Jin-Young Jeong

Genome-wide association analyses in east Asians identify new susceptibility loci for colorectal cancer

To identify new genetic factors for colorectal cancer (CRC), we conducted a genome-wide association study in east Asians. By analyzing genome-wide data in 2,098 cases and 5,749 controls, we selected 64 promising SNPs for replication in an independent set of samples, including up to 5,358 cases and 5,922 controls. We identified four SNPs with association P values of 8.58 × 10−7 to 3.77 × 10−10 in the combined analysis of all east Asian samples. Three of the four were replicated in a study conducted in 26,060 individuals of European descent, with combined P values of 1.22 × 10−10 for rs647161 (5q31.1), 6.64 × 10−9 for rs2423279 (20p12.3) and 3.06 × 10−8 for rs10774214 (12p13.32 near the CCND2 gene), derived from meta-analysis of data from both east Asian and European-ancestry populations. This study identified three new CRC susceptibility loci and provides additional insight into the genetics and biology of CRC.

The Escherichia coli glucose transporter enzyme IICB(Glc) recruits the global repressor Mlc.

In addition to effecting the catalysis of sugar uptake, the bacterial phosphoenolpyruvate:sugar phosphotransferase system regulates a variety of physiological processes. Exposure of cells to glucose can result in repression or induction of gene expression. While the mechanism for carbon catabolite repression by glucose was well documented, that for glucose induction was not clearly understood in Escherichia coli. Recently, glucose induction of several E.coli genes has been shown to be mediated by the global repressor Mlc. Here, we elucidate a general mechanism for glucose induction of gene expression in E.coli, revealing a novel type of regulatory circuit for gene expression mediated by the phosphorylation state‐dependent interaction of a membrane‐bound protein with a repressor. The dephospho‐form of enzyme IICBGlc, but not its phospho‐form, interacts directly with Mlc and induces transcription of Mlc‐regulated genes by displacing Mlc from its target sequences. Therefore, the glucose induction of Mlc‐regulated genes is caused by dephosphorylation of the membrane‐bound transporter enzyme IICBGlc, which directly recruits Mlc to derepress its regulon.

Dietary intake of folate and alcohol, MTHFR C677T polymorphism, and colorectal cancer risk in Korea

BACKGROUND The incidence of colorectal cancer (CRC) is increasing sharply in Korea, and evidence has suggested the role of dietary methyl supply and related polymorphisms on colorectal carcinogenesis. OBJECTIVE We investigated the association between folate and alcohol intake, methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, and CRC risk in Koreans. DESIGN A total of 787 cases and 656 controls were recruited from 2 university hospitals. Multiple logistic regression models were used to estimate ORs and corresponding 95% CIs. RESULTS MTHFR 677T homozygotes were at a lower risk of CRC (OR: 0.60; 95% CI: 0.46, 0.78 for TT compared with CC/CT). High folate intake was associated with reduced CRC risk (OR: 0.64; 95% CI: 0.49, 0.84 for high compared with low intake), and high alcohol consumption was associated with increased risk of CRC (OR: 1.76; 95% CI: 1.26, 2.46 for high compared with low intake). When data were stratified by the amount of dietary methyl (combined intake of folate and alcohol), those with low-methyl diets had higher risk of CRC (OR: 2.32; 95% CI: 1.18, 4.56) than did those with high-methyl diets among CC/CT carriers, whereas the amount of dietary methyl did not affect the CRC risk among carriers with the TT homozygous variant. This association was stronger in patients with colon cancer than in patients with rectal cancer. CONCLUSION We found that the effect of dietary methyl supply on colorectal carcinogenesis may differ according to MTHFR C677T genotype and the subsite of origin in a Korean population.

Analysis of growth of non-spherical silica particles in a counterflow diffusion flame considering chemical reactions, coagulation and coalescence

Abstract The evolution of non-spherical silica particles in a counterflow diffusion flame has been studied considering the effects of convection, diffusion, thermophoresis, chemical reactions, coagulation and coalescence. The counterflow geometry provides a one-dimensional flow field along the stagnation point streamline which greatly simplifies the analysis of non-spherical particle growth. Flame analysis of multi-step chemical reactions of hydrogen/oxygen including both oxidation and hydrolysis of SiCl 4 has been done to predict flame temperatures, concentrations of gas species and particle generation. The present prediction of flame temperatures was in good agreement with the previous experimental data. Two-dimensional aerosol dynamics in which both particle volume and surface area are independent variables has been then analyzed to obtain the evolution of non-spherical particles which has been compared with the previous experimental data. Several different models of coalescence of silica particles were studied; viscous flow sintering, atomistic diffusion sintering, fast sintering and hybrid sintering models. The use of hybrid sintering model yielded the best agreement with the previous experimental data. Since the collision cross section of non-spherical particles is larger than that of spherical particles having the same volume, coagulation of particles was obviously shown to be enhanced. The important role of axial particle diffusion has been identified in the counterflow diffusion flame. Bi-modal size distributions were obtained at some flame heights.

Gender differences in adiponectin levels and body composition in older adults: Hallym aging study

BackgroundBody composition changes with ageing can influence the adiponectin concentration. However, the component of body composition that is associated with adiponectin concentrations in older adults remains unclear.MethodsThere were 152 males and 168 females aged 65 years or older that participated in the 2010 Hallym Aging Study (HAS). Body composition (assessed by dual energy X-ray absorptiometry; DXA), anthropometric parameters and adiponectin were obtained from all participants. Multivariate linear regression models assessed the association of body fat percentage, regional muscle and bone mineral contents of body composition and waist/height ratio with adiponectin concentration. Age, albumin, testosterone concentration and metabolic parameters were considered as confounding factors.ResultsIn correlation analysis, age was positively associated with adiponectin in males (P < 0.01), but not in females. Fasting glucose, albumin, arm skeletal muscle mass and bone mineral content were negatively associated with adiponectin in males (P < 0.05). Testosterone and leg bone mineral content were negatively associated with adiponectin in females (P < 0.05). In multivariate linear regression models, body fat percentage and albumin (P < 0.05) were negatively associated with adiponectin, and high-density lipoprotein cholesterol (HDL-C) (P < 0.001) and age (P < 0.01) were positively associated with adiponectin in older males. In older females, the only factors that correlated significantly with adiponectin concentration were the homeostasis model assessment of insulin resistance (P < 0.001) and HDL-C (P < 0.05). The waist/height ratio and bone mineral content were not associated with adiponectin in either gender.ConclusionPlasma adiponectin levels correlated negatively with body fat percentage in older males but not in older females. The differential results between older males and females suggest that certain gender-specific mechanisms may affect the association between adiponectin and age-related body composition changes.

Waist circumference, not body mass index, is associated with renal function decline in korean population: hallym aging study.

Background Prospective investigation of obesity and renal function decline in Asia is sparse. We examined the associations of body mass index (BMI) and waist circumference (WC) with renal function decline in a prospective study of Korean population. Methods A total of 454 participants who had baseline estimated glomerular filtration rate (eGFR) levels of more than 60 mL/min/1.73 m2 in Hallym Aging Study (HAS) were included and followed for 6 years. Renal function decline was defined as follows: (1) an eGFR decline ≥3 mL/min/1.73 m2/year (n = 82 cases); (2) an eGFR decrease of 20% or greater (n = 87 cases) at follow-up; (3) an eGFR decrease of 20% greater at follow-up or eGFR decline ≥3 mL/min/1.73 m2/year (n = 91 cases); and (4) an eGFR <60 mL/min/1.73 m2 at follow-up (n = 54 cases). eGFR was determined based on the Modification of Diet in Renal Disease (MDRD) Study equation. Multivariate logistic regression model was used to determine the association between obesity and renal function decline. Results We found that central obesity was associated with faster renal function decline. Comparing WC of >95 cm in men or >90 cm in women with ≤90 cm in men or ≤85 cm in women, ORs (95% CIs) ranged from 2.31 (1.14–4.69) to 2.78 (1.19–6.50) for the 4 definitions of renal function decline (all p-values for trend <0.05). Waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) also was associated with renal function decline. There was no significant association of BMI with renal function decline. Conclusions Central obesity, but not BMI, is associated with faster renal function decline in Korean population. Our results provide important evidence that simple measurement of central fat deposition rather than BMI could predict decline in renal function in Korean population.

Hexagonal RMnO3: a model system for two‐dimensional triangular lattice antiferromagnets

The hexagonal RMnO3(h-RMnO3) are multiferroic materials, which exhibit the coexistence of a magnetic order and ferroelectricity. Their distinction is in their geometry that both results in an unusual mechanism to break inversion symmetry and also produces a two-dimensional triangular lattice of Mn spins, which is subject to geometrical magnetic frustration due to the antiferromagnetic interactions between nearest-neighbor Mn ions. This unique combination makes the h-RMnO3 a model system to test ideas of spin-lattice coupling, particularly when both the improper ferroelectricity and the Mn trimerization that appears to determine the symmetry of the magnetic structure arise from the same structure distortion. In this review we demonstrate how the use of both neutron and X-ray diffraction and inelastic neutron scattering techniques have been essential to paint this comprehensive and coherent picture of h-RMnO3.

The Relationship between Smoking, Socioeconomic Status and Grip Strength among Community-dwelling Elderly Men in Korea: Hallym Aging Study

OBJECTIVES Low grip strength is associated with decline in bone mineral density (BMD) and increased risk of spine fracture among the elderly. Smoking, a major factor determining BMD, is also known to have an indirect effect on bone loss. This study investigated whether smoking is associated with grip strength in the community-dwelling elderly in Korea. METHODS This study was an outcome of the second of three waves of the Hallym Aging Study from January to May 2007, a population-based study of Koreans aged 45 years and upwards dwelling in Chuncheon. Its 218 subjects comprised men aged 65 years or over. They were evaluated at a general hospital for socioeconomic status, smoking history, and various clinical measures including grip strength. RESULTS Grip strength was higher in non-, ex-, and current smokers (33.7 kg, 30.6 kg, and 29.3 kg, respectively). Current smoking was found to increase the risk of decreased grip strength (adjusted odds ratio [aOR], 4.58; 95% confidence interval [CI],1.31 to 16.04) compared with non-smoking, after adjustment for potential covariates including socioeconomic status. After adjustment for smoking effect, education of fewer than six years and monthly income of fewer than 500,000 Korean won increased the risk of decreased grip strength compared with education of more than six years (aOR, 2.88; 95% CI, 1.08 to 7.66) and monthly income of more than 1,500,000 Korean won (aOR, 2.86; 95% CI, 1.08 to 7.54). CONCLUSIONS These results showed that current smoking, low education and low income were independent risk factors for decreased grip strength among elderly men in Korea.

The Relationship between Height and Cognitive Function among Community-dwelling Elderly: Hallym Aging Study

OBJECTIVES Height is known as an index that reflects the environment of the fetal, childhood, and adolescent periods, which affect adult health. This study was conducted to elucidate whether height is associated with cognitive impairment in community-dwelling elders in Korea. METHODS The study subjects were recruited among community dwelling elderly individuals aged 65 or over who participated in the 2004 Hallym Aging Study. They were invited to a general hospital and were evaluated for socioeconomic status, smoking history, and various clinical measures. Cognitive function measurement was performed using the Korean-Mini Mental State Examination. Logistic regression was used to evaluate the association between height and cognitive function. RESULTS After adjusting for potential covariates such as age and education, the smallest group was associated with higher risk of cognitive impairment compared with the tallest group among elderly men (odds ratio [OR], 4.20; 95% confidence interval [CI], 1.02-17.36), but not among elderly women (OR,1.65; 95% CI, 0.62-4.40). CONCLUSIONS The reason for this difference according to sex may be explained by the differential effects of education on cognitive function by sex. A larger population-based prospective cohort study is needed to examine the association between height and cognitive function according to sex.

[The association of central obesity with type 2 diabetes among Koreans according to the serum gamma-glutamyltransferase level: Korean genome and epidemiology study].

OBJECTIVES This cross-sectional study was performed to examine if the serum gamma-glutamyltransferase (GGT) level that is within its normal range is associated with the risk of type 2 diabetes and if the association between the waist hip ratio (WHR) and type 2 diabetes is different depending on the serum GGT levels. METHODS The study subjects were 23,436 persons aged 40 years or older and who participated in regular health check-ups at 11 hospitals (males: 5,821, females: 17,615). The gender-specific quintiles of the serum GGT and WHR were used to examine the associations with type 2 diabetes. RESULTS The serum GGT levels within their normal range were positively associated with type 2 diabetes only in women. The adjusted odds ratios (ORs) were 1.0, 1.0, 1.4, 2.1, and 2.5 according to the quintiles of the serum GGT (p(trend)<0.01). The WHR was more strongly associated with the prevalence of diabetes among the women with a high-normal serum GGT level as compared with those with a low-normal serum GGT level (p for interaction=0.02). For example, the adjusted ORs for women with a low normal serum GGT level were 1.0, 1.2, 1.5, 2.2, and 2.4 according to the quintiles of the WHR, while those figures were 1.0, 2.4, 3.6, 5.0, and 8.3 among the women with a high normal serum GGT level. However, in men, the serum GGT was very weakly associated with type 2 diabetes and the association between the WHR and type 2 diabetes was not different depending on the serum GGT level. CONCLUSIONS Serum GGT within its normal range was positively associated with type 2 diabetes, and central obesity was more strongly associated with the prevalence of type 2 diabetes when the serum GGT level was high-normal. However, these associations were observed only in women, which is different from the previous findings. The stronger relation between central obesity and type 2 diabetes among women with a high-normal serum GGT level can be useful for selecting a group that is at high risk for type 2 diabetes irregardless of whatever the underlying mechanism is.