Changes in Oral Health Behavior According to Dental Calculus Removal Health Insurance in Korea.

BACKGROUND: Periodontal disease is a chronic disease that is increasing year by year. Korea also recognizes the seriousness of periodontal disease and has been applying preventive scaling in the National Health Insurance since 2013 to prevent it. Studies confirming the effectiveness of such insurance coverage are very scarce. Therefore, this study intended to confirm the effect of such policy by comparing and analyzing the oral health characteristics and oral health behavior of the South Koreans before and after the scaling insurance. METHODS: For all the analyses, complex sampling analysis with the stratification variable, clustering variable, and weight was applied. For a total of 40,945 people, the demographic characteristics, oral health characteristics, dental clinic use, brushing, and use of oral care supplies were compared through chi-square tests. RESULTS: Scaling insurance showed a positive effect (p < 0.05) on the unemployed and elderly people, who had lost their previous economic status; on smoking and willingness to quit smoking as well as on consultation on drinking problems; on dental-clinic use and oral examination in terms of utilization of dental clinics; and on brushing after lunch, before breakfast, and before sleeping. CONCLUSIONS: The study results showed that the scaling rate was universalized, and there was a positive effect on willingness to quit smoking and undergo oral examination. An active reimbursement policy for oral health education is needed, however, if a substantial change in oral health behavior is to be achieved.

Analysis of Quantitative Light-Induced Fluorescence Images for the Assessment of Bacterial Activity and Distribution of Tongue Coating.

This study aimed to verify and to validate the correlation between, and validate the assessment of, bacterial activity and the distribution of tongue coating, by analyzing quantitative light-induced fluorescence (QLF) images for the diagnosis of oral malodor. Oral malodor was measured using the Twin Breasor II, and bacterial activity and the distribution of tongue coating were investigated using QLF images. Bacterial activity and the distribution of tongue coating were quantitatively analyzed by dividing the tongue into six areas using the TB01 1.05 software. ROC curves were generated using MedCalc® software to validate the diagnosis of oral malodor, the testing of bacterial activity, and the distribution of tongue coating. Bacterial activity and the distribution of tongue coating showed a very strong association with each other (r = 0.937, p < 0.01), and were significantly higher in the oral malodor group (p < 0.05). The distribution of tongue coating was highly correlated with H2S (r = 0.223, p < 0.01) but not associated with CH3SH. Sensitivity, specificity, and the area under the curve confirmed the high accuracy of this method in assessing bacterial activity and the distribution of tongue coating in the diagnosis of oral malodor. Since QLF images provide significant accuracy during quantitative analysis in the identification of bacterial activity and the distribution of tongue coating, systematic management of tongue coating and reduced oral malodor can be achieved by actively using QLF images and oral malodor measurement.

Reciprocal inhibition of expression between RAV1 and BES1 modulates plant growth and development in Arabidopsis.

RAV1 (Related to ABI3/VP1) is a plant-specific B3 and AP2 domain-containing transcription factor that acts as a negative regulator of growth in many plant species. The expression of RAV1 is downregulated by brassinosteroids (BRs); large-scale transcriptome analyses have shown that the expression of RAV1 was previously targeted by BRI1-EMS-SUPPRESOR1 (BES1) and BRASSINAZOLE-RESISTANT1 (BZR1), which are critical transcription factors for the BR-signaling process. Using RAV1-overexpressing transgenic plants, we showed that RAV1 overexpression reduced the BR signaling capacity, resulting in the downregulation of BR biosynthetic genes and BES1 expression. Furthermore, we demonstrated that BES1, not BZR1, is directly bound to the RAV1 promoter and repressed RAV1 expression, and vice versa; RAV1 is also bound to the BES1 promoter and repressed BES1 expression. This mutual inhibition was specific to RAV1 and BES1 because RAV1 exhibited binding activity to the BZR1 promoter but did not repress BZR1 expression. We observed that constitutively activated BR signaling phenotypes in bes1-D were attenuated by the repression of endogenous BES1 expression in transgenic bes1-D plants overexpressing RAV1. RNA-sequencing analysis of RAV1-overexpressing transgenic plants and bes1-D mutant plants revealed differentially expressed genes by RAV1 and BES1 and genes that were oppositely co-regulated by RAV1 and BES1. RAV1 and BES1 regulated different transcriptomes but co-regulated a specific set of genes responsible for the balance between growth and defense. These results suggested that the mutual inhibitory transcriptional activities of RAV1 and BES1 provide fine regulatory mechanisms for plant growth and development.

Risk of dementia according to the severity of chronic periodontitis in Korea: a nationwide retrospective cohort study.

OBJECTIVES: We investigated the risk of dementia in older adults with chronic periodontitis according to the severity of periodontitis. METHODS: Data on patients with chronic periodontitis were extracted from the National Health Insurance Service-Senior cohort database from 2002 to 2014. Among 52,728 subjects eligible for inclusion, 11,953 subjects had newly diagnosed mild chronic periodontitis (MCP), and 40,775 subjects had newly diagnosed severe chronic periodontitis (SCP). Two 1:1 propensity score matched cohorts were created with 8,624 patients each in the MCP and SCP groups. To analyze the risk of dementia, a Cox proportional-hazard model was used to calculate hazard ratios with 95% confidence intervals (CIs). RESULTS: In the Kaplan-Meier curve, the disease-free probability was significantly lower in the SCP group than in the MCP group (p for log-rank=0.001). In the multivariable-adjusted model, the HR for the occurrence of dementia in the SCP group compared to the MCP group was 1.15 (95% CI, 1.04 to 1.27; p=0.009). A subgroup analysis revealed a significant association between dementia and the severity of periodontitis, especially in subjects who were male, aged ≥70 years, and had comorbidities. CONCLUSIONS: Reducing the severity of chronic periodontitis can help to reduce the risk of dementia. Therefore, it is necessary to aggressively conduct early dementia-prevention programs for males under the age of 70 that include dental health to prevent the progression of periodontitis from mild to severe.

Trend Analysis of Average Frequency Using Toothbrushing per Day in South Korea: An Observational Study of the 2010 to 2018 KNHANES Data.

The aim of this study was to examine the trend of average frequency of toothbrushing per day according to the sociodemographic characteristics using the 5th, 6th, and 7th Korean National Health and Nutrition Examination Survey (KNHANES) data for 9 years; from 2010 to 2018. It intends to understand the state of toothbrushing practices in South Korea, and to provide basic data for promoting toothbrushing practices. Data from the 5th, 6th, and 7th KNHANESs conducted by the Korean Disease Control and Prevention Agency each year was analyzed using IBM SPSS version 26.0 (IBM Co., Armonk, NY, USA). Tableau version 2020.1 was used for the graphs and geographic information system (GIS). The significance level of α was set at 0.05 for testing. In all analyses, the complex sampling analysis method with stratification variables, cluster variables, and weights was applied, and the complex sample linear regression analysis. The average frequency of toothbrushing per day was higher in women for all the years; these women belonged to the age group under 65 and the employed group. The average frequency of toothbrushing per day was lower in the married, elementary school graduate, part-time job, and low-income groups for all years. The demographic and social factors affecting the number of toothbrushing practices per day were gender, education level, income level, and work type. After analyzing the average frequency of toothbrushing per day in each of the cities and provinces, Gangwon-do and Jeonbuk showed the highest increase in the frequency of toothbrushing in 2018 compared to 2010, whereas Incheon showed the lowest increase. From the above results, the average frequency of toothbrushing per day was lower in males, those with a low education level, the unemployed, and those in the rural area for a period of 9 years. Therefore, in-depth oral health promotion projects and national benefit policies should be considered for effective toothbrushing education by identifying individuals who do not brush their teeth.

Association of Insufficient or Excess Sleep with Type 2 Diabetes Mellitus in the Presence of Periodontitis.

We aimed to investigate the effects of sleep duration on impaired fasting glucose and diabetes in Korean adults with periodontal disease. This cross-sectional study was performed using data for 10,465 subjects aged >19 years who completed the periodontal examination and questionnaires in the Sixth Korea National Health and Nutrition Examination Survey (2013-2015). The effect of sleep was confirmed by a complex-sample multinomial logistic regression analysis. Confounding variables were age, sex, household income, education level, smoking status, and sleep duration. Of all participants, 25.7% had periodontitis, of which 28.6% had fasting serum glucose disorder and 14.2% had diabetes. Among participants with periodontitis, the prevalence of diabetes was 1.49 times higher in participants with an average sleep duration of ≥8 h than those with an average sleep duration of 6-7 h. The prevalence of diabetes among participants without periodontitis was 1.49 times and 1.57 times higher in participants with an average sleep duration of ≤5 and ≥8 h, respectively, than those with an average sleep duration of 6-7 h. We found that altered sleep duration may be a risk factor for diabetes and that proper sleep duration is important to control diabetes incidence.

Association between Dental Treatment, Quality of Life, and Activity Limitation According to Masticatory Discomfort: Evidence from the Korean National Health and Nutrition Examination Survey (2013-2015).

People with masticatory discomfort are unable to consume a balanced diet, which impacts their general health. We studied the relationship between quality of life and dental care associated with masticatory discomfort. Data from Korea's representative 6th Korea National Health and Nutrition Examination Survey (KNHANES) were used. Complex sampling analysis with the stratification variable, clustering variable, and weight was applied. Demographic and dental treatment characteristics and activity limitations were compared through chi-square tests. The comparison of quality of life according to masticatory discomfort was performed using linear regression. The risk of masticatory discomfort was high in people who did not undergo regular oral examinations and preventive and definitive caries treatment and in those who received periodontal, surgical, endodontic, or prosthetic treatments. Generally, people with masticatory discomfort engaged in less activity owing to other disorders like arthritis, rheumatism, and back, neck, and oral disease. People with masticatory discomfort scored low on quality of life. People who received regular oral examinations and preventive care had a low level of masticatory discomfort, and the treated persons had high masticatory discomfort. Therefore, in order to reduce masticatory discomfort, more diverse and active care should be provided for prevention, specifically regular oral examinations.

Crosstalk between Fisetin-induced Apoptosis and Autophagy in Human Oral Squamous Cell Carcinoma.

Fisetin (3,3-,4-,7-tetrahydroxyflavone), a naturally occurring flavonoid, has antioxidant, anti-inflammatory, and anticancer effects. Oral squamous cell carcinoma (OSCC) has a 5-year survival rate lower than that of most other carcinomas, and can create functional and aesthetic problems for the patient. New therapies for OSCC are necessary, and treatment using plant-derived natural substances has recently become a trend. It has been suggested that autophagy may play an important role in cancer therapy. Several studies demonstrated that autophagy inhibition enhances apoptotic cell death. Therefore, autophagy inhibition might be a promising therapeutic method against OSCC. Our results showed that fisetin induced apoptotic cell death in human tongue squamous cell line Ca9-22 could be enhanced by inhibition of autophagy. Thus, autophagy process in fisetin treated OSCC might presumed to play a role of pro-survival. The combination of fisetin and an effective autophagy inhibitor could be a potentially adjuvant and useful treatment for oral cancer.

Delphinidin induces apoptosis and inhibits epithelial-to-mesenchymal transition via the ERK/p38 MAPK-signaling pathway in human osteosarcoma cell lines.

Delphinidin is major anthocyanidin that is extracted from many pigmented fruits and vegetables. This substance has anti-oxidant, anti-inflammatory, anti-angiogenic, and anti-cancer properties. In addition, delphinidin strongly suppresses the migration and invasion of various cancer cells during tumorigenesis. Although delphinidin has anti-cancer effects, little is known about its functional roles in osteosarcoma (OS). For these reasons, we have demonstrated the effects of delphinidin on OS cell lines. The effects of delphinidin on cell viability and growth of OS cells were assessed using the MTT assay and colony formation assays. Hoechst staining indicated that the delphinidin-treated OS cells were undergoing apoptosis. Flow cytometry, confocal microscopy, and a western blot analysis also indicated evidence of apoptosis. Inhibition of cell migration and invasion was found to be associated with epithelial-to-mesenchymal transition (EMT), observed by using a wound healing assay, an invasion assay, and a western blot analysis. Furthermore, delphinidin treatment resulted in a profound reduction of phosphorylated forms of ERK and p38. These findings demonstrate that delphinidin treatment suppressed EMT through the mitogen-activated protein kinase (MAPK) signaling pathway in OS cell lines. Taken together, our results suggest that delphinidin strongly inhibits cell proliferation and induces apoptosis. Delphinidin treatment also suppresses cell migration and prevents EMT via the MAPK-signaling pathway in OS cell lines. For these reasons, delphinidin has anti-cancer effects and can suppress metastasis in OS cell lines, and it might be worth using as an OS therapeutic agent.

Arabidopsis galactinol synthases 1 (AtGOLS1) negatively regulates seed germination.

Seed germination begins the growth phases of plants and its rate is affected not only by plant hormones, including abscisic acid (ABA), gibberellin (GA) and brassinosteroids (BRs), but also by environmental factors. In this study, we searched for additional chemical reagents that affect seed germination, using the det2-1 and ga1-3 mutants that showed reduced seed germination due to defective BR- or GA- biosynthesis, respectively. We found that the reducing reagent dithiothreitol (DTT) specifically enhanced seed germination of det2-1 compared with that of ga1-3. To further investigate the underlying molecular mechanism for this phenomenon, we identified AtGOLS1 as a differentially expressed gene in germinating seeds treated with DTT by GeneFishing analysis. AtGOLS1 encodes a galactinol synthase, critical for the first step in raffinose family oligosaccharides synthesis during seed maturation. We observed that expression of AtGOLS1 decreased when conditions were favorable for seed germination. We also determined that the seed germination rate was faster in T-DNA knockout atgols1 mutant and transgenic plants transformed with an RNA interference construct targeting AtGOLS1 compared with wild type plants. The double mutant of det2-1 and atgols1 also suppressed the reduced seed germination of the det2-1. Taken together, our results suggest that AtGOLS1 acts as a negative regulator in seed germination.

Stability Evaluation of National Reference Standards for Blood Products in Korea.

National reference standards (NRSs) for biologics are established through potency estimation by a multicenter joint study of standard materials used in the approval process for national lot release and quality control of vaccines, blood products, and other biologics. In this study, a stability evaluation was conducted to determine whether the potency of NRSs for six blood products was being maintained at a consistent level in Korea. The present study conducted real-time stability tests via in-vivo/in-vitro bioassay on NRSs for blood coagulation factor VIII concentrate (2nd standard), antithrombin concentrate, prekallikrein activator, anti-hepatitis B immunoglobulin, blood coagulation factor IX concentrate, and anti-tetanus human immunoglobulin, as well as a trend analysis using cumulative annual results. The real-time stability test results showed that the mean potency of six NRSs was all within the control limit. In the trend analysis, the potency of NRS for blood coagulation factor VIII concentrate (2nd standard) showed a decreasing trend, while the potency of all other products had been stably maintained. The present study confirmed that the mean potency of NRSs for six blood products had been stably maintained in Korea. The findings of the present study establish a foundation that can ensure the quality of NRSs for biologics in Korea, and it is expected to make a major contribution to the supply of high-quality biologics.

Reverse function of ROS-induced CBL10 during salt and drought stress responses.

Cellular levels of Ca(2+) and reactive oxygen species (ROS) are maintained at low levels in the cytosol but fluctuate greatly when acting as second messengers to decode environmental and developmental signals. Phytohormones are primary signals leading to various changes in ROS or Ca(2+) signaling during synergistic and antagonistic cross-talk. In this study, we found that brassinosteroids (BRs), hormones involved in diverse plant developmental processes, promote ROS production. To identify downstream signaling components of ROS during BR-mediated plant development, we searched for genes whose expression remained unchanged by ROS only in BR- signaling mutants and found calcineurin B-like (CBL) 10, which encodes a CBL should be changed to CBL10. protein that senses calcium. ROS-induced CBL10 expression was nullified and endogenous CBL10 expression in the shoot was low in the BR-signaling mutant. Using a cbl10 mutant and a transgenic plant overexpressing CBL10, we showed that BR sensitivity during hypocotyl growth decreased in the cbl10 mutant under salt stress, providing an additional mechanism for positive regulation of salt stress by CBL10. We also demonstrated that CBL10 negatively affects tolerance to drought and is not mediated by abscisic acid-induced signaling. Our results suggest that Ca(2+) signaling through CBL10 differently affects the response to abiotic stresses, partly by regulating BR sensitivity of plant tissues.

Detection of Carbapenemases in Clinical Enterobacteriaceae Isolates Using the VITEK AST-N202 Card.

BACKGROUND: The rapid and accurate detection of carbapenemase-producing Enterobacteriaceae (CPE) in clinical microbiology laboratories is essential for the treatment and control of infections caused by these microorganisms. This study was performed to evaluate the ability of the VITEK AST-N202 card to detect CPE isolates. MATERIALS AND METHODS: A total of 43 (Klebsiella pneumoniae, n = 37; Escherichia coli, n = 3; and Enterobacter cloacae, n = 3) CPE isolates and 79 carbapenemase-non-producing Enterobacteriaceae (CNE) isolates were included in this study. The CPE isolates harbored KPC-2 (n = 11), KPC-3 (n = 20), GES-5 (n = 5), VIM-2 (n = 2), IMP-1 (n = 1), NDM-1 (n = 2), or OXA-232 (n = 2). Of the 79 CNE isolates, eight K. pneumoniae isolates were resistant to ertapenem, imipenem, and meropenem, while the remaining 71 isolates were susceptible to the carbapenems. Antimicrobial susceptibilities were tested using the VITEK AST-N202 card, and the results were interpreted as positive when the isolates showed resistant or intermediate results. Modified-Hodge tests (MHTs) were performed using ertapenem or meropenem disks for the screening of carbapenemase production. Polymerase chain reaction (PCR) and direct sequencing were used to identify ß-lactamase genes. RESULTS: Sensitivity of MHT with ertapenem and meropenem disks for the detection of carbapenemase was 81.4% (35/43) and 81.4% (35/43), respectively, and a combination with both antibiotic disks increased the sensitivity to 88.4% (38/43). Specificity of the MHT was 100% (79/79) for the CNE isolates. Sensitivity of ertapenem, imipenem, and meropenem as assessed by the VITEK AST-N202 card was 100% (43/43), 93% (40/43), and 95.3% (41/43), respectively. Specificity (89.8%, 71/79) of the test with each carbapenem was improved to 100% (71/71) when eight carbapenem-resistant CNE isolates were excluded from the testing. CONCLUSION: The VITEK AST-N202 card showed high sensitivity for the detection of carbapenemases in Enterobacteriaceae strains. PCR and sequencing experiments for the detection of carbapenemases are recommended when clinical Enterobacteriaceae isolates show non-susceptibility to carbapenems.

Epidemiology and Characteristics of Metallo-ß-Lactamase-Producing Pseudomonas aeruginosa.

Metallo-ß-lactamase-producing Pseudomonas aeruginosa (MPPA) is an important nosocomial pathogen that shows resistance to all ß-lactam antibiotics except monobactams. There are various types of metallo-ß-lactamases (MBLs) in carbapenem-resistant P. aeruginosa including Imipenemase (IMP), Verona integron-encoded metallo-ß-lactamase (VIM), Sao Paulo metallo-ß-lactamase (SPM), Germany imipenemase (GIM), New Delhi metallo-ß-lactamase (NDM), Florence imipenemase (FIM). Each MBL gene is located on specific genetic elements including integrons, transposons, plasmids, or on the chromosome, in which they carry genes encoding determinants of resistance to carbapenems and other antibiotics, conferring multidrug resistance to P. aeruginosa. In addition, these genetic elements are transferable to other Gram-negative species, increasing the antimicrobial resistance rate and complicating the treatment of infected patients. Therefore, it is essential to understand the epidemiology, resistance mechanism, and molecular characteristics of MPPA for infection control and prevention of a possible global health crisis. Here, we highlight the characteristics of MPPA.

A hemagglutinin quantification method for development of an influenza pandemic vaccine using size exclusion high performance liquid chromatography.

Single radial immunodiffusion (SRID) assay requires a reference antigen and an antibody to the hemagglutinin (HA) of an influenza vaccine. As it takes 2­3 months to develop the reference antigen, vaccine development is delayed in cases of an influenza pandemic. In the present study, the measurement of the HA content of influenza vaccines was assessed using size exclusion high performance liquid chromatography (SE­HPLC) for the rapid development of a pandemic vaccine. When the 2009 H1N1 reference antigen, pandemic 2009 H1N1 vaccine and 2010 seasonal influenza vaccines were analyzed by SE­HPLC, the HA of the reference antigen and vaccines was specifically separated. The presence and specificity of HA were evidenced with immunoprecipitation and ELISA assays. For the influenza vaccines, the chromatogram pattern and retention time of HA were similar among the antigen types (2009 H1N1, 2010 H3N2 and 2010 B). In addition, when SE­HPLC was applied, the ratio of HA chromatogram to peak area revealed a significant correlation with HA concentration for the reference antigen and vaccine. The result of the HA content calculation based on SE­HPLC exhibited 99.91­100% similarity, compared with that of SRID. These findings suggest that the measurement of peak area ratio/HA content using SE­HPLC may be a substitute for SRID and rapidly measure HA content to enable faster development of a vaccine during an influenza pandemic.

A subset of Arabidopsis RAV transcription factors modulates drought and salt stress responses independent of ABA.

Arabidopsis RAV1, RAV1L and RAV2/TEM2 are Related to ABI3/VP1 (RAV) transcription factors that contain both plant-specific B3 and AP2 domains. RAV1 was known to be a negative regulator of growth and its transcript level was repressed by brassinolide (BL). In this study, we found that the expressions of RAV1, and its closest homologs RAV1L and RAV2 were also regulated by other plant hormones, and especially repressed significantly by BL and abscisic acid (ABA), which mediate various abiotic stress responses in plants. Therefore, to further investigate the physiological functions of RAV1, RAV1L and RAV2 in abiotic stress responses, we isolated T-DNA insertional knockout mutants of each gene and produced transgenic plants overexpressing the RAVs. Under normal conditions, each single mutant showed slightly promoted growth patterns only at an early stage of development. In comparison, the RAV1-overexpressing plants exhibited strong growth retardation with semi-dwarfed stature. In drought conditions, RAVs-overexpressing transgenic plants exhibited higher transpirational water loss than the wild type. In salt conditions, seed germination of the RAVs-overexpressing transgenic plants was more inhibited than that of the wild type, while ravs mutants showed promoted seed germination. We also found that RAVs expressions were reduced by dryness and salt. RAV1-overexpressing plants showed the same patterns of increased expression as stress-inducible genes such as RD29A, RD29B and the genes encoding ABA biosynthetic enzymes, as did the wild type and rav1 mutant. However, the RAV1-overexpressing transgenic plants were insensitive to ABA, regardless of the higher accumulation of ABA even in normal conditions. Taken together, these results suggest that RAVs are versatile negative regulators for growth and abiotic stresses, drought and salt, and that negative regulatory effects of RAVs on abiotic stresses are likely to be operated independently of ABA.

ß-Amino-n-butyric Acid Regulates Seedling Growth and Disease Resistance of Kimchi Cabbage.

Non-protein amino acid, ß-amino-n-butyric acid (BABA), has been involved in diverse physiological processes including seedling growth, stress tolerance and disease resistance of many plant species. In the current study, treatment of kimchi cabbage seedlings with BABA significantly reduced primary root elongation and cotyledon development in a dose-dependent manner, which adverse effects were similar to the plant response to exogenous abscisic acid (ABA) application. BABA was synergistically contributing ABA-induced growth arrest during the early seedling development. Kimchi cabbage leaves were highly damaged and seedling growth was delayed by foliar spraying with high concentrations of BABA (10 to 20 mM). BABA played roles differentially in in vitro fungal conidial germination, mycelial growth and conidation of necrotroph Alternaria brassicicola causing black spot disease and hemibiotroph Colletotrichum higginsianum causing anthracnose. Pretreatment with BABA conferred induced resistance of the kimchi cabbage against challenges by the two different classes of fungal pathogens in a dose-dependent manner. These results suggest that BABA is involved in plant development, fungal development as well as induced fungal disease resistance of kimchi cabbage plant.

Synergistic effects between silibinin and antibiotics on methicillin-resistant Staphylococcus aureus isolated from clinical specimens.

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous microorganism, and creates serious medical problems. It causes many types of infections in humans and often acquires multi-drug resistance. In this study, silibinin was evaluated against 20 clinical isolates of MRSA, either alone or in combination with ampicillin or oxacillin, using a checkerboard assay. The silibinin exhibited good activity against isolates of MRSA, and MRSA ATCC33952 and MSSA ATCC25923, with minimum inhibitory concentrations/minimum bactericidal concentrations (MICs/MBCs) ranging between 2-8/4-16 µg/mL, for ampicillin 2-1024/2-2048 µg/mL, and for oxacillin 0.25-32/0.5-64 µg/mL. The range of MIC(50) and MIC(90) were 0.5-4 µg/mL and 2-8 µg/mL, respectively. The MICs/MBCs for the combination of silibinin plus oxacillin or ampicillin were reduced by ≥4-fold against the MRSA isolates tested, demonstrating a synergistic effect, as defined by a fractional inhibitory concentration index (FICI) of ≤0.5. Furthermore, a time-kill study evaluating the growth of the tested bacteria showed that growth was completely attenuated after 2-5 h of treatment with the 1/2 MIC of silibinin, regardless of whether it was administered alone or with oxacillin (1/2 MIC) or ampicillin (1/2 MIC). In conclusion, silibinin exerted synergistic effects when administered with oxacillin or ampicillin and the antibacterial activity and resistant regulation of silibinin against clinical isolates of MRSA might be useful in controlling MRSA infections.

Prevalence of the extended-spectrum beta-lactamase and qnr genes in clinical isolates of Escherichia coli.

BACKGROUND: This study was performed to investigate the prevalence of qnr genes in clinical isolates of Escherichia coli from Korea that produce extended-spectrum beta-lactamases (ESBLs). METHODS: During the period of May to June 2005, we collected clinical isolates of E. coli that were intermediate or resistant to ceftazidime and/or cefotaxime from 11 Korean hospitals. Antimicrobial susceptibility was determined by the disk diffusion and agar dilution methods. ESBL production was confirmed phenotypically by the double-disk synergy test. ESBL and qnr genes were searched for by PCR amplification, and the PCR products were then subjected to direct sequencing. RESULTS: Double-disk synergy tests were positive in 84.3% (118/140) of ceftazidime- and/or cefotaxime-nonsusceptible E. coli isolates. The most prevalent types of ESBL in E. coli isolates were CTX-M-14 (N=41) and CTX-M-15 (N=58). Other ESBLs were also identified, including CTX-M-3 (N=7), CTX-M-9 (N=8), CTX-M-12 (N=1), CTX-M-57 (N=1), SHV-2a (N=2), SHV-12 (N=17) and TEM-52 (N=4). The qnrA1 and qnrB4 genes were identified in 4 and 7 ESBL-producing isolates, respectively. CONCLUSIONS: CTX-M-type enzymes were the most common type of ESBL in E. coli isolates from Korea, and the qnr genes were not uncommon in ESBL-producing E. coli isolates. Dissemination of E. coli containing both ESBL and qnr genes could compromise the future usefulness of the expanded-spectrum antibiotics for the treatment of infections.

Inhibitory effects of costunolide on the telomerase activity in human breast carcinoma cells.

Costunolide, a natural sesquiterpene compound, has been known having cytotoxic and chemopreventive effects on various human cancer cells. In the present study, we examined the effects of costunolide on telomerase activity and on the components of telomerase in MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) cells. We found that costunolide inhibited the growth and telomerase activity of MCF-7 and MDA-MB-231 cells in a concentration- and time-dependent manner. The expression of hTERT mRNA was also inhibited but hTR mRNA was not. In addition, the bindings of transcription factors in hTERT promoters were significantly decreased in both cells by the treatment of costunolide. These results suggest that costunolide inhibited the growth of both MCF-7 and MDA-MB-231 cells and this effect was mediated at least in part by a significant reduction in telomerase activity.