• Tuberculosis and Respiratory Diseases
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• v.50 no.5
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• pp.599-606
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• 2001

Background : Since the advent of AIDS, tuberculosis has become a major public health problem in the western society. Therefore, it is essential that pulmonary tuberculosis be rapidly diagnosed. Light microscopic detection of acid-fast organisms in sputum has traditionally been used for rapidly diagnosing tuberculosis. However positive smears are only observed in about one-half to three-quarters of cases. Studies using PCR for diagnosing pulmonary tuberculosis disclosed several shortcomings suggesting an inability to distinguish between active and treated or inactive tuberculosis. In this study, the clinical significance of a PCR-based rapid technique for detecting Mycobacterium tuberculosis DNA in peripheral blood was investigated. Materials and Methods : From July 1, 1998 through to August 30, 1999, 59 patients with presumed tuberculosis, who had no previous history of anti-tuberculosis medication use within one year prior to this study were recruited and followed up for more than 3 months. AFB stain and culture in the sputum and/or pleural fluids and biopsies when needed were performed. Blood samples from each of the 59 patients were obtained in order to identify Mycobacterium Tuberculosis DNA by a PCR test. Results : 1) Forty five out of 59 patients had a final diagnosis of tuberculosis ; Twenty eight were confirmed as having active pulmonary tuberculosis by culture or biopsy. Four were clinically diagnosed with pulmonary tuberculosis. The other 13 patients were diagnosed as having tuberculous pleurisy (9) and extrapulmonary tuberculosis (4). 2) Fourteen patients showed a positive blood PCR test. The PCR assay correctly identified active tuberculosis in 13 out of 14 patients. The overall sensitivity and specificity of this blood peR assay for diagnosing tuberculosis were 29% and 93%, respectively. The positive predictive value was 93%, the negative predictive value was 29% and the diagnostic accuracy was 44%.3) Six out of 14(43%) patients with blood PCR positive tuberculosis were immunologically compromised hosts. 4) A simple chest radiograph in blood PCR positive tuberculosis patients showed variable and inconsistent findings. Conclusion : A peripheral blood PCR assay for Mycobacterium tuberculosis is not recommended as a screening method for diagnosing active tuberculosis. However, it was suggested that the blood PCR assay could contribute to an early diagnostic rate due to its high positive predictive value.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.556-566
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• 2010

A new kinetic spectrophotometric method is developed for the measurement of Mn(II) in natural water samples. The method is based on the catalytic effect of Mn(II) with the oxidation of Gallocyanin by $KIO_4$ using nitrilotriacetic acid (NTA) as an activation reagent at 620 nm. The optimum conditions obtained are $4.00{\times}1^{-5}\;M$ Gallocyanin, $KIO_4$, $1.00{\times}10^{-4}\;M$ NTA, 0.1 M HAc/NaAc buffer of pH = 3.50, the reaction time of 5 min and the temperature of $30^{\circ}C$. Under the optimum conditions, the proposed method allows the measurement of Mn(II) in a range of $0.1\;-\;4.0\;ng\;mL^{-1}$ and with a detection limit of down to $0.025\;ng\;mL^{-1}$. The recovery efficiency in measuring the standard Mn(II) solution is in a range of 98.5 - 102%, and the RSD is in a range of 0.76 - 1.25%. The newly developed kinetic method has been successfully applied to the measurement of Mn(II) in both some environmental water samples and certified standard reference river water sample, JAC-0031 with satisfying results. Moreover, few cations and anions interfere with the measurement of Mn(II). Compared with the other catalytic-kinetic methods and instrumental methods, the proposed kinetic method shows fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can easily and successfully be applied to the real water samples with relatively low salt content and complex matrices such as bottled drinking water, cold and hot spring waters, lake water, river water samples.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.141-152
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• 2020

The rapid on-site measurement of hydroponic nutrients allows for the more efficient use of crop fertilizers. This paper reports on the development of an embedded on-site system consisting of multiple ion-selective electrodes (ISEs) for the real-time measurement of the concentrations of macronutrients in hydroponic solutions. The system included a combination of PVC ISEs for the detection of NO₃, K, and Ca ions, a cobalt-electrode for the detection of H₂PO₄, a double-junction reference electrode, a solution container, and a sampling system consisting of pumps and valves. An Arduino Due board was used to collect data and to control the volume of the sample. Prior to the measurement of each sample, a two-point normalization method was employed to adjust the sensitivity followed by an offset to minimize potential drift that might occur during continuous measurement. The predictive capabilities of the NO₃ and K ISEs based on PVC membranes were satisfactory, producing results that were in close agreement with the results of standard analyzers (R² = 0.99). Though the Ca ISE fabricated with Ca ionophore II underestimated the Ca concentration by an average of 55%, the strong linear relationship (R² > 0.84) makes it possible for the embedded system to be used in hydroponic NO₃, K, and Ca sensing. The cobalt-rod-based phosphate electrodes exhibited a relatively high error of 24.7±9.26% in the phosphate concentration range of 45 to 155 mg/L compared to standard methods due to inconsistent signal readings between replicates, illustrating the need for further research on the signal conditioning of cobalt electrodes to improve their predictive ability in hydroponic P sensing.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• Pediatric Infection and Vaccine
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• v.26 no.2
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• pp.81-88
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• 2019

Purpose: Early detection of Mycoplasma pneumoniae is important for appropriate antimicrobial therapy in children with pneumonia. This study aimed to evaluate the diagnostic value of a rapid antigen test kit in detecting M. pneumoniae from respiratory specimens in children with lower respiratory tract infection (LRTI). Methods: A total of 215 nasopharyngeal aspirates (NPAs) were selected from a pool of NPAs that had been obtained from children admitted for LRTI from August 2010 to August 2018. The specimens had been tested for M. pneumoniae by culture and stored at $-70^{\circ}C$ until use. Tests with Ribotest $Mycoplasma^{(R)}$ were performed and interpreted independently by two investigators who were blinded to the culture results. Results: Among the 215 NPAs, 119 were culture positive for M. pneumoniae and 96 were culture negative. Of the culture-positive specimens, 74 (62.2%) were positive for M. pneumoniae by Ribotest $Mycoplasma^{(R)}$, and 92 of the 96 (95.8%) culture-negative specimens were negative for M. pneumoniae by Ribotest $Mycoplasma^{(R)}$. When culture was used as the standard test, the sensitivity and specificity of Ribotest $Mycoplasma^{(R)}$ were 62.2% and 95.8%, respectively. Additionally, the positive predictive value, negative predictive value, and overall agreement rates with Ribotest $Mycoplasma^{(R)}$ were 94.9%, 67.2%, and 77.2%, respectively. Conclusions: A positive test result of Ribotest $Mycoplasma^{(R)}$ suggests a high likelihood of culture-positive M. pneumoniae infection. However, a negative test result should be interpreted with caution because nearly one-third of negative test results reveal culture-positive M. pneumoniae infections.

• Laboratory Medicine Online
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• v.1 no.2
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• pp.100-104
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• 2011

Background: Malaria is a problematic disease in Korea, and microscopic examination of Giemsa-stained blood smear has been used as the gold standard for its diagnosis. However, this technique is time-consuming and has low sensitivity in samples with low numbers of malarial parasites (<20 parasites/μL). Here, we evaluated the performance characteristics of the LG Advansure^TM Malaria P.f./P.v. real-time QPCR (LG life sciences, Korea). Methods: Blood samples from 173 persons who visited Korea University Ansan Hospital were evaluated. QPCR was performed in 73 malaria patients and 100 healthy subjects by using the LG Advansure Malaria P.f./P.v. real-time QPCR^R kit, and the results were compared with those of microscopy. The detection limit of this kit was determined by serial dilution of Plasmodium-infected blood with normal blood (blood not infected with Plasmodium). Results: Among the 73 patients that were microscopically confirmed to have malaria (Plasmodium vivax infection, N=70, P. falciparum infection, N=3), 69 patients were diagnosed with P. vivax infection and 3 were diagnosed with P. falciparum infection by LG Advansure^TM Malaria P.f./P.v. realtime QPCR. Both the tests indicated absence of infection in the 100 healthy subjects. The detection limit of LG Advansure^TM Malaria P.f./P.v. real-time QPCR was 0.1 parasite/μL. Conclusions: LG Advansure^TM Malaria P.f./P.v. real-time QPCRis a very sensitive and specific technique and can be used as a confirmatory test for malaria.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.558-570
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• 1996

Background : The detection of Collapsible airways has important therapeutic implications in chronic airway disease and bronchial asthma. The distinction of a purely collapsible airways disease from that of asthma is important because the treatment of the dormer may include the use of pursed lip breathing or nasal positive pressure ventilation whereas in the latter, pharmacologic approaches are used. One form of irreversible airflow limitation is collapsible airways, which has been shown to be a Component of asthma or to emphysema, it can be assessed by the volume difference between what exits the lung as determined by a spirometer and the volume compressed as measured by the plethysmography. Method : To investigate whether volume difference between slow and forced vital Capacity(SVC-FVC) by spirometry may be used as a surrogate index of airway collapse, we examined pulmonary function parameters before and after bronchodilator agent inhalation by spirometry and body plethysmography in 20 cases of patients with evidence of airflow limitation(chronic obstructive pulmonary disease 12 cases, stable bronchial asthma 7 cases, combined chronic obstructive pulmonary disease with asthma 1 case) and 20 cases of normal subjects without evidence of airflow limitation referred to the Pusan National University Hospital pulmonary function laboratory from January 1995 to July 1995 prospectively. Results : 1) Average and standard deviation of age, height, weight of patients with airflow limitation was $58.3{\pm}7.24$(yr), $166{\pm}8.0$(cm), $59.0{\pm}9.9$(kg) and those of normal subjects was $56.3{\pm}12.47$(yr), $165.9{\pm}6.9$(cm), $64.4{\pm}10.4$(kg), respectively. The differences of physical characteristics of both group were not significant statistically and male to female ratio was 14:6 in both groups. 2) The difference between slow vital capacity and forced vital capacity was $395{\pm}317ml$ in patients group and $154{\pm}176ml$ in normal group and there was statistically significance between two groups(p<0.05). Sensitivity and specificity were most higher when the cut-off value was 208ml. 3) After bronchodilator inhalation, reversible airway obstructions were shown in 16 cases of patients group, 7 cases of control group(p<0.05) by spirometry or body plethysmography d the differences of slow vital capacity and forced vital capacity in bronchodilator response group and nonresponse group were $300.4{\pm}306ml$, $144.7{\pm}180ml$ and this difference was statistically significant. 4) The difference between slow vital capacity and forced vital capacity before bronchodilator inhalation was correlated with airway resistance before bronchodilator(r=0.307 p=0.05), and the difference between slow vital capacity and forced vital capacity after bronchodilator was correlated with difference between slow vital capacity and forced vital capacity(r=0.559 p=0.0002), thoracic gas volume(r=0.488 p=0.002) before bronchodilator and airway resistance(r=0.583 p=0.0001), thoracic gas volume(r=0.375 p=0.0170) after bronchodilator, respectively. 5) The difference between slow vital capacity and forced vital capacity in smokers and nonsmokers was $257.5{\pm}303ml$, $277.5{\pm}276ml$, respectively and this difference did not reach statistical significance(p>0.05). Conclusion : The difference between slow vital capacity and forced vital capacity by spirometry may be useful for the detection of collapsible airway and may help decision making of therapeutic plans.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.3
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• pp.220-226
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• 2017

Dopamine (DA) and serotonin (5-Hydroxytryptamine, 5-HT) are neurotransmitters and hormones that exist in small amounts but have important role in the body. Serum and 24-hour urine are used as specimens, and are usually examined by HPLC-MS. In this study, we tried to detect DA and 5-HT by competitive ELISA using antigen-antibody (Ab) reaction. After immobilizing $5{\mu}g/mL$ BSA conjugate on a 96-well surface, hormone and primary Ab, which are respectively diluted to different concentrations, were treated. Then, HRP-conjugated secondary Ab and TMB were added to measure absorbance. The regression equation and $R^2$ value were calculated based on absorbance, and sensitivity of Ab to hormone as well as the correlation between hormone concentration and absorbance were determined. In DA ELISA, $R^2$, the correlation between the concentration of hormone and absorbance, was the highest by 0.91 when anti-dopamine Ab was diluted 6,000 times and 7,000 times. In 5-HT ELISA, $R^2$ was bigger than 0.90 in every concentration except 3,000 times and 6,000 times. Both DA and 5-HT were not effectively detected at low concentrations (less than $1.0{\times}10^{-7}M$); and because reference value of serum DA is lower than this, HPLC-MS was required to detect serum DA. However, competitive ELISA may be effective in detecting 24-hour urine DA, serum, and 24-hour 5-HT. Further studies are needed to detect hormones more accurately at lower concentrations.

• Tuberculosis and Respiratory Diseases
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• v.45 no.3
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• pp.519-528
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• 1998

Background: Diagnosis of pulmonary tuberculosis is not easy when the sputum smear for Mycobacterium tuberculosis(M. Tb) is negative. We evaluated the clinical utility of polymerase chain reaction(PCR) for detecting M. Tb in bronchoalveolar lavage(BAL) samples. Methods: We recruited 84 patients whose sputum smear for M. Tb were negative or not available due to no production of sputum. We performed bronchoalveolar lavage for acid-fast stain, culture of mycobacteria, and PCR assay of BAL fluid. We analyzed the results of microbiologic examination. Results: The sensitivity of BAL fluid smear, culture, and PCR were 20%, 38%, and 40%, respectively. The specificity of BAL fluid PCR was 95%. The positive predictive value of PCR was 89%. The smear of BAL fluid was positive in 17%. The PCR of BAL fluid was the only diagnostic test in 17%. Therefore, the BAL fluid analysis including smear and PCR was diagnostic in 34 % within 24 hours. The BAL fluid analysis including smear, PCR, and culture was diagnostic in 55% within 2 month. Conclusion: The BAL fluid PCR was valuable method in the diagnosis of pulmonary tuberculosis in patients whose sputa were not available or reveal negative smear.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.94-102
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• 1997

Purpose: There have been some efforts to diagnose intracranial aneurysm through a non-invasive method using MRA, although the process may be difficult when the lesion is less than 3mm. The present study prospectively compares the results of high resolution, fast speed slice interpolation MRA and DSA thereby examing the potentiality of primary non-invasive screening test. Materials and Methods: A total of 26 cerebral aneurysm lesions from 14 patients with subarachnoid hemorrhage from ruptured aneurysm (RA) and 5 patients with unruptured aneurysm(UA). In all subjects, MRA was taken to confirm the vessel of origin, definition of aneurysm neck and the relationship of the aneurysm to nearby small vessels, and the results were compared with the results of DSA. The images were obtained with 1.5T superconductive machine (Vision, Siemens, Erlangen, Germany) on 4 slabs of MRA using slice interpolation. The settings include TR/TE/FA=30/6.4/25, matrix $160{\times}512$, FOV $150{\times}200$, 7minutes 42 seconds of scan time, effective thickness of 0.7 mm and an entire thickness of 102. 2mm. The images included structures from foramen magnum to A3 portion of anterior cerebral artery. MIP was used for the image analysis, and multiplanar reconstruction (MPR) technique was used in cases of intracranial aneurysm. Results: A total of 26 intracranial aneurysm lesions from 19 patients with 2 patients having 3 lesion, 3 patients having 2 lesions and the rest of 14 patients having 1 lesion each were examined. Among those, 14 were RA and 12 were UA. Eight lesions were less than 2mm in size, 9 lesions were 3-5mm, 7 were 6-9mm and 2 were larger than IOmm. On initial exams, 25 out of 26 aneurysm lesions were detected in either MRA or DSA showing 96% sensitivity. Specificity cannot be estimated since there was no true negative of false positive findings. When MRA and MPR were used concurrently for the confirmation of size and shape, the results were equivalent to those of DSA, while in the confirmation of aneurysm neck and parent vessels, the concurrent use of MRA and MPR was far superior to the sole use of either MRA or DSA. Conclusion: High resolution MRA using slice interpolation technique showed equal results as those of DSA for the detection of intracranial aneurysm, and may be used as a primary non-invasive screening test in the future.