Chang-Gyu Park

Park S, et al. J Korean Med Sci. 2026 Mar;41:e85. https://doi.org/10.3346/jkms.2026.41.e85

Background: Patients with heart failure (HF) experience a marked reduction in overall skeletal muscle strength and exercise capacity, which is detrimental to their prognosis. This study examined the clinical implications of handgrip strength (HGS) in patients with HF. Methods: Overall, 173 patients (mean age, 62 years; 81.5% male) underwent cardiac rehabilitation from 2015 to 2020. Baseline HGS was measured as the average value (kg) for both hands using a handheld dynamometer. For each patient, distance walked during a 6-min walk test and metabolic equivalents were recorded. The primary outcome was the composite of readmissions for HF and all-cause death. Results: Receiver operating characteristic curve for the primary outcome revealed 24.9 kg as the HGS cutoff point (area under curve: 0.702, 95% confidence interval [0.610, 0.794], p < .001) and multivariable Cox proportional hazard analysis revealed that lower HGS was significantly associated with a higher risk of readmission for HF or all-cause death (hazard ratio [HR] 6.44, 95% confidence interval [2.86, 14.50], p < .001). This result is mainly attributed to the increased risk of readmission for HF in this group (hazard ratio 6.75, 95% confidence interval [2.87, 15.88], p < .001). Moreover, HGS was significantly positively correlated with distance on 6-min walk test (r = .564, p < .001) and metabolic equivalents (r = .419, p < .001), and is one of the strongest predictors of each exercise capacity category. Conclusions: As our findings suggested, HGS is an indicator of exercise capacity and a useful marker for predicting hospital readmission or all-cause death in patients with HF.

A significant crop pest, Mythimna loreyi, migrates annually to Korea and has been frequently observed in rice and corn fields. However, the phenology of this pest, particularly in relation to its ecological interactions and host crop seasons in Korea, remains poorly understood. This study aims to clarify the timing of the second generation of M. loreyi in Korea to enhance pest management strategies. To achieve this, we developed temperature-dependent models for developmental and ovipositional rates, studying these processes across five constant temperatures (15, 20, 25, 30, and 35°C). Our models, which showed a high correlation with observed data (r² ≥ 0.93), include a theoretical approach that combines the developmental variation of immatures with the necessary degree-days for 50% egg laying and complete egg development. These predictions allow for the forecasting of the second generation’s occurrence, with relatively small deviations (one to three days) observed at two different field sites. The insights from this study are critical for both understanding the ecology of M. loreyi and for informing practical management decisions, such as optimal placement of barriers to prevent immigration and strategies for controlling local populations.

An invasive species, Pochazia shantungensis (Hemiptera: Ricaniidae), causes serious economic damage to fruit trees. In Korea, this pest is mainly managed using chemical insecticides. However, the management timing and insecticides for P. shantungensis negatively affect honeybee populations. Thus, this study estimated the decision-making level for P. shantungensis in persimmons to decrease insecticide application and increase management efficiency. We determined which developmental stage (i.e., egg, nymph, and adult) affected the damage-related factors (numbers of new shoots and fruit formations, and harvest amount) of persimmons using both spatial analyses and linear relationships. The distribution of P. shantungensis eggs was spatially correlated with the one of persimmon fruit number. However, we did not find any linear relationships between the densities of P. shantungensis eggs and damage-related factors of persimmons. Instead, we found that the density of P. shantungensis correlated with the death of oviposited branches. From the developed model of branch death possibility based on egg mass density, 5.75 egg masses per newly developed branch were proposed as the decision-making level. The findings would help increase the efficiency of P. shantungensis management in persimmon orchards and develop decision-making levels for other insects.

Park S, et al. Korean Circ J. 2024 Apr;54:e42. https://doi.org/10.4070/kcj.2024.0023

Park S, et al. J Korean Med Sci. 2023 May;38(23):e179. https://doi.org/10.3346/jkms.2023.38.e179

Even though the optimum sampling methods for invasive pests are very important in newly invaded areas, the standard sampling unit of Ricania shantungensis is still undeveloped in persimmons. Among all developmental stages of R. shantungensis, the egg has close relationship between its density and subsequent tree damage. Thus, this study was conducted to suggest an optimum sampling unit for R. shantungensis eggs in persimmons based on characteristics of its within-tree distribution pattern. The within-tree distribution pattern was characterized with 60 persimmon trees by cutting 12 branches at three vertical levels (low, middle, and high) in four horizontal criteria (east, west, south, and north) per tree. The sampling units were determined based on coefficient of variation (CV) and coefficient of determination (r²) calculated from egg mass numbers per 10 cm from the tip within a branch. In numbers of R. shantungensis egg masses, there was no significant difference (P > 0.05) horizontally, but significant (P < 0.05) difference vertically. More R. shantungensis eggs were found on terminal branches of each trunk. The 60 cm from the tip of branches in the terminal positions of each trunk was selected as the optimum sampling unit for R. shantungensis in persimmons because this unit has the lowest CV value and more than 0.9 of r² value. Even though the optimum sample number per tree should be determined field-specifically, it would be acceptable to sample two or three branches by considering this pests’ recognizable damage level. This small sampling unit could make the sampling of R. shantungensis become more economical, precise, and consistent in persimmon fields.

Riptortus pedestris (Fabricius) has caused severe agricultural damage in Asian regions. To clarify genetic relationships among different populations of R. pedestris in Korea, 294 COI sequences were generated from 294 individual samples collected in 42 local regions. In total, 36 haplotypes were detected from the 294 COI sequences, and the genetic distances among the 42 local populations ranged from 0.00 % to 1.50 %. In the AMOVA results, a variability of more than 98 % was observed within populations, and the median joining (MJ) networks revealed that R. pedestris has expanded by crossing the nine geographical groups. Most of the samples shared one haplotype, H2; however, some samples obtained from the same regions displayed slight genetic differences. These results indicate that R. pedestris have undergone a series of genetic variations.

Metcalfa pruinosa (Say, 1830) (Hemiptera: Flatidae) has caused substantial agricultural damage since its recent introduction to the Republic of Korea; however, the source of this introduction is still unclear. To examine the genetic divergence and phylogenetic relationships among several populations of M. pruinosa from Korea and foreign countries, 251 COI sequences from 251 samples collected from Korea, France, Italy, Spain, Slovenia, and the United States were newly analyzed, together with seven published COI sequences from Canada. In total, 19 haplotypes were detected from the 258 COI sequences, and three haplotypes, H1, H3, and H9, were detected from samples in Korea. The MJ network and Bayesian inference revealed that the three haplotypes of Korea were closely connected with samples of Italy, Spain, Slovenia, France, and the United States. Our study revealed the possibility of multiple invasions of M. pruinosa from Europe and/or North America into Korea.