Hospital admission risks and excess costs for neurological symptoms attributable to long-term exposure to fine particulate matter in New York State, USA.

BACKGROUND: Although emerging evidence suggests that PM2.5 is linked to neurological symptoms (NSs) via neuroinflammation, relevant studies are scarce. This study aimed to investigate the risks and excess costs of hospital admission for five NSs-fatigue, headache, dizziness, convulsion, and paralysis-attributable to long-term exposure to PM2.5 in New York State, USA. METHODS: We analyzed the New York Statewide Planning and Research Cooperative System (SPARCS) from 2010 to 2016. A Bayesian hierarchical model with integrated nested Laplace approximations was performed to estimate the risks and excess costs of hospital admission for NSs due to long-term exposure to PM2.5 at the county level. RESULTS: A 1 µg/m3 increase in lag 0-1 years PM2.5 was associated with an increased risk of headache and convulsion by 1.06 (1.01, 1.11) and 1.04 (1.01, 1.06), respectively. The excess hospital admission cost for five NSs attributable to lag 0-1 years PM2.5 above the new World Health Organization guideline (annual standard: 5 µg/m3) was $200.24 (95% CI: 6.00, 376.96) million during 2011-2016, recording the highest for convulsion ($153.73 [95% CI: 63.61, 244.19] million). CONCLUSIONS: This study provides quantitative estimates of risks and excess costs for NSs attributable to long-term PM2.5 and suggests that policies that reduce long-term PM2.5 concentration in accordance with the new WHO air quality guidelines can yield substantial health and economic benefits related to NSs in the New York State population.

Evaluation of Silk Fibroin/Gellan Gum Hydrogels with Controlled Molecular Weight through Silk Fibroin Hydrolysis for Tissue Engineering Application.

Hydrogel is a versatile material that can be manipulated to achieve the desired physicochemical properties, such as stiffness, pore size, and viscoelasticity. Traditionally, these properties have been controlled through parameters such as concentration and pH adjustments. In this study, we focused on exploring the potential of hydrolyzed silk fibroin (HSF) as a molecular weight-modulating agent to control the physicochemical properties of double-composite hydrogels. We developed a synergistic dual-crosslinked hydrogel by combining ionically crosslinked silk fibroin with gellan gum (GG). The hydrolysis of silk fibroin not only enhanced its hydrophilicity but also enabled adjustments in its mechanical properties, including the pore size, initial modulus elasticity, and relaxation time. Moreover, biocompatibility assessments based on cell viability tests confirmed the potential of these hydrogels as biocompatible materials. By highlighting the significance of developing an HSF/GG dual-crosslinked hydrogel, this study contributes to the advancement of novel double-composite hydrogels with remarkable biocompatibility. Overall, our findings demonstrate the capability of controlling the mechanical properties of hydrogels through molecular weight modulation via hydrolysis and highlight the development of a biocompatible HSF/GG dual-crosslinked hydrogel with potential biomedical applications.

Protein arginine methyltransferase 1 contributes to the development of allergic rhinitis by promoting the production of epithelial-derived cytokines.

BACKGROUND: Arginine methylation is a posttranslational modification mediated by protein arginine methyltransferases (PRMTs). Although previous studies have shown that PRMT1 contributes to the severity of allergic airway inflammation or asthma, the underlying mechanism is poorly understood. OBJECTIVE: This study aimed to explore the role of PRMT1 and its relevant mechanism in the development of allergic rhinitis (AR). METHODS: The expression levels of PRMTs and cytokines were determined by RT-PCR, and the localization of PRMT1 was determined by immunohistochemistry and confocal microscopy. The levels of house dust mite (HDM)-specific immunoglobulins in serum and of cytokines in nasal lavage fluids were determined by ELISA. PRMT1 inhibition was achieved by siRNA and treatment with the pan PRMT inhibitor arginine N-methyltransferase inhibitor-1. RESULTS: PRMT1 expression was significantly increased in the nasal mucosa of patients and mice with AR. The degree of eosinophilic infiltration in the nasal mucosa was reduced in PRMT1+/- AR mice compared with wild-type mice. PRMT1 haploinsufficiency reduced the levels of HDM-specific immunoglobulins in serum and those of TH2 (IL-4, IL-5, and IL-13) and epithelial (thymic stromal lymphopoietin [TSLP], IL-25, and IL-33) cytokines in the nasal lavage fluids of AR mice. In nasal epithelial cells, HDM and IL-4 cooperate to enhance PRMT1 expression through a mitogen-activated protein kinase-dependent pathway. In addition, PRMT1 was essential for the production of TSLP, IL-25, and IL-33 in response to HDM and IL-4. Arginine N-methyltransferase inhibitor-1 treatment alleviated AR in the mouse model. CONCLUSIONS: PRMT1 plays an important role in AR development by regulating epithelial-derived cytokine production and might be a new therapeutic target for AR.

Multiple airborne allergen-induced eosinophilic chronic rhinosinusitis murine model.

PURPOSE: Several murine models have been established to mimic human eosinophilic chronic rhinosinusitis (ECRS). However, in most of these models, ECRS was induced using ovalbumin, which does not cause sinusitis in humans. Thus, we aimed to develop a more clinically relevant murine model of ECRS using multiple airborne allergens. We also investigated the effects of exposure duration of the allergens on ECRS development. METHODS: C57BL/6 mice were intranasally administered multiple airborne allergens (house dust mite, Aspergillus fumigatus, Alternaria alternata, and protease from Staphylococcus aureus) three times weekly for 4, 8, 12, and 16 consecutive weeks. Histopathological changes, the levels of cytokines and chemokines in the nasal lavage fluid, and immune cells of the blood and spleen were analyzed. RESULTS: The mice administered multiple allergens showed significantly increased eosinophil infiltration, epithelial thickening and disruption, and subepithelial collagen deposition from 8 weeks compared to the control group. Goblet cell hyperplasia, polyp-like lesions, and blood eosinophils, as well as the levels of interleukin-5 and eotaxin in the nasal lavage fluid were considerably increased in the ECRS group from 12 weeks compared to those of controls. Instillation of allergens for 16 weeks exacerbated the eosinophil infiltration and eotaxin increase in the nasal lavage fluid. CONCLUSIONS: We successfully established a new murine model of ECRS using more clinically relevant multiple airborne allergens. Prolonged exposure to airborne allergens for 12 weeks or more, corresponding to the definition of human ECRS, strongly induced eosinophil infiltration as well as epithelial remodeling.

Hypoxia Modulates Epithelial Permeability via Regulation of Vascular Endothelial Growth Factor in Airway Epithelia.

Hypoxia resulting from occlusion of the sinus ostium is known to be one of the major pathogenic mechanisms of sinusitis. Hypoxia-inducible factor (HIF)-1 is a widely known transcription factor that induces the cellular response to hypoxic conditions and activates the transcription of several genes, including vascular endothelial growth factor (VEGF). We hypothesized that induced permeability caused by hypoxia is a major pathophysiologic mechanism of upper airway diseases, such as sinusitis. The aim of this study was to investigate the mechanism of hypoxia-induced hyperpermeability, which mediates increased paracellular permeability and enhanced microbial invasiveness in the airway epithelium. We show that expression of VEGF mRNA and protein and HIF-1α protein increased as a function of time under hypoxia in normal human nasal epithelial cells. Our results also indicate that VEGF expression was induced by transfection with a mammalian expression vector encoding HIF-1 but down-regulated by transfection with small interfering RNA specific for HIF-1α under hypoxic conditions. Results of a transepithelial permeability assay measuring transepithelial electrical resistance indicated that permeability was increased as a function of time under hypoxia and was rescued by anti-VEGF monoclonal antibody (bevacizumab) and small interfering RNA specific for HIF-1α. We detected up-regulated HIF-1α and VEGF expression in mucosal epithelium samples from patients with sinusitis compared with normal mucosal epithelium using Western blotting and immunohistochemical staining. In conclusion, we suggest that the hypoxia-HIF-1α-VEGF axis plays an important role in hyperpermeability of airway epithelial cells, implying a role in the pathophysiology of upper respiratory tract diseases, such as sinusitis.

Application of a non-hazardous vital dye for cell counting with automated cell counters.

Recent advances in automated cell counters enable us to count cells more easily with consistency. However, the wide use of the traditional vital dye trypan blue (TB) raises environmental and health concerns due to its potential teratogenic effects. To avoid this chemical hazard, it is of importance to introduce an alternative non-hazardous vital dye that is compatible with automated cell counters. Erythrosin B (EB) is a vital dye that is impermeable to biological membranes and is used as a food additive. Similarly to TB, EB stains only nonviable cells with disintegrated membranes. However, EB is less popular than TB and is seldom used with automated cell counters. We found that cell counting accuracy with EB was comparable to that with TB. EB was found to be an effective dye for accurate counting of cells with different viabilities across three different automated cell counters. In contrast to TB, EB was less toxic to cultured HL-60 cells during the cell counting process. These results indicate that replacing TB with EB for use with automated cell counters will significantly reduce the hazardous risk while producing comparable results.

Mental health of single fathers living in an urban community in South Korea.

OBJECTIVE: The aims of this study were to understand the mental health of single fathers relative to married fathers as the population of single fathers continues to increase and to use the resultant data for the establishment of public health policies. METHODS: We evaluated the mental health of 58 single fathers and 256 married fathers living in an urban community in South Korea. Self-reported questionnaires including the Global Assessment of Recent Stress, Center for Epidemiologic Studies-Depression, Scale for Suicidal Ideation, the Korean version of the Alcohol Use Disorder Identification Test, and the World Health Organization Quality of Life Assessment Instrument were used for evaluation. The mental health scale scores and the prevalence of mental health problems were compared between the single and the married fathers. We also assessed the factors associated with poor QOL, depressive symptoms, and severe stress among single fathers. RESULTS: The single fathers had poorer quality of life (OR 7.30, 95% CI 2.82-18.74), more depressive symptoms (OR 3.85, 95% CI 1.29-11.45), and more stress (OR 3.36, 95% CI 1.25-8.98) than did the married fathers even after controlling for socio-demographic factors. Among the single fathers, poor socioeconomic conditions, such as no house ownership, manual occupations, having two or more children, and having a youngest child in elementary school or middle school, were significantly associated with poorer mental health. CONCLUSIONS: This study demonstrated that single fathers have poorer mental health than do married fathers. Single parenthood was significantly associated with their mental health. Therefore, we should attempt to provide practical support to reduce the social burden and offer earlier psychological interventions to reduce distress in single fathers.

Nanomechanical Analysis of a UV Treated Ag Thin Film Based on a Three-Step Oxidation Model.

Nanoindentation was used as the main method to measure the change in nanomechanical properties on the surface of an Ag thin film due to UV treatment. The 4-point probe method, X-ray diffraction (XRD), and atomic force microscopy (AFM) were used to measure the electrical, crystallographic, and morphological properties, respectively. During a UV treatment time of between 1 and 3 minutes, the sheet resistance increased dramatically to 0.55 Ω/sq. (the sheet resistance was 0.16 Ω/sq. prior to UV treatment) and these results were supported by a proportional decreased in XRD intensity. Thereafter, the sheet resistance decreased and the XRD intensity increased in response to increases in UV treatment time. These results were related to a change in crystal structure from Ag to AgOx, which could also have caused the change in sheet resistance. Based on these results, we propose a 3-step oxidation model of an Ag thin film according to UV treatment time. This proposal has been proven by nanoindentation testing.

Simiduia curdlanivorans sp. nov., a curdlan-degrading bacterium isolated from the junction between the ocean and a freshwater spring, and emended description of the genus Simiduia.

A Gram-stain-negative, aerobic, non-spore-forming, non-flagellated and rod-shaped bacterial strain, designated DMCK3-4(T), was isolated from the zone where the ocean and a freshwater spring meet at Jeju island, South Korea. Strain DMCK3-4(T) grew optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0% (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain DMCK3-4(T) clustered with the strains of three members of the genus Simiduia, with which it exhibited 97.0-99.0% sequence similarity. Sequence similarities to the type strains of the other species with validly published names were less than 92.2%. Strain DMCK3-4(T) contained Q-8 as the predominant ubiquinone and summed feature 3 (C(16:1)ω7c and/or C(16:1)ω6c), C(17:1)ω8c, C(16:0), C(17:0) and C(18:1)ω7c as the major fatty acids. The major polar lipids of strain DMCK3-4(T) were phosphatidylethanolamine, phosphatidylglycerol, two unidentified glycolipids, one unidentified lipid and one unidentified aminolipid. The DNA G+C content of strain DMCK3-4(T) was 51.8 mol% and its mean DNA-DNA relatedness values with Simiduia agarivorans KCTC 23176(T), Simiduia areninigrae KCTC 23293(T) and Simiduia litorea NRIC 0917(T) were 23-34%, respectively. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain DMCK3-4(T) is distinct from other species of the genus Simiduia. On the basis of the data presented, strain DMCK3-4(T) is considered to represent a novel species of the genus Simiduia, for which the name Simiduia curdlanivorans sp. nov. is proposed. The type strain is DMCK3-4(T) ( = KCTC 42075(T) =CECT 8570(T)). An emended description of the genus Simiduia is also proposed.

Simiduia aestuariiviva sp. nov., a gammaproteobacterium isolated from a tidal flat sediment.

A Gram-stain negative, aerobic, motile and rod-shaped bacterial strain, designated J-MY2(T), was isolated from a tidal flat sediment of the South Sea, South Korea. Strain J-MY2(T) was found to grow optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain J-MY2(T) forms a cluster with the type strains of Simiduia species. Strain J-MY2(T) exhibited 16S rRNA gene sequence similarity values of 97.62-98.77 % to the type strains of four Simiduia species and of <92.95 % sequence similarity to the type strains of the other recognized species. Strain J-MY2(T) was found to contain Q-8 as the predominant ubiquinone and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0, C18:1 ω7c and C17:1 ω8c as the major fatty acids. The major polar lipids of strain J-MY2(T) were identified as phosphatidylethanolamine, phosphatidylglycerol, three unidentified glycolipids and one unidentified lipid. The DNA G+C content of strain J-MY2(T) was determined to be 54.8 mol% and its mean DNA-DNA relatedness values with the type strains of the four Simiduia species were in the range 21-34 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain J-MY2(T) is separated from other Simiduia species. On the basis of the data presented, strain J-MY2(T) is considered to represent a novel species of the genus Simiduia, for which the name Simiduia aestuariiviva sp. nov. is proposed. The type strain is J-MY2(T) ( = KCTC 42073(T) = CECT 8571(T)).

Sungkyunkwania multivorans gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from seawater from a seaweed farm.

A Gram-staining-negative, non-flagellated, non-gliding and rod-shaped bacterial strain, designated PDB-16(T), was isolated from seawater from a seaweed farm on the South Sea in Korea, and its taxonomic position was investigated using a polyphasic approach. Strain PDB-16(T) grew optimally at 30 °C, at pH 7.0-7.5 and in the presence of 2% (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain PDB-16(T) formed an independent lineage within the evolutionary radiation encompassed by the family Flavobacteriaceae. Strain PDB-16(T) contained MK-6 as the predominant menaquinone and iso-C15:0, iso-C15:1 G and iso-C17:0 3-OH as the major fatty acids. The major polar lipids detected in strain PDB-16(T) were phosphatidylethanolamine and two unidentified lipids. The DNA G+C content of strain PDB-16(T) was 42.1 mol%. Strain PDB-16(T) exhibited very low 16S rRNA gene sequence similarities of less than 89.7% to the type strains of any bacterial species with validly published names and less than 90.1% to uncultured bacteria clones. The 16S rRNA gene sequence similarity values and the differences in phenotypic properties between strain PDB-16(T) and some phylogenetically related genera were sufficient to support the proposal that strain PDB-16(T) should be distinguished from previously known genera of the family Flavobacteriaceae. On the basis of the data presented, strain PDB-16(T) is considered to represent a new genus and novel species, for which the name Sungkyunkwania multivorans gen. nov., sp. nov. is proposed. The type strain of Sungkyunkwania multivorans is PDB-16(T) (=KCTC 32138(T)=CCUG 62952(T)).

Thalassococcus lentus sp. nov., an alphaproteobacterium isolated from seawater of a seaweed farm.

A Gram-negative, non-motile and rod- or ovoid-shaped bacterial strain, designated YCS-24(T), was isolated from seawater of a seaweed farm in the South Sea, South Korea. Strain YCS-24(T) grew optimally at 25-28 °C, at pH 7.0-7.5 and in the presence of 2 % (w/v) NaCl. Strain YCS-24(T) exhibited the highest 16S rRNA gene sequence similarity values of 97.5 and 97.1 % to the type strains of Thalassobius maritimus and Thalassococcus halodurans, respectively. The neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain YCS-24(T) clustered with the type strain of T. halodurans. The DNA G+C content of strain YCS-24(T) was 58.0 mol% and its DNA-DNA relatedness values with T. halodurans JCM 13833(T) and T. maritimus GSW-M6(T) were 17 ± 6.2 and 23 ± 9.2 %, respectively. The predominant ubiquinone found in strain YCS-24(T) was Q-10 and the predominant fatty acid of strain YCS-24(T) was C(18:1) ω7c. The major polar lipids of strain YCS-24(T) were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, demonstrated that strain YCS-24(T) is distinguished from T. halodurans. On the basis of the data presented, strain YCS-24(T) (= KCTC 32084(T) = CCUG 62791(T)) represents a novel species of the genus Thalassococcus, for which the name Thalassococcus lentus sp. nov. is proposed.

Nanoscale mapping of Ag anode surface potential for high-performance T-organic light-emitting diode using kelvin probe force microscopy.

In this paper, the atmospheric pressure oxygen plasma was used to increase the work function of Ag thin films surface. But Ag thin films was generally not considered as an ideal bottom anode for T-OLED due to its rather low work function (approximately 4.2 eV). Using plasma treatment, the work function of Ag films was increased up to 4.84 eV at the plasma treatment time of between 60 and 90 s. The KPFM and Nano-indenter method analyzed and measured the work function of nano-distribution and nano-mechanical properties of Ag films surface. From the KPFM and Nano-indenter analysis, the stresses of Ag thin films were generated by induced oxygen radicals during the plasma treatment, and the work function of Ag thin film on nano-surface also changed by induce stress. It is can be explained that the nanosurface of thin-film would be generated the stress during the plasma treatment and the induced stress could change the surface property due to increase its volume. It is plausible that the induced stress was accelerated the production of AgO or AgO2 and excessive volume expansion of AgO2 could damage the surface.

Calprotectin in chronic rhinosinusitis eosinophil extracellular traps.

BACKGROUND: Calprotectin is an antimicrobial peptide primarily secreted by neutrophils. Furthermore, calprotectin secretion increases in patients with chronic rhinosinusitis (CRS) with polyps (CRSwNP) and positively correlates with neutrophil markers. However, CRSwNP is known to be associated with type 2 inflammation related to tissue eosinophilia. Therefore, the authors investigated calprotectin expression in eosinophils and eosinophil extracellular traps (EETs) and explored the associations between tissue calprotectin and the clinical findings of patients with CRS. METHODS: A total of 63 patients participated, and patients diagnosed with CRS were classified based on the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC) score. The authors performed hematoxylin and eosin staining, immunohistochemistry, immunofluorescence with calprotectin, myeloperoxidase (MPO), major basic protein (MBP), and citrullinated histone H3 with the participant's tissues. Finally, correlations between calprotectin and the clinical data were examined. RESULTS: Calprotectin-positive cells are co-localized not only in MPO-positive cells but also in MBP-positive cells in human tissues. Calprotectin was also involved in EETs and neutrophil extracellular traps. The number of calprotectin-positive cells in the tissue was positively correlated with the number of tissue and blood eosinophils. In addition, calprotectin in the tissue is associated with the olfactory function, Lund-Mackay computed tomography score, and JESREC score. CONCLUSIONS: Calprotectin, known to be secreted by neutrophils, in CRS was also expressed in eosinophils. In addition, calprotectin, which functions as an antimicrobial peptide, may play an important role in the innate immune response based on its EET involvement. Therefore, calprotectin expression could reflect as a disease severity biomarker for CRS.

Effects of Long-acting Injectable 3-Monthly Paliperidone Palmitate on the Clinical and Social Performance of Patients with Schizophrenia.

Objective: To investigate the effects of long-acting injectable 3-monthly paliperidone palmitate on the clinical and social functioning of patients with schizophrenia. Methods: This study enrolled patients with schizophrenia receiving long-acting injectable 1-monthly paliperidone palmitate for at least 4 months and who subsequently received 3-monthly paliperidone palmitate. Accordingly, 418 patients were followed up for 24 weeks. Their clinical symptoms and social functioning were measured using the Clinical Global Impression-Severity of Illness and Personal and Social Performance scales. Results: The Personal and Social Performance total score was significantly higher after 3-monthly paliperidone palmitate treatment than at baseline (baseline vs. week 24: 54.3 ± 18.0 vs. 61.0 ± 14.5 [mean ± standard deviation]; p < 0.001; Wilcoxon signed-rank test); the proportion of patients in the mildly ill group (scores 71-100) also increased significantly (baseline vs. week 24: 16.5% vs. 20.6%; p < 0.001; McNemar-Bowker test). The mean Clinical Global Impression-Severity of Illness score decreased significantly (baseline vs. week 24: 3.7 ± 1.0 vs. 3.4 ± 0.9; p < 0.001; Wilcoxon signed-rank test), as did the proportion of patients in the severely ill group (baseline vs. week 24: 4.1% vs. 2.1%; p < 0.001; McNemar-Bowker test). Conclusion: Continuous 3-monthly paliperidone palmitate treatment significantly enhances the personal and social performance of patients with schizophrenia and reduces the proportion of those with severe illness. These findings suggest that long-acting injectable antipsychotic administration at intervals longer than 1 month might improve the social functioning of and promote return to activities of daily living in patients with schizophrenia.

Household decision-making and the mental well-being of marriage-based immigrant women in South Korea.

OBJECTIVE: We assessed the association between household decision-making and mental well-being among Asian immigrant women residing in Korea. We also investigated if the impact varies by the regional origin and examined potential factors for joint decision-making. METHODS: We conducted a cross-sectional study using the Korean National Survey of Multicultural Families 2015 and logistic regression. We analyzed data from 11,188 married immigrant women ages 20 to 59 who were originally from East Asia or Southeast/South Asia and co-living with their spouses. We defined households as joint-decision, wife-decision, or husband-decision based on who decides how living expenses are spent. Mental well-being encompassed a depressive mood for two consecutive weeks, and life and marital satisfaction. RESULTS: After controlling for covariates, we showed that immigrant women in husband-decision households were more likely to have depressive mood (odds ratio [OR] 1.26, 95% confidence interval [CI]: 1.14-1.38), poorer life satisfaction (OR 1.49, 95% CI: 1.24-1.78), and poorer marital satisfaction (OR 1.81, 95% CI: 1.47-2.22) than women in joint-decision households. Immigrant women in wife-decision households had a similar but slightly lower odds of poor mental well-being. This association was less prominent for Southeast/South Asian origin than East Asian origin, while the age-adjusted prevalence rates of poor mental well-being among them were higher than their East Asian counterparts. Factors that restricted the odds of husband-decision did not necessarily guarantee wife-decision. CONCLUSIONS: This study suggests one-sided decision-making can be a risk factor for immigrant women's poor mental well-being, while joint decision-making is protective. Differences across regional origins suggest domestic decision-making might be a less important predictor for mental well-being in immigrants more occupied with adapting to the host society. Factors for joint decision-making should be addressed to improve the mental well-being of immigrant women.

The mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and the risk of suicidal ideation in Korean workers.

OBJECTIVES: This study aimed to investigate the mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and the risk of suicidal ideation in Korean workers. METHODS: Data from 33,047 workers were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys conducted in 2007-2018. Healthy workers without depressive disorders and chronic medical illnesses were included in the current study. Shift work patterns, sleep duration, working hours, depressive mood, and suicidal ideation were assessed using self-reported questionnaires. Multivariate logistic regressions were used to examine the association between shift work and the risk of suicidal ideation. Additionally, mediating studies were conducted to identify the roles of working hours and sleep durations on the association. RESULTS: Compared with daytime workers, shift workers had 1.33 times greater risk of suicidal ideation (OR = 1.33, 95% Cl = 1.17-1.52, p < 0.001). Specifically, among shift work patterns, fixed-night shift, 24-h rotating shift and irregular rotating shift were associated with the risk of suicidal ideation when compared with daytime workers (irregular rotating shift: OR = 1.92, 95% Cl = 1.29-2.86, p = 0.001; fixed-night shift: OR = 1.75, 95% Cl = 1.32-2.31, p < 0.001; 24-h rotating shift: OR = 1.58, 95% Cl = 1.06-2.36, p = 0.024). In the mediating study, working hours, sleep duration and depressive mood significantly mediated the relationship between shift work and suicidal ideation (direct effect: ß = 0.019, p = 0.001; indirect effect: ß = 0.004, p = 0.031; total effect: ß = 0.023, p < 0.001). CONCLUSION: This study revealed that shift workers had a greater risk of suicidal ideation. The patterns significantly associated with suicidal ideation were irregular rotating, fixed-night, and 24-h rotating shifts. The pathway analysis revealed serial mediating effects of working hours, sleep duration, and depressive mood on the association between shift work and suicidal ideation.

Excess suicide attributable to the COVID-19 pandemic and social disparities in South Korea.

The impact of COVID-19 pandemic on suicide remains unclear and might differ according to individuals' socioeconomic characteristics. We aimed to investigate excess suicide attributable to COVID-19 in South Korea, stratified by the outbreak period and individual characteristics. We obtained daily time-series suicide mortality data for January 2017-December 2020 from the Korea National Statistics Office and performed a two-stage interrupted time-series analysis. We estimated excess suicide in 16 regions of Korea using a quasi-Poisson time-series regression model and pooled the region-specific estimates using a mixed-effects multivariate meta-analysis model in the first and second stages, respectively. From February 18 to December 31, 2020, suicide decreased by 9.5% [95% empirical confidence interval (eCI): 3.8%, 15.6%] compared to the number expected from the pre-pandemic period. The decrease in excess suicide risk from the initial pandemic was pronounced during the pandemic's first and third waves. Further, we found that the decrease in suicide was more evident in individuals who were male [11.7% (95% eCI: 5.5%, 18.0%)], middle-aged [13.7% (95% eCI: 7.8%, 19.6%)], highly educated [12.6% (95% eCI: 6.4%, 19.4%)], and married [13.6% (95% eCI: 8.0%, 20.3%)] than in the general population, based on the point estimates. Our results provide timely evidence to establish public health policies for suicide prevention and suggest the prioritization of resource allocation for mental health of individuals based on individual characteristics.

The effects of smoking habit change on the risk of depression-Analysis of data from the Korean National Health Insurance Service.

BACKGROUND: We examined the effects of smoking habit change on the risk of depression using the National Health Insurance Service-National Health Screening Cohort database of Korea. METHODS: This nationwide population-based cohort study included 88,931 men aged 40 years or older. The participants were divided into baseline heavy (≥20 cigarettes/day), moderate (10-19 cigarettes/day), and light (<10 cigarettes/day) smokers, quitters, and never smokers. Smokers were then categorized as continual smokers, reducers, quitters, and non-smokers based on the two-year change in smoking status between the first and second health examinations. The participants were followed from the index date to 2013 to assess depression status. Cox proportional models were used to examine the effects of smoking habit change on the risk of depression. RESULTS: After a median 7.7 years of follow-up, 2,833 depression cases were identified. Never smokers and long-term quitters had a lower risk of depression than heavy continual smokers (hazard ratio, HR 0.817; 95% CI, confidence interval 0.689-0.967 and HR: 0.691; 95% CI: 0.559-0.853, respectively). Short-term quitters and reducers had a lower risk of depression, but it was not significant. The influence of smoking on depression was prominent among men in their 50 s (HR: 0.585; 95% CI: 0.419-0.820 in long-term quitters, HR:.0.738; 95% CI: 0.570-0.954 in never smokers). LIMITATIONS: The information about smoking habits was based on self-reported questionnaires. This study examined only men because the smoking rate among women in Korea is very low. CONCLUSIONS: This population-based study found that never smokers and long-term quitters have lower risk of depression. The risk of depression decreased when the amount of smoking decreased, but the difference was not statistically significant. Furthermore, more attention should be paid to middle-aged men when formulating smoking cessation policies.

Difference in spectral power density of sleep electroencephalography between individuals without insomnia and frequent hypnotic users with insomnia complaints.

Previous spectral analysis studies on insomnia have shown inconsistent results due to their heterogeneity and small sample sizes. We compared the difference of electroencephalogram (EEG) spectral power during sleep among participants without insomnia, insomniacs with no hypnotic use, hypnotic users with no insomnia complaints, and hypnotic users with insomnia complaints using the Sleep Heart Health Study data, which is large sample size and has good quality control. The fast Fourier transformation was used to calculate the EEG power spectrum for total sleep duration within contiguous 30-s epochs of sleep. For 1985 participants, EEG spectral power was compared among the groups while adjusting for potential confounding factors that could affect sleep EEG. The power spectra during total sleep differed significantly among the groups in all frequency bands (pcorr < 0.001). We found that quantitative EEG spectral power in the beta and sigma bands of total sleep differed (pcorr < 0.001) between participants without insomnia and hypnotic users with insomnia complaints after controlling for potential confounders. The higher beta and sigma power were found in the hypnotic users with insomnia complaints than in the non-insomnia participants. This study suggests differences in the microstructures of polysomnography-derived sleep EEG between the two groups.