Regional differences in the effects of healthy aging on depressive symptoms: a Korean longitudinal study of aging (2006-2020)

Background

Depression is a widely prevalent, often recurrent condition. To analyze the regional differences in depressive symptoms over time, we investigated urban-rural differences in change in depression over time in South Korea and the association between healthy aging and depressive symptoms among middle-aged and older adults.

Methods

Data collected in the Korean Longitudinal Study of Aging, from 2006 to 2020, of adult participants aged ≥45 years without depressive symptoms were analyzed. Healthy aging was defined under five principal components: absence of chronic disease, good physical function, normal cognitive function, active social engagement, and good psychological adaptation. Depressive symptoms were measured using the short version of the Center for Epidemiologic Studies Depression Scale. Using the Andersen-Gill model for recurrent time-to-event, we examined the effect of healthy aging on depressive symptoms, with a subgroup analysis based on the residential area.

Results

Of the 7,708 participants, 78.2% lived in urban areas and 39.4% achieved healthy aging. In 2008, rural residents had a higher incidence of depressive symptoms (rural 11.8%; urban 8.9%); however, after 2016, the depressive symptoms of urban residents gradually increased (rural 6.4%; urban 12.1%). Unhealthy aging (adjusted hazard ratio = 3.04, 95% confidence interval: 2.72-3.39) and urban residence (adjusted hazard ratio = 1.15, 95% confidence interval: 1.06-1.24) were risk factors for depressive symptoms. The subgroup analysis revealed that individuals who did not achieve healthy aging had an increased risk of depressive symptoms, regardless of their residential area (hazard ratio [95% confidence interval]: urban, 3.13 [2.75-3.55]; rural 2.59 [2.05-3.28]).

Conclusion

As urbanization accelerates, urban residents have a higher risk of depressive symptoms than rural residents. Healthy aging is an essential factor in reducing depressive symptoms. To achieve healthy aging, appropriate interventions and policies that target the middle-aged adults and gradually extend to older adults are needed, considering individual and regional factors.

Analysis of Effect of Intensity of Aerobic Exercise on Cognitive and Motor Functions and Neurotrophic Factor Expression Patterns in an Alzheimer's Disease Rat Model

The effect of aerobic exercise at different intensities on Alzheimer's disease (AD) still remains unclear. We investigated the effect of aerobic exercise at different intensities on cognitive and motor functions and neurotrophic factor expression. Thirty-two AD-induced rats were randomly assigned to control (CG), low-intensity (Group I), medium-intensity (Group II), and high-intensity (Group III) exercise groups. Each group, except for the CG, performed aerobic exercise for 20 min a day five times a week. After performing aerobic exercise for 4 weeks, their cognitive and motor functions and neurotrophic factor expression patterns were analyzed and compared between the groups. All variables of cognitive and motor functions and neurotrophic factor expression were significantly improved in Groups I, II, and III compared to those in the CG (p < 0.05). Among the neurotrophic factors, brain-derived neurotrophic factor (BDNF) expression was significantly improved in Group III compared to that in Groups I and II (p < 0.05). In the intra-group comparison of cognitive and motor functions, no significant difference was observed in CG, but the aerobic exercise groups showed improvements. Only Group III showed a significant improvement in the time it took to find eight food items accurately (p < 0.05). Aerobic exercise improved the cognitive and motor functions and neurotrophic factor expression patterns in the AD-induced rat model, with high-intensity aerobic exercise having greater effects on cognitive function and BDNF expression.

Effects of Omega-3 Fatty Acid Supplementation on Skeletal Muscle Mass and Strength in Adults: A Systematic Review

Previous studies have suggested that omega-3 polyunsaturated fatty acids, predominantly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have several health benefits. However, their effect on changes in skeletal muscle mass and strength has not been established, owing to differences in study designs. This systematic review aimed to investigate the recent evidence regarding the role of dietary EPA and DHA in muscle mass changes and their association with muscle strength. Databases including PubMed and Google Scholar were searched for randomized controlled trials and single-arm interventions that investigated the effects of omega-3 fatty acids on skeletal muscle mass, strength, and body composition in adults aged 18 years and older. A total of 18,521 studies were retrieved from the databases and manual searches; 21 studies were quality assessed, and the findings were summarized. Studies were categorized into 3 main categories according to the type of omega-3 fatty acid supplementation: pure compounds such as oil tablets, formulated forms with protein, leucine, and vitamin D, and ingredients added to enteral nutrition support products. Overall, the majority of the study results appeared to indicate that omega-3 fatty acids are beneficial for muscle health. However, meta-analysis was not conducted because of the heterogeneity of the study participants, evaluation method of muscle indices, and intervention periods among the studies. High-quality studies are required to validate our conclusions. However, this systematic review of the effects of EPA and DHA on skeletal muscle and body composition provides evidence that can be applied in both clinical and industrial settings.

Unraveling the roles of aromatic cluster side-chain interactions on the structural stability and functional significance of psychrophilic Sphingomonas sp. glutaredoxin 3

This study investigates the impact of aromatic cluster side-chain interactions in Grx3 (SpGrx3) from the psychrophilic Arctic bacterium Sphingomonas sp. Grx3 is a class I oxidoreductase with a unique parallel arrangement of aromatic residues in its aromatic cluster, unlike the tetrahedral geometry observed in Trxs. Hydrophilic-to-hydrophobic substitutions were made in the aromatic cluster, in β1 (E5V and Y7F), adjacent β2 (Y32F and Y32L), both β1 and β2 (E5V/Y32L), and short α2 (R47F). The hydrophobic substitutions, particularly those at or near Tyr7 (E5V, Y7F, Y32F, and R47F), increased melting temperatures and conformational stability, whereas disrupting β1-β2 interactions (Y32L and E5V/Y32L) led to structural instability of SpGrx3. However, excessive hydrophobic interactions (Y7F and E5V/Y32L) caused protein aggregation at elevated temperatures. All mutations resulted in a reduction in α-helical content and an increase in β-strand content. The R47F mutant, which formed dimers and exhibited the highest β-strand content, showed increased conformational flexibility and a significant decrease in catalytic rate due to the disturbance of β1-α2 interactions. In summary, the configuration of the aromatic cluster, especially Tyr7 in the buried β1 and Arg47 in the short α2, played crucial roles in maintaining the active conformation of SpGrx3 and preventing its protein aggregation. These modifications, reducing hydrophobicity in the central β-sheet, distinguish Grx3 from other Trx-fold proteins, highlighting evolutionary divergence within the Trx-fold superfamily and its functional versatility.

Sleep-related problems as a mediator in the association between depression and work-family conflict in middle-aged female workers: A population-based study

AIM

To investigate the mediating effect of sleep-related problems on the relationship between depression and work-family conflicts (WFCs) among middle-aged female workers.

DESIGN

Secondary analysis of cross-sectional study.

METHODS

Overall, 15,718 female workers aged 40-65 years from the Sixth Korean Working Conditions Survey (KWCS) were included. Depression was assessed using the WHO-5 wellbeing index; sleep-related problems and WFCs were measured with five items on a Likert scale. The mediating effect of sleep-related problems between depression and WFCs was analysed using model 4 of Hayes PROCESS macro for SPSS.

RESULTS

There was a significant positive correlation between depression and both sleep-related problems (r = 0.225, p < 0.001) and WFCs (r = 0.124, p < 0.001). Depression also had a significant effect on sleep-related problems (β = 0.221, p < 0.001) and WFCs (β=0.061, p < 0.001). Sleep-related problems had a significant effect on WFCs (β = 0.282, p < 0.001). The indirect effect of depression on WFCs by mediating sleep-related problems was β = 0.062 (95% bootstrap confidence interval = 0.057-0.068). The study also confirmed the significance of the mediating effect of sleep-related problems in the relationship between depression and WFCs.

Essential roles of buried phenylalanine in the structural stability of thioredoxin from a psychrophilic Arctic bacterium Sphingomonas sp

Thioredoxin (Trx), a small redox protein, exhibits thermal stability at high temperatures regardless of its origin, including psychrophiles. Trxs have a common structure consisting of the central β-sheet flanked by an aliphatic cluster on one side and an aromatic cluster on the other side. Although the roles of aromatic amino acids in the folding and stability of proteins have been studied extensively, the contributions of aromatic residues to the stability and function of Trx, particularly Trxs from cold-adapted organisms, have not been fully elucidated. This study examined the roles of aromatic amino acids in the aromatic cluster of a Trx from the psychrophilic Arctic bacterium Sphingomonas sp. PAMC 26621 (SpTrx). The aromatic cluster of SpTrx was comprised of W11, F26, F69, and F80, in which F26 at the β2 terminus was buried inside. The substitution of tyrosine for F26 changed the SpTrx conformation substantially compared to that of F69 and F80. Further biochemical and spectroscopic investigations on F26 showed that the F26Y, F26W, and F26A mutants resulted in structural instability of SpTrx in both urea- and temperature-induced unfolding and lower insulin reduction activities. The Trx reductase (SpTR) showed lower catalytic efficiencies against F26 mutants compared to the wild-type SpTrx. These results suggest that buried F26 is essential for maintaining the active-site conformation of SpTrx as an oxidoreductase and its structural stability for interactions with SpTR at colder temperatures.

Concealment and Disclosure: The Cholera Crisis of 1969-70 in Korea

The anti-cholera measures of 1969-70 represent one of the most unsuccessful quarantine cases in modern Korea. The military government, which overthrew the democratic government in 1961, tried to amend the Constitution aiming for a long-term seizure of power, and had to overcome the cholera crisis of 1969-70. Previous scholarship has emphasized the limitation of the state power when it came to controlling the cholera epidemic or the poor sanitation system of 1969-70. However, it is undeniable that the military government did have organizations, facilities, and human capital available. When a cholera epidemic broke out in 1963-64, the military government defended its people against cholera as part of the Revolutionary Tasks. Furthermore, it took counsel from a team of medical professionals knowledgeable in microbiology. In 1969, the possibility of bacteriological warfare by North Korea emerged while the government responded to cholera. To avoid this crisis, Park Chŏng-hŭi's military government, which had been preparing for longterm rule, had to provide successful model in the cholera defense. For the military government, the concealment and distortion of infectious disease information was inevitable. Many other medical professionals trusted the activities of international organizations more than they did the government bodies, and the media accused the government of fabricating cholera death statistics. As the government failed to prevent the cholera crisis, it tightened its secrecy by concealing facts and controlling information.

The Effect of Virtual Reality Exercise Program on Sitting Balance Ability of Spinal Cord Injury Patients

(1) Background: Virtual reality (VR) is a useful device for rehabilitation therapy. The purpose of this study was to examine the effect of virtual reality exercise program on sitting balance with spinal cord injury; (2) Methods: 20 subjects who selected on the basis of the screening criteria were divided into the experimental group (n = 10) who underwent the virtual reality exercise program and rehabilitation therapy and the control group (n = 10) who underwent a regular sitting balance training program and a regular rehabilitation therapy. Each intervention consisted of a 30-min session a day, three times a week, for eight weeks. In order to measure functions of the sitting balance, FSA (force sensitive application) and LOS (limit of stability) were used before and after the treatment intervention; (3) Results: We found significant differences for the FSA, LOS between pre-test and post-test in the 2 groups; (4) Conclusions: The findings of this study suggest that virtual reality exercise program can be applied as a useful approach for spinal cord injury patients.

Cloning, Expression, and Characterization of a Psychrophilic Glucose 6-Phosphate Dehydrogenase from Sphingomonas sp. PAMC 26621

Glucose 6-phosphate dehydrogenase (G6PD) (EC 1.1.1.363) is a crucial regulatory enzyme in the oxidative pentose phosphate pathway that provides reductive potential in the form of NADPH, as well as carbon skeletons for the synthesis of macromolecules. In this study, we report the cloning, expression, and characterization of G6PD (SpG6PD1) from a lichen-associated psychrophilic bacterium Sphingomonas sp. PAMC 26621. SpG6PD1 was expressed in Escherichia coli as a soluble protein, having optimum activity at pH 7.5⁻8.5 and 30 °C for NADP⁺ and 20 °C for NAD⁺. SpG6PD1 utilized both NADP⁺ and NAD⁺, with the preferential utilization of NADP⁺. A high Km value for glucose 6-phosphate and low activation enthalpy (ΔH‡) compared with the values of mesophilic counterparts indicate the psychrophilic nature of SpG6PD1. Despite the secondary structure of SpG6PD1 being maintained between 4⁻40 °C, its activity and tertiary structure were better preserved between 4⁻20 °C. The results of this study indicate that the SpG6PD1 that has a flexible structure is most suited to a psychrophilic bacterium that is adapted to a permanently cold habitat.

Secondary Traumatic Stress and Burnout of North Korean Refugees Service Providers

OBJECTIVE

The current study investigated the burnout and secondary traumatic stress of service providers for North Korean (NK) refugees based on the conceptual framework of theJob Demands-Resources (JD-R) model of workplace burnout.

METHODS

A cross-sectional self-administered survey was conducted with a national sample consisting of all 63 organizations in direct services to North Korean refugees. Of the estimated total number of 230 service providers comprising of social workers, psychotherapists, job counselors and paraprofessional counselors, 179 completed the survey, a 77.8% return rate.

RESULTS

While job resources such as personal commitment to work and organizational support indicated inverse relations to burnout, job demands such as workload, work environment and secondary traumatic stress (STS) showed a positive relationship to worker burnout. The STS were present in more than half of the respondents (51.3%), of which 20.7% of them indicating a severe level of STS. The STS proved to be the most significant risk to worker burnout as it showed strong relations to all three dimensions of burnout.

CONCLUSION

Structural issues of chronic work overload and poor work environment need to be addressed to reduce staff burnout. STS is a serious occupational hazard in working with North Korean refugees.