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Long-term hypertension can lead to hypertensive heart disease, which ultimately progresses to heart failure. As an angiotensin receptor blocker antihypertensive drug, allisartan can control blood pressure, and improve cardiac remodeling and cardiac dysfunction caused by hypertension. The aim of the present study was to investigate the protective effects of allisartan on the heart of spontaneously hypertensive rats (SHRs) and the underlying mechanisms. SHRs were used as an animal model of hypertensive heart disease and were treated with allisartan orally at a dose of 25 mg/kg/day. The blood pressure levels of the rats were continuously monitored, their body and heart weights were measured, and their cardiac structure and function were evaluated using echocardiography. Wheat germ agglutinin staining and Masson trichrome staining were employed to assess the morphology of the myocardial tissue. In addition, transcriptome and proteome analyses were performed using the Solexa/Illumina sequencing platform and tandem mass tag technology, respectively. Immunofluorescence co-localization was conducted to analyze Nrf2 nuclear translocation, and TUNEL was performed to detect the levels of cell apoptosis. The protein expression levels of pro-collagen I, collagen III, phosphorylated (p)-AKT, AKT, p-PI3K and PI3K, and the mRNA expression levels of Col1a1 and Col3a1 were determined by western blotting and reverse transcription-quantitative PCR, respectively. Allisartan lowered blood pressure, attenuated cardiac remodeling and improved cardiac function in SHRs. In addition, allisartan alleviated cardiomyocyte hypertrophy and cardiac fibrosis. Allisartan also significantly affected the 'pentose phosphate pathway', 'fatty acid elongation', 'valine, leucine and isoleucine degradation', 'glutathione metabolism', and 'amino sugar and nucleotide sugar metabolism' pathways in the hearts of SHRs, and upregulated the expression levels of GSTM2. Furthermore, allisartan activated the PI3K-AKT-Nrf2 signaling pathway and inhibited cardiomyocyte apoptosis. In conclusion, the present study demonstrated that allisartan can effectively control blood pressure in SHRs, and improves cardiac remodeling and cardiac dysfunction. Allisartan may also upregulate the expression levels of GSTM2 in the hearts of SHRs and significantly affect glutathione metabolism, as determined by transcriptome and proteome analyses. The cardioprotective effect of allisartan may be mediated through activation of the PI3K-AKT-Nrf2 signaling pathway, upregulation of GSTM2 expression and reduction of cardiomyocyte apoptosis in SHRs. [ABSTRACT FROM AUTHOR]

Background: Metabolic remodeling plays a vital role in the development of heart failure. The trimetazidine can optimize fatty acid and glucose oxidation via inhibition of long-chain 3-ketoacyl CoA thiolase in the heart. So, trimetazidine commonly used in cardiovascular therapy as a myocardial metabolic drug. This study was conducted to assess the effects and mechanisms of trimetazidine on ketone body metabolism in heart failure rats. Methods: A rat model of heart failure was established by continuous subcutaneous injection of isoproterenol in 10 mg/kg/d. We examined body weight, heart weight index, and tested B-type natriuretic peptide by kit. We detected the structure and function of the heart. Hematoxylin-eosin staining and Masson's trichrome staining was performed to assess myocardial tissue morphology. To evaluate apoptosis, we used Tunel staining. Metabolic substrate contents of glucose, free fatty acid, ketone bodies, lactic acid, and pyruvate and ATP levels in myocardial tissues were measured with the corresponding kit. We detected the levels of protein expressions related to myocardial substrate uptake and utilization by Western blot. Results: Trimetazidine remarkably reduced the heart weight index and B-type natriuretic peptide levels. Besides, trimetazidine increased the level of blood pressure and decreased heart rate. Moreover, trimetazidine inhibited decreases in left ventricular ejection fraction and left ventricular fractional shortening. Further, trimetazidine decreased the levels of collagen volume fraction and promoted ATP production in myocardial tissues. Trimetazidine also reduced the levels of free fatty acid, ketone bodies, lactic acid, and increased glucose and pyruvate levels in myocardial tissues. Furthermore, trimetazidine markedly inhibited apoptosis. More importantly, the protein expression levels related to myocardial substrate uptake and utilization increased dramatically in the trimetazidine group. In particular, the protein expressions related to ketone body utilization were prominent. Conclusions: Trimetazidine could attenuate metabolic remodeling and improve cardiac function in heart failure rats. The potential mechanism for the cardioprotective effect of trimetazidine may be highly associated with its regulation of adenosine monophosphate-activated protein kinase, and peroxisome proliferator activated receptor α expressions. Along with the regulation, myocardial substrate utilization was improved, especially the utilization of ketone bodies. [ABSTRACT FROM AUTHOR]

Background: The plasmid-encoded multidrug efflux pump oqxAB confers bacterial resistance primarily to olaquindox, quinolones, and chloramphenicol. The aims of this study were to investigate the prevalence of oqxAB among Escherichia coli isolates from dogs, cats, and humans in Henan, China and the susceptibilities of E. coli isolates to common antibiotics. Methods: From 2012 to 2014, a total of 600 samples which included 400 rectal samples and 200 clinical human specimens were tested for the presence of E. coli. All isolates were screened for oqxAB genes by PCR and sequencing. The MICs of 11 antimicrobial agents were determined by the broth microdilution method. A total of 30 representative oqxAB-positive isolates were subjected to ERIC-PCR and MLST. Additionally, conjugation experiments and southern hybridizations were performed. Results: Of 270 isolates, 58.5% (62/106) of the isolates from dogs, 56.25% (36/64) of the isolates from cats, and 42.0% (42/100) of the isolates from humans were positive for the oqxAB. Olaquindox resistance was found for 85.7%-100% of oqxAB-positive isolates. Of oqxAB-positive isolates from dogs, cats, and humans, ciprofloxacin resistance was inspected for 85.8%, 59.1%, and 93.8%, respectively. Several oqxAB-positive isolates were demonstrated by ERIC-PCR and MLST, and have high similarity. Phylogenetic analysis showed that oqxAB-positive isolates could be divided into 7 major clusters. OqxAB-positive conjugants were obtained, southern hybridization verified that the oqxAB gene complex was primarily located on plasmids. Conclusion: In conclusion, oqxAB-positive isolates were widespread in animals and humans in Henan, China. Carriage of oqxAB on plasmids of E. coli isolates may facilitate the emergence of multidrug resistant and its transmission via horizontal transfer, and might pose a potential threat to public health. [ABSTRACT FROM AUTHOR]

It has been recognized that colistin resistance is a growing problem that seriously impairs the clinical efficacy of colistin against bacterial infections. One strategy that has been proven to have therapeutic effect is to overcome the widespread emergence of antibiotic-resistant pathogens by combining existing antibiotics with promising non-antibiotic agents. In this work, antibiotic susceptibility testing, checkerboard assays and time-kill curves were used to investigate the antibacterial activity of the individual drugs and the potential synergistic activity of the combination. The molecular mechanisms of tetrandrine in combination with colistin were analyzed using fluorometric assay and Real-time PCR. To predict possible interactions between tetrandrine and MCR-1, molecular docking assay was taken. Finally, we evaluated the in vivo efficacy of tetrandrine in combination with colistin against MCR-positive Salmonella. Overall, the combination of tetrandrine and colistin showed significant synergistic activity. In-depth mechanistic analysis showed that the combination of tetrandrine with colistin enhances the membrane-damaging ability of colistin, undermines the functions of proton motive force (PMF) and efflux pumps in MCR-positive bacteria. The results of molecular docking and RT-PCR analyses showed that tetrandrine not only affects the expression of mcr -1 but is also an effective MCR-1 inhibitor. Compared with colistin monotherapy, the combination of tetrandrine with colistin significantly reduced the bacterial load in vivo. Our findings demonstrated that tetrandrine serves as a potential colistin adjuvant against MCR-positive Salmonella. • In our study, the combination of tetrandrine and colistin drastically enhanced colistin bactericidal activity compared with monotreatment. • In-depth mechanistic analysis showed that tetrandrine potentiated colistin activity through enhancing the membrane-damaging ability of colistin. • Tetrandrine dramatically undermines the function of PMF and result in decreased intracellular ATP levels. In addition, the activity of efflux pump was significantly inhibited by the addition of tetrandrine in both single or combination treatments. • Tetrandrine not only affects the expression of mcr -1 but also as an effective MCR-1 inhibitor. • The discovery of tetrandrine as a potential adjuvant for colistin therapy in combination therapy for severe infections caused by MCR-1 positive Salmonella. [ABSTRACT FROM AUTHOR]

The emergence and rapid spread of multi-drug-resistant (MDR) bacteria pose a serious threat to global healthcare. Although the synergistic effect of rafoxanide and colistin was reported, little is known regarding the potential mechanism of this synergy, particularly against chromosomal-mediated colistin-resistant Klebsiella pneumoniae . In the present study, we elucidated the synergistic effect of rafoxanide and colistin against chromosomal-mediated colistin-resistant Klebsiella pneumoniae isolates from human (KP-9) and swine (KP-1) infections. Treatment with 1 mg/L rafoxanide overtly reversed the MIC max to 512-fold. Time-kill assays indicated that rafoxanide acted synergistically with colistin against the growth of KP-1 and KP-9. Mechanistically, we unexpectedly found that the combination destroys the inner-membrane integrity, and ATP synthesis was also quenched, albeit, not via F 1 F 0 -ATPase; thereby also inhibiting the activity of efflux pumps. Excessive production of reactive oxygen species (ROS) was also an underlying factor contributing to the bacterial-killing effect of the combination. Transcriptomic analysis unraveled overt heterogeneous expression as treated with both administrations compared with monotherapy. Functional analysis of these differentially expressed genes (DEGs) targeted to the plasma membrane and ATP-binding corroborated phenotypic screening results. These novel findings highlight the synergistic mechanism of rafoxanide in combination with colistin which effectively eradicates chromosomal-mediated colistin-resistant Klebsiella pneumoniae . IMPORTANCE The antimicrobial resistance of Klebsiella pneumoniae caused by the abuse of colistin has increased the difficulty of clinical treatment. A promising combination (i.e., rafoxanide+ colistin) has successfully rescued the antibacterial effect of colistin. However, we still failed to know the potential effect of this combination on chromosome-mediated Klebsiella pneumoniae . Through a series of in vitro experiments, as well as transcriptomic profiling, we confirmed that the MIC of colistin was reduced by rafoxanide by destroying the inner-membrane integrity, quenching ATP synthesis, inhibiting the activity of the efflux pump, and increasing the production of reactive oxygen species. In turn, the expression of relevant colistin resistance genes was down-regulated. Collectively, our study revealed rafoxanide as a promising colistin adjuvant against chromosome-mediated Klebsiella pneumoniae ., Competing Interests: The authors declare no conflict of interest.

Integrative conjugative elements (ICEs) are important carriers for disseminating resistance genes. We have previously reported a novel element ICE Hpa1 carrying seven antibiotic resistance genes, which could be self-transmissible relying on the novel T4SS. To identify novel ICE Hpa1 variants from 211 strains and novel T4SS encoded in ICE Hpa1 , and to explore the relationships in these ICEs, four complete sequences of ICEs were identified by WGS analysis and antimicrobial susceptibility testing was determined by broth microdilution. In addition, a comparative analysis of these ICEs was conducted with bioinformatic tools, and the transfer abilities of these ICEs were confirmed by conjugation. Four ICE Hpa1 variants ICE Gpa1818 , ICE Gpa1808 , ICE Gpa1807 , and ICE Gpa1815 with different resistance gene profiles were characterized, and their hosts showed different resistance spectrums. All ICEs shared the same backbone and were inserted into the tRNA Leu site, and all resistance regions were inserted into the same target site between the accessory and integration regions. This study analyzed complete sequences of ICEs from the ICE Hpa1 family and identified novel T4SS and insertion element IS Gpa2 . Diverse resistance genes extensively exist in these ICEs, serving as a reservoir for resistance genes and facilitating their dissemination., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sun, Zhang, Miao, Zhai, Pan, Yuan, Yan, Wu and Hu.)

Introduction. The bla CTX-M-3 gene has rarely been reported in Morganella morganii strains and its genetic environment has not yet been investigated. Aim. To identify the bla CTX-M-3 gene in M. morganii isolated from swine and characterize its genetic environment. Methodology. A M. morganii isolate (named MM1L5) from a deceased swine was identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and subjected to antimicrobial susceptibility testing. The bla genes were detected and then the genetic location and environment of bla CTX-M-3 were investigated by Southern blot and PCR mapping, respectively. The M. morganii bla CTX-M-3 gene was cloned and expressed in Escherichia coli . Results. Isolate MM1L5 harboured the bla CTX-M-3 and bla TEM-1 genes. The bla CTX-M-3 gene, located on the chromosome, was co-carried with an IS 26 and bla TEM-1 gene by a novel 6361 bp IS 26 -flanked composite transposon, designated Tn 6741 . This transposon consisted of a novel bla CTX-M-3 -containing module, IS 26 -ΔIS Ecp1-bla CTX-M-3 -Δ orf477 -IS 26 (named Tn 6710 ), and a bla TEM-1 -containing module, IS 26 -Δ orf477-bla TEM-1 -tnpR-IS 26 , differing from previous reports. Phylogenetic analysis showed a significant variation based on the sequence of Tn 6741 , as compared to those of other related transposons. Interestingly, although the cloned bla CTX-M-3 gene could confer resistance to ceftiofur, cefquinome, ceftriaxone and cefotaxime, one amino acid substitution (Ile-142-Thr) resulted in a significant reduction of resistance to these antimicrobials. Conclusion. This is the first time that bla CTX-M-3 has been identified on a chromosome from a M. morganii isolate. Furthermore, the bla CTX-M-3 gene was located with an IS 26 element and bla TEM-1 gene on a novel IS 26 -flanked composite transposon, Tn 6741 , suggesting that Tn 6741 might act as a reservoir for the bla CTX-M-3 and bla TEM-1 genes and may become an important vehicle for their dissemination among M. morganii .