Seok Hwee Koo

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This study evaluated the utility of oral sulfasalazine as a probe substrate for Breast Cancer Resistance Protein (BCRP; ABCG2) activity by assessing the impact of genetic variation or coadministration of an inhibitor (pantoprazole) on plasma and urine pharmacokinetics of sulfasalazine and metabolites. Thirty-six healthy male subjects prescreened for ABCG2(More)
AIMS To determine the genetic variability of long QT syndrome (LQTS)-associated genes (KCNQ1, HERG, KCNE1 and KCNE2) among three distinct ethnic groups in the Singapore population. METHODS Genomic DNA samples from up to 265 normal healthy Chinese, 118 Malay and 139 Indian volunteer subjects were screened for genetic variations in the coding region of the(More)
MRP2 is a drug transporter that is responsible for the gastrointestinal absorption and biliary excretion of a wide variety of endogenous and xenobiotic compounds, including many clinically used drugs. This study aims to identify genetic variations of ABCC2 gene in three distinct ethnic groups of the Singaporean population (n = 288). The coding region of the(More)
We analyzed the coding regions of the cardiac calcium-handling genes, ryanodine receptor 2 (RyR2) and calsequestrin 2 (CASQ2) for genetic variants in a healthy Chinese population (n=95) and in a cohort of 28 sudden unexplained death victims. Mutations in RyR2 and CASQ2 have been shown to alter calcium homeostasis during excitation-contraction coupling and(More)
The novel organic cation transporter 1 (OCTN1) is a multispecific, bidirectional and pH-dependent organic cation transporter with low carnitine transport activity. It is a transporter of the physiological substance ergothioneine and mediates the transport of a variety of organic cations such as tetraethylammonium, pyrilamine and quinidine. This study(More)
AIMS A number of drugs are substrates or inhibitors of the efflux transporter breast cancer resistance protein (BCRP; ABCG2), which can limit systemic exposure by reducing absorption and/or increasing biliary elimination. The identification of a BCRP-selective clinical probe drug would provide a useful tool to understand the effect of genetic polymorphisms(More)
1. Pharmacogenetics refers to the study of genetically controlled variations in drug response. Functional variants caused by single nucleotide polymorphisms (SNPs) in genes encoding drug-metabolising enzymes, transporters, ion channels and drug receptors have been known to be associated with interindividual and interethnic variation in drug response.(More)
The human concentrative nucleoside transporter (hCNT2), also known as SLC28A2, plays an important role in the cellular uptake across intestinal membrane of some naturally occurring nucleosides and nucleoside analogs. This study aims to determine the genetic variability of hCNT2 (SLC28A2) in three major Asian ethnic groups residing in Singapore: Chinese,(More)
Novel organic cation transporter 2 (OCTN2) is a multispecific, bidirectional, pH-dependent organic cation transporter. It can function as a carnitine co-transporter with higher affinity for carnitine than OCTN1 but also functions as a uniporter for other cations. Drugs such as verapamil, pyrilamine and beta-lactam antibiotics have been characterized as(More)
OATP1B1 is a liver-specific transporter that mediates the uptake of various endogenous and exogenous compounds including many clinically used drugs from blood into hepatocytes. This study aims to identify genetic variations of SLCO1B1 gene in three distinct ethnic groups of the Singaporean population (n=288). The coding region of the gene encoding the(More)