• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.313-322
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• 2021

Purpose: To find diagnostic image features, to compare diagnostic performance of multiphase CT versus gadoxetic acid disodium-enhanced MRI (GAD-MRI), and to evaluate the impact of analyzing Liver Imaging Reporting and Data System (LI-RADS) imaging features, for distinguishing combined hepatocellular-cholangiocarcinoma (CHC) from hepatocellular carcinoma (HCC). Materials and Methods: Ninety-six patients with pathologically proven CHC (n = 48) or HCC (n = 48), diagnosed June 2008 to May 2018 were retrospectively analyzed in random order by three radiologists with different experience levels. In the first analysis, the readers independently determined the probability of CHC based on their own knowledge and experiences. In the second analysis, they evaluated imaging features defined in LI-RADS 2018. Area under the curve (AUC) values for CHC diagnosis were compared between CT and MRI, and between the first and second analyses. Interobserver agreement was assessed using Cohen's weighted κ values. Results: Targetoid LR-M image features showed better specificities and positive predictive values (PPV) than the others. Among them, rim arterial phase hyperenhancement had the highest specificity and PPV. Average sensitivity, specificity, and AUC values were higher for MRI than for CT in both the first (P = 0.008, 0.005, 0.002, respectively) and second (P = 0.017, 0.026, 0.036) analyses. Interobserver agreements were higher for MRI in both analyses (κ = 0.307 for CT, κ = 0.332 for MRI in the first analysis; κ = 0.467 for CT, κ = 0.531 for MRI in the second analysis), with greater agreement in the second analysis for both CT (P = 0.001) and MRI (P < 0.001). Conclusion: Rim arterial phase hyperenhancement on GAD-MRI can be a good indicator suggesting CHC more than HCC. GAD-MRI may provide greater accuracy than CT for distinguishing CHC from HCC. Interobserver agreement can be improved for both CT and MRI by analyzing LI-RADS imaging features.

• Journal of Soil and Groundwater Environment
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• v.29 no.5
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• pp.27-36
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• 2024

This study, estimates the predicted no effect concentration (PNEC) for the protection of organisms in aquatic and soil environments, considering the mode of action of Perfluorooctanesulfonic acid (PFOS). PNECs were derived using the species sensitivity distribution (SSD) approach to estimate the hazardous concentration for 5% of species (HC5), with applying assessment factors. Chronic toxicity data on PFOS were collected through the USEPA's ECOTOX database and literature reviews, and classified by toxicity endpoints. PNECs were then derived for each of seven toxicity endpoints that met the criteria for SSD fitting. For aquatic organisms, the PNEC for PFOS, based on all available chronic toxicity data, was determined to be 0.53 ㎍/L. The PNECs for development, genetics, enzymes, growth, reproduction, population, and biochemical biomarkers were 0.28, 0.43, 0.83, 0.90, 2.17, 111.17, and 3.53 ㎍/L, respectively. The lowest PNEC was observed when the toxic endpoint was set as development, which is considered to be due to the mode of action of PFOS, known to cause developmental toxicity by disrupting the endocrine system of organisms. For soil organisms, toxicity data were insufficient to estimate PNECs for individual endpoints, so all available data were used to estimate a PNEC of 0.75 mg/kg. Estimating PNECs that consider the mode of action of contaminants is expected to reduce the likelihood of underestimating protection levels for environmental contaminants. Additionally, this study highlights the need for ecotoxicological assessments for individual toxicity endpoints of emerging contaminants, including Per- and polyfluoroalkyl substances, in soil environments.

• Tuberculosis and Respiratory Diseases
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• v.47 no.5
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• pp.586-597
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• 1999

Background: Many diagnostic tests have developed to diagnose tuberculosis and other mycobacterial diseases but the diagnosis of tuberculosis relies largely on radiological findings and acid-fast staining of sputum and/or culture. Recently, new serologic diagnostic methods, which are safe and easy to use have been introduced into Korea. In this study, the usefulness of serologic diagnosis for tuberculosis and the disease pattern induced variation of the test were evaluated. Methods: Serological assay was performed upon 108 patients with two test kits, the ICT tuberculosis and the BioSign$^{TM}$TB, which are based upon a rapid immunochromatographic assay technique, capable of being interpreted within 15 minutes. The case groups consisted of 61 patients with active pulmonary tuberculosis(36 patients), extrapulmonary tuberculosis(3 patients), or both(22 patients). Control groups consisted of 47 patients with inactive old pulmonary tuberculosis(17 patients), nontuberculous pulmonary disease(16 patients) and nonpulmonary cardiac disease(14 patients). Results : The diagnostic sensitivity, specificity, positive predictive value(PPV) and negative predictive value(NPV) of the ICT tuberculosis were 64.3%, 91.5%, 90.0% and 68.3% respectively. The diagnostic sensitivity, specificity, PPV and NPV of the BioSign$^{TM}$TB were 76.5%, 95.3%, 94.1 % and 78.8% respectively. Differences in sensitivity were not significant between patients with previous history of tuberculosis or patients without prior history of tuberculosis. The ICT tuberculosis test showed higher sensitivity in pulmonary tuberculosis patients(76.5%) than extrapulmonary tuberculosis patients(33.3%). There was no difference in sensitivity between patients with or without cavitary lesion by chest X-ray. Conclusion: Considering high specificity and PPV, serologic diagnosis using a rapid immunochromatographic assay device is another helpful diagnostic method in the diagnosis of tuberculosis, when combined with previous diagnostic methods such as chest X-ray, microbiologic study but it has limitation in terms of confirming the diagnosis for tuberculosis as the only diagnostic method because of relatively low sensitivity and NPV.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7607-7611
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• 2013

Background: Cervical cancer continues to be a major problem in Bangladesh with approximately 18,000 new cases annually of which over 10,000 women die from it. Visual inspection of the cervix after 3-5% acetic acid (VIA) application is a simple and easy to learn method for cervical cancer screening, although cytology-based screening is more often applied in developed countries where it has successfully reduced the prevalence of cervical cancer. Objective: To compare the efficacy of VIA and cytology-based primary methods for cervical cancer screening in Bangladesh. Materials and Methods: This hospital based comparative study was conducted at the VIA centre and Colposcopy Clinic of Bangabandhu Sheikh Mujib Medical University (BSMMU) from October 2008 to October 2010. Results: Among 650 women, 74 (11.4%) were VIA+ve and 8 (1.2%) had abnormalities in their Pap smear reports. During colposcopy, 38 (7.7%) women had different grades of CIN and 4 (0.6%) had cervical cancer. The gold standard histology findings proved 20 women had CIN I, 14 had CIN II/II and 4 had cervical cancer. Among the 38 histology diagnosed abnormalities, VIA test could identify 30 abnormalities including two cervical cancers. However, Pap smear could detect only 8 cases of histological abnormalities (2 low grade and 6 had high grade lesion) and it missed all the cervical cancer cases. The sensitivity and specificity of VIA were 88.9% and 52.1%. The positive predictive value (PPV) and negative predictive value (NPV) were 41.0%, and 92.6% respectively. Moreover, the sensitivity, specificity, PPV and NPV of Pap smear were 33.3%, 95.8%, 75.0% and 79.3%, respectively. Conclusions: VIA test should be used as the primary screening tool even with its low sensitivity and specificity in low resource countries like Bangladesh. False positive results may be greater, but overtreatment can be minimized by colposcopy evaluation of the VIA positive women.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1626-1632
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• 2018

In this paper, we describe the fabrication and characterization of a hydrogen peroxide ($H_2O_2$) sensor based on palladium and copper (PdCu) electroplated laser induced graphene (LIG) electrodes. $CO_2$ laser was used to form LIG electrodes on a PI film. This fabrication method allows simple control of the LIG electrode size and shape. The PdCu was electrochemically deposited on the LIG electrodes to improve the electrocatalytic reaction with $H_2O_2$. The electrochemical performance of this sensor was evaluated in terms of selectivity, sensitivity, and linearity. The physical characterization of this sensor was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which confirmed that PdCu was formed on the laser induced graphene electrode. In order to increase the sensor sensitivity, the Pd:Cu ratio of the electroplated PdCu was varied to five different values and the condition of highest amperometric current at an identical of $H_2O_2$ concentration was chosen among them. The resulting amperometric current was highest when the ratio of Pd:Cu was 7:3 and this Pd;Cu ratio was employed in the sensor fabrication. The fabricated PdCu/LIG electrode based $H_2O_2$ sensor exhibited a sensitivity of $139.4{\mu}A/mM{\cdot}cm^2$, a broad linear range between 0 mM and 16 mM of $H_2O_2$ concentrations at applied potential of -0.15 V, and high reproducibility (RSD = 2.6%). The selectivity of the fabricated sensors was also evaluated by applying ascorbic acid, glucose, and lactose separately onto the sensor in order to see if the sensor ourput is affected by one of them and the sensor output was not affected. In conclusion, the proposed PdCu/LIG electrode based $H_2O_2$ sensor seems to be suitable $H_2O_2$ sensor in various applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.117-124
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• 2019

Vibrio cholerae is a very important pathogenic bacterium that has to be monitored in seafood and ships' ballast water. Various methods have been developed to identify this bacterium, yet these methods are time-consuming and have limitations for their sensitivity to detect contamination. The purpose of the present study was to develop a robust and reliable method for identifying V. cholerae. Peptide nucleic acid (PNA) probes were developed to use for PNA-based asymmetrical real-time PCR techniques. The toxigenic Cholera enterotoxin subunit B (ctxB) gene was selected as a target for detecting V. cholerae and the gene was synthesized as a positive template for conventional and real-time PCR. Real-time PCR primers and PNA probes were designed and standard curves were produced for the quantitative analysis. The selected PNA probes reacted specifically to V. cholerae without any ambiguity, even among closely related species, and the detection limit was 0.1 cfu/100 mL. Taken together, the PNA probes and asymmetrical qPCR methods developed in this present study could contribute to the rapid, accurate monitoring of V. cholerae in marine environments, and as well as in seafood and ships' ballast waters.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.360-365
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• 1992

Clinical isolates of 8 ofloxacin resistant Staphylococcus auresu (ORSA) were subjected to MIC test, Southern analysis on gyrA locus and nucleotide sequence analysis of 290 bp of gyrA gene (gyrA-290) spanning amino acid 26 to 121 in order to understand the mechanism of quinolone resistance in Staphylococcus aureus. ORSAs showed highlevel resistance against quinolones (8-250 fold increase of MICs) and also significant resistance agianst ${\beta}-lactams$ (2-32 fold increase of MICs). However, ORSs did not show any change in sensitivity agianst vancomycin. Southern analysis of ORSAs with HindIII, PstI and AluI revealed RFLPs on gyrA locus. In order to further analyze the gyrA gene, gyrA-290 was amplified by PCR and cloned to pTZ vector. Subsequent nucleic acid sequence analysis of gyrA-290 demonstrated a point mutation of C to T resulting amino acid change of Ser-84 to Leu-84 in all 8 ORSA strains. The substitution at 84th amino acid of tyrase A might confer one mechanism of high level quinolone resistance in Staphylococcus aureus.

• Analytical Science and Technology
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• v.19 no.6
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• pp.482-489
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• 2006

Two electrode-based lactate biosensor was prepared by immobilizing lactate oxidase (LOD) obtained from pediococcus species in a poly(vinyl alcohol). Hydrogen peroxide ($H_2O_2$) produced by the reaction of lactate and LOD was detected on the Pt-black that was electrochemically deposited on the Au electrode. Sensors fabricated with Pt-black deposited Au electrode provided a high current of $H_2O_2$ oxidation at a substantially lowered applied potential (+300 mV vs. Ag/AgCl), resulting in reduced interferences from easily oxidizable species such as ascorbic acid, acetaminophen, and uric acid. An outer membrane is formulated by adjusting water uptake of hydrophilic polyurethane (HPU). The sensor performance was evaluated in vitro with both flow-through arrangement and static mode. The sensor showed a linear range from 0.1 mM to about 9.0 mM in 0.05 M phosphate buffer (pH 7.6) containing 0.05 M NaCl. Storing the sensors prepared in this work at $4^{\circ}C$ buffer solution while not in use, they provided same electrochemical performance for more than 25 days.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.7
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• pp.941-946
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• 2001

The effects of various concentrations of saturated fatty acids (SFA; caprylic, capric and stearic acids) on the growth of the anaerobic fungus, Neocallimastix frontalis C5-1 isolated from the rumen of a Korean native goat were investigated. At higher concentrations of fatty acids (0.1%, w/v), the addition of SFA strongly decreased filter paper (FP) cellulose digestion and polysaccharide-degrading enzyme activity. The sensitivity of the rumen anaerobic fungus to the added fatty acids increased in the following order: caprylic ($C_{8:0}$)>capric($C_{10:0}$)>stearic($C_{18:0}$) acid, although stearic acid had no significant (p<0.05) inhibitory effects at any of the concentrations tested. However, the addition of SFA at lower concentrations (0.01 and 0.001% levels), did not inhibit FP cellulose degradation and enzyme activity. Furthermore, although these parameters were slightly stimulated by the addition of SFA, they were not statistically different from control values. This is the first report examining the effects of fatty acids on anaerobic gut fungi. We found that the lower levels of fatty acids used in this experiment were able to stimulate the growth and specific enzyme activities of rumen anaerobic fungi, whereas the higher levels of fatty acids were inhibitory with respect to fungal cellulolysis.

• Analytical Science and Technology
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• v.28 no.2
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• pp.98-105
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• 2015

The development of an enzymatic biosensor for dopamine determination based on multiwall carbon nanotubes (MWCNTs) and peroxidase obtained from the crude extract of burley tobacco (Nicotiana tabacum L.) was proposed. Peroxidase catalyzes the oxidation of dopamine to dopamine quinone. The influence on the response of analytical parameters of biosensors such as enzyme concentration, dopamine concentration, pH, and phosphate buffer solution concentration were investigated. The analytical parameters obtained, including sensitivity, linearity, and stability, were investigated. The proposed method for dopamine determination presented good selectivity even in the presence of uric acid and ascorbic acid. The sensor presented a higher response for dopamine in 0.010 M phosphate buffer at pH 6.50, with an applied potential of -0.15 V. The detection limit of the electrode was 2.7×10⁻⁶ M (S/N = 3) and the relative standard deviation of the measurements, which were repeated 10 times using 5.0×10⁻² M dopamine, was 1.3%.