Resistance profiling and molecular characterization of Staphylococcus aureus isolated from goats in Korea.

Staphylococcus aureus is among the most common zoonotic pathogens that cause foodborne illnesses worldwide. The main objectives of the current study were therefore to determine the antimicrobial susceptibility profiles of S. aureus isolated from goats in Korea and to investigate the molecular characteristics of identified methicillin-resistant S. aureus (MRSA). In the study, 481 S. aureus isolates (431 from the nasal cavity and 50 from carcass) were recovered from 1146 carcasses and nasal swabs between July 2018 and January 2019. Approximately 82% and 72.6% of nasal and carcass isolates, respectively, were resistant to at least one antimicrobial agent, with the highest rate of resistance to penicillin, followed by resistance to chloramphenicol and tetracycline. Relatively small proportions of the isolates were resistant to cefoxitin, clindamycin, and erythromycin. However, all S. aureus isolates were sensitive to linezolid, rifampin, and vancomycin. Six MRSA isolates were obtained, three each from the nasal cavity and carcass. MRSA isolates were of two sequence types (ST) (ST72 and ST398), three spa types (t664, t324, and t571), and two SCCmec types (IV and V). The ST72 MRSA isolates had identical PFGE profiles. In addition, ST72 MRSA-SCCmec IV isolates carried at least six staphylococcal leukotoxin- and enterotoxin-encoding genes (lukED, seg, sei, sem, sen, seo, and seq). The remaining ST398 isolate carried only the lukED gene and was additionally resistant to eight non-ß-lactam antibiotics. To the best of our knowledge, this is the first report of MRSA from goats in Korea. There is a possibility of transmission of MRSA from goat to human or contamination of food products. Therefore, regular microbiological investigation in goats, farms, and slaughterhouses is critical to determine the existence of virulent and multi-drug resistant (MDR) S. aureus and to implement preventive strategies.

Isolation of a chemical inhibitor against K-Ras-induced p53 suppression through natural compound screening.

The strong tumor suppressor p53 shows loss of function in large portion of human cancer. In addition to genetic mutation, biological function of p53 is suppressed by signaling distortion or elevated expression of p53 inhibitors (such as overexpression of MDM2 or deletion of p14/ARF). In this study, we demonstrate that K-Ras, a frequently altered oncogene in human cancers including pancreatic cancer (about 80%), colon cancer (45%) and lung cancer (45%), suppresses p53. Based on this fact, we perform Western blot analysis-based chemical screening to isolate a K-Ras-specific activator of p53. From 117 kinds of chemicals (34 kinds of natural compounds that are obtained from herbal plants, 53 kinds of flavonoid, and 31 kinds of phenolic compounds), we find that quercetin works as an activator of p53 in K-Ras mutated cells but not in wild-type cells. Treatment with quercetin can induce p53 target genes such as PUMA and p21. These results suggest that although quercetin has limitations for use as a therapeutic drug due to its broad effects, specific function of it on K-Ras-p53 may be useful for K-Ras-induced cancer prevention and therapy through further development.

Spectrofluorimetric determination of vitamin B(1) using horseradish peroxidase as catalyst in the presence of hydrogen peroxide.

In this work a new spectrofluorimetric method for the determination of vitamin B(1), based on the catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2), has been developed. Non-fluorescent vitamin B(1) was easily converted through catalytic oxidation in alkaline medium into a fluorescent compound, even without exposure to light. The linear range for vitamin B(1) observed was 0.026-16.83 microg/mL (RSD = 1.75%). The correlation coefficient for the calibration curve and limit of detection were found to be 0.9964 and 0.015 microg/mL, respectively. The developed method is practical, simple, sensitive and relatively free from interference by coexisting substances and has been successfully applied for the determination of vitamin B(1) in pharmaceutical preparations.

Development of a sensitive flow-injection-chemiluminescence detection method for the determination of levodopa.

A simple chemiluminometric method using flow injection has been developed for the determination of levodopa, based on its sensitizing effect on the weak chemiluminescence (CL) reaction between Na(2)SO(3) and acidic KMnO4. Under optimum experimental conditions, the CL intensity was linearly related to the concentration of levodopa from 3.4 x 10(-8) to 2.4 x 10(-5) mol/L and the detection limit was 1.1 x 10(-8) mol/L (s:n = 3). The relative standard deviation (RSD) of the proposed method calculated from 20 replicate injection of 3 x 10(-7) mol/L levodopa was 3.3%. The correlation coefficient was 0.997. The method was successfully applied to the determination of levodopa in commercial pharmaceutical formulations and spiked urine samples.

Optical flow-through sensor for the determination of norfloxacin based on emission of KMnO(4)-Na (2)SO (3)-Tb (3+) system.

A simple and selective method to determine norfloxacin using an optical flow-through sensor has been developed. The present sensor was prepared by packing anionic ion exchange resin in a glass tube, followed by introducing KMnO(4) solution to the glass tube for immobilization on resin. The optical sensor is based on the emission intensity from the Tb(III) solution sensitized by norfloxacin. The excitation of norfloxacin occurred by the chemiluminescence from the reaction of KMnO(4) and Na(2)SO(4) solutions. The effects of pH, concentration of Tb(III) ion, KMnO(4) and Na(2)SO(4) solutions and flow rate of the norfloxacin solution on the chemiluminescence intensity were studied to find the optimum experimental conditions. The emission intensity increased linearly with increasing norfloxacin concentration from 1.0 x 10(-3) to 1.0 x 10(-8) M and the detection limit (3sigma) was 8.7 x 10(-9). The applicability of the present method was demonstrated by determination of norfloxacin in various pharmaceutical preparations and serum sample.

A putative early response of antifungal Bacillus lentimorbus WJ5 against the plant pathogenic fungus, Colletotrichum gloeosporioides, analyzed by a DNA microarray.

The global RNA transcription profiles of Bacillus lentimorbus WJ5 under an in vitro co-culture with Colletotrichum gloeosporioides were analyzed in order to study the antagonistic bacteria-fungi interactions. Using a filter membrane system, B. lentimorbus WJ5 was exposed to the spores of C. gloeosporioides at the late exponential stage. The transcription profiles of the B. lentimorbus WJ5, both with and without a challenge from C. gloeosporioides, were analyzed using custom DNA chips containing 2,000 genome fragments. A total of 337 genes were expressed, with 87 and 47 up- and down-regulated, respectively. Of these, 12 genes, which were involved in central carbon metabolisms, and 7 from minor catabolism were relatively highly up-regulated (> 10 fold) and down-regulated (< 0.2 fold), respectively. Nine genes, which were thought to be related to the antifungal activity, were also up-regulated, but their levels were not so high (2.0 - 9.7 folds). From the results, during the early stage of the co-culture of B. lentimorbus WJ5 and C. gloeosporioides, nutrient competition seemed to occur; therefore, the genes from central carbon metabolisms could be up-regulated, while those from minor catabolism could be down-regulated.

Determination of metallic impurities in a silicon wafer by local etching and electrothermal atomic absorption spectrometry.

An etching technique for the determination of the metallic impurities distribution in silicon wafers has been developed. An area of 10 mmphi and 10 microm depth was etched by 100 microL of an etching solution with a HF and HNO3 mixture. The acid matrix was evaporated on the wafer surface by IR lamp illumination and vacuum exhaust. Metallic impurities remaining on the wafer surface were redissolved into the collection solution, which was measured by electrothermal atomic absorption spectrometry (ET-AAS). The recovery invested by local etching/ET-AAS was within 95 - 112% for Fe, Cu and Ni. The detection limit (3sigma) for Fe, Cu and Ni in silicon was 1 x 10(13) atoms/cm3. To confirm the applicability, local etching was applied to evaluate the effects of metallic impurities in a gettering study and the electronic properties of semiconductor devices. It was found that local etching is a useful sample preparation technique for the analysis of metallic impurities in a specific area on a silicon wafer.