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In this study, we investigated the photochemical release of dissolved organic matter (DOM) from the particulate organic matter (POM) of soil and litter leaves (broad leaves; coniferous leaves) and compared the releasing characteristics of the DOM using UV-visible and fluorescence spectroscopy. The disinfection by-product formation potential (DBPFP) of the released DOM was also examined. Additional dissolved organic carbon (DOC) was released by UV irradiation for all POM sources (10.58 ± 2.7 mg-C L−1 g−1 for BL, 8.32 ± 2.6 mg-C L−1 g−1 for CL, and 0.20 ± 0.1 mg-C L−1 g−1 for soil). The excitation-emission matrix combined with parallel factor analysis results showed that the photo-released DOM from soil was mainly humic-like components (C1, C3) produced by photodesorption, resulting in high trihalomethane formation potential, while protein-like component (C2) was the major component of the photodissolved DOM from litter leaves, resulting in high haloaceticacid formation potential. Further, DBPFP from soil and litter leaves showed high correlation with humic-like components (C1+C3) and SUVA254, respectively. In conclusion, this study demonstrates that significant amounts of DOM could be released from POM under UV irradiation, although the characteristics and DBP formation of the photo-released DOM were highly dependent upon the POM source.

Stem cells can differentiate into various body tissues and organs and thus are considered as promising tools for cell therapy and tissue engineering. Early passage stem cells have high differentiation ability compared to late passage stem cells. Thus, it is important to use early passage stem cells in cell therapy. Here, we investigated whether cell migration could be used to compare young and senescent cells. We used ‘electrotaxis’ where cells under electric treatment move towards the anode or cathode. Without an electric stimulus, stem cells moved randomly. However, under a direct electric current, the cells moved with directionality. Under stimulation with a direct electric current, early passage stem cells moved towards the anode; when the cells became senescent with increasing passages, the percentage of cells migrating to the anode decreased. These results suggest that the behavior of stem cells under the influence of a direct electric current is also related to their passage number. Therefore, electrotaxis migration analysis can be used to distinguish between young cell and senescent cells. Keywords: Stem cell, Directional migration, Electrotaxis, Senescence

The principle of photodynamic treatment (PDT) involves the administration of photosensitizer (PS) at diseased tissues, followed by light irradiation to produce reactive oxygen species (ROS). In cells, a moderate increase in ROS plays an important role as signaling molecule to promote cell proliferation, whereas a severe increase of ROS causes cell damage. Previous studies have shown that low levels of ROS stimulate cell growth through PS drugs-treating PDT and nonthermal plasma treatment. However, these methods have side effects which are associated with low tissue selectivity and remaining of PS residues. To overcome such shortcomings, we designed hematoporphyrin-incorporated polyurethane (PU) film induced generation of extracellular ROS with singlet oxygen and free radicals. The film can easily control ROS production rate by regulating several parameters including light dose, PS dose. Also, its use facilitates targeted delivery of ROS to the specific lesion. Our study demonstrated that extracellular ROS could induce the formation of intracellular ROS. In vascular endothelial cells, a moderated increase in intracellular ROS also stimulated cell proliferation and cell cycle progression by accurate control of optimum levels of ROS with hematoporphyrin-incorporated polymer films. This modulation of cellular growth is expected to be an effective strategy for the design of next-generation PDT.

Heavy storm events may increase the amount of organic matter in runoff from forested watersheds as well as the relation of dissolved to particulate organic matter. This study evaluated the effects of monsoon storm events on the runoff fluxes and on the composition of dissolved (3–N fluxes in runoff increased linearly with discharge pointing to changing flow paths from deeper to upper soil layers at high discharge, whereas nonlinear responses of POC and PON fluxes were observed likely due to the origin of particulate matter from the erosion of mineral soil along the stream benches. The integrated C and N fluxes in runoff over the 2-month study period were in the order of DOC > POC and NO3–N > DON > PON. The integrated DOC fluxes in runoff during the study period were much larger at the deciduous watershed (16 kg C ha−1) than at the mixed watershed (7 kg C ha−1), while the integrated NO3–N fluxes were higher at the mixed watershed (5.2 kg N ha−1) than at the deciduous watershed (2.9 kg N ha−1). The latter suggests a larger N uptake by deciduous trees. Integrated fluxes of POC and PON were similar at both watersheds. The composition of organic matter in soils and runoff indicates that the contribution of near-surface flow to runoff was larger at the deciduous than at the mixed watershed. Our results demonstrate different responses of particulate and dissolved C and N in runoff to storm events as a combined effect of tree species composition and watershed specific flow paths.

The polarization of the Golgi apparatus is an important phenomenon in the directional migration of many types of cells, including fluid shear stress enhanced infiltration of cells into scaffolds. Fourier transform infrared (FT-IR) spectroscopy would be a potential tool to study cell infiltration into scaffolds because this technique has simple, reproducible, non-destructive characteristics. Here, we investigated the effect of Golgi polarization on the directional migration and infiltration of human mesenchymal stem cells (hMSCs) into poly(lactic-co-glycolic acid) (PLGA) scaffolds by fluid shear stress. The cell infiltration into scaffolds by fluid shear stress was observed by immunofluorescence and FT-IR. 2 μM of Brefeldin A (BFA) inhibited the reorganization of Golgi polarization in hMSCs. The blocking of Golgi reorganization by BFA caused the suppression of directional migration and infiltration into PLGA scaffolds induced by 8 dyne/cm2 of fluid shear stress condition. In this study, we investig...

This study compared and analyzed the tooth brushing time per day and dental caries in 1-13-year-old children in the stage of the completion of their permanent teeth based on the 6th primitive at data of objective National Health Nutrition Survey. The results show a meaningful difference between the DMFT and dental caries experience. In particular, the group with a lower toothbrushing rate after lunch generally have a higher incidence of dental caries.

Despite the growing attention to the effects of hydrological precipitation on organic carbon export along the continuum land-river-ocean, limited effort has been made to understand the export and the reactivity of particulate organic carbon (POC) compared to those of dissolved organic carbon (DOC). Yet, further understanding of the controlling mechanisms on the export of particulate organic matter (POM) from terrestrial systems is fundamental. In this study, we assessed the temporal changes of the source contributions to riverine POM in two adjacent rivers of the same watershed during two summer storm events, which included the early and the late events, using end-member mixing analysis (EMMA) based on spectroscopic proxies. The EMMA showed relatively high contributions of terrestrial materials to the riverine POM for both rivers during the early summer storm event. However, this trend did not persist until the late summer storm event, which presented the decreased contributions of the terrestrial sources and less dynamic changes in the source distributions compared to those observed in the early summer rain event. These results demonstrate the combined impacts of the land use/surrounding area, the hydrology, and the intra-seasonal variations on the dominant riverine POM sources. This study provides an interesting insight into the importance of the intense hydrological events on the export of the terrestrial OM and further on the potential modification of the existing carbon mass balance along the continuum land-river-ocean.

Little is known about the environmental impacts of biochar (BC) amendment on the immobilization of heavy metals in compost-treated fields. In consequence, this study was designed to explore the effects of BC amendment on the copper (Cu) binding properties of compost-derived humic substances (HS). To this end, unamended and 4.7% (by wet weight) BC-amended compost were incubated in parallel with regular wetting for 6 months. The stability constants for Cu binding, calculated based on the fluorescence quenching technique, were higher for the compost-derived HS with versus without BC amendment. The result suggests that BC addition to compost may intensify the immobilization of heavy metals in a compost-treated field. Copper binding efficacy increased after the incubation with or without BC amendment. However, the enhanced Cu binding efficacy of the BC-amended HS was preserved even after the long-term incubation. Two-dimensional correlation spectroscopy revealed that the short wavelength fulvic-like fluorescence followed by humic-like fluorescence were preferentially associated with Cu binding. However, the range of wavelengths that tracked the binding of Cu were modified after BC amendment. This study evidenced beneficial and synergetic effects of BC amendment on the abatement of the potential environmental risk from heavy metal polluted field on a long-term basis.

Purpose: This study evaluated the clinical effects of heated humidified high flow nasal cannula (HHHFNC) treatment in pediatric pa tients with respiratory disease and respiratory insufficiency. Methods: We reviewed the medical records for clinical features and tests performed in patients admitted to Chungnam University Hospital pediatric ward and treated with HHHFNC between July 2014 and December 2018. We evaluated the effects of HHHFNC treatment in patients with bronchiolitis treated with oxygen using a nasal prong. Results: The 136 children were treated with HHHFNC during the study period, and their median age was 8 months. Among the 136 patients, 39 (28.7%) were diagnosed with bronchiolitis and pneumonia, 42 (30.9%) with pneumonia, 28 (20.6%) with bronchiolitis, and 3 (2.2%) with epilepsy. Thirty-five patients (25.7%) had underlying neurological disorders. Fifty-one (37.5%) received invasive ventilator treatment. After HHHFNC treatment, venous blood gas analysis showed a pH increase from 7.32 to 7.37 (P

Purpose The report of adverse events following immunization (AEFI) in Korea has continued since 1994, and the most frequently reported cases of AEFI of Korea Centers for Disease Control and Prevention (KCDC) is bacille Calmette-Guerin (BCG). Meanwhile, various inoculation methods and strains have been used in the past 6 years in Korea. Therefore, we investigated AEFI of BCG by strain types and inoculation methods using immunization safety surveillance of KCDC. Materials and methods We reviewed BCG AEFIs registered in the KCDC from January 2013 to June 2018. Results There were 336 AEFI cases during the period, and average time interval from vaccination to symptom onset was within 2 months. AEFI proportion was 6.4 cases per 100,000 doses for BCG percutaneous Tokyo strain, 41.6 cases per 100,000 doses of BCG intradermal Danish strain, and 25.9 cases per 100,000 doses of BCG intradermal Tokyo strain. Intradermal type was more reported AEFI than percutaneous type in the same strain. The most common adverse events were local reaction like BCG lymphadenitis and severe adverse reactions such as osteomyelitis or disseminated BCG disease were 0.1 to 0.2 cases per 100,000 doses which are correlated with the range of World Health Organization published AEFI rates. Conclusion The AEFI reporting rate does not equal the actual proportion of AEFI occurrence. Because AEFI monitoring is a passive surveillance system, various factors might influence the number of events reported. Nevertheless, it is important to analyze BCG AEFI by vaccine strains and inoculation method using surveillance data of KCDC.

In recent tissue engineering applications, the advance of biomaterials has focused on the devising of biomimetic materials that are directing new tissue formation and capable of causing specific cellular responses. These advances can be controlled by modifying the devising parameters of the materials. The biomimetic materials potentially mimic many roles of ECM in tissues. For the homogeneous distribution and biocompatibility of scaffolds by cell migration with biomimetic materials, cell migration is studied because it has a important role in physiological phenomenon and in pathologies; cancer metastasis, immune response or embryonic development. This review discusses the migration of cells with biomimetic materials for tissue engineering. It is also summarized that the recent advances of cell migration with biomimetic materials in 2-D and 3-D for tissue engineering.

Stem cell therapy that can restore function to damaged tissue, avoid host rejection and reduce inflammation throughout body without use of immunosuppressive drugs. The established methods were used to identify and to isolate specific stem cell markers by FACS or by immunomagnetic cell separation. The procedures for distinguishing population of stem cells took a time and needed many preparations. Here we suggest an electrotaxis analysis as a new method to evaluate the homogeneity of mesenchymal stem cells which can observe the stem cell population in culture condition and wide use to various types of stem cells. Human mesenchymal stem cell, adipose derived stem cell, tonsil derived stem cell and osteogenic differentiated cells migrated toward anode but the migration speed of differentiated cells was significantly decreased versus that of stem cells. In mixture of stem cells and differentiated cells condition, we identified that the ratio of stem cell versus differentiated cell was matched with the homogeneity evaluation data of stem cells based on electrotaxis analysis. As a result, our evaluation tool has the possibility of the wide use to stem cell homogeneity evaluation and might be used as the stem cell quality control during stem cell culture without any additional antibodies.

Background Bronchiectasis is a chronic pulmonary disease characterized by progressive and irreversible bronchial dilatation. The aim of the present study was to investigate the etiologies and clinical features of bronchiectasis in Korean children. Methods We performed a retrospective review of the medical records for children diagnosed with bronchiectasis between 2000 and 2017 at 28 secondary or tertiary hospitals in South Korea. Results A total of 387 cases were enrolled. The mean age at diagnosis was 9.2 ± 5.1 years and 53.5% of the patients were boys. The most common underlying cause of bronchiectasis was preexisting respiratory infection (55.3%), post-infectious bronchiolitis obliterans (14.3%), pulmonary tuberculosis (12.3%), and heart diseases (5.6%). Common initial presenting symptoms included chronic cough (68.0%), recurrent pneumonia (36.4%), fever (31.1%), and dyspnea (19.7%). The most predominantly involved lesions were left lower lobe (53.9%), right lower lobe (47.1%) and right middle lobe (40.2%). No significant difference was observed in the distribution of these involved lesions by etiology. The forced expiratory volume in 1 s (FEV1) levels were lowest in cases with interstitial lung disease-associated bronchiectasis, followed by those with recurrent aspiration and primary immunodeficiency. Conclusions Bronchiectasis should be strongly considered in children with chronic cough and recurrent pneumonia. Long-term follow-up studies on pediatric bronchiectasis are needed to further clarify the prognosis and reduce the disease burden in these patients.

Extensive skin loss caused by burns or diabetic ulcers may lead to major disability or even death. Therefore, cell-based therapies that enhance skin regeneration are clinically needed. Previous approaches have been applied the injections of cell suspensions and the implantation of biodegradable three-dimensional scaffolds seeded cells. However, these treatments have limits due to poor localization of the injected cells and insufficient delivery of oxygen and nutrients to cells. Recently, cell sheet-based tissue engineering has been developed to transplant cell sheets, which are cell-dense tissues without scaffolds. Because cell density is one of the important factors for improving the therapeutic effect of cell transplantation, transplanting layered cell sheet constructs can promote the recovery of tissue function and tissue regeneration compared with a single cell sheet. Thus, this study designed ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet delivery efficiency and application in wound healing. We have demonstrated the therapeutic effect of a multi-layered mesenchymal stem cell sheets onto a full-thickness wound defect in nude mice. Consequentially, three-layered cell sheets transplanted and stacked by ROS-induced method promoted angiogenesis and skin regeneration at the wound site. Thus, our strategy based on Hp-PK film, which allows for easy stacking and transplantation of cell sheets, could be applied to enhance tissue regeneration. STATEMENT OF SIGNIFICANCE: We herein report exogenous ROS-induced cell sheet stacking method with newly fabricated hematoporphyrin-incorporated polyketone film (Hp-PK film) to enhance cell sheet transplantation efficiency and application in wound healing. Although there are several ways to stack-up cell sheets, all of these methods have limitations in transplanting the cell sheet directly to the target site. The method is simple and takes a relatively short time compared to previously reported methods for stacking and transplanting cell sheets. Thus, our study will provide a scientific impact because the method of applying exogenous ROS generated from Hp-PK film on cell detachment can transplant the cell sheet through a process of putting a cell sheet-cultured film on the lesion, irradiating with light, and then removing only the film.

In contrast with the other natural disasters, drought is required of continuous and regular monitoring since its damage is very gradual. Satellite images can be utilized for comprehensively monitoring changes in water resources in dam reservoirs, watersheds, and rivers. It is very difficult to obtain continuous and regular images from optical sensors since they are susceptible to weather conditions, although they can provide fine images at high spatial resolution for land surface. This study used a synthetic aperture radar (SAR) regardless of weather or daylight conditions to monitor water surface change in a dam reservoir. The 18 dam basins of Korea peninsula were monitored and the changing patterns were analyzed. The results indicated that the change in water surface area was in good agreement with the depth of drought.

Air temperature is one of the most important variables in a wide range of application such as weather forecasts, climate, crop yield forecasting, agriculture and environment. In particular, continuous observations of daily maximum air temperature can identify the phenomenon and trend of the heat wave and prevent the heat related disaster. In this study, we have developed the daily maximum air temperature estimation algorithm using multiple linear regression equations. The input data is MODIS and ASOS data from 2013 to 2016 (June to September). The developed MODIS-based daily maximum air temperature estimation algorithm was applied to the MODIS images acquired from June to September in 2017. Then, we verified our result to the Seoul, Daejeon, and Ulsan areas in South Korea.

For a reason of limitations of optical data depending on weather conditions, the utilization of Synthetic Aperture Radar (SAR) data has been regarded as a complementary tool for understanding disaster field situations in recent years. Coincidentally, there were two large-scale earthquakes above magnitude 5.0 within the last a year in Korea. In this study, a Differential Interferometry SAR(DInSAR) technique is applied to analyze the ground deformation and its influence range by Pohang earthquake in Korea. Then the direction of the deformation was estimated in 3-dimension. Results show that the maximum of 5 cm uplift is observed in area covering 10km radius from the epicenter, and the principal direction appeared in north-northeast. More elaborated and continuous monitoring based on SAR data will need to make proper measures for expected future earthquakes.

Biochar-leached dissolved organic matter may have a substantial impact on the water quality of receiving water surrounded by biochar-amended fields. In this study, we tracked variations in the spectroscopic characteristics and the disinfection by-products formation potentials of dissolved organic matter (DOM) leached during sequential extraction for three different biochars (BCs), which simulates DOM from BC-amended fields during intermittent rain events. The optical properties of DOM were more dependent on the BC types with different origins (sludge, corn, and rice) rather than on the extraction time. A large amount of DOM was released during the initial period of the extraction (1 day), which was equivalent to 52–60% of the total cumulative organic carbon during 17 days of extraction. The relative contribution of the initial extraction to the total cumulative amounts was greater for the formation potential of trihalomethanes (THMs) per BC (71–82%) compared to those of haloacetic acids (HAAs) or dissolved organic carbon (DOC), suggesting that the leaching behaviors of disinfection byproducts (DBP) precursors from BCs may be different from those of DOC (i.e., bulk DOM). Among the three BCs, corn BC-derived DOM exhibited the highest formation potentials of THMs and HAAs per BC for both the initial and the total cumulative extraction. The specific (or DOC-normalized) THMs formation potential was positively correlated with the ratios of terrestrial humic-like to fulvic-like components, implying condensed aromatic structures could operate as a surrogate for THMs formation of BC-derived DOM. This study provided insight into dynamic leaching behaviors of DOM from BCs and the formation potentials for THMs and HAAs in BC-amended fields under intermittent rainfall.

In recent tissue engineering applications, the advance of biomaterials has focused on the devising of biomimetic materials that are directing new tissue formation and capable of causing specific cellular responses. These advances can be controlled by modifying the devising parameters of the materials. The biomimetic materials potentially mimic many roles of ECM in tissues. For the homogeneous distribution and biocompatibility of scaffolds by cell migration with biomimetic materials, cell migration is studied because it has a important role in physiological phenomenon and in pathologies; cancer metastasis, immune response or embryonic development. This review discusses the migration of cells with biomimetic materials for tissue engineering. It is also summarized that the recent advances of cell migration with biomimetic materials in 2-D and 3-D for tissue engineering.

Background Understanding the patterns of emergency department (ED) visits of patients with asthma is important for disease control and prevention of exacerbations. Objective This study aimed to investigate the characteristics of adult patients who visited EDs because of their asthma. Methods Patients with asthma, ages ≥19 years old, who visited 117 EDs throughout Korea between January 2007 and December 2012 were identified in the National Emergency Department Information System (NEDIS) data base using the International Classification of Disease, 10th revision, codes J45 (asthma) and J46 (status asthmaticus). Results A total of 97,835 adult patients with asthma visited 117 EDs throughout Korea during the study period. There was a slight female preponderance (male-to-female ratio, 1:1.09). The number of patients aged 70-79-years-old was 28,031 (28.7%), the highest among the patients with asthma. ED visits showed a seasonal distribution, with most occurring in winter and spring, followed by autumn. The seasonal distribution varied by age; most patients ages 19-49 years presented in autumn (September), whereas those patients ages ≥50 years presented to the ED most often in winter. Overall, 65.5% of patients were admitted to the hospital, including 12.6% admitted to an intensive care unit (ICU). Overall, 209 patients (0.2%) died. The rates of hospital admission to general wards and ICUs were highest in those patients ≥70 years old; this group also had the highest mortality rate. Conclusion In this nationwide study, which spanned 6 years, of adult patients with asthma, we observed an age-specific seasonal pattern of ED visits. Identifying the causes of age-related deterioration and seasonal visits to the ED will help prevent asthma symptoms and reduce medical costs.

Purpose Croup is a common pediatric respiratory illness with symptoms of varying severity. Moreover, epiglottitis is a rare disease that can rapidly progress to life-threatening airway obstruction. Although the clinical course and treatments differ between croup and epiglottitis, they are difficult to differentiate on presentation. We aimed to compare the clinical characteristics of croup and epiglottitis in Emergency Department patients. Methods The 2012 National Emergency Department Information System database of 146 Korean Emergency Departments was used to investigate patients aged ≤18 years presenting with croup or epiglottitis. Results We analyzed 19,374 croup patients and 236 epiglottitis patients. The male:female sex ratios were 1.9:1 and 2.3:1 and mean ages were 2.2±2.0 and 5.6±5.8 years, respectively. The peak incidence of croup was observed in July and that of epiglottitis was observed in May. The hospitalization rate was lower in croup than in epiglottitis patients, and the proportion of patients treated in the intensive care unit was lower among croup patients. The 3 most common chief complaints in both croup and epiglottitis patients were cough, fever, and dyspnea. Epiglottitis patients experienced dyspnea, sore throat, and vomiting more often than croup patients (P

The regulation of apoptosis, proliferation, and migration of fibroblasts is altered in keloids. The 90-kDa heat shock protein (heat shock protein 90) is known to play a key role in such regulation. Therefore, the authors investigated whether the inhibition of heat shock protein 90 in keloid fibroblasts could induce apoptosis and attenuate keloid fibroblast proliferation and migration.The authors evaluated heat shock protein 90 expression in keloid tissues with immunohistochemistry. The authors used cell viability [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays and annexin V/propidium iodide staining for apoptosis, a wound healing model and cell tracking system to assess cell migration, and Akt Western blotting analysis in keloid fibroblasts after inhibition of heat shock protein 90 with 17-allylaminodemethoxygeldanamycin (17-AAG).The expression of heat shock protein 90 in keloid tissues was significantly increased compared with normal tissues. The 17-AAG-treated keloid fibroblasts showed significantly decreased proliferation, promotion of apoptosis, and decreased expression of Akt. Furthermore, a dose-dependent decrease in cell migration was noted after 17-AAG treatment of keloid fibroblasts. The 17-AAG-treated keloid fibroblasts had less directionality to the wound center and migrated a shorter distance.The authors confirmed that the inhibition of heat shock protein 90 in keloid fibroblasts could promote apoptosis and attenuate proliferation and migration of keloid fibroblasts. Therefore, the authors think that the inhibition of heat shock protein 90 is a key factor in the regulation of biological processes in keloids. With further preclinical study, the authors will be able to apply these results clinically for keloid treatment.

The infiltration of the cells into the scaffolds is important phenomenon to give them good biocompatibility and even biodegradability. Fluid shear stress is one of the candidates for the infiltration of cells into scaffolds. Here we investigated the directional migration of human mesenchymal stem cells and infiltration into PLGA scaffold by fluid shear stress. The human mesenchymal stem cells showed directional migrations following the direction of the flow (8, 16 dyne/cm 2 ). In the scaffold models, the fluid shear stress (8 dyne/cm 2 ) enhanced the infiltration of cells but did not influence on the infiltration of Poly(lactic-co-glycolic acid) particles.

Background Medical devices inserted into the human body can be divided into single-use devices and reusable medical devices (RMDs) depending on the method of use. RMDs are applied to >1 patient, and users reprocess them prior to repeat use. Therefore, reprocessing of RMDs has become more difficult, and issues related to infection risk have become more prevalent. Methods Research was performed to compare differences in surface alterations between not-aged (NA) samples and accelerated-aging (AA) samples. NA and AA samples were exposed to potential contaminants and treated with the same cleaning conditions. Then the residual contaminants were analyzed, and adhesion characteristics were investigated. Results Significant differences between the 2 sample groups were observed in the pattern of physical surface alterations. Similar to the endoscope for clinical use, a deep crack was found in the surface of the AA sample. According to the binding affinity test, highly likely potential contaminants were found more frequently on AA samples. Conclusion The results suggest the necessity of limiting the duration of time that RMDs may be used, considering the potential risk of infection from repetitive use of RMDs, and also raised the possibility of applying this simulation model of AA. This methodology can be applied to various RMDs, including endoscopes.

Directional cell migration requires cell polarization. The reorganization of the Golgi apparatus is an important phenomenon in the polarization and migration of many types of cells. Direct current electric fields (dc (EF) induced directional cell migration in a wide variety of cells. Here nHDFs migrated toward cathode under 1 V/cm dc EF, however 1 μM of brefeldin A (BFA) inhibited the dc EF induced directional migration. BFA (1 μM) did not cause the complete Golgi dispersal for 2 h. When the Golgi polarization maintained their direction of polarity, the direction of cell migration also kept toward the same direction of the Golgi polarization even though the dc EF was reversed. In this study, the importance of the Golgi polarization in the directional migration of nHDf under dc EF was identified.

Many types of cells respond to applied direct current electric fields (dcEFs) by directional cell migration, a phenomenon called galvanotaxis or electrotaxis. In this study, electrotaxis was used to control cell migration. We designed a new electrotaxis incubator and chamber system to facilitate long-term (> 12 h) observation and to allow for alterations to the direction of the current. Poly(lactic-co-glycolic acid) (PLGA) was coated onto surfaces to mimic a commonly used tissue-engineering scaffolding environment. Neonatal human dermal fibroblasts (nHDFs) were grown on PLGA-coated surfaces and exposed to EFs at increasing currents in the range 0-1 V/cm. These cells migrated toward the cathode during 3 h of dcEF stimulation; however, the migration speed decreased with increasing electric fields. Cells exposed to dcEFs in the range 1-2 V/cm showed no changes to migration speed or x forward migration indices (xFMIs) and the cells continued to move toward the cathode. nHDFs showed directional migration towards the cathode in direct current (dc) EFs (1 V/cm) and they moved in the opposite direction when the polarity of the dcEF was reversed. Reorganization of the actin cytoskeleton and polarization of the Golgi apparatus were evaluated by immunostaining, which showed that the actin cytoskeleton elongated towards the cathode and the Golgi apparatus polarized in the direction of the dcEF. This study revealed that cell migration could potentially be controlled on PLGA scaffolds through electrotaxis. Copyright © 2015 John Wiley & Sons, Ltd.

To date, most of invasive cell sheet harvesting methods have used culture surface property variations, such as wettability , pH, electricity, and magnetism, to induce cell detachment . These methods that rely on surface property changes are effective when cell detachment prior to application is necessary, but of limited use when used for cell sheet transfer to target regions. The study reports a new reactive oxygen species (ROS)-induced strategy based on hematoporphyrin-incorporated polyketone film (Hp-PK film) to transfer cell sheets directly to target areas without an intermediate harvesting process. After green LED (510 nm) irradiation, production of exogenous ROS from the Hp-PK films induces cell sheet detachment and transfer. The study suggests that ROS-induced cell detachment property of the Hp-PK film is closely related to conformational changes of extracellular matrix (ECM) proteins. Also, this strategy with the Hp-PK film can be applied by regulating production rate of exogenous ROS in various types of cells, including fibroblasts, mesenchymal stem cells and keratinocytes . In conclusion, ROS-induced method using the Hp-PK film can be used for one-step cell sheet transplantation and has potential in biomedical applications .

The choice of hemostat is determined by the situation and the degree of hemorrhage. One common hemostat, the nonwoven dressing, is easy to handled and controls severe bleeding on wider wounds. In this study, chitosan-based nonwoven dressings with recombinant batroxobin (rBat) were used as efficacious hemostatic dressing agents. Hemostatic agents need to absorb blood quickly in the early stages of blood coagulation cascade to rapidly and effectively control of excessive hemorrhages. To date, most studies of hemostatic agents focused on a single material and hemostats composed of multiple materials have not been studied sufficiently. Thus, we made a chitosan dressing coated with rBat and investigated the microstructure, mechanical properties, hemostatic efficacy, and clotting properties of the coated dressing. Our results showed that the rBat had a synergetic effect on chitosan that improved blood coagulation. Furthermore, the dressing had excellent bleeding control in an Sprague-Dawley (SD) rat femoral artery hemorrhage model. In conclusion, hemostasis can be improved by combining a chitosan-based nonwoven dressing with other agents, and rBat-coated chitosan-based nonwoven dressings have enormous potential to improve blood coagulation.

Purpose Understanding changes in pathogen and pneumonia prevalence among pediatric pneumonia patients is important for the prevention of infectious diseases. Methods We retrospectively analyzed data of children younger than 18 years diagnosed with pneumonia at 117 Emergency Departments in Korea between 2007 and 2014. Results Over the study period, 329,380 pediatric cases of pneumonia were identified. The most frequent age group was 1-3 years old (48.6%) and the next was less than 12 months of age (17.4%). Based on International Classification of Diseases, 10th revision diagnostic codes, confirmed cases of viral pneumonia comprised 8.4% of all cases, pneumonia due to Mycoplasma pneumoniae comprised 3.8% and confirmed cases of bacterial pneumonia 1.3%. The prevalence of confirmed bacterial pneumonia decreased from 3.07% in 2007 and 4.01% in 2008 to 0.65% in 2014. The yearly rate of pneumococcal pneumonia also decreased from 0.47% in 2007 to 0.08% in 2014. A periodic prevalence of M. pneumoniae pneumonia (MP) was identified. Conclusion The increased number of patients with pneumonia, bacterial pneumonia, pleural effusion, and empyema in 2011 and 2013-2014 resulted from an MP epidemic. We provide evidence that the frequency of confirmed cases of bacterial pneumonia and pneumococcal pneumonia has declined from 2007 to 2014, which can simultaneously reflect the effectiveness of the pneumococcal conjugate vaccine.

Stem cell therapy that can restore function to damaged tissue, avoid host rejection and reduce inflammation throughout body without use of immunosuppressive drugs. The established methods were used to identify and to isolate specific stem cell markers by FACS or by immunomagnetic cell separation. The procedures for distinguishing population of stem cells took a time and needed many preparations. Here we suggest an electrotaxis analysis as a new method to evaluate the homogeneity of mesenchymal stem cells which can observe the stem cell population in culture condition and wide use to various types of stem cells. Human mesenchymal stem cell, adipose derived stem cell, tonsil derived stem cell and osteogenic differentiated cells migrated toward anode but the migration speed of differentiated cells was significantly decreased versus that of stem cells. In mixture of stem cells and differentiated cells condition, we identified that the ratio of stem cell versus differentiated cell was matched with the homogeneity evaluation data of stem cells based on electrotaxis analysis. As a result, our evaluation tool has the possibility of the wide use to stem cell homogeneity evaluation and might be used as the stem cell quality control during stem cell culture without any additional antibodies.

Small cell lung cancer (SCLC) cannot be efficiently controlled using existing chemotherapy and radiotherapy approaches, indicating the need for new therapeutic strategies. Although ABT-737, a B-cell lymphoma-2 (BCL-2) inhibitor, exerts anticancer effects against BCL-2-expressing SCLC, monotherapy with ABT-737 is associated with limited clinical activity because of the development of resistance and toxicity. Here, we examined whether combination therapy with ABT-737 and heat shock protein 90 (HSP90) inhibitor NVP-AUY922 exerted synergistic anticancer effects on SCLC. We found that the combination of ABT-737 and NVP-AUY922 synergistically induced the apoptosis of BCL-2-expressing SCLC cells. NVP-AUY922 downregulated the expression of AKT and ERK, which activate MCL-1 to induce resistance against ABT-737. The synergistic effect was also partly due to blocking NF-κB activation, which induces anti-apoptosis protein expressions. However, interestingly, targeting BCL-2 and MCL-1 or BCL2 and NF-κB did not induce the cytotoxicity. In conclusion, our study showed that combination of BCL2 inhibitor with HSP90 inhibitor increased activity in in vitro and in vivo study in only BCL-2 expressing SCLC compared to either single BCL2 inhibitor or HSP inhibitor. The enhanced activity might be led by blocking several apoptotic pathways simultaneously rather than a specific pathway.

Thrombus and infections are the most common causes for the failure of medical devices, leading to higher hospitalization costs and, in some cases, patient morbidity. It is, therefore, necessary to develop novel strategies to prevent thrombosis and infection caused by medical devices. Herein, we report a simple and a highly efficient strategy to impart antithrombotic and antimicrobial properties to substrates, by simultaneously immobilizing heparin and in situ-synthesized silver nanoparticles (Ag NPs) via a tyrosinase-catalyzed reaction. This consists of tyrosinase-oxidized phenolic groups of a heparin derivative (heparin-grafted tyramine, HT) to catechol groups, followed by immobilizing heparin and inducing the in situ Ag NP formation onto poly(urethane) (PU) substrates. The successful immobilization of both heparin and in situ Ag NPs on the substrates was confirmed by analyses of water contact angles, XPS, SEM, and AFM. The sustained silver release and the surface stability were observed for 30 days. Importantly, the antithrombotic potential of the immobilized surfaces was demonstrated by a reduction in fibrinogen absorption, platelet adhesion, and prolonged blood clotting time. Additionally, the modified PU substrates also exhibited remarkable antibacterial properties against both Gram-positive and Gram-negative bacteria. The results of this work suggest a useful, effective, and time-saving method to improve simultaneous antithrombotic and antibacterial performances of a variety of substrate materials for medical devices.

Scaffolds used in tissue engineering are usually porous for providing a passage and cell infiltration. In this study, we have investigated the effects of vapor pressure of solvents during electrospinning with dry ice on the pore sizes of the poly(lactic-co-glycolic acid) (PLGA) meshes and the cell behaviors in these meshes. The meshes fabricated with dry ice using 1,1,1,3,3,3,-hexafluoro-2-propanol (HFIP), which was the lowest vapor pressure of the experimental solvents, were not significantly different on the fiber connections as compared to those fabricated without dry ice. When electrospinning was processed using acetone with dry ice, numerous beads were observed in the meshes. The meshes which were fabricated using the tetrahydrofuran/dimethylformamide (THF/DMF) admixture with dry ice had loose connections between the fibers and showed large voids. In addition, the infiltration and the attachment of cells increased on these meshes due to large voids. Therefore, dry ice during electrospinning could cause an increase in pore size; however, these electrospinning processing was sensitive to the vapor pressure of the experimental solvent. Open image in new window

본 연구는 객관적인 국가차원의 국민건강영양조사 원시자료를 활용하여 만 14세에서 만 19세까지의 청소년을 추출하고 식품군별로 조사된 섭취빈도조사의 내용을 바탕으로 구강검진 조사의 항목으로 실시된 우식영구치수, 영구치우식유병자여부, 우식경험영구치수, 영구치우식경험여부등의 4가지 항목의 영향력 관계를 조사하였다. 우식영구치수, 영구치우식유병자 여부, 우식경험영구치 수, 영구치우식경험 여부등은 쌀과 배추 김치를 주식으로 하는 우리나라 식생활 문화에 가장 영향을 많이 받았고 쌀과 잡곡, 배추등의 채소와 과일류 등은 치아우식을 낮추는 영향을 주는 인자로 조사되었다. 쌀의 섭취 빈도가 많을수록 치아우식은 감소하는 것으로 나타났으며, 고기 생선 난류의 식품군에서는 멸치의 섭취 빈도가 많을 수록 치아우식은 감소하였고, 돼지고기와 소고기 등의 육류의 섭취 역시 치아우식의 발생을 감소시키는 것으로 나타났다. 특히 탄산음료와 패스트푸드 식품의 일종인 햄버거와 피자등의 섭취 빈도가 클수록 치아우식을 증가시키는 것으로 나타났다. 【This study applied an original survey of an objective National Health Nutriment Research. It picked the youth up from 14 years old to 19 years old and examined an influence relationship of four heads such as DT, DI, DMFT, DMFI which investigated in heads of dental inspections based on an intake frequency questionnaire by food group. It was proved that Korean dietary culture which eats rice and kimchi as staple food had an great effect on DT, DI, DMFT, DMFI And rice and cereals, fruits and vegetables like a cabbage turned out to be factors that can lower dental caries. The dental caries can be reduced by the more intake frequency of rice. And also, intake of fish like anchovy and meats like pork and beef can reduce development of dental caries too. Especially, the larger intake frequency of carbonated drinks and fast food such as hamburger and pizza can make a growth of dental caries.】

Dissolved organic matter (DOM) in river water dynamically changes with respect to its major sources during heavy rain events. However, there has been no established tool to estimate the relative contributions of different organic sources to river water DOM. In this study, the evolution in the contributions of ten different organic matter (OM) sources to storm water DOM was explored with a selected urban river, the Geumho River in South Korea, during storm events via an end-member mixing analysis (EMMA) based on fluorescence indices and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The OM source materials included treated effluent, road runoff, groundwater, topsoil, deep soil, leaves, reeds, riparian plants, attached algae, and suspended algae. The EMMA results provided quantitative estimates of the variations in the dominant OM sources with the progress of storms. Treated effluent was the prevailing source at the beginning period of the storm, while topsoil, leaves, riparian plants, and groundwater predominated during and after the peak period. The fluorescence indices-based evaluation was consistent with the statistical comparison of the molecular formulas derived from FT-ICR-MS conducted on the ten potential OM sources and the storm samples. The observed variations in the OM sources agreed with the typical characteristics of urban rivers in connection with anthropogenic inputs and the impact of surrounding impervious surfaces. This study demonstrates the application of intuitive and facile tools in estimating the relative impacts of OM sources in urban watersheds.

Inserting a graft into vessels with different diameters frequently causes severe damage to the host vessels. Poor flow patency is an unresolved issue in grafts, particularly those with diameters less than 6 mm, because of vessel occlusion caused by disturbed blood flow following fast clotting. Herein, successful patency in the deployment of an ≈2 mm diameter graft into a porcine vessel is reported. A new library of property-tunable shape-memory polymers that prevent vessel damage by expanding the graft diameter circumferentially upon implantation is presented. The polymers undergo seven consecutive cycles of strain energy-preserved shape programming. Moreover, the new graft tube, which features a diffuser shape, minimizes disturbed flow formation and prevents thrombosis because its surface is coated with nitric-oxide-releasing peptides. Improved patency in a porcine vessel for 18 d is demonstrated while occlusive vascular remodeling occurs. These insights will help advance vascular graft design.

Epigallocatechin-3-O-gallate (EGCG) is a major polyphenolic compound in green tea. It has been known that EGCG regulates the secretion of cytokines and the activation of skin cells during wound healing. In this study, various concentrations of EGCG were added to the electrospun membranes composed of poly (lactic-co-glycolic acid) (PLGA), and its healing effects on full-thickness wounds created in nude mice were investigated. The electrospun membranes containing 5 wt% EGCG (5EGCG/PLGA membrane) exhibited cytotoxicity in human dermal fibroblasts (HDFs) as HDF morphologies were transformed on them. In the animal study, cell infiltration of mice treated with electrospun membranes containing 1 wt% EGCG (1EGCG/PLGA membrane) significantly increased after 2 weeks. The immunoreactivity of Ki-67 (re-epithelialization at the wound site) and CD 31 (formation of blood vessels) also increased in the mice treated with 1EGCG/PLGA membranes in comparison with the mice treated with PLGA membranes. These results suggest that 1EGCG/PLGA can enhance wound healing in full thickness by accelerating cell infiltration, re-epithelialization, and angiogenesis.

Changes in the apparent characteristics of dissolved organic matter (DOM) upon photodegradation and their influences on disinfection by-products formation potentials (DBPFP) were examined using biodegraded DOM from six different sources (leaf litter, algae, compost, paddy water, treated sewage, and headwater). After seven day UV irradiation, no substantial changes occurred in the dissolved organic carbon (DOC) concentrations, but significant decreases were observed for the specific UV absorbance. In general, fulvic-like and humic-like fluorophores appear to be more affected by photodegradation than protein-like fluorophores (or DOM components) and/or than the DOM structures associated with a shorter excitation wavelength. Size exclusion chromatograms revealed that UV absorbing molecules of intermediate size ranging from 1 to 5 kDa were most vulnerable to the UV irradiation. Except for leaf litter-derived DOM, UV irradiation did not lead to substantial changes in specific DBPFP (i.e. disinfection by-product (DBP)/dissolved organic carbon) comparable to those of the DOM characteristics, suggesting that many of the DBP precursors were not easily removed by photodegradation or some photochemically produced compounds could operate as DBP precursors. All the DOM samples exhibited greater formation potential for haloacetic acids per organic carbon than trihalomethanes irrespective of the sources. In general, correlations between DOM properties and specific DBPFP became stronger after photodegradation. The intermediate sized UV-absorbing moieties appear to be actively involved in forming DBPs for photodegraded DOM. An integrated region of protein-like fluorescence intensities may be suggested as an estimation index for specific DBPFP independent of the DOM sources.

OBJECTIVES The purpose of this study was to evaluate the effectiveness of real-time fusion imaging (sonography combined with computed tomography or magnetic resonance imaging) for percutaneous sonographically guided biopsy of focal hepatic lesions with poor sonographic conspicuity. METHODS This study was conducted as a retrospective analysis of a prospective database and was approved by the Institutional Review Board. Patients who had target lesions with poor conspicuity on B-mode sonography for percutaneous biopsy were enrolled in the study. Lesion conspicuity was assessed by conventional B-mode sonography first and then by fusion imaging later in the same session. We compared lesion conspicuity and detection rates between B-mode sonography and fusion imaging and evaluated how many cases of initially invisible lesions on B-mode sonography became visible on fusion imaging. The technical success rate was evaluated on the basis of the final diagnoses, which were established by pathologic examination of the biopsy specimens as well as follow-up clinical and radiologic examinations. RESULTS A total of 22 patients were enrolled in the study. On fusion imaging, lesion conspicuity was increased in 63.6% of focal hepatic lesions (14 of 22). Moreover, 66.7% of lesions (6 of 9) that were invisible on B-mode sonography became visible on fusion imaging. The true-positive detection rate was significantly different between B-mode sonography and fusion imaging (9 of 22 versus 19 of 22; P = .0044). Percutaneous biopsy was performed for all lesions, including 3 target lesions that were invisible even on fusion imaging. The technical success rate was 95.5% (21 of 22). CONCLUSIONS Fusion imaging is effective for percutaneous biopsy of focal hepatic lesions with poor sonographic conspicuity.

Purpose To investigate the characteristic sonographic (US) findings of pure ductal carcinoma in situ (DCIS) in a large series. Methods We retrospectively reviewed the US findings of 126 cases of pure DCIS in 123 consecutive patients who underwent surgery for breast cancer in our hospital. We analyzed the US findings of the lesions according to mass or nonmass abnormality, shape, margin, orientation, echogenicity, echotexture, boundary echo, posterior acoustic features, presence of associated ductal dilatation, presence of intralesional cystic focus, and presence of microcalcifications on US. We compared the US characteristics of pure DCIS with and without mammographic microcalcifications. Results Seventy-eight cases of pure DCIS had microcalcifications and 48 had no microcalcifications on mammography (MG). Overall, 109 cases (86.5%) of pure DCIS were demonstrated on US. DCIS with microcalcifications on MG showed positive US findings in 79.5% of cases. The most common US finding was heterogeneous hyper- or isoechoic parenchyma with intralesional microcalcifications and without posterior acoustic features. DCIS without microcalcifications on MG showed positive US findings in 97.9% of cases. The most common US findings were masses with round or oval shape, microlobulated margin, parallel orientation, heterogeneous mild hypoechogenicity, and without boundary echo or posterior acoustic features. Ductal dilatations and intralesional cystic foci were present in 17.5% (22/126) and 23.8% (30/126) of pure DCIS, respectively. Conclusions Overall, US could demonstrate 85.7% of pure DCIS cases, including 16 (12.7%) cases of clinically and mammographically occult pure DCIS. DCIS with and without microcalcifications on MG showed different US characteristics. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound, 41:465–471, 2013

The aim of this study is to examine the effects of the story sharing activity on-conflicting situations by the use of children’s story on the theory of mind and peer competences of preschoolers so that appropriate teaching materials can be allocated for the actual preschool education site. The subjects of this study were 46 preschoolers under the age 4 at the attached kindergarten of P University in Pohang City, Gyeongbuk and in which 23 children among them were assigned to a test group and the other 23 to a control group. The collected data was analyzed by SPSS ver. 15.0 program and Cronbach’s a coefficient was yielded to verify the reliability for each scale. The multivariate analysis of covariance (MANCOVA) was conducted. The analysis results are as follows. First, the story sharing activity on conflict situations by using children’s story had a significant effect on the preschoolers’ general appearance and actual task as sub-factors of the theory of mind, whereas no significant effects were found regarding the content change task and position change task. Second, the story sharing activity on conflict situations by using children’s story had significant effect on the preschoolers’ overall sensitivity, insecurity and pro-sociability as sub-factors of the peer competences, whereas no significant effects were found regarding the aggression, exclusivity and anti-sociability.

Background Gadoxetic acid and diffusion-weighted imaging (DWI) is increasingly used for the diagnosis of hepatocellular carcinoma (HCC). It is relevant to refine the diagnostic parameters for HCC, using state-of-the-art imaging techniques. Purpose To validate usefulness of magnetic resonance imaging (MRI) criteria with gadoxetic acid-enhanced MRI and DWI for diagnosis of small HCC by differentiation from dysplastic nodule (DN) or regenerative nodule (RN) in cirrhotic patients with strongly suspected small HCC. Material and Methods One hundred and eight patients with 102 HCCs and 29 benign nodules including 21 DNs and two large RNs (≤ 2.0 cm), and 40 patients with no HCC underwent gadoxetic acid-enhanced MRI and DWI. All patients also underwent MDCT. Index MR criteria for HCC were: (i) arterial hyperenhancement and hypointensity on hepatobiliary phase (HBP) with hyperintensity on DWI; (ii) hypovascular nodule with hyperintensity on DWI; (iii) arterial hyperenhancement and hypointensity on HBP without hyperintensity on DWI; (iv) arterial hyperenhancement and either iso- or hyperintensity on HBP, with hyperintensity on DWI; and (v) hyperintensity only on DWI. According to these criteria, MRI findings for HCCs and benign nodules were independently classified by two reviewers. Results On multidetector-row computed tomography, 64 HCCs (62.7%) showed typical features for HCC while 13 (12.8%) were not identified. On MRI, 84 HCCs (82.4%) showed arterial hyperenhancement and hypointensity on HBP, and hyperintensity on DWI. Eight HCCs were regarded as hypovascular HCCs with hyperintensity DWI (category 2). One HCC (0.6 cm in diameter) was demonstrated only by DWI. For each observer, 101 (99.0%) and 100 HCCs (98.0%) were discernible when applying all MRI criteria for HCC, respectively. Three DNs also fit the HCC criteria, thus the specificity was 90.9% for both observers. Conclusion With the HCC criteria based on combined gadoxetic acid-enhanced MRI and DWI, it is possible to reliably diagnose small HCC including hypovascular HCCs.

Presently, commercially available porous bone substitutes are manufactured by the sacrificial template method, direct foaming method, and polymer replication method (PRM). However, current manufacturing methods provide only the simplest form of the bone scaffold and cannot easily control pore size. Recent developments in medical imaging technology, computer-aided design, and solid freeform fabrication (SFF), have made it possible to accurately produce porous synthetic bone scaffolds to fit the defected bone shape. Porous scaffolds were fabricated by SFF and PRM for a comparison of physical and mechanical properties of scaffold. The suggested three-dimensional model has interconnected cubic pores of 500 μm and its calculated porosity is 25%. Whereas hydroxyapatite scaffolds fabricated by SFF had connective macropores, those by PRM formed a closed pore external surface with internally interconnected pores. SFF was supposed to be a proper method for fabricating an interconnected macroporous network. Biocompatibility was confirmed by testing the cytotoxicity, hemolysis, irritation, sensitization, and implantation. In summary, the aim was to verify the safety and efficacy of the scaffolds by biomechanical and biological tests with the hope that this research could promote the feasibility of using the scaffolds as a bone substitute.

Summary Changes in disinfection byproduct (DBP) precursors during storm events have not been intensively studied to date despite their dramatic impact on downstream drinking water supplies. For this study, variations in dissolved organic matter (DOM) spectroscopic properties and DBP formation potentials (DBPFPs), and the correlations among these various parameters, were investigated in river water samples collected under two contrasting storm event conditions (a strong summer storm versus a weak fall event). Fluorescence excitation–emission matrices (EEMs) combined with parallel factor analysis revealed that a combination of two humic-like components (C1 and C2) dominated the EEM data of the storm samples. Measured DOM characteristics and DBPFPs varied over a wider range during the more intense summer storm, exhibiting higher values of specific ultraviolet absorbance and C1/C2 ratio at high flow conditions. Variations in the fluorescence index were less pronounced during the two storm events. The spectroscopic changes were well explained by the input of terrestrial DOM sources from the surrounding catchments during the storms. Different trends of the formation potentials for trihalomethanes and haloacetic acids on the recession limb of the hydrographs suggest that the structures responsible for DBP precursors during storm events may not be the same for the two classes of DBPs. The ultraviolet light-absorbing moieties in DOM appear to play major roles in generating DBPs, as evidenced by their strong positive correlations with DBPFPs. Higher correlations with DBPFP for C1 versus C2 suggest that humic-like substances associated with more aromatic and condensed structures have a greater proclivity to generate DBP upon chlorination.