Chulyong Park

Virulence attenuation of Streptococcus pneumoniae clpP mutant by sensitivity to oxidative stress in macrophages via an NO-mediated pathway

ClpP protease is essential for virulence and survival under stress conditions in several pathogenic bacteria. The clpP mutation in a murine infection model has demonstrated both attenuation of virulence and a sensitivity to hydrogen peroxide. However, the underlying mechanisms for these changes have not been resolved. Because macrophages play a major role in immune response and activated macrophages can kill microbes via oxygen-dependant mechanisms, we investigated the effect of the clpP mutation on its sensitivity to macrophage-mediated oxygen-dependant mechanisms. The clpP mutant derived from D39 (serotype 2) exhibited a higher sensitivity to oxidative stresses such as reactive oxygen intermediates, reactive nitrogen intermediates, and H2O2, but no sensitivity to osmotic stress (NaCl) and pH. Moreover, viability of the clpP mutant was significantly increased in murine macrophage cells by treatment with S-methylisothiourea sulfate, which inhibits inducible nitric oxide synthase (iNOS) activity and subsequently elicits lower level secretions of nitric oxide (NO). However, viability of wild type was unchanged. Taken together, these results indicate that ClpP is involved in the resistance to oxidative stresses after entrapment by macrophages and subsequently contributes to virulence via NO mediated pathway.

Prevalence of abortion and adverse pregnancy outcomes among working women in Korea: A cross-sectional study

[This corrects the article DOI: 10.1371/journal.pone.0182341.].

A Case of Tracheal Adenoid Cystic Carcinoma in a Worker Exposed to Rubber Fumes

BackgroundPrimary tracheal tumors occur infrequently, accounting for less than 0.1% of all tumors. Adenoid cystic carcinoma (ACC) is the second most common type of malignancy of the trachea after squamous cell carcinoma (SCC). Little has been reported on the risk factors for tracheal ACC. The purpose of this study is to describe a case of tracheal ACC in a patient who had been exposed to rubber fumes, and to review the relationship between tracheal ACC and rubber fumes.Case reportA 48-year-old man who had been experiencing aggravation of dyspnea for several months was diagnosed as having ACC of the trachea on the basis of a pathologic examination of a biopsy specimen obtained via laser microscopy-guided resection. The patient had been exposed to rubber fumes for 10 years at a tire manufacturing factory where he worked until ACC was diagnosed. His job involved preheating and changing rubber molds during the curing process.ConclusionACC of both the trachea and the salivary glands show very similar patterns with regard to histopathology and epidemiology and are therefore assumed to have a common etiology. Rubber manufacturing is an occupational risk factor for the development of salivary gland tumors. Further, rubber fumes have been reported to be mutagenic. The exposure level to rubber fumes during the curing process at the patient’s workplace was estimated to be close to or higher than British Occupational Exposure Limits. Therefore, tracheal ACC in this case might have been influenced by occupational exposure to rubber fumes.

Adverse pregnancy outcomes in healthcare workers: a Korean nationwide population-based study

PurposeTo assess female healthcare workers’ pregnancy complications and outcomes including abortion, fetal screening abnormalities, intrauterine growth retardation (IUGR), and preterm labor using nationwide population data and compare these results with those of the general population in Korea.MethodsKorean National Health Insurance (NHI) claim data was used. We choose 3 different reference groups for comparison: (1) dependents of employees insured by NHI, i.e. non-working women, (2) all insured employees, i.e. all working women, and (3) workers in the education division. To compare the groups, logistic regression was used for multivariate analysis after adjusting for age and income level.ResultsOverall, healthcare workers showed a higher adjusted OR (odds ratio) in almost all obstetrical consequences. Miscarriage, threatened abortion, preterm labor, fetal screening abnormalities, and IUGR showed a higher adjusted OR in the working group than in the non-working group. We also observed similar results in a comparison of both the working groups. Regarding workers in the education division, ORs for obstetrical outcomes were also high, except for preterm labor.ConclusionsHealth care workers have a higher risk of adverse pregnancy outcomes such as miscarriage, IUGR, and fetal screening abnormalities.

P279 A case of azoospermia in a non-destructive testing (NDT) worker exposed to ionising radiation

Many workers are exposed to ionising radiation and it has various detrimental health effects. Those are categorised into stochastic effects and deterministic effects. We represent a case of an azoospermic patient who exposed to ionising radiation and affected by deterministic effects for permanent infertility. He had been worked for a NDT company for six years and mainly performed the radiography testing (RT). He took RT images from 300 to 1,000 per day with barely equipped with protectives. After work, he felt nauseated, fatigue and got a headache from time to time. In addition, he could not conceive a baby even though he tried for eight years with normal intercourses and no contraceptives. He visited urology department and diagnosed with irreversible azoospermia and there were no evidence that he was congenitally infertile; He had a normal male genital organ, normal 46 XY male chromosomes without any microdeletion. While his thermo-luminescence dosimeter indicated his cumulative radiation dose were only 17.81 mSv for 80 months, the radiation dose evaluated by biological assessments was shown to be near two Grey (Gy); The dicentric chromosome assay showed 0.882 Gy (0.597–1.183, 95% CI) and the 1, 2, 4 translocation assay indicated 1.913 Gy (1.358–2.591, 95% CI). Based on the biological assessment of radiation, he was approved for work-relatedness by compensation committee of the Korea Workers Compensation and Welfare Service. In this case report, we represent a case of azoospermia caused by occupational exposure of ionising radiation and suggest biological assessments as an alternative evaluating index for whose radiation exposure is uncertain.

A case of chronic myeloid leukemia in a diagnostic radiographer

BackgroundOccupational radiation exposure causes certain types of cancer, specifically hematopoietic diseases like leukemia. In Korea, radiation exposure is monitored and recorded by law, and guidelines for compensation of radiation-related diseases were implemented in 2001. However, thus far, no occupation-related disease was approved for compensation under these guidelines. Here, we report the first case of radiation-related disease approved by the compensation committee of the Korea Workers’ Compensation and Welfare Service, based on the probability of causation.Case presentationA 45-year-old man complained of chronic fatigue and myalgia for several days. He was diagnosed with chronic myeloid leukemia. The patient was a diagnostic radiographer at a diagnostic radiation department and was exposed to ionizing radiation for 21 years before chronic myeloid leukemia was diagnosed. His job involved taking simple radiographs, computed tomography scans, and measuring bone marrow density.ConclusionTo our knowledge, this is the first approved case report using quantitative assessment of radiation. More approved cases are expected based on objective radiation exposure data and the probability of causation. We need to find a resolution to the ongoing demands for appropriate compensation and improvements to the environment at radiation workplaces.