Sungchul Seo

Development and evaluation of antimicrobial activated carbon fiber filters using Sophora flavescens nanoparticles

Activated carbon fiber (ACF) filters have a wide range of applications, including air purification, dehumidification, and water purification, due to their large specific surface area, high adsorption capacity and rate, and specific surface reactivity. However, when airborne microorganisms such as bacteria and fungi adhere to the carbon substrate, ACF filters can become a source of microbial contamination, and their filter efficacy declines. Antimicrobial treatments are a promising means of preventing ACF bio-contamination. In this study, we demonstrate the use of Sophora flavescens in antimicrobial nanoparticles coated onto ACF filters. The particles were prepared using an aerosol process consisting of nebulization-thermal drying and particle deposition. The extract from S. flavescens is an effective, natural antimicrobial agent that exhibits antibacterial activity against various pathogens. The efficiency of Staphylococcus epidermidis inactivation increased with the concentration of S. flavescens nanoparticles in the ACF filter coating. The gas adsorption efficiency of the coated antimicrobial ACF filters was also evaluated using toluene. The toluene-removal capacity of the ACF filters remained unchanged while the antimicrobial activity was over 90% for some nanoparticle concentrations. Our results provide a scientific basis for controlling both bioaerosol and gaseous pollutants using antimicrobial ACF filters coated with S. flavescens nanoparticles.

The level of submicron fungal fragments in homes with asthmatic children

OBJECTIVES Much scientific evidence indicates a positive association between moldy environments and respiratory illnesses and/or symptoms (e.g., asthma). Recently, submicron fungal fragments (<1.0 μm) have been suggested as a potential contributor to adverse health effects due to their biological composition (e.g., antigens, mycotoxins, and (1,3)-β-D-glucan) as well as their small size. However, the contribution of exposure to fine fungal particles on adverse health outcomes has been poorly characterized, particularly in homes with asthmatic children. We characterized the airborne level of smaller-sized fungal particles between homes with and without asthmatic children. METHODS We visited 29 homes with (n=15) and without (n=14) an asthmatic child and sampled submicron fungal fragments in a living room and child׳s bedroom, along with outdoor sampling, using the NIOSH two-stage sampler. (1,3)-β-D-glucan of fungal fragments analyzed by Limulus Amebocyte lysate assay (LAL) was used for quantifying their exposure. RESULTS Overall, the geometric mean (GM) concentration of (1,3)-β-D-glucan in submicron fungal fragments in indoor air was two-fold higher in homes with asthmatic children (50.9 pg/m(3)) compared to homes with non-asthmatic children (26.7 pg/m(3)) (P<0.001). The GM concentration of these particles in child׳s bedroom in homes with an asthmatic child (66.1 pg/m(3)) was about three times higher than that in homes with non-asthmatic children (23.0 pg/m(3)) (P<0.001). The relative humidity had a negative correlation with the concentration of (1,3)-β-D-glucan in submicron fungal fragments (Pearson coefficient=-0.257, P=0.046). CONCLUSIONS Our findings indicate that homes with asthmatic children have a higher concentration of submicron fungal fragments compared to homes with non-asthmatic children. A greater exposure to smaller-sized fungal particles may occur in homes with an asthmatic child as relative humidity decreases. The very careful control of relative humidity in indoor air is necessary for reducing exposure to fine fungal particles and inhibiting the growth of microorganisms in homes with allergic diseases.

GIS-based Association Between PM10 and Allergic Diseases in Seoul: Implications for Health and Environmental Policy.

Purpose The role of PM10 in the development of allergic diseases remains controversial among epidemiological studies, partly due to the inability to control for spatial variations in large-scale risk factors. This study aims to investigate spatial correspondence between the level of PM10 and allergic diseases at the sub-district level in Seoul, Korea, in order to evaluate whether the impact of PM10 is observable and spatially varies across the subdistricts. Methods PM10 measurements at 25 monitoring stations in the city were interpolated to 424 sub-districts where annual inpatient and outpatient count data for 3 types of allergic diseases (atopic dermatitis, asthma, and allergic rhinitis) were collected. We estimated multiple ordinary least square regression models to examine the association of the PM10 level with each of the allergic diseases, controlling for various sub-district level covariates. Geographically weighted regression (GWR) models were conducted to evaluate how the impact of PM10 varies across the sub-districts. Results PM10 was found to be a significant predictor of atopic dermatitis patient count (P<0.01), with greater association when spatially interpolated at the sub-district level. No significant effect of PM10 was observed on allergic rhinitis and asthma when socioeconomic factors were controlled for. GWR models revealed spatial variation of PM10 effects on atopic dermatitis across the sub-districts in Seoul. The relationship of PM10 levels to atopic dermatitis patient counts is found to be significant only in the Gangbuk region (P<0.01), along with other covariates including average land value, poverty rate, level of education and apartment rate (P<0.01). Conclusions Our findings imply that PM10 effects on allergic diseases might not be consistent throughout Seoul. GIS-based spatial modeling techniques could play a role in evaluating spatial variation of air pollution impacts on allergic diseases at the sub-district level, which could provide valuable guidelines for environmental and public health policymakers.

Antimicrobial durability of air filters coated with airborne Sophora flavescens nanoparticles

Airborne biological particles containing viruses, bacteria, and/or fungi can be toxic and cause infections and allergy symptoms. Recently, natural materials such as tea tree oil and Sophora flavescens have shown promising antimicrobial activity when applied as air filter media. Although many of these studies demonstrated excellent antimicrobial efficacy, only a few of them considered external environmental effects such as the surrounding humidity, temperature, and natural degradation of chemicals, all of which can affect the antimicrobial performance of these natural materials. In this study, we investigated the antimicrobial durability of air filters containing airborne nanoparticles from S. flavescens for 5 months. Antimicrobial tests and quantitative chemical analyses were performed every 30 days. Morphological changes in the nanoparticles were also evaluated by scanning electron microscopy. The major antimicrobial compounds remained stable and active for ~90 days at room temperature. After about 90 days, the quantities of major antimicrobial compounds decreased noticeably with a consequent decrease in antimicrobial activity. These results are promising for the implementation of new technologies using natural antimicrobial products and provide useful information regarding the average life expectancy of antimicrobial filters using nanoparticles of S. flavescens.

Comparison of diverse estimation methods for personal exposure to air pollutants and associations with allergic symptoms: The Allergy & Gene-Environment Link (ANGEL) study

We estimated the exposure to ambient air pollutants and analyzed the associations with allergic diseases. We enrolled 177 children with atopic dermatitis (AD) and 70 asthmatic adults living in Seoul Metropolitan Area, Korea, and followed for 17months between August 2013 and December 2014. Parents or patients recorded symptom scores on a daily basis. Exposure to particulate matter with a diameter <10μm (PM10) and nitrogen dioxide (NO2) was estimated in four different ways in each individual, using the AQ1 (measurements from the nearest air quality monitoring station to residential houses), AQ2 (measurements modified from AQ1 with the indoor level of air pollutants and time activity of each individual), AQ1-DI, and AQ2-DI (measurements modified from AQ1 and AQ2, respectively, with daily inhalation intakes of air pollutants). A generalized linear mixed model (GLMM) was used to analyze the associations between exposure metrics and clinical symptoms after adjusting for ambient temperature and humidity, age, season, gender, and time trend. The exposure metrics for PM10 and NO2 showed different distributions. Symptoms of AD and asthma were positively associated with exposure to PM10, but not NO2, in all exposure metrics. The effect size of PM10 exposure on asthma symptoms was slightly greater in metrics with inhalation capacity (AQ-DIs) than in those without (AQs). This pattern was not observed in AD. Exposure to PM10 is associated with symptom aggravation in childhood AD and adult asthma. Different exposure estimates may be used to evaluate the impact of air pollution on different allergic diseases.

Evaluation of Effectiveness for an Atopy Prevention Program Operated by a Local Government

Objectives: We evaluated the effects of an allergy control program on children with atopic dermatitis (AD) in five schools located within Gyeonggi-do. Methods: Based on the results of the 12-month prevalence of AD symptoms from an International Study of Asthma and Allergies in Childhood (ISAAC) ques...

Salmonella typhimurium with γ-radiation induced H2AX phosphorylation and apoptosis in melanoma

To investigate the combinatorial effects using Salmonella and γ-radiation, the Salmonella typhimurium infection in combination with γ-radiation was investigated on melanoma. We showed that ROS expression and H2AX phosphorylation increased during stress by γ-radiation irrespective of Salmonella infection, inducing apoptosis by caspase-3 and bcl2 in tumor cells. In addition, tumor growth was suppressed by this combinatory therapy suggesting candidates for radiation therapy against melanoma.