Publications by authors named "Wai Ling Chan"

A series of 5-aryl-2-amino-midazohiaiazole (ITD) derivatives were identified by a phenotype-based high-throughput screening using a blood stage () growth inhibition assay. A lead optimization program focused on improving antiplasmodium potency, selectivity against human kinases, and absorption, distribution, metabolism, excretion, and toxicity properties and extended pharmacological profiles culminated in the identification of (), which demonstrates potent cellular activity against 3D7 (EC = 0.006 μM) and achieves "artemisinin-like" kill kinetics with a parasite clearance time of <24 h.

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Dengue virus (DENV) is a mosquito-borne flavivirus that poses a threat to public health, yet no antiviral drug is available. We performed a high-throughput phenotypic screen using the Novartis compound library and identified candidate chemical inhibitors of DENV. This chemical series was optimized to improve properties such as anti-DENV potency and solubility.

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Monophosphate prodrug analogs of 2'-deoxy-2'-fluoro-2'--methylguanosine have been reported as potent inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase. These prodrugs also display potent anti-dengue virus activities in cellular assays although their prodrug moieties were designed to produce high levels of triphosphate in the liver. Since peripheral blood mononuclear cells (PBMCs) are among the major targets of dengue virus, different prodrug moieties were designed to effectively deliver 2'-deoxy-2'-fluoro-2'--methylguanosine monophosphate prodrugs and their corresponding triphosphates into PBMCs after oral administration.

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The four serotypes of dengue virus (DENV-1 to -4) represent the most prevalent mosquito-borne viral pathogens in humans. No clinically approved vaccine or antiviral is currently available for DENV. Here we report a spiropyrazolopyridone compound that potently inhibits DENV both in vitro and in vivo.

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Spiropyrazolopyridone 1 was identified, as a novel dengue virus (DENV) inhibitor, from a DENV serotype 2 (DENV-2) high-throughput phenotypic screen. As a general trend within this chemical class, chiral resolution of the racemate revealed that R enantiomer was significantly more potent than the S. Cell-based lead optimization of the spiropyrazolopyridones focusing on improving the physicochemical properties is described.

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Tetrahydropyrazolo[1,5-a]pyrimidine scaffold was identified as a hit series from a Mycobacterium tuberculosis (Mtb) whole cell high through-put screening (HTS) campaign. A series of derivatives of this class were synthesized to evaluate their structure-activity relationship (SAR) and structure-property relationship (SPR). Compound 9 had a promising in vivo DMPK profile in mouse and exhibited potent in vivo activity in a mouse efficacy model, achieving a reduction of 3.

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Objectives: The purpose of this study was to examine the angiographic and clinical results of stent full metal jacket in treating long lesions using everolimus-eluting stents (EES).

Background: Data are lacking regarding the use of EES for this lesion subgroup.

Methods: From 2007 to 2011, 77 symptomatic patients who had severe coronary stenoses necessitating implantation of stents with total length longer than 60 mm were treated with overlapping EES.

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Unlabelled: INTRODUCTION (PURPOSE OF THE STUDY): The objective of this study was to assess whether dual-time-point (18)F-fluoro-2-deoxyglucose ((18)F-FDG)-PET/CT imaging improved the evaluation of suspected malignancy and if there was any resulting change in management.

Methods: A total of 53 patients with suspected malignancy were investigated by performing two static acquisitions started at mean times t = 64 and t = 155 min after the tracer injection. The total number of malignant lesions was 133 and the total number of benign lesions was 61.

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Crystal structure analysis of Flavivirus methyltransferases uncovered a flavivirus-conserved cavity located next to the binding site for its cofactor, S-adenosyl-methionine (SAM). Chemical derivatization of S-adenosyl-homocysteine (SAH), the product inhibitor of the methylation reaction, with substituents that extend into the identified cavity, generated inhibitors that showed improved and selective activity against dengue virus methyltransferase (MTase), but not related human enzymes. Crystal structure of dengue virus MTase with a bound SAH derivative revealed that its N6-substituent bound in this cavity and induced conformation changes in residues lining the pocket.

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We recently reported that (2R,3R,4R,5R)-2-(4-amino-pyrrolo[2,3-d]pyrimidin-7-yl)-3-ethynyl-5-hydroxy-methyl-tetrahydro-furan-3,4-diol is a potent inhibitor of dengue virus (DENV), with 50% effective concentration (EC(50)) and cytotoxic concentration (CC(50)) values of 0.7 microM and >100 microM, respectively. Here we describe the synthesis, structure-activity relationship, and antiviral characterization of the inhibitor.

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A novel class of compounds containing N-sulfonylanthranilic acid was found to specifically inhibit dengue viral polymerase. The structural requirements for inhibition and a preliminary structure-activity relationship are described. A UV cross-linking experiment was used to map the allosteric binding site of the compound on the viral polymerase.

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Dengue virus (DENV), a mosquito-borne flavivirus, is a major public health threat. The virus poses risk to 2.5 billion people worldwide and causes 50 to 100 million human infections each year.

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Bacterial peptide deformylase (PDF) belongs to a subfamily of metalloproteases catalyzing the removal of the N-terminal formyl group from newly synthesized proteins. We report the synthesis and biological activity of highly potent inhibitors of Mycobacterium tuberculosis (Mtb) PDF enzyme as well as the first X-ray crystal structure of Mtb PDF. Structure-activity relationship and crystallographic data clarified the structural requirements for high enzyme potency and cell based potency.

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A recombinant form of yellow fever virus (YFV) NS3 protease, linked via a nonapeptide to the minimal NS2B co-factor sequence (CF40-gly-NS3pro190), was expressed in Escherichia coli and shown to be catalytically active. It efficiently cleaved the fluorogenic tetrapeptide substrate Bz-norleucine-lysine-arginine-arginine-AMC, which was previously optimized for dengue virus NS2B/3 protease. A series of small peptidic inhibitors based on this substrate sequence readily inhibited its enzymic activity.

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A series of inhibitors related to the benzoyl-norleucine-lysine-arginine-arginine (Bz-nKRR) tetrapeptide aldehyde was synthesized. When evaluated against the West Nile virus (WNV) NS3 protease, the measured IC(50) ranges from approximately 1 to 200 microM. Concurrently, a modeling study using the recently published crystal structure of the West Nile NS3/NS2B protease complex (pdb code 2FP7) was conducted.

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With the aim of discovering potent and selective dengue NS3 protease inhibitors, we systematically synthesized and evaluated a series of tetrapeptide aldehydes based on lead aldehyde 1 (Bz-Nle-Lys-Arg-Arg-H, K(i)=5.8 microM). In general, we observe that interactions of P(2) side chain are more important than P(1) followed by P(3) and P(4).

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Substrate-based tetrapeptide inhibitors with various warheads were designed, synthesized, and evaluated against the Dengue virus NS3 protease. Effective inhibition was achieved by peptide inhibitors with electrophilic warheads such as aldehyde, trifluoromethyl ketone, and boronic acid. A boronic acid has the highest affinity, exhibiting a K(i) of 43 nM.

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Pulmonary embolism (PE) remains a common preventable cause of death in hospitalized patients. The purpose of this study is to examine the in-hospital management, complications of treatment and clinical outcomes of inpatients undergoing lung scintigraphy for the diagnosis of PE in a regional hospital. Two hundred consecutive inpatients with suspected PE were enrolled.

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Primary breast carcinomas are generally thallium (Tl-201) avid but uncommonly accumulate gallium (GA-67). Therefore, GA-67 scans are not routinely performed in patients with suspected breast cancer. We report a rare case of a primary breast carcinoma with bone marrow metastases where the primary lesion was GA-67 avid but did not accumulate Tl-201.

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