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3. Measurement of resistance temperature characteristics of graphite based flexible grounding body with current heating voltammetry

Author

HU Songjiang, CHEN Sifu, LIU Liqin, LI Fulei, DING Weidong, WANG Yang, and CAO Wen

Subjects
graphite based flexible grounding body, resistance temperature characteristic, current heating voltammetry, resistance temperature curve, thermal stability verification, Materials of engineering and construction. Mechanics of materials, TA401-492, Environmental engineering, TA170-171
Abstract

The resistance temperature characteristics and thermal stability of graphite based flexible grounding materials were studied. With the method of current heating and constant temperature protection, the resistance of grounding body at each temperature was measured by voltammetry, and the average resistance temperature coefficient was derived. With the resistance temperature characteristic parameters of the grounding body obtained from the experiment, the maximum temperature rise of the graphite based flexible grounding body under the power frequency grounding fault current and lightning impulse current was calculated iteratively, which is verified by the calculation of the thermal stability coefficient. The experimental results show that the graphite based flexible grounding body has a negative temperature coefficient. When the maximum allowable service temperature of the graphite based flexible grounding body is 450 ℃, the maximum allowable current under 0.5 s power frequency current is about 1.4 kA, which is 8/20 μs the maximum allowable passing current amplitude of graphite based flexible grounding body under the impact of high frequency lightning current is 287.9 kA.

Published
2022
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13. Molecular Epidemiology and Colistin-Resistant Mechanism of mcr -Positive and mc r-Negative Escherichia coli Isolated From Animal in Sichuan Province, China.

Author

Li, Fulei, Cheng, Ping, Li, Xiaoting, Liu, Ruimeng, Liu, Haibin, and Zhang, Xiuying

Subjects
ESCHERICHIA coli, GRAM-negative bacterial diseases, MOLECULAR epidemiology, LIVESTOCK farms, COLISTIN, DRUG resistance in microorganisms
Abstract

Colistin is the last line of defense for the treatment of multidrug-resistant gram-negative bacterial infections. However, colistin resistance is gradually increasing worldwide, with resistance commonly regulated by two-component system and mcr gene. Thus, this study aimed to investigate molecular epidemiology and colistin-resistant mechanism of mcr -positive and mcr -negative Escherichia coli isolates from animal in Sichuan Province, China. In this study, a total of 101 colistin-resistant E. coli strains were isolated from 300 fecal samples in six farms in Sichuan Province. PCR was used to detect mcr gene (mcr-1 to mcr-9). The prevalence of mcr-1 in colistin-resistant E. coli was 53.47% (54/101), and the prevalence of mcr-3 in colistin-resistant E. coli was 10.89% (11/101). The colistin-resistant E. coli and mcr-1 –positive E. coli showed extensive antimicrobial resistance profiles. For follow-up experiments, we used 30 mcr -negative and 30 mcr-1 –positive colistin-resistant E. coli isolates and E. coli K-12 MG1655 model strain. Multi-locus sequence typing (MLST) of 30 strains carrying mcr-1 as detected by PCR identified revealed six strains (20%) of ST10 and three strains (10%) of each ST206, ST48, and ST155 and either two (for ST542 and 2539) or just one for all other types. The conjugation experiment and plasmid replicon type analysis suggest that mcr-1 was more likely to be horizontally transferred and primarily localized on IncX4-type and IncI2-type plasmid. The ST diversity of the mcr-1 indicated a scattered and non-clonal spreading in mcr-1 –positive E. coli. Twenty-eight mcr -negative colistin-resistant E. coli isolates carried diverse amino acid alterations in PmrA, PmrB, PhoP, PhoQ, and MgrB, whereas no mutation was found in the remaining isolates. The finding showed the high prevalence of colistin resistance in livestock farm environments in Sichuan Province, China. Our study demonstrates that colistin resistance is related to chromosomal point mutations including the two-component systems PhoP/PhoQ, PmrA/PmrB, and their regulators MgrB. These point mutations may confer colistin resistance in mcr -negative E. coli. These findings help in gaining insight of chromosomal-encoded colistin resistance in E. coli. [ABSTRACT FROM AUTHOR]

Published
2022
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14. Prevalence and molecular epidemiology characteristics of carbapenem-resistant

Author

Cheng, Ping, Li, Fulei, Liu, Ruimeng, Yang, Yuqi, Xiao, Tianshi, Ishfaq, Muhammad, Xu, Guofeng, and Zhang, Xiuying

Subjects
carbapenem-resistant, Infection and Drug Resistance, fitness cost, Escherichia coli, NDM-1, Original Research
Abstract

Ping Cheng,1 Fulei Li,1 Ruimeng Liu,1 Yuqi Yang,1 Tianshi Xiao,1 Muhammad Ishfaq,1 Guofeng Xu,2 Xiuying Zhang11Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, People’s Republic of China; 2First Department of Respiratory Disease, Inflammation and Allergic Diseases Research Unit, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, People’s Republic of ChinaObjective: This retrospective study was conducted to determine the prevalence and molecular epidemiology characteristics of carbapenem-resistant Escherichia coli (CRE).Methods: A total of 593 Escherichia coli (E. coli) isolates were recovered from pigs and urban river from 2009 to 2014 in Heilongjiang Province of China. Forty CRE including 22 strains isolated from fecal samples of pigs and 18 strains isolated from water samples were selected. PCR detection of resistance determinants, multi-locus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and phylogenetic groups were performed to characterize CRE isolates. Conjugation experiments, plasmid stability testing, PCR-based replicon typing (PBRT), and PCR mapping were conducted to analyze blaNDM-carrying plasmids. In vitro time–growth studies and competition experiments were carried out to assess the fitness impact of NDM carriage.Results: Five NDM-1-positive E. coli isolates were identified from water samples. Genetic environment analysis revealed that a cluster of genes (ISAba125-blaNDM-1-bleMBL-ΔtrpF) was detected in all of the NDM-1-positive isolates. Conjugation assays showed that blaNDM-1 could be successfully transferred to E. coli J53 from 5 donor strains at frequencies of 4.6×10−5 to 2.6×10−2. The plasmids from all transconjugants belonged to different plasmid replicon types including IncA/C (n=2), IncFII (n=1) and IncX3 (n=2). In vitro time–growth studies revealed that blaNDM-1 did not have a significant impact on cell proliferation. Meanwhile, competition experiments showed that the acquisition of blaNDM-1 can place an energy burden on the bacterial host and incur fitness cost. However, plasmid stability testing showed that blaNDM-1-carrying plasmid remained stable in the hosts after seven passages without antimicrobial selection.Conclusion: The study revealed the early molecular epidemiology and dissemination characteristics of CRE. In addition, the overall antimicrobial resistance in E. coli recovered from water samples is higher than the strains isolated from fecal samples of pigs. Furthermore, we isolated and identified five NDM-1-producing E. coli strains from water samples.Keywords: carbapenem-resistant, Escherichia coli, NDM-1, fitness cost

Published
2019

15. Prevalence and molecular epidemiology characteristics of carbapenem-resistant Escherichia coli in Heilongjiang Province, China

Author

Cheng,Ping, Li,Fulei, Liu,Ruimeng, Yang,Yuqi, Xiao,Tianshi, Ishfaq,Muhammad, Xu,Guofeng, Zhang,Xiuying, Cheng,Ping, Li,Fulei, Liu,Ruimeng, Yang,Yuqi, Xiao,Tianshi, Ishfaq,Muhammad, Xu,Guofeng, and Zhang,Xiuying

Abstract

Ping Cheng,1 Fulei Li,1 Ruimeng Liu,1 Yuqi Yang,1 Tianshi Xiao,1 Muhammad Ishfaq,1 Guofeng Xu,2 Xiuying Zhang11Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Faculty of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, People’s Republic of China; 2First Department of Respiratory Disease, Inflammation and Allergic Diseases Research Unit, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, People’s Republic of ChinaObjective: This retrospective study was conducted to determine the prevalence and molecular epidemiology characteristics of carbapenem-resistant Escherichia coli (CRE).Methods: A total of 593 Escherichia coli (E. coli) isolates were recovered from pigs and urban river from 2009 to 2014 in Heilongjiang Province of China. Forty CRE including 22 strains isolated from fecal samples of pigs and 18 strains isolated from water samples were selected. PCR detection of resistance determinants, multi-locus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and phylogenetic groups were performed to characterize CRE isolates. Conjugation experiments, plasmid stability testing, PCR-based replicon typing (PBRT), and PCR mapping were conducted to analyze blaNDM-carrying plasmids. In vitro time–growth studies and competition experiments were carried out to assess the fitness impact of NDM carriage.Results: Five NDM-1-positive E. coli isolates were identified from water samples. Genetic environment analysis revealed that a cluster of genes (ISAba125-blaNDM-1-bleMBL-ΔtrpF) was detected in all of the NDM-1-positive isolates. Conjugation assays showed that blaNDM-1 could be successfully transferred to E. coli J53 from 5 donor strains at frequencies of 4.6×10−5 to 2.6×10−2. The plasmids from all transconjugants belonged to different plasmid replicon ty

Published
2019

16. Antimicrobial Resistance and Virulence Profiles of mcr-1–Positive Escherichia coliIsolated from Swine Farms in Heilongjiang Province of China

Author

Cheng, Ping, Yang, Yuqi, Zhang, Junchuan, Li, Fulei, Li, Xiaoting, Liu, Haibin, Ishfaq, Muhammad, Xu, Guofeng, and Zhang, Xiuying

Abstract

The emergence and global distribution of the mcr-1gene for colistin resistance have become a public concern because of threats to the role of colistin as the last line of defense against some bacteria. Because of the prevalence of mcr-1–positive Escherichia coliisolates in food animals, production of these animals has been regarded as one of the major sources of amplification and spread of mcr-1. In this study, 249 E. coliisolates were recovered from 300 fecal samples collected from swine farms in Heilongjiang Province, People's Republic of China. Susceptibility testing revealed that 186 (74.70%) of these isolates were colistin resistant, and 86 were positive for mcr-1. The mcr-1–positive isolates had extensive antimicrobial resistance profiles and additional resistance genes, including blaTEM, blaCTX-M, aac3-IV, tet(A), floR, sul1, sul2, sul3,and oqxAB. No mutations in genes pmrABand mgrBwere associated with colistin resistance. Phylogenetic group analysis revealed that the mcr-1–positive E. coliisolates belonged to groups A (52.33% of isolates), B1 (33.72%), B2 (5.81%), and D (8.14%). The prevalence of the virulence-associated genes iutA, iroN, fimH, vat, ompA,and traTwas moderate. Seven mcr-1–positive isolates were identified as extraintestinal pathogenic. Among 20 mcr-1–positive E. coliisolates, multilocus sequence typing revealed that sequence type 10 was the most common (five isolates). The conjugation assays revealed that the majority of mcr-1genes were transferable at frequencies of 7.05 × 10−7to 7.57 × 10−4. The results of this study indicate the need for monitoring and minimizing the further dissemination of mcr-1among E. coliisolates in food animals, particularly swine.

Published
2020
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17. An Analysis of the Factors that Determine the Foreign Exchange Rate for USD/GBP (Cable)

Author

Li, Fulei and Li, Fulei

Abstract

The following study focuses on the connection between ten nominated factors and high frequent transaction currency, using the USD/GBP rate. These ten factors were taken from Parity approach, Balance of payments approach, monetary approach, Assets approach, and macroeconomic variants intricately related to Cable. The examination range went through financial crisis between 2008 and 2013, according to the above ten variables with Cable. Through multivariate regression and VIF, the impact on Cable can be understood, along with multicollinearity amongst factors. A crucially negative connection exists between the cross exchange rate (EUR/GBP) and Cable (USD/GBP). Furthermore, CPI, inflation rate differential, balance of payment, and assets approaches showed a poor negative connection with Cable, which is against the hypotheses of this time. The remaining variables were lessened by multiple external factors, for which there could not be a clear and important connection found. Keywords: exchange rate; Cable; Multivariate regression; relationship; multicollinearity.

18. An Analysis of the Factors that Determine the Foreign Exchange Rate for USD/GBP (Cable)

Author

Li, Fulei and Li, Fulei

Abstract

The following study focuses on the connection between ten nominated factors and high frequent transaction currency, using the USD/GBP rate. These ten factors were taken from Parity approach, Balance of payments approach, monetary approach, Assets approach, and macroeconomic variants intricately related to Cable. The examination range went through financial crisis between 2008 and 2013, according to the above ten variables with Cable. Through multivariate regression and VIF, the impact on Cable can be understood, along with multicollinearity amongst factors. A crucially negative connection exists between the cross exchange rate (EUR/GBP) and Cable (USD/GBP). Furthermore, CPI, inflation rate differential, balance of payment, and assets approaches showed a poor negative connection with Cable, which is against the hypotheses of this time. The remaining variables were lessened by multiple external factors, for which there could not be a clear and important connection found. Keywords: exchange rate; Cable; Multivariate regression; relationship; multicollinearity.

19. An Analysis of the Factors that Determine the Foreign Exchange Rate for USD/GBP (Cable)

Author

Li, Fulei and Li, Fulei

Abstract

The following study focuses on the connection between ten nominated factors and high frequent transaction currency, using the USD/GBP rate. These ten factors were taken from Parity approach, Balance of payments approach, monetary approach, Assets approach, and macroeconomic variants intricately related to Cable. The examination range went through financial crisis between 2008 and 2013, according to the above ten variables with Cable. Through multivariate regression and VIF, the impact on Cable can be understood, along with multicollinearity amongst factors. A crucially negative connection exists between the cross exchange rate (EUR/GBP) and Cable (USD/GBP). Furthermore, CPI, inflation rate differential, balance of payment, and assets approaches showed a poor negative connection with Cable, which is against the hypotheses of this time. The remaining variables were lessened by multiple external factors, for which there could not be a clear and important connection found. Keywords: exchange rate; Cable; Multivariate regression; relationship; multicollinearity.

20. An Analysis of the Factors that Determine the Foreign Exchange Rate for USD/GBP (Cable)

Author

Li, Fulei and Li, Fulei

Abstract

The following study focuses on the connection between ten nominated factors and high frequent transaction currency, using the USD/GBP rate. These ten factors were taken from Parity approach, Balance of payments approach, monetary approach, Assets approach, and macroeconomic variants intricately related to Cable. The examination range went through financial crisis between 2008 and 2013, according to the above ten variables with Cable. Through multivariate regression and VIF, the impact on Cable can be understood, along with multicollinearity amongst factors. A crucially negative connection exists between the cross exchange rate (EUR/GBP) and Cable (USD/GBP). Furthermore, CPI, inflation rate differential, balance of payment, and assets approaches showed a poor negative connection with Cable, which is against the hypotheses of this time. The remaining variables were lessened by multiple external factors, for which there could not be a clear and important connection found. Keywords: exchange rate; Cable; Multivariate regression; relationship; multicollinearity.

21. Inosine reverses multidrug resistance in Gram-negative bacteria carrying mobilized RND-type efflux pump gene cluster tmexCD-toprJ .

Author

Li F, Xu T, Fang D, Wang Z, and Liu Y

Subjects
Bacterial Proteins genetics, Bacterial Proteins metabolism, Microbial Sensitivity Tests, Inosine pharmacology, Inosine metabolism, Drug Resistance, Multiple, Bacterial genetics, Drug Resistance, Multiple, Bacterial drug effects, Tigecycline pharmacology, Anti-Bacterial Agents pharmacology, Gram-Negative Bacteria drug effects, Gram-Negative Bacteria genetics, Membrane Transport Proteins genetics, Membrane Transport Proteins metabolism, Multigene Family
Abstract

Antimicrobial resistance is rapidly increasing worldwide, highlighting the urgent need for pharmaceutical and nonpharmaceutical interventions to tackle different-to-treat bacterial infections. Tigecycline, a semi-synthesis glycylcycline for parenteral administration, is widely recognized as one of the few effective therapies available against pan-drug resistant Gram-negative pathogens. Regrettably, the efficacy of multiple drugs, including tigecycline, is currently being undermined due to the emergence of a recently discovered mobilized resistance-nodulation-division-type efflux pump gene cluster tmexCD1-toprJ1 . Herein, by employing untargeted metabolomic approaches, we reveal that the expression of tmexCD1-toprJ1 disrupts bacterial purine metabolism, with inosine being identified as a crucial biomarker. Notably, the supplementation of inosine effectively reverses tigecycline resistance in tmexCD1-toprJ1 -positive bacteria. Mechanistically, exogenous inosine enhanced bacterial proton motive force, which promotes the uptake of tigecycline. Furthermore, inosine enhances succinate biosynthesis by stimulating the tricarboxylic acid cycle. Succinate interacts with the two-component system EnvZ/OmpR and upregulates OmpK 36, thereby promoting the influx of tigecycline. These actions collectively lead to the increased intracellular accumulation of tigecycline. Overall, our study offers a distinct combinational strategy to manage infections caused by tmexCD-toprJ -positive bacteria., Importance: TMexCD1-TOprJ1, a mobilized resistance-nodulation-division-type efflux pump, confers phenotypic resistance to multiple classes of antibiotics. Nowadays, tmexCD-toprJ has disseminated among diverse species of clinical pathogens, exacerbating the need for novel anti-infective strategies. In this study, we report that tmexCD1-toprJ1 -negative and -positive bacteria exhibit significantly different metabolic flux and characteristics, especially in purine metabolism. Intriguingly, the addition of inosine, a purine metabolite, effectively restores the antibacterial activity of tigecycline by promoting antibiotic uptake. Our findings highlight the correlation between bacterial mechanism and antibiotic resistance, and offer a distinct approach to overcome tmexCD-toprJ -mediated multidrug resistance., Competing Interests: The authors declare no conflict of interest.

Published
2024
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