• Clinical and Experimental Pediatrics
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• v.52 no.5
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• pp.529-537
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• 2009

Drug-resistant tuberculosis in children has important implications for both the patients and tuberculosis control programs. In Korea, among all new patients, the isoniazid resistance rate was 9.9% and multidrug-resistant tuberculosis rate was 2.7% in 2004 (in patients aged 10-19 yr, the multidrug-resistant tuberculosis rate reached 2.1%). Tuberculosis in pediatric patients is difficult to diagnose because many children have nonspecific clinical signs and the detection rates of acid-fast bacilli smears and cultures are low. Therefore, every effort should be made to identify adult sources and obtain information on drug susceptibility because symptomatic adult patients have a higher chance of culture positivity and drug-susceptibility patterns are the same in most adult-child pair patients. Korean children are at significant risk of drug-resistant tuberculosis. As the isoniazid resistance rate is greater than 4% among the new cases in Korea, a four-drug regimen should be considered for initial treatment of children with active tuberculosis, unless drug-susceptibility test results are available. Treatment of drug-resistant tuberculosis in children is challenging and there are only few available data. Tuberculosis control programs should be continuous with specific focus on pediatric populations because they can serve as reservoirs for future active cases. Further studies are needed regarding treatment of drug-resistant tuberculosis in children.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.41-46
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• 1986

When barium titanate was synthesized in solid-solid reaction the abnormal expansion occurred from 90$0^{\circ}C$ to 110$0^{\circ}C$. The equi molecular mixture of $BaCo_3$ and $TiO_2$ was sintered from 90$0^{\circ}C$ to 130$0^{\circ}C$ on the condition of air vacuum and $CO_2$ atomosphere. After that the specimens were tested closely with XDR Dilatometer and SEM The result indicated that: 1, Volume expansion to be synthesized barium titanate in solid-solid reaction was affected by atomosphere sintering. 2. The solid reaction ot fiorm barium titanate in vacuum atomosphere occurred faster than that in air atomosphere. In vacuum atomosphere the maxium volume expansion was about 30% at 90$0^{\circ}C$ for 2hrs, 3. The solid reaction to form barium titanate in 4CO_2$ atomosphere occurred slower than that in air atomosphere. In $CO_2$ atomosphere the maximum volume expansion was 13% at 100$0^{\circ}C$ for 2 hrs. 4. According to the result of x-ray the expanison was caused by the reaction to form $BaTiO_3$ and change $Ba_2TiO_4$ into 4BaTiO_3$.

• Tuberculosis and Respiratory Diseases
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• v.85 no.2
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• pp.111-121
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• 2022

Multidrug-resistant tuberculosis (MDR-TB) is caused by an organism that is resistant to both rifampicin and isoniazid. Extensively drug-resistant TB, a rare type of MDR-TB, is caused by an organism that is resistant to quinolone and one of group A TB drugs (i.e., linezolid and bedaquiline). In 2018, the World Health Organization revised the groupings of TB medicines and reclassified linezolid as a group A drug for the treatment of MDR-TB. Linezolid is a synthetic antimicrobial agent in the oxazolidinone class. Although linezolid has a good efficacy, it can cause substantial adverse events, especially hematologic toxicity. In both TB infection and linezolid mechanism of action, mitochondrial dysfunction plays an important role. In this concise review, characteristics of linezolid as an anti-TB drug are summarized, including its efficacy, pathogenesis of hematologic toxicity highlighting mitochondrial dysfunction, and the monitoring and management of hematologic toxicity.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.423-432
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• 2022

Magnetic biochar produced from pyrolysis of dairy cattle manure was used to develop an effective sorbent for arsenic purification from aqueous solution. Biomass and magnetized biomass were pyrolyzed in a tube furnace with 10 ℃/min heating rate at 450 ℃ under nitrogen flow of 100 cm³/min for 2 h. Biochars were characterized by SEM-EDX, BET, XDR, FTIR, TGA, zeta potential analysis. The resultant biochar and magnetic biochar were opposed to 50-100-500 ppm As(V) laden aqueous solution. Adsorption experiments were performed by using ASTM 4646-03 batch method. The effects of concentration, pH, temperature and stirring rate on adsorption were evaluated. As(V) was successfully removed from aqueous solution by magnetic biochar due to its highly porous structure, high aromaticity and polarity. The results suggest dairy cattle manure pyrolysis is a promising route for managing animal manure and producing a cost effective biosorbent for efficient immobilization of arsenic in aqueous solutions.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.157-163
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• 2016

Purpose: It is to compare and evaluate the change of the wear rate and phase variation of the Zirconia before and after the sintering after the grinding by a high speed equipment manufactured for the Zirconia. Methods: The specimen of the sintered Zirconia was manufactured as size of $15mm{\times}15mm{\times}2mm$. The grinding has been applied to each of all pieces of each test groups for a minute fit for each condition at same speed of 50,000 rpm by a diamond bur at high speed handpiece with injection of the air and water. For the observation of the surface before and after the sintering of the each test piece, the cross section of it was observed as 100 magnification by a scanning electron microscope after it was coated by PT, and the diffraction analysis was performed by XDR to compare the crystal phase of the Zirconia. The average surface roughness value of all specimens were evaluated. The wear test was performed at room temperature by applying a load of 1kg for 120,000 cycles for the chewing period 6 months. Wear was analyzed for the enamel cusps by measurement of the vertical substance loss with a laser scanner. Conclusion: The phase variation from the tetragonal phase to the monoclinic phase was confirmed in the test group of the pre-sintered Zirconia after the grinding, and the value of the surface roughness and the wear rate was increased in experimental group.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.61-67
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• 2009

Purpose : The rate of drug-resistant tuberculosis (DR-TB) in children is an indicator of the effectiveness of TB control programs in the community. This study aimed to assess the prevalence of DR-TB in children and evaluate TB management. Methods : Between January 1999 and July 2007, drug susceptibility tests for anti-TB drugs were employed for patients aged less than 19 years with culture-positive TB. Results : A total of 607 cases (16.6%) were resistant to at least one anti-TB drug as follows: isoniazid (INH; 13.8%), rifampin (8.9%), pyrazinamide (4.2%), streptomycin (3.7%), ethambutol (EMB; 5.9%), and para-aminosalicylic acid (PAS; 1.9%). Multidrug-resistant (MDR) TB was found in 276 cases (7.6%); extensive drug resistant (XDR) TB, in 5 cases (0.2%). The rate of resistance to at least one anti-TB drug in children aged >15 years (16.1%) was significantly lower than that in children aged <15 years (20.5%) (P=0.016). The rate of resistance to at least one anti-TB drug and multidrug-resistance in this survey decreased significantly (P<0.001) as compared to the previous survey (1987-1995). The rate of resistance to INH, EMB, and PAS also significantly decreased (P<0.05). Conclusion : The rate of DR-TB in children in Korea has decreased over time; however, it remains higher than that in other countries. MDR-TB and XDR-TB are the emerging problems in Korean children. Therefore, the selection of effective drugs through drug susceptibility tests and evaluating risk factors of resistant TB is essential to successful therapy and a decreased incidence of DR-TB.

• Tuberculosis and Respiratory Diseases
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• v.64 no.2
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• pp.87-94
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• 2008

Background: Surveillance of TB drug resistance (DR) is essential for providing information on the magnitude and trends in resistance, for developing treatment guidelines and for monitoring the effect of interventions. Up to now national surveys of drug resistance of M. tuberculosis have been conducted four times since 1994 among patients registered at health centers. The purpose of this study is to estimate the prevalence of primary drug resistance among new cases identified in private sector, and to compare it with the previous national drug resistance surveys. Methods: The study collected results of drug susceptibility testing (DST) performed at the Korean Institute of Tuberculosis by the request of private sector from January 2003 to December 2005, and then finally selected new cases for the analysis from the database of Korean TB Surveillance (KTBS) by matching patients' name and social identification numbers. Results: Of the 5,132 new patients included in the study, 689 (13.4%) patients were found to have drug resistance at least one drug, 530 patients (10.3%) were isoniazid resistant, 195 patients (3.8%) were multi-drug resistant (MDR), and 21 patients (0.4%) were extensively drug resistant (XDR). The rate of drug resistance tended to decrease annually but it was not statistically significant. When compared with previous national DR surveys in 2003 and in 2004 respectively, they were not significantly different. Conclusion: The prevalence of DR among new cases managed in the private sector did not show significant difference from that of new patients registered in the public sector in the same year.