Impact of Korean Military Service on the Prevalence of Steatotic Liver Disease: A Longitudinal Study of Pre-enlistment and In-Service Health Check-Ups.

Background/Aims: Young Korean men are obligated to serve in the military for 18 to 21 months. We investigated the effects of military service on steatotic liver disease (SLD) and other metabolic parameters. Methods: Pre-enlistment health check-up performed from 2019 to 2022 and in-service health check-up performed from 2020 to 2022 were merged as paired data. SLD was defined as a hepatic steatosis index of 36 or higher. Hypertension (HTN) and hypertriglyceridemia were also included in the analysis. Results: A total of 503,136 paired cases were included in the analysis. Comparing pre-enlistment and in-service health check-ups, the prevalence of SLD (22.2% vs 17.6%, p<0.001), HTN (7.6% vs 4.3%, p<0.001), and hypertriglyceridemia (8.1% vs 2.9%, p<0.001) decreased during military service. In terms of body mass index, the proportion of underweight (8.2% vs 1.4%, p<0.001) and severely obese (6.1% vs 4.9%, p<0.001) individuals decreased over time. Regarding factors associated with SLD development and resolution, age was positively associated with SLD development (odds ratio, 1.146; p<0.001) and a health check-up interval of <450 days was a protective factor for SLD development (odds ratio, 0.746; p<0.001). Those serving in the marines were less likely to develop SLD, whereas those serving in the navy were more likely to develop SLD. Serving in the army or the navy was negatively associated with SLD resolution, whereas serving in the air force was positively associated with SLD resolution. Conclusions: The prevalence of SLD, HTN, and hypertriglyceridemia decreased substantially during Korean military service.

Current Status of Cold Injuries in the South Korean Military Over the Past 5 Years: Analysis and Assessment Based on the 2023-2024 Surveillance System.

INTRODUCTION: This study aimed to examine the prevalence of cold injuries and review the cold injury monitoring system in the South Korean military. MATERIALS AND METHODS: This study conducted a retrospective and cross-sectional analysis using data from the Defense Medical Statistic Information System (DMSIS) on cold injuries among military personnel from 2018 to 2023. It incorporated findings from the Korean Armed Forces Medical Command's cold injury surveillance system and analyzed cases from the Armed Forces Capital Hospital, covering all branches of the military by status and rank. RESULTS: An analysis of cold injury in the South Korean military over the past 5 years revealed varying numbers of cases treated, from 799 in 2018-2019 to 467 in 2022-2023. According to the surveillance system in 2023-2024, the Army experienced the majority of these cases, with 94.5% of the total. The incidence per 1,000 personnel was the highest in the Army at 0.98 compared to the Air Force and Navy/Marine Corps. Rank-based analysis indicated the most affected were private first-class soldiers. Frostbite was the most frequent condition, alongside chilblains, hypothermia, and immersion injuries, with no marked difference in the type of illness across branches. CONCLUSIONS: The study underscores the need for focused prevention and treatment, particularly in the Army. By analyzing data from a newly implemented surveillance system, it revealed a higher incidence of frostbite and chilblains among lower ranks. The findings highlight the importance of targeted educational measures and enhanced response strategies to protect personnel against cold injuries.

Analyzing and Assessing the Current Status of Heat-Related Illnesses in the South Korean Military.

INTRODUCTION: The population of the Republic of Korea often experiences heat-related illnesses during summer that are exacerbated by significant variations. With rising temperatures attributed to global warming and other environmental changes within the military, combined with the military medical services' mission to uphold combat capabilities and promote health, it has become crucial to accurately understand the status of heat-related illnesses and integrate more comprehensive and systematic preventive measures. This study aimed to analyze data on heat-related illnesses between 2018 and 2022 to assess and reflect on the said diseases in the South Korean Military. MATERIALS AND METHODS: We performed a secondary analysis using data provided by the Defense Medical Statistic Information System. This single-institution retrospective, cross-sectional study was approved by the Institutional Review Board of the Armed Forces Medical Command (approval number: AFMC-2023-11-001). RESULTS: Over the past 5 years, the annual number of soldiers treated for heat-related illnesses, whether as outpatients or inpatients, at division medical facilities and military hospitals ranged from 846 to 1,250 cases per year. The proportion of severe cases fluctuates annually between 1.1% and 1.8%. Notably, 94 to 96% of all heat-related illnesses were recorded between May and September, with peak rates in July and August. CONCLUSION: The army reported the highest number of heat-related illnesses among military branches, with soldiers comprising the majority of cases. This highlights the urgent need for enhanced heat illness prevention measures within army ranks. Notably, the incidence of these illnesses peaked during July and August, underlining the critical periods for intensified preventive efforts.

Erratum: Stable isotope analysis of Joseon people skeletons from the cemeteries of Old Seoul City, the capital of Joseon Dynasty.

[This corrects the article on p. 244 in vol. 47, PMID: 25548722.].

Stable isotope analysis of Joseon people skeletons from the cemeteries of Old Seoul City, the capital of Joseon Dynasty.

Stable carbon and nitrogen isotope analysis reveals the diets of different human populations in history. In this study, we performed stable isotope analysis on human skeletons from Joseon-period cemeteries discovered around Old Seoul City (Hansung). Our data clearly showed that Joseon individuals consumed more C3-based than C4-based foods as the main staples, and that the proteins they ate were mainly of terrestrial, but not of marine origin. Stable isotope values exhibited unique patterns in each of our sample subgroups. Whereas the δ(13)C values did not show any statistical differences among the subgroups, significantly higher values of δ(15)N were found in males than in females, which might reflect dietary differences between the sexes. For a fuller understanding of the dietary patterns of pre-industrial (pre-20th century) Koreans, additional studies on Joseon samples from Korean archaeological sites will be necessary.

Effects of the type of solvents on the morphology of styrene-methacrylic acid random copolymers cast onto silicon wafer.

The effects of the type of solvents on the aggregation behavior of poly(styrene-ran-methacrylic acid) (PSMAA) cast onto silicon wafer were studied using a SEM method. It was found that polystyrene prepared from DMF formed non-spherical aggregates but that PSMAA formed mixtures of ellipsoids and spheres. As the acid content increased, the spheres having a distinct boundary started contacting each other, and the average size of spherical particles decreased. Upon neutralization, the spherical particles became contacted spheres covered with much smaller spheres (ca. 20 nm in their sizes) and formed micro-gels. These results were compared to the data in the previous study of samples obtained from either water or THF. It was observed that the solubility parameters of the copolymers and ionomers, and polarity of solvents were some of key factors that determine the aggregation behavior of the polymers. The volatility of the solvent was also found to be an important factor for the aggregation behavior of polymers.

Effects of the neutralization degree on morphologies in "drying-mediated" samples of sodium neutralized poly(styrene-ran-methacrylic acid) copolymers in THF.

To understand the effect of neutralization degree on surface morphologies of drying-mediated samples, un-neutralized, partially and fully Na-neutralized poly(styrene-ran-methacrylic acid) (PSMAA) prepared from THF solutions were investigated using a scanning electron microscope (SEM). We varied the content of acid groups as well as the degree of neutralization of the PSMAA copolymers. The neutralization degree changed the surface morphologies of the polymers significantly. When the acid group content was low (<9.4 mol%), the morphologies of PSMAA were found to be very similar to that of homo-PS, forming a continuous matrix with a number of circular pores. Upon neutralization, the shape of the pores changed to non-circular form and the porous matrix was mingled with the congregated aggregates. With increasing neutralization degrees, the boundary between porous films and deformed sphere-shaped aggregates became unclear. For fully neutralized forms, only highly porous layered films were formed, indicating micro phase separation between solvent and aggregated copolymer networks.

Effects of molecular weights of sulfonated polystyrene ionomers on the formation of stable colloidal particles in tetrahydrofuran/water (1/99) mixture.

The effects of the molecular weights (MWs) of sulfonated polystyrene copolymers on the colloidal particle sizes and the size distributions were investigated. It was found that the size of colloidal particle of acid copolymer of relatively low MW, being largest in comparison with higher MW sample, decreased strongly and then remained constant at ca. 11 nm upon dilution. These findings implied that at relatively high concentrations the colloids aggregated together due to the interactions between particles having relatively non-polar surface and that the colloids might contain more than one polymer chain. In the cases of copolymers of high MWs, the colloid sizes did not change much with the solution concentration, but the particle size of the higher MW copolymer was slightly larger than that of the lower MW sample. This was understood; the higher MW copolymer, the longer polymer chain, and the larger colloid. The size of the ionomeric colloids was found to increase slightly upon dilution, which was due to the repulsion of ionic groups on the surface. As expected, the size of the particles of the ionomers showed a similar trend found in the acid samples.

Formation of the colloidal particles of sulfonated polystyrene ionomers neutralized with either Na(I) or Ba(II) in ThF/water (1/99) mixture.

The sizes of colloidal particles in THF/water (1/99 v/v) of the sulfonated polystyrene copolymers containing 2.1, 5.1 and 9.4 mol% of either acidic or ionic repeat units were determined using a dynamic light scattering technique. It was observed that for the acid copolymer containing 2.1 mol% of acidic units the size of the particle and size distribution decreased significantly as the solution concentration decreased from 2.0 x 10(-4) to 5.0 x 10(-6) g/mL. However, when the content of acidic units increased to 5.1 and 9.4 mol%, the size of the particles and size distribution increased slightly with decreasing solution concentrations. It was also found that the neutralization of the acid group with Na(I) induced the slow increase in the diameter of colloidal particles of the ionomers with decreasing solution concentration, and that the size of the colloids decreased with increasing ion contents. Thus, it was suggested that the former and latter findings could be understood using the polyelectrolyte effect and charge density concepts, respectively. For the ionomers neutralized with Ba(II), it was found that the size of the single colloidal particles was similar to that of the Na(I) ionomer. However, the aggregates of the colloids were not easily separated by the ultrasonication. Thus, it was speculated that the Ba(II) cations placed inside the aggregates of hydrophobic environment acted as the links between colloidal particles.

Aggregation behavior of Na-neutralized styrene-ran-methacrylic acid copolymers in aqueous solution.

The aggregation behavior of un-neutralized, partly and fully Na-neutralized poly(styrene-ran-methacrylic acid) copolymers in aqueous solution was investigated using a SEM technique. It was observed that the un-neutralized copolymer formed spherical particles on the Si wafer, and the average size of particles was ca. 160 nm. The particle sizes did not change much with acid content. Upon the neutralization of the acid groups of the copolymer with NaOH, the copolymer became more hydrophilic, leading to the formation of network-like feature consisting of much smaller particles (< 50 nm), compared to those of the acid copolymers. With increasing ionization, the boundary of the particles forming networks faded away, implying the formation of tubular structures.

Effect of the charge on the morphology of sodium salt form of the randomly sulfonated polystyrene ionomer cast onto silicon wafers.

The morphology of the sodium salt form of randomly copolymerized polystyrene sulfonate (Na-PSS) in water/THF(99/1 v/v) cast onto silicon wafers, was studied by using scanning electron microscope (SEM). The contents of the sulfonate repeat units in Na-PSS were 1.1, 2.4, 4.6, 10.8, and 15.6 mol%. Based on the observed SEM images, the morphology of the Na-PSS changed with increasing ionic group content. For 1.1 and 2.4 mol%, sphere-shaped aggregates were formed with average sizes of 90 nm and of 77 nm, respectively. For 4.6 mol% and 10.8 mol%, 20-30 nm-sized aggregates were close-packed and fused together, resulting a surface with large roughness and ca. 10 nm-sized pores were formed. As the mol% increased to 15.6, the surface became smoother and flat films were formed.