Jeong-Uk Kim

Molecular Epidemiological Profile of Rotavirus in South Korea, July 2002 through June 2003: Emergence of G4P[6] and G9P[8] Strains

To determine the distribution of rotavirus strain genotypes in South Korea, rotavirus-positive stool specimens were collected from July 2002 through June 2003 at 8 hospitals in the Korean Rotavirus Strain Surveillance Network, and they were genotyped by means of reverse-transcription polymerase chain reaction. The globally uncommon G4P[6] type was the most prevalent type identified among strains (27% of strains), the newly emerging G9P[8] strain accounted for 11% of strains, and the globally common genotypes (i.e., G1P[8], G2P[4], G3P[8], and G4P[8]) constituted 55% of the strains characterized. Ninety percent of G4P[6] strains were detected in specimens obtained from neonates. Common genotypes were responsible for the rotavirus epidemic that began in January 2003 and ended in May 2003; however, an early peak in infections with the G4P[6] strain occurred from August through October 2002, and infections with this strain were detected throughout the remaining study period. G4P[6] strains were most commonly identified at 6 urban health care centers, but they were absent from 2 rural health care centers. The newly emerging strain G9P[8] represented a relatively greater proportion of strains identified at a hospital in the central region of Korea and at 2 hospitals in the southern region. The identification of novel rotavirus genotypes in this laboratory-based surveillance study underscores the importance to public health of continued strain surveillance among children for whom prevention of rotavirus infection by vaccination might be considered.

Carvedilol Reduces Plasma 8-Hydroxy-2′-Deoxyguanosine in Mild to Moderate Hypertension A Pilot Study

The purpose of this pilot study was to test whether carvedilol has a protective effect against oxidative deoxyribonucleic acid (DNA) damage in human hypertension in vivo. Carvedilol’s antioxidant effect has mostly focused on lipid or amino acid so far. However, there has been no data that carvedilol reduces DNA damage in human hypertension. Never-treated mild to moderate hypertension patients and age- and sex-matched control subjects volunteered for the study. The hypertension subjects were given 12.5 or 25 mg of carvedilol or hydrochlorothiazide orally for 2 months and controls were not given any. Fasting blood samples were collected before and after carvedilol. Plasma highly sensitive 8-hydroxy-2′-deoxyguanosine (hs8-OHdG) and high-sensitivity C-reactive protein (hsCRP) were checked with the samples. There were no statistical differences in clinical characteristics in 3 groups. The hs8-OHdG declined from 9.07±4.23 ng/mL to 5.74±3.89 ng/mL (P=0.002) after carvedilol. However, it did not show significant reduction after hydrochlorothiazide (9.01±3.89 versus 8.23±4.12 ng/mL; P=NS). In the control group, the hs8-OHdG concentration was 3.41±2.03 ng/mL and 3.01±2.65 ng/mL at baseline and 2 months later, respectively (P=NS). The baseline hs8-OHdG levels were higher in hypertension groups compared with control (P=0.000). The hsCRP had no significant difference before and after the tested drugs in 2 hypertension groups (group A: 0.21±0.51 versus 0.19±0.37 mg/dL; group B: 0.20±0.45 versus 0.18±0.42 mg/dL). In conclusion, DNA damage caused by reactive oxygen species occurs more in the hypertension patients than normals. Carvedilol significantly reduces DNA damage in the hypertension patients.

Multiplex Real-Time PCR Assay and Melting Curve Analysis for Identifying Mycobacterium tuberculosis Complex and Nontuberculous Mycobacteria

ABSTRACT A multiplex real-time PCR assay and melting curve analysis for identifying 23 mycobacterial species was developed and evaluated using 77 reference strains and 369 clinical isolates. Concordant results were obtained for all 189 (100%) isolates of the Mycobacterium tuberculosis complex and 169 (93.9%) isolates of nontuberculous mycobacteria. Our results showed that this multiplex real-time PCR assay is an effective tool for the mycobacterial identification from cultures.

Rho-Associated Kinase 2 Polymorphism in Patients With Vasospastic Angina

Background and Objectives Recent studies indicate that in response to vasoconstrictor stimuli, the small GTPase RhoA and its down-stream effector, Rho-associated kinase 2 (ROCK)/Rho-kinase, are associated with hypercontraction of the vascular smooth muscle of coronary arteries through augmentation of myosin light chain phosphorylation and Ca2+ sensitization. Expression of ROCK/Rho-kinase mRNA was significantly increased and up-regulated in the spastic coronary artery in a porcine model, and a specific inhibitor of ROCK/Rho-kinase inhibited coronary artery spasm in humans. We therefore explored the role of ROCK2 polymorphisms in the pathogenesis of vasospastic angina (VA). Subjects and Methods We studied 106 patients with VA who exhibited spontaneous or provoked coronary spasm during coronary angiography and compared the prevalence of ROCK2 polymorphisms between this group of patients with VA and controls whose angiograms were normal, and in whom the ergonovine test did not cause spasm (n=107). Five single nucleotide polymorphisms (SNPs) of the ROCK2 gene were selected. SNPs were genotyped by high-resolution melting. Linkage disequilibrium and haplotype analyses were performed using the SHEsis program. Results The prevalence of genotypes of the 5 interesting SNPs in patients with VA was not different from that in the control group. In haplotype analysis, the haplotype G-T-C-T-G (in order of rs978906, rs2271621, rs2230774, rs1515210, and rs3771106) was significantly associated with a decreased risk of VA (p=0.007). Conclusion The haplotype G-T-C-T-G in the ROCK2 gene had a protective effect against VA, suggesting the involvement of ROCK2 in VA pathogenesis.

Multiplex Real-Time PCR Assay for Detection of Methicillin-Resistant Staphylococcus aureus (MRSA) Strains Suitable in Regions of High MRSA Endemicity

ABSTRACT A multiplex real-time PCR assay that simultaneously detects the mecA, staphylococcal cassette chromosome (SCCmec)-open reading frame X (orfX) junction, and staphylococcal 16S rRNA genes was developed and evaluated using 444 staphylococcal strains. We demonstrated that this assay resulted in fewer false-positive results than a single-locus real-time PCR assay that amplified the SCCmec-orfX junction. This assay would be useful in a clinical laboratory in a region of high endemicity for methicillin-resistant Staphylococcus aureus (MRSA) infections.

Vitamin D receptor polymorphisms and Parkinson's disease in a Korean population: Revisited.

Recently, the effect of genetic variants in the Vitamin D receptor (VDR) gene on Parkinsons disease (PD) has gained interest. However, the precise relationship between VDR polymorphisms and PD remains unclear. In Korea, one study reported an association between VDR gene polymorphisms and PD. However, this study was conducted with a small sample size, and only the Bsml locus was evaluated. Therefore, further investigations about the relationship between VDR polymorphisms and PD are necessary in a Korean population. A total of 300 subjects were included in this study. One hundred and forty-six PD patients were diagnosed according to the United Kingdom Parkinsons Disease Society Brain Bank (UKPDBB) criteria with abnormal dopamine transporter imaging, and 154 healthy control subjects were also enrolled. We used a TaqMan genotyping assay to identify four SNPs of the VDR gene, including BsmI, FokI, ApaI, and TaqI (rs731236, rs2228570, rs7976091, and rs731236). A significant association was not noted between the risk of PD and genetic polymorphisms in the four loci in a Korean population. However, when the genetic variants of the VDR gene were analyzed after adjusting for the serum 25-OH vitamin D3 level, the TaqI and BsmI minor allele increased the risk of PD. Our data suggest no correlation between PD and the VDR polymorphisms, including BsmI, FokI, ApaI, and TaqI, in a Korean population; however, the results should be interpreted carefully because gene-environment interactions may exist. Further investigations of the VDR and its relationship with PD are required to identify the role of vitamin D in the pathogenesis of PD.

Direct identification of mycobacteria from culture media using a multiplex real-time PCR assay: report on its application in a clinical laboratory in a region of high tuberculosis endemicity

There are few commercial assays that easily and correctly identify the mycobacteria from culture in a clinical laboratory with a high workload. Thus, we developed and evaluated a scheme for the identification of mycobacteria using a multiplex real-time PCR assay and report on its application in our laboratory. The scheme consisted of 3 stepwise PCRs. Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) were differentially detected in the step 1 PCR, and the NTM species were identified in the step 2 and 3 PCRs. Over the 1.5-year study period, 1136 isolates of MTC and 618 isolates of NTM were detected, and the species of 608 (98.4%) of the 618 NTM isolates were identified. We conclude that the established scheme is a very useful diagnostic approach for the rapid and accurate identification of MTC and clinically relevant NTM in a clinical laboratory in a region where tuberculosis is endemic.

Association of endothelin-1 gene polymorphisms with variant angina in Korean patients.

Abstract Background: The incidence of variant angina in oriental patients is higher than in patients from the Western world. Endothelin-1 (ET-1) seems to be associated with coronary vasospasm in variant angina, suggesting that ET-1 gene variants may be important in coronary vasospasm in variant angina. We wanted to assess potential association between Korean variant angina and three polymorphisms of the ET-1 gene, which include the +138delA polymorphism in exon 1, G8002A polymorphism in intron 4 and Lys198Asn polymorphism in exon 5. Method: A total of 97 patients with variant angina and 111 healthy controls were studied. Analyses of the +138delA, G8002A and Lys198Asn polymorphisms were carried out by polymerase chain reaction-restriction fragment length polymorphism and haplotype techniques. Results: The frequency of mutant 138delA allele was lower in the angina group than in controls [p=0.003, odds ratio (OR)=0.42] and the frequencies of A8002 or Asn198 were significantly higher in the variant angina group than in controls (p=0.005, OR=2.17 or p=0.009, OR=1.75, respectively). According to haplotype analysis, 4A/A8002/Asn198 haplotype was significantly associated with the disease (p=0.0162, OR=2.33) and 3A/G8002/Lys198 haplotype was protective against the disease (p=0.0043, OR=0.54). Conclusions: The ET-1 gene polymorphisms, such as +138delA, G8002A and Lys198Asn polymorphisms, seem to be associated with variant angina in Korean patients. Clin Chem Lab Med 2008;46:1575–80.

Direct identification of mycobacteria from clinical specimens by multiplex real-time PCR.

To directly identify clinically relevant mycobacteria from clinical specimens, we have developed a multiplex real‐time PCR assay with hydrolysis probes that can identify 20 mycobacterial species.

Paradigm for diagnosing mycobacterial disease: direct detection and differentiation of Mycobacterium tuberculosis complex and non-tuberculous mycobacteria in clinical specimens using multiplex real-time PCR

Aims Mycobacterium tuberculosis and non-tuberculous mycobacteria (NTM) are clinically different, and the rapid detection and differentiation of M. tuberculosis complex (MTBC) and NTM is crucial for patient management and infection control. Given the slow growth of most pathogenic mycobacteria, nucleic acid amplification assays are excellent tools for direct identification of mycobacteria in clinical specimens. Recently, a multiplex real-time PCR assay was developed that can directly detect 20 mycobacterial species in clinical specimens. Here, we evaluated the diagnostic performance of the assay for diagnosing mycobacterial disease under routine laboratory conditions. Methods A total of 3334 specimens collected from 1437 patients suspected of tuberculosis infection were subjected to acid-fast bacilli staining, conventional culture and the multiplex real-time PCR assay. To evaluate the sensitivity and specificity of the assay, the overall diagnosis of tuberculosis was defined by positive culture plus medical history, and the 2007 American Thoracic Society and Infectious Disease Society of America diagnostic criteria for NTM disease were applied. Results The sensitivity, specificity, positive predictive value and negative predictive value were 87.5%, 99.6%, 96.1% and 98.5%, respectively, for the detection of MTBC isolates and 53.3%, 99.9%, 95.2%, and 98.9%, respectively, for detecting NTM isolates. Conclusions Thus, the assay can correctly differentiate between MTBC and NTM isolates in clinical specimens and would be a useful tool for the rapid differentiation of tuberculosis and NTM disease, despite its limited sensitivity for the diagnosis of NTM disease.