Trace fear conditioning is characterized by a stimulus-free trace interval (TI) between the conditioned stimulus (CS) and the unconditioned stimulus (US), which requires an array of brain structures to support the formation and storage of associative memory. The entorhinal cortex (EC) has been proposed to provide essential neural code for resolving temporal discontinuity in conjunction with the hippocampus. However, how the CS and TI are encoded at the neuronal level in the EC is not clear. In Exp. 1, we tested the effect of bilateral pre-training electrolytic lesions of EC on trace vs. delay fear conditioning using rats as subjects. We found that the lesions impaired the acquisition of trace but not delay fear conditioning confirming that EC is a critical brain area for trace fear memory formation. In Exp. 2, single-unit activities from EC were recorded during the pretraining baseline and post-training retention sessions following trace or delay conditioning. The recording results showed that a significant proportion of the EC neurons modulated their firing during TI after the trace conditioning, but not after the delay fear conditioning. Further analysis revealed that the majority of modulated units decreased the firing rate during the TI or the CS. Taken together, these results suggest that EC critically contributes to trace fear conditioning by modulating neuronal activity during the TI to facilitate the association between the CS and US across a temporal gap.

Purpose: To determine the metabolic influence of the traditional Korean diet (K-diet), which has been regarded as a healthy diet, we investigated the profile of urine organic acids that are intermediates of various types of metabolism including energy metabolism. Methods: Ten women aged 50–60 years were recruited and randomly divided into 2 diet groups, K-diet and control diet, the latter of which is a Westernized Korean diet that is commonly consumed by Koreans nowadays. Before and after the 2-week intervention, 46 urine organic acids were determined using LC/MS/MS, along with clinical parameters. Results: The average concentrations of succinate (4.14 ± 0.84 μg/mg creatinine vs. 1.49 ± 0.11, p = 0.0346) and hydroxymethylglutarate (3.67 ± 0.36 μg/mg creatinine vs. 2.97 ± 0.29, p = 0.0466), both of which are intermediates of energy metabolism, decreased in the K-diet group after the 2-week intervention, but these were not observed in the control diet group. In particular, the average concentration of succinate in the K-diet group was lower than that in the control group (3.33 ± 0.56 μg/mg creatinine vs. 1.49 ± 0.11, p = 0.0284) after 2 weeks. The concentrations of two tryptophan metabolites, 5-hydroxyindolacetate (3.72 ± 0.22 μg/mg creatinine vs. 3.14 ± 0.21, p = 0.0183) and indican (76.99 ± 8.35 μg/mg creatinine vs. 37.89 ± 10.06, p = 0.0205) also decreased only in the K-diet group. After the 2-week intervention, the concentration of kynurenate, another tryptophan metabolite, was lower in the K-diet group than that in the control diet group (3.96 ± 0.51 μg/mg creatinine vs. 2.90 ± 0.22, p = 0.0356). Interestingly, the urine level of kynurenate was positively correlated with BMI (r = 0.61424, p = 0.0003) and total cholesterol (r = 0.46979, p = 0.0088), which decreased only in the K-diet group (239.40 ± 15.14 mg/dL vs. 198.20 ± 13.25, p = 0.0163). Conclusion The K-diet alters the urinary excretion of organic acids involved in energy metabolism and tryptophan metabolism, suggesting the influence of the K-diet on these types of metabolism. Urine organic acids changed by the K-diet may serve as biomarkers in future studies.

Background: and PurposeImpulse-control disorder is an important nonmotor symptom of Parkinson's disease (PD) that can lead to financial and social problems, and be related to a poor quality of life. A nationwide multicenter prospective study was performed with the aim of validating the Korean Version of the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease Rating Scale (K-QUIP-RS). Methods: The K-QUIP-RS was constructed using forward and backward translation, and pretesting of the prefinal version. PD patients on stable medical condition were recruited from 27 movement-disorder clinics. Participants were assessed using the K-QUIP-RS and evaluated for parkinsonian motor and nonmotor statuses and for PD-related quality of life using a predefined evaluation battery. The test–retest reliability of the K-QUIP-RS was assessed over an interval of 10–14 days, and correlations between the KQUIP-RS and other clinical scales were analyzed. Results: This study enrolled 136 patients. The internal consistency of the K-QUIP-RS was indicated by a Cronbach's α coefficient of 0.846, as was the test–retest reliability by a Guttman split-half coefficient of 0.808. The total K-QUIP-RS score was positively correlated with the scores for depression and motivation items on the Unified PD Rating Scale (UPDRS), Montgomery-Asberg Depression Scale, and Rapid-Eye-Movement Sleep-Behavior-Disorders Questionnaire. The total K-QUIP-RS score was also correlated with the scores on part II of the UPDRS and the PD Quality of Life-39 questionnaire, and the dopaminergic medication dose. Conclusions The K-QUIP-RS appears to be a reliable assessment tool for impulse-control and related behavioral disturbances in the Korean PD population.

Mortalities from cardiovascular disease in Korea have decreased markedly over the past three decades. The major cardiovascular and metabolic risk factors, however, remain prevalent, and their burden on health is large. The Cardiovascular and Metabolic Diseases Etiology Research Center (CMERC) planned a cohort study in order to identify novel risk factors and to develop evidence-based prevention strategies of cardiovascular and metabolic diseases. The CMERC deliberately designed two prospective cohorts, a community-based general population cohort (the CMERC cohort) and its sister cohort (a hospital-based high-risk patient cohort), covering a broad spectrum of cardiovascular and metabolic diseases. This paper describes the CMERC cohort study of community-dwelling adults aged 30 to 64 years. A total of 8097 adults completed baseline measurement between 2013 and 2018. Baseline measurements assessed socio-demographic factors, medical history, health-related behaviors, psychological health, social network and support, anthropometry, body composition, and resting blood pressure and comprised electrocardiography, carotid artery ultrasonography, fasting blood analysis, and urinalysis. Both active follow-up through an annual telephone survey and a 5-year on-site health examination survey and passive follow-up through secondary data linkage with national databases, such as national death records, have been applied. Researchers interested in collaborative research may contact the corresponding author.
Adult ; Anthropometry ; Blood Pressure ; Body Composition ; Cardiovascular Diseases ; Carotid Arteries ; Cohort Studies ; Death Certificates ; Electrocardiography ; Fasting ; Follow-Up Studies ; Humans ; Information Storage and Retrieval ; Korea ; Metabolic Diseases ; Mortality ; Prospective Studies ; Republic of Korea ; Risk Factors ; Siblings ; Telephone ; Ultrasonography ; Urinalysis

OBJECTIVE: To evaluate the clinical characteristics, therapeutic interventions, and outcomes of patients with septic shock admitted to the emergency department (ED). METHODS: This study was a preliminary, descriptive analysis of a prospective, multi-center, observational registry of the EDs of 10 hospitals participating in the Korean Shock Society. Patients aged 19 years or older who had a suspected or confirmed infection and evidence of refractory hypotension or hypoperfusion were included. RESULTS: A total of 468 patients were enrolled (median age, 71.3 years; male, 55.1%; refractory hypotension, 82.9%; hyperlactatemia without hypotension, 17.1%). Respiratory infection was the most common source of infection (31.0%). The median Sepsis-related Organ Failure Assessment score was 7.5. The sepsis bundle compliance was 91.2% for lactate measurement, 70.3% for blood culture, 68.4% for antibiotic administration, 80.3% for fluid resuscitation, 97.8% for vasopressor application, 68.0% for central venous pressure measurement, 22.0% for central venous oxygen saturation measurement, and 59.2% for repeated lactate measurement. Among patients who underwent interventions for source control (n=117, 25.1%), 43 (36.8%) received interventions within 12 hours of ED arrival. The in-hospital, 28-day, and 90-day mortality rates were 22.9%, 21.8%, and 27.1%, respectively. The median ED and hospital lengths of stay were 6.8 hours and 12 days, respectively. CONCLUSION: This preliminary report revealed a mortality of over 20% in patients with septic shock, which suggests that there are areas for improvement in terms of the quality of initial resuscitation and outcomes of septic shock patients in the ED.
Central Venous Pressure ; Compliance ; Emergency Service, Hospital ; Humans ; Hyperlactatemia ; Hypotension ; Lactic Acid ; Male ; Mortality ; Oxygen ; Patient Care Bundles ; Prospective Studies ; Resuscitation ; Sepsis ; Shock* ; Shock, Septic*

Although the etiologies of cardiovascular disease (CVD) are widely understood, the goal of finding a globally effective solution for preventing CVD is unrealistic. Therefore, we aimed to conduct a community-based prospective study on the prevention and management of CVD in Korean adults. This study was designed to recruit 8,000 healthy adults over the course of 5 years. The baseline assessment includes a wide range of established CVD risk factors, including demographic characteristics, medical history, health behaviors, psychological conditions, body size and composition, blood pressure, the augmentation index, carotid ultrasonography, an electrocardiogram, and biochemical indicators, as well as some novel factors, such as social network characteristics, exposure to environmental pollutants, inflammatory markers, hemostatic markers, and immunosenescence markers. Annual telephone interviews and follow-up health examinations at 5-year intervals after the baseline assessment are planned to collect information on changes in health status and its determinants. Additionally, indirect follow-up using secondary data sources will be conducted to obtain information on health services utilization and death. So far, more than 6,000 adults have been enrolled during the first three and a half years, and almost all participants have been tracked by annual telephone follow-up surveys. The data have been uploaded to iCReaT, the clinical research information management system of the Korea National Institute of Health.
Adult ; Blood Pressure ; Body Size ; Cardiovascular Diseases ; Cohort Studies ; Electrocardiography ; Environmental Pollutants ; Follow-Up Studies ; Health Behavior ; Health Services ; Humans ; Immunosenescence ; Information Management ; Information Storage and Retrieval ; Interviews as Topic ; Korea ; Metabolic Diseases ; Prospective Studies ; Risk Factors ; Telephone ; Ultrasonography

Although the etiologies of cardiovascular disease (CVD) are widely understood, the goal of finding a globally effective solution for preventing CVD is unrealistic. Therefore, we aimed to conduct a community-based prospective study on the prevention and management of CVD in Korean adults. This study was designed to recruit 8,000 healthy adults over the course of 5 years. The baseline assessment includes a wide range of established CVD risk factors, including demographic characteristics, medical history, health behaviors, psychological conditions, body size and composition, blood pressure, the augmentation index, carotid ultrasonography, an electrocardiogram, and biochemical indicators, as well as some novel factors, such as social network characteristics, exposure to environmental pollutants, inflammatory markers, hemostatic markers, and immunosenescence markers. Annual telephone interviews and follow-up health examinations at 5-year intervals after the baseline assessment are planned to collect information on changes in health status and its determinants. Additionally, indirect follow-up using secondary data sources will be conducted to obtain information on health services utilization and death. So far, more than 6,000 adults have been enrolled during the first three and a half years, and almost all participants have been tracked by annual telephone follow-up surveys. The data have been uploaded to iCReaT, the clinical research information management system of the Korea National Institute of Health.
Adult ; Blood Pressure ; Body Size ; Cardiovascular Diseases ; Cohort Studies* ; Electrocardiography ; Environmental Pollutants ; Follow-Up Studies ; Health Behavior ; Health Services ; Humans ; Immunosenescence ; Information Management ; Information Storage and Retrieval ; Interviews as Topic ; Korea ; Metabolic Diseases* ; Prospective Studies ; Risk Factors ; Telephone ; Ultrasonography

BACKGROUND AND OBJECTIVES: Low-density lipoprotein cholesterol (LDL-C), an established cardiovascular risk factor, can be generally determined by calculation from total cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations. The aim of this study was to compare LDL-C estimations using various formulas with directly measured LDL-C in a community-based group and hospital-based group among the Korean population. SUBJECTS AND METHODS: A total of 1498 participants were classified into four groups according to triglyceride concentrations as follows: <100, 100–199, 200–299, and ≥300 mg/dL. LDL-C was calculated using the Friedewald, Chen, Vujovic, Hattori, de Cordova, and Anandaraja formulas and directly measured using a homogenous enzymatic method. Pearson's correlation coefficients, intraclass correlation coefficients (ICC), Passing & Bablok regression, and Bland-Altman plots were used to evaluate the performance of six formulas. RESULTS: The Friedewald formula had the highest accuracy (ICC=0.977; 95% confidence interval 0.974-0.979) of all the triglyceride ranges, while the Vujovic formula had the highest accuracy (ICC=0.876; 98.75% confidence interval 0.668–0.951) in people with triglycerides ≥300 mg/dL. The mean difference was the lowest for the Friedewald formula (0.5 mg/dL) and the percentage error was the lowest for the Vujovic formula (30.2%). However, underestimation of the LDL-C formulas increased with triglyceride concentrations. CONCLUSION: The accuracy of the LDL-C formulas varied considerably with differences in triglyceride concentrations. The Friedewald formula outperformed other formulas for estimating LDL-C against a direct measurement and the Vujovic formula was suitable for hypertriglyceridemic samples; it could be used as an alternative cost-effective tool to measure LDL-C when the direct measurement cannot be afforded.
Cardiovascular Diseases* ; Cholesterol* ; Humans ; Lipoproteins* ; Methods ; Risk Factors ; Triglycerides

BACKGROUND AND OBJECTIVES: We investigated the inter-arm difference in blood pressure of the general Korean population to identify associated factors. SUBJECTS AND METHODS: A total of 806 participants aged 30 to 64 years without history of major cardiovascular disease were analyzed in this cross-sectional study. They participated in the Cardiovascular and Metabolic Disease Etiology Research Center cohort study that began in 2013. Brachial blood pressure was measured simultaneously for both arms using an automated oscillometric device equipped with two cuffs in seated position. After five minutes of rest, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured three times. The average of the three measurements was used for analysis. Multivariate logistic regression models were used to identify factors associated with inter-arm differences in blood pressure. RESULTS: The mean inter-arm difference was 3.3 mmHg for SBP and 2.0 mmHg for DBP. Large inter-arm differences (≥10 mmHg) in SBP and in DBP were found in 3.7% and 0.9% of subjects, respectively. A large inter-arm difference in SBP was associated with mean SBP (p=0.002) and C-reactive protein (p=0.014) while a large inter-arm different in DBP was only associated with body mass index (p=0.015). Sex, age, and anti-hypertensive medication use were not associated with differences in inter-arm blood pressure. CONCLUSION: Large inter-arm difference in blood pressure is only present in a small portion of healthy Korean adults. Our findings suggest that high SBP, chronic inflammation, and obesity may be associated with larger difference in inter-arm blood pressure.
Adult ; Arm ; Blood Pressure* ; Body Mass Index ; C-Reactive Protein ; Cardiovascular Diseases ; Cohort Studies ; Cross-Sectional Studies ; Humans ; Inflammation ; Logistic Models ; Metabolic Diseases ; Obesity ; Posture

OBJECTIVE: During the past 20 years, over 1,400 doctors have been certified as emergency physicians in Korea. The number of scientific publications in the field of emergency medicine has also increased. This study aims to evaluate the research productivity of academic emergency physicians in South Korea. METHODS: Articles published from 1996 to 2015 by authors affiliated with Korean emergency departments were retrieved using Pubmed, Embase, and Web of Science. Research productivity was analyzed quantitatively to ascertain the number of articles for publication type and year. The performance of these articles was also analyzed qualitatively using impact factor, citation number, and Hirsch index. Bibliometric analysis was performed by researching Web of Science, Scopus, and Google Scholar. RESULTS: A total of 858 articles with 293 Korean authors as the first or corresponding authors were published across 191 journals. The number of publications increased continuously. The most common publication type was original article (n=618), the most commonly studied research topic was resuscitation medicine (n=110), and the average impact factor of the original articles was 2.158. The highest h-index was 17 and, using Web of Science, the maximum number of citations was found to be 85. CONCLUSION: This study suggests that the research productivity of Korean authors in the emergency medicine field has progressed steadily during the last 10 years. However, qualitative indexes, such as the number of citations and h-index value, remain low.
Bibliometrics* ; Efficiency* ; Emergencies* ; Emergency Medicine* ; Emergency Service, Hospital ; Humans ; Journal Impact Factor ; Korea* ; Publications ; Research Personnel ; Resuscitation