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1
Umami, Zahra, Asri Indahning Warni, and Dewi Wahyuni. "mec Genes in Methicillin Resistant Staphylococcus aureus." Journal of Islamic Pharmacy 8, no. 2 (December 31, 2023): 78–82. http://dx.doi.org/10.18860/jip.v8i2.24060.
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Methicillin-resistant Staphylococcus aureus (MRSA) manifests antibiotic resistance, especially for the β-lactams antibiotic group. MRSA bacteria are a common cause of infection in humans. The antibiotic resistance characteristic comes from the mecA, mecB, and mecC genes in the bacterial chromosome. mecA is the most common gene found in MRSA. Therefore, it is essential to know the role of the mecA gene in antibiotic resistance. This paper searched the literature about MRSA bacteria, the mec gene, and their relationship to cause resistance. The results showed that the mec gene found in MRSA bacteria causes antibiotic resistance in penicillin groups. Methicillin-resistant Staphylococcus aureus (MRSA) manifests antibiotic resistance, especially for the β-lactams antibiotic group. MRSA bacteria are a common cause of infection in humans. The antibiotic resistance characteristic comes from the mecA, mecB, and mecC genes in the bacterial chromosome. mecA is the most common gene found in MRSA. Therefore, it is essential to know the role of the mecA gene in antibiotic resistance. This paper searched literature about MRSA bacteria, the mec gene, and their relationship to cause resistance. The results showed that the mec gene found in MRSA bacteria causes antibiotic resistance in penicillin groups.
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Cummins, Struan J. W., H. Putri Fraser, J. Robin Fulton, Martyn P. Coles, and Christopher M. Fitchett. "Coordination of β-Ketoimine-Derived Ligands at Main Group and Transition Metals." Australian Journal of Chemistry 68, no. 4 (2015): 641. http://dx.doi.org/10.1071/ch14546.
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The β-ketoimine HC[MeC(O)][MeC(NHt-Bu)] (1H) (Me = methyl) was used as a ligand in the synthesis of organo-aluminium and gallium compounds. With Al, the NH functionality was deprotonated to form the N,O-chelating β-ketoiminate ligand in Al{HC[MeC(O)][MeC(Nt-Bu)]}Me2 (3) (t-Bu = tertiary butyl), whereas the neutral form coordinated to trimethylgallium via the oxygen atom to form the adduct GaMe3·{HC[MeC(O)][MeC(NHt-Bu)]} (4). Reaction of 1H with Ar†NH2 (Ar† = 2-t-BuC6H4) afforded the new N-aryl β-ketoimine HC[MeC(O)][MeC(NHAr†)] (2H), which reacted with Pd(OAc)2 (OAc = acetate = CH3CO2–) to afford the heteroleptic dimer {Pd[HC(MeC(O))(MeC(NAr†))](μ-OAc)}2 ([5]2). The homoleptic bis(β-ketoiminate) Pd{HC[MeC(O)][MeC(NAr†)]}2 (6) was isolated as a minor product of this reaction. The crystal structures of compounds 3, 4, [5]2, and 6 are reported.
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Yamanaka, Shunpei, Susumu Suzuki, Hideaki Ito, Karnan Sivasundaram, Ichiro Hanamura, Ikuko Okubo, Kazuhiro Yoshikawa, et al. "Establishment of Mucoepidermoid Carcinoma Cell Lines from Surgical and Recurrence Biopsy Specimens." International Journal of Molecular Sciences 24, no. 2 (January 15, 2023): 1722. http://dx.doi.org/10.3390/ijms24021722.
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Patients with advanced/recurrent mucoepidermoid carcinoma (MEC) have a poor prognosis. This study aimed to establish and characterize human mucoepidermoid carcinoma cell lines from the initial surgical specimen and biopsy specimen upon recurrence from the same patient to provide a resource for MEC research. MEC specimens from the initial surgical procedure and biopsy upon recurrence were used to establish cell lines. The established cell lines were cytogenetically characterized using multi-color fluorescence in situ hybridization and detection, and the sequence of the CRTC1-MAML2 chimeric gene was determined. Furthermore, the susceptibility of head and neck mucoepidermoid carcinoma to standard treatment drugs such as cisplatin, 5-fluorouracil, and cetuximab was investigated. We successfully established unique MEC cell lines, AMU-MEC1, from an initial surgical specimen and AMU-MEC1-R1 and AMU-MEC1-R2 from the recurrent biopsy specimen in the same patient. These cell lines exhibited epithelial morphology and developed in vitro-like cobblestones. They shared eight chromosomal abnormalities, including der(19)ins(19;11)(p13;?), which resulted in a chimeric CRTC1-MAML2 gene, indicating the same origin of the cell lines. The susceptibility of all cell lines to cisplatin and 5-fluorouracil was low. Interestingly, EGFR dependency for cell growth decreased in AMU-MEC-R1 and AMU-MEC-R2 but was retained in AMU-MEC1. These cytogenetic and biochemical findings suggest that the established cell lines can be used to investigate the disease progression mechanisms and develop novel therapeutics for MEC.
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Koomson, Desmond Ato, Jingyu Huang, Guang Li, Nicholas Miwornunyuie, David Ewusi-Mensah, Williams Kweku Darkwah, and Prince Atta Opoku. "Comparative Studies of Recirculatory Microbial Desalination Cell–Microbial Electrolysis Cell Coupled Systems." Membranes 11, no. 9 (August 27, 2021): 661. http://dx.doi.org/10.3390/membranes11090661.
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The recirculatory microbial desalination cell–microbial electrolysis cell (MDC–MEC) coupled system is a novel technology that generates power, treats wastewater, and supports desalination through eco-friendly processes. This study focuses on the simultaneous efficient removal of Fe2+ and Pb2+ in the MEC and ammonium ions in the MDC. It also evaluates the performances of dual-chambered MEC (DCMEC) and single-chambered MEC (SCMEC), coupled with MDC with Ferricyanide as catholyte (MDCF) in heavy metals (Pb2+ and Fe2+) removal, in addition to the production of voltage, current, and power within a 48-h cycle. The SCMEC has a higher Pb2+ (74.61%) and Fe2+ (85.05%) removal efficiency during the 48-h cycle than the DCMEC due to the simultaneous use of microbial biosorption and the cathodic reduction potential. The DCMEC had a higher current density of 753.62 mAm−2 than that of SCMEC, i.e., 463.77 mAm−2, which influences higher desalination in the MDCF than in the SCMEC within the 48-h cycle. The MDCF produces a higher voltage (627 mV) than Control 1, MDC (505 mV), as a power source to the two MECs. Stable electrolytes’ pH and conductivities provide a conducive operation of the coupled system. This study lays a solid background for the type of MDC–MEC coupled systems needed for industrial scale-up.
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Fang, Juan, Jiamei Shi, Shuaibing Lu, Mengyuan Zhang, and Zhiyuan Ye. "An Efficient Computation Offloading Strategy with Mobile Edge Computing for IoT." Micromachines 12, no. 2 (February 17, 2021): 204. http://dx.doi.org/10.3390/mi12020204.
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With the rapidly development of mobile cloud computing (MCC), the Internet of Things (IoT), and artificial intelligence (AI), user equipment (UEs) are facing explosive growth. In order to effectively solve the problem that UEs may face with insufficient capacity when dealing with computationally intensive and delay sensitive applications, we take Mobile Edge Computing (MEC) of the IoT as the starting point and study the computation offloading strategy of UEs. First, we model the application generated by UEs as a directed acyclic graph (DAG) to achieve fine-grained task offloading scheduling, which makes the parallel processing of tasks possible and speeds up the execution efficiency. Then, we propose a multi-population cooperative elite algorithm (MCE-GA) based on the standard genetic algorithm, which can solve the offloading problem for tasks with dependency in MEC to minimize the execution delay and energy consumption of applications. Experimental results show that MCE-GA has better performance compared to the baseline algorithms. To be specific, the overhead reduction by MCE-GA can be up to 72.4%, 38.6%, and 19.3%, respectively, which proves the effectiveness and reliability of MCE-GA.
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Akkurt, Ramazan, and Mehmet Fatih Tuysuz. "5G-destekli Mobil Uç Hesaplama Çerçevesi." Academic Perspective Procedia 2, no. 3 (November 22, 2019): 874–83. http://dx.doi.org/10.33793/acperpro.02.03.99.
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Nowadays, mobile devices have increased rapidly due to the fact that devices connected to the Internet become more portable and can respond to user requests remotely. With this increase, the workload of mobile devices has also increased. However, it is sometimes impossible for mobile devices with limited resources to evaluate some critical and large transactions locally on their own and hence, it may adversely affect the user experience. The MEC (Mobile Edge Computing) system, which enables these processes to be evaluated and returned to the device faster and more efficiently, is now made possible with the 5G-network technology. The MEC concept differs from the previous MCC (Mobile Cloud Computing) system. In this study, the content of the basic MEC system such as the comparison of the MEC system with the MCC, the advantages it offers to mobile devices, usage cases, offloading scenarios, effective resource allocation and mobility management are discussed. In addition, in the scope of the study, high performance studies using MEC system effectively in the literature were examined.
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Shukla, Sanjay K., Srinivas V. Ramaswamy, Jennifer Conradt, Mary E. Stemper, Robert Reich, Kurt D. Reed, and Edward A. Graviss. "Novel Polymorphisms in mec Genes and a New mec Complex Type in Methicillin-Resistant Staphylococcus aureus Isolates Obtained in Rural Wisconsin." Antimicrobial Agents and Chemotherapy 48, no. 8 (August 2004): 3080–85. http://dx.doi.org/10.1128/aac.48.8.3080-3085.2004.
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ABSTRACT We determined allelic polymorphisms in the mec complexes of 524 methicillin-resistant Staphylococcus aureus isolates by partial or complete sequencing of three mec genes, mecA, mecI, and mecR1. The isolates had been collected over a 10-year period from patients living in rural Wisconsin, where the use of antibiotics was expected to be lower than in the bigger cities. Of the 18 mutation types identified, 16 had not been described previously. The five most common mutations were a mutation 7 nucleotides (nt) upstream from the start site (G→T) in the mecA promoter (34.7%), an E246G change encoded by mecA (2.2%), a cytosine insertion at codon 257 in mecA (13.2%), an N121K change encoded by mecI (7.8%), and a major mecI-mecR1 deletion designated as a class B1 mec complex deletion type (25.4%). There was a high degree of conservation of the amino acid sequence of MecR1. Strains with the same mutations had variable resistance to oxacillin, and the median MIC for isolates that harbored the 7-nt-upstream mutation was lower than that for strains harboring other mutations. Our data suggest that the mecA promoter mutation plays a more important role in determining methicillin resistance than mutations in mecI and mecA do. Eighty-five percent of the tested isolates (n = 148) with the mecA promoter mutation and the class B1 mec complex deletion belonged to the same major clonal group, identified as MCG-2, and harbored the type IV staphylococcal cassette chromosome mec DNA. There was also a wide range of oxacillin MICs for strains with wild-type mecA, mecI, and mecR1 sequences, suggesting that the genetic backgrounds of clinical strains are significant in determining susceptibility to methicillin.
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Peng, Kai, Victor C. M. Leung, Xiaolong Xu, Lixin Zheng, Jiabin Wang, and Qingjia Huang. "A Survey on Mobile Edge Computing: Focusing on Service Adoption and Provision." Wireless Communications and Mobile Computing 2018 (October 10, 2018): 1–16. http://dx.doi.org/10.1155/2018/8267838.
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Mobile cloud computing (MCC) integrates cloud computing (CC) into mobile networks, prolonging the battery life of the mobile users (MUs). However, this mode may cause significant execution delay. To address the delay issue, a new mode known as mobile edge computing (MEC) has been proposed. MEC provides computing and storage service for the edge of network, which enables MUs to execute applications efficiently and meet the delay requirements. In this paper, we present a comprehensive survey of the MEC research from the perspective of service adoption and provision. We first describe the overview of MEC, including the definition, architecture, and service of MEC. After that we review the existing MUs-oriented service adoption of MEC, i.e., offloading. More specifically, the study on offloading is divided into two key taxonomies: computation offloading and data offloading. In addition, each of them is further divided into single MU offloading scheme and multi-MU offloading scheme. Then we survey edge server- (ES-) oriented service provision, including technical indicators, ES placement, and resource allocation. In addition, other issues like applications on MEC and open issues are investigated. Finally, we conclude the paper.
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Garibay, Ángel María. "Mec." Tlalocan 2, no. 3 (September 28, 2016): 278–79. http://dx.doi.org/10.19130/iifl.tlalocan.1947.429.
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Ito, Teruyo, Xiao Xue Ma, Fumihiko Takeuchi, Keiko Okuma, Harumi Yuzawa, and Keiichi Hiramatsu. "Novel Type V Staphylococcal Cassette Chromosome mec Driven by a Novel Cassette Chromosome Recombinase, ccrC." Antimicrobial Agents and Chemotherapy 48, no. 7 (July 2004): 2637–51. http://dx.doi.org/10.1128/aac.48.7.2637-2651.2004.
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ABSTRACT Staphylococcal cassette chromosome mec (SCCmec) is a mobile genetic element composed of the mec gene complex, which encodes methicillin resistance, and the ccr gene complex, which encodes the recombinases responsible for its mobility. The mec gene complex has been classified into four classes, and the ccr gene complex has been classified into three allotypes. Different combinations of mec gene complex classes and ccr gene complex types have so far defined four types of SCCmec elements. Now we introduce the fifth allotype of SCCmec, which was found on the chromosome of a community-acquired methicillin-resistant Staphylococcus aureus strain (strain WIS [WBG8318]) isolated in Australia. The element shared the same chromosomal integration site with the four extant types of SCCmec and the characteristic nucleotide sequences at the chromosome-SCCmec junction regions. The novel SCCmec carried mecA bracketed by IS431 (IS431-mecA-ΔmecR1-IS431), which is designated the class C2 mec gene complex; and instead of ccrA and ccrB genes, it carried a single copy of a gene homologue that encoded cassette chromosome recombinase. Since the open reading frame (ORF) was found to encode an enzyme which catalyzes the precise excision as well as site- and orientation-specific integration of the element, we designated the ORF cassette chromosome recombinase C (ccrC), and we designated the element type V SCCmec. Type V SCCmec is a small SCCmec element (28 kb) and does not carry any antibiotic resistance genes besides mecA. Unlike the extant SCCmec types, it carries a set of foreign genes encoding a restriction-modification system that might play a role in the stabilization of the element on the chromosome.
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Chambers, H. F. "Methicillin resistance in staphylococci: molecular and biochemical basis and clinical implications." Clinical Microbiology Reviews 10, no. 4 (October 1997): 781–91. http://dx.doi.org/10.1128/cmr.10.4.781.
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Methicillin resistance in staphylococci is determined by mec, composed of 50 kb or more of DNA found only in methicillin-resistant strains. mec contains mecA, the gene for penicillin-binding protein 2a (PBP 2a); mecI and mecR1, regulatory genes controlling mecA expression; and numerous other elements and resistance determinants. A distinctive feature of methicillin resistance is its heterogeneous expression. Borderline resistance, a low-level type of resistance to methicillin exhibited by strains lacking mecA, is associated with modifications in native PBPs, beta-lactamase hyperproduction, or possibly a methicillinase. The resistance phenotype is influenced by numerous factors, including mec and beta-lactamase (bla) regulatory elements, fem factors, and yet to be identified chromosomal loci. The heterogeneous nature of methicillin resistance confounds susceptibility testing. Methodologies based on the detection of mecA are the most accurate. Vancomycin is the drug of choice for treatment of infection caused by methicillin-resistant strains. PBP 2a confers cross-resistance to most currently available beta-lactam antibiotics. Investigational agents that bind PBP 2a at low concentrations appear promising but have not been tested in humans. Alternatives to vancomycin are few due to the multiple drug resistances typical of methicillin-resistant staphylococci.
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Higashide, Masato, Makoto Kuroda, Carlos Takashi Neves Omura, Miyuki Kumano, Saburo Ohkawa, Sadahiro Ichimura, and Toshiko Ohta. "Methicillin-Resistant Staphylococcus saprophyticus Isolates Carrying Staphylococcal Cassette Chromosome mec Have Emerged in Urogenital Tract Infections." Antimicrobial Agents and Chemotherapy 52, no. 6 (March 24, 2008): 2061–68. http://dx.doi.org/10.1128/aac.01150-07.
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ABSTRACT Staphylococcus saprophyticus is a uropathogenic bacterium that causes acute uncomplicated urinary tract infections, particularly in female outpatients. We investigated the dissemination and antimicrobial susceptibilities of 101 S. saprophyticus isolates from the genitourinary tracts of patients in Japan. Eight of these isolates were mecA positive and showed β-lactam resistance. Pulsed-field gel electrophoresis showed that only some isolates were isogenic, indicating that the mecA gene was apparently acquired independently by mecA-positive isolates through staphylococcal cassette chromosome mec (SCCmec). Type determination of SCCmec by multiplex PCR showed a nontypeable element in the eight mecA-positive isolates. Sequence analysis of the entire SCCmec element from a prototype S. saprophyticus strain revealed that it was nontypeable with the current SCCmec classification due to the novel composition of the class A mec gene complex (IS431-mecA-mecR1-mecI genes) and the ccrA1/ccrB3 gene complex. Intriguingly, the attachment sites of SCCmec are similar to those of type I SCCmec in S. aureus NCTC 10442. Furthermore, the genes around the mec gene complex are similar to those of type II/III SCCmec in S. aureus, while those around the ccr gene complex are similar to those of SCC15305RM found in S. saprophyticus ATCC 15305. In comparison with known SCCmec elements, this S. saprophyticus SCCmec is a novel type.
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Oliveira, Duarte C., and Hermínia de Lencastre. "Multiplex PCR Strategy for Rapid Identification of Structural Types and Variants of the mec Element in Methicillin-Resistant Staphylococcus aureus." Antimicrobial Agents and Chemotherapy 46, no. 7 (July 2002): 2155–61. http://dx.doi.org/10.1128/aac.46.7.2155-2161.2002.
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ABSTRACT Full characterization of methicillin-resistant Staphylococcus aureus (MRSA) requires definition of not only the bacterial genetic background but also the structure of the complex and heterologous mec element these bacteria carry, which is associated with drug resistance determinant mecA. We report the development, validation, and application of a multiplex PCR strategy that allows quick presumptive characterization of the mec element types based on the structural features that were shown to be typical of mec elements carried by several MRSA clones. The strategy was validated by using a representative collection of pandemic MRSA clones in which the full structure of the associated mec elements was previously determined by hybridization and PCR screenings and also by DNA sequencing. The method was tested together with multilocus sequence typing and other typing methods for the characterization of 18 isolates representative of the MRSA clones recovered during a hospital outbreak in Barcelona, Spain. The multiplex PCR was shown to be rapid, robust, and capable in a single assay of identifying five structural types of the mec element among these strains, three major and two minor variants, each one of which has been already been seen among MRSA characterized earlier. This technique should be a useful addition to the armamentarium of molecular typing tools for the characterization of MRSA clonal types and for the rapid tentative identification of structural variants of the mec element.
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Idrees, Muhammad Mubashar, Khadija Saeed, Muhammad Akbar Shahid, Muhammad Akhtar, Khadija Qammar, Javariya Hassan, Tayyaba Khaliq, and Ali Saeed. "Prevalence of mecA- and mecC-Associated Methicillin-Resistant Staphylococcus aureus in Clinical Specimens, Punjab, Pakistan." Biomedicines 11, no. 3 (March 13, 2023): 878. http://dx.doi.org/10.3390/biomedicines11030878.
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Methicillin-resistant Staphylococcus aureus (MRSA) is a clinically prevalent bacterium and is resistant to many drugs. Genetic factors such as mec genes are considered to be responsible for this resistance. Recently, Staphylococcal Cassette Chromosome mec (SCCmec) element mutations produced mecC, a new genetic variant that encodes a transpeptidase enzyme (63% similarity with mecA-encoded PBP2a). This cross-sectional study was conducted to establish the prevalence of the mecA and mecC genes among phenotypically identified MRSA and their effectiveness against different antibiotics in clinical specimens. The prevalence of Staphylococcus aureus was 10.2% (n = 102) in the total number of clinical specimens collected (n = 1000). However, the prevalence of MRSA was 6.3% (n = 63) of the total samples collected, while it was 61.8% among total Staphylococcus aureus isolates. mec genes were confirmed in 96.8% (n = 61) isolates of MRSA, while 3.2% (n = 2) were found to be negative for mec genes. The combination of mecA and mecC was detected in 57.1% (n = 36) of the MRSA isolates. The prevalence of lone mecA was 31.8% (n = 20) and that of lone mecC was 7.9% (n = 5) among all the MRSA samples. Penicillin and amoxicillin/clavulanic acid were the most resistant antibiotics followed by norfloxacin (91.2%), levofloxacin (87.1%), ciprofloxacin (83.9%), azithromycin (78.6%), erythromycin (77.4%), moxifloxacin (69.8%), and sulfamethoxazole/trimethoprim (54.9%). On the other hand, vancomycin and teicoplanin (98.4%) were more effective drugs against MRSA followed by linezolid (96.7%), clindamycin (84.6%), chloramphenicol (83.7%), fusidic acid (70.6%), gentamicin (67.7%), and tetracycline (56.8%). In conclusion, a significant prevalence of mecA and mecC has been found among MRSA isolated from clinical specimens, which is likely responsible for antibiotic resistance in MRSA in our clinical settings. However, vancomycin, teicoplanin, and linezolid were found the top three most effective drugs against MRSA in our clinical settings. Thus, MRSA endemics in local areas require routine molecular and epidemiological investigation.
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Sabat, Artur J., Erik Bathoorn, Karsten Becker, Viktoria Akkerboom, Madalina Miskoski, Tim Durfee, and Alexander W. Friedrich. "Staphylococcal cassette chromosome mec containing a novel mec gene complex, B4." Journal of Antimicrobial Chemotherapy 76, no. 8 (May 15, 2021): 1986–90. http://dx.doi.org/10.1093/jac/dkab154.
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Abstract Objectives To describe a new subclass of mec class B complex identified in Staphylococcus epidermidis. Methods Four S. epidermidis isolates obtained from bloodstream infections in patients at University Medical Center Groningen (UMCG) were analysed by phenotypic antibiotic susceptibility testing and WGS. Results Sequence analysis revealed a new staphylococcal cassette chromosome mec (SCCmec) structure in isolate UMCG335. In this structure, plasmid pUB110 was found to be integrated into SCCmec IVc, creating a new SCCmec subtype, IVUMCG335. SCCmec IVc and a copy of plasmid pUB110 were found in other isolates, UMCG364 and UMCG341, respectively, indicating a probability that SCCmec IVUMCG335 could have evolved at the UMCG. SCCmec of UMCG337 contained a new genetic organization of the mec complex (IS431-ΔmecR1-mecA-IS431-pUB110-IS431-ψIS1272) that we have named B4. This new subclass of mec class B complex originated by IS431-mediated inversion of the DNA segment encompassing the plasmid and most of the genes of the mec complex with the exception of IS1272. As the SCCmec organization in UMCG337 differed by the inversion of an ∼10 kb sequence compared with SCCmec IVUMCG335, we have named it SCCmec subtype IVUMCG337. Isolates UMCG335 and UMCG337 carrying SCCmec IVUMCG335 and IVUMCG337, respectively, were associated with a restriction-modification system and a CRISPR-Cas system, creating a composite island of almost 70 kb. Conclusions Our findings highlight the importance of IS431 in the evolution of the SCCmec region. The increasing genetic diversity identified in the SCCmec elements imposes a great challenge for SCCmec typing methods and highlights possible difficulties with the SCCmec nomenclature.
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Hanssen, Anne-Merethe, and Johanna U. Ericson Sollid. "Multiple Staphylococcal Cassette Chromosomes and Allelic Variants of Cassette Chromosome Recombinases in Staphylococcus aureus and Coagulase-Negative Staphylococci from Norway." Antimicrobial Agents and Chemotherapy 51, no. 5 (February 16, 2007): 1671–77. http://dx.doi.org/10.1128/aac.00978-06.
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ABSTRACT We investigated the nature of the staphylococcal cassette chromosome mec (SCCmec) elements and cognate insertion sites in a collection of 42 clinical staphylococcal isolates of various species from Norway. The ccr and mec genes and the attachment sites (attL/attR) were identified by PCR, Southern blot hybridization, and DNA sequencing. We found 10 possibly new SCCmec types and one previously unreported variant of SCCmec type III (mec complex A, ccrAB3, and ccrC7) in Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis. Eleven of 42 strains contained multiple copies of ccr, suggesting the presence of mosaic structures composed of multiple SCC elements. S. haemolyticus contained ccrAB2 genes identical to those in S. aureus SCCmec type IV but lacked IS1272 and mec regulators. Two new allelic ccr variants, ccrC6 and ccrC7, were identified. Also, the presumed functional version of ccrB1 was found in a mecA-positive S. hominis strain and in mecA-negative S. epidermidis and S. hominis strains. Only minor differences in direct repeats in the left and right boundaries (attR/attL) were observed, while there was more variation in the inverted repeats. Coagulase-negative staphylococci (CoNS) contained several representatives of different ccr complexes and thus seemed to harbor multiple or composite new types of SCCmec. The enormous diversity observed in the SCCmec elements implies a large SCCmec reservoir in CoNS.
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Tsubakishita, Sae, Kyoko Kuwahara-Arai, Tadashi Baba, and Keiichi Hiramatsu. "Staphylococcal Cassette Chromosome mec-Like Element in Macrococcus caseolyticus." Antimicrobial Agents and Chemotherapy 54, no. 4 (January 19, 2010): 1469–75. http://dx.doi.org/10.1128/aac.00575-09.
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ABSTRACT Macrococcus is a bacterial genus that is closely related to Staphylococcus, which typically is isolated from animal skin and products. The genome analysis of multidrug-resistant Macrococcus caseolyticus strain JCSC5402, isolated from chicken, previously led to the identification of plasmid pMCCL2, which carries a transposon containing an unusual form of the Macrococcus mec gene complex (mecAm -mecR1m -mecIm -blaZm ). In M. caseolyticus strain JCSC7096, this mec transposon containing the mec gene complex (designated Tn6045 in this study) was found integrated downstream of orfX on the chromosome. Tn6045 of JCSC7096 was bracketed by the direct repeat sequences (DR) specifically recognized by cassette chromosome recombinase (CCR). A non-mecA-containing staphylococcal cassette chromosome (SCC) element, designated SCC7096, was integrated next to the mec transposon and separated from the latter by a DR. Nested PCR experiments showed that the mec transposon not only was excised singly but also coexcised with SCC7096 from the chromosome at the DRs. The coexcised elements formed the extrachromosomal closed circular DNA of the SCCmec-like element. SCCmec is known to be the mobile element conveying methicillin (meticillin) resistance in staphylococci. However, its origin has been unknown. Our observation revealed a potential mechanism of the generation of a new SCCmec-like element in M. caseolyticus, a commensal bacterium of food animals.
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Zarzyńska, Joanna, Małgorzata Gajewska, and Tomasz Motyl. "Effects of hormones and growth factors on TGF-β1 expression in bovine mammary epithelial cells." Journal of Dairy Research 72, no. 1 (January 14, 2005): 39–48. http://dx.doi.org/10.1017/s0022029904000639.
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The decline of mammary epithelial cell (MEC) number during mammary gland involution in the cow is due to inhibition of proliferation and induction of apoptosis. Transforming growth factor-beta 1 (TGF-β1) belongs to a group of intramammary auto/paracrine inhibitors of bovine MEC growth and inducers of apoptosis. However, the mechanism responsible for the regulation of TGF-β1 expression in MEC is not known. The present study examined the effect of the hormones, growth hormone (GH), somatostatin (STS), 17-β oestradiol (E2), progesterone (P4), as well as the growth factors, insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF), on TGF-β1 expression in the bovine MEC lines, BME-UV1 and MAC-T. The model of apoptosis in bovine mammary gland in vitro was applied by reduction of fetal bovine serum (FBS) (from 10% to 2% or 0·5% FBS) in the cell environment to show the relationship between TGF-β1 expression and apoptosis in bovine MEC. RT-PCR, Western blot and laser scanning cytometry (LSC) were used for analysis of TGF-β1 transcript and protein level as well as apoptosis and cell cycle in examined MEC. In this model of apoptosis, FBS deficiency (mimicking the naturally occurring decline in the access of bioactive compounds and nutrients at the end of lactation and dry period) was associated with increased TGF-β1 expression at the level of transcript and protein, induction of apoptosis and inhibition of cell cycle. Exogenous TGF-β1, IGF-I, EGF and GH inhibited FBS-deficiency-stimulated TGF-β1 expression. The suppressive effect of GH was reversed when cells were maintained longer in FBS-deficient medium. In general, STS, E2 and P4 increased TGF-β1 expression. However, this effect was dependent on hormone concentration and cell line. BME-UV1 cells were much more responsive to the peptides, GH, STS, IGF-I and EGF, whereas MAC-T cells were more responsive to the steroid sex hormones: E2 and P4.
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Chen, Yushu, Shashank Bharill, Zeynep Altun, Robert O’Hagan, Brian Coblitz, Ehud Y. Isacoff, and Martin Chalfie. "Caenorhabditis elegans paraoxonase-like proteins control the functional expression of DEG/ENaC mechanosensory proteins." Molecular Biology of the Cell 27, no. 8 (April 15, 2016): 1272–85. http://dx.doi.org/10.1091/mbc.e15-08-0561.
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Caenorhabditis elegans senses gentle touch via a mechanotransduction channel formed from the DEG/ENaC proteins MEC-4 and MEC-10. An additional protein, the paraoxonase-like protein MEC-6, is essential for transduction, and previous work suggested that MEC-6 was part of the transduction complex. We found that MEC-6 and a similar protein, POML-1, reside primarily in the endoplasmic reticulum and do not colocalize with MEC-4 on the plasma membrane in vivo. As with MEC-6, POML-1 is needed for touch sensitivity, the neurodegeneration caused by the mec-4(d) mutation, and the expression and distribution of MEC-4 in vivo. Both proteins are likely needed for the proper folding or assembly of MEC-4 channels in vivo as measured by FRET. MEC-6 detectably increases the rate of MEC-4 accumulation on the Xenopus oocyte plasma membrane. These results suggest that MEC-6 and POML-1 interact with MEC-4 to facilitate expression and localization of MEC-4 on the cell surface. Thus MEC-6 and POML-1 act more like chaperones for MEC-4 than channel components.
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Rasheed, Zahid, Hongying Zhang, Syed Masroor Anwar, and Babar Zaman. "Homogeneously Mixed Memory Charts with Application in the Substrate Production Process." Mathematical Problems in Engineering 2021 (October 14, 2021): 1–15. http://dx.doi.org/10.1155/2021/2582210.
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The cumulative sum (CUSUM) and the exponentially weighted moving average (EWMA) charts are renowned classical memory charts used to monitor small and moderate shifts in the process(s). Mixed memory charts like mixed EWMA-CUSUM (MEC) and mixed CUSUM-EWMA (MCE) are the advanced forms of classical memory charts used to identify shifts quickly in process parameters (location and/or dispersion). Similarly, the homogeneously weighted moving average (HWMA) chart is used for improved process monitoring. It will be worthwhile to combine the HWMA chart features with the existing mixed memory (MCE and MEC) charts to enhance the effectiveness of the mixed memory charts. Therefore, we proposed new charts: mixed HWMA-homogeneously CUSUM (MHWHC) and mixed homogeneously CUSUM-HWMA (MHCHW) charts. The Monte Carlo simulations are used to evaluate the proposed charts’ effectiveness. The average run length (ARL) is utilized to compare the proposed MHWHC and MHCHW charts’ performance with existing charts such as classical CUSUM and EWMA, MEC, MCE, and HWMA charts. The comparison revealed that the proposed mixed charts are superior to the existing counterparts, specifically monitoring small and moderate shifts. Finally, a real-life application using the manufacturing process’s data set is also provided from a practical point of view.
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Chen, Yushu, Shashank Bharill, Ehud Y. Isacoff, and Martin Chalfie. "Subunit composition of a DEG/ENaC mechanosensory channel of Caenorhabditis elegans." Proceedings of the National Academy of Sciences 112, no. 37 (August 31, 2015): 11690–95. http://dx.doi.org/10.1073/pnas.1515968112.
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Caenorhabditis elegans senses gentle touch in the six touch receptor neurons (TRNs) using a mechanotransduction complex that contains the pore-forming degenerin/epithelial sodium channel (DEG/ENaC) proteins MEC-4 and MEC-10. Past work has suggested these proteins interact with the paraoxonase-like MEC-6 and the cholesterol-binding stomatin-like MEC-2 proteins. Using single molecule optical imaging in Xenopus oocytes, we found that MEC-4 forms homotrimers and MEC-4 and MEC-10 form 4:4:10 heterotrimers. MEC-6 and MEC-2 do not associate tightly with these trimers and do not influence trimer stoichiometry, indicating that they are not part of the core channel transduction complex. Consistent with the in vitro data, MEC-10, but not MEC-6, formed puncta in TRN neurites that colocalize with MEC-4 when MEC-4 is overexpressed in the TRNs.
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Ma, Xiao Xue, Teruyo Ito, Chuntima Tiensasitorn, Mantana Jamklang, Piriyaporn Chongtrakool, Susan Boyle-Vavra, Robert S. Daum, and Keiichi Hiramatsu. "Novel Type of Staphylococcal Cassette Chromosome mec Identified in Community-Acquired Methicillin-Resistant Staphylococcus aureus Strains." Antimicrobial Agents and Chemotherapy 46, no. 4 (April 2002): 1147–52. http://dx.doi.org/10.1128/aac.46.4.1147-1152.2002.
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ABSTRACT We identified a new type of staphylococcal cassette chromosome mec (SCCmec) from two community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains. The novel element, designated type IV SCCmec, had a unique combination of the class B mec gene complex and the type 2 ccr gene complex and was much smaller in size (21 to 24 kb) than previously identified SCCmec elements of hospital-acquired MRSA. Consistent with the strains' susceptibilities to various non-β-lactam antibiotics, the type IV SCCmec was devoid of any antibiotic resistance genes other than the mecA gene.
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Tinorua, Sarah, Cyrielle Denjean, Pierre Nabat, Véronique Pont, Mathilde Arnaud, Thierry Bourrianne, Maria Dias Alves, and Eric Gardrat. "A 2-year intercomparison of three methods for measuring black carbon concentration at a high-altitude research station in Europe." Atmospheric Measurement Techniques 17, no. 13 (July 3, 2024): 3897–915. http://dx.doi.org/10.5194/amt-17-3897-2024.
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Abstract. Black carbon (BC) is one of the most important climate forcers with severe health effects. Large uncertainties in radiative forcing estimation and health impact assessment arise from the fact that there is no standardized method to measure BC mass concentration. This study presents a 2-year comparison of three state-of-the-art BC measurement techniques at the high-altitude research station Pic du Midi (PDM) located in the French Pyrenees at an altitude of 2877 m above sea level. A recently upgraded Aethalometer AE33, a thermal-optical analyser Sunset and a single-particle soot photometer SP2 were deployed to measure simultaneously the mass concentration of equivalent black carbon (MeBC), elemental carbon (MEC) and refractory black carbon (MrBC), respectively. Significant deviations in the response of the instruments were observed. All techniques responded to seasonal variations in the atmospheric changes in BC levels and exhibited good correlation during the whole study period. This indicates that the different instruments quantified the same particle type despite the fact that they are based on different physical principles. However the slopes and correlation coefficients varied between instrument pairs. The largest biases were observed for the AE33 with MeBC values that were around 2 times greater than MrBC and MEC values. The principal reasons of such large discrepancy were explained by the mass absorption cross section (MAC) that was too low and C values recommended by the AE33 manufacturer and applied to the absorption coefficients measured by the AE33. In addition, the long-range transport of dust particles at PDM in spring caused significant increases in the bias between AE33 and SP2 by up to a factor 8. The Sunset MEC measurements agreed within around 17 % with the SP2 MrBC values. The largest overestimations of MEC were observed when the total carbon concentrations were below 25 µg C cm−2, which is probably linked to the incorrect determination of the organic carbon (OC)–EC split point. Another cause of the discrepancy between instruments was found to be the limited detection range of the SP2, which did not allow for the total detection of fine rBC particles. The procedure used to estimate the missing mass fraction of rBC not covered by the measurement range of the SP2 was found to be critical. We found that a time-dependent correction based on fitting the observed rBC size distribution with a multimodal lognormal distribution is needed to accurately estimate MrBC over a larger size range.
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Wu, Jingyan, Jiawei Zhang, Yuming Xiao, and Yuefeng Ji. "Cooperative Offloading in D2D-Enabled Three-Tier MEC Networks for IoT." Wireless Communications and Mobile Computing 2021 (August 16, 2021): 1–13. http://dx.doi.org/10.1155/2021/9977700.
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Mobile/multi-access edge computing (MEC) takes advantage of its proximity to end-users, which greatly reduces the transmission delay of task offloading compared to mobile cloud computing (MCC). Offloading computing tasks to edge servers with a certain amount of computing ability can also reduce the computing delay. Meanwhile, device-to-device (D2D) cooperation can help to process small-scale delay-sensitive tasks to further decrease the delay of tasks. But where to offload the computing tasks is a critical issue. In this article, we integrate MEC and D2D cooperation techniques to optimize the offloading decisions and resource allocation problem in D2D-enabled three-tier MEC networks for Internet of Things (IoT). Mobile devices (MDs), edge clouds, and central cloud data center (DC) make up these three-tier MEC networks. They cooperate with each other to finish the offloading tasks. Each task can be processed by MD itself or its neighboring MDs at device tier, by edge servers at edge tier, or by remote cloud servers at cloud tier. Under the maximum energy cost constraints, we formulate the cooperative offloading problem into a mixed-integer nonlinear problem aiming to minimize the total delay of tasks. We utilize the alternating direction method of multipliers (ADMM) to speed up the computing process. The proposed scheme decomposes the complicated problem into 3 smaller subproblems, which are solved in a parallel fashion. Finally, we compare our proposal with D2D and MEC networks in simulations. Numerical results validate that the proposed D2D-enabled MEC networks for IoT can significantly enhance the computing abilities and reduce the total delay of tasks.
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Carton, Geoffrey, Carter DuVal, and Arthur Trembanis. "A Risk Framework for Munitions and Explosives of Concern in Support of U.S. Offshore Wind Energy Development." Marine Technology Society Journal 53, no. 2 (March 1, 2019): 6–20. http://dx.doi.org/10.4031/mtsj.53.2.1.
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AbstractMunitions and explosives of concern (MEC) in U.S. waters can present a risk to the development and operation of offshore wind energy resources. Therefore, the U.S. Bureau of Ocean Energy Management requires offshore wind energy developers to evaluate the risk MEC poses to the development, operation, and maintenance of offshore wind energy generation and transmission systems. This article describes an MEC risk management framework consisting of the following steps: (1) MEC hazard assessment, (2) MEC risk assessment, (3) MEC risk validation, and (4) MEC risk mitigation. The MEC hazard assessment involves historical research to identify MEC potentially present in the development area. The MEC risk assessment evaluates the development activities and provides a relative MEC risk ranking for those activities. The developer determines the acceptability of these risks, and any potentially unacceptable MEC risks undergo risk validation through field surveys. The developer then considers the tolerability of the validated risks and develops and implements an appropriate MEC risk mitigation strategy based on actual site conditions. A risk framework provides a structured method to plan and operationalize the identification, evaluation, and mitigation of MEC risk throughout the development, operation, and maintenance life cycle of an offshore wind energy generation and transmission project.
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Ito, T., Y. Katayama, and K. Hiramatsu. "Cloning and Nucleotide Sequence Determination of the Entire mec DNA of Pre-Methicillin-Resistant Staphylococcus aureus N315." Antimicrobial Agents and Chemotherapy 43, no. 6 (June 1, 1999): 1449–58. http://dx.doi.org/10.1128/aac.43.6.1449.
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ABSTRACT In methicillin-resistant Staphylococcus aureus, the methicillin resistance gene mecA is localized within a large chromosomal region which is absent in the methicillin-susceptibleS. aureus chromosome. The region, designatedmec DNA, is speculated to have originated from the genome of another bacterial species and become integrated into the chromosome of the S. aureus cell in the past. We report here cloning and determination of the structure of the entire mec DNA sequence from a Japanese S. aureus strain, N315. Themec DNA was found to be 51,669 bp long, including terminal inverted repeats of 27 bp and a characteristic pair of direct repeat sequences of 15 bp each: one is situated in the right extremity ofmec DNA, and the other is situated outside themec DNA and abuts the left boundary of mec DNA. The integration site of mec DNA was found to be located in an open reading frame (ORF) of unknown function, designatedorfX. Clusters of antibiotic resistance genes were noted inmec DNA carried by transposon Tn554 and an integrated copy of plasmid pUB110. Both the transposon and plasmid were integrated in the proximity of the mecA gene, the latter being flanked by a pair of insertion sequence IS431elements. Many ORFs other than those encoding antibiotic resistance were considered nonfunctional because of the acquired mutations or partial deletions found in the ORFs. Two ORFs potentially encoding novel site-specific recombinases were found in mec DNA. However, there was no ORF that might encode mecDNA-specific transposase or integrase proteins, indicating that themec DNA is not a transposon or a bacteriophage in nature.
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Brown, Austin L., Zhiwen Liao, and Miriam B. Goodman. "MEC-2 and MEC-6 in the Caenorhabditis elegans Sensory Mechanotransduction Complex: Auxiliary Subunits that Enable Channel Activity." Journal of General Physiology 131, no. 6 (May 26, 2008): 605–16. http://dx.doi.org/10.1085/jgp.200709910.
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The ion channel formed by the homologous proteins MEC-4 and MEC-10 forms the core of a sensory mechanotransduction channel in Caenorhabditis elegans. Although the products of other mec genes are key players in the biophysics of transduction, the mechanism by which they contribute to the properties of the channel is unknown. Here, we investigate the role of two auxiliary channel subunits, MEC-2 (stomatin-like) and MEC-6 (paraoxonase-like), by coexpressing them with constitutively active MEC-4/MEC-10 heteromeric channels in Xenopus oocytes. This work extends prior work demonstrating that MEC-2 and MEC-6 synergistically increase macroscopic current. We use single-channel recordings and biochemistry to show that these auxiliary subunits alter function by increasing the number of channels in an active state rather than by dramatically affecting either single-channel properties or surface expression. We also use two-electrode voltage clamp and outside-out macropatch recording to examine the effects of divalent cations and proteases, known regulators of channel family members. Finally, we examine the role of cholesterol binding in the mechanism of MEC-2 action by measuring whole-cell and single-channel currents in MEC-2 mutants deficient in cholesterol binding. We suggest that MEC-2 and MEC-6 play essential roles in modulating both the local membrane environment of MEC-4/MEC-10 channels and the availability of such channels to be gated by force in vivo.
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Fukushige, T., Z. K. Siddiqui, M. Chou, J. G. Culotti, C. B. Gogonea, S. S. Siddiqui, and M. Hamelin. "MEC-12, an alpha-tubulin required for touch sensitivity in C. elegans." Journal of Cell Science 112, no. 3 (February 1, 1999): 395–403. http://dx.doi.org/10.1242/jcs.112.3.395.
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mec-12 is one of a dozen genes required for touch receptor neuron function in Caenorhabditis elegans. Some mec-12 mutants (mechanosensory-defective) lack the large-diameter microtubules that are characteristic of these neurons (15 protofilaments, as opposed to 11). Mutants of mec-7, a alpha-tubulin encoding gene, have a similar phenotype. We have identified the nature of mec-12 by germline transformation rescue and characterization of a point mutation. Sequence analysis of the mec-12 encoded product (MEC-12) indicates that it corresponds to a novel C. elegans alpha-tubulin. MEC-12 is the only identified C. elegans alpha-tubulin that contains a lysine at position 40, a known site of post-translational acetylation. Some mec-12 mutations eliminate microtubule acetylation as assayed immunocyto-chemically; phenotypic rescue using a MEC-12 variant lacking the lysine-40 showed that acetylation is not required for MEC-12 activity. Although functionally needed only in the touch neurons, mec-12 is expressed in several other neuron types. These results support the notion that tubulin isotype diversity contributes to the formation of distinct classes of microtubules; 15-protofilament microtubule assembly requires MEC-12 alpha-tubulin and MEC-7 beta-tubulin, which are both highly expressed in the touch receptor neurons. MEC-12 is the first reported alpha-tubulin isotype that appears to be required in a single class of neuronal microtubules.
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Safo, Martin K., Qixun Zhao, Tzu-Ping Ko, Faik N. Musayev, Howard Robinson, Neel Scarsdale, Andrew H. J. Wang, and Gordon L. Archer. "Crystal Structures of the BlaI Repressor from Staphylococcus aureus and Its Complex with DNA: Insights into Transcriptional Regulation of the bla and mec Operons." Journal of Bacteriology 187, no. 5 (March 1, 2005): 1833–44. http://dx.doi.org/10.1128/jb.187.5.1833-1844.2005.
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ABSTRACT The 14-kDa BlaI protein represses the transcription of blaZ, the gene encoding β-lactamase. It is homologous to MecI, which regulates the expression of mecA, the gene encoding the penicillin binding protein PBP2a. These genes mediate resistance to β-lactam antibiotics in staphylococci. Both repressors can bind either bla or mec DNA promoter-operator sequences. Regulated resistance genes are activated via receptor-mediated cleavage of the repressors. Cleavage is induced when β-lactam antibiotics bind the extramembrane sensor of the sensor-transducer signaling molecules, BlaR1 or MecR1. The crystal structures of BlaI from Staphylococcus aureus, both in free form and in complex with 32 bp of DNA of the mec operator, have been determined to 2.0- and 2.7-Å resolutions, respectively. The structure of MecI, also in free form and in complex with the bla operator, has been previously reported. Both repressors form homodimers, with each monomer composed of an N-terminal DNA binding domain of winged helix-turn-helix topology and a C-terminal dimerization domain. The structure of BlaI in complex with the mec operator shows a protein-DNA interface that is conserved between both mec and bla targets. The recognition helix α3 interacts specifically with the conserved TACA/TGTA DNA binding motif. BlaI and, probably, MecI dimers bind to opposite faces of the mec DNA double helix in an up-and-down arrangement, whereas MecI and, probably, BlaI dimers bind to the same DNA face of bla promoter-operator DNA. This is due to the different spacing of mec and bla DNA binding sites. Furthermore, the flexibility of the dimeric proteins may make the C-terminal proteolytic cleavage site more accessible when the repressors are bound to DNA than when they are in solution, suggesting that the induction cascade involves bound rather than free repressor.
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Barnetova, I., I. Vackova, and P. Firla. " Dynamics of epigenetic remodeling in interspecies porcine zygotes." Czech Journal of Animal Science 57, No. 2 (February 21, 2012): 83–94. http://dx.doi.org/10.17221/5135-cjas.
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The process of active paternal chromatin demethylation after fertilization in the pig is not fully understood and very inconsistent data have been published by different research groups. We have applied the interspecies intracytoplasmic sperm injection (iICSI) to evaluate remodeling capabilities of porcine oocytes in more details. We injected mouse frozen-thawed sperm heads into porcine in vitro matured or ovulated oocytes, respectively. Embryos produced by intracytoplasmic sperm injection (ICSI) of boar spermatozoa into porcine ovulated oocytes (intraspecies) served as controls. Zygotes with 2-pronuclei were labeled with antibodies against certain epigenetic modifications (5-methylcytosine, 5-MeC; heterochromatin protein 1, HP1; trimethylation of H3/K4, H3/K4-me3; and dimethylation of H3/K9, H3/K9-me2). The labeling patterns were not different between zygotes produced from in vitro matured and ovulated oocytes. Both pronuclei were symmetrically labeled with 5-MeC, HP1, and H3/K4-me3 antibodies. Asymmetrical labeling was observed only with H3/K9-me2 antibody. The labeling of interspecies zygotes was similar to that of intraspecies zygotes. Moreover, the DNA demethylation was observed neither in control zygotes (intraspecies). The only difference observed between zygotes produced from in vitro matured and ovulated oocytes was in their ability to be activated. Intraspecies zygotes produced from ovulated oocytes were able to form the paternal pronucleus without additional activation; the zygotes produced from in vitro matured oocytes formed the paternal pronucleus only after additional activation with electric pulses. Our results show that the remodeling abilities of in vitro matured and ovulated oocytes are essentially similar. Moreover, it seems that reasons of inconsistent data reporting the active demethylation in the pig are more complicated and they are not associated exclusively with the oocyte quality.
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Maray, Mohammed, and Junaid Shuja. "Computation Offloading in Mobile Cloud Computing and Mobile Edge Computing: Survey, Taxonomy, and Open Issues." Mobile Information Systems 2022 (June 28, 2022): 1–17. http://dx.doi.org/10.1155/2022/1121822.
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Cloud and mobile edge computing (MEC) provides a wide range of computing services for mobile applications. In particular, mobile edge computing enables a computing and storage infrastructure provisioned closely to the end-users at the edge of a cellular network. The small base stations are deployed to establish a mobile edge network that can be coined with cloud infrastructure. A large number of enterprises and individuals rely on services offered by mobile edge and clouds to meet their computational and storage demands. Based on user behavior and demand, the computational tasks are first offloaded from mobile users to the mobile edge network and then executed at one or several specific base stations in the mobile edge network. The MEC architecture has the capability to handle a large number of devices that in turn generate high volumes of traffic. In this work, we first provide a holistic overview of MCC/MEC technology that includes the background and evolution of remote computation technologies. Then, the main part of this paper surveys up-to-date research on the concepts of offloading mechanisms, offloading granularities, and computational offloading techniques. Furthermore, we discuss the offloading mechanism in the static and dynamic environment along with optimization techniques. We further discuss the challenges and potential future directions for MEC research.
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Khalele, Bacem, Juan B. Laforga, Karol Kajo, and Katarína Kajová Macháleková. "Adenosquamous Carcinomas and Mucinous Adenocarcinoma of the Minor Salivary Glands: Immunohistochemical and Molecular Insights." Journal of Molecular Pathology 3, no. 4 (November 3, 2022): 273–85. http://dx.doi.org/10.3390/jmp3040023.
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There is confusion about the diagnosis, histogenesis and taxonomical efforts regarding adenosquamous carcinomas (ASCs) and mucinous adenocarcinomas (MACs), especially with calls for reconsidering the nature of high-grade mucoepidermoid carcinoma (MEC). This study aims to compare the genetic profiles of ASCs and MACs that have been previously reported in the literature and investigate if either ASC or MAC is closer in genetic mutations to high-grade MEC. Systematic searches in the NCBI, Web of Science, and Scopus databases were performed between January 2000 and August 2022. The retrieved genetic mutations were processed and annotated. Protein–protein network analysis was conducted for each neoplasm. The results were viewed and discussed in terms of molecular oncogenesis of ASCs and MACs at different topographies. Molecular profile mapping was conducted by annotating all the retrieved genes for each neoplasm using genetic network analysis (Cystoscape software program). The genetic profile of each lesion was compared to that of high-grade MEC. To conclude, both genetic profiles do not tend to intersect specifically with high-grade MEC, except for the generic mutations commonly detected in all high-grade head and neck tumors. However, the availability of data on the molecular profile of each lesion limits the generalizability of the findings of this study.
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Lee, Myoung Eun, Yongtae Ahn, Seung Gu Shin, and Jae Woo Chung. "Enhancement of Biogas Production in Anaerobic Digestion Using Microbial Electrolysis Cell Seed Sludge." Energies 15, no. 19 (September 25, 2022): 7042. http://dx.doi.org/10.3390/en15197042.
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Anaerobic digestion (AD) can produce renewable energy and reduce carbon emissions, but the energy conversion efficiency is still limited in some waste streams. This study tested the effect of applied voltage removal for microbial electrolysis cells (MECs) treating primary sewage sludge. Two MECs were operated in parallel: a MEC-0.3 V with an applied voltage of 0.3 V and a MEC-OCV with open circuit voltage. Both reactors were inoculated with seed sludge originating from a MEC at 0.3 V applied voltage, and three batch cycles were operated for 36 d. The methane production of the MEC-OCV was 3759 mL/L in the first cycle and 2759 mL/L in the second cycle, which was similar (105% and 103%, respectively) to that of the MEC-0.3 V. However, in the third cycle, the methane production of the MEC-OCV (1762 mL/L) was 38.8% lower than that of the MEC-0.3 V (4545 mL/L). The methane contents in the biogas were 68.6–74.2% from the MEC-OCV, comparable to those from the MEC-0.3 V (66.6–71.1%). These results indicate that not only the MEC-0.3V but also the MEC-OCV outperformed AD in terms of methane yield and productivity, and the promotion using MEC-derived inoculum persisted equally with the MEC-OCV for two batch cycles after removing the applied voltage. Therefore, a MEC operation with cycled power supply may be beneficial in reducing the electric energy usage and improving the biogas production performance, compared to conventional AD.
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Білявина, Н. М., В. З. Туркевич, А. М. Курилюк, Д. А. Стратійчук, О. І. Наконечна, П. П. Когутюк, and Л. П. Стасюк. "Вплив спікання в умовах високих температур і тиску та механохімічного синтезу на кристалічну структуру монокарбідів TiC, ZrC, HfC." Reports of the National Academy of Sciences of Ukraine, no. 3 (July 11, 2023): 40–48. http://dx.doi.org/10.15407/dopovidi2023.03.040.
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Методом рентгенівської дифракції вивчено фазовий склад продуктів HPHT спікання (7,7 ГПа, 1600—2450 °С) систем cBN—TiC—Al, cBN—ZrC—Al та cBN—HfC—Al (об’ємне співвідношення компонентів шихти 60 : 35 : 5). Встановлено, що твердофазні реакції в цих системах ініціюються за температур баротермічної обробки, вищих за 2000 °С, і спричинюють утворення боридів відповідного металу (MeB2) та AlN. На основі рентгеноструктурних розрахунків кристалічної структури окремих фазових складових показано, що за високих температур HPHT спікання бориди MeB2 розчиняють невелику кількість алюмінію, а вихідні монокарбіди MeC перетворюються в карбіди MeCʹ, які в дійсності являють собою тверді розчини Me1–xAlxC, що містять до ≈8, ≈7 та ≈6 ат. % Al для TiC, ZrC та HfC відповідно. Механізм накопичення алюмінію в металевій підґратці твердих розчинів Me1–xAlxC здійснюється через попереднє утворення в структурах вихідних карбідів MeC вакансій, кількість яких корелює зі значенням ентальпії утворення цих карбідів.
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Dorosko, Stephanie M., and Ruth I. Connor. "Primary Human Mammary Epithelial Cells Endocytose HIV-1 and Facilitate Viral Infection of CD4+ T Lymphocytes." Journal of Virology 84, no. 20 (August 11, 2010): 10533–42. http://dx.doi.org/10.1128/jvi.01263-10.
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ABSTRACT The contribution of mammary epithelial cells (MEC) to human immunodeficiency virus type 1 (HIV-1) in breast milk remains largely unknown. While breast milk contains CD4+ cells throughout the breast-feeding period, it is not known whether MEC directly support HIV-1 infection or facilitate infection of CD4+ cells in the breast compartment. This study evaluated primary human MEC for direct infection with HIV-1 and for indirect transfer of infection to CD4+ target cells. Primary human MEC were isolated and assessed for expression of HIV-1 receptors. MEC were exposed to CCR5-, CXCR4- and dual-tropic strains of HIV-1 and evaluated for viral reverse transcription and integration and productive viral infection. MEC were also tested for the ability to transfer HIV to CD4+ target cells and to activate resting CD4+ T cells. Our results demonstrate that MEC express HIV-1 receptor proteins CD4, CCR5, CXCR4, and galactosyl ceramide (GalCer). While no evidence for direct infection of MEC was found, HIV-1 virions were observed in MEC endosomal compartments. Coculture of HIV-exposed MEC resulted in productive infection of activated CD4+ T cells. In addition, MEC secretions increased HIV-1 replication and proliferation of infected target cells. Overall, our results indicate that MEC are capable of endosomal uptake of HIV-1 and can facilitate virus infection and replication in CD4+ target cells. These findings suggest that MEC may serve as a viral reservoir for HIV-1 and may enhance infection of CD4+ T lymphocytes in vivo.
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Hassanein, Amro, Freddy Witarsa, Stephanie Lansing, Ling Qiu, and Yong Liang. "Bio-Electrochemical Enhancement of Hydrogen and Methane Production in a Combined Anaerobic Digester (AD) and Microbial Electrolysis Cell (MEC) from Dairy Manure." Sustainability 12, no. 20 (October 14, 2020): 8491. http://dx.doi.org/10.3390/su12208491.
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Anaerobic digestion (AD) is a biological-based technology that generates methane-enriched biogas. A microbial electrolysis cell (MEC) uses electricity to initiate bacterial oxidization of organic matter to produce hydrogen. This study determined the effect of energy production and waste treatment when using dairy manure in a combined AD and MEC (AD-MEC) system compared to AD without MEC (AD-only). In the AD-MEC system, a single chamber MEC (150 mL) was placed inside a 10 L digester on day 20 of the digestion process and run for 272 h (11 days) to determine residual treatment and energy capacity with an MEC included. Cumulative H2 and CH4 production in the AD-MEC (2.43 L H2 and 23.6 L CH4) was higher than AD-only (0.00 L H2 and 10.9 L CH4). Hydrogen concentration during the first 24 h of MEC introduction constituted 20% of the produced biogas, after which time the H2 decreased as the CH4 concentration increased from 50% to 63%. The efficiency of electrical energy recovery (ηE) in the MEC was 73% (ηE min.) to 324% (ηE max.), with an average increase of 170% in total energy compared to AD-only. Chemical oxygen demand (COD) removal was higher in the AD-MEC (7.09 kJ/g COD removed) system compared to AD-only (6.19 kJ/g COD removed). This study showed that adding an MEC during the digestion process could increase overall energy production and organic removal from dairy manure.
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Duggan, A., C. Ma, and M. Chalfie. "Regulation of touch receptor differentiation by the Caenorhabditis elegans mec-3 and unc-86 genes." Development 125, no. 20 (October 15, 1998): 4107–19. http://dx.doi.org/10.1242/dev.125.20.4107.
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The nematode Caenorhabditis elegans possesses six morphologically similar neurons that are responsible for sensing gentle touch to the body. Previous genetic studies identified genes that are necessary for the production and differentiation of these touch cells. In particular, unc-86 encodes a POU-type homeodomain protein needed for the production of the touch cells, while mec-3 encodes a LIM-type homeodomain protein needed for the differentiation of the touch cells. Molecular studies showed that MEC-3 and UNC-86 bind cooperatively to sites in the mec-3 promoter and can synergistically activate transcription from it in vitro. Here we show that UNC-86::MEC-3 hetero-oligomer-binding sites are also found in the promoters of two presumed targets of mec-3, the mec-4 and mec-7 genes, that are necessary for the function of the touch cells. These sites, which are well-conserved in the related nematode C. briggsae, are required for promoter activity. When one of the binding sites is cloned into a heterologous promoter, expression is found in the touch cells and two to four other cells that express mec-3 and unc-86. These data support a model in which touch-cell differentiation is specified, in part, by the UNC-86::MEC-3 hetero-oligomer and not by MEC-3 alone. Ectopic expression of mec-3, driven by a heat-shock promoter, also supports this hypothesis: the acquisition of touch-cell characteristics by several additional cells under these conditions required unc-86. Since the touch-cell lineages express UNC-86 before MEC-3, MEC-3 appears to modify the activity of UNC-86, leading to touch-cell-specific gene expression. Because both UNC-86 and MEC-3 have activation domains, the formation of the hetero-oligomer may create a strong activator. In the modification of UNC-86 function by MEC-3 in the touch cells, these studies provide an example of how the sequential activation of transcription factors can determine cell fate within particular cell lineages.
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Matthewman, Cristina, Christina K. Johnson, David M. Miller, and Laura Bianchi. "Functional features of the “finger” domain of the DEG/ENaC channels MEC-4 and UNC-8." American Journal of Physiology-Cell Physiology 315, no. 2 (August 1, 2018): C155—C163. http://dx.doi.org/10.1152/ajpcell.00297.2017.
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UNC-8 and MEC-4 are two members of the degenerin/epithelial Na+ channel (DEG/ENaC) family of voltage-independent Na+ channels that share a high degree of sequence homology and functional similarity. For example, both can be hyperactivated by genetic mutations [UNC-8(d) and MEC-4(d)] that induce neuronal death by necrosis. Both depend in vivo on chaperone protein MEC-6 for function, as demonstrated by the finding that neuronal death induced by hyperactive UNC-8 and MEC-4 channels is prevented by null mutations in mec-6. UNC-8 and MEC-4 differ functionally in three major ways: 1) MEC-4 is calcium permeable, whereas UNC-8 is not; 2) UNC-8, but not MEC-4, is blocked by extracellular calcium and magnesium in the micromolar range; and 3) MEC-6 increases the number of MEC-4 channels at the cell surface in oocytes but does not have this effect on UNC-8. We previously reported that Ca2+permeability of MEC-4 is conferred by the second transmembrane domain. We show here that the extracellular “finger” domain of UNC-8 is sufficient to mediate inhibition by divalent cations and that regulation by MEC-6 also depends on this region. Thus, our work confirms that the finger domain houses residues involved in gating of this channel class and shows for the first time that the finger domain also mediates regulation by chaperone protein MEC-6. Given that the finger domain is the most divergent region across the DEG/ENaC family, we speculate that it influences channel trafficking and function in a unique manner depending on the channel subunit.
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Sedhom, Germien G., Alshimaa H. Ismail, and Basma M. Yousef. "Literature Review and Novel Trends of Mobile Edge Computing for 5G and Beyond." Journal of Artificial Intelligence and Metaheuristics 2, no. 2 (2022): 18–28. http://dx.doi.org/10.54216/jaim.020202.
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Because of the rapid evolution of communications technologies, such as the Internet of Things (IoT) and fifth generation (5G) systems and beyond, the latest developments have seen a fundamental change in mobile computing. Mobile computing is moved from central mobile cloud computing to mobile edge computing (MEC). Therefore, MEC is considered an essential technology for 5G technology and beyond. The MEC technology permits user equipment (UEs) to execute numerous high-computational operations by creating computing capabilities at the edge networks and inside access networks. Consequently, in this paper, we extensively address the role of MEC in 5G networks and beyond. Accordingly, we first investigate the MEC architecture, the characteristics of edge computing, and the MEC challenges. Then, the paper discusses the MEC use cases and service scenarios. Further, computations offloading is explored. Lastly, we propose upcoming research difficulties in incorporating MEC with the 5G system and beyond.
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Lee, Donghwan, Jinwon Kim, Hwijin Seo, and Yongtae Ahn. "Effect of Ultrasonic Pretreatment of Sewage Sludge on the Performance of Bioelectrochemical Anaerobic Digester." Journal of Korean Society of Environmental Engineers 44, no. 1 (January 31, 2022): 13–20. http://dx.doi.org/10.4491/ksee.2022.44.1.13.
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Objectives : This study examined the effect of ultrasonic pretreatment on primary sewage sludge (raw sludge) solubilization and its subsequent microbial electrolysis cells (MECs) operation performance.Methods : To compare the effect of ultrasound on raw sludge solubilization, ultrasonic pretreatment was conducted at 1~4 W/mL energy density for 5~30 min. In MECs operation, raw sludge was used as a control group, and ultrasound pretreated sludge was used as an experimental group. For comparing MECs performance, biogas production, and organic matter removal were analyzed.Results and Discussion : The optimal experimental condition for ultrasonic pretreatment were 30 min of sonication time at 3 W/mL. In methane production, MEC with ultrasound pretreatment (MEC 3W) produced 243 mL/L more methane than that of unpretreated MEC (MEC) by 4,970 mL/L at 1, 3 cycles. In the modified Gompertz model analysis, the lag phase of MEC 3W was 0.46 days, which was 0.12 days longer than MEC. The maximum methane production rate of MEC 3W by 938.5 mL/L/day was also higher than MEC. MEC 3W showed a 1.8% higher TS removal rate, 2.4% VS removal rate than MEC. COD removal rate also improved by 2.0% when ultrasound pretreatment was applied. The methane yield of MEC with ultrasound pretreatment (377.4 mL/g VSin.) was 0.4% higher than that of MEC without pretreatment.Conclusion Ultrasonic pretreatment of sewage sludge improved the methane production and organic removal in microbial electrolysis cells. It is necessary to find the optimal operating conditions to obtain the maximize the performance.
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Shamanin, Vladimir A., and Elliot J. Androphy. "Immortalization of Human Mammary Epithelial Cells Is Associated with Inactivation of the p14ARF-p53 Pathway." Molecular and Cellular Biology 24, no. 5 (March 1, 2004): 2144–52. http://dx.doi.org/10.1128/mcb.24.5.2144-2152.2004.
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ABSTRACT Inactivation of the ARF-p53 tumor suppressor pathway leads to immortalization of murine fibroblasts. The role of this pathway in immortalization of human epithelial cells is not clear. We analyzed the functionality of the p14ARF-p53 pathway in human mammary epithelial cells (MEC) immortalized by human papillomavirus 16 (HPV16) E6, the p53 degradation-defective E6 mutant Y54D, or hTERT. E6-MEC or E6Y54D-MEC maintains high-level expression of p14ARF. Late-passage hTERT-immortalized MEC express p53 but down-regulate p14ARF. Enforced expression of p14ARF induces p53-dependent senescence in hTERT-MEC, while both E6-MEC and E6Y54D-MEC are resistant. We show that E6Y54D inhibits p14ARF-induced activation of p53 without inactivation of the p53-dependent DNA damage response. Hence, p53 degradation and inhibition of p14ARF signaling to p53 are independent functions of HPV16 E6. Our observations imply that long-term proliferation of MEC requires inactivation of the p14ARF-p53 pathway.
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Cui, Mengmeng, Yiming Fei, and Yin Liu. "A Survey on Secure Deployment of Mobile Services in Edge Computing." Security and Communication Networks 2021 (January 2, 2021): 1–8. http://dx.doi.org/10.1155/2021/8846239.
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Mobile edge computing (MEC) is an emerging technology that is recognized as a key to 5G networks. Because MEC provides an IT service environment and cloud-computing services at the edge of the mobile network, researchers hope to use MEC for secure service deployment, such as Internet of vehicles, Internet of Things (IoT), and autonomous vehicles. Because of the characteristics of MEC which do not have terminal servers, it tends to be deployed on the edge of networks. However, there are few related works that systematically introduce the deployment of MEC. Also, secure service deployment frameworks with MEC are even rare. For this reason, we have conducted a comprehensive and concrete survey of recent research studies on secure deployment. Although numerous research studies and experiments about MEC service deployment have been conducted, there are few systematic summaries that conclude basic concepts and development strategies about secure service deployment of commercial MEC. To make up for the gap, a detailed and complete survey about relative achievements is presented.
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Chatzigeorgiou, Marios, Laura Grundy, Katie S. Kindt, Wei-Hsiang Lee, Monica Driscoll, and William R. Schafer. "Spatial Asymmetry in the Mechanosensory Phenotypes of the C. elegans DEG/ENaC Gene mec-10." Journal of Neurophysiology 104, no. 6 (December 2010): 3334–44. http://dx.doi.org/10.1152/jn.00330.2010.
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DEG/ENaC channels have been broadly implicated in mechanosensory transduction, yet many questions remain about how these proteins contribute to complexes that sense mechanical stimuli. In C. elegans, two DEG/ENaC channel subunits are thought to contribute to a gentle touch transduction complex: MEC-4, which is essential for gentle touch sensation, and MEC-10, whose importance is less well defined. By characterizing a mec-10 deletion mutant, we have found that MEC-10 is important, but not essential, for gentle touch responses in the body touch neurons ALM, PLM, and PVM. Surprisingly, the requirement for MEC-10 in ALM and PLM is spatially asymmetric; mec-10 animals show significant behavioral and physiological responses to stimulation at the distal end of touch neuron dendrites, but respond poorly to stimuli applied near the neuronal cell body. The subcellular distribution of a rescuing MEC-10::GFP translational fusion was found to be restricted to the neuronal cell body and proximal dendrite, consistent with the hypothesis that MEC-10 protein is asymmetrically distributed within the touch neuron process. These results suggest that MEC-10 may contribute to only a subset of gentle touch mechanosensory complexes found preferentially at the proximal dendrite.
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Lai, C. C., K. Hong, M. Kinnell, M. Chalfie, and M. Driscoll. "Sequence and transmembrane topology of MEC-4, an ion channel subunit required for mechanotransduction in Caenorhabditis elegans." Journal of Cell Biology 133, no. 5 (June 1, 1996): 1071–81. http://dx.doi.org/10.1083/jcb.133.5.1071.
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The process by which mechanical stimuli are converted into cellular responses is poorly understood, in part because key molecules in this mode of signal transduction, the mechanically gated ion channels, have eluded cloning efforts. The Caenorhabditis elegans mec-4 gene encodes a subunit of a candidate mechanosensitive ion channel that plays a critical role in touch reception. Comparative sequence analysis of C. elegans and Caenorhabditis briggsae mec-4 genes was used to initiate molecular studies that establish MEC-4 as a 768-amino acid protein that includes two hydrophobic domains theoretically capable of spanning a lipid bilayer. Immunoprecipitation of in vitro translated mec-4 protein with domain-specific anti-MEC-4 antibodies and in vivo characterization of a series of mec-4lacZ fusion proteins both support the hypothesis that MEC-4 crosses the membrane twice. The MEC-4 amino- and carboxy-terminal domains are situated in the cytoplasm and a large domain, which includes three Cys-rich regions, is extracellular. Definition of transmembrane topology defines regions that might interact with the extracellular matrix or cytoskeleton to mediate mechanical signaling.
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Nishimura, Hiromi, Denan Jin, Ichita Kinoshita, Masataka Taniuchi, Masaaki Higashino, Tetsuya Terada, Shinji Takai, and Ryo Kawata. "Increased Chymase-Positive Mast Cells in High-Grade Mucoepidermoid Carcinoma of the Parotid Gland." International Journal of Molecular Sciences 24, no. 9 (May 5, 2023): 8267. http://dx.doi.org/10.3390/ijms24098267.
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It has long been known that high-grade mucoepidermoid carcinoma (MEC) has a poor prognosis, but the detailed molecular and biological mechanisms underlying this are not fully understood. In the present study, the pattern of chymase-positive mast cells, as well as chymase gene expression, in high-grade MEC was compared to that of low-grade and intermediate-grade MEC by using 44 resected tumor samples of MEC of the parotid gland. Chymase expression, as well as chymase-positive mast cells, was found to be markedly increased in high-grade MEC. Significant increases in PCNA-positive cells and VEGF gene expression, as well as lymphangiogenesis, were also confirmed in high-grade MEC. Chymase substrates, such as the latent transforming growth factor-beta (TGF-β) 1 and pro-matrix metalloproteinase (MMP)-9, were also detected immunohistologically in high-grade MEC. These findings suggested that the increased chymase activity may increase proliferative activity, as well as metastasis in the malignant condition, and the inhibition of chymase may be a strategy to improve the poor prognosis of high-grade MEC of the parotid gland.
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Koo, Bonyoung, and Sokhee P. Jung. "Trends and perspectives of microbial electrolysis cell technology for ultimate green hydrogen production." Journal of Korean Society of Environmental Engineers 44, no. 10 (October 31, 2022): 383–96. http://dx.doi.org/10.4491/ksee.2022.44.10.383.
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Currently, gray hydrogen and blue hydrogen are widely recognized as renewable energy, but in reality, they are made from fossil fuels. The most important task to achieve the hydrogen-based society is the development of economic green hydrogen production technology. Microbial electrolysis cell (MEC) is a next-generation energy-producing wastewater treatment technology that treats renewable organic wastewater and simultaneously produces the ultimate green hydrogen. For hydrogen production in MFC, it is necessary to input electrical energy into MEC. However, that energy is all covered by the energy produced by the MEC. Therefore, hydrogen production in MEC can be defined as the ultimate green hydrogen. This review contains an in-depth summary and analysis of the principles and feasibility of MEC technology, the composition and shape of MEC, electrode materials, and practical application cases in various types of wastewaters. Furthermore, compatibility and scalability with other environmental systems were reviewed at the pilot scale. Based on this, the technical limitations of MEC were diagnosed and future research directions for the practical application of MEC technology were suggested.
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Chen, Ruoyu, Yanfang Fan, Mengxin Jia, and Shuang Yuan. "A Game-Theoretic Scheme for Parked Vehicle-Assisted MEC Computation Offloading." Scientific Programming 2022 (August 24, 2022): 1–14. http://dx.doi.org/10.1155/2022/7394689.
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By offloading computation tasks, multi-access edge computing (MEC) supports diverse services and reduces delay and energy consumption of mobile devices (MDs). However, limited resources of edge servers may be the bottleneck for task computing in high-density scenarios. To address this challenge, by leveraging the underutilized resources of parked vehicles to execute tasks, we propose a parked vehicle-assisted multi-access edge computing (PV-assisted MEC) architecture, which enables MEC servers to expand their capability flexibly. To achieve efficient offloading, we propose a PV-assisted MEC offloading scheme in a multi-MD environment. We design a game-based distributed algorithm to minimize the overhead of MDs and further reduce the burden on the MEC server. Simulation results show that compared with the common MEC system, our scheme can reduce the burden on the MEC server by 5% and the offloading overhead by 17%.
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Virdis, Antonio, Giovanni Nardini, Giovanni Stea, and Dario Sabella. "End-to-End Performance Evaluation of MEC Deployments in 5G Scenarios." Journal of Sensor and Actuator Networks 9, no. 4 (December 11, 2020): 57. http://dx.doi.org/10.3390/jsan9040057.
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Multi-access edge computing (MEC) promises to deliver localized computing power and storage. Coupled with low-latency 5G radio access, this enables the creation of high added-value services for mobile users, such as in-vehicle infotainment or remote driving. The performance of these services as well as their scalability will however depend on how MEC will be deployed in 5G systems. This paper evaluates different MEC deployment options, coherent with the respective 5G migration phases, using an accurate and comprehensive end-to-end (E2E) system simulation model (exploiting Simu5G for radio access and Intel CoFluent for core network and MEC), taking into account user-related metrics, such as response time or MEC latency. Our results show that 4G radio access is going to be a bottleneck, preventing MEC services from scaling up. On the other hand, the introduction of 5G will allow a considerable higher penetration of MEC services.
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Rodriguez-Campos, Liliana, Wes Martz, and Rigoberto Rincones-Gómez. "Applying the Model for Collaborative Evaluations to a Multicultural Seminar in a Nonprofit Setting." Journal of MultiDisciplinary Evaluation 6, no. 13 (December 2, 2009): 109–17. http://dx.doi.org/10.56645/jmde.v6i13.253.
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Background: The diversity within organizations and the stakeholders served require an awareness and appreciation of multiple value perspectives. The challenges with respect to the handling of these perspectives and inappropriate biases resulting from poorly chosen value premises reinforce the importance of seeking out and engaging diverse and relevant evaluation stakeholders. Purpose: This article addresses stakeholder engagement in evaluations by presenting an application of the Model for Collaborative Evaluations (MCE) to the evaluation of a multiculturalism seminar. Setting: A nonprofit organization that promotes an understanding of multicultural environments through various programs, including a multiculturalism seminar. Intervention: The article examines the application of the MCE to an organization. Research Design: Single-case study. Data Collection and Analysis: The collaboration team consisted of five members plus an external evaluator. The steps outlined in the MEC were strictly adhered to for fidelity purposes. Data collection was completed using interviews and written questionnaires. Findings: The MEC approach that was used in this formative evaluation actively engaged the key stakeholders during the evaluation process. With a collaborative approach to evaluation decision-making, the collaboration members were able to share their various points of view and, as a result, there was a lower likelihood that a particular idea would be overlooked. The MCE enhanced the quality of the evaluation by establishing an open and shared evaluation environment while attending to the intended and unintended effects of the collaborative relationships. In addition, the MEC provided increased shared ownership in the evaluation that also led to an increased quality of information for decision-making and receptivity of the findings. Keywords: collaborative evaluation, checklists, multiculturalism seminar, nonprofit
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Greene, Paul, George Follett, and Clint Henker. "Munitions and Dredging Experience on the United States Coast." Marine Technology Society Journal 43, no. 4 (October 1, 2009): 127–31. http://dx.doi.org/10.4031/mtsj.43.4.2.
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AbstractA number of dredging projects have unknowingly and unfortunately encountered munitions and explosives of concern (MEC). MEC have been discovered on dredges (e.g., in dragheads, cutterheads, pump casings) and at the dredged material placement site. Detonations have occurred that have either damaged the dredge plant or have even sunk the dredging vessel. A number of recent dredging projects have proactively addressed MEC issues before the start of construction, thereby greatly reducing overall risk and MEC cleanup costs. This paper explains common dredging equipment, discusses techniques useful in reducing the inherent risks of dredging in sediments containing MEC, and discusses lessons learned during various dredging projects involving MEC.Application of MEC avoidance and exclusion techniques during dredging operations is minor compared to the enormous cost of post-dredging MEC cleanup. Most importantly, it is possible to avoid exposing the public to explosive safety hazards and minimize those to workers with proper planning and execution.