Exploring the relationship between work-family conflict and sleep disturbance: a study on stratification and interaction.

Introduction: Despite several studies on the association between work-family conflict (WFC) and sleep disturbances, a more comprehensive approach considering occupational factors is lacking. We aimed to analyze this association among Korean workers and the combined effects of WFC and job-related factors on sleep disturbance. Methods: Data on paid workers from the sixth Korean Working Conditions Survey were analyzed. Odds ratios (ORs) with 95% confidence intervals (CIs) for sleep disturbances with WFC were calculated using a multiple logistic regression model among Korean workers. Furthermore, stratification and interaction analyses were conducted between WFC and socioeconomic factors related to sleep disturbance. Results: Among the 24,923 workers (male: 11,752, female: 13,171) examined, 35.40% of males and 39.95% of females experienced sleep disturbances. In both sexes, the WFC group was significantly associated with sleep disturbance [adjusted OR (95% CI): male, 2.90 [2.67-3.16]; female, 2.54 [2.35-2.74]]. According to the stratification analysis, the association between sleep disturbance and WFC was prominent among younger and highly educated individuals, those engaged in quick returns, and larger companies in both sexes. In the interactions between WFC, quick return, occupation, and company size on sleep disturbance, there were significant additive associations, except between WFC and occupation among female workers. Conclusion: This study highlights the association between WFC and sleep disturbances in male and female workers and emphasizes the importance of maintaining work-life balance.

Socioeconomic Disparities in the Association Between All-Cause Mortality and Health Check-Up Participation Among Healthy Middle-Aged Workers: A Nationwide Study.

BACKGROUND: This study assessed the relationship between non-participation in health check-ups and all-cause mortality and morbidity, considering socioeconomic status. METHODS: Healthy, middle-aged (35-54 years) working individuals who maintained either self-employed or employee status from 2006-2010 were recruited in this retrospective cohort study from the National Health Insurance Service in Korea. Health check-up participation was calculated as the sum of the number of health check-ups in 2007-2008 and 2009-2010. Adjusted hazard ratio (HR) and 95% confidence interval (CI) of all-cause mortality were estimated for each gender using multivariable Cox proportional hazard models, adjusting for age, income, residential area, and employment status. Interaction of non-participation in health check-ups and employment status on the risk of all-cause mortality was further analyzed. RESULTS: Among 4,267,243 individuals with a median 12-year follow-up (median age, 44; men, 74.43%), 89,030 (2.09%) died. The proportion (number) of deaths of individuals with no, one-time, and two-time participation in health check-ups was 3.53% (n = 47,496), 1.66% (n = 13,835), and 1.33% (n = 27,699), respectively. The association between health check-up participation and all-cause mortality showed a reverse J-shaped curve with the highest adjusted HR (95% CI) of 1.575 (1.541-1.611) and 1.718 (1.628-1.813) for men and women who did not attend any health check-ups, respectively. According to the interaction analysis, both genders showed significant additive and multiplicative interaction, with more pronounced additive interaction among women who did not attend health check-ups (relative excess risk due to interaction, 1.014 [0.871-1.158]). CONCLUSION: Our study highlights the significant reverse J-shaped association between health check-up participation and all-cause mortality. A pronounced association was found among self-employed individuals, regardless of gender.

The significant association between quick return and depressive symptoms and sleep disturbances in paid workers: A nationwide survey.

Objectives: Although many studies have examined the association between shift work and depression or insomnia, few studies have examined the relationship between quick return (QR) to work and depressive symptoms, regardless of shift work. Thus, in this study, we aimed to assess the association between depressive symptoms (DS)/sleep disturbances (SDs) and QR. Methods: Data from the 6th Korean Working Conditions Survey (2020) were used for this study. Paid workers aged between 20 and 65 years were included. DS were defined using the World Health Organization Well-Being Index (WHO-5) with a cut-off 50, and SD was defined as the occurrence of the following symptoms several times per month: difficulty in falling asleep, waking up in the middle of the night, or feeling tired even after waking up. QR was defined as "at least one case where the working interval between leaving work and the next day's work was < 11 h in the past month." Multivariable logistic regression was performed to estimate the adjusted odd ratios (aORs) and 95% confidence intervals (CIs). Mediation analysis was conducted to examine whether SD was a significant mediator in the association between QR and DS. Results: Among the 27,554 participants, DS occurred in 8,277 patients, while SD occurred in 6,264 patients. The aORs (95% CIs) of DS and SD by QR were 2.01 (1.78-2.27) and 3.24 (2.87-3.66), respectively, after adjusting for age, gender, income, education, working hours, job status, working duration, region, shift work, and occupation. SD was a significant mediator in the association between QR and DS. Conclusion: QR is significantly associated with DS or SD regardless of demographic factors and the working environment. The significant relationship between QR and DS may be mediated by SD.

Association between physical risk factors and sleep disturbance among workers in Korea: The 5th Korean Working Conditions Survey.

OBJECTIVE: Sleep disturbance is associated with negative effects to workers' health and productivity; hence, it is important to find which population of workers are associated with sleep disturbance. This study aimed to investigate the association between physical risk factors (vibration, noise, high, and low temperatures) and sleep disturbance in the Korean working population. METHODS: We analyzed data on 29,213 paid workers from the 5th Korean Working Conditions Survey. Individual and occupational characteristics, physical risk factors exposure, and sleep disturbance were collected using self-reported questionnaires. To assess the association between physical risk factors and sleep disturbance, the chi-square test and multivariable logistic regression models were conducted. All statistical analyses were performed in sex-based subgroups. RESULTS: We observed that all physical risk factors are associated with sleep disturbance. The adjusted odds ratios (95% confidence interval [CI]) of severe exposure to vibration, noise, high and low temperature were 1.69 (CI:1.47-1.94), 2.52 (CI:2.17-2.92), 3.09 (CI:2.69-3.56), and 1.96 (CI:1.68-2.28) in male workers and 2.27 (CI:1.89-2.72), 3.52 (CI:2.92-4.24), 3.30 (CI:2.81-3.87), and 2.87 (CI:2.44-3.38) in female workers, respectively. The prevalence of sleep disturbance increased with increased exposure to physical risk factors, indicating a dose-response relationship. CONCLUSIONS: Physical risk factors exposure in the workplace was associated with sleep disturbance of workers, indicating a dose-response relationship. Given the impact of sleep disturbance on workers' health and efficiency, it may be important to control exposure to physical risk factors in the working environment with regards to sleep conditions.

The Association between New-Onset Depressive Symptoms and Participating in Medical Check-Ups among Elderly Individuals.

The association between adherence to medical check-ups and new-onset depressive symptoms, after adjusting for comprehensive risk factors such as social characteristics, remains unclear. This study aimed to assess the association between mental health and participating in medical check-ups. The survey data of participants aged 60 to 89 were recruited from the seventh Korean Longitudinal Study on Aging. The primary outcome was new-onset depressive symptoms within 2 years measured using the Center for Epidemiologic Studies Depression Scale. Participating in medical check-ups was defined as undergoing biennial medical check-ups. Multivariable logistic regression was performed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) with consideration of a 2-year time lag. Among 4255 participants, the prevalence of new-onset depressive symptoms was 7.36% (n = 313). The prevalence of non-participation in medical check-ups was 11.96% (n = 509). The adjusted OR of new-onset depressive symptoms by non-participation in medical check-ups was 1.65 [95% CI 1.22-2.24; p = 0.001] after adjusting for various demographic, behavioral, occupational, and social participation characteristics. Our findings demonstrated a significant inverse relationship between participation in medical check-ups and new-onset depressive symptoms. It is necessary to monitor and manage depressive symptoms in vulnerable elderly individuals who do not participate in medical check-ups.

The Association between Replacement Drivers and Depressive Symptoms.

A replacement driver is a type of gig worker who provides driving services to the target point with the drunk driver's own car. This study aimed to examine the association of replacement drivers (ref: paid workers) with depressive symptoms. Information on replacement drivers was collected through online/offline surveys. Data from the 8th Korea National Health and Nutrition Examination Survey were applied to construct the control group. The Patient Health Questionnaire-9; ≥5 points was defined as depressive symptoms. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were calculated by performing multivariable logistic regression analysis. The mean age of replacement drivers was 56.11. The prevalence of depressive symptoms in replacement drivers and controls were 49.63% and 12.64%, respectively. Replacement drivers showed a higher association with depressive symptoms than paid workers (aOR 7.89, 95% CI [5.53-11.26]). This relationship was prominent in the older, low-education, and low-income groups. Linear discriminant analysis was the most effective in predicting depressive symptoms among the machine learning models. Using the replacement driver feature increased the AUC values of the models. Given the strong association between depressive symptoms and replacement drivers, in-depth studies to establish guidelines to prevent mental diseases among replacement drivers are required.

Clinical efficacy of biomarkers for evaluation of volume status in dialysis patients.

Volume status is a key parameter for cardiovascular-related mortality in dialysis patients. Although N-terminal pro-B-type natriuretic peptide (NT-proBNP), myeloperoxidase, copeptin, and pro-adrenomedullin have been reported as volume markers, the relationship between body fluid status and volume markers in dialysis patients is uncertain. Therefore, we investigated the utility of volume status biomarkers based on body composition monitor (BCM) analyses.We enrolled pre-dialysis, hemodialysis (HD), and peritoneal dialysis (PD) patients and age- and gender-matched healthy Korean individuals (N = 80). BCM and transthoracic echocardiography were performed and NT-proBNP, myeloperoxidase, copeptin, and pro-adrenomedullin concentrations were measured. Relative hydration status (ΔHS, %) was defined in terms of the hydration status-to-extracellular water ratio with a cutoff of 15%, and hyperhydrated status was defined as ΔHS > 15%.Although there were no significant differences in total body water, extracellular water, or intracellular water among groups, mean amount of volume overload and hyperhydrated status were significantly higher in HD and PD patients compared with control and pre-dialysis patients. Mean amount of volume overload and hyperhydrated status were also significantly associated with higher NT-proBNP and pro-adrenomedullin levels in HD and PD patients, although not with myeloperoxidase or copeptin levels. Furthermore, they were significantly associated with cardiac markers (left ventricular mass index, ejection fraction, and left atrial diameter) in HD and PD patients compared with those in the control and pre-dialysis groups.On the basis of increased plasma NT-proBNP and pro-adrenomedullin concentrations, we might be able to make predictions regarding the volume overload status of dialysis patients, and thereby reduce cardiovascular-related mortality through appropriate early volume control.

Multidimensional gender discrimination in workplace and depressive symptoms.

BACKGROUND: Discrimination is associated with depressive symptoms and other negative health effects, but little is known about the mental health risks of workplace gender discrimination. We aimed to investigate the association of workplace gender discrimination and depressive symptoms among employed women in South Korea. METHODS: The 6th wave (2016) survey datasets of the Korean Longitudinal Survey of Women and Family (KLoWF) were analyzed for 2,339 respondents who are identified as wage workers. Depressive symptoms were evaluated by the short-form (10-item) Center for Epidemiological Studies-Depression scale. Association of workplace gender discrimination and depressive symptoms was assessed using multivariate logistic regression, adjusted for potential confounding variables including age, income satisfaction, education level, marital status, and currently diagnosed disease. We then measured the age effect using age stratification multivariate logistic regression model. RESULTS: Women who experienced gender discrimination at workplace had higher odds of depressive symptoms regardless of the type of the discrimination including hiring, promotion, work assignments, paid wages, and firing. These associations were consistent in younger women below 40 years of age in regard to hiring, promotion, paid wages and firing, whereas inconsistent among older women above 40 years of age. LIMITATIONS: We did not investigate the effect of workplace gender discrimination on depressive symptoms in a longitudinal manner. CONCLUSIONS: Workplace gender discrimination was found to be significantly associated with depressive symptoms after adjustment for socio-demographic factors. Further, women under 40 years of age were especially vulnerable to workplace gender discrimination.

Does suicidal ideation and depressive mood of parents affect their adolescent children's mental health?

BACKGROUND: Depression in adolescence is a social problem that has detrimental effects on an individual's physical and mental health and increases health care burden on families and society. This study investigates the connection between mental illness among parents and their adolescent children in Korea. METHODS: The sample included parents of 5315 adolescents (12-24 years) and data were obtained from the Korea National Health and Nutrition Survey (KNHANES) from 2007 to 2017. Family based comprehensive questionnaires were used. Multivariate logistic regression models were performed to estimate odds ratios (ORs) at 95% confidence intervals (95% CIs). RESULTS: The main findings showed that daughters with depressed mothers were 1.92 times more likely to experience depression and 1.64 times more likely to have suicidal ideations. In particular, when father was suicidal, his daughter had a 2.59 times higher risk of suicidal thoughts than father was not depressed and had no suicidal thoughts. Sons' depressive mood was rarely affected by the psychological status of mothers and fathers. LIMITATION: There are under-report issue of feelings and study design is cross-sectional. CONCLUSIONS: This study showed gender differences in the association between parents' and adolescents' experience of depression. Thus, the daughter's psychological state was found to be strongly associated with the psychological state of both parents.

External Airborne-agent Exposure Increase Risk of Digestive Tract Cancer.

Previous studies have suggested that in addition to respiratory system cancers, exposure to external airborne agents (EAAs) may also affect the risk of digestive tract cancer. However, previous epidemiological studies have been limited. To clarify this relationship, we conducted a Workers' Korea National Health Insurance Service cohort study. The EAA exposure group comprised participants who had ever visited a hospital as an inpatient for 'lung diseases due to external agents'. The reference population comprised men from the general working population. The EAA exposure group and reference group included a total of 98,666 and 79,959,286 person-years, respectively. Age-adjusted standardized incident rates (SIRs) with 95% confidence intervals (95%CI) were calculated for each 5-year age stratum. The SIR (95% CI) of EAA exposure was 1.30 (1.19-1.38) for all digestive tract cancers. The highest risk associated with EAA exposure was observed for oral cancer, followed by esophageal and stomach cancers [SIRs (95%CI): 3.96 (3.02-4.78), 3.47(2.60-4.25), and 1.34(1.17-1.47), respectively.] These statistically significant associations did not be attenuated in a subgroup analysis using logistic regression adjusted for age, smoking and alcohol consumption. Our findings suggest that EAA exposure should address risk reduction of both digestive tract and respiratory system cancers.

Injury epidemiology of workers by age, sex and industrial classification using the medical claim data of National Health Insurance in South Korea, 2012-2015: a population-based retrospective study.

OBJECTIVES: This study aimed to evaluate the risk of inpatient hospitalisation for all-cause injuries, according to age, sex and industrial classification (IC) in South Korea. DESIGN: A population-based retrospective study. SETTING AND PARTICIPANTS: Data from the National Health Insurance Database on medical claims for the entire population of South Korean workers aged 25-59 years from January 2012 to December 2015 were retrieved. We observed 30 900 712 person-years (63.1%) in male workers and 18 105 272 person-years (36.9%) in female workers. MAIN OUTCOME MEASURES: The inpatient hospitalisation for all-cause injury was defined as admission for which the principal diagnosis included S00-T98 in the Korean version of International Classification of Diseases-10 codes. RESULTS: Of 788 575 hospitalisations for all-cause injuries from 2012 to 2015, there were 565 107 cases in male workers (1 828.8 per 100 000 person-years) and 223 468 cases in female workers (1 234.3 per 100 000 person-years). The top five ICs with hospitalisation rate ratios (HRR) for all-cause injuries in both sexes compared with the financial intermediation IC included agriculture, hunting and forestry (HRR (95% CI); male: 2.09 (1.98 to 2.20); female: 1.53 (1.40 to 1.67)); mining and quarrying (male: 2.05 (1.92 to 2.19); female: 1.54 (1.27 to 1.87)) and fishing (male: 1.68 (1.57 to 1.80); female: 1.71 (1.51 to 1.93)). A U-shaped relationship occurred between age and risk for injuries in males; however, only a linear relationship was shown in females, regardless of IC. CONCLUSIONS: The risk of injures varied by IC. The workers in agriculture, hunting, forestry, mining, quarrying and fishing were more vulnerable to injuries. The risk for injuries were higher among men and the age effect on this risk differed by sex. Thus, policy makers need to consider specific measures for prevention of injuries according to age, sex and IC.

Deep Learning Algorithms with Demographic Information Help to Detect Tuberculosis in Chest Radiographs in Annual Workers' Health Examination Data.

We aimed to use deep learning to detect tuberculosis in chest radiographs in annual workers' health examination data and compare the performances of convolutional neural networks (CNNs) based on images only (I-CNN) and CNNs including demographic variables (D-CNN). The I-CNN and D-CNN models were trained on 1000 chest X-ray images, both positive and negative, for tuberculosis. Feature extraction was conducted using VGG19, InceptionV3, ResNet50, DenseNet121, and InceptionResNetV2. Age, weight, height, and gender were recorded as demographic variables. The area under the receiver operating characteristic (ROC) curve (AUC) was calculated for model comparison. The AUC values of the D-CNN models were greater than that of I-CNN. The AUC values for VGG19 increased by 0.0144 (0.957 to 0.9714) in the training set, and by 0.0138 (0.9075 to 0.9213) in the test set (both p < 0.05). The D-CNN models show greater sensitivity than I-CNN models (0.815 vs. 0.775, respectively) at the same cut-off point for the same specificity of 0.962. The sensitivity of D-CNN does not attenuate as much as that of I-CNN, even when specificity is increased by cut-off points. Conclusion: Our results indicate that machine learning can facilitate the detection of tuberculosis in chest X-rays, and demographic factors can improve this process.

Efficacy and safety of CKD-11101 (darbepoetin-alfa proposed biosimilar) compared with NESP in anaemic chronic kidney disease patients not on dialysis.

OBJECTIVE: To evaluate the efficacy and safety of CKD-11101 (biosimilar darbepoetin-alfa, Chong Kun Dang Pharm.) compared with NESP® in treatment of anaemia in patients with chronic kidney disease not on dialysis. CLINICAL TRIAL REGISTRATION: NCT03431623. METHOD: In this multi-centre, randomized, double-blind study, patients were treated with CKD-11101 and NESP. The efficacy evaluation period (EEP) was 24 weeks, during which patients were treated every 2 weeks. All patients who completed the EEP were treated with CKD-11101 every 2 weeks for the first 4 weeks and every 4 weeks for the safety evaluation period (SEP), which was from 24 weeks to 52 weeks. The primary efficacy endpoint was the change in mean haemoglobin (Hb) level from baseline to end of EEP and mean dose needed to achieve the target Hb. RESULTS: The mean Hb level was increased in both groups during the EEP (both p < 0.001). The difference in mean Hb level change between the two groups was 0.01 g/dL (95% CI = -0.213-0.242), indicating that CKD-11101 was equivalent to NESP. The difference in mean administration dose between groups was -1.40 mcg (95% CI = -6.859-4.059) included in the equivalent range. The incidence of AEs and ADRs was not different between the two groups, and the frequency of ADRs was favourable in both groups (1.2% in CKD-11101 vs 7.7% in the NESP to CKD-11101 conversion group). CONCLUSION: CKD-11101 has an equivalent therapeutic effect as NESP in chronic kidney disease patients with renal anaemia. CKD-11101 can be safely used for long-term treatment and in patients converted from NESP.

Long Commute Time and Sleep Problems with Gender Difference in Work-Life Balance: A Cross-sectional Study of More than 25,000 Workers.

BACKGROUND: There is a lack of statistical analysis investigating the relationship between sleep problems and commute time in Korea. We aimed to analyze the association between representative health symptoms, sleep disturbances, and commute time according to working hours in Korea. METHODS: The 4th Korean Working Conditions Survey data were used for analysis, and unpaid family workers and workers who work fewer than three days in a week were excluded. Commute time, working hours, and sleep hours were assessed using self-reported questionnaires. Odds ratios (ORs) with 95% confidence intervals (CIs) for sleep problems were calculated using a multivariate logistic regression model with ≤10 min commute time as the reference group. RESULTS: Among a total of 28,804 workers (men = 14,945, women = 13,859), 2.6% of men and 3.2% of women experienced sleep problems. In both sexes, long commute time (51-60 minutes and >60 minutes) showed an increased OR [men, 2.03 (CI = 1.32-3.13) and 2.05 (CI = 1.33-3.17); women, 1.58 (CI = 1.05-2.39) and 1.63 (CI = 1.06-2.50), respectively]. In stratification analysis of working hours, long commute time (51-60 and > 60 minutes) showed an increased OR in men working >40 hours/week [2.08 (CI = 1.16-3.71) and 1.92 (CI = 1.08-3.41), respectively]. Furthermore, long commute time (41-50, 51-60, and >60 minutes) showed an increased OR in women working >40 hours/week [2.40 (CI = 1.27-4.55), 2.28 (CI = 1.25-4.16), and 2.19 (CI = 1.17-4.16), respectively]. Moreover, commute time >60 minutes showed an increased OR in women working ≤40 hours/week [1.96 (CI = 1.06-3.62)]. CONCLUSION: This large cross-sectional study highlights that long commute time is related to sleep problems in both sexes. Shorter commute times and decreased working hours are needed to prevent sleep problems in workers.

The Correlations among Depressive Symptoms, Cognitive Performance and Serum BDNF Levels in the Patients with Chronic Kidney Disease.

OBJECTIVE: In the current study, we investigated whether there are relations among depressive symptoms, cognitive performance and serum BDNF levels in the patients with chronic kidney disease (CKD). METHODS: Sixty patients with CKD and 65 healthy controls participated. Depressive symptoms were evaluated with Beck depression inventory (BDI) and Hamilton Depression Rating Scale (HDRS). Mini-Mental State Examination included in the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (MMSE-KC) assessment packet was used for the evaluation of overall cognitive function. To assess memory function, the Korean version of the Hopkins Verbal Learning Test (K-HVLT) was used. BDNF levels were measured using an enzyme-linked immunosorbent assay (ELISA) kit. RESULTS: The CKD patients showed more depressive symptoms when compared with controls. The depressive symptoms and cognitive function were not associated with serum BDNF levels in the CKD patients. CONCLUSION: In the current study, CKD patients had more depressive symptoms when compared controls. However, the serum BDNF levels of CKD patients were not associated with depressive symptoms and cognitive functions. These findings suggested that the serum BDNF levels may not be reflect the cognitive function and depressive mood state in the CKD patients.

Population pharmacokinetics of levofloxacin in Korean patients.

Levofloxacin (LVFX) has different effects depending on the area under the concentration-time curve (AUC)/minimum inhibitory concentration (MIC) ratio. While AUC can be expressed as dose/clearance (CL), we measured serial concentrations of LVFX in Koreans and tried to set a Korean-specific equation, estimating the CL of the antibiotic. In total, 38 patients, aged 18-87 years, received once daily intravenous LVFX doses of 500 mg or 250 mg, depending on their renal function. Four plasma samples were obtained according to a D optimal sampling design. The population pharmacokinetic (PK) parameters of LVFX were estimated using non-linear mixed-effect modeling (NONMEM, ver. 7.2). The CL of LVFX was dependent on creatinine clearance (CLCR) as a covariate. The mean population PK parameters of LVFX in Koreans were as follows: CL (l/hour) = 6.19 × (CLCR/75)(1.32). The CL of LVFX in Koreans is expected to be lower than that in Western people.

Plasma PCSK9 in nephrotic syndrome and in peritoneal dialysis: a cross-sectional study.

BACKGROUND: Serum total and low-density lipoprotein (LDL) cholesterol levels are elevated in patients with nephrotic syndrome and those with kidney failure treated by peritoneal dialysis (PD), who are characterized by heavy losses of protein in urine and peritoneal dialysate, respectively. Hypercholesterolemia in nephrotic syndrome is associated with and largely due to acquired LDL receptor (LDLR) deficiency. Because PCSK9 (proprotein convertase subtilisin/kexin type 9) promotes degradation of LDLR, we tested the hypothesis that elevation of LDL cholesterol levels in patients with nephrotic syndrome and PD patients may be due to increased PCSK9 levels. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: Patients with nephrotic syndrome or treated by PD or hemodialysis and age- and sex-matched healthy Korean individuals (n=15 in each group). PREDICTOR: Group and serum total and LDL cholesterol levels. OUTCOMES: Plasma PCSK9 concentration. MEASUREMENTS: Concentrations of fasting serum PCSK9, lipids, and albumin, and urine protein excretion. RESULTS: Mean serum total and LDL cholesterol levels in patients with nephrotic syndrome (317.9±104.2 [SD] and 205.9±91.1mg/dL) and PD patients (200.0±27.6 and 126.7±18.5mg/dL) were significantly (P<0.05) higher than in hemodialysis patients (140.9±22.9 and 79.1±19.5mg/dL) and the control group (166.5±26.5 and 95.9±25.2mg/dL). This was associated with significantly (P<0.05) higher plasma PCSK9 levels in patients with nephrotic syndrome (15.13±4.99ng/mL) and PD patients (13.30±1.40ng/mL) than in the control (9.19±0.60ng/mL) and hemodialysis (7.30±0.50ng/mL) groups. Plasma PCSK9 level was directly related to total and LDL cholesterol concentrations in the study population (r=0.559 [P<0.001] and r=0.497 [P<0.001], respectively). LIMITATIONS: Small number of participants may limit generalizability. CONCLUSIONS: Nephrotic syndrome and PD are associated with higher plasma PCSK9 concentration, which can contribute to elevation of LDL levels by promoting LDLR deficiency.

Immunogenicity of recombinant human erythropoietin in Korea: a two-year cross-sectional study.

Immunogenicity of erythropoietin (EPO) is related with pure red cell aplasia (PRCA). We sought to determine the prevalence of antibody (Ab)-mediated PRCA in Korea and threshold diagnostic criteria by dual parameters: Ab titer and neutralizing activity. This study was a multi-center, cross-sectional study for two years. In the first year study (1 YS), 209 samples suspected to be EPO resistance were collected. In the second year study (2 YS), all the patients who consented to participate (N = 946) were enrolled. In 1 YS, we found three and six serum samples that were positive and borderline for anti-EPO Abs, respectively. The first three patients had neutralizing activity (NT) and were diagnosed as PRCA. In 2 YS, seven patients were anti-EPO positives and six had borderline levels. Among them, one patient with NT was diagnosed as PRCA and one with NT as aplastic anemia. The prevalence of PRCA was 0.106%. The correlation analysis of the 22 patients who had anti-EPO Ab showed that dual crossed cut-off lines (anti-EPO Ab titer ≥ 40 ng/ml, % NT ≥ 25%) were able to clearly isolate red cell aplasia. We suggest novel diagnostic criteria for diagnosis and prediction of Ab-mediated PRCA with data from both Ab titer assays and NT bioassays.

Urinary concentrating defect in hypothyroid rats: role of sodium, potassium, 2-chloride co-transporter, and aquaporins.

Hypothyroidism is associated with impaired urinary concentrating ability in humans and animals. The purpose of this study was to examine protein expression of renal sodium chloride and urea transporters and aquaporins in hypothyroid rats (HT) with diminished urinary concentration as compared with euthyroid controls (CTL) and hypothyroid rats replaced with L-thyroxine (HT+T). Hypothyroidism was induced by aminotriazole administration. Body weight, water intake, urine output, solute and urea excretion, serum and urine osmolality, serum creatinine, 24-h creatinine clearance, and fractional excretion of sodium were comparable among the three groups. However, with 36 h of water deprivation, HT rats demonstrated significantly greater urine flow rates and decreased urine and medullary osmolality as compared with CTL and HT+T rats at comparable plasma vasopressin concentrations. Western blot analyses revealed decreased renal protein abundance of transporters, including Na-K-2Cl, Na-K-ATPase, and NHE3, in HT rats as compared with CTL and HT+T rats. Protein abundance of renal AQP1 and urea transporters UTA(1) and UTA(2) did not differ significantly among study groups. There was however a significant decrease in protein abundance of AQP2, AQP3, and AQP4 in HT rats as compared with CTL and HT+T rats. These findings demonstrate a decrease in the medullary osmotic gradient secondary to impaired countercurrent multiplication and downregulation of aquaporins 2, 3, and 4 as contributors to the urinary concentrating defect in the hypothyroid rat.