In Silico and In Vitro multiple analysis approach for screening naturally derived ligands for red seabream aryl hydrocarbon receptor.

The aryl hydrocarbon receptor (AHR) is a key ligand-dependent transcription factor that mediates the toxic effects of compounds such as dioxin. Recently, natural ligands of AHR, including flavonoids, have been attracting physiological and toxicological attention as they have been reported to regulate major biological functions such as inflammation and anti-cancer by reducing the toxic effects of dioxin. Additionally, it is known that natural AHR ligands can accumulate in wildlife tissues, such as fish. However, studies in fish have investigated only a few ligands in experimental fish species, and the AHR response of marine fish to natural AHR ligands of various other structures has not been thoroughly investigated. To explore various natural AHR ligands in marine fish, which make up the most fish, it is necessary to develop new screening methods that consider the specificity of marine fish. In this study, we investigated the response of natural ligands by constructing in vitro and in silico experimental systems using red seabream as a model species. We attempted to develop a new predictive model to screen potential ligands that can induce transcriptional activation of red seabream AHR1 and AHR2 (rsAHR1 and rsAHR2). This was achieved through multiple analyses using in silico/ in vitro data and Tox21 big data. First, we constructed an in vitro reporter gene assay of rsAHR1 and rsAHR2 and measured the response of 10 representatives natural AHR ligands in COS-7 cells. The results showed that FICZ, Genistein, Daidzein, I3C, DIM, Quercetin and Baicalin induced the transcriptional activity of rsAHR1 and rsAHR2, while Resveratrol and Retinol did not induce the transcriptional activity of rsAHR isoforms. Comparing the EC50 values of the respective compounds in rsAHR1 and rsAHR2, FICZ, Genistein, and Daidzein exhibited similar isoform responses, but I3C, Baicalin, DIM and Quercetin show the isoform-specific responses. These results suggest that natural AHR ligands have specific profiling and transcriptional activity for each rsAHR isoform. In silico analysis, we constructed homology models of the ligand binding domains (LBDs) of rsAHR1 and rsAHR2 and calculated the docking energies (U_dock values) of natural ligands with measured in vitro transcriptional activity and dioxins reported in previous studies. The results showed a significant correlation (R2=0.74(rsAHR1), R2=0.83(rsAHR2)) between docking energy and transcriptional activity (EC50) value, suggesting that the homology model of rsAHR1 and rsAHR2 can be utilized to predict the potential transactivation of ligands. To broaden the applicability of the homology model to diverse compound structures and validate the correlation with transcriptional activity, we conducted additional analyses utilizing Tox21 big data. We calculated the docking energy values for 1860 chemicals in both rsAHR1 and rsAHR2, which were tested for transcriptional activation in Tox21 data against human AHR. By comparing the U_dock energy values between 775 active compounds and 1085 inactive compounds, a significant difference (p<0.001) was observed between the U_dock energy values in the two groups, suggesting that the U_dock value can be applied to distinguish the activation of compounds. Furthermore, we observed a significant correlation (R2=0.45) between the AC50 of Tox21 database and U_dock values of human AHR model. In conclusion, we calculated equations to translate the results of an in silico prediction model for ligand screening of rsAHR1 and rsAHR2 transactivation. This ligand screening model can be a powerful tool to quantitatively estimate AHR transactivation of major marine agents to which red seabream may be exposed. The study introduces a new screening approach for potential natural AHR ligands in marine fish, based on homology model-docking energy values of rsAHR1 and rsAHR2, with implications for future agonist development and applications bridging in silico and in vitro data.

Assessment of Occupational Health Risks for Maintenance Work in Fabrication Facilities: Brief Review and Recommendations.

Background: This study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. Objectives: The objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. Methods: A literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. Results: Maintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. Conclusion: Further research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

Development of occupation-based exposure matrix of lead for Korean workers: challenges and opportunities.

OBJECTIVES: Industry- and occupation-based carcinogen exposure matrices play a pivotal role in preventing occupational cancer. While the Korean CARcinogen EXposure (K-CAREX) has been developed in recent years to assess exposure prevalence and intensity by industry, the feasibility of constructing an occupation-based exposure matrix remains unexplored. Hence, the objective of this study is to explore the potential of combining the nationwide work environment measurement database (WEMD) and the special health examination database (SHED) to develop a comprehensive occupation-based exposure matrix. METHODS: The WEMD provides information on airborne lead measurements, including industry codes, but it does not include data related to occupations. In contrast, the SHED contains information on both occupation and blood lead levels. By integrating these 2 databases, we attempted to assess airborne lead exposure levels by occupation. Additionally, we performed a rank correlation analysis to compare the airborne exposure levels with corresponding blood lead levels according to occupation. RESULTS: A total of 35 425 workers who both wore air samplers for lead and underwent special health examinations for lead were extracted between 2019 and 2021. An occupation-based exposure matrix was developed to evaluate the intensity of lead exposure across a range of occupations, encompassing 51 minor occupations and 70-unit occupations. Rank correlation analyses showed strong positive correlations between airborne lead and blood lead measurements according to occupation. CONCLUSIONS: Our study findings suggest that combining 2 nationwide surveillance databases can be an effective approach for creating an occupation-based exposure matrix. However, our results also highlight several limitations that need to be addressed in future studies to improve the accuracy and reliability of such matrices.

Gallbladder perforation in acute acalculous vs. calculous cholecystitis: a retrospective comparative cohort study with 10-year single-center experience.

BACKGROUND: Gallstones are a well-known risk factor for acute cholecystitis. However, their role as a risk factor for gallbladder perforation (GBP) remains unclear. Therefore, this study aimed to determine the effect of gallstones on the development of GBP. MATERIALS AND METHODS: This large-scale retrospective cohort study enroled consecutive patients who underwent cholecystectomy for acute cholecystitis. The primary endpoint was the role of gallstones as a risk factor for developing GBP. Secondary endpoints included the clinical characteristics of GBP, other risk factors for GBP, differences in clinical outcomes between patients with acalculous cholecystitis (AC) and calculous cholecystitis (CC), and the influence of cholecystectomy timing. RESULTS: A total of 4497 patients were included in this study. The incidence of GBP was significantly higher in the AC group compared to the CC group (5.6% vs. 1.0%, P <0.001). However, there were no differences in ICU admission and hospital stay durations. The incidence of overall complications was significantly higher in the AC group than in the CC group (2.2% vs. 1.0%, P <0.001). Patients with AC had a higher risk of developing GBP than those with CC (odds ratio, 5.00; 95% CI, 2.94-8.33). In addition, older age (≥60 years), male sex, comorbidities, poor performance status, and concomitant acute cholangitis were associated with the development of GBP. Furthermore, the incidence of GBP was significantly higher in the delayed cholecystectomy group than in the early cholecystectomy group (2.0% vs. 0.9%, P <0.001). CONCLUSIONS: AC is a significant risk factor for GBP. Furthermore, early cholecystectomy can significantly reduce GBP-related morbidity and mortality.

Evaluation on the Sex-Specific Association Between Cigarette Smoke Exposure and Inflammation Markers-C-Reactive Protein and White Blood Cell Count.

INTRODUCTION: Cigarette smoke increases peripheral white blood cell (WBC) count. However, the dose-dependent association between smoking and C-reactive protein (CRP), an important inflammatory marker, has been reported as inconsistent. AIMS AND METHODS: Here, we evaluated the associations between smoking and CRP using both smoking questionnaires and urine cotinine as exposure markers. The Korea National Health and Nutrition Examination Survey data were used for analyzing the associations. Multiple regression analyses were performed to examine the associations between cigarette smoke exposure, as assessed by questionnaires and urine cotinine, and health effects, as measured by CRP and WBC count, controlling for potential confounders. The confounders, including age, sex, body mass index, blood pressure, cholesterol, glucose, alanine aminotransferase, and uric acid, were selected a priori based on the literature. RESULTS: A total of 11 435 participants were included for analysis. For the exposure-response relationship, the results indicated a significant increase in CRP levels in male smokers compared to male nonsmokers (p = .002), whereas no significant increase was found in female smokers compared to female nonsmokers (p = .680). For the dose-response relationship, a significant positive association was observed between urine cotinine and CRP in male smokers (p = .018), whereas no significant association was found in female smokers (p = .508). WBC count consistently showed significant exposure-response and dose-response relationships in both sexes. CONCLUSIONS: WBC count was found to be a consistent effect marker of cigarette smoke exposure, while the association between CRP level and smoking was inconsistent and varied by sex. The sex-specific response to cigarette smoke exposure warrants further exploration in future studies. IMPLICATIONS: Cigarette smoke exposure is known to increase inflammation and has been thought to increase CRP, a significant inflammation marker. However, recent studies have reported conflicting results regarding the dose-dependent association between cigarette smoke exposure and CRP. This study found that the association between smoking and CRP is inconsistent and varies by sex, showing significant exposure response in men but not in women. Furthermore, the study suggests that WBC count is a more consistent marker for cigarette smoke exposure.

Evaluation of Temporal Trends of Lead Exposure in Korean Workers Using Workplace Monitoring Data.

BACKGROUND: Lead, which is widely used in various industrial settings, is a major health hazard for manufacturing workers. Therefore, control of lead exposure has been implemented in an effort to prevent lead-related health problems. In this study, our aim was to evaluate temporal trends in occupational lead exposure in Korean lead workers using data from monitoring of workplace exposure. METHODS: A nationwide work environment monitoring database, data from a work environment monitoring institution, and data extracted from a review paper were utilized. Different versions of standard industrial classification codes were aligned with the 10th Korean Standard Industrial Classification, which is generally consistent with the 4th revision of the International Standard Industrial Classification. The multiple data sources were combined and temporal trends over the period from 1994-2021 were estimated. In addition, separate estimation of temporal trends in the storage battery manufacturing industry over the period from 1987-2021 was also performed. RESULTS: A total of 444,296 personal airborne lead measurements were used for the estimation process. The temporal trends in occupational exposure to lead declined by -6% annually over the study period. In particular, levels of lead exposure in the storage battery manufacturing industry showed a steeper decline of -12% annually. CONCLUSIONS: Findings of our study showed that occupational exposure to lead declined over the period from 1994 to 2021 in Korea. However, adverse effects of exposure to lead on health should be regarded with caution. The results will be useful in conduct of epidemiological studies examining lead-related effects on health.

Comparison of Two Types of Guidewires for Malignant Hilar Biliary Obstruction by Endoscopic Retrograde Cholangiopancreatography: A Randomized Controlled Trial.

Background: There is insufficient information regarding the optimal guidewire for managing malignant hilar biliary obstruction (MHBO). Therefore, a newly designed 0.025-inch guidewire was compared with the conventional 0.035-inch guidewire for selective cannulation of both intrahepatic ducts (IHDs) in patients with MHBO. Methods: Patients were randomly enrolled into the curved type newly designed 0.025-inch guidewire group (0.025 group) or the curved type conventional 0.035-inch guidewire group (0.035 group). The primary outcome was the selective cannulation rate of IHD. If the assigned guidewire failed to pass the stricture within 5 min, the crossover guidewire was selected. If the crossover guidewire failed to cross the stricture within the next 5 min, it was judged as a failed selective cannulation of both IHDs. Results: A total of 90 patients were enrolled (0.025 group, n = 47; 0.035 group, n = 43). There was no significant difference in baseline characteristics between the groups regarding sex, age, BMI, obstruction level, and clinical presentation. Four patients (8.5%) in the 0.025 group the cannulation of the IHD failed and the conventional 0.035-inch guidewire was substituted in a second attempt; the 0.035-inch guidewire failed to cross the stricture in all four patients. In the 0.035 group, eleven patients (25.6%) failed to achieve selective cannulation of IHD, and the 0.025-inch guidewire was substituted; the newly designed 0.025-inch guidewire crossed the stricture in ten of these (10/11, 90.9%). The selective cannulation rate of IHD was significantly higher in the 0.025 group (95.1% vs. 85.5%, p = 0.043). Conclusions: The 0.025 group exhibited a higher success rate for selective cannulation of both IHDs in MHBO than did the 0.035 group.

EUS-guided tissue acquisition using a novel torque technique is comparable with that of the fanning technique for solid pancreatic lesions: A multicenter randomized trial.

BACKGROUND: The torque and fanning techniques allow for multiple areas within pancreatic lesions to be targeted using different maneuvers and can, hence, enhance diagnostic outcomes. We compared the diagnostic performance of endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) for pancreatic masses using the torque and fanning techniques. METHODS: This multicenter randomized trial enrolled a total of 160 consecutive patients who underwent EUS-FNB for solid pancreatic tumors using either the torque or fanning technique. Three passes were permitted for each lesion, and the technique sequence was randomly assigned as either torque first or fanning first with the standard technique as a reference. RESULTS: The median quality score of the histological samples was significantly higher in the torque and fanning group than in the standard group (p < .001). Furthermore, the torque technique provided improved sensitivity of 93.38% and accuracy of 94.30%. The standard technique provided diagnostic sensitivity of 68.84% and accuracy of 72.96%, while the fanning technique showed sensitivity of 91.85% and accuracy of 93.04%. CONCLUSIONS: The new torque technique enables the acquisition of better-quality samples and can potentially increase the diagnostic outcomes in the EUS-FNB of pancreatic solid masses, with the same recommendations as those for the fanning technique.

Cholecystectomy Increases the Risk of Type 2 Diabetes in the Korean Population: Data From the National Health Insurance Cooperation Health Checkup 2010-2017.

OBJECTIVE: This study assessed whether cholecystectomy is a risk factor for newly developed type 2 diabetes mellitus (T2DM) in the Korean population. BACKGROUND: There is a lack of evidence that cholecystectomy is independently associated with insulin resistance and T2DM. METHODS: This study included all patients aged more than 20 years who had undergone cholecystectomy from 2010 to 2015 (n=55,166) and age-matched and sex-matched control subjects without cholecystectomy (n=110,332) using the National Health Insurance Service database. They were followed up until the date of newly developed T2DM or study end and the incidence of T2DM was traced over a maximum observation period of 7 years. RESULTS: Overall, 55,166 patients who underwent cholecystectomy and 110,332 age-matched and sex-matched controls were followed up for ∼4.7 years, during which, incident T2DM occurred in 5982 (3.61%) patients. Cholecystectomy was associated with 20% higher risk of T2DM after adjustment for all covariates. The cumulative incidence of T2DM also significantly increased in the cholecystectomy group for ∼7 years ( P <0.001). The adjusted hazard ratio (HR) for T2DM was the highest in the group with both cholecystectomy and obesity using the control without both cholecystectomy and obesity as a reference [HR=1.41, 95% confidence interval (CI): 1.29-1.56]. The group with cholecystectomy without obesity showed the comparable risk of incident T2DM compared with the group without cholecystectomy with obesity (HR=1.29, 95% CI: 1.20-1.40 for cholecystectomy without obesity and HR=1.24, 95% CI: 1.14-1.36 for control with obesity). CONCLUSIONS: These results provide evidence that cholecystectomy is associated with an increased risk of newly developed T2DM in the Korean population. Further research is required to elucidate the mechanism of the association between cholecystectomy and incident diabetes.

Ursodeoxycholic acid inhibits epithelial-mesenchymal transition, suppressing invasiveness of bile duct cancer cells: An in vitro study.

Epithelial-mesenchymal transition (EMT) features are associated with pathological severity in the progression and metastasis of various cancer types, including bile duct cancer (BDC). Our previous study demonstrated that ursodeoxycholic acid (UDCA) blocked the EGFR-MAPK signaling pathway and inhibited the invasion of BDC cells. The present study was performed to determine whether UDCA inhibits EMT and promotes the expression of E-cadherin to inhibit the invasion and aggressiveness of BDC. In addition, the present study aimed to confirm that the primary mechanism of inhibition of EMT by UDCA is related to the EGFR axis. Human extrahepatic BDC cells were cultured. The effect of UDCA on cell proliferation was evaluated using MTT assays. A cell death ELISA kit was used to measure apoptosis, and western blot assays or immunofluorescence staining assays measured the expression levels of various target proteins. The mRNA expression of Slug and ZEB1 was evaluated via reverse transcription-quantitative PCR. The invasiveness of BDC cells was estimated by invasion assays and western blot assays for focal adhesion kinase (FAK). UDCA inhibited the proliferation of BDC cells as effectively as gefitinib (an EGFR inhibitor), and the combination of UDCA and gefitinib revealed an additive effect on the proliferation of cells. UDCA and gefitinib induced apoptosis, and the combination of UDCA and gefitinib demonstrated an additive effect on apoptosis in BDC cells. UDCA restored the E-cadherin expression inhibited by EGF and suppressed N-cadherin expression increased by EGF as effectively as gefitinib. UDCA suppressed the Slug and ZEB1 mRNA expression induced by EGF in BDC cells. UDCA suppressed the invasiveness of BDC cells and FAK expression linked to the invasiveness of BDC. In conclusion, UDCA enhanced E-cadherin expression and suppressed N-cadherin expression through inhibition of the EGF-EGFR axis, contributing to the inhibition of EMT and invasiveness in BDC cells. Therefore, UDCA may be applied as an adjuvant or palliative antineoplastic agent and as a therapeutic option to enhance the effect of other chemotherapeutics.

Development of Korean CARcinogen EXposure: Assessment of the Exposure Intensity of Carcinogens by Industry.

Background: Occupational cancer is a global health issue. The Korean CARcinogen EXposure (K-CAREX), a database of CARcinogen EXposure, was developed for the Korean labor force to estimate the number of workers exposed to carcinogens by industry. The present study aimed to estimate the intensity of exposure to carcinogens by industry, in order to supply complementary information about CARcinogen EXposure intensity to the K-CAREX. Methods: We used nationwide workplace monitoring data from 2014 to 2016 and selected target carcinogens based on the K-CAREX list. We computed the 95th percentile levels of measurements for each industry by carcinogens. Based on the 95th percentile level relative to the occupational exposure limit, we classified the CARcinogen EXposure intensity into five exposure ratings (1-5) for each industry. Results: The exposure ratings were estimated for 21 carcinogenic agents in each of the 228 minor industry groups. For example, 3,058 samples were measured for benzene in the manufacturing industry of basic chemicals. This industry was assigned a benzene exposure rating of 3. Conclusions: We evaluated the CARcinogen EXposure ratings across industries in Korean workers. The results will provide information on the exposure intensity to carcinogens for integration into the K-CAREX. Furthermore, it will aid in prioritizing control efforts and identifying industries of concern.

Correlation between cholecystectomy and development of non-alcoholic liver disease in the mouse model.

Background: Several clinical studies have suggested a strong correlation between cholecystectomy and the incidence of non-alcoholic fatty liver disease (NAFLD) although the exact correlation and causal relationship are unclear. This study aimed to investigate whether cholecystectomy increases the incidence of NAFLD or aggravates pre-existing NAFLD. Methods: Standard diet-fed and high-fat (HF) diet-fed mice were subjected to sham operation and cholecystectomy. In study 1, 20 standard diet-fed C57BL/6N mice were sacrificed at months 1, 2, and 4 post-surgery. Meanwhile, in study 2, 25 HF diet-induced NAFLD C57BL/6N mice were biopsied at months 2 and 3 post-surgery and sacrificed at month 6 post-surgery. The hepatic fatty acid and bile acid metabolic pathways and the hepatic bile composition were evaluated. Results: The bodyweight and biochemical parameters (hepatic enzyme, triglyceride, and cholesterol levels) were not significantly different between the standard diet-fed sham and cholecystectomy groups. The NAFLD activity score and the levels of hepatocyte apoptosis markers (Krt18 expression and DNA fragmentation) and de novo lipid synthesis genes were not significantly different between the standard diet-fed sham and cholecystectomy groups. Cholecystectomy did not exacerbate hepatic steatosis, inflammation, and ballooning in the HF diet-fed mice. Hepatic bile acid composition was not markedly different in the sham and cholecystectomy groups fed on standard or HF diet. Cholecystectomy significantly downregulated Cyp7a1 and Cyp27a1 mRNA levels at months 1 and 4 post-surgery but did not affect the degree of steatosis and triglyceride levels. Analysis of bile acid metabolism revealed that taurine-conjugated bile acids were significantly downregulated in the standard diet-fed and high-fat diet-fed mice, but the histological and biochemical parameters were not markedly different. Conclusions: Cholecystectomy did not increase the incidence of NAFLD in standard diet-fed mice. Additionally, NAFLD incidence was not significantly different between the HF diet-fed sham and cholecystectomy groups. Furthermore, the histological parameters were not markedly different between the sham and cholecystectomy groups fed on standard or HF diet. These findings suggest that cholecystectomy does not induce NAFLD.

Clinical Impact of Sarcopenia on Cholangiocarcinoma.

Sarcopenia is considered an important factor affecting the prognosis of cancer patients. Only complete surgical resection confers the chance of curing cholangiocarcinoma with sarcopenia. However, the prognosis is poor, even for patients who undergo surgical resection. Data from 13 trials of patients with sarcopenia and intrahepatic cholangiocarcinoma (ICC) or perihilar cholangiocarcinoma (PHC) were collected and reviewed. During all trials, sarcopenia was assessed using the psoas muscle or total skeletal muscle at the L3 level on cross-sectional images. The data showed heterogeneity among the subjects and treatment options and discrepancies in methods of measuring muscle mass and setting the cut-off level. Despite conflicting results regarding morbidity, mortality, and recurrence, sarcopenia may be associated with poor overall survival and recurrence-free survival (RFS) for ICC patients. The impact of sarcopenia on the morbidity of ICC patients remains unclear. The impact of PHC on morbidity, mortality, and RFS is also unclear. Further well-designed studies are needed to elucidate the effects of sarcopenia on ICC and PHC.

Efficacy of Chenodeoxycholic Acid and Ursodeoxycholic Acid Treatments for Refractory Functional Dyspepsia.

Refractory functional dyspepsia (RFD) is diagnosed when symptoms persist for at least 6 months despite at least two medical treatments. No consensus treatment guidelines exist. The implicated causes of functional biliary dyspepsia are a narrowed cystic duct, Sphincter of Oddi dysfunction, microlithiasis, and gallbladder dyskinesia. We investigated the treatment effects of litholytic agents. RFD patients were prospectively enrolled in six tertiary medical centers. All subjects took chenodeoxycholic and ursodeoxycholic acids (CNU) twice daily for 12 weeks. We monitored their medication adherence, laboratory results, and complications. The 7-point global symptom scale test scores were determined before and after treatment. Of the 52 patients who were prospectively screened, 37 were included in the final analysis. The mean age was 51.3 years: 14 were males, and 23 were females. Before treatment, the mean number and duration of symptoms were 2.4 and 48.2 months, and a mean of 3.3 FD-related drugs were taken. The mean CNU adherence was 95.3%. The mean global symptom scale score decreased from 5.6 pretreatment to 2.6 posttreatment. The symptom improvement rate was 94.6% (35 out of 37 patients). The only adverse event was mild diarrhea (10.8%) that was resolved after conservative management. Conclusions: CNU improved the symptoms of RFD patients who did not respond to conventional medications. Litholytic agents are good treatment options for patients with RFD and biliary dyspepsia secondary to biliary microlithiasis. Further prospective, large-scale mechanistic studies are warranted.

Assessment of sunlight exposure across industries and occupations using blood vitamin D as a biomarker.

OBJECTIVE: Exposure to ultraviolet (UV) radiation from sunlight induces the production of essential vitamin D, whereas overexposure to sunlight leads to skin cancer. Sunlight exposure has been measured using questionnaires, dosimeters, and vitamin D levels. Several studies have measured vitamin D in the working population; however, these studies were limited to certain occupations such as farmers and construction workers. In the present study, we evaluated sunlight exposure using blood vitamin D as an exposure surrogate across industries and occupations. METHODS: The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide study representing the Korean population. We analyzed data from KNHANES between 2008 and 2009. We examined the association between vitamin D levels and pertinent personal, seasonal, residential, and occupational factors. Furthermore, we developed a multiple regression model with factors other than occupational factors (industry and occupation) and obtained residual values. We computed the third quartile (Q3) of the residuals and then calculated the fractions exceeding the Q3 level for each combination of industry and occupation. RESULTS: Age, sex, body mass index, year, season, latitude, living area, living in an apartment, industry, and occupation were significantly associated with vitamin D levels. Based on the exceeding fraction, the armed forces showed the highest exceeding fraction level of 0.71. CONCLUSIONS: Our results present the high exposure groups to sunlight across industries and occupations. Our results may provide a source for prioritizing occupational groups with a high risk of adverse health effects from sunlight exposure.

Low insertion of cystic duct increases risk for common bile duct stone recurrence.

BACKGROUND: Common bile duct (CBD) stone is one of the most frequent biliary diseases. Recurrence after the complete removal of CBD stones is high, and we aim to evaluate the rate and risk factors for symptomatic recurrence of CBD stones after endoscopic retrograde cholangiopancreatography (ERCP). METHODS: We, retrospectively, reviewed the database of patients who underwent ERCP for CBD stones and subsequent cholecystectomy between January 2015 and December 2017 at a tertiary hospital. The recurrence of symptomatic CBD stones was defined as the presence of a CBD stone with related symptoms at least 6 months after the ERCP procedure. The primary outcomes were recurrence of symptomatic CBD stones and its risk factors. RESULTS: Among the 362 enrolled patients, 60 experienced a symptomatic recurrence of CBD stones between 6 months and 5 years after the procedure. The mean duration of follow-up was 32.3 ± 8.1 months. The patients with recurrences were older and had a longer follow-up duration. Low insertion of the cystic duct (HR = 2.893, p = 0.016), distal CBD angulation (HR = 1.015, p = 0.034), maximum CBD diameter (HR = 1.070, p = 0.012), number of ERCP sessions at first admission (HR = 1.558, p = 0.032), and cannulation time (HR = 1.030, p = 0.008) were the independent risk factors for symptomatic recurrent CBD stones. CONCLUSIONS: Patients with risk factors, especially those with low cystic duct insertion, are more prone to symptomatic recurrent CBD stones and should be followed more carefully.

Estimation of Lead Exposure Intensity by Industry Using Nationwide Exposure Databases in Korea.

BACKGROUND: In a previous study, we estimated exposure prevalence and the number of workers exposed to carcinogens by industry in Korea. The present study aimed to evaluate the optimal exposure intensity indicators of airborne lead exposure by comparing to blood lead measurements for the future development of the carcinogen exposure intensity database. METHODS: Data concerning airborne lead measurements and blood lead levels were collected from nationwide occupational exposure databases, compiled between 2015 and 2016. Summary statistics, including the arithmetic mean (AM), geometric mean (GM), and 95th percentile level (X95) were calculated by industry both for airborne lead and blood lead measurements. Since many measurements were below the limits of detection (LODs), the simple replacement with half of the LOD and maximum likelihood estimation (MLE) methods were used for statistical analysis. For examining the optimal exposure indicator of airborne lead exposure, blood lead levels were used as reference data for subsequent rank correlation analyses. RESULTS: A total of 19,637 airborne lead measurements and 32,848 blood lead measurements were used. In general, simple replacement showed a higher correlation than MLE. The results showed that AM and X95 using simple replacement could be used as optimal exposure intensity indicators, while X95 showed better correlations than AM in industries with 20 or more measurements. CONCLUSION: Our results showed that AM or X95 could be potential candidates for exposure intensity indicators in the Korean carcinogen exposure database. Especially, X95 is an optimal indicator where there are enough measurements to compute X95 values.