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result(s) for
"Shin, Young-Chul"
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Subclinical Hypothyroidism and Incident Depression in Young and Middle-Age Adults
2018
Abstract
Background
The role of subclinical hypothyroidism in the development of depression remains controversial. We examined the prospective association between subclinical hypothyroidism and incident depressive symptoms.
Methods
We conducted a prospective cohort study of 220,545 middle-age adults without depression who had undergone at least two comprehensive health examinations between 1 January 2011 and 31 December 2014. Thyroid-stimulating hormone, free triiodothyronine (FT3), and free thyroxine (FT4) levels were measured using an electrochemiluminescent immunoassay. The study outcome was incident depressive symptoms, defined as a Center for Epidemiologic Studies-Depression score >16.
Results
During a median follow-up period of 2 years, incident depressive symptoms occurred in 7323 participants. The multivariable-adjusted hazard ratio for incident depressive symptoms comparing subclinical hypothyroid and euthyroid participants was 0.97 (95% confidence interval, 0.87 to 1.09). Similarly, among euthyroid participants (n = 87,822), no apparent association was found between thyroid hormone levels and an increased risk of incident depressive symptoms.
Conclusions
No apparent association was found between subclinical hypothyroidism and incident depressive symptoms in a large prospective cohort of middle-age men and women.
We examined the prospective association between subclinical hypothyroidism and depression in a large cohort of middle-aged healthy men and women and found no apparent association.
Journal Article
Deformation Behavior and Microstructure of 6061 Aluminum Alloy Processed by Severe Plastic Deformation Using Biaxial Alternate Forging
2024
The deformation behavior and microstructure of 6061 aluminum alloy processed by severe plastic deformation (SPD) using biaxial alternate forging that can evaluate the forming limit and mechanical properties of alloys, simultaneously, were investigated in this study. A finite element (FE) analysis on the biaxial alternating forging process, considering the strain-hardening coefficient and forging pass of the material, was conducted. When the strain-hardening coefficient is 0, an average effective strain of 440% was found within a diameter of 4 mm in the core of the workpiece after eight passes, while it was 300% at the same pass number when the strain-hardening coefficient was 0.2. The average effective strain estimated from the FE analysis was about 264% after eight passes of forging, which is considered to be a level of SPD that significantly exceeds the elongation of the raw material. As a result of the tensile test according to the forging pass, after two passes, the strength of the material could be gradually improved without significant degradation of elongation. Even though a large strain of 264% was found after eight passes were applied, deformed grains and twins with no recrystallized structure in optical microstructures with different forging passes were found.
Journal Article
Association between work stress and risk of suicidal ideation
2020
Objective The aim of this study was to identify work stress associated with the development of suicidal ideation with a focus on gender and age differences among Korean employees. Methods The data of 95 356 healthy employees aged >18 years who had undergone at least two comprehensive health examinations at Kangbuk Samsung Hospital Health Screening Center, South Korea, were analyzed. Risk of suicidal ideation was assessed using a self-reported questionnaire examining suicidal ideation during the past year. Work stress was measured using the Korean Occupational Stress Scale-Short Form. A Cox proportional hazards model was used to examine relationship between work stress and suicidal ideation. Considering gender and age differences in the association between work stress and suicidal ideation, the data were stratified by gender and age groups. Results During 289 706 person-years of follow-up, suicide ideation was identified in 3 460 participants. For male workers, high job demands and lack of reward were associated with the risk of suicidal ideation in young adults and midlife decade group. Job insecurity was associated with the risk of suicidal ideation in midlife decade and middle-aged and older adulthood. Organizational injustice was associated with the risk of suicidal ideation in middle-aged and older adulthood. Discomfort in an organizational climate was associated with the development of suicidal ideation in all age groups. For female workers, organizational injustice and discomfort in an organizational climate were associated with the risk of suicidal ideation in early adulthood. Conclusion The results suggested that certain work stressors are risk factors of suicidal ideation. Gender and age differences in components of work stress associated with suicidal ideation were also observed.
Journal Article
TEM investigation on microstructures of age-hardened 2014 Al alloy forged by cold biaxial alternate forging
2024
In this study, microstructures of age-hardened 2014 Al alloy forged by cold biaxial alternate forging was investigated by transmission electron microscope. And also, the forming limits of age-hardened 2014 Al alloy were examined using both conventional compression test and biaxial alternate forging. As a result of compression test, it showed a perfect plastic behavior with no visible change in stress after 27% in strain and eventually, the curve fluctuated as a shear crack occurs after 51% strain. However, it was possible to impose very large strains on the 2014-T6 Al alloy workpieces through the biaxial alternate forging of up to 4 passes. The effective strain was possibly accumulated to 356% and 204% as the maximum and average values, respectively. The results of transmission electron microscope indicated that the high density dislocations were distributed after 3 passes. After 4 passes, the distribution of more increased dislocations was observed and band-shaped dislocation clustering appeared.
Journal Article
Imaging the Raf–MEK–ERK Signaling Cascade in Living Cells
2024
Conventional biochemical methods for studying cellular signaling cascades have relied on destructive cell disruption. In contrast, the live cell imaging of fluorescent-tagged transfected proteins offers a non-invasive approach to understanding signal transduction events. One strategy involves monitoring the phosphorylation-dependent shuttling of a fluorescent-labeled kinase between the nucleus and cytoplasm using nuclear localization, export signals, or both. In this paper, we introduce a simple method to visualize intracellular signal transduction in live cells by exploring the translocation properties of PKC from the cytoplasm to the membrane. We fused bait protein to PKC, allowing the bait (RFP-labeled) and target (GFP-labeled) proteins to co-translocate from the cytoplasm to the membrane. However, in non-interacting protein pairs, only the bait protein was translocated to the plasma membrane. To verify our approach, we examined the Raf–MEK–ERK signaling cascade (ERK pathway). We successfully visualized direct Raf1/MEK2 interaction and the KSR1-containing ternary complex (Raf1/MEK2/KSR1). However, the interaction between MEK and ERK was dependent on the presence of the KSR1 scaffold protein under our experimental conditions.
Journal Article
Altered Brain Activity during Reward Anticipation in Pathological Gambling and Obsessive-Compulsive Disorder
by
Shin, Young-Chul
,
Choi, Chi-Hoon
,
Jung, Wi Hoon
in
Activation
,
Addictions
,
Addictive behaviors
2012
Pathological gambling (PG) and obsessive-compulsive disorder (OCD) are conceptualized as a behavioral addiction, with a dependency on repetitive gambling behavior and rewarding effects following compulsive behavior, respectively. However, no neuroimaging studies to date have examined reward circuitry during the anticipation phase of reward in PG compared with in OCD while considering repetitive gambling and compulsion as addictive behaviors.
To elucidate the neural activities specific to the anticipation phase of reward, we performed event-related functional magnetic resonance imaging (fMRI) in young adults with PG and compared them with those in patients with OCD and healthy controls. Fifteen male patients with PG, 13 patients with OCD, and 15 healthy controls, group-matched for age, gender, and IQ, participated in a monetary incentive delay task during fMRI scanning. Neural activation in the ventromedial caudate nucleus during anticipation of both gain and loss decreased in patients with PG compared with that in patients with OCD and healthy controls. Additionally, reduced activation in the anterior insula during anticipation of loss was observed in patients with PG compared with that in patients with OCD which was intermediate between that in OCD and healthy controls (healthy controls < PG < OCD), and a significant positive correlation between activity in the anterior insula and South Oaks Gambling Screen score was found in patients with PG.
Decreased neural activity in the ventromedial caudate nucleus during anticipation may be a specific neurobiological feature for the pathophysiology of PG, distinguishing it from OCD and healthy controls. Correlation of anterior insular activity during loss anticipation with PG symptoms suggests that patients with PG fit the features of OCD associated with harm avoidance as PG symptoms deteriorate. Our findings have identified functional disparities and similarities between patients with PG and OCD related to the neural responses associated with reward anticipation.
Journal Article
Gender and age differences in the association between work stress and incident depressive symptoms among Korean employees: a cohort study
by
Young-Chul, Shin
,
Cho, Sung Joon
,
Sang-Won, Jeon
in
Age differences
,
Cohort analysis
,
Confidence intervals
2020
PurposeThe aim of this study was to identify gender- and age-specific occupational stress associated with depressive symptoms among Korean employees.MethodsData of 73,014 employees aged 18 and above who had undergone comprehensive health examinations at Kangbuk Samsung Hospital Health Screening Center, South Korea, in January 2012 and who were followed up until December 2017 were collected, and 63,959 (participation rate: 87.59%, men: 50,413, women: 13,546) were finally analyzed. A Cox proportional hazards model was used to estimate the hazard ratios and 95% confidence intervals of the relationship between occupational stress and depressive symptoms. In light of gender and age differences in the association between occupational stress and depressive symptoms, interaction and stratification by gender and age groups were tested.ResultsDuring 238,630 person-years of follow-up, case-level depressive symptoms developed in 4227 participants (an incident rate of 1.8%). There were gender differences in the relationship between job stress and incident depressive symptoms. For men, high job demand, job insecurity, lack of reward, and discomfort in their organizational climate were associated with incident depressive symptoms in all age groups. Insufficient job control was associated with the development of depressive symptoms only in midlife and organizational injustice only in early adulthood. For women, the results for high job demand, organizational injustice, and discomfort in an organizational climate were associated with the onset of depressive symptoms from early adulthood to the midlife decade.ConclusionThe results suggest gender and age differences in the relationship between occupational stress and incident depressive symptoms.
Journal Article
Bidirectional association between blood pressure and depressive symptoms in young and middle-age adults: A cohort study
by
Shin, Dong-Won
,
Cho, Juhee
,
Oh, Kang-Seob
in
Blood pressure
,
Body mass index
,
Cohort analysis
2020
AimsTo evaluate the bidirectional relationship between blood pressure (BP) and depressive symptoms using a large prospective cohort study.MethodsProspective cohort study was performed in 276 244 adults who participated in a regular health check-up and were followed annually or biennially for up to 5.9 years. BP levels were categorised according to the 2017 American College of Cardiology and American Heart Association hypertension guidelines. Depressive symptoms were assessed using Centre for Epidemiologic Studies-Depression (CESD) questionnaire and a cut-off score of ≥25 was regarded as case-level depressive symptoms.ResultsDuring 672 603.3 person-years of follow-up, 5222 participants developed case-level depressive symptoms. The multivariable-adjusted hazard ratios (HRs) [95% confidence interval (CI)] for incident case-level depressive symptoms comparing hypotension, elevated BP, hypertension stage 1 and hypertension stage 2 to normal BP were 1.07 (0.99–1.16), 0.93 (0.82–1.05), 0.89 (0.81–0.97) and 0.81 (0.62–1.06), respectively (p for trend <0.001). During 583 615.3 person-years of follow-up, 27 787 participants developed hypertension. The multivariable-adjusted HRs (95% CI) for incident hypertension comparing CESD 16–24 and ⩾25 to CESD < 16 were 1.05 (1.01–1.11) and 1.12 (1.03–1.20), respectively (p for trend <0.001) and in the time-dependent models, corresponding HRs (95% CI) were 1.12 (1.02–1.24) and 1.29 (1.10–1.50), respectively (p for trend <0.001).ConclusionsIn this large cohort study of young and middle-aged individuals, higher BP levels were independently associated with a decreased risk for developing case-level depressive symptoms and depressive symptoms were also associated with incident hypertension. Further studies are required to elucidate the mechanisms underlying the bidirectional association between BP levels and incident depression.
Journal Article
Effects of SPD by Biaxial Alternate Forging on the Tensile Properties and Microstructure of AZ31B Magnesium Alloy
by
Shah, Abdul Wahid
,
Ha, Seong-Ho
,
Shin, Young-Chul
in
Aluminum
,
Deformation effects
,
Dislocation density
2023
The forming limit of AZ31 alloy, a representative Mg-Al-Zn-based wrought alloy, and the effect of severe plastic deformation (SPD) by examining the microstructure change caused by dynamic recrystallization led by high temperature and high dislocation density at 300℃ using a biaxial alternate forging (BAF) were investigated in this study. As a result of BAF test for AZ31 Mg alloy, significant cracks on the ends of workpieces occurred after 7 passes. The microstructure of as-extruded specimen showed the non-uniform distribution of the relatively coarse grains and the fine grains considered to be sub-grains. However, as the number of passes increases, the area of coarse grains gradually disappeared and the fine grains became more dominant in the microstructures. The result of tensile test for workpieces with each forging pass showed an increase in strength depending on pass number was shown with a slight increase of elongation. The Electron Backscatter Diffraction (EBSD) results exhibited that, the microstructure showed the presence of coarse grains and twins after only 1 pass, while the grains appeared to be significantly refined and uniformly distributed after 3 pass, at which the strength and elongation began to increase, simultaneously.
Journal Article
Gender Differences in the Association between Workplace Bullying and Depression among Korean Employees
2023
Workplace bullying is a prevalent issue with a significant impact on employees’ mental health. This study aimed to explore the relationship between workplace bullying and the prevalence of depression, with a particular focus on the role of gender. A total of 12,344 Korean employees aged 19–65 years were included in the study. They completed the Center for Epidemiologic Studies Depression Scale (CES-D) and a score of 16 or higher in CES-D indicated depression. The association between workplace bullying and depression was analyzed using logistic regression analyses. The average CES-D scores were higher for both male and female employees who experienced bullying than for those who did not (p < 0.001). The association between the experience of workplace bullying and the prevalence of depression was statistically significant for both genders, with a stronger correlation observed among male employees (p for interaction < 0.001). Organizations are urged to address workplace bullying, particularly for male employees, through the implementation of anti-bullying strategies and policies, as well as the provision of mental health resources and support.
Journal Article