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1.  Prospective observation on the association of snoring with subclinical changes in carotid atherosclerosis over four years 
Sleep medicine  2014;15(7):769-775.
Although there is a growing interest in the independent effect of snoring on carotid atherosclerosis, few studies have observed the relationship between snoring and change in carotid atherosclerosis prospectively. Therefore, the present study aimed to examine prospectively the association of snoring with subclinical changes in carotid atherosclerosis during a four-year period.
Participants in an ongoing prospective cohort study (n = 3129) were enrolled. Subclinical changes in carotid atherosclerosis were assessed using: (i) mean and maximum intima-media thickness (IMT) on both common carotid arteries; (ii) prevalence of elevated IMT (maximum IMT ≥1.0 mm); and (iii) presence of plaque. Measurement was performed using B-mode ultrasonogram at baseline and after two and four years. Subjects were classified into three groups, based on self-reported snoring frequency at baseline: habitual, occasional, and non-snorer.
After adjustment for conventional cardiovascular risk factors and self-reported witnessed sleep apnea, the present study found significant cross-sectional differences in mean and maximum IMT between female snorers and non-snorers at baseline only. The changes in IMTs and presence of plaque over four years, however, did not differ by three groups, with different snoring frequency in both genders.
Snoring did not accelerate subclinical change in carotid atherosclerosis during a four-year follow-up, although baseline difference in IMT between snorers and non-snorers was significant in women, independent of witnessed sleep apnea. Additional longer-term studies with objective assessment of snoring are needed.
PMCID: PMC4127330  PMID: 24841110
Atherosclerosis; Cardiovascular disease; Carotid atherosclerosis; Prospective study; Sleep-related breathing disorders; Snoring
2.  Low Serum Concentrations of Moxifloxacin, Prothionamide, and Cycloserine on Sputum Conversion in Multi-Drug Resistant TB 
Yonsei Medical Journal  2015;56(4):961-967.
Low serum concentrations of drugs used to treat multi-drug resistant tuberculosis (MDR-TB) have occasionally been associated with treatment failure. We determined the frequencies of low serum concentrations of anti-MDR-TB drugs, and assessed the effects of these concentrations on 2-month sputum conversion.
Materials and Methods
The serum levels of moxifloxacin (MF), prothionamide (PTH), and cycloserine (CS) were determined for 89 serum samples by high-pressure liquid chromatography-tandem mass spectrometry.
Low serum concentrations of MF, PTH, and CS below the minimal levels of the normal ranges were 83.3% (20/24), 59.2% (29/49), and 71.2% (47/66), respectively. There were no significant differences between the 2-month sputum conversion group (n=25) and the 2-month sputum non-conversion group (n=4) in median drug concentrations (µg/mL) of MF (1.46 vs. 1.60), PTH (0.91 vs. 0.70), and CS (14.90 vs. 14.90). However, a poor compliance rate was significantly greater in the 2-month sputum non-conversion group (75.0%, 3/4) than in the 2-month sputum conversion group (0%, 0/25) (p=0.001).
The frequency of low serum concentrations of anti-MDR-TB drugs was substantial and might not affect the 2-month sputum conversion rate. Larger prospective studies with timely sampling are needed to investigate the role of therapeutic drug monitoring in MDR-TB.
PMCID: PMC4479863  PMID: 26069117
Tuberculosis; multidrug resistance; moxifloxacin; prothionamide; cycloserine; drug monitoring
3.  A meta-analysis of genome-wide association studies for adiponectin levels in East Asians identifies a novel locus near WDR11-FGFR2 
Human Molecular Genetics  2013;23(4):1108-1119.
Blood levels of adiponectin, an adipocyte-secreted protein correlated with metabolic and cardiovascular risks, are highly heritable. Genome-wide association (GWA) studies for adiponectin levels have identified 14 loci harboring variants associated with blood levels of adiponectin. To identify novel adiponectin-associated loci, particularly those of importance in East Asians, we conducted a meta-analysis of GWA studies for adiponectin in 7827 individuals, followed by two stages of replications in 4298 and 5954 additional individuals. We identified a novel adiponectin-associated locus on chromosome 10 near WDR11-FGFR2 (P = 3.0 × 10−14) and provided suggestive evidence for a locus on chromosome 12 near OR8S1-LALBA (P = 1.2 × 10−7). Of the adiponectin-associated loci previously described, we confirmed the association at CDH13 (P = 6.8 × 10−165), ADIPOQ (P = 1.8 × 10−22), PEPD (P = 3.6 × 10−12), CMIP (P = 2.1 × 10−10), ZNF664 (P = 2.3 × 10−7) and GPR109A (P = 7.4 × 10−6). Conditional analysis at ADIPOQ revealed a second signal with suggestive evidence of association only after conditioning on the lead SNP (Pinitial = 0.020; Pconditional = 7.0 × 10−7). We further confirmed the independence of two pairs of closely located loci (<2 Mb) on chromosome 16 at CMIP and CDH13, and on chromosome 12 at GPR109A and ZNF664. In addition, the newly identified signal near WDR11-FGFR2 exhibited evidence of association with triglycerides (P = 3.3 × 10−4), high density lipoprotein cholesterol (HDL-C, P = 4.9 × 10−4) and body mass index (BMI)-adjusted waist–hip ratio (P = 9.8 × 10−3). These findings improve our knowledge of the genetic basis of adiponectin variation, demonstrate the shared allelic architecture for adiponectin with lipids and central obesity and motivate further studies of underlying mechanisms.
PMCID: PMC3900106  PMID: 24105470
4.  Sex-specific differences in the association of a common aldehyde dehydrogenase 2 gene polymorphism and alcohol consumption with stroke risk in a Korean population: a prospective cohort study 
It is well-known that alcohol consumption is associated with stroke risk as well as with aldehyde dehydrogenase 2 gene (ALDH2) polymorphisms. However, it is unclear whether ALDH2 polymorphisms are associated with stroke risk independent of alcohol consumption and whether such association is modified by sex. We evaluated sex-specific associations of a common ALDH2 polymorphism and alcohol consumption with stroke risk in a Korean population.
We conducted a prospective cohort study involving 8,465 men and women, aged 40-69 years and free of stroke between June, 2001 and January, 2003, and followed for the development of stroke. We identified new cases of stroke, which were self-reported or ascertained from vital registration data. Based on genome-wide association data, we selected a single-nucleotide polymorphism (rs2074356), which shows high linkage disequilibrium with the functional polymorphism of ALDH2. We conducted Cox proportional hazards regression analysis considering potential risk factors collected from a baseline questionnaire.
Over the median follow-up of 8 years, 121 cases of stroke were identified. Carrying the wild-type allele of the ALDH2 polymorphism increased stroke risk among men. The multivariate hazard ratio [95% confidence interval] of stroke was 2.02 [1.03-3.99] for the wild-type allele compared with the mutant alleles, but the association was attenuated after controlling for alcohol consumption. Combinations of the wild-type allele and other risk factors of stroke, such as old age, diabetes mellitus, and habitual snoring, synergistically increased the risk among men. Among women, however, the ALDH2 polymorphism was not associated with stroke risk.
The prospective cohort study showed a significant association between a common ALDH2 polymorphism and stroke risk in Korean men, but not in Korean women, and also demonstrated that men with genetic disadvantages gain more risk when having risk factors of stroke. Thus, these men may need to make more concerted efforts to control modifiable risk factors of stroke.
PMCID: PMC4317484  PMID: 25671072
ALDH2 polymorphism; alcohol consumption; stroke; prospective study
5.  Association of Obstructive Sleep Apnea and Glucose Metabolism in Subjects With or Without Obesity 
Diabetes Care  2013;36(12):3909-3915.
The purpose of this study was to investigate whether the impact of obstructive sleep apnea (OSA) on glucose metabolism was different according to the presence or absence of obesity.
A total of 1,344 subjects >40 years old from the Korean Genome and Epidemiology Study were included. OSA was detected by home portable sleep monitoring. Plasma glucose, HbA1c, and insulin resistance were compared according to OSA and obesity status. The associations between OSA and impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG + IGT, and diabetes were evaluated in subjects with and without obesity after adjusting for several confounding variables. The effect of visceral obesity on this association was evaluated in 820 subjects who underwent abdominal computed tomography scanning.
In subjects without obesity, fasting glucose, 2-h glucose after 75-g glucose loading, and HbA1c were higher in those with OSA than in those without after controlling for age, sex, and BMI. In addition, the presence of OSA in nonobese subjects was associated with a higher prevalence of IFG + IGT and diabetes after adjusting for several confounding variables (odds ratio 3.15 [95% CI 1.44–6.90] and 2.24 [1.43–3.50] for IFG + IGT and diabetes, respectively). Further adjustment for visceral fat area did not modify this association. In contrast, in those with obesity, none of the abnormal glucose tolerance categories were associated with OSA.
The presence of OSA in nonobese individuals is significantly associated with impaired glucose metabolism, which can be responsible for future risk for diabetes and cardiovascular disease.
PMCID: PMC3836097  PMID: 24101695
6.  Association of Total Marine Fatty Acids, Eicosapentaenoic and Docosahexaenoic Acids, With Aortic Stiffness in Koreans, Whites, and Japanese Americans 
American Journal of Hypertension  2013;26(11):1321-1327.
Few previous studies have reported the association of aortic stiffness with marine n-3 fatty acids (Fas) in the general population. The aim of this study was to determine the combined and independent associations of 2 major marine n-3 FAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), with aortic stiffness evaluated using carotid–femoral pulse wave velocity (cfPWV) in Korean, white, and Japanese American men.
A population-based sample of 851 middle-aged men (299 Koreans, 266 whites, and 286 Japanese Americans) was examined for cfPWV during 2002–2006. Serum FAs, including EPA and DHA, were measured as a percentage of total FAs using gas chromatography. Multiple regression analysis was used to examine the association of EPA and DHA with cfPWV after adjusting for blood pressure and other confounders.
Mean EPA and DHA levels were 1.9 (SD = 1.0) and 4.8 (SD = 1.4) for Koreans, 0.8 (SD = 0.6) and 2.4 (SD = 1.2) for whites, and 1.0 (SD = 1.0) and 3.2 (SD = 1.4) for Japanese Americans. Both EPA and DHA were significantly higher in Koreans than in the other 2 groups (P < 0.01). Multiple regression analyses in Koreans showed that cfPWV had a significant inverse association with total marine n-3 FAs and with EPA alone after adjusting for blood pressure and other potential confounders. In contrast, there was no significant association of cfPWV with DHA. Whites and Japanese Americans did not show any significant associations of cfPWV with total marine n-3 FAs, EPA, or DHA.
High levels of EPA observed in Koreans have an inverse association with aortic stiffness.
PMCID: PMC3790451  PMID: 23820020
aortic stiffness; blood pressure; carotid femoral pulse wave velocity; docosahexaenoic acid; eicosapentaenoic acid; fish oil; hypertension.
7.  Predicting type 2 diabetes using Sasang constitutional medicine 
Sasang constitutional medicine (SCM) has existed in traditional Korean medicine for more than 100 years. SCM consists of four different types: So‐Eum (SE), So‐Yang (SY), Tae‐Eum (TE) and Tae‐Yang (TY). It is of great importance that the Sasang constitution type (SCT) be evaluated accurately and recognized by medical communities.
Materials and Methods
From the Ansung–Ansan prospective cohort study, 10,038 participants were recruited from the years 2001–2002. Of 10,038 original participants, 2,460 participants underwent SCT evaluation. The Cox proportional hazard model was used to predict diabetes during the 10‐year follow‐up period.
During 10 years of follow up (22,007 person‐years), 472 incidence cases (215/10,000 Incidence Density) of type 2 diabetes mellitus were documented. We identified that the TE group was significantly older, more obese, and had higher blood pressure, glucose metabolic values and lipid profiles levels. Relative risk (RR) and 95% confident intervals (CI) for type 2 diabetes were 1.696 (95% CI 1.204–2.39, P = 0.003) for TE when compared with the SE type. After controlling all potential confounders, the Cox proportional hazard model showed that RR was 1.635 (95% CI 1.111–2.406) in non‐obese (body mass index <25) TE, and RR was 1.725 (95% CI 1.213–2.452) in obese (body mass index ≥25) TE when compared with the SE type. We did not find any differences when comparing SE and SY types. The findings shows that TE is a higher risk factor for type 2 Diabetes, independent of obesity level.
The present study suggests that the TE type, independent of obesity level, is a strong risk factor of type 2 diabetes.
PMCID: PMC4188110  PMID: 25411620
Prospective study; Sasang constitutional medicine; Type 2 diabetes mellitus
8.  A cross-sectional association of obesity with coronary calcium among Japanese, Koreans, Japanese Americans, and US Whites 
Conflicting evidence exists regarding whether obesity is independently associated with coronary artery calcium (CAC), a measure of coronary atherosclerosis. We examined an independent association of obesity with prevalent CAC among samples of multi-ethnic groups whose background populations have varying levels of obesity and coronary heart disease (CHD).
Methods and results
We analysed a population-based sample of 1212 men, aged 40–49 years free of clinical cardiovascular disease recruited in 2002–06; 310 Japanese in Japan (JJ), 294 Koreans in South Korea (KN), 300 Japanese Americans (JA), and 308 Whites in the USA (UW). We defined prevalent CAC as an Agatston score of ≥10. Prevalent CAC was calculated by tertile of the body mass index (BMI) in each ethnic group and was plotted against the corresponding median of tertile BMI. Additionally, logistic regression was conducted to examine whether an association of the BMI was independent of conventional risk factors. The median BMI and crude prevalence of CAC for JJ, KN, JA, and UW were 23.4, 24.4, 27.4, and 27.1 (kg/m2); 12, 11, 32, and 26 (%), respectively. Despite the absolute difference in levels of BMI and CAC across groups, higher BMI was generally associated with higher prevalent CAC in each group. After adjusting for age, smoking, alcohol, hypertension, lipids, and diabetes mellitus, the BMI was positively and independently associated with prevalent CAC in JJ, KN, UW, but not in JA.
In this multi-ethnic study, obesity was independently associated with subclinical stage of coronary atherosclerosis among men aged 40–49 years regardless of the BMI level.
PMCID: PMC3738098  PMID: 23764486
Coronary artery calcium; Obesity; Body mass index; Multi-ethnic; Men; Risk factors
9.  Particle Numbers of Lipoprotein Subclasses and Arterial Stiffness among Middle-aged men from the ERA JUMP study 
Journal of human hypertension  2013;28(2):111-117.
We examined the association between serum lipoprotein subclasses and the three measures of arterial stiffness i.e. (i) carotid-femoral pulse wave velocity (cfPWV) which is a gold standard measure of central arterial stiffness, (ii) brachial-ankle PWV (baPWV) which is emerging as a combined measure of central and peripheral arterial stiffness, and (iii) femoral-ankle PWV (faPWV) which is a measure of peripheral arterial stiffness. Among a population-based sample of 701 apparently healthy Caucasian, Japanese American and Korean men aged 40–49 years, concentrations of lipoprotein particles were assessed by nuclear magnetic resonance (NMR) spectroscopy, and PWV was assessed with an automated waveform analyzer (VP2000, Omron, Japan). Multiple linear regressions were performed to analyze the association between each NMR lipoprotein subclasses and PWV measures, after adjusting for cardiovascular risk factors and other confounders. A cut-off of p<0.01 was used for determining significance. All PWV measures had significant correlations with total and small low-density lipoprotein particle number (LDL-P) (all p<0.0001) but not LDL-cholesterol (LDL-C) (all p>0.1), independent of race and age. In multivariate regression analysis, no NMR lipoprotein subclass was significantly associated with cfPWV (all p>0.01). However, most NMR lipoprotein subclasses had significant associations with both baPWV and faPWV (p<0.01). In this study of healthy middle-aged men, as compared to cfPWV, both baPWV and faPWV had stronger associations with particle numbers of lipoprotein subclasses. Our results may suggest that both baPWV and faPWV are related to arterial stiffness and atherosclerosis, whereas cfPWV may represent arterial stiffness alone.
PMCID: PMC3800263  PMID: 23823580
lipoproteins; lipoprotein fractions; pulse wave velocity; atherosclerosis
10.  The Associations of Indices of Obesity with Lipoprotein Subfractions in Japanese American, African American and Korean Men 
Global heart  2013;8(3):273-280.
Both indices of obesity and lipoprotein subfractions contribute to coronary heart disease risk. However, associations between indices of obesity and lipoprotein subfractions remain undetermined across different ethnic groups. This study aims to examine the associations of indices of obesity in Japanese Americans (JA), African Americans (AA) and Koreans with lipoprotein subfractions.
A population-based sample of 230 JA, 91 AA, and 291 Korean men aged 40–49 was examined for indices of obesity, i.e., visceral and subcutaneous adipose tissue (VAT and SAT, respectively), waist circumference (WC), and body-mass index (BMI), and for lipoprotein subfractions by nuclear-magnetic-resonance spectroscopy. Multiple regression analyses were performed in each of the three ethnic groups to examine the associations of each index of obesity with lipoprotein.
VAT had significant positive associations with total and small low-density lipoprotein (LDL) and a significant negative association with large high-density lipoprotein (HDL) in all three ethnicities (p < 0.01). SAT, WC, and BMI had significant positive associations with total and small LDL in only JA and Koreans, while these indices had significant inverse associations with large HDL in all ethnic groups (p < 0.01). Compared to SAT, VAT had larger R2 values in the associations with total and small LDL and large HDL in all three ethnic groups.
VAT is significantly associated with total and small LDL and large HDL in all three ethnic groups. The associations of SAT, WC, and BMI with lipoprotein subfractions are weaker compared to VAT in all three ethnic groups.
PMCID: PMC4110345  PMID: 25068101
visceral adipose tissue; subcutaneous adipose tissue; body-mass index; waist circumference; lipoprotein subfractions
11.  The Prevalence of Aortic Calcification in Japanese Compared to White and Japanese-American Middle-Aged Men is Confounded by the Amount of Cigarette Smoking 
International journal of cardiology  2012;167(1):134-139.
Prevalence of coronary artery calcification (CAC) in Japanese men is lower than in white and Japanese-American men. It is unclear if aortic calcification (AC) strongly linked to smoking is also lower in Japanese men who have many times higher smoking prevalence compared to US men.
We conducted a population-based study of 903 randomly-selected men aged 40–49 years: 310 Japanese men in Kusatsu, Japan, 301 white men in Allegheny County, U.S., and 292 Japanese men in Hawaii, U.S. (2002–2006). The presence of AC was assessed by electron-beam tomography. AC was defined as Agatston aortic calcium scores (AoCaS) >0 and ≥100.
Japanese (35.8%) had significantly less AoCaS>0 compared to both white (68.8%, p<0.001) and Japanese-American (62.3%, p<0.001) but similar AoCaS≥100 (19.4%, 18.3%, 22.6%, respectively, p=0.392). Pack-years of smoking, which was highest in Japanese, was the most important single associate of AC in all populations. Additionally age, low-density-lipoprotein cholesterol (LDL-C), and triglycerides in Japanese; body-mass index (BMI) in white; and BMI, LDL-C, hypertension, diabetes, and lipid medications in Japanese-American were independent associates of AC. The risk of AC using either cut points adjusted for pack-years of smoking and additional risk factors was lower in Japanese compared to both white and Japanese-American. AC and CAC had moderately positive and significant correlations in Japanese (r=0.26), white (r=0.39), and Japanese-American (r=0.45).
Prevalence of AC defined both >0 and ≥100 was significantly lower in Japanese than in white and Japanese-American men after adjusting for cigarette smoking and additional risk factors
PMCID: PMC3328605  PMID: 22240754
Epidemiology; risk factors; atherosclerosis; aorta; calcification; electron-beam tomography; Caucasian; Japanese; Japanese American
12.  Effects of Transglutaminase 2 Inhibition on Ventilator-Induced Lung Injury 
Journal of Korean Medical Science  2014;29(4):556-563.
This study was performed to examine the role of transglutaminase 2 (TG2) in ventilator-induced lung injury (VILI). C57BL/6 mice were divided into six experimental groups: 1) control group; 2) lipopolysaccharide (LPS) group; 3) lung protective ventilation (LPV) group; 4) VILI group; 5) VILI with cystamine, a TG2 inhibitor, pretreatment (Cyst+VILI) group; and 6) LPV with cystamine pretreatment (Cyst+LPV) group. Acute lung injury (ALI) score, TG2 activity and gene expression, inflammatory cytokines, and nuclear factor-κB (NF-κB) activity were measured. TG2 activity and gene expression were significantly increased in the VILI group (P < 0.05). Cystamine pretreatment significantly decreased TG2 activity and gene expression in the Cyst+VILI group (P < 0.05). Inflammatory cytokines were higher in the VILI group than in the LPS and LPV groups (P < 0.05), and significantly lower in the Cyst+VILI group than the VILI group (P < 0.05). NF-κB activity was increased in the VILI group compared with the LPS and LPV groups (P < 0.05), and significantly decreased in the Cyst+VILI group compared to the VILI group (P = 0.029). The ALI score of the Cyst+VILI group was lower than the VILI group, but the difference was not statistically significant (P = 0.105). These results suggest potential roles of TG2 in the pathogenesis of VILI.
Graphical Abstract
PMCID: PMC3991800  PMID: 24753704
Acute Lung Injury; Respiratory Distress Syndrome, Adult; Respiration, Artificial; Ventilator-Induced Lung Injury; Inflammation; Transglutaminase 2
13.  A Case of IgG4-Related Disease Presenting as Massive Pleural Effusion and Thrombophlebitis 
Immunoglobulin (Ig) G4-related disease is a recently recognized systemic fibroinflammatory condition characterized by a lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells with elevated circulating levels of IgG4. The disease can either be localized to one or two organs, or present as diffuse multi-organ disease. Furthermore, lesions in different organs can present simultaneously or metachronously. In the pulmonary manefestations, lesions associated with IgG4-related disease have been described in the lung parenchyma, airways and pleura, as well as the mediastinum. We report a case of IgG4-related disease presenting as massive pleural effusion and thrombophlebitis.
PMCID: PMC4021266  PMID: 24851132
Immunoglobulin G; Pleural Effusion; Thrombophlebitis
14.  Personality Traits and Body Mass Index in a Korean Population 
PLoS ONE  2014;9(3):e90516.
Overweight and obesity is a serious problem worldwide related to cardiovascular and other diseases. Personality traits are associated with the abnormal body mass indices (BMIs) indicative of overweight and obesity. However, the links between personality traits and BMI have been little studied in Korea.
We evaluated the association between personality traits and BMI in men and women using the rural Ansung and urban Ansan cohort from the Korean Genome Epidemiology Study, and the Kangbuk Samsung Hospital Cohort Study datasets. A shorter version of the original Revised Neuroticism-Extroversion-Openness Personality Inventory (NEO-PI-R) was used to measure the five-factor model of personality (neuroticism, extraversion, openness to experience, agreeableness, and conscientiousness).
Data from a total of 1,495 men (mean age 60.0±9.8 years; mean BMI 24.3±3.0 kg/m2) and 2,547 women (mean age 47.0±15.5 years; mean BMI 22.8±3.4 kg/m2) were included in the analysis. Compared with the normal weight groups, overweight and obese men scored higher on openness to experience and lower on conscientiousness. Overweight and obese women scored lower on neuroticism and openness to experience and higher on agreeableness. Extraversion was positively associated with BMI in men (β = 0.032, P<0.05). BMI and waist circumference were significantly increased in individuals who were less dutiful. In women, neuroticism was inversely associated with BMI (β = −0.026, P<0.05). Openness to experience was negatively, and agreeableness was positively, associated with BMI (openness to experience: β = −0.072, agreeableness β = 0.068) and waist circumference (openness to experience: β = −0.202, agreeableness: β = 0.227) (P<0.05).
Personality traits were associated with underweight, overweight, and obesity in men and women. Increased understanding of the underlying factors contributing to this association will aid in the prevention and treatment of abnormal BMI.
PMCID: PMC3944006  PMID: 24598991
15.  Endometrial Stromal Sarcoma Presented as an Incidental Lung Mass with Multiple Pulmonary Nodules 
Low-grade endometrial stromal sarcoma (ESS) is an uncommon gynecologic malignancy of mesodermal origin. Pulmonary metastasis of low-grade ESS can occur years and decades after the treatment of the primary disease. Low-grade ESS is frequently mistaken as benign uterine neoplasm like uterine leiomyoma, which can potentially lead to a misdiagnosis. We present a case of a 42-year-old woman with low-grade ESS, that initially presented as an incidental lung mass with multiple pulmonary nodules, seven years after an uterine myomectomy. A 6.9×5.8 cm-sized intrapelvic mass suspected of uterine origin was discovered while searching for potential extrathoracic primary origin. A pelviscopy and simultaneous thoracoscopic lung biopsy were conducted for pathologic diagnosis. Finally, the diagnosis was confirmed as low-grade ESS with lung metastasis based on the histopathologic examination with immunohistochemical stain, which was showed positive for CD10 and hormone receptor markers (estrogen and progesterone receptors) in both pelvic and lung specimens.
PMCID: PMC3982240  PMID: 24734101
Sarcoma, Endometrial Stromal; Multiple Pulmonary Nodules; Neoplasm Metastasis
16.  Plasma Glucose Regulation and Mortality in Korea: A Pooled Analysis of Three Community-Based Cohort Studies 
Diabetes & Metabolism Journal  2014;38(1):44-50.
Although diabetes is a well-known risk factor for death, its impact on cancer death is not clearly understood. Furthermore, it remains controversial whether impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) are associated with increased risk of mortality. We investigated the impact of diabetes or glucose tolerance categories on all cause and cause-specific mortality.
Mortality analysis was conducted in three population-based cohort studies of 3,801 participants, divided according to fasting plasma glucose (FPG) (normal; stage 1 IFG [5.6≤FPG<6.1 mmol/L]; stage 2 IFG [6.1≤FPG<7.0 mmol/L]; diabetes mellitus [DM]-FPG); or 2-hour glucose after 75 g glucose loading (2hPG) (normal; IGT; DM-2hPG), or a combination of FPG and 2hPG criteria.
During a median follow-up of 11.0 years, 474 subjects died from all causes. Hazard ratios (HRs) for all cause death were higher in those with diabetes as defined by either FPG or 2hPG criteria than their normal counterparts (HR, 2.2, 95% confidence interval [CI], 1.6 to 2.9 for DM-FPG; HR, 2.0, 95% CI, 1.5 to 2.7 for DM-2hPG). Similarly, diabetes defined by either FPG or 2hPG was associated with cancer death (HR, 2.9, 95% CI, 1.7 to 5.0; and HR, 2.1, 95% CI, 1.2 to 3.9, respectively). Although neither IFG nor IGT conferred higher risk for death, when combining stage 2 IFG and/or IGT, the risk of all cause death was higher than in subjects with normal glucose regulation (HR, 1.3; 95% CI, 1.0 to 1.6).
Diabetes is associated with higher risk of death from all causes and cancer. In subjects without diabetes, stage 2 IFG and/or IGT confers increased risk for mortality.
PMCID: PMC3950194  PMID: 24627827
Diabetes mellitus; Glucose intolerance; Mortality
17.  Regional pulse wave velocities and their cardiovascular risk factors among healthy middle-aged men: a cross-sectional population-based study 
Both carotid-femoral (cf) pulse wave velocity (PWV) and brachial-ankle (ba) PWV employ arterial sites that are not consistent with the path of blood flow. Few previous studies have reported the differential characteristics between cfPWV and baPWV by simultaneously comparing these with measures of pure central (aorta) and peripheral (leg) arterial stiffness, i.e., heart-femoral (hf) PWV and femoral-ankle (fa) PWV in healthy populations. We aimed to identify the degree to which these commonly used measures of cfPWV and baPWV correlate with hfPWV and faPWV, respectively, and to evaluate whether both cfPWV and baPWV are consistent with either hfPWV or faPWV in their associations with cardiovascular (CV) risk factors.
A population-based sample of healthy 784 men aged 40–49 (202 white Americans, 68 African Americans, 202 Japanese-Americans, and 282 Koreans) was examined in this cross-sectional study. Four regional PWVs were simultaneously measured by an automated tonometry/plethysmography system.
cfPWV correlated strongly with hfPWV (r = .81, P < .001), but weakly with faPWV (r = .12, P = .001). baPWV correlated moderately with both hfPWV (r = .47, P < .001) and faPWV (r = .62, P < .001). After stepwise regression analyses with adjustments for race, cfPWV shared common significant correlates with both hfPWV and faPWV: systolic blood pressure (BP) and body mass index (BMI). However, BMI was positively associated with hfPWV and cfPWV, and negatively associated with faPWV. baPWV shared common significant correlates with hfPWV: age and systolic BP. baPWV also shared the following correlates with faPWV: systolic BP, triglycerides, and current smoking.
Among healthy men aged 40 – 49, cfPWV correlated strongly with central PWV, and baPWV correlated with both central and peripheral PWVs. Of the CV risk factors, systolic BP was uniformly associated with all the regional PWVs. In the associations with factors other than systolic BP, cfPWV was consistent with central PWV, while baPWV was consistent with both central and peripheral PWVs.
PMCID: PMC3893368  PMID: 24410766
Arterial stiffness; Aorta; Carotid arteries; Brachial artery; Femoral artery
18.  Correlation of a Self-Report and Direct Measure of Physical Activity Level in the Electron-Beam Tomography and Risk Assessment Among Japanese and US Men in the Post World War II Birth Cohort (ERA JUMP) Study 
Journal of Epidemiology  2013;23(6):411-417.
Physical activity (PA) is complex and a difficult behavior to assess as there is no ideal assessment tool(s) that can capture all contexts of PA. Therefore, it is important to understand how different assessment tools rank individuals. We examined the extent to which self-report and direct assessment PA tools yielded the same ranking of PA levels.
PA levels were measured by the Modifiable Activity Questionnaire (MAQ) and pedometer at baseline among 855 white (W), African-American (AA), Japanese-American (JA), and Korean (K) men (mean age 45.3 years) in 3 geographic locations in the ERA JUMP study.
Korean men were more active than W, AA, and JA men, according to both the MAQ and pedometer (MAQ total PA [mean ± SD]: 41.6 ± 17.8, 20.9 ± 9.9, 20.0 ± 9.1, and 29.4 ± 10.3 metabolic equivalent [MET] hours/week, respectively; pedometer: 9584.4 ± 449.4, 8363.8 ± 368.6, 8930.3 ± 285.6, 8335.7 ± 368.6 steps/day, respectively). Higher levels of total PA in Korean men, as shown by MAQ, were due to higher occupational PA. Spearman correlations between PA levels reported on the MAQ and pedometer indicated positive associations ranging from rho = 0.29 to 0.42 for total activity, rho = 0.13 to 0.35 for leisure activity, and rho = 0.10 to 0.26 for occupational activity.
The 2 assessment methods correlated and were complementary rather than interchangeable. The MAQ revealed why Korean men were more active. In some subpopulations it may be necessary to assess PA domains other than leisure and to use more than 1 assessment tool to obtain a more representative picture of PA levels.
PMCID: PMC3834277  PMID: 24064592
ethnic groups; exercise; pedometry; self-report; occupational activity
19.  Total nasal resistance among Sasang constitutional types: a population-based study in Korea 
There have been many attempts to find an objective phenotype by Sasang constitutional types (SCTs) on an anatomical, physiological, and psychological basis, but there has been no research on total nasal resistance (TNR) among SCTs.
We assessed the value of the TNR in the SCTs classified by an integrated diagnostic model. Included in the study were 1,346 individuals (701 males, 645 females) who participated in the Korean Genome and Epidemiology Study (KoGES). The TNR was measured by active anterior rhinomanometry (AAR) at transnasal pressures of 100 and 150 Pascal (Pa).
The average TNR was 0.186 ± 0.004 Pa/cm3/second at 100 Pa in the Tae-eum (TE), 0.193 ± 0.007 in the So-eum (SE), and 0.208 ± 0.005 in the So-yang (SY) types. Under condition of 150 Pa the TE type had a TNR value of 0.217 ± 0.004, the SE type was 0.230 ± 0.008, and the SY type was 0.243 ± 0.005. Higher values of TNR were more likely to be reported in the SY type at 100 Pa and 150 Pa. In the stratified analysis by sex, the SY type in males and females tended to have higher TNR value than the TE and SE types at transnasal pressure of both 100 Pa and 150 Pa.
These results provide new approaches to understand the functional characteristics among the SCTs in terms of nasal physiology. Further studies are required to clarify contributing factors for such a difference.
PMCID: PMC4228428  PMID: 24180585
Sasang constitutional types; Total nasal resistance; Active anterior rhinomanometry; Transnasal pressure; Tae-eum type; So-eum type; So-yang type
20.  Relationships of Coagulation Factor XIII Activity with Cell-Type and Stage of Non-Small Cell Lung Cancer 
Yonsei Medical Journal  2013;54(6):1394-1399.
Factor XIII (FXIII), a thrombin-activated plasma transglutaminase zymogen, is involved in cancer development and progression through a triggered coagulation pathway. The aim of this study was to examine whether FXIII activity levels differed in non-small cell lung cancer (NSCLC) patients according to histological types and TNM stage when compared with healthy subjects.
Materials and Methods
Twenty-eight NSCLC patients and 28 normal controls who had been individually age-, gender-, body mass index-, smoking status-, and smoking amount-matched were enrolled: 13 adenocarcinomas, 11 squamous cell carcinomas, and four undifferentiated NSCLCs; four stage I, two stage II, 12 stage III, and 10 stage IV NSCLCs. FXIII activity was measured using fluorescence-based protein arrays.
The median FXIII activity level of the NSCLC group [24.2 Loewy U/mL, interquartile range (IQR) 14.9-40.4 Loewy U/mL] was significantly higher than that of the healthy group (17.5 Loewy U/mL, IQR 12.6-26.4 Loewy U/mL) (p=0.01). There were no differences in FXIII activity between adenocarcinoma (median 18.6 Loewy U/mL) and squamous cell carcinoma (median 28.7 Loewy U/mL). NSCLC stage significantly influenced FXIII activity (p=0.02). The FXIII activity of patients with stage III NSCLC (median 27.3 Loewy U/mL, IQR 19.3-40.5 Loewy U/mL) was significantly higher than those of patients with stage I or II (median 14.0 Loewy U/mL, IQR 13.1-23.1 Loewy U/mL, p=0.04). FXIII activity was negatively correlated with aPTT in NSCLC patients (r=-0.38, p=0.04).
Patients with advanced-stage NSCLC exhibited higher coagulation FXIII activity than healthy controls and early-stage NSCLC patients.
PMCID: PMC3809885  PMID: 24142643
Factor XIII; histological type; neoplasm staging; non-small-cell lung carcinoma
21.  Low Vitamin D Status Is Associated with Nonalcoholic Fatty Liver Disease Independent of Visceral Obesity in Korean Adults 
PLoS ONE  2013;8(10):e75197.
To investigate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and nonalcoholic fatty liver disease (NAFLD) independent of visceral obesity in Koreans and to examine whether the associations differ according to the presence of diabetes or insulin resistance.
Research Design and Methods
A total of 1081 adults were enrolled from a population-based cohort in Ansan city. Serum 25(OH)D concentrations were measured in all subjects. Insulin resistance was measured by homeostasis model assessment of insulin resistance (HOMA-IR). Using computed tomography, NAFLD was diagnosed if the liver attenuation index (LAI, the difference between the mean hepatic and splenic attenuation) was <5 Hounsfield Units.
In subjects with diabetes (n = 282), 25(OH)D levels were negatively associated with waist circumference, fasting insulin, HOMA-IR, triglyceride levels, and visceral abdominal fat, and were positively associated with LAI after adjusting for age, sex, season, exercise, and vitamin supplementation. In subjects without diabetes, only triglyceride level was negatively associated with 25(OH)D. The adjusted odds ratio (OR) for NAFLD increased sequentially across decreasing quartiles of 25(OH)D in subjects with diabetes even after adjusting for visceral fat [Q1 vs. Q4; OR for NAFLD 2.5 (95% CI:1.0–6.2)]. In contrast, no significant difference in OR was observed in subjects without diabetes. When we classified non-diabetic subjects by HOMA-IR, an increase in the OR for NAFLD across decreasing quartiles of 25(OH)D was observed in the high HOMA-IR (≥2.5) group [n = 207, Q1 vs. Q4; OR 3.8(1.4–10.3)], but not in the low HOMA-IR (<2.5) group [n = 592, OR 0.8 (0.3–1.9)].
Low vitamin D status is closely associated with NAFLD, independent of visceral obesity in subjects with diabetes or insulin resistance.
PMCID: PMC3793981  PMID: 24130687
22.  Serum levels of marine-derived n-3 fatty acids in Icelanders, Japanese, Koreans, and Americans - A descriptive epidemiologic study 
In the 1990’s Iceland and Japan were known as countries with high fish consumption whereas coronary heart disease (CHD) mortality in Iceland was high and that in Japan was low among developed countries. We described recent data fish consumption and CHD mortality from publicly available data. We also measured CHD risk factors and serum levels of marine-derived n-3 and other fatty acids from population-based samples of 1,324 men in Iceland, Japan, South Korea, and the US. CHD mortality in men in Iceland was almost 3 times as high as that in Japan and South Korea. Generally a profile of CHD risk factors in Icelanders compared to Japanese was more favorable. Serum marine-derived n-3 fatty acids in Iceland were significantly lower than in Japan and South Korea but significantly higher than in the US.
PMCID: PMC3404187  PMID: 22658580
n-3 fatty acids; eicosapentaenoic acid; docosaehexaenoic acid; coronary heart disease; descriptive epidemiologic study
23.  The start of chemotherapy until the end of radiotherapy in patients with limited-stage small cell lung cancer 
Chemotherapy combined with radiation therapy is the standard treatment for limited stage small cell lung cancer (LS-SCLC). Although numerous studies indicate that the overall duration of chemoradiotherapy is the most relevant predictor of outcome, the optimal chemotherapy and radiation schedule for LS-SCLC remains controversial. Therefore we analyzed the time from the start of any treatment until the end of radiotherapy (SER) in patients with LS-SCLC.
We retrospectively analyzed 29 patients diagnosed histologically with LS-SCLC and divided them into two groups: a short SER group (< 60 days) and a long SER (> 60 days) group. Patients were treated with irinotecan-based chemotherapy and thoracic radiotherapy.
Sixteen patients were in the short SER group and 13 patients were in the long SER group. Short SER significantly prolonged survival rate (p = 0.03) compared with that of long SER. However, no significant differences in side effects were observed.
Short SER should be considered to improve the outcome of concurrent chemoradiotherapy for LS-SCLC.
PMCID: PMC3712153  PMID: 23864803
Small cell lung carcinoma; Limited-stage; Chemoradiotherapy; Start of any treatment until the end of radiotherapy
24.  Aortic stiffness and calcification in men in a population-based international study 
Atherosclerosis  2012;222(2):473-477.
Aortic stiffness, a hallmark of vascular aging, is an independent risk factor of cardiovascular disease and all-cause mortality. The association of aortic stiffness with aortic calcification in middle-aged general population remains unknown although studies in patients with end-stage renal disease or elderly subjects suggest that aortic calcification is an important determinant of aortic stiffness. The goal of this study was to examine the association of aortic calcification and stiffness in multi-ethnic population-based samples of relatively young men.
We examined the association in 906 men aged 40–49 (81 Black Americans, 276 Japanese Americans, 258 White Americans and 291 Koreans). Aortic stiffness was measured as carotid-femoral pulse wave velocity (cfPWV) using an automated waveform analyzer. Aortic calcification from aortic arch to iliac bifurcation was evaluated using electron-beam computed tomography.
Aortic calcium score was calculated and was categorized into four groups: zero (n=303), 1–100 (n=411), 101–300 (n=110), and 401+ (n=82). Aortic calcification category had a significant positive association with cfPWV after adjusting for age, race, and mean arterial pressure (mean (standard error) of cfPWV (cm/second) from the lowest to highest categories: 836 (10), 850 (9), 877 (17) and 941 (19), p for trend <0.001). The significant positive association remained after further adjusting for other cardiovascular risk factors. The significant positive association was also observed in each race group.
The results suggest that aortic calcification can be one mechanism for aortic stiffness and that the association of aortic calcification with stiffness starts as early as the 40’s.
PMCID: PMC3361615  PMID: 22537531
aortic stiffness; aortic calcification; international multi-ethnic study
25.  A healthy dietary pattern consisting of a variety of food choices is inversely associated with the development of metabolic syndrome 
Nutrition Research and Practice  2013;7(3):233-241.
There are limited data on healthy dietary patterns protective against metabolic syndrome (MetSyn) development. We identified dietary patterns among middle-aged and older adults and investigated the associations with the incidence of MetSyn. A population-based prospective cohort study included 5,251 male and female Koreans aged 40-69 years. At baseline, all individuals were free of MetSyn, other major metabolic diseases, and known cardiovascular disease or cancer. Cases of MetSyn were ascertained over a 6-year of follow-up. Dietary patterns and their factor scores were generated by factor analysis using the data of a food frequency questionnaire. We performed pooled logistic regression analysis to estimate multivariable-adjusted relative risk (RR) and 95% confidence interval (CI) for associations between factor scores and MetSyn risk. Two dietary patterns were identified; (1) a healthy dietary pattern, which included a variety of foods such as fish, seafood, vegetables, seaweed, protein foods, fruits, dairy products, and grains; and (2) an unhealthy dietary pattern, which included a limited number of food items. After controlling for confounding factors, factor scores for the healthy dietary pattern were inversely associated with MetSyn risk (P-value for trend < 0.05) while those for the unhealthy dietary pattern had no association. Individuals in the top quintile of the healthy diet scores showed a multivariable-adjusted RR [95% CI] of 0.76 [0.60-0.97] for MetSyn risk compared with those in the bottom quintile. The beneficial effects were derived from inverse associations with abdominal obesity, low HDL-cholesterol levels, and high fasting glucose levels. Our findings suggest that a variety of healthy food choices is recommended to prevent MetSyn.
PMCID: PMC3679333  PMID: 23766885
Dietary pattern; food choices; metabolic syndrome incidence; prospective study

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