Recent advances in bronchoscopy have led to changes in clinical diagnostics and therapeutics in pulmonary medicine. In diagnostic bronchoscopy, there have also been new developments in endobronchial ultrasound technology which may be incorporated into clinical practice in the near future. Functional bronchoscopy, which evaluates information such as airway pressure, airflow, or gas exchange, suggests promising clinical advances in the near future. In therapeutic bronchoscopy, bronchoscopic volume reduction is a novel approach for the treatment of severe emphysema. In this review, seven recently published articles representing current advances in bronchoscopy are summarized and discussed.

Background: We investigated whether chrysin affected MUC5AC mucin production and gene expression induced by phorbol ester (phorbol 12-myristate 13-acetate, PMA) or epidermal growth factor (EGF) from human airway epithelial cells. Methods: Confluent NCI-H292 cells were pretreated with varying concentrations of chrysin for 30 minutes, and were then stimulated with PMA and EGF for 24 hours, respectively. MUC5AC mucin gene expression and mucin protein production were measured by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Results: Concentrations of $10{\mu}M$ and $100{\mu}M$ chrysin were found to inhibit the production of MUC5AC mucin protein induced by PMA; A concentration of $100{\mu}M$ chrysin also inhibited the production of MUC5AC mucin protein induced by EGF; $100{\mu}M$ chrysin inhibited the expression of MUC5AC mucin gene induced by PMA or EGF. The cytotoxicity of chrysin was checked by lactate dehydrogenase assay, and there was no cytotoxic effect observed for chrysin. Conclusion: These results suggest that chrysin can inhibit mucin gene expression and the production of mucin protein by directly acting on airway epithelial cells.

Background: The level of urine cotinine is an indicator of tobacco smoke exposure. The purpose of this study is to investigate urine cotinine for the purpose of assessing the smoking status of Korean smokers and non-smokers exposed to tobacco smoke. Methods: The subjects were identified from the 2007-2009 and the 2010 data sets of the Korea National Health and Nutrition Examination Survey (KNHANES). They were assigned as non-smokers, current smokers and ex-smokers. Non-smokers were also divided into three subset groups according to the duration of smoke exposure. Each group was stratified by gender prior to analysis. Results: The median value of urine cotinine in the male current smokers was 1,221.93 ng/mL which was the highest among all groups. The difference between levels of urine cotinine for male and the female groups was statistically significant (p<0.01). In the female group, passive smoke exposure groups reported higher urine cotinine levels than non-exposure groups (p=0.01). The cutoff point for the discrimination of current smokers from non-smokers was 95.6 ng/mL in males and 96.8 ng/mL in females. The sensitivity and specificity were 95.2% and 97.1%, respectively, in males, 96.1% and 96.5% in females. However, the determination of urine cotinine level was not useful in distinguishing between passive smoke exposure groups and non-exposure groups. Conclusion: Urine cotinine concentration is a useful biomarker for discriminating non-smokers from current smokers. However, careful interpretation is necessary for assessing passive smoke exposure by urine cotinine concentration.

Background: We investigated the prevalence of latent tuberculosis infection (LTBI) among medical students in South Korea. Methods: Students from one medical school, who were in second- or third-year classes before clerkship course, were enrolled for three consecutive years in the study. A standard questionnaire was given to each participant, and tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (QFT-GIT) assay, and chest radiography were performed. Results: A total of 153 participants were enrolled in the study. The mean age of the subjects was $21.9{\pm}0.9$ years, 105 (68.6%) were male, and 132 (86.3%) had been vaccinated with Bacille Calmette-Gu$\acute{e}$rin (BCG). Four students (2.6%) had a history of contact with tuberculosis (TB) patients during medical practice. No abnormal chest radiograph findings were found for any of the subjects. Of the 153 subjects, 23 (15.0%) tested positive for the TST, and 8 (5.2%) tested positive for the QFT-GIT. The agreement between the two tests was determined to be 0.34 using kappa coefficients. Of the four students who had a history of contact with TB patients, only one subject tested positive for both tests, and the other three students tested negative for both tests. Conclusion: A low prevalence of LTBI was found among medical students before clerkship course in South Korea.

Background: We evaluated the clinical outcomes and prognostic factors of patients requiring prolonged mechanical ventilation (PMV), defined as ventilator care for ${\geq}21$ days, who were admitted to the medical intensive care unit (ICU) of a university hospital in Korea. Methods: During the study period, a total of 2,644 patients were admitted to the medical ICU, and 136 patients (5.1%) were enrolled between 2005 and 2010. Results: The mean age of the patients was $61.3{\pm}14.5$ years, and 94 (69.1%) were male. The ICU and six-month cumulative mortality rates were 45.6 and 58.8%, respectively. There were 96 patients with tracheostomy placement after admission and their mean period from admission to the day of tracheostomy was $21.3{\pm}8.4$ days. Sixty-three patients (46.3%) were successfully weaned from ventilator care. Of the ICU survivors (n=74), 34 patients (45.9%) were transferred to other hospitals (not university hospitals). Two variables (thrombocytopenia [hazard ratio (HR), 1.964; 95% confidence interval (CI), 1.225~3.148; p=0.005] and the requirement for vasopressors [HR, 1.822; 95% CI, 1.111~2.986; p=0.017] on day 21) were found to be independent factors of survival on based on the Cox proportional hazard model. Conclusion: We found that patients requiring PMV had high six-month cumulative mortality rates, and that two clinical variables (measured on day 21), thrombocytopenia and requirement for vasopressors, may be associated with prognostic indicators.

Tadalafil is a phosphodiesterase-5 inhibitor (PDE5I), which is widely used to treat erectile dysfunction. Although PDE5Is have excellent safety profiles, and most of the side effects are mild, rare serious adverse events have been reported in association with PDE5Is. Thrombosis is one of those events, and a few previous reports have suggested the association of PDE5Is with thrombosis. We report the case of a 61-year-old male who developed pulmonary embolism combined with pulmonary infarction directly after taking tadalafil. Both the patient and the physician suspected tadalafil as the culprit drug, as the patient was in an otherwise healthy condition. However, after extensive evaluation, we noticed that factor VIII levels were elevated. Prior reports suggesting the association between thrombosis and PDEIs either lack complete information on coagulation factors, or show inconsistencies in their results. Physicians should operate caution prior to accepting the diagnosis of adverse drug reaction.

Recently, interferon gamma releasing assay has been recommended to compensate the tuberculin skin test (TST) for screening for latent tuberculosis infection (LTBI). Although it improved the detection of LTBI before treatment with tumor necrosis factor blocker, its application to immune suppressed patients is limited. We report a case of peritoneal tuberculosis (TB) developed in a patient who tested positive for TST and QuantiFERON-TB Gold (QFT-G) before infliximab therapy, to emphasize the importance of monitoring during treatment. A 52-year-old woman presented with abdominal distension. She had been diagnosed with seropositive rheumatoid arthritis six years ago. She had started taking infliximab six months ago. All screening tests for TB were performed and the results of all were negative. At admission, the results of repeated TST and QFT-G tests were positive. Histopathological examination confirmed peritoneal TB. The patient started anti-TB therapy and the symptoms were relieved.