• KSBB Journal
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• v.20 no.1 s.90
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• pp.60-65
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• 2005

The objective of this work was to evaluate a solid-state fermentation process for the practical production of arachidonic acid(AA) by Mortierella alpina ATCC 32222. In the present investigation, batch culture kinetics for both submerged- and solid-state fermentations was carried out at $25^{\circ}C$ to identify the relationship between growth and arachidonic acid (AA) production. Glucose and yeast extract were used in submerged fermentations by using flasks, while rice bran was used as a sole raw material in the other type of fermentations by using a series of Petri dishes. It was evident that a mixed-growth associated pattern existed between the two variables, irrespective of modes of fermentations. The effect of carbon to nitrogen (CfN) ratio on AA production in solid-state fermentation was studied in the range of 6.5 - 20. As a result, an optimum condition was found to be 6.5. Supplementary carbon source was not necessary to meet the optimum C/N ratio. Unlike the Previous results obtained by other researchers, a supplement of sodium glutamate up to $4\%$ (w/w) to the rice bran medium did not have a positive effect on the AA productivity. However, an increase in AA productivity was obtained with the rice bran medium supplemented with sesame oil.

• KSBB Journal
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• v.27 no.1
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• pp.67-74
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• 2012

In this study, the optimum conditions of fermentation were determined by isolating the microorganisms with the ability to bioconvert the Citrus peel flavonoid, and the effect of the fermented Citrus peel extract which was bioconverted on the oxidative damage of HIT-T15 cell was investigated. The Aureobasidium pullulans Y-12 was isolated and identified with the strains having bioconversion activity. The fermentation conditions for bioconversion activity were confirmed to be optimal when culturing for three days at $25^{\circ}C$, 150 rpm in a culture medium containing 5% Citrus peel power and 0.8% casitone. As a result of bioconversion, 32.8 mg/g and 21.5 mg/g of naringenin and hesperetin, which were aglycone flavones, were produced respectively. Also in the flavonoid content, it was confirmed that FCP produced 154.8 mg/g while CP produced 33.7 mg/g, thus producing more by approximately 4.6 times. As a result of treating FCP and CP after inducing the oxidative damage for HIT-T15 cell by treating the deoxy-D-ribose with $IC_{50}$ (38 mM) concentration, the surviving rate was recovered to 90% for FCP treatments in the 0.01 mg/mL concentration and for CP treatments in the 0.025 mg/mL concentration. Also in the insulin secretion rate, FCP treatments increased by 206% and CP treatments by 132% when treated in the 0.1 mg/mL concentration. As the bioconverted FCP can inhibit the oxidative damage of HIT-T15 cell in the low concentration, it was considered its usability as the functional material for prevention of the type 2 diabetes.

• KSBB Journal
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• v.22 no.6
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• pp.409-413
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• 2007

Polydiacetylene(PDA)-based sensors possess a number of properties that can be successfully applied for label-free detection system. PDA is one of the most attractive color-generating materials, with growing applications as sensors. Here we introduce various PDA-based devices, used as biosensor, chemosensor, thermosensor, and optoelectronics sensor. In general, PDA liposomes and films are closely packed and properly designed for polymerization via 1,4-addition reaction to form an ene-yne alternating polymer chain. PDA-based two/three dimensional structures have been used for colorimetric or fluorescent devices, sensing biological as well as chemical components. This color-generating material also present a very high charge carrier mobility, allowing its application as field-effect transistor (FET). The immobilized PDA structures or films have distinct advantages for the detection of low concentration target molecules over the aqueous solution-based detection systems. In the present review, reported detection methods by using various PDA structures are summarized with updated references.

• Journal of Life Science
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• v.31 no.6
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• pp.595-602
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• 2021

Human intestinal microbiota play an important role in the regulation of the host's metabolism. There is a close pathological and physiological interaction between dysbiosis of the intestinal microflora and obesity and metabolic syndrome. Akkermansia muciniphila, which was recently isolated from human feces, accounts for about 1-4% of the intestinal microbiota population. The use of A. muciniphila- derived external membrane protein Amuc_1100 and extracellular vesicles (EVs) could be a new strategy for the treatment of obesity. A. muciniphila is considered a next-generation probiotic (NGP) for the treatment of metabolic disorders, such as obesity. Faecalibacterium prausnitzii accounts for about 5% of the intestinal microbiota population in healthy adults and is an indicator of gut health. F. prausnitzii is a butyrate-producing bacterium, with anti-inflammatory effects, and is considered an NGP for the treatment of immune diseases and diabetes. Postbiotics are complex mixtures of metabolites contained in the cell supernatant secreted by probiotics. Parabiotics are microbial cells in which probiotics are inactivated. Paraprobiotics and postbiotics have many advantages over probiotics, such as clear chemical structures, safe dose parameters, and a long shelf life. Thus, they have the potential to replace probiotics. The most natural strategy to restore the imbalance of the intestinal ecosystem normally is to use NGPs among commensal bacteria in the gut. Therefore, it is necessary to develop new foods or drugs such as parabiotics and postbiotics using NGPs.

• Ecology and Resilient Infrastructure
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• v.9 no.2
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• pp.83-92
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• 2022

The 2020 summer extreme flood severely disturbed the riparian ecosystem of the Seomjin River. Some trees were killed by the flood impact, whereas others have recovered through epicormic regeneration after the disturbance. At the same time, several tree individuals newly germinated. This research aimed to explain the recovery of the riparian ecosystem by spatial proximity between each tree individual of different characteristics, such as "dead", "recovered", and "newly germinated". A spatial point pattern analysis based on K and g-functions revealed that the newly germinated trees and the existing trees were distributed in the spatially clumping patterns. However, further detailed analysis revealed that the new trees were statistically less attracted to the recovered trees than the dead trees, implying competitive interactions hidden in the facilitative interactions. Habitat amelioration by the existing trees positively affected the growth of the new trees, while "living" existing trees were competing with the new trees for resources. This research is expected to provide new knowledge in this era of rapid climate change, which likely induces stronger and more frequent natural disturbance than before. Environmental factors have been widely used for ecosystem modeling, but species interactions, represented by the relative spatial distribution of plant individuals, are also valuable factors explaining ecosystem dynamics.

• Journal of Life Science
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• v.33 no.2
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• pp.216-226
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• 2023

Since nylon 66, a polyamide resin, has been developed and applied to toothbrush bristles, plastic consumption has increased rapidly every year, along with the increase in the amount of plastic discarded. Among the various forms of plastic debris produced by the decomposition of plastics, microplastics with a size of less than 5 mm are widely distributed in the environment, which poses a threat not only to the environment but also to animals and humans. The pathway through which microplastics enter the human body is known as ingestion by water and food, inhalation from air, and skin contact. Microplastics introduced into the human body affect human health. Recently, food-related studies have begun to be reported among microplastics-related studies, and analyses of the presence of microplastics in processed foods, such as canned foods, dried seaweed, beverages, beer, milk, sugar, and honey, are underway. Here, we present trends in the production and consumption of plastics, the generation of microplastics, the route of human inflow and human risk, and the microplastics present in processed foods, which are limited but have recently been reported. Thus far, studies on microplastics and risk assessment in processed foods have been insufficient, but microplastics are gradually being recognized as a factor that affects the environment and food. Future studies are expected to have implications for regulations regarding microplastics present in processed foods.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.53-61
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• 2022

This study aimed to increase the targeting ability against PSMA in cell therapy using metabolic glycoengineering and biorthogonal chemistry and to visualize cell trafficking using PET imaging. Cellular membranes of THP-1 cells were decorated with azide(-N₃) using Ac₄ManNAz by metabolic glycoengineering. Engineered THP-1 cells were conjugated with DBCO-bearing fluorophore (ADIBO-Cy5.5) for 1 h at different concentrations and analyzed by confocal fluorescence microscopy and flow cytometry. For PSAM ligand conjugation to THP-1 cells, Ac₄ManNAz treated THP-1 cells were incubated with DBCO-PSMA ligand (ADIBO-GUL) at a final concentration with 100 µM for 1 h. To evaluate the effect on cell recognition, PSMA ligand conjugated THP-1 cells(as effectors) were co-cultured with PSMA positive 22RV1 (as target cells) at 3 : 1 a effector-to-target cell (E/T) ratio. The interaction between THP-1 and 22RV1 was monitored by confocal fluorescence microscopy. For preparing the radiolabeled THP-1, the cells were treated at the activity of ~ 740 kBq of [⁸⁹Zr]Zr(oxinate)₄/5 × 10⁶ cells. Radiolabeled cells were analyzed for determination of cell-associated radioactivity by gamma counting and viability using MTS assay. In the cytotoxicity assay, THP-1 cells did not have any cytotoxicity even when the Ac₄ManNAz concentration was 100 µM. In confocal microscopy and flow cytometry, THP-1 cells were efficiently labeled ADIBO-Cy5.5 in a dose-dependent manner, and the dose of 100 µM was the optimal concentration for the following experiments. The clusters of PSMA ligand-conjugated THP-1 cells and 22RV1 cells were identified, indicating cell-cell recognition over the cell surface between two types of cells. Cell radiolabeling efficiency was 54.5 ± 17.8%. THP-1 labeled with 0.09 ± 0.03 Bq/cell showed no significant cytotoxicity compared to unlabeled THP-1 up to 7 days. We successfully demonstrated that Ac₄ManNAz treated cells were efficiently conjugated with ADIBO-GUL for preparing the PSMA-targeting cells, and [⁸⁹Zr]Zr(oxinate)₄ could be used to label cells without toxicity. It suggested that PSMA-ligand conjugated cell therapy could be improved cell targeting and be monitored by PET imaging.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.135-142
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• 2023

A various technology of remote sensing and image analysis are applied to study landscape changes and their influencing factors in stream corridors. We developed a method to detect landscape changes over time by calculating the optical index using multispectral images taken from satellites at various time points, calculating the threshold to delineate the boundaries of water bodies, and creating binarized maps into land and water areas. This method was applied to the upstream reach of the weirs in the Geumgang River to track changes in the sandbar formed by the opening of the weir gate. First, we collected multispectral images with a resolution of 10 m × 10 m taken from the Sentinel-2 satellite at various times before and after the opening of the dam in the Geumgang River. The normalized difference water index (NDWI) was calculated using the green light and near-infrared bands from the collected images. The Otsu's threshold of NDWI calculated to delineate the boundary of the water body ranged from -0.0573 to 0.1367. The boundary of the water area determined by remote sensing matched the boundary in the actual image. A map binarized into water and land areas was created using NDWI and the Otsu's threshold. According to these results of the developed method, it was estimated that a total of 379.7 ha of new sandbar was formed by opening the three weir floodgates from 2017 to 2021 in the longitudinal range from Baekje Weir to Daecheong Dam on the Geumgang River. The landscape detection method developed in this study is evaluated as a useful method that can obtain objective results with few resources over a wide spatial and temporal range.

• Journal of Marine Bioscience and Biotechnology
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• v.15 no.2
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• pp.41-48
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• 2023

The objective of the present study was to improve the biomass productivity of newly isolated freshwater green microalga Parachlorella sp. This was accomplished by culture conditions optimization, including CO₂ concentration, superficial gas velocity, and light intensity, in 0.5 L bubble column photobioreactors. The supplied CO₂ concentration and gas velocity varied from 0.032% (air) to 10% and 0.02 m/s - 0.11 m/s, respectively, to evaluate their effects on growth kinetics. Next, to maximize the production rate of Parachlorella sp., a lumostatic operation based on a specific light uptake rate (q_e) was applied. From these results, the optimal CO₂ concentration in the supplied gas and the gas velocity were determined to be 5% and 0.064 m/s, respectively. For the lumostatic operation at 10.2 µmol/g/s, biomass productivity and photon yield showed significant increases of 83% and 66%, respectively, relative to cultures under constant light intensity. These results indicate that the biomass productivity of Parachlorella sp. can be improved by optimizing gas properties and light control as cell concentrations vary over time.

• Korean Journal of Radiology
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• v.24 no.6
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• pp.529-540
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• 2023

Objective: To compare the diagnostic performance and clinical outcomes of 2-mSv computed tomography (CT) and conventional-dose CT (CDCT), following radiology residents' interpretation of CT examinations for suspected appendicitis. Materials and Methods: Altogether, 3074 patients with suspected appendicitis aged 15-44 years (28 ± 9 years, 1672 females) from 20 hospitals were randomly assigned to the 2-mSv CT (n = 1535) or CDCT (n = 1539) groups in a pragmatic trial from December 2013 and August 2016. Overall, 107 radiology residents participated in the trial as readers in the form of daily practice after online training for 2-mSv CT. They made preliminary CT reports, which were later finalized by attending radiologists via addendum reports, for 640 and 657 patients in the 2-mSv CT and CDCT groups, respectively. We compared the diagnostic performance of the residents, discrepancies between preliminary and addendum reports, and clinical outcomes between the two groups. Results: Patient characteristics were similar between the 640 and 657 patients. Residents' diagnostic performance was not significantly different between the 2-mSv CT and CDCT groups, with a sensitivity of 96.0% and 97.1%, respectively (difference [95% confidence interval {CI}], -1.1% [-4.9%, 2.6%]; P = 0.69) and specificity of 93.2% and 93.1%, respectively (0.1% [-3.6%, 3.7%]; P > 0.99). The 2-mSv CT and CDCT groups did not significantly differ in discrepancies between the preliminary and addendum reports regarding the presence of appendicitis (3.3% vs. 5.2%; -1.9% [-4.2%, 0.4%]; P = 0.12) and alternative diagnosis (5.5% vs. 6.4%; -0.9% [-3.6%, 1.8%]; P = 0.56). The rates of perforated appendicitis (12.0% vs. 12.6%; -0.6% [-4.3%, 3.1%]; P = 0.81) and negative appendectomies (1.9% vs. 1.1%; 0.8% [-0.7%, 2.3%]; P = 0.33) were not significantly different between the two groups. Conclusion: Diagnostic performance and clinical outcomes were not significantly different between the 2-mSv CT and CDCT groups following radiology residents' CT readings for suspected appendicitis.