Comparison of the Prevalence of Antibodies to SARS-CoV-2 in 9954 Recruits in the Korean Army Training Center with the General Korean Population of Equivalent Age Between September and November, 2020.

BACKGROUND Understanding the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be a useful tool when studying spread of the disease. This study aimed to compare the prevalence of antibodies to SARS-CoV-2 in 9954 recruits in the Korean Army Training Center with the general Korean population age <30 years between September and November, 2020. MATERIAL AND METHODS At the Korean Army Training Center, samples were taken from 9954 men from September to November, 2020. Participants were randomly enlisted healthy adult men. The data were compared with 4,205,265 samples from the Korean general population. Men age <30 years were used, as this is similar to the age range of the military recruits. RESULTS Among military recruits, 31 subjects (0.31%) were positive for the antibody, while the Korean male population had 3757 (0.09%) positive individuals. Among these 31 men, 13 were previously diagnosed by PCR, while 18 (58.06%) had no history related to the disease. Positive military recruits were mostly from 2 regional clusters. The first cluster was Daegu and Gyeongbuk areas (1.97% and 0.80%, respectively), which had an outbreak in March, 2020. The second cluster was Gyeonggi and Seoul, or capital areas (0.23% and 0.20%, respectively), which currently has high PCR positivity. Overall, seroprevalence was 3.49 times higher in study subjects. CONCLUSIONS The high seroprevalence of antibodies to SARS-CoV-2 between September and November 2020 in a densely populated military academy in Korea may have been an indicator for the resulting outbreak of COVID-19 in winter 2020-21, which highlights the importance of asymptomatic spread from the young and healthy to the general population.

Association Between Serum Albumin Levels and Obesity and Risk of Developing Chronic Kidney Disease Using Data from the Korean Multi-Rural Communities Cohort (MRCohort) Population Database.

BACKGROUND The Multi-Rural Communities Cohort (MRCohort) was established as part of the Korean Genome and Epidemiology Study, which identified risk factors for cardiovascular diseases in the population between January 2005 and December 2011. This was a prospective study, aimed to investigate the association between serum albumin levels and the risk of developing chronic kidney disease (CKD) in obese patients using data from the MRCohort population database. MATERIAL AND METHODS For analysis, we selected a total of 9695 people from the MRCohort from 2004 to 2013: 3105 people from Goryeong, 3183 from Yangpyeong, and 3407 from Namwon, without previous history of myocardial infarction, cerebrovascular disease, cancer, and CKD, or missing values on confounders. As a result, 2300 metabolically healthy participants were studied as a whole, and then by body mass index of >23 kg/m². The groups were divided into 4 subgroups by albumin quartiles, and the effects of albumin levels compared to the lowest quartile were studied by Cox proportional hazard analysis, after adjusting for potential confounders. RESULTS The results showed that the highest quartile of albumin, compared to the lowest quartile, was a protective factor of CKD development only in the overweight and obese group with adjusted hazard ratio (HR)=0.38 (95% confidence interval (CI) 0.16-0.95, p<0.05). In the normal-weight group, results were insignificant, with adjusted HR=0.54 (95% CI 0.24-1.25, not significant). CONCLUSIONS Data from the Korean MRCohort population database showed that obesity and increased serum albumin levels were protective factors for the development of CKD.

Development and validation of multiplex PCR assay for differentiating tunas and billfishes.

Commercially available tunas and billfishes are generally processed as steaks, making it difficult to visually distinguish between the two. We developed and validated species-specific primers to prevent the adulteration of tunas by billfishes. Tunas and billfishes primers were designed on the cytochrome oxidase subunit I. Multiplex PCR bands obtained were 579 bp, 291 bp and 114 bp for tunas, billfishes and internal control. Sensitivity was determined to be 5 ng for tunas and billfishes. A total of 50 samples were monitored: 49 for tunas and 1 for billfish. As a result of the monitoring, the fake tunas did not show due to the agreement between product name and the raw material of the wrapping paper. Our results indicate that the species-specific primers developed in this study are suitable for differentiating tunas and billfishes. The newly developed multiplex PCR assay is a time and cost effective technique for determining the authenticity of tunas and billfishes.

Association of Dietary Potassium Intake with the Development of Chronic Kidney Disease and Renal Function in Patients with Mildly Decreased Kidney Function: The Korean Multi-Rural Communities Cohort Study.

BACKGROUND Dietary potassium has negative outcomes in patients with mildly impaired kidney function, while having positive outcomes in patients with hypertension. The association of dietary potassium intake with chronic kidney disease (CKD) development, with presence of hypertension, was studied in the Korean rural population with mildly impaired kidney function. MATERIAL AND METHODS From 3 rural areas of Korea, 5064 participants age ≥40 with CKD stage 2 at baseline were recruited. Patients were classified according to the quartile of dietary potassium intake. Newly developed CKD, defined as estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m² at the time of follow-up, and eGFR decline, defined as eGFR decrease >15% at follow-up, were studied. The effect of dietary potassium on CKD development and eGFR decline were studied by Cox proportional hazard models. The association of potassium with blood pressures and C-reactive protein was also studied to examine the underlying mechanisms. RESULTS Compared to 8.6% in normotensives, 15.7% of hypertensives developed CKD. The hazard ratio (HR) (95% confidence interval) of CKD was lower in high potassium diet only in hypertensives, with 0.60 (0.37-0.99) in the highest quartile. The eGFR decline was also lower in patients with higher potassium diet, with 0.70 (0.50-0.98) in Q3 and 0.54 (0.34-0.85) in Q4. Potassium intake has also been shown to decrease high diastolic blood pressure development (>90 mmHg) in hypertensives at 0.45 (0.25-0.83). CONCLUSIONS Dietary potassium was associated with lower risk of CKD development and eGFR decline, and this association was observed only in hypertensives.

Effect of Uric Acid on the Development of Chronic Kidney Disease: The Korean Multi-Rural Communities Cohort Study.

OBJECTIVES: Several studies have investigated the effects of serum uric acid (SUA) levels on chronic kidney disease (CKD), with discrepant results. The effect of SUA levels on CKD development was studied in the Korean rural population. METHODS: A total of 9695 participants aged ≥40 years were recruited from 3 rural communities in Korea between 2005 and 2009. Of those participants, 5577 who participated in the follow-up and did not have cerebrovascular disease, myocardial infarction, cancer, or CKD at baseline were studied. The participants, of whom 2133 were men and 3444 were women, were grouped into 5 categories according to their quintile of SUA levels. An estimated glomerular filtration rate of <60 mL/min/1.73 m2 at the time of follow-up was considered to indicate newly developed CKD. The effects of SUA levels on CKD development after adjusting for potential confounders were assessed using Cox proportional hazard models. RESULTS: Among the 5577 participants, 9.4 and 11.0% of men and women developed CKD. The hazard ratio (HR) of CKD was higher in the highest quintile of SUA levels than in the third quintile in men (adjusted HR, 1.60; 95% confidence interval [CI], 1.02 to 2.51) and women (adjusted HR, 1.56; 95% CI, 1.14 to 2.15). Furthermore, CKD development was also more common in the lowest quintile of SUA levels than in the third quintile in men (adjusted HR, 1.83; 95% CI, 1.15 to 2.90). The effect of SUA was consistent in younger, obese, and hypertensive men. CONCLUSIONS: Both high and low SUA levels were risk factors for CKD development in rural Korean men, while only high levels were a risk factor in their women counterparts.

Polymorphisms in the 3'-UTR of SCD5 gene are associated with hepatocellular carcinoma in Korean population.

The purpose of the study was to assess the relationship between polymorphisms of the SCD5 and MMP1 gene and hepatocellular carcinoma (HCC). The gene polymorphisms with a minor allele frequency (MAF) > 0.05 were selected eight SNPs (rs6840, rs1065403, rs3821974, and rs3733230 in 3'-UTR; rs4693472, rs3733227, rs1848067, and rs6535374 in intron region) of SCD5 gene and two SNPs (rs1799750 and rs1144393 in promoter region) of MMP1 gene. The genotype of SCD5 and MMP1 gene SNPs were determined by direct sequencing and pyrosequencing, respectively. One hundred sixty-two patients with HCC and two hundred twenty-five control subjects were recruited in Korean male population. In terms of genotype frequencies, SCD5 genotype TC, GA, AG, and CG of rs6840, rs1065403, rs3821974, and rs3733230, respectively were higher in control group than HCC. In addition, these genotype decreased the risk (rs6840; OR 0.55, 95% CI 0.31-0.99; rs1065403; OR 0.46, 95% CI 0.26-0.83; rs3821974; OR 0.56, 95% CI 0.31-0.99; rs3733230; OR 0.62, 95% CI 0.34-1.12) of HCC, which may work as a prevention of HCC. At least one minor allele carrier of SCD5 gene polymorphisms were related to decreased risk of HCC for AFP cut-point levels > 200 or > 400 ng/ml, respectively. Our results indicate that polymorphisms in the 3'-UTR of the SCD5 gene may associated with HCC in the Korean male population.

Verification of learner's differences by team-based learning in biochemistry classes.

PURPOSE: We tested the effect of team-based learning (TBL) on medical education through the second-year premedical students' TBL scores in biochemistry classes over 5 years. METHODS: We analyzed the results based on test scores before and after the students' debate. The groups of students for statistical analysis were divided as follows: group 1 comprised the top-ranked students, group 3 comprised the low-ranked students, and group 2 comprised the medium-ranked students. Therefore, group T comprised 382 students (the total number of students in group 1, 2, and 3). To calibrate the difficulty of the test, original scores were converted into standardized scores. We determined the differences of the tests using Student t-test, and the relationship between scores before, and after the TBL using linear regression tests. RESULTS: Although there was a decrease in the lowest score, group T and 3 showed a significant increase in both original and standardized scores; there was also an increase in the standardized score of group 3. There was a positive correlation between the pre- and the post-debate scores in group T, and 2. And the beta values of the pre-debate scores and "the changes between the pre- and post-debate scores" were statistically significant in both original and standardized scores. CONCLUSION: TBL is one of the educational methods for helping students improve their grades, particularly those of low-ranked students.