• The korean journal of orthodontics
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• v.20 no.1
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• pp.47-59
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• 1990

Respiration is one of the most important functions which are carried out in stomatognathic system. When nasal orifice is obstructed or the resistance of upper airway is increased mouth breathing is initiated. Mouth breathing is regarded as an important etiologic factor of dentofacial anomalies. This experiment was performed to observe the influences of metabolic acidosis, tracheal resistance and vagotomy on mouth breathing. After rabbits were anesthetized with sodium pentobarbital, a pair of wire electrode was inserted into mylohyoid muscle, anterior belly of digastric muscle and dilator naris muscle to record EMG activity. Femoral vein and artery were cannulated for infusion of 0.3N HCl and collection of blood sample to determine the blood pH, and tracheal intubation was done to control airway resistance. Mouth breathing was induced by metabolic acidosis. Increase of the airway resistance through tracheal cannula intensified the activity of dilator naris, mylohyoid and digastric muscle. The higher the resistance, the larger the EMG amplitude. After bilateral vagotomy, respiratory volume and inspiatory time were increased and the activities of dilator naris, mylohyoid and digastric muscle were strengthened. It was concluded that the muscle activity related to mouth breathing was induced by metabolic acidosis and increase of tracheal tube resistance.

• Tuberculosis and Respiratory Diseases
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• v.66 no.3
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• pp.198-204
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• 2009

Background: First-line drugs, if sensitive, are the most potent drugs in the treatment of multidrug-resistant tuberculosis (MDR-TB). This study examined the frequency and risk factors associated with acquired drug resistance to first-line drugs during a standardized treatment using first-line drugs in patients with MDR-TB. Methods: This study included patients who were diagnosed with MDR-TB at the National Masan Tuberculosis Hospital between January 2004 and May 2008, treated with standardized first-line drugs, and for whom the preand post-treatment results of the drug susceptibility test were available. Their medical records were reviewed retrospectively. Results: Of 41 MDR-TB patients, 14 (34.1%) acquired additional resistance to ethambutol (EMB) or pyrazinamide (PZA). Of 11 patients initially resistant to isoniazid (INH) and rifampicin (RFP), 3 (27.3%) acquired additional resistance to both EMB and PZA, and 3 (27.3%) to PZA. Of 18 patients initially resistant to INH, RFP and EMB, 6 (33.3%) acquired additional resistance to PZA. Of 6 patients initially resistant to INH, RFP and PZA, 2 (33.3%) acquired additional resistance to EMB. Ten of the 41 MDR-TB patients (24.4%) changed from resistant to susceptible. No statistically significant risk factors associated with acquired resistance could be found. Conclusion: First-line drugs should be used cautiously in the treatment of MDR-TB in Korea considering the potential acquisition of drug resistance.

• Clinical and Experimental Pediatrics
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• v.48 no.1
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• pp.40-47
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• 2005

Purpose : S. pneumoniae is one of major pathogens of community-acquired respiratory infections. The rate of antibiotic resistance to this organism has increased, and resistance to multiple antimicrobial agents in a single strain of S. pneumoniae may compromise the efficacy of empiric antimicrobial treatment commonly used for respiratory infections. We did this study to find out the penicillin resistant distributions and oral antibiotics susceptibility patterns against S. pneumoniae, isolated from pediatric patients with community-acquired respiratory infections in Korea. Methods : One hundred fifty six pneumococcal isolates obtained from pediatric patients with community-acquired respiratory infections such as acute otitis media(AOM), sinusitis and pneumonia between May 2000 to June 2003. And MICs of penicillin and oral antibiotics(amoxicillin, amoxicillin-clavulanate, cefaclor) were performed by broth microdilution methods according to the NCCLS(2003a). Results : Seventy eight percent of the isolates were resistant to penicillin. The isolates, collected from AOM patients showed the highest penicillin resistance(92.7%). The resistant rates of amoxicillin (16.7%) and amoxicillin-clavulanate(9.6%), based on susceptibility breakpoints established by the NCCLS, were markedly lower than these of penicillin. But, the resistant rate of cefaclor was very high, above 95%. Conclusion : We concluded that pneumococci isolated from study cases may be one of the world's highest penicillin resistant rates. But, amoxicillin and amoxicillin-clavulanate can be used as a first-line antibiotics. Finally, we hope that a continuous surveillance study to monitor resistant patterns of pneumococcal respiratory infections will be needed for the standard guidelines of empiric antibiotic treatment.

• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1022-1030
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• 1998

Background : In volume-controlled ventilation, the use of inspiratory pause increases the inspiratory time and thus increases mean airway pressure and improves ventilation. But under the same I : E ratio, the effects of inspiratory pause on mean airway pressure and gas exchange are not certain. Moreover, the effects may be different according to the resistance of respiratory system. So we studied the effects of inspiratory pause on airway pressure and gas exchange under the same I : E ratio in volume-controlled ventilation. Methods: Airway pressure and arterial blood gases were evaluated in 12 patients under volume-controlled mechanical ventilation with and without inspiratory pause time 5%. The I : E ratio of 1 : 3, $FiO_2$, tidal volume, respiratory rate, and PEEP were kept constant. Results: $PaCO_2$ with inspiratory pause was lower than without inspiratory pause ($38.6{\pm}7.4$ mmHg vs. $41.0{\pm}7.7$ mmHg. p<0.01). P(A-a)$O_2$ was not different between ventilation with and without inspiratory pause $185.3{\pm}86.5$ mmHg vs. $184.9{\pm}84.9$ mmHg, p=0.766). Mean airway pressure with inspiratory pause was higher than without inspiratory pause ($9.7{\pm}4.0\;cmH_2O$ vs. $8.8{\pm}4.0\;cmH_2O$, p<0.01). The resistance of respiratory system inversely correlated with the pressure difference between plateau pressure with pause and peak inspiratory pressure without pause (r=-0.777, p<0.l), but positively correlated with the pressure difference between peak inspiratory pressure with pause and peak inspiratory pressure without pause (r=0.811, p<0.01). Thus the amount of increase in mean airway pressure with pause positively correlated with the resistance of respiratory system (r=0.681, p<0.05). However, the change of mean airway pressure did not correlated with the change of $PaCO_2$. Conclusion: In volume-controlled ventilation under the same I : E ratio of 1 : 3, inspiratory pause time of 5% increases mean airway pressure and improves ventilation. Although the higher resistance of respiratory system, the more increased mean airway pressure, the increase in mean airway pressure did not correlated with the change in $PaCO_2$.

• Tuberculosis and Respiratory Diseases
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• v.63 no.1
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• pp.42-51
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• 2007

Background: TRAIL is a cytokine that selectively induces apoptosis in various cancer cell lines. Gefitinib is new targeted drug applied in lung cancer that selectively inhibits EGFR tyrosine kinase. However, lung cancers have shown an initial or acquired resistance to these drugs. This study examined the effect of IGF-1R and its blockade on enhancing the sensitivity of lung cancer cell lines to TRAIL and gefitinib. Methods: Two lung cancer cell lines were used in this study. NCI H460 is very sensitive to TRAIL and gefitinib. On the other hand, A549 shows moderate resistance to TRAIL and gefitinib. The IGF-1R blockade was performed using adenoviruses expressing the dominant negative IGF-1R and shRNA to IGF-1R and AG1024 (IGF-1R tyrosine kinase inhibitor). Results: The adenovirus expressing dominant negative IGF-1R(950st) induced the increased expression of defective IGF-1R on the lung cancer cell surface, and the adenovirus-shIGF-1R effectively decreased the level of IGF-1R expression on cell surface. The genetic blockade of IGF-1R by the adenovirus-dnIGF-1R and AG1024 increased the sensitivity of A549 cells to TRAIL. The reduction of IGF-1R by transduction with ad-shIGF-1R also increased the sensitivity of the A549 cells to gefitinib. Conclusion: The blockade of IGF-1R through various mechanisms increased the sensitivity of the lung cancer cell line that was resistant to TRAIL and gefitinib. However, further studies using other cell lines showing acquired resistance as well as in vivo animal experiments will be needed.

• Tuberculosis and Respiratory Diseases
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• v.80 no.3
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• pp.270-276
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• 2017

Background: A disputed rpoB mutation is a specific type of rpoB mutation that can cause low-level resistances to rifampin (RIF). Here, we aimed to assess the frequency and types of disputed rpoB mutations in Mycobacterium tuberculosis isolates from South Korea. Methods: Between August 2009 and December 2015, 130 patients exhibited RIF resistance on the MTBDRplus assay at Asan Medical Center. Among these cases, we identified the strains with disputed rpoB mutation by rpoB sequencing analysis, as well as among the M. tuberculosis strains from the International Tuberculosis Research Center (ITRC). Results: Among our cases, disputed rpoB mutations led to RIF resistance in at least 6.9% (9/130) of the strains that also exhibited RIF resistance on the MTBDRplus assay. Moreover, at the ITRC, sequencing of the rpoB gene of 170 strains with the rpoB mutation indicated that 23 strains (13.5%) had the disputed mutations. By combining the findings from the 32 strains from our center and the ITRC, we identified the type of disputed rpoB mutation as follows: CTG511CCG (L511P, n=8), GAC516TAC (D516Y, n=8), CTG533CCG (L533P, n=8), CAC526CTC (H526L, n=4), CAC526AAC (H526N, n=3), and ATG515GTG (M515V, n=1). Conclusion: Disputed rpoB mutations do not seem to be rare among the strains exhibiting RIF resistance in South Korea.

• Tuberculosis and Respiratory Diseases
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• v.72 no.1
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• pp.44-49
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• 2012

Background: Multidrug-resistant tuberculosis (MDR-TB) is an increasing public health problem and poses a serious threat to global TB control. Fluoroquinolone (FQ) and aminoglycoside (AG) are essential anti-TB drugs for MDR-TB treatment. REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ (M&D, Wonju, Korea) were evaluated for rapid detection of FQ and kanamycin (KM) resistance in MDR-TB clinical isolates. Methods: M. tuberculosis (n=67) were isolated and cultured from the sputum samples of MDR-TB patients for extracting DNA of the bacilli. Mutations in genes, gyrA and rrs, that have been known to be associated with resistance to FQ and KM were analyzed using both REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$, respectively. The isolates were also utilized for a conventional phenotypic drug susceptibility test (DST) as the gold standard of FQ and KM resistance. The molecular and phenotypic DST results were compared. Results: Sensitivity and specificity of REBA MTB-FQ$^{(R)}$ were 77 and 100%, respectively. Positive predictive value and negative predictive value of the assay were 100 and 95%, respectively, for FQ resistance. Sensitivity, specificity, positive predictive value and negative predictive value of REBA MTB-KM$^{(R)}$ for detecting KM resistance were 66%, 94%, 70%, and 95%, respectively. Conclusion: REBA MTB-FQ$^{(R)}$ and REBA MTB-KM$^{(R)}$ evaluated in this study showed excellent specificities as 100 and 94%, respectively. However, sensitivities of the assays were low. It is essential to increase sensitivity of the rapid drug resistance assays for appropriate MDR-TB treatment, suggesting further investigation to detect new or other mutation sites of the associated genes in M. tuberculosis is required.

• Tuberculosis and Respiratory Diseases
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• v.38 no.2
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• pp.99-107
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• 1991

Drug resistance of M. tuberculosis has been investigated with isolates from patients screened out of the sample population of the nationwide tuberculosis prevalence surveys or from the routine cultures. The results showed a close inverse relationship between prevalence of drug resistance and efficiency of the past or current treatment regimens of NTP. Individual drug resistance also showed a close relationship with the extent of use of the relevant drugs. Drug resistance was found in 38.0% of M. tuberculosis isolates from patients found in 1965 survey and remained unchanged until it increased upto 48.0% in 1980 survey. The resistance prevalence, however, dropped to 30.8% in 1985 and further to 25.3% in 1990 survey. Such decrease was fairly well coincided with a continuous increase of the treatment efficiency (from 60% in 1984 to 77% in 1989) in 1980s. Initial drug resistance also showed a similar trend, namely 26.2% in 1965, 23.9% in 1970, 20.1% in 1975, 30.6% in 1980, 17.4% in 1985, and 15.0% in 1990. The similar figures were observed in M. tuberculosis isolates from patients diagnosed in the routine services. Higher prevalence of initial drug resistance was observed among urban patients than rural patients and among young patients than old patients. These findings signify that a continuous survey on drug resistance permits to monitor efficiency of treatment programme of the country.

• Clinical and Experimental Pediatrics
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• v.54 no.2
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• pp.64-68
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• 2011

Purpose: The normal values for lung resistance and lung capacity of children, as determined by impulse oscillometry (IOS), are different for children of different ethnicities. However, reference values there is no available reference value for Korean preschool children have yet to be determined. The aim of the present study was to determine the normal ranges of IOS parameters in Korean preschool children. Methods: A total of 133 healthy Korean preschool children were selected from 639 children (aged 3 to 6 years) who attended kindergarten in Seongnam, Gyeonggi province, Korea. Healthy children were defined according to the European Respiratory Society (ERS) criteria. All subjects underwent lung function tests using IOS. The relationships between IOS value (respiratory resistance (Rrs) and reactance (Xrs) at 5 and 10 Hz and resonance frequency (RF)) and age, height, and weight were analyzed by simple linear and multiple linear regression analyses. Results: The IOS success rate was 89.5%, yielding data on 119 children. Linear regression identified height as the best predictor of Rrs and Xrs. Using stepwise multiple linear regressions based on age, height, and weight, we determined regression equations and coefficients of determination ($R^2$) for boys ($Rrs_5=1.934-0.009{\times}Height$, $R^2$=12.1%; $Xrs_5=0.774+0.006{\times}Height-0.002{\times}Age$, $R^2$=20.2% and for girls $(Rrs_5=2.201-0.012{\times}Height$, $R^2$=18.2%; $Xrs_5=-0.674+0.004{\times}Height$, $R^2$=10.5%). Conclusion: This study provides reference values for IOS measurements of normal Korean preschool children. These provide a basis for the diagnosis and monitoring of preschool children with a variety of respiratory diseases.

• PNF and Movement
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• v.5 no.2
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• pp.63-71
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• 2007

Objective : Respiratory muscle weakness and decreased chest mobility has been suggested to result from the deconditioning that accompanied activity level in chronic elderly stokes. The benefits of respiratory exercise programmes on exercise capacity and muscle strength in hemiplegia. This study aimed to determine the effects of selective inspiratory and expiratory muscles training and chest mobility exercise on patients with strokes to establish if an improved exercise capacity can be obtained in patients that are not limited in their daily activities. Methods & Intervention : Twelve patients were assigned to the intensive respiratory exercise group participated in a measures design that evaluated the subjects with pre-treatment and post-treatment. Thirteen subjects who were assigned to a control group received training with breathing exercise and resistance exercise of skeletal muscles. The subjects performed spirometry then undertook a 6-week programme of respiratory muscle and chest mobility training. Training for the two groups was carried out 2 times a week for 6 weeks. Measurements and Results : Spirometry(Forced Vital Capacity: FVC and Closed Circuit Spiromety: CCS) and thoracic mobility were measured before and after the 6 weeks. The experimental group improved significantly compared to control group in FVC, $FEV_1$, MVV, IRV and ERV, and upper chest wall expansion(p<0.05). No significant improvement was seen in thoracic mobility or lung function in control group(p>0.05). Conclusion : The major findings in this study were that a intensive 6week exercise programme of resistive breathing and chest mobility in patients with hemiplegia led to an increase in lung capacity. The resistive breathing exercise programme used here resulted in a significant increase in the chest excursion during breathing.