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BACKGROUND: Urinary tract infections (UTIs) are common bacterial infections, primarily caused by uropathogenic Escherichia coli (UPEC), leading to significant health issues and economic burden. Although antibiotics have been effective in treating UPEC infections, the rise of antibiotic-resistant strains hinders their efficacy. Hence, identifying novel bacterial targets for new antimicrobial approaches is crucial. Bacterial factors required for maintaining the full virulence of UPEC are the potential target. MepM, an endopeptidase in E. coli, is involved in the biogenesis of peptidoglycan, a major structure of bacterial envelope. Given that the bacterial envelope confronts the hostile host environment during infections, MepM's function could be crucial for UPEC's virulence. This study aims to explore the role of MepM in UPEC pathogenesis. RESULTS: MepM deficiency significantly impacted UPEC's survival in urine and within macrophages. Moreover, the deficiency hindered the bacillary-to-filamentous shape switch which is known for aiding UPEC in evading phagocytosis during infections. Additionally, UPEC motility was downregulated due to MepM deficiency. As a result, the mepM mutant displayed notably reduced fitness in causing UTIs in the mouse model compared to wild-type UPEC. CONCLUSIONS: This study provides the first evidence of the vital role of peptidoglycan endopeptidase MepM in UPEC's full virulence for causing UTIs. MepM's contribution to UPEC pathogenesis may stem from its critical role in maintaining the ability to resist urine- and immune cell-mediated killing, facilitating the morphological switch, and sustaining motility. Thus, MepM is a promising candidate target for novel antimicrobial strategies.

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Exposure to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in utero can result in high rates of cleft palate (CP) formation, yet the underlying mechanisms remain to be characterized. In vivo, the lncRNA Meg3 was upregulated following TCDD treatment in CP-associated murine embryonic palatal tissue, with concomitant changes in proliferative and apoptotic activity in these murine embryonic palatal mesenchymal (MEPM) cells. Meg3 can modulate the TGF-ß/Smad to control the proliferation, survival, and differentiation of cells. Accordingly, TCCD and TGF-ß1 were herein used to treat MEPM cells in vitro, revealing that while TCDD exposure altered the proliferative activity and apoptotic death of these cells, exogenous TGF-ß1 exposure antagonized these effects via TGF-ß/Smad signaling. TCDD promoted Meg3 upregulation, whereas TGF-ß1 suppressed TCDD-driven upregulation of this lncRNA. Meg3 was additionally determined to directly interact with Smad2, with significant Meg3 enrichment in Smad2-immunoprecipitates following TCDD treatment. When Meg3 was silenced, the impact of TCDD on Smad signaling, proliferative activity, and apoptosis were ablated, while the effects of exogenous TGF-ß1 were unchanged. This supports a model wherein Meg3 is upregulated in TCDD-exposed palatal tissue whereupon it can interact with Smad2 to suppress Smad-dependent signaling, thus controlling MEPM cell proliferation and apoptosis, contributing to TCDD-induced CP, which provides a theoretical support for the precautions of cleft palate induced by TCDD.

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All-trans retinoic acid (atRA) is a teratogen that can induce cleft palate formation. During palatal development, murine embryonic palate mesenchymal (MEPM) cell proliferation is required for the appropriate development of the palatal frame, with Meg3 serving as a key regulator of the proliferative activity of these cells and the associated epithelial-mesenchymal transition process. DNA methylation and signaling via the TGFß/Smad pathway are key in regulating embryonic development. Here, the impact of atRA on MEPM cell proliferation and associations between Tgfß2 promoter methylation, Meg3, and signaling via the Smad pathway were explored using C57BL/6 N mice treated with atRA (100 mg/kg) to induce fetal cleft palate formation. Immunohistochemistry and BrdU assays were used to detect MEPM proliferation and DNA methylation assays were performed to detect Tgfß2 promoter expression. These analyses revealed that atRA suppressed MEPM cell proliferation, promoted the upregulation of Meg3, and reduced the levels of Smad2 and Tgfß2 expression phosphorylation, whereas Tgfß2 promoter methylation was unaffected. RNA immunoprecipitation experiments indicated that the TgfßI receptor is directly targeted by Meg3, suggesting that the ability of atRA to induce cleft palate may be mediated through the Tgfß/Smad signaling pathway.

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Peptidoglycan (PG) hydrolases play important roles in various aspects of bacterial physiology, including cytokinesis, PG synthesis, quality control of PG, PG recycling, and antibiotic resistance. However, the regulatory mechanisms of their expression are poorly understood. In this study, we have uncovered novel regulatory mechanisms of the protein levels of the synthetically lethal PG endopeptidases MepS and MepM, which are involved in PG synthesis. A mutant defective for both MepS and MepM was lethal in an amino acid-rich medium, whereas it exhibited almost normal growth in a minimal medium, suggesting the expendability of MepS and MepM in a minimal medium. Protein levels of MepS and MepM dramatically decreased in the minimal medium. Although MepM was revealed as a substrate of Prc, a periplasmic protease involved in the proteolysis of MepS, only the decrease in the MepS level in the minimal medium was affected by the prc depletion. Phenotypic and biochemical analyses showed that the presence of aromatic amino acids in the medium induced the accumulation of MepS, but not MepM, while the presence of glutamate increased the level of MepM, but not MepS. Together, these results demonstrate that the protein levels of the two major PG endopeptidases are regulated in an amino acid availability-dependent manner, but their molecular mechanisms and signaling are significantly distinct.

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A 52-year-old man presented to our hospital complaining of general malaise, cough, and fever. Total body computed tomography revealed scattered pneumonia and urethral foreign bodies that had been inserted during adolescence. Candida glabrata was detected in blood and urine cultures. Based on these findings, the patient was diagnosed with candidemia that developed due to Candida urinary tract infection, complicated by septic pulmonary embolism and severe diabetes mellitus. Candidemia likely persisted despite the initiation of intravenous antifungal therapy and control of blood sugar level. Therefore, surgical removal of the urethral foreign bodies was performed, which resulted in resolution of the patient's symptoms. Herein, we report a rare case of candidemia complicated by Candida urinary tract infection that developed due to the long-term presence of urethral foreign bodies. A multidisciplinary therapeutic approach, including surgical removal of the infected foreign bodies, is effective in such cases. This case indicates that long-term presence of foreign bodies and acquired immune dysfunction can be risk factors for candidemia. Therefore, detailed history should be obtained and systemic examination should be performed to identify the complicating risk factors on diagnosis of candidemia.

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Mesenchymal cell proliferation is critical for the growth of the palate shelf. All-trans retinoic acid (atRA), as well as pathways associated with TGF-ß/Smad signaling, play crucial roles in the proliferation of mouse embryonic palate mesenchymal (MEPM) cells. We have found that MEPM-cell proliferation was regulated by atRA and exogenous TGF-ß3 could significantly antagonize the atRA-mediated suppression of MEPM cell proliferation, which is closely associated with the regulation of TGF-ß/Smad signaling pathway. The long non-coding RNA (lncRNA) MEG3 has been reported to activate TGF-ß/Smad signaling, thereby regulating cellular proliferation, differentiation, and related processes. Here, we found that Meg3 expression increased significantly in atRA-treated MEPM cells while TGF-ß3 treatment markedly inhibited Meg3 expression and antagonized the effect of atRA on Meg3. Moreover, Smad2 was found to interact directly with Meg3, and atRA treatment significantly enriched Meg3 in Smad2-immunoprecipitated samples. After Meg3 deletion, the effects of atRA on the proliferation of MEPM cells and TGF-ß3-dependent protein expression were lost. Hence, we speculate that Meg3 has a role in the RA-induced suppression of MEPM cell proliferation by targeting Smad2 and thereby mediating TGF-ß/Smad signaling inhibition.

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Palatal mesenchymal cell proliferation is essential to the process of palatogenesis, and the proliferation of mouse embryonic palate mesenchymal (MEPM) cells is impacted by both all-trans retinoic acid (atRA) and the TGF-ß/Smad signaling pathway. The long non-coding RNA (lncRNA) MEG3 has been shown to activate TGF-ß/Smad signaling and to thereby regulate cell proliferation, differentiation, and related processes. Herein, we found that atRA treatment (100 mg/kg) promoted Meg3 upregulation in MEPM cells, and that such upregulation was linked to the suppression of MEPM cell proliferation in the context of secondary palate fusion on gestational day (GD) 13 and 14. Moreover, the demethylation of specific CpG sites within the lncRNA Meg3 promoter was detected in atRA-treated MEPM cells, likely explaining the observed upregulation of this lncRNA. Smad signaling was also suppressed by atRA treatment in these cells, and RNA immunoprecipitation analyses revealed that Smad2 can directly interact with Meg3 in MEPM cells following atRA treatment. Therefore, we propose a model wherein Meg3 is involved in the suppression of MEPM cell proliferation, functioning at least in part via interacting with the Smad2 protein and thereby suppressing Smad signaling in the context of atRA-induced cleft palate.

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Peptidoglycan (PG) is an essential component of the bacterial exoskeleton that plays a pivotal role in the maintenance of cell shape and resistance to cell lysis under high turgor pressures. The synthesis and degradation of PG must be tightly regulated during bacterial cell elongation and division. Unlike enzymes involved in PG synthesis, PG hydrolases show high redundancy in many bacteria including Escherichia coli. In this study, we showed that PG endopeptidases have distinct roles in cell growth and division. Phenotypic analysis of mutants lacking one of seven PG endopeptidases identified a MepM-specific phenotype, salt sensitivity, and a MepS-specific phenotype, EDTA sensitivity. Complementation test in each phenotype showed that the phenotype of the mepM mutant was restored only by MepM, whereas the phenotype of the mepS mutant was restored by MepS or by overexpression of MepH, PbpG, or MepM. These distinct phenotypes depend on both the specific localizations and specific domains of MepM and MepS. Finally, using the identified phenotypes, we revealed that MepM and MepH were genetically associated with both penicillin-binding protein 1a (PBP1a) and PBP1b, whereas MepS and PbpG were genetically associated with only PBP1b. Notably, a defect in PBP1a or PBP1b phenocopied the mepM mutant, suggesting the importance of MepM on PG synthesis. Therefore, our results indicate that each PG endopeptidase plays a distinct role in cell growth and division, depending on its distinct domains and cellular localizations.

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BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE), especially for carbapenemase-producing Enterobacteriaceae (CPE), is an emerging cause that pose a significant threat to public health. However, efficient therapy has not been established. We assessed the antimicrobial efficacy of meropenem (MEPM) and amikacin (AMK) combination therapy. MATERIAL AND METHODS: Total eight isolates of Escherichia coli or Klebsiella pneumoniae, including CRE and/or CPE have carbapenemase genes were used. The relationship between phenotype and in vivo efficacy was assessed in neutropenic murine thigh infection model. Efficacy was determined using the change in bacterial density and survival rate. RESULTS: The combination therapy showed enhanced antimicrobial activities against CRE+/CPE+ and CRE+/CPE-K. pneumoniae isolates than MEPM monotherapy (0.63 ± 0.04 vs. 2.56 ± 0.24 ⊿log10 cfu/mL, p < 0.05; -1.05 ± 0.15 vs. -0.48 ± 0.30 ⊿log10 cfu/mL, p < 0.05). Likewise, the combination therapy showed enhanced antimicrobial activities against CRE+/CPE+ and CRE+/CPE-E. coli isolates than MEPM monotherapy (0.90 ± 0.68 vs. 1.86 ± 0.23 ⊿log10 cfu/mL, p < 0.05; -1.81 ± 0.06 vs. -0.88 ± 0.23 ⊿log10 cfu/mL, p < 0.05). Also, combination therapy group showed similar to higher survival rates in CRE + E. coli infection mice, compared to MEPM monotherapy group. CONCLUSION: Our results are the first supportive data to threat CRE infections with combination therapy of MEPM and AMK with in vivo model. The current results verify the promising utility of the combination therapy with MEPM and AMK against CRE isolates with a wide range of MEPM MICs.

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BACKGROUND: Treatment of aspiration pneumonia is an important problem due to aging of populations worldwide. However, the effectiveness of cefepime in aspiration pneumonia has not yet been evaluated. AIM: To compare the clinical efficacy and safety of cefepime and meropenem in patients with moderate-to-severe aspiration pneumonia. METHODS: In this open-label, randomized study, either cefepime 1 g or meropenem 0.5 g was administered intravenously every 8 h to patients with moderate-to-severe community-acquired or nursing-home acquired pneumonia at risk for aspiration for an average of 10.5 days. The primary outcome was the clinical response rate at the end of treatment (EOT) in the validated per-protocol (VPP)-population. Secondary outcomes were clinical response during treatment (days 4 and 7) and at the end of study (EOS) in the VPP-population, and survival at day 30 in the modified intention-to-treat (MITT)-population. RESULTS: There was no difference between the groups in the primary or secondary outcomes or safety. Significant improvement was observed in each group on day 4. CONCLUSION: Cefepime is as effective and safe as meropenem in the treatment of moderate-to-severe aspiration pneumonia. CLINICAL TRIALS IDENTIFIER: UMIN000001349.

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2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known environmental teratogenic effector for cleft palate. Transforming growth factor 3 (TGF-ß3) is an essential growth factor for palatogenesis. The objective of this study is to clarify the effects of TCDD and TGF-ß3 in mouse embryonic palatal mesenchymal (MEPM) cells. The effects of 10 nM TCDD, 10 ng/mL TGF-ß3, or a combination of 10 nM TCDD and 10 ng/mL TGF-ß3 on MEPM cells were revealed by cell and biological methods. With the increase in TCDD (0.5-10 nM), the expression of TGF-ß3 increased, but at TCDD concentrations greater than 10 nM, the expression of TGF-ß3 reduced. The viabilities of MEPM cells decreased in the 10 nM TCDD-treated group. But the viabilities increased in the 10 ng/mL TGF-ß3-treated group, and the viabilities were intermediate in the group treated with a combination of 10 nM TCDD and 10 ng/mL TGF-ß3. This phenomenon was the same as that of the motilities. In addition, we found that the expression of p-Smad2, p-Smad3,and Smad7 were increased by TCDD, TGF-ß3, combination of TCDD and TGF-ß3, but the expression of Smad4 were decreased by TCDD, TGF-ß3, combination of TCDD and TGF-ß3. These data revealed that TCDD and TGF-ß3 interacted and affected MEPM cells.

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[This corrects the article DOI: 10.3389/fmicb.2018.02941.].

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2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a well-known environmental teratogenic agent for cleft palate. But transforming growth factor ß3 (TGF-ß3) is an essential growth factor for palatogenesis. This study is to clarify effects of TCDD and TGF-ß3 in mouse embryonic palatal mesenchymal (MEPM) cells. The result showed that with increase of TCDD (0.5 nM-10 nM), the expression of TGF-ß3 increased, but after 10 nM TCDD, the expression of TGF-ß3 reduced. The viabilities of MEPM cells decreased in 10 nM TCDD-treated group. But the viabilities increased in 10 ng/mL TGF-ß3-treated group, or the viabilities were between that of them in combination of 10 nM TCDD and 10 ng/mL TGF-ß3-treated group. This phenomenon was the same as the motilities. In addition, we found that the expression of phosphorylated Smad2/3 and Smad7 was increased by 10 nM TCDD, 10 ng/mL TGF-ß3, or combination of 10 nM TCDD and 10 ng/mL TGF-ß3 induced, but the expression of Smad4 was decreased. These data revealed that the TGF-ß/Smad signaling pathway affected TCDD and TGF-ß3 in MEPM cells.

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A 78 year-old man, who received levofloxacin eye drops as a perioperative prophylactic antibacterial agent for cataract surgery, developed pyrexia and dyspnea, followed by respiratory failure. He was diagnosed as drug-induced lung injury due to levofloxacin, and the symptoms improved after the administration of corticosteroids and discontinuation of levofloxacin eye drops. The incidence of levofloxacin-induced lung injury is rare for its frequent prescription. Moreover, eye drops of it has never been reported to cause lung injury. We should be aware of eye drops as a causative dosage forms of drug-induced lung injury.

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A 51-year-old male patient was receiving treatment for Mycobacterium abscessus infection for approximately 10 years. However, as his condition gradually progressed to type II respiratory insufficiency, he was referred to our hospital, which was near his home. Computed tomography on his first visit revealed an abscess in the right lower lobe. Because respiratory insufficiency was evident, he was admitted the same day. We began treatment with meropenem, amikacin, and clarithromycin, but his symptoms did not improve. In accordance with the 2007 American Thoracic Society/Infectious Diseases Society of America statement, we administered linezolid, which resulted in gradual improvement in his physical status and imaging findings.

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The impermeability barrier provided by the outer membrane of enteric bacteria, a feature lacking in Gram-positive bacteria, plays a major role in maintaining resistance to numerous antimicrobial compounds and antibiotics. Here we demonstrate that mutational inactivation of spr, coding for a muramyl endopeptidase, significantly sensitizes Salmonella enterica serovar Typhimurium to vancomycin without any accompanying apparent growth defect or outer membrane destabilization. A similar phenotype was not achieved by deleting the genes coding for muramyl endopeptidases MepA, PbpG, NlpC, YedA, or YhdO. The spr mutant showed increased autolytic behavior in response to not only vancomycin, but also to penicillin G, an antibiotic for which the mutant displayed a wild-type MIC. A screen for suppressor mutations of the spr mutant phenotype revealed that deletion of tsp (prc), encoding a periplasmic carboxypeptidase involved in processing Spr and PBP3, restored intrinsic resistance to vancomycin and reversed the autolytic phenotype of the spr mutant. Our data suggest that Spr contributes to intrinsic antibiotic resistance in S. Typhimurium without directly affecting the outer membrane permeability barrier. Furthermore, our data suggests that compounds targeting specific cell wall endopeptidases might have the potential to expand the activity spectrum of traditional Gram-positive antibiotics.

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All-trans retinoic acid (atRA), the oxidative metabolite of retinoic acid (RA), is essential for palatogenesis. Overdose RA is capable of inducing cleft palate in mice and humans. Normal embryonic palatal mesenchymal (EPM) cell growth is crucial for shelf growth. Smad signaling is involved in many biological processes. However, it is not much clear if atRA could affect Smad signaling during EPM cells growth. In this study, the timed pregnant mice with maternal administration of 100 mg/kg body weight of RA by gastric intubation were cervical dislocation executed to evaluate growth changes of palatal shelves by hematoxylin and eosin (H&E) staining. At the same time, a primary mouse EPM (MEPM) cell culture model was also established. MEPM cells were treated with atRA (0.1, 0.5, 1, 5 and 10 µM) for 24, 48 and 72 h. The results indicated that the sizes of the shelves were smaller than those in control. AtRA inhibited MEPM cell growth with both increasing concentration and increasing incubation time, especially at 72 h in vitro. Moreover, atRA significantly increased the mRNA and protein expression levels of Smad7 (P < .05), but the mRNA and protein expression levels of PCNA were reduced (P < .05). We also found atRA inhibited phosphorylation of Smad2 compared with untreated group (P < .05). However, the protein and mRNA levels of Smad2 did not change both in atRA-treated and untreated group (P > .05). We demonstrated that RA induced inhibition of MEPM cell growth that could cause cleft palate partly by down-regulation of Smad pathway.

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Mesenchymal cell proliferation is one of the processes in shelf outgrowth. Both all-trans retinoic acid (atRA) and transforming growth factor-ß3 (TGF-ß3) play an important role in mouse embryonic palate mesenchymal (MEPM) cell proliferation. The cellular effects of TGF-ß are mediated by Smad-dependent or Smad-independent pathways. In the present study, we demonstrate that atRA promotes TGF-ß3 promoter demethylation and protein expression, but can cause depression of mesenchymal cell proliferation, especially at embryonic day 14 (E14). Moreover, the inhibition of MEPM cell proliferation by atRA results in the downregulation of Smad signaling mediated by transforming growth interacting factor (TGIF). We speculate that the effects of atRA on MEPM cell proliferation may be mediated by Smad pathways, which are regulated by TGIF but are not related to TGF-ß3 expression. Finally, the cellular effects of TGF-ß3 on MEPM cell proliferation may be mediated by Smad-independent pathways.

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Mesenchymal-cell proliferation is the main process in shelf outgrowth. Both all-trans-retinoic acid (atRA) and transforming growth factor-ß3 (TGF-ß3) play an important role in mouse embryonic palate mesenchymal (MEPM) cell proliferation. In the present study, we investigated the crosstalk between RA and TGF-ß signaling in MEPM-cell proliferation. We found that atRA inhibited MEPM-cell proliferation by downregulating TGF-ß/Smad signaling and that TGF-ß3 treatment was able to antagonize RA signaling. Transforming growth-interacting factor (TGIF) is a transcriptional repressor that suppresses both TGF-ß- and retinoid-driven gene transcription. Furthermore, we investigated the role of TGIF in the interaction between both TGF-ß and RA signaling in MEPM-cell proliferation. The results showed that both atRA and TGF-ß3 significantly increased the expression level of TGIF, and TGIF mediated the negative interaction between TGF-ß and RA signaling pathways, which depended on TGIF binding to Smad2 or RARß (RA receptor beta). Moreover, after deletion of TGIF, both the effects of atRA on TGF-ß-dependent protein expression and the effects of TGF-ß on RA-dependent protein expression were lost. So we conclude that there is a negative functional interplay of RA and TGF-ß signaling mediated by TGIF to modulate MEPM-cell proliferation.

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