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Diatoms, a type of microalgae distributed worldwide, have been identified as potential sources of biomass, lipids, and high-value compounds. While marine diatoms have been extensively studied, the potential of freshwater diatoms still needs to be explored. In this study, a novel strain of freshwater diatom was isolated from the Jungnangcheon stream located in Seoul, Republic of Korea (37°33'08.0" N, 127°02'40.0" E). This newly isolated strain was classified through phylogenetic analysis, and its morphology was investigated using light and electron microscopy; it was named Nitzschia palea HY1. N. palea HY1 grown in freshwater media (FDM) produced higher biomass (0.68 g L-1) and fucoxanthin production (9.19 mg L-1) than in conventional diatom media. Furthermore, increasing the bicarbonate concentration from 2 to 10 mM enhanced the maximum biomass and fucoxanthin production in FDM by 2.7 fold and 1.5 fold, respectively. Remarkably, the introduction of aeration to the modified FDM (MFDM) led to a substantial increase in the maximum biomass and fucoxanthin production of N. palea HY1, exhibiting 3.8-fold and 4.1-fold enhancement, respectively, compared to FDM alone. These findings suggest that optimizing the cultivation of N. palea HY1 using MFDM could provide an alternative to marine sources for fucoxanthin production. [ABSTRACT FROM AUTHOR]

Background: As coronavirus disease 2019 (COVID-19) transmission depends on factors such as demography, comorbidity, and patterns of daily activity, a better understanding of the societal factors of the infection among students would be useful in planning prevention strategies. However, no studies to date have focused on societal factors associated with COVID-19 transmission among students. Purpose: This study aimed to characterize the factors of a student population associated with COVID-19 transmission in the metropolitan city of Seoul, South Korea. Methods: We analyzed the epidemiological data for laboratory-confirmed (reverse transcription polymerase chain reaction) COVID-19 cases collected by the Korea Disease Control and Prevention Agency and Ministry of Education from January 2020 to October 2021. We calculated the global Moran’s index, local Moran’s index, and Getis-Ord’s index. A spatial regression analysis was performed to identify sociodemographic predictors of COVID-19 at the district level. Results: The global spatial correlation estimated by Moran’s index was 0.082 for the community population and 0.064 for the student population. The attack rate of adults aged 30– 59 years (P=0.049) was associated with an increased risk of COVID-19 attack rates in students, whereas the number of students per primary- (P=0.003) and middle- (P=0.030) school class was inversely associated with risk of COVID-19 attack among students. Conclusion: We found that COVID-19 transmission was more attributable to the community-level burden in students than adults. We recommend that public health initiatives target initiatives that protect students from COVID-19 when the community carries a high burden of infection. [ABSTRACT FROM AUTHOR]

Background/Aims: We aimed to evaluate the clinical characteristics and long-term prognosis of elderly-onset ulcerative colitis (EOUC) in Korean patients over a 30-year period using a well-established population-based cohort in the Songpa-Kangdong district of Seoul, Korea. Methods: Clinical characteristics and prognosis were compared between two groups: EOUC, defined as UC diagnosed in individuals aged ≥60 years and non-EOUC (N-EOUC), defined as UC diagnosed in individuals aged 18 to 59 years. Results: We identified 99 patients with EOUC (10.3%) and 866 patients with N-EOUC (89.7%) between 1986 and 2015. During the median follow-up of 104.5 months, the overall exposure to medications was comparable between patients with EOUC and N-EOUC (p=0.091 for corticosteroids, p=0.794 for thiopurines, and p=0.095 for anti-tumor necrosis factor agents). The cumulative risks of disease outcomes were also comparable between patients with EOUC and N-EOUC (22.4% vs 30.4% for proximal disease extension [p=0.351], 11.9% vs 18.1% for hospitalization [p=0.240], and 2.3% vs 1.8% for colectomy [p=0.977]) at 10 years after diagnosis. Multivariate Cox regression analysis revealed that corticosteroid use at diagnosis was an independent predictor of proximal disease extension (hazard ratio [HR], 6.216; 95% confidence interval [CI], 1.314 to 28.826) and hospitalization (HR, 11.241; 95% CI, 3.027 to 41.742) in patients with EOUC. Conclusions: In this population-based study from Korea, the pattern of medication use seemed comparable between the EOUC and N-EOUC groups. Moreover, patients with EOUC and those with N-EOUC have a similar disease course in terms of proximal disease extension, hospitalization, and colectomy. [ABSTRACT FROM AUTHOR]

PM2.5 is a WHO-designated first-class carcinogen and coping with high-concentration situations with high human risk is becoming more important. In particular, Korea has a high concentration of PM2.5 in winter due to its geographical characteristics, which can be largely divided into foreign inflows and domestic atmospheric stability. To determine this, wind patterns and air pressure data were analyzed representatively and episodes about high concentration phenomena were classified. In this study, high-concentration PM2.5 episodes, where the daily average PM2.5 concentration in Seoul exceeded 35 µg/m³ between October 2019 to March 2020, were analyzed case-by-case. The criteria for the separation of consecutive episodes were established. Then, the designated episodes were classified into four categories based on cause: atmospheric stagnation, combination of causes, penetration from abroad, and accumulation. To identify the causes of the episodes, wind direction, wind speed data, wind roses, and air quality forecast modeling data obtained from "Air Korea" were studied. Fifteen episodes were identified and analyzed and each were given a classification type. Furthermore, the phenomenon of high-concentration episodes was summarized after detailed individual analysis of the episodes. As a result of case analysis, just before there was an inflow from abroad due to strong wind speed, a characteristic of low PM2.5 concentration of air quality as a kind of cleaning effect could be found. In addition, alarm-level PM2.5 concentrations of 75 µg/m³ or higher were often made by external inflow. This will contribute towards identifying the main causes of high PM2.5 concentration episodes in Korea when it is applied over a longer time period. [ABSTRACT FROM AUTHOR]

Background The natural course of Crohn's disease (CD), with continuing relapses and remissions, leads to irreversible intestinal damage. Early adoption of immunomodulator therapy has been proposed in order to address this; however, it is still uncertain whether early immunomodulator therapy could affect the natural course of the disease in real practice. We evaluated the efficacy of such therapy on the prognosis of newly diagnosed patients with CD. Methods This retrospective study included 168 patients who were newly diagnosed with CD and who started treatment at Severance Hospital, Seoul, Korea between January 2006 and March 2013. The short- and long-term outcomes were compared between patients treated with early immunomodulator therapy and those treated with conventional therapy. Results A Kaplan-Meier analysis identified that administration of immunomodulators within 6 months after diagnosis of CD was superior to conventional therapy in terms of clinical remission and corticosteroid-free remission rates (P = 0.043 and P = 0.035). However, there was no statistical significance in the disease relapse rate between the two groups (P = 0.827). Patients with a baseline elevated CRP level were more likely to relapse (P < 0.005). Drug-related adverse events were more frequent in the early immunomodulator therapy group than in the conventional therapy group (P = 0.029). Conclusions Early immunomodulator therapy was more effective than conventional therapy in inducing remission, but not in preventing relapse. Baseline high CRP level was a significant indicator of relapse. [ABSTRACT FROM AUTHOR]

To identify the primary factor affected the decreased PM10 concentration in Seoul which is the capital city of Korea, wind speed and emissions in 2003 and 2004 were analyzed. The level of air pollution is intense in Seoul and continually increased since the late 1990s. However the concentration of PM10 has been greatly declined recently. In particular, the concentration of PM10 decreased 14% in 2003 and 2004 excluding the Asian dust periods. It is suggested that the major factors for the decrease are differences in wind speed between the two years and the period of constant breeze. In 2003, intense Asian dust events happened frequently and it increased the concentration of total PM10. The intense dust events were influence by the speed and duration of the wind. It is considered that the meteorological condition was the primary drive for the change of the concentration of PM10. The decreased emissions seem to be the additional factor for the change in the concentration of PM10. [ABSTRACT FROM AUTHOR]

This article discusses a study which compared the survival rates assessed by the seventh TNM staging system for gastric cancer of the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) with those by the sixth system. Investigators analyzed database on patients with gastric cancer who underwent surgery at Seoul National University Hospital in Korea between 1986 and 2006. The study revealed that the seventh system provided a more detailed classification of prognosis than the sixth system.

A Long-Path DOAS (LP-DOAS) developed by GIST was used to measure simultaneously atmospheric formaldehyde, monoaromatic hydrocarbons, and other trace gases over 740 and 2000 m beam paths at an urban site in Seoul, Korea during two field campaigns in February and August 2003. The mean concentrations of formaldehyde, benzene, toluene, m-xylene and p-xylene were measured to be 6.32 (± 2.41), 0.78 (± 0.32), 3.32 (± 1.87), 0.52 (± 0.24), and 0.38 (± 0.18) ppbv during the two measurement periods. Based on the analysis of the ratio of the OH⋅ -NO2 to OH⋅ -VOCs rate constants, it was possible to draw a conclusion that OH⋅ reacted preferentially with NO2 during the two measurement periods. Diurnal variation of formaldehyde was not typical of photochemically generated components during the two measurement periods in Seoul. Results from the linear regression fit analysis and diurnal variation of the measured species support that formaldehyde measured could be from primary sources (vehicle exhaust and heating burners) in winter and from primary and secondary sources (photochemical process) in summer. Monoaromatic hydrocarbons were likely emitted from the primary sources. [ABSTRACT FROM AUTHOR]

Presents a study assessing the effects of ambient air pollution on ischemic cardiovascular diseases among the elderly population in Seoul, South Korea. Estimation of the relative risks of hospitalization associated with an increase in pollution concentrations; Identification of sulphur dioxide as a significant risk factor for ischemic heart disease-related hospital admissions; Support to the hypothesis on the risk of elderly people to effects of air pollution at levels lower than the standards commonly adopted by many countries.

Background/Aims There is a lack of studies addressing mortality and causes of death in cohorts of Asian patients with intestinal Behcet disease (BD). This study aimed to assess causes of death in patients with intestinal BD and compare the related factors with mortality in a single center with a retrospective manner. Methods Total 543 patients who diagnosed intestinal BD in Severance Hospital, Yonsei University College of Medicine, Seoul, Korea, between January 1989 and December 2015 were enrolled to this study. Patient's baseline demographic and clinico-laboratory data were collected based on electronic and paper medical records. The baseline characteristics and treatment related outcomes were compared between dead intestinal BD patients and control group (n=115, age, sex and diagnosis periods were matched). All factors with p-value of <0.05 in the univariate analysis were included in a Cox proportional hazards multivariate model. Results Total 57 patients (10.5%) with intestinal BD died during study periods. The median duration of follow-up period was 32.1 months (range, 1 to 280 months). Main causes of death included systemic infection (n=18, 31.6%), malignancy (n=16, 28.1%) and cardiovascular disease (n=14, 24.6%). In multivariate analyses, combined hematologic disease (hazard ratio [HR], 5.016; 95% confidence interval [CI], 2.459 to 10.230), Charlson comorbidity index (HR, 1.485; 95% CI, 1.257 to 1.754), loss of weight (HR, 5.422; 95% CI, 2.368 to 12.416), extraintestinal manifestations at major vessels (HR, 2.211; 95% CI, 1.077 to 4.540) and disease distribution at upper gastrointestinal tract (HR, 3.949; 95% CI, 1.752 to 8.900) were associated with the risk of mortality. Conclusions Main causes of death were systemic infection, malignancy and cardiovascular disease. Combined hematologic disease, Charlson comorbidity index, loss of weight, extra-intestinal manifestations at major vessels and disease distribution at upper gastrointestinal tract were associated with increase of mortality in intestinal BD. [ABSTRACT FROM AUTHOR]