• Sleep Medicine and Psychophysiology
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• v.20 no.2
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• pp.69-74
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• 2013

Introduction: Although it is well known that medical students are not getting an adequate amount of sleep, there have been only a few studies on the sleep patterns of medical students and the related factors. Therefore, the present study aimed to investigate the medical students' sleep patterns and the related factors. Methods: A questionnaire package was administered to the $1^{st}$ to $4^{th}$ year medical students at one medical school. It consisted of questions asking about their lifestyles as well as Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), global assessment of recent stress scale (GASS), the center for epidemiologic studies-depression scale (CES-D), and Moudsley obsessive-compulsive inventory (MOCI). A total of 352 students (206 males and 146 females) responded to the survey and the result was analyzed using the independent t-test, the chi-square test, the paired t-test, Pearson's correlation and ANOVA. p-values of less than 0.05 were considered statistically significant in analyses. Results: The weekend bedtime was significantly delayed (0 : 49 on weekday ; 1 : 34 on weekend ; t=-5.23, p<0.001), the weekend rise time was delayed (6 : 58 on weekday ; 9 : 30 on weekend ; t=-24.48, p<0.001) and the total sleep time was increased on weekends (5 : 36 on weekday ; 7 : 39 on weekend ; t=15.94, p<0.001). The PSQI score of all subjects was 6.43{\pm}2.64. PSQI was positively correlated with ESS (r=0.383, p<0.001), GASS (r=0.326, p<0.001), CES-D (r=0.393, p< 0.001), and MOCI (r=0.247, p<0.001), but not with GPA (r=0.072, p=0.228. The more senior students had lower PSQI, GASS, CES-D, and MOCI score (p<0.05). Conclusion: Medical students were experiencing a lack of sleep during weekdays as they have a later bedtime and earlier rise time, and consequently had more hours of sleep on weekends. Overall, the medical students were experiencing poor sleep quality and sleep deprivation. Poor sleep quality is associated with psychological problems (daytime sleepiness, stress, depression, and obsessive tendency).

• Tuberculosis and Respiratory Diseases
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• v.48 no.3
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• pp.331-338
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• 2000

Background : While the incidence of lung cancer is gradually leveling off in developed countries, it is continuing to rise in Korea. With the rapid increase in the prevalence of smoking among women and the young, the incidence of lung cancer is also expected to increase within the next three and four decades. The aims of the present study are to analyze the smoking habits in patients with lung cancer and to evaluate of the relative risk of lung cancer according to patients' smoking habits. Method : This investigation was a hospital-based, case control study, which included data of 93 case subjects with lung cancer and 1132 controls with disease unrelated to smoking, obtained through a smoking history questionnaire by a direct personal interview. Result : Compared with non-smokers, those who smoked for more than 50 years had an odds ratio for lung cancer of 8.8(1.8-20.7). The odds ratios was 8.5(3.5-20.7) for those who smoke more than a total of 40 cigarettes per day and 5.5(2.3-13.3) for men who started habitual smoking under the age of 20. The risk increased for men with more than of cigarette smoking(OR : 5.5, 95% CIa : 2.6-11.9). Odds ratios associated with cigarette smoking were 2.5(1.1-5.8) and 5.1(2.6-10.4) for ex-smokers and current smokers, respectively and 2.2(0.0-4.6) for non-filter smokers of more than 16 years. Conclusion : There was a clear dose-response relationship between the risk of lung cancer and smoking. It can be concluded that dose is an important risk factor for lung cancer, as well as smoking habits.

• Tuberculosis and Respiratory Diseases
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• v.51 no.5
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• pp.437-447
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• 2001

Background: TNF-alpha is related to the generation of lung fibrosis in patients with UIP. The precise mechanism leading to lung fibrosis by TNF-alpha is unknown. However, the activation of a transcription factor like AP-1(down stream of c-jun N-terminal kinase, JNK) by TNF-alpha may be related to the induction of fibrogenic cytokines like PDGF or IGF-I. Furthermore, JNK was reported to be activated in the radiation-induced lung fibrosis model. This study examined JNK activity in patients with UIP. Methods : The expression of phosphorous JNK(p-JNK), macrophage/monocyte specific markers, CD68, and cytokeratin was evaluated by immunohistochemical(IHC) staining of lung tissues from patients with UIP and lung cancer. An in vitro kinase assay was performed with alveolar macrophages obtained by a bronchol-avleolar lavage from patients with UIP and healthy persons as the control. Results : The IHC stain showed that p-JNK is expressed in the almost all of the alveolar macrophages and smooth muscle cells in patients with UIP. In case of the normal areas of the lung from patients with lung cancer, the alveolar macrophages showed little p-JNK expression. Interestingly, increased JNK activity was not found in the in vitro kinase assay of the alveolar macrophages obtained from both patients with UIP and healthy persons as the control. Furthermore, 10 ng/mL of TNF-alpha failed to increase the JNK activity of the alveolar macrophages in both patients with UIP and healthy people. Conclusion : The JNK was activated constitutionally in patients with UIP. However, the role of JNK in the pathogenesis of lung fibrosis needs to be clarified.

• Tuberculosis and Respiratory Diseases
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• v.51 no.5
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• pp.426-436
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• 2001

Objective : This study was performed to determine the smoking status and its associated factors in military life among young Korean men to provide data for smoking prevention in military areas as a part of the health promotion program for soldiers. Methods : 1,033 infantrymen serving in 17 military units, which are located in suburbs of K city, were enrolled in this study. A questionnaire on the soldiers smoking status and other various characteristics was obtained from October 2nd to 12th, 2000. Logistic regression analysis was performed on the various variables in order to determine the factors related to smoking. Results : 1) 830(80.3%) out of 1033 subjects had smoked cigarettes and 759 persons(73.4%) were regular smokers. 2) Among the 734 soldiers who started smoking before their military service, 714 soldiers(97.2%) continued to smoke after, while 45 soldiers(15.0%) among the 299 non-smokers started smoking after joining the army. 3) Through the logistic regression analysis. the education level. specialty in the army. smoking amongst the friends they met before military service, smoking amongst soldiers in the army. dating girl friends, drinking, satisfaction with their army lives and the presence of convenient smoking places at the barracks were significant factors related to the prevalence of smoking in soldiers. Conclusion : The factors related with incidence of smoking in the army are the complicated interactions among the individuals personal background, general characteristics of the soldier and the special environment in the barracks. Therefore, to improve national soldiers' health, an active non-smoking campaign and education should be pushed to discourage smoking in the barracks.

• Tuberculosis and Respiratory Diseases
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• v.50 no.4
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• pp.473-483
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• 2001

Background : There are only a few studies regarding the causes of treatment failure for tuberculosis. Therefore, this study aimed to determine the causes of intractable tuberculosis. Methods : M. tuberculosis, differentiated MOTT (Mycobacterium Other Than Tuberculosis) were isolated, and the RFLP (Restriction fragments length polymorphisms) pattern was analyzed from 204 patients with pulmonary tuberculosis and 53 suffering from neck tuberculosis. The IL-$1{\beta}$, IL-12, $^*1\;IFN{\gamma}$ and $^*2\;TNF{\alpha}$ blood levels were measured. All patients were regularly followed for 18 months after treatment. Results : There was no correlation between the RFLP patterns of M. tuberculosis treatment failure. From the 204 cases, 31.9% were intractable. The characteristics of patients with intractable tuberculosis were old age, being male and recurrent cases. The causes of treatment failure were identified as follows ; a decrease in the IL-12(59.4%) concentration, drug resistant strain(54.7%), irregular medication(15.4%), MOTT(6.2%) and a heavy infection(4.6%). The causes of all cases of intractable tuberculosis could be investigated. The IL-12 concentration in the blood was significantly lower in the intractable cases, where it disclosed a maximum sensitivity(64.7%) and specificity(75.4%) at 165.0 pg/mL. Most of the 53 cases of neck node tuberculosis were treated successfully. Therefore, we were unable to analyze the cause of treatment failure. Conclusion : A decrease in the blood IL-12 concentration and drug resistant strains were identified as the most significant causes of treatment failure for tuberculosis. In Korea, infection by clusters were prevalent, but no difference in the clinical course between clusters and non-clusters could be found.

• Tuberculosis and Respiratory Diseases
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• v.43 no.5
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• pp.720-727
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• 1996

Objectives: $^{201}TI$ - chloride, $^{99m}Tc$ - MIBI, $^{99m}Tc$(V) - DMSA SPECT has been used in distinguishing lung cancer from benign lesion. To compare the diagnostic efficacy of SPECT with these tumor - seeking agents, we perfonned three consecutive SPECT using $^{201}TI$, $^{99m}Tc$ - MIBI, $^{99m}Tc$(V) - DMSA in same subjects with a solitary pulmonary lesion. Methods: SPECT was carried out at 10min and 3hr for $^{201}TI$ after injection of 20mCi, and 2hr for $^{99m}Tc$ - MIBI and $^{99m}Tc$(V) - DMSA after injection of 20mCi, respectively, in 37 patients with a solitary pulmonary lesion(27 lung cancer and 10 benign diseases). In patients showing visual uptake on lesion site, we obtained the lesion - to - background(target lesion/contralateral normal lung) uptake ratio from transverse slice for each radionuclide and also calculated the retention index for $^{201}TI$. Results: The diagnostic sensitivity of $^{201}TI$, $^{99m}Tc$ - MIBI and $^{99m}Tc$(V) - DMSA SPECT to lung cancer was 100%, 96% and 73%, and the specificity was 40%, 70% and 70%, respectively. The low specificities for these agents were mainly due to high positive uptake in patients with active pulmonary tuberculosis. There were no significant differences in uptake ratios and retention index between malignant and benign lesions, and among the histologic types of lung cancer. Conclusion : $^{201}TI$ and $^{99m}Tc$ - MIBI showed higher sensitivity than $^{99m}Tc$(V) - DMSA for detecting lung cancer, but was of limited usefulness in distinguishing lung cancer from benign lesion due to low specificity, especially in area with a high prevalence of active pulmonary tuberculosis.

• Tuberculosis and Respiratory Diseases
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• v.55 no.5
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• pp.506-515
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• 2003

Background : A decreased level of serum arginine vasopressin(AVP) and an increased sensitivity to an exogenous AVP is expected in patients with septic shock who often require a high infusion rate of catecholamines. The goal of the study was to determine whether an exogenous AVP infusion to the patients with septic shock would achieve a significant decrement in infusion rate of catecholamine vasopressors while maintaining hemodynamic stability and adequate urine output. Method : Eight patients with septic shock who require a high infusion rate of norepinephrine had received a trial of 4-hour AVP infusion with simultaneous titration of norepinephrine. Hemodynamic parameters and urine output were monitored during the AVP infusion and the monitoring continued up to 4 hours after the AVP infusion had stopped. Results : Mean arterial pressure showed no significant changes during the study period(p=0.197). Norepinephrine infusion rate significantly decreased with concurrent AVP administration(p=0.001). However, beneficial effects had disappeared after the AVP infusion was stopped. In addition, hourly urine output showed no significant changes throughout the trials(p=0.093). Conclusion : Concurrent AVP infusion achieved the catecholamine vasopressor sparing effect in the septic shock patients, but there was no evidence of the improvement of renal function. Further study may be indicated to determine whether AVP infusion would provide an organ-protective effect to the septic shock patients.

• Tuberculosis and Respiratory Diseases
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• v.59 no.5
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• pp.473-479
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• 2005

Background : A pulmonary embolism often presents with nonspecific symptoms and signs. However, a delayed diagnosis can result in catastrophic outcome. The majority of preventable deaths associated with a pulmonary embolism can be ascribed to a missed diagnosis rather than to the failure of existing treatments. Therefore, accurate and rapid diagnostic methods are essential for the management of a pulmonary embolism. The recent generation of multidetector-row spiral CT scanners appears to outperform other imaging modalities in detecting a central and peripheral pulmonary embolism. However, there are some variations in the interpretations of the findings between observers. This study examined the inter-observer differences of the diagnoses in patients with a pulmonary embolism. Method : 64 patients who were diagnosed with a pulmonary embolism either clinically or with spiral chest CT from 2002 to 2004, were included. Two thoracic radiologists interpreted the multidetector-row spiral CT in terms of the diagnosis of a pulmonary embolism and the location of the thrombus independently. Among 64 patients, 14 patients were excluded because there was no evidence of a pulmonary embolism or there was different interpretation of the pulmonary embolism between radiologists. A clinical diagnosis was based on "Rules for predicting the probability of embolism". Results : The mean score of the patients according to the Wells method was $3.91{\pm}0.30$ (0-9). The accordance of the radiologists was 95% in the main, 85% in the lobar, 91.2% in the segmental, and 96% in the sub-segmental pulmonary arteries. After excluding the negative interpretation from both radiologists, their agreement was 76.2%(${\kappa}.$ 0.83) in the main, 57.6%(${\kappa}.$ 0.63) in the lobar, 51.5%(${\kappa}.$ 0.63) in the segmental, and 34.6%(${\kappa}.$ 0.49) in the sub-segmental pulmonary arteries. Conclusion : Chest CT has been recently applied to patients suspected of having a pulmonary embolism. It was found that spiral CT is a rapid test for diagnosing a thrombus, and there was reliable accordance between the observers from the area of the large pulmonary arteries. However, there was a lack of agreement between the observers in diagnosing thrombi located distal to the sub-segmental arteries.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.397-405
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• 2005

Background : Laminin-1 is known to have regular functions in the development and course of differentiation of the lungs. The morphogenesis and distribution of laminin-1 still remains as a mystery and its distribution and changes in the molecular structure of laminin-1 in the pathogenesis of the lung still is a subject of great controversy. In this study, experiments were done to delineate the distribution and changes in the amount of laminin-1 after inducing inflammation of the lungs by exposing experimental animals to CS gas and especially, to find compositions of laminin-1 within type II pneumocytes. Materials and Methods : The experimental subjects of study were newborn rats and the extracted tissue from the experimental rats were viewed under light microscope and electron microscope after the sections were treated with immunohistochemical methods and immunogold reaction methods using bounded gold particles. Results : 1) Lymphocytes and mononuclear phagocytes invaded the alveolar septa in the 2 day group rats after CS gas exposure and intense interstitial inflammation was seen in the 3 day group. 2) Laminin immunoreactions decreased to a moderate degree in the 2 and 3 day group rats after CS gas exposure and strong laminin immunoreactions were seen again in the 5 and 7 day group rats. 3) Gold particles in basal lamina of the lung blood-air barrier decreased and in the type I pneumocytes decreased in the 2 and 3 day group rats after CS gas exposure. 4) Gold particles were seen only on the surface of the cell membranes of type II pneumocytes of the 1 and 2 day group rats after CS gas exposure. 5) Few gold particles around the lamellar bodies and cytoplasm of type II pneumocytes in the control rat group and at 12 hours after CS gas exposure. Gold particles are seen only on the surface of type II pneumocytes of the 1 and 2 day group rats after CS gas exposure and are evenly distributed in small amounts in the cells of the 3 day group after CS gas exposure. Conclusion : CS gas exposure in the rats caused inflammation of lung alveolar septa and also induced a decrease in laminin-1 in basal lamina and loss of laminin-1 in the cytoplasm of type II pneumonocytes. As the inflammatory cells disappeared, an increase in the distribution of laminin-1 occurred. This reflects tissue regeneration functions of laminin-1 in the pneumocytes of rats and the distribution of laminin-1 in type II pneumocytes can be seen through the electron microscope using immunogold methods.

• Tuberculosis and Respiratory Diseases
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• v.54 no.1
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• pp.91-103
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• 2003

Background : Histamine is widely distributed in the lung. It increases capillary permeability and the P-selectin expression on vascular endothelial cell surfaces. We studied the role of endogenous histamine on the pathogenesis of endotoxin-induced acute lung injury (ALI) in rats. Methods: We instilled either normal saline (control group) or lipopolysaccharide (3 mg/Kg, LPS group) to tracheas of Sprague-Dawley rats. H1-receptor blocker (mepyramine, 10 mg/Kg, H1RB group), H2-receptor blocker (ranitidine, 10 mg/Kg, H2RB group), and H3-receptor blocker (thioperamide, 2 mg/Kg, H3RB group) were administered through vein or peritoneum along with intratracheal LPS administration. Statistical significance was accepted at p<0.05. Results : LPS increases the histamine level in BAL fluid significantly at 2 h after the treatment compared with control group. LPS significantly increases protein concentration, PMN cell count in bronchoalveolar lavage (BAL) fluid, and myeloperoxidase (MPO) activity in the lung tissue at 6 h compared to control group. PMN cell count in BAL fluid and MPO activity in lung tissue were significantly lower in H2RB-group compared to LPS-group. However, protein concentration in BAL fluid showed no significant differences between the LPS alone and LPS with histamine receptor blockade. Conclusions : Endogenous histamine might be involved in the recruitment of PMNs in LPS-induced ALI via H2 receptor. However, its role in ALI would not be significant in this model.