Gyrase inhibitors induce an oxidative damage cellular death pathway in Escherichia coli

Modulation of bacterial chromosomal supercoiling is a function of DNA gyrase-catalyzed strand breakage and rejoining. This reaction is exploited by both antibiotic and proteic gyrase inhibitors, which trap the gyrase molecule at the DNA cleavage stage. Owing to this interaction, double-stranded DNA breaks are introduced and replication machinery is arrested at blocked replication forks. This immediately results in bacteriostasis and ultimately induces cell death. Here we demonstrate, through a series of phenotypic and gene expression analyses, that superoxide and hydroxyl radical oxidative species are generated following gyrase poisoning and play an important role in cell killing by gyrase inhibitors. We show that superoxide-mediated oxidation of iron–sulfur clusters promotes a breakdown of iron regulatory dynamics; in turn, iron misregulation drives the generation of highly destructive hydroxyl radicals via the Fenton reaction. Importantly, our data reveal that blockage of hydroxyl radical formation increases the survival of gyrase-poisoned cells. Together, this series of biochemical reactions appears to compose a maladaptive response, that serves to amplify the primary effect of gyrase inhibition by oxidatively damaging DNA, proteins and lipids

Clinical characteristics, management strategies and outcomes of patients with recurrent venous thromboembolism in the real world

There is a paucity of data on management strategies and clinical outcomes after recurrent venous thromboembolism (VTE). In a multicenter registry enrolling 3027 patients with acute symptomatic VTE, the current study population was divided into the following 3 groups: (1) First recurrent VTE during anticoagulation therapy (N = 110); (2) First recurrent VTE after discontinuation of anticoagulation therapy (N = 116); and (3) No recurrent VTE (N = 2801). Patients with first recurrent VTE during anticoagulation therapy more often had active cancer (45, 25 and 22%, P < 0.001). Among 110 patients with first recurrent VTE during anticoagulation therapy, 84 patients (76%) received warfarin at recurrent VTE with the median prothrombin time-international normalized ratio (PT-INR) value at recurrent VTE of 1.6, although patients with active cancer had a significantly higher median PT-INR value at recurrent VTE compared with those without active cancer (2.0 versus 1.4, P < 0.001). Within 90 days after recurrent VTE, 23 patients (20.9%) during anticoagulation therapy and 24 patients (20.7%) after discontinuation of anticoagulation therapy died. Active cancer was a major cause of recurrent VTE during anticoagulation therapy as a patient-related factor, while sub-optimal intensity of anticoagulation therapy was a major cause of recurrent VTE during anticoagulation therapy as a treatment-related factor, particularly in patients without active cancer

Arabidopsis RPT2a, 19S Proteasome Subunit, Regulates Gene Silencing via DNA Methylation

The ubiquitin/proteasome pathway plays a crucial role in many biological processes. Here we report a novel role for the Arabidopsis 19S proteasome subunit RPT2a in regulating gene activity at the transcriptional level via DNA methylation. Knockout mutation of the RPT2a gene did not alter global protein levels; however, the transcriptional activities of reporter transgenes were severely reduced compared to those in the wild type. This transcriptional gene silencing (TGS) was observed for transgenes under control of either the constitutive CaMV 35S promoter or the cold-inducible RD29A promoter. Bisulfite sequencing analysis revealed that both the transgene and endogenous RD29A promoter regions were hypermethylated at CG and non-CG contexts in the rpt2a mutant. Moreover, the TGS of transgenes driven by the CaMV 35S promoters was released by treatment with the DNA methylation inhibitor 5-aza-2′-deoxycytidine, but not by application of the inhibitor of histone deacetylase Trichostatin A. Genetic crosses with the DNA methyltransferase met1 single or drm1drm2cmt3 triple mutants also resulted in a release of CaMV 35S transgene TGS in the rpt2a mutant background. Increased methylation was also found at transposon sequences, suggesting that the 19S proteasome containing AtRPT2a negatively regulates TGS at transgenes and at specific endogenous genes through DNA methylation

Variability of fractional flow reserve according to the methods of hyperemia induction

Objectives We performed this study to evaluate the variability of fractional flow reserve (FFR) values which were measured from various methods of hyperemia induction. Background Concerns have been raised regarding the variability of FFR due to different routes for hyperemic agent administration and different hyperemic agents targeting different receptors to induce maximal hyperemia. Methods A total of 656 intermediate coronary lesions from 628 patients with coronary artery disease were analyzed. Among them, 238 lesions underwent FFR measurement with hyperemia induced by both intravenous (IV) and intracoronary (IC) adenosine administration, 318 by IV adenosine/adenosine triphosphate (ATP) and IC nicorandil injection, and 100 by IV adenosine and regadenoson infusion. Results Excellent correlation and close classification agreement (FFR ≤ 0.80) were observed between IV vs. IC adenosine (r = 0.980, CA = 92.9%, Cohen's Kappa = 0.887, P < 0.001), between IV adenosine/ATP vs. IC nicorandil (r = 0.962, CA = 91.2%, Cohen's Kappa = 0.817, P < 0.001), and between IV adenosine vs. regadenoson (r = 0.990, CA = 100%, Cohen's Kappa = 1.000, P < 0.001). When changes in blood pressure (ΔBP) or heart rate (ΔHR) were compared with changes in FFR (ΔFFR) between IV adenosine/ATP and IC nicorandil administration, there were no significant correlations between ΔBP and ΔFFR nor between ΔHR and ΔFFR (r = -0.122, P = 0.076; r = 0.036, P = 0.605, respectively). Conclusions This study suggests that the measurement of FFR is reproducible regardless of the hemodynamic changes, hyperemic agents used, or the route of administration

Variability of fractional flow reserve according to the methods of hyperemia induction

\u3cp\u3eObjectives We performed this study to evaluate the variability of fractional flow reserve (FFR) values which were measured from various methods of hyperemia induction. Background Concerns have been raised regarding the variability of FFR due to different routes for hyperemic agent administration and different hyperemic agents targeting different receptors to induce maximal hyperemia. Methods A total of 656 intermediate coronary lesions from 628 patients with coronary artery disease were analyzed. Among them, 238 lesions underwent FFR measurement with hyperemia induced by both intravenous (IV) and intracoronary (IC) adenosine administration, 318 by IV adenosine/adenosine triphosphate (ATP) and IC nicorandil injection, and 100 by IV adenosine and regadenoson infusion. Results Excellent correlation and close classification agreement (FFR ≤ 0.80) were observed between IV vs. IC adenosine (r = 0.980, CA = 92.9%, Cohen's Kappa = 0.887, P &lt; 0.001), between IV adenosine/ATP vs. IC nicorandil (r = 0.962, CA = 91.2%, Cohen's Kappa = 0.817, P &lt; 0.001), and between IV adenosine vs. regadenoson (r = 0.990, CA = 100%, Cohen's Kappa = 1.000, P &lt; 0.001). When changes in blood pressure (ΔBP) or heart rate (ΔHR) were compared with changes in FFR (ΔFFR) between IV adenosine/ATP and IC nicorandil administration, there were no significant correlations between ΔBP and ΔFFR nor between ΔHR and ΔFFR (r = -0.122, P = 0.076; r = 0.036, P = 0.605, respectively). Conclusions This study suggests that the measurement of FFR is reproducible regardless of the hemodynamic changes, hyperemic agents used, or the route of administration.\u3c/p\u3