28 -dependent class 3 flagellar gene transcription was relieved in Pand L-ring assembly mutants (flgA, flgH, and flgI) by introduction of a null mutation in the flk gene (J. E. Karlinsey et al., J. Bacteriol. 179:2389-2400, 1997). In P-and L-ring mutant strains, recessive mutations in flk resulted in a reduction in intracellular FlgM levels to those seen in wild-type (Fla ؉ ) strains. The reduction in intracellular FlgM levels by mutations in the flk gene was concomitant with a 10-fold increase in transcription of the flgMN operon compared to that of the isogenic flk ؉ strain, while transcription of the flgAMN operon was unaffected. This was true for both direct measurement of the flgAMN and flgMN mRNA transcripts by RNase T2 protection assays and for lac operon fusions to either the flgAMN or flgMN promoter. Loss of Flk did not allow secretion of FlgM through basal-body structures lacking the P-and L-rings. Intracellular FlgM was stable to proteolysis, and turnover occured primarily after export out of the cell. Loss of Flk did not result in increased FlgM turnover in either P-or L-ring mutant strains. With lacZ translational fusions to flgM, a null mutation in flk resulted in a significant reduction of flgM-lacZ mRNA translation, expressed from the class 3 flgMN promoter, in P-and L-ring mutant strains. No reduction in either flgAMN or flgMN mRNA stability was measured in the absence of Flk in Fla ؉ , ring mutant, or HBB deletion strains. We conclude that the reduction in the intracellular FlgM levels by mutation in the flk gene is only at the level of flgM mRNA translation.

Analysis of the Cargo Service Dynamics in East Asian Airports

International Journal of Applied Logistics, 2010

Page 1. International Journal of Applied Logistics, 1(2), 1-22, April-June 2010 1 Copyright © 201... more Page 1. International Journal of Applied Logistics, 1(2), 1-22, April-June 2010 1 Copyright © 2010, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Keywords ...

Bioorganic & Medicinal Chemistry Letters, 1993

Synthesis and antiplatelet activity of a series of structurally simple thromboxane A2 receptor an... more Synthesis and antiplatelet activity of a series of structurally simple thromboxane A2 receptor antagonists are described The cir-cyclopentane analog (-)-lc was the most potent compound in this series with 1~0 and &values of 15 nM and 4.3ti.O nM, respectively. In radioligand binding assay, nanr-cyclopentane analog (-)-ld was the most potent ligand with a Ktt value of 0.5fo.3 nM.

Transportation Research Part E-logistics and Transportation Review, 2009

Data envelopment analysis Factor productivity and price Outsourcing Country-specific effect a b s... more Data envelopment analysis Factor productivity and price Outsourcing Country-specific effect a b s t r a c t This paper analyses various dimensions of operational efficiencies in major Asia Pacific airports through Data Envelopment Analysis (DEA) models that simultaneously account for external macroeconomics and price factors. Results from this study show that technical, scale and mix efficiencies are high among the major Asia Pacific airports. In addition, significant disparities in cost efficiencies were detected amongst these airports. These disparities can be attributed to the presence of country-specific effect and differences in allocative efficiencies. A virtual airport is then introduced as a superior performer to rank the efficiency performances of airports.

Nucleic Acids Research, 2005

We have previously characterized transcription factor LZIP to be a growth suppressor targeted by ... more We have previously characterized transcription factor LZIP to be a growth suppressor targeted by hepatitis C virus oncoprotein. In search of proteins closely related to LZIP, we have identified a liver-enriched transcription factor CREB-H. LZIP and CREB-H represent a new subfamily of bZIP factors. CREB-H activates transcription by binding to cAMP responsive element, box B, and ATF6-binding element. Interestingly, CREB-H has a putative transmembrane (TM) domain and it localizes ambiently to the endoplasmic reticulum. Proteolytic cleavage that removes the TM domain leads to nuclear translocation and activation of CREB-H. CREB-H activates the promoter of hepatic gluconeogenic enzyme phosphoenolpyruvate carboxykinase. This activation can be further stimulated by cAMP and protein kinase A. CREB-H transcript is exclusively abundant in adult liver. In contrast, the expression of CREB-H mRNA is aberrantly reduced in hepatoma tissues and cells. The enforced expression of CREB-H suppresses the proliferation of cultured hepatoma cells. Taken together, our findings suggest that the liver-enriched bZIP transcription factor CREB-H is a growth suppressor that plays a role in hepatic physiology and pathology.

International Journal of Production Economics, 2010

This paper introduces an air cargo supply chain operations reference (ACSCOR) model to examine th... more This paper introduces an air cargo supply chain operations reference (ACSCOR) model to examine the integrated impact of airport operating strategies and industrial forces on airport performances, and quantifies the economic benefits of the air cargo service business. In the light of Singapore and Hong Kong statistics, it is shown that the cargo traffic at an airport is significantly influenced by its operating characteristics, the performances of its downstream airfreight and supporting logistics industry, and the economic environment that it is functioning within. Through the traditional economic models, it is found that on average Hong Kong experiences a higher accelerator effect but lower multiplier effect in airport investment compared to Singapore. While the multiplier effect may signify that Singapore can benefit from higher returns in terms of the spillover effect to the overall air cargo supply chain, the higher accelerator effect in Hong Kong corresponds to the empirical results from the ACSCOR model that advocate Chek Lap Kok airport increasing its physical inputs relative to human inputs.

Factor substitution and complementarity in the Asia airport industry

Journal of Air Transport Management, 2006

... The results reveal that outsourcing has emerged from being a substitute for labor and a compl... more ... The results reveal that outsourcing has emerged from being a substitute for labor and a complementary factor to capital in the late 1990s to become a substitute for both labor and capital. ... It follows from Eqs. (2) and (3) that (4) View the MathML source. ...

New Bayesian Model Updating Algorithm Applied to a Structural Health Monitoring Benchmark

Structural Health Monitoring-an International Journal, 2004