20 research outputs found
Human-centered software development methodology in mobile computing environment: agent-supported agile approach
Ultrasound-Guided Fine-Needle Aspiration Biopsy of Thyroid Nodules Smaller Than 5 mm in the Maximum Diameter: Assessment of Efficacy and Pathological Findings
Differentiation between Benign and Malignant Solid Thyroid Nodules Using an US Classification System
Mild acid-based surfactant-free solutions of single-walled carbon nanotubes: Highly viscous, less toxic, and humidity-insensitive solutions
Owing to their exceptional physical properties, single-walled carbon nanotubes (SWNTs) are widely applicable if translated into macroscopically assembled SWNT materials. The assembly method involves SWNT solutions prepared using surfactants or superacids. As both variations of the method are difficult to industrialize, a novel SWNT solution is prepared herein using mild polyphosphoric acid (PPA) without surfactant. Although the dissolution of SWNTs in PPA is thermodynamically unfavorable because of lower acidity compared to superacids, high viscosity kinetically contributes to phase stabilization when SWNTs are de-bundled upon high shearing. Interestingly, the SWNT/PPA solution is humidity-insensitive, which is beneficial for handling. In the 0.01???2.0 wt% range, the critical concentration and saturation point, at which phase transitions of isotropic-liquid crystalline (LC) and LC-gel states occur, are observed at 0.1 and 1.0 wt%, respectively. According to the steady shear rheology, the optimal concentrations for fiber spinning are 0.3???0.7 wt%. Polarized Raman and WAXD analyses show that the wet-spun SWNT fibers from the 0.5 wt% solution exhibit the highest fiber orientation, correlating with the lowest extrusion shear stress of the solution. The KevlarTM p-aramid dissolved in PPA and blended with SWNTs shows a negligible effect on the solution rheology but higher fiber modulus at high fractions
N2O dynamics in the western Arctic Ocean during the summer of 2017
Abstract The western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean: + 2.3 ± 2.7 μmol N2O m−2 day−1), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N2O m−2 day−1). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O “hot spot”, and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes
Fenobam promoted the neuroprotective effect of PEP-1-FK506BP following oxidative stress by increasing its transduction efficiency
In vitro antibacterial and synergistic effect of phlorotannins isolated from edible brown seaweed Eisenia bicyclis against acne-related bacteria
To develop effective and safe acne vulgaris therapies with a continuing demand for new solutions, we investigated unique efficacy of an antibacterial agent from marine brown alga Eisenia bicyclis in treating acne vulgaris. The methanolic extract of E. bicyclis exhibited potential antibacterial activity against acne-related bacteria. The ethyl acetate fraction showed the strongest antibacterial activity against the bacteria among solvent fractions. Six compounds (1-6), previously isolated from the ethyl acetate fraction of E. bicyclis, were evaluated for antibacterial activity against acne-related bacteria. Among them, compound 2 (fucofuroeckol-A [FF]) exhibited the highest antibacterial activity against acne-related bacteria with a minimum inhibitory concentration (MIC) ranging from 32 to 128 μg mL -1 . Furthermore, FF clearly reversed the high-level erythromycin and lincomycin resistance of Propionibacterium acnes. The MIC values of erythromycin against P. acnes were dramatically reduced from 2,048 to 1.0 μg mL -1 in combination with MIC of FF (64 μg mL -1 ). The fractional inhibitory concentration indices of erythromycin and lincomycin were measured from 0.500 to 0.751 in combination with 32 or 64 μg mL -1 of FF against all tested P. acnes strains, suggesting that FF-erythromycin and FF-lincomycin combinations exert a weak synergistic effect against P. acnes. The results of this study suggest that the compounds derived from E. bicyclis can be a potential source of natural antibacterial agents and a pharmaceutical component against acnerelated bacteria. Key Words: acne-related bacteria; antimicrobial activity; Eisenia bicyclis; phlorotannins; synergistic effect INTRODUCTION Acne vulgaris is a common skin disease affecting children and adolescents. The pathogenesis of acne is multifactorial and complex. There are four important factors that cause acne in humans, such as an increase in sebum secretion, keratinization of the follicle, bacteria, and inflammation 48 MATERIALS AND METHODS Raw materials and extraction In late September 2010, E. bicyclis was purchased from Ulleung Trading Co. (Ulleung-gun, Korea). A voucher specimen has been deposited in the author's laboratory. Dried E. bicyclis was finely ground and powdered with a food mixer (HMF-1000A; Hanil Electronics, Seoul, Korea). The dried powder was vacuum-packed and kept at -20°C until use. The dried E. bicyclis powder (1.0 kg) was extracted with methanol (MeOH; 10 L × 3) at 70°C for 3 h (3 times) and the solvent was evaporated in vacuo with a rotary evaporator (N-1001S-W; Eyela, Tokyo, Japan). The crude MeOH extract of E. bicyclis was suspended in 10% MeOH (1.0 L) and then partitioned in turn with nhexane (Hexane), dichloromethane (DCM), ethyl acetate (EtOAc), and n-butanol (BuOH) in sequence. The concentration of each extract was adjusted to 200 mg mL -1 by dissolving in dimethyl sulfoxide under sterile conditions and stored at -70°C until used. Microorganism and culture The following bacterial strains obtained from the Korean Collection for Type Cultures (KCTC; Daejeon, Korea) were used as indicator microorganisms in the study: P. acnes (KCTC 3314), S. aureus (KCTC 1927), S. epidermidis (KCTC 1370), P. aeruginosa (KCTC 1637), which were used for evaluation of anti-acne-related bacterial effect. Two strains of P. acnes clinical isolates were provided by the Gyeongsang National University Hospital (Jinju, Korea), a member of the National Biobank of Korea. P. acnes strains were anaerobically cultivated in brain heart infusion broth (BHI; Difco Inc., Detroit, MI, USA) supplemented with 1.0% glucose, and incubated at 37°C for 24 h in a CO 2 incubator (NAPCO 5400; General Laboratory Supply, Pasadena, TX, USA), in a 10% CO 2 humidified atmosphere. As for determining the growth curves of bacterial cells under optimal growth conditions, cultures of P. acnes were diluted and plated on BHI-agar. The plates were incubated at 37°C for 24 h in a 10% CO 2 incubator and the number of colony-forming units (CFU) was determined. S. aureus, S. epidermidis, and P. aeruginosa were grown aerobically at 37°C in tryptic soy broth (TSB; Difco Inc.). The disk diffusion assay was prepared in Mueller-Hinton agar (MHA; Difco Inc.) and the broth dilution method was carried out in Mueller-Hinton broth (MHB; Difco Inc.) according to the Clinical and Laboratory Standards Institute (CLSI) guidelines (formerly been recognized as pus-forming organisms that trigger inflammation in acne. Especially, P. acnes, one of the commonly isolated skin organisms, induces an inflammation of the sebaceous glands in human face, neck, chest or back To overcome the problem of side effects, medicinal plants and marine organisms have been investigated for the treatment of acne. Therefore, we investigated the possibility that they may be effective acne treatments based on the previously known anti-methicillin-resistant S. aureus effects of phlorotannin isolated from brown alga Eisenia bicyclis. E. bicyclis is a common perennial phaeophyceae (brown alga) and generally inhabits the region of Ulleung Island in the East sea of Korea. This seaweed has been added to appetizers, casseroles, muffins, pilafs, and soups Lee et al. Antibacterial Activities of Eisenia bicyclis 49 http://e-algae.kr Synergistic effects of fucofuroeckol-A (FF) with tetracycline, erythromycin, and lincomycin against Propionibacterium acnes The interaction between FF and antibiotics including tetracycline, erythromycin, and lincomycin (Sigma Chemical Co., St. Louis, MO, USA) against P. acnes was tested by the checkerboard method Statistical analysis In all cases analyses were performed in triplicate and data were averaged over the three measurements. The standard deviation (SD) was also calculated. Significance of differences between average MICs for each individual microorganism were determined by Student's t test at the 95% significance level using SPSS version 12.0 (SPSS Inc., Chicago, IL, USA). RESULTS Anti-acne related bacteria activity of Eisenia bicyclis extracts The antibacterial activity of methanol extract and its solvent fractions are presented in National Committee for Clinical Laboratory Standards [NCCLS]). Disk diffusion assay The antibacterial efficacy was evaluated by disk diffusion assay described by the CLSI (2009). In brief, bacterial strains were cultured in TSB at 37°C until cells reached at an OD 600 nm of 0.5. One hundred microliter of bacterial culture containing approximately 10 4 -10 5 CFU mL -1 was spread on MHA agar plates. A paper disc (6 mm in diameter) containing 1 mg and 5 mg of each extract was placed in the above MHA plate. After incubating for 24 h at 37°C, the diameter of the inhibition zone was measured on bacterial culture plates. The experiment was carried out three times and the mean values were presented. Determination of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) The concentration of MeOH extract and its solvent fractions of E. bicyclis was 200 mg mL -1 . Each extracts was diluted with MHB to obtain a stock solution of 2,048 μg mL -1 . To determine the MIC values of the MeOH extract and its solvent fractions of E. bicyclis, a stock solution of extracts was prepared in microbial culture medium for each microbial species. The MICs are the lowest concentration of MeOH extracts and its solvent fraction of E. bicyclis to inhibit the visible growth of microorganisms after overnight incubation using MHB, which was modified from the methods described for antimicrobial susceptibility testing by the CLSI (2006). MIC was defined as the lowest concentration of crude extract that inhibited the visual growth after incubating the aerobic bacteria for 18 h and the anaerobic bacteria for 48 h. MICs of the solvent-soluble extracts were determined by the two-fold serial dilution method in 96-well flat-bottomed microtitration plates at final concentration of 7 × 10 5 CFU mL -1 . The microtitration plates were read visually and the MIC of the extracts that exhibited no turbidity was recorded as the MIC. For MBC testing, an aliquot of inoculum was taken with a MIC test well that did not show turbidity, and was poured onto nutrient agar (Difco Inc.) plates for each bacterial species. The agar plates were incubated for 2 days for aerobic bacteria and 5 days for anaerobic bacteria. The MBC value was read as the lowest concentration of the solvent-soluble extracts at which 99.99% or more of the initial inoculum was killed. The MIC and MBC experiments were repeated in triplicate. 50 food-pathogen bacteria. The MBC values of EtOAc-soluble fraction against P. acnes strains were determined from 128 to 512 μg mL -1 MIC value of isolated phlorotannins from Eisenia bicyclis According to above results, the EtOAc-soluble fraction of E. bicyclis showed the strongest antibacterial activity against acne-related bacteria. In order to identify an anti-acne substance from the EtOAc-soluble fractions of E. bicyclis, we screened the antibacterial activity of previously isolated phlorotannins against acne-related bacteria. It is reported that marine-derived polyphenols (phlorotannins) are believed as the active components of E. bicycli