Application of Testing-TracingTreatment Strategy in Response to the COVID-19 Outbreak in Seoul, Korea

Background@#Following the coronavirus disease 2019 (COVID-19) outbreak in Wuhan, China, a total of 637 patients had been diagnosed with the disease in Seoul as of May 2, 2020. Our study aimed to describe the impact of the 3T strategies (preemptive testing, prompt tracing and proper treatment) on the epidemiological characteristics of COVID-19 in Seoul. @*Methods@#The descriptive and explanatory analysis was carried out on critical indicators such as epidemiological characteristics and key duration of patient status change from January 24 to May 2 in Seoul before and after preemptive testing for patients under investigation associated with COVID-19 clusters. @*Results@#Preemptive testing increased the positive test rate (3.9% to 4.2%), an asymptomatic case at diagnosis (16.9% to 30.6%), and reduced the time from symptom onset to quarantine (4.0 to 3.0 days). Prompt tracing decreased unknown sources of infection (6.9% to 2.8%), the mean number of contacts (32.2 to 23.6), and the time-varying reproduction number R(t) (1.3 to 0.6). With proper treatment, only 2 cases of mortality occurred, resulting in a fatality rate of just 0.3%. @*Conclusion@#In the first wave of the COVID-19 pandemic lasting 100 days, the effect of the 3T strategies flattened the curve and decreased the time during which infected individuals were contagious, thereby lowering the R(t) below 1 in Seoul.

Association between employment status and sickness presenteeism among Korean employees:a cross-sectional study

Background@#Sickness presenteeism (SP) indicates “going to work while being ill.” The importance of SP has only recently been investigated, and the association between SP and employment status has been inconsistent across studies. Therefore, we conducted this study to explore the association between SP and employment status by using presenteeism propensity (PP), which can reflect the individual decision-making process. @*Methods@#The study population included employees participating in the 5th Korean Working Condition Survey. We analyzed data of only employees with at least one health event, which was calculated as the sum of SP and sickness absenteeism days. Employment status was grouped into 3 categories: stable employment, unstable employment (contract period ≥ 1 year), and unstable employment (contract period 0.5”). @*Results@#Unstable employees (contract period ≥ 1 year) had higher odds of PP than stable employees (odds ratio [OR]: 1.23, 95% confidence interval [CI]: 1.03–1.47), whereas unstable employees (contract period < 1 year) had lower odds of PP than stable employees (OR: 0.82, 95% CI: 0.71–0.96). @*Conclusions@#Employment status was associated with SP. Given the negative health impact of SP, social efforts, such as paid sick leave, are required to reduce SP and enhance the health status of unstable workers.

Association between employment status and sickness presenteeism among Korean employees:a cross-sectional study

Background@#Sickness presenteeism (SP) indicates “going to work while being ill.” The importance of SP has only recently been investigated, and the association between SP and employment status has been inconsistent across studies. Therefore, we conducted this study to explore the association between SP and employment status by using presenteeism propensity (PP), which can reflect the individual decision-making process. @*Methods@#The study population included employees participating in the 5th Korean Working Condition Survey. We analyzed data of only employees with at least one health event, which was calculated as the sum of SP and sickness absenteeism days. Employment status was grouped into 3 categories: stable employment, unstable employment (contract period ≥ 1 year), and unstable employment (contract period 0.5”). @*Results@#Unstable employees (contract period ≥ 1 year) had higher odds of PP than stable employees (odds ratio [OR]: 1.23, 95% confidence interval [CI]: 1.03–1.47), whereas unstable employees (contract period < 1 year) had lower odds of PP than stable employees (OR: 0.82, 95% CI: 0.71–0.96). @*Conclusions@#Employment status was associated with SP. Given the negative health impact of SP, social efforts, such as paid sick leave, are required to reduce SP and enhance the health status of unstable workers.

A study of relationship between blood mercury concentration and hypertension in residents living in old mine fields and related factors

BACKGROUND: In Korea, around the abandoned metal mines, heavy metals are being accumulating in the cultivated areas. Among exposed heavy metals, mercury is known to harm for cardiovascular system known to affect blood pressure. So, we studied the relationship between blood mercury level and hypertension in residents around abandoned metal mines. METHODS: From 2008 to 2011, we surveyed 7,055 residents in provinces affected by abandoned metal mines and collected data from 6 Hospitals. We conducted a personal questionnaire interview survey with residents on the basis of household questionnaires, sex, age, household income, smoking, and drinking items. Multiple logistic regression analysis was performed to investigate the association between blood mercury level and hypertension. RESULTS: We compared residents with low and high groups based on blood mercury level 5.8 μg/L, and higher group was significantly higher risk of hypertension than lower group (odds ratio [OR]: 1.277; 95% confidence interval [CI]: 1.135–1.436), also in adjusted model, higher group was significantly higher risk of hypertension than lower group (OR: 1.276; 95% CI: 1.117–1.457). CONCLUSIONS: This study showed a significant correlation between mercury and hypertension in residents around abandoned metal mines. Therefore, we should continuously monitor people who are higher than the standard value and the hypertensive patients.

A cross-sectional study on the pulmonary function of residents in two urban areas with different PM10 concentrations: data from the fourth Korea national health and nutrition examination survey (KNHANES) 2007–2009

BACKGROUND: The present study aims to compare the pulmonary function of residents of Seoul special city (Seoul) and Jeju special self-governing province including Jeju city and Seogwipo city (Jeju), characterized by vastly different annual average airborne particulate matter with an aerodynamic diameter less ≤10 μm (PM10) concentrations, with the annual average PM10 concentration in Seoul being significantly higher than that in Jeju. METHODS: This cross-sectional study analyzed the pulmonary function test results and sociodemographic data of Korean adults ≥19 years of age derived from the 4th KNHANES, 2007–2009. A total of 830 individuals residing in Seoul or Jeju were included in this study. T-tests were used to analyze predicted values of forced expiratory volume in 1 sec (FEV1p), predicted values of forced vital capacity (FVCp) and FEV1/FVC ratio (FEV1/FVC), as dependent variables, to examine the differences in the subjects’ pulmonary function according to the city of residence. Stratified analysis was then performed to adjust for variables potentially affecting pulmonary function. The analysis was performed on subjects as a group and also following stratification according to sex and other variables. RESULTS: Seoul residents had a significantly lower FVCp than that of the Jeju residents (difference: 3.48%, p = 0.002). FEV1p, FVCp and FEV1/FVC of male Seoul residents were significantly lower than those of male Jeju residents (difference: 6.99, 5.11% and 0.03, respectively; p < 0.001, p = 0.001, p = 0.001). In male subjects, statistically significant results were obtained even after adjusting the influence of other variables through stratified analysis. CONCLUSION: The present analysis was based on cross-sectional data collected at one point in time. Therefore, unlike longitudinal studies, it does not establish a clear causal association between the variables. Nevertheless, this study found that pulmonary function among subjects residing in Seoul was significantly decreased compared to that of subjects residing in Jeju.

Hydroquinone suppresses IFN-β expression by targeting AKT/IRF3 pathway

Previous studies have demonstrated the role of hydroquinone (HQ), a hydroxylated benzene metabolite, in modulating various immune responses; however, its role in macrophage-mediated inflammatory responses is not fully understood. In this study, the role of HQ in inflammatory responses and the underlying molecular mechanism were explored in macrophages. HQ down-regulated the expression of interferon (IFN)-β mRNA in LPS-stimulated RAW264.7 cells without any cytotoxicity and suppressed interferon regulatory factor (IRF)-3-mediated luciferase activity induced by TIR-domain-containing adapter-inducing interferon-β (TRIF) and TANK-binding kinase 1 (TBK1). A mechanism study revealed that HQ inhibited IRF-3 phosphorylation induced by lipopolysaccharide (LPS), TRIF, and AKT by suppressing phosphorylation of AKT, an upstream kinase of the IRF-3 signaling pathway. IRF-3 phosphorylation is highly induced by wild-type AKT and poorly induced by an AKT mutant, AKT C310A, which is mutated at an inhibitory target site of HQ. We also showed that HQ inhibited IRF-3 phosphorylation by targeting all three AKT isoforms (AKT1, AKT2, and AKT3) in RAW264.7 cells and suppressed IRF-3-mediated luciferase activities induced by AKT in HEK293 cells. Taken together, these results strongly suggest that HQ inhibits the production of a type I IFN, IFN-β, by targeting AKTs in the IRF-3 signaling pathway during macrophage-mediated inflammation.

Association between supervisors' behavior and wage workers' job stress in Korea: analysis of the fourth Korean working conditions survey

BACKGROUND: In modern society, many workers are stressed. Supervisors' support or behavior can affect the emotional or psychological part of the worker. The purpose of this study is to investigate the effect of supervisor's behavior on worker's stress. METHODS: The study included 19,272 subjects following the assignment of weighted values to workers other than soldiers using data from the Fourth Korean Working Condition Survey. Supervisors' behavior was measured using 5 items: “supervisor feedback regarding work,”“respectful attitude,”“good conflict-resolution ability,”“good work-related planning and organizational ability,” and the encouragement of participation in important decision making. Job stress was measured using 1 item: “I experience stress at work.” Multiple logistic regression analysis was performed to examine the effects of supervisors' behavioral, general, occupational, and psychosocial characteristics on job stress in workers. Organizational characteristics associated with supervisors' behavior were also analyzed. RESULTS: The results showed that supervisors' provision of feedback regarding work increased workers' job stress (OR = 1.329, 95% CI = 1.203 ~ 1.468). When a supervisor respect workers (OR = 0.812, 95% CI = 0.722 ~ 0.913) or good at planning and organizing works (OR = 0.816, 95% CI: 0.732 ~ 0.910), workers' job stress decreased. In particular, the two types of supervisor behaviors, other than feedback regarding work, were high in private-sector organizations employing less than 300 employees. CONCLUSION: Supervisors' behavior influenced job stress levels in workers. Therefore, it is necessary to increase education regarding the effects of supervisors' behavior on job stress, which should initially be provided in private-sector organizations with up to 300 employees.

Relationship of workplace violence and perpetrators on sleep disturbance-data from the 4th Korean working conditions survey

OBJECTIVE: The present study analyzed relationship of workplace violence and perpetrators of violence on sleep disturbance among wage workers in Korea. METHODS: The present study used data from the 4th Korean Working Conditions Survey (KWCS) of 2014 in selecting a total of 25,138wage workers as the study population, which excluded those who failed or refused to respond to questions required for the present study. The workplace violence experience group included people who satisfied at least one of six relevant criteria (verbal abuse, unwanted sexual attention, threatening or humiliating behavior, physical violence, bullying/harassment, and sexual harassment) and the group was divided according to whether the perpetrator of violence was a client or colleague. Presence of sleep disturbance was determined based on subjective symptoms felt within the past 12 months by each individual. A multiple logistic regression analysis was performed to identify the effects on sleep distance according to general, occupational, and psychosocial characteristics, as well as the types of workplace violence and perpetrators of violence. RESULTS: Workplace violence was found as a factor affecting sleep disturbance (OR = 3.773, 95 % CI = 3.058–4.655), and with respect to perpetrators of violence, complaint of sleep disturbance symptoms was higher when the perpetrator was a colleague or boss (OR = 5.688, 95 % CI 4.189–7.723) than a client (OR = 2.992, 95 % CI 2.301–3.890). CONCLUSION: Workplace violence had an effect on occurrence of sleep disturbance and when the perpetrators of violence was a boss or colleague at work, the risk for symptoms such as sleep disturbance increased, which indicated the need for appropriate intervention from a workplace healthcare perspective, including preventive education of workplace violence among employees.

Association between shift work and obesity according to body fat percentage in Korean wage workers: data from the fourth and the fifth Korea National Health and Nutrition Examination Survey (KNHANES 2008-2011)

BACKGROUND: Health problems in shift workers vary including obesity acting as a risk factor in cerebrovascular diseases. Recent studies have commonly determined the prevalence of obesity in shift workers on the basis of body mass index. The accuracy of BMI for diagnosing obesity are still limited apparently. Consequently, this study aimed to determine the relationship between shift work and obesity according to the total body fat percentage in Korean wage workers. METHODS: From the Fourth and the Fifth Korea National Health and Nutrition Examination Survey (2008-2011), after military personnel were excluded, a total of 2952 wage workers (20 or =25.7 % in males and > or =36.0 % in females). The subjects were divided into groups by gender and work type (manual vs non-manual), and chi-squared test was used to evaluate the relationship between socio-economic, health behavior, and work-related factors, on the one hand, and obesity, on the other. In addition, multivariate logistic regression analysis was performed to examine the effects of shift work on obesity. RESULTS: When other factors were controlled for, the risk of obesity in shift work showed a statistically significant increase (odds ratio = 1.779, 95 % confidence interval = 1.050-3.015) in the male manual worker group. However, there were no significant results in the male non-manual and female worker groups. CONCLUSION: Shift work was related to a higher risk of obesity in the Korean male manual worker group.

Efficacy of Lateral Canthoplasty Combined with Transconjuctival Lower Blepharoplasty in Young Asian Patients

BACKGROUND: The lower eyelid bag associated with an old and tired appearance is not a rare aesthetic problem in young Asian people who have short palpebral fissures and an up-slanting appearance. Many patients want to make their eyes larger, brighter and more youthful at the same time. The purpose of the current study was to determine the feasibility of lateral canthoplasty combined with transconjunctival lower blepharoplasty in minimizing complications and maximizing aesthetic results. METHODS: From June 2011 to May 2014, 59 patients underwent inferior orbital fat removal and orbital septal resets through transconjunctival approaches and lateral canthoplasty. Simple inferolateral canthotomy incisions were used to provide a sufficient operative field for manipulation of the orbital septum, to lengthen the horizontal palpebral fissures and to lower the lateral canthal angle. Patients were evaluated to identify the presence of postoperative complications and to assess the need for additional operations. RESULTS: Most of the patients were satisfied with the aesthetic results during the 2-12-month postoperative follow-up period. There were no recurrences of lower eyelid bulging, postoperative asymmetry, or wound-related complications. Three cases of entropion and two cases of roundness of the lateral canthal angle occurred following the primary operation. However, there were no further complications after secondary operations to correct the tarsal-periosteal fixation position. CONCLUSIONS: Lateral canthoplasty combined with transconjunctival lower blepharoplasty using simple lateral canthotomy is a safe and effective method for maximizing aesthetic results in young Asian patients.

A Case of Complicated Silicosis with a Complex Clinical Course in a Glass Manufacturing Worker

We reported a case of complicated silicosis that occurred in a glass manufacturing plant worker who had presumably been exposed to low-concentration free silica for almost 20 years. To the best of our knowledge this report is the first in the Republic of Korea. The physician's first impression was cancer since the enlargement of neck and supraclavicuar lymph nodes had clearly progressed and metastasis was suspected in ultrasonography. However, it turned out to be reactive hyperplasia and anthracosis. Although lung cancer was suspected and tests were performed in 2 hospitals due to repetitive cough and dyspnea, along with weight loss of approximately 10% over the course of 7 months, the patient was eventually diagnosed with complicated silicosis and pneumothorax occurred after 1 year. Herein, we report this case with a literature review.

Cementless Total Hip Arthroplasty for Patients with Crowe Type III or IV Developmental Dysplasia of the Hip: Two-Stage Total Hip Arthroplasty Following Skeletal Traction after Soft Tissue Release for Irreducible Hips

BACKGROUND: Total hip arthroplasty (THA) for severe developmental dysplasia of the hip (DDH) is a technically demanding procedure for arthroplasty surgeons, and it is often difficult to reduce the hip joint without soft tissue release due to severe flexion contracture. We performed two-stage THAs in irreducible hips with expected lengthening of the affected limb after THA of over 2.5 cm or with flexion contractures of greater than 30 degrees in order to place the acetabular cup in the true acetabulum and to prevent neurologic deficits associated with acute elongation of the limb. The purpose of this study is to evaluate the outcomes of cementless THA in patients with severe DDH with a special focus on the results of two-stage THA. METHODS: Retrospective clinical and radiological evaluations were done on 17 patients with Crowe type III or IV developmental DDH treated by THA. There were 14 women and 3 men with a mean age of 52.3 years. Follow-ups averaged 52 months. Six cases were treated with two-stage THA followed by surgical hip liberalization and skeletal traction for 2 weeks. RESULTS: The mean Harris hip score improved from 40.9 to 89.1, and mean leg length discrepancy (LLD) in 13 unilateral cases was reduced from 2.95 to 0.8 cm. In the patients who underwent two-stage surgery, no nerve palsy was observed, and the single one-stage patient with incomplete peroneal nerve palsy recovered fully 4 weeks postoperatively. CONCLUSIONS: The short-term clinical and radiographic outcomes of primary cementless THA for patients with Crowe type III or IV DDH were encouraging. Two-stage THA followed by skeletal traction after soft tissue release could provide alternative solutions to the minimization of limb shortenings or LLD without neurologic deficits in highly selected patients.

Malignant Fibrous Histiocytoma of the Maxillary Sinus in a Spray Painter from an Automobile Repair Shop

BACKGROUND: We report a case of a spray painter who developed malignant fibrous histiocytoma (MFH) of the maxillary sinus following long-term exposure to chromium, nickel, and formaldehyde, implying that these agents are probable causal agents of MFH. CASE REPORT: The patient developed right-sided prosopalgia that began twenty months ago. The symptom persisted despite medical treatment. After two months, he was diagnosed with MFH through imaging studies, surgery, and pathological microscopic findings at a university hospital in Seoul. His social, medical, and family history was unremarkable. The patient had worked for about 18 years at an automobile repair shop as a spray painter. During this period, he had been exposed to various occupational agents, such as hexavalent chromium, nickel, and formaldehyde, without appropriate personal protective equipment. He painted 6 days a week and worked for about 8 hours a day. Investigation of the patient's work environment detected hexavalent chromium, chromate, nickel, and formaldehyde. CONCLUSIONS: The study revealed that the patient had been exposed to hexavalent chromium, formaldehyde, and nickel compounds through sanding and spray painting. The association between paranasal cancer and exposure to the aforementioned occupational human carcinogens has been established. We suggest, in this case, the possibility that the paint spraying acted as a causal agent for paranasal cancer.

Lung Function in Workers at Small Foundries / 대한산업의학회지

OBJECTIVES: This study investigated lung function in workers exposed to dusts, fumes and noxious gases at small foundries. METHODS: Lung function was measured in 148 male workers from 12 small foundries and 202 unexposed male workers. Pulmonary function tests performed included: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), percent of FEV1/FVC (FEV1/FVC%), maximum mid-expiratory flow (MMEF), peak expiratory flow (PEF), and forced expiratory flow at 25, 50, and 75% of expired FVC (FEF25, 50, 75). RESULTS: Mean values of all ventilatory indices except FEF25 of foundry workers were significantly lower than those of controls. Specifically, following stratification by smoking habits, all ventilatory indices except FEF25 of foundry workers were significantly lower than those of controls who smoked; however, there were no significant differences observed in any ventilatory indices between nonsmoking exposed workers and controls. The results of multiple linear regression analysis indicated work duration as a significant predictor of a decrease in FVC%. CONCLUSIONS: This research indicates that combined occupational exposure to dust, fumes, and gases in small foundries is associated with a reduction in lung function. Smoking may also contribute to respiratory abnormalities. These results suggested that foundry workers should be required to undergo periodic lung function tests and-in addition to not smoking, efficient use of personal protection equipment while at work is recommended.

The Result and Attentiveness of Reconstructive Surgery by Anterolateral Thigh Perforator Free Flap

PURPOSE: Anterolateral thigh(ALT) perforator free flap is commonly used because of its various benefits. The author reports important factors of preoperative and perioperative ALT perforator free flap and causes of failure. METHODS: 84 patients who were treated with ALT perforator free flap from December 2004 to 2008, and February 2010 to April 2010 were studied. 61 patients were male and 23 were female. The mean age of patients was 51.1. The main cause was neoplasm and the main reconstructive areas were head and neck area. The size of flap was various from 3 x 4 to 12 x 18cm. 6 patients received split thickness skin graft at donor site. Preoperative angiography was checked to all patients. RESULTS: Among the 84 patients, partial necrosis of flaps occurred in 4 patients because of atherosclerosis, varicose vein, or inattention of patient, etc. And total flap necrosis in 5 patients because of abnormal vessels of recipient area or delay of operation, etc. One case of serous cyst was found as the complication of donor area. Two cases of skin graft on donor site were done because of suspected muscle compartment syndrome, 4 cases of that because of large flap. Septocutaneous perforators were found in 7 cases. The author couldn't find reliable perforator in 3 cases, ipsilateral anteromedial thigh perforator and contralateral ALT perforator and latissimus dorsi musculocutaneous free flap were done instead of ALT. There was no case which needed reoperation because of the impairment of blood supply, and 3 cases were revised by leech because of the burn injury by a lamp or venous congestion. CONCLUSION: Although ALT perforator free flap is widely used with its various merits, many factors such as preoperative condition of donor or recipient area, morphology of defect and operating time need to consider to prevent flap necrosis. And operators should need careful technique because septocutaneous perforator is uncommon, and musculocutaneous perforator is common but difficult to dissect.

Enhancement of Vasculogenesis and Osteogenesis Using Granulocyte-Colony Stimulating Factor in the Rat Model of Tibial Distraction Osteogenesis / 대한정형외과학회잡지

PURPOSE: Proper speed of distraction is critical for successful new bone formation in distraction osteogenesis. The purpose of this study was to evaluate the effect of granulocyte-colony stimulating factor (G-CSF) on formation of new blood vessels and new bones in the rat model of tibial distraction osteogenesis (DO) to develop enhancement method of bone formation while increasing the distraction speed. MATERIALS AND METHODS: Forty two rat-tibial DO models were included in this study, and were divided into 3 groups; group I (rapid distraction), group II (rapid distraction with G-CSF), and group III (slow distraction). The amount of bone formation and relative blood flow were analyzed by sequential radiographs and laser Doppler perfusion imaging (LDPI). Blood sampling was done before G-CSF injection, at 2 weeks and 5 weeks after G-CSF injection and surface expression such as Scal-1+ and C-kit+ of endothelial progenitor cells (EPCs) was analyzed by fluorescence-activated cell sorter (FACS) for the effects of G-CSF in inducing mobilization of EPCs. RESULTS: The amount of new bone formation in the distraction gap on serial radiographs was higher during the consolidation period in groups II and III than in group I but, the difference was not significant (p>0.05). The relative blood flow in the distraction gap in groups II and III increased more significantly than in group I (p<0.05). FACS analysis showed an increased EPCs fraction after G-CSF injection. CONCLUSION: We demonstrated that G-CSF administration ameliorated bone formation and blood flow during rapid distraction in the rat model of tibial distraction osteogenesis. We think that G-CSF has an effect on mobilization of EPCs resulting in an increase in the blood flow.

Absence of Hyper-Responsiveness to Methacholine after Specific Bronchial Provocation Tests in a Worker With Hydroxyapatite-Induced Occupational Asthma

Hydroxyapatite is commonly used as a filler to replace amputated bone or as a coating to promote bone ingrowth into prosthetic implants. Many modern implants, such as hip replacements and dental implants, are coated with hydroxyapatite. We report a patient with occupational asthma due to hydroxyapatite, proven by a specific inhalation challenge, who experienced an early asthmatic reaction after exposure to hydroxyapatite, without increased airway responsiveness to methacholine despite an increased eosinophil count in the peripheral blood. A 38-year-old male dental implant worker visited our allergy department for the evaluation of occupational asthma. He had treated dental implant titanium surfaces with hydroxyapatite for 1.5 years. One year after starting his employment, he noticed symptoms of rhinorrhea, paroxysmal cough, and chest tightness. His symptoms were aggravated during and shortly after work and subsided several hours after work. When he stopped working for 2 months because of his chest symptoms, he became asymptomatic. After restarting his work, his symptoms reappeared and were aggravated. A methacholine bronchial challenge test had a negative response. The following day, a specific bronchial provocation test with wheat powder was negative. On the third day, a specific bronchial provocation test with hydroxyapatite powder produced an early asthmatic response. On the fourth day, a methacholine bronchial challenge test was negative. Further studies are needed to evaluate the exact pathogenetic mechanism of hydroxyapatite-induced occupational asthma.

Occupational Lung Cancer Surveillance in South Korea, 2006-2009

OBJECTIVES: The lung cancer mortality in Korea has increased remarkably during the last 20 years, and has been the first leading cause of cancer-related deaths since 2000. The aim of the current study was to examine the time trends of occupational lung cancer and carcinogens exposure during the period 2006-2009 in South Korea, by assessing the proportion of occupational burden. METHODS: We defined occupational lung cancer for surveillance, and developed a reporting protocol and reporting website for the surveillance of occupational lung cancer. The study patients were chosen from 9 participating university hospitals in the following 7 areas: Seoul, Incheon, Wonju, Daejeon, Daegu, Busan, and Gwangju. RESULTS: The combined proportion of definite and probable occupational lung cancer among all lung cancers investigated in this study was 10.0%, 8.6%, 10.7%, and 15.8% in the years 2006 to 2009, respectively, with an average of 11.7% over the four-year study period. The main carcinogens were asbestos, crystalline silica, radon, polyaromatic hydrocarbons (PAHs), diesel exhaust particles, chromium, and nickel. CONCLUSION: We estimated that about 11.7% of the incident lung cancer was preventable. This reveals the potential to considerably reduce lung cancer by intervention in occupational fields.

The Brain Pathology on Recovery of Brain MRI after Manganese Administration in Rats / 대한산업의학회지

OBJECTIVES: This study was carried out to investigate the effect on manganese on the brain of Sprague-Dawley rats, with particular focus on changes to anatomical pathology when brain MRI was recovered after manganese administration. METHODS: There were 15 rats divided into 3 groups of 5 based on dose of manganese: control group, low dose group (10 mg/kg), and high dose group (40 mg/kg). Each dosing group received an injection of normal saline and manganese via the tail vein once a week for 4 weeks. And then, the rats were observed for 12 weeks after stopping manganese administration. Next, each rat underwent a brain MRI and then each was sacrificed. After the rats were killed, the concentrations of blood manganese were measured, and pathologic examinations of the brain were performed. RESULTS: The signal intensity of basal ganglia on T1-weighted imaging of brain MRI did not differ between dosing groups. However, the ratio of neuron/glial cell in the basal ganglia was decreased in the low- and high-dose groups compared to the control group. CONCLUSIONS: This study showed that the damage of neuron in basal ganglia might be permanent after signal intensity of basal ganglia on T1-weighted imaging of brain MRI was recovered.

The Change of Brain MRI and Pathology According to the Administered Dose of Manganese in Rats / 대한산업의학회지

OBJECTIVES: This study was carried out to investigate the effect of manganese on the brains of rats, and chronic exposure to manganese is known to induce Parkinsonism in human. METHODS: The rats were divided into three groups: the first group was a control group that was administrated normal saline, and the second group was subdivided into the low dose group (10 mg/kg) and the high dose group (40 mg/kg) according to the administered dose of manganese. The rats of each group received an injection of normal saline and manganese via a tail vein once a week for 4 weeks. The rats were sacraficed at 4 weeks after the first adminstration of manganese. Brain MR imaging was performed before the rats were killed. After the rats were killed, the concentration of blood manganese was measured, and pathologic examination of the brain was performed in all the groups. RESULTS: The concentration of blood manganese was increased proportionally to the administered dose. The signal intensity of the basal ganglia on the T1-weighted imaging of brain MRI was increased in accordance with the administered dose. The ratio of neuron/glial cells in the basal ganglia was decreased in the experiment group as compared to that of the control group. CONCLUSIONS: This study showed that the signal intensity and the damage of neurons in basal ganglia were increased according to the administered dose of manganese in rats.