Clostridium difficile infection (CDI) is principally responsible for hospital acquired, antibiotic-induced diarrhea and colitis and represents a significant financial burden on our healthcare system. Little is known about C. difficile proliferation requirements, and a better understanding of these parameters is critical for development of new therapeutic targets. In cell lines, C. difficile toxin B has been shown to inhibit Na(+)/H(+) exchanger 3 (NHE3) and loss of NHE3 in mice results in an altered intestinal environment coupled with a transformed gut microbiota composition. However, this has yet to be established in vivo in humans. We hypothesize that C. difficile toxin inhibits NHE3, resulting in alteration of the intestinal environment and gut microbiota. Our results demonstrate that CDI patient biopsy specimens have decreased NHE3 expression and CDI stool has elevated Na(+) and is more alkaline compared with stool from healthy individuals. CDI stool microbiota have increased Bacteroidetes and Proteobacteria and decreased Firmicutes phyla compared with healthy subjects. In vitro, C. difficile grows optimally in the presence of elevated Na(+) and alkaline pH, conditions that correlate to changes observed in CDI patients. To confirm that inhibition of NHE3 was specific to C. difficile, human intestinal organoids (HIOs) were injected with C. difficile or healthy and CDI stool supernatant. Injection of C. difficile and CDI stool decreased NHE3 mRNA and protein expression compared with healthy stool and control HIOs. Together these data demonstrate that C. difficile inhibits NHE3 in vivo, which creates an altered environment favored by C. difficile.
We report a facile, low-temperature reaction between condensed-phase NO 2 and H 2 O that leads ultimately to the formation of a large concentration (θ 0 ) 0.42 monolayers) of adsorbed oxygen adatoms on a Au(111) surface. This reaction represents a novel route to generate surface oxygen on Au that can be utilized in fundamental studies of oxidation catalysis over Au such as low-temperature CO oxidation and the operation of Au converter tubes used in redox chemiluminesence detectors for atmospheric NO x . Also, this reaction may be relevant to heterogeneous processes occurring on ice particles in stratospheric clouds. This reaction is not specifically catalyzed by the Au(111) surface or by the defects present on the Au surface, and so this reaction may have some general utility for facile oxidation of unreactive surfaces.
Canonical Wnt signaling is critical for the control of osteoblast differentiation in human mesenchymal stem cells. MicroRNAs (miRs) are essential regulators of cell differentiation by post‑transcriptional regulation of target gene expression. The aim of the present study was to investigate the molecular mechanism by which miR‑142‑3p promotes osteoblastic differentiation using the human fetal osteoblastic 1.19 (hFOB1.19), real-time PCR and western blot analysis. Results showed an increased expression of miR‑142‑3p during osteoblast differentiation in the mesenchymal precursor cell line, hFOB1.19. In addition, the ectopic over-expression of miR‑142‑3p promoted hFOB1.19 differentiation, whereas the inhibition of miR‑142‑3p repressed differentiation. The expression of miR‑142‑3p was positively correlated with β‑catenin, an important protein in Wnt signaling. The adenomatous polyposis coli (APC) gene was a direct target of miR‑142‑3p, whereby miR‑142‑3p promoted Wnt signaling through inhibition of APC, leading to accumulation and nuclear translocation of β‑catenin. Therefore, miR‑142‑3p may be an essential mediator of osteoblast differentiation and a new therapeutic strategy for osteogenesis disorders.
High dose melphalan followed by autologous stem cell transplantation remains standard of care for eligible patients with multiple myeloma, but disease response and toxicity, including severe mucositis, varies among patients. Our randomized trial investigated duration of cryotherapy (2 and 6 hours) for reduction of mucositis prevalence and severity and explored factors associated with variability in pharmacokinetics and outcomes from melphalan therapy. The results demonstrate 2-hour is at least as effective as 6-hour cryotherapy in decreasing severe mucositis. From a population pharmacokinetic model, we identified fat free mass, hematocrit, and creatinine clearance were significant covariates, as had been reported previously. Furthermore, we observed the rs4240803 SLC7A5 polymorphism was significantly associated with pharmacokinetic variability, and pharmacokinetics was associated with both mucositis and neutropenia. However, melphalan exposure was not associated with progression-free or overall survival in our dataset. These findings contribute to ongoing efforts to personalize melphalan dosing in transplant patients.
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