• The Journal of the Korean Society for Microbiology
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• v.35 no.3
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• pp.215-224
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• 2000

In this study, the distribution of the mec regulator genes and the presence of the mutation in mecI gene and mec promoter region among 50 MRSA clinical isolates derived from a single university hospital in Korea were analyzed. Among 50 MRSA strains, 13 strains had a deletion of mecI gene, and 37 strains were found to have mutations in mecI gene or mecA promoter region corresponding to a presumptive operator of mecA, i.e., the binding site of the repressor protein. Furthermore, in order to track the evolution of methicillin-resistant Staphylococcus aureus (MRSA) distributed in Korea, we determined the MRSA clonotype by combined use of genetic organization patterns of mec regulator genes, ribotype, and coagulase type. As the result, 48 of 50 MRSA strains could be classified into four distinct clones. Clonotype I is characterized by the coagulase type 3, deletion of mecI gene, and ribotype 1 shared by NCTC10442, the first reported MRSA isolate in England (9 strains). Clonotype II is characterized by the coagulase type 4, C to T substitution at position 202 of mecI gene, and ribotypes 2, 3 and 4 shared by 85/3619 strain isolated in Austria (10 strains). Clonotype III is characterized by the coagulase type 2, mutations of mecA promoter region and/or mecI, and ribotypes 4, 5, and 6 shared by N315 strain isolated in Japan (25 strains). Clonotype IV is characterized by the coagulase type 4, deletion of mecI gene, and ribotype 7 (4 strains). The clonality of two strains could not be determined due to their undefined ribotype.

• Journal of Life Science
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• v.11 no.1
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• pp.24-34
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• 2001

Methicillin Resistant Staphylococcus aureus (MRSA) was obtained from the clinical specimens at Pusan national university Hospital, Pusan, Korea. The sensitivities against various antibiotics were examined by using disc diffusion test and associated genes such as mecA, mecR1, mecI and femA were detected by polymerase chain reaction. Among Seventy-nine strains of MRSA, 38 strains(48.1%)were sensitive to streptomycin and 32 strains(40.5%) to cefoperazone, while one strain(1.3%) were resistant to vancomycin. In considering the result of this study, 7 strains showed resistance to 9 kinds of different antibiotics, 12 strains were to 8 kinds, 24 strains were to 7,25 strains were to 6, 9 strains were to 5, and 2 strains were to 4 antibiotics. Among 79 strains of MRSA, 67 strains were coagulase positive and 12 were coagulase negative. In the detection of MRSA associated genes by PCR method, mecA, mecR1, mecI, and femA genes were detected in 30 strains(44.8%), 28 strains(41.8%), 23 strains(34.3%) and 15 strains(22.4%), respectively. MecA type that is without femA were found in 21 strains(31.3%), femA type that is without regulator genes were shown in 4 strains(6.0%), while mecA-mecR1-mecI type with regulator genes were shown more to be 17 strains(25.4%). There was little statistical significance between multidrug resistance and MRSA associated genes. Considering these result, it is necessary to include moecular biological studies of related genes to the study drug resistance.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.24-32
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• 2003

Purpose : Nosocomial infection with Staphylococcus aureus, especially methicillin resistant S. aureus, has become a serious concern in the neonatal intensive care unit. The aim of this study is to investigate the virulence factors, and the relationship between the antibiotic resistance and the associated genes of Staphylococcus aureus isolated from nasal cavity of neonates. Methods : Fifty one isolates of S. aureus were obtained from nasal swab taken in 28 neonates in the NICU and nursery of Pusan National University Hospital between February and May, 2001. They were tested in regard to antibiotic susceptibility, coagulase test and typing, plasmid DNA profile, as well as reactivity to enterotoxin A-E(sea, seb, sec, sed, see) genes and toxic shock syndrome toxin-1(tst) gene by polymerase chain reaction(PCR). Associated genes such as mecA, mecR1, mecI, and femA were also determined by PCR. The origin of MRSA strains was assessed using DNA fingerprinting by arbitrarily-primed polymerase chain reaction(AP-PCR). Results : Twenty three(45.1%) and six(11.8%) isolates were resistant to oxacillin and vancomycin respectively. Multidrug resistance to three or more of the antibiotics tested was observed in 51.0% of the isolates. Forty two isolates were coagulase positive and twenty two isolates had mecA gene. Sixteen isolates had both mecA and femA genes and had type I-III plasmids. 64.7% of isolates carried sec gene, and 80.4% carried tst gene. DNA fingerprinting by AP-PCR for 12 MRSA strains showed 10 distinct patterns, suggesting different origins. Conclusion : We confirmed that the prevalence of nasal carriage of S. aureus and the incidence of antimicrobial-resistant S. aureus, especially vancomycin resistance, is very high in neonates who were admitted in NICU and nursery. It is possible that these pathogens are responsible for serious nosocomial infections in neonates. The need for improved surveillance and continuous control of pathogens is emphasized.

• Electronics and Telecommunications Trends
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• v.37 no.4
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• pp.46-59
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• 2022

The 5G MEC (Multi-access Edge Computing) technology offers network and computing functionalities that allow application services to improve in terms of network delay, bandwidth, and security, by locating the application servers closer to the users at the edge nodes within the 5G network. To offer its interoperability within various networks and user equipment, standardization of the 5G MEC technology has been advanced in ETSI, 3GPP, and ITU-T, primarily for the MEC platform, transport support, and MEC federation. This article offers a brief review of the standardization activities for 5G MEC technology and the details about the system architecture and functionalities developed accordingly.

• Journal of Microbiology and Biotechnology
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• v.30 no.3
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• pp.469-475
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• 2020

During meiosis I, programmed DNA double-strand breaks (DSBs) occur to promote chromosome pairing and recombination between homologs. In Saccharomyces cerevisiae, Mec1 and Tel1, the orthologs of human ATR and ATM, respectively, regulate events upstream of the cell cycle checkpoint to initiate DNA repair. Tel1^ATM and Mec1^ATR are required for phosphorylating various meiotic proteins during recombination. This study aimed to investigate the role of Tel1^ATM and Mec1^ATR in meiotic prophase via physical analysis of recombination. Tel1^ATM cooperated with Mec1^ATR to mediate DSB-to-single end invasion transition, but negatively regulated DSB formation. Furthermore, Mec1^ATR was required for the formation of interhomolog joint molecules from early prophase, thus establishing a recombination partner choice. Moreover, Mec1^ATR specifically promoted crossover-fated DSB repair. Together, these results suggest that Tel1^ATM and Mec1^ATR function redundantly or independently in all post-DSB stages.

• Journal of Yeungnam Medical Science
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• v.38 no.2
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• pp.169-174
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• 2021

Mucoepidermoid carcinoma (MEC) is the most common malignant neoplasm of the salivary gland, but primary thyroid MEC has rarely been reported and usually has a good prognosis. Herein, I report a case of thyroidal MEC with a poor prognosis in an 82-year-old woman with an anterior neck mass. Ultrasonography and computed tomography revealed a thyroid mass. The patient initially underwent fine-needle aspiration, was diagnosed with malignancy, and underwent a right lobectomy. On gross examination, a 4.0×3.6×2.6 cm-sized ill-defined, unencapsulated, and infiltrative tan to whitish mass with necrosis was identified. Microscopically, epidermoid tumor cell nests or solid sheets were identified. Mucous cells that were positive for periodic acid-Schiff and mucicarmine stains were also identified within epidermoid cell nests. Frequent mitosis and necrosis were observed. Immunohistochemical staining for p40 and p63 was positive, and that for thyroid transcription factor-1 and paired box gene 8 was focally positive. According to the Armed Forces Institute of Pathology grading system for salivary gland MEC, the current case was classified as high-grade MEC. After surgery, the patient suffered from dyspnea due to a remnant neck mass that compressed and obstructed the trachea; therefore, the patient refused further treatment. Thyroidal MECs are considered low-grade with a favorable prognosis, but there are several reported cases of thyroidal MEC with poor prognosis. The current case is a rare presentation of high-grade thyroidal MEC with a poor prognosis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4025-4041
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• 2020

Mobile edge computing (MEC) is capable of providing services to smart devices nearby through radio access networks and thus improving service experience of users. In this paper, an offloading strategy for the joint optimization of computing and communication resources in multi-user and multi-MEC overlapping scene was proposed. In addition, under the condition that wireless transmission resources and MEC computing resources were limited and task completion delay was within the maximum tolerance time, the optimization problem of minimizing energy consumption of all users was created, which was then further divided into two subproblems, i.e. offloading strategy and resource allocation. These two subproblems were then solved by the game theory and Lagrangian function to obtain the optimal task offloading strategy and resource allocation plan, and the Nash equilibrium of user offloading strategy games and convex optimization of resource allocation were proved. The simulation results showed that the proposed algorithm could effectively reduce the energy consumption of users.

• International Journal of Oral Biology
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• v.44 no.2
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• pp.55-61
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• 2019

The purpose of this study was to evaluate the effect of mangosteen extract complex (MEC; Garcinia mangostana L. and propolis extracts) on the inhibition of inflammation and prevention of alveolar bone loss using a ligature-induced periodontitis model. Rat molars were ligatured with silk, and $1{\mu}g/mL$ of lipopolysaccharide of Porphyromonas gingivalis was injected into the buccal and palatal gingivae of the teeth with or without treatment with the MEC. Changes in the expression levels of prostaglandin $E_2$ ($PGE_2$), interleukin-8 (IL-8), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-8 (MMP-8), cyclooxygenase (COX)-1, and COX-2 in gingival tissues were evaluated using enzyme-linked immunosorbent assays. Alveolar bone loss around the ligated molars was examined using micro-computed tomography. The expression levels of $PGE_2$, IL-8, iNOS, MMP-8, COX-1, and COX-2 in gingival tissues were significantly reduced in the group treated with a mixture of $16{\mu}g$ of mangosteen extract powder and $544{\mu}g$ of propolis extract powder (ligation [Lig] + lipopolysaccharide extracted from P. gingivalis KCOM 2804 [L] + MEC 1:34). Additionally, alveolar bone loss was significantly reduced in the Lig + L + MEC 1:34 group compared with that in other groups. These results indicate that the MEC could be useful in preventing and treating periodontitis.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.335-340
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• 2013

The antimicrobial effect of the methanol extract of Inula britannica flowers against methicillin resistant Staphylococcus aureus (MRSA) was investigated. It was confirmed that the methanol extract is mainly composed of quercetin, which has antimicrobial properties. The antimicrobial effect of the methanol extract against 3 MRSA strains was determined by the disc diffusion method. The minimal inhibitory concentrations were ranged from 0.625 mg/ml to 1.25 mg/ml, and the minimum bactericidal concentrations were 2.5 mg/ml. Time kill kinetics revealed bactericidal activities, and the morphological alterations in S. aureus ATCC 33591 treated with the extract were observed using a scanning electron microscope. The methanol extract affected the expression of the resistant genes, mecA, mecI, and mecRI in mRNA. Therefore, the methanol extract of I. britannica flowers clearly demonstrated an antimicrobial effect against MRSA and these results suggest a potential for application as a natural antimicrobial agent.

• Korean Journal of Veterinary Service
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• v.33 no.3
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• pp.233-240
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• 2010

Methicillin-resistant coagulase-negative staphylococci (MRCNS) were isolated from the respiratory sites of chickens in 4 farms and slaughter house located in Chungnam provinces. Isolation of coagulase-negative staphylococci (CNS) was positive for 61 (26.6%) of the 229 chickens tested, and isolation of MRCNS was positive for 17 (27.9%) of the isolated CNS. A total of 17 MRCNS isolates were selected and subjected to identification. Of the 17 MRCNS isolates selected, 6 were identified as Staphylococcus cohnii, 2 as S. saprophyticus, 3 as S. simulans, 3 as S. lentus, 2 as S. carnosus, and 1 as S. xylosus. The MRCNS isolates were resistant to many beta-lactam antibiotics, and some isolates were also resistant to macrolide and aminoglycoside antibiotics. The mecA gene was detected in some isolates of each MRCNS strains. The mecA-positive isolates were classified into five staphylococcal cassette chromosome mec (SCCmec). SCCmec types I to IV were detected in isolates from chickens.