R-loops are formed when replicative forks collide with the transcriptional machinery and can cause genomic instability. However, it is unclear how R-loops are regulated at transcription-replication conflict (TRC) sites and how replisome proteins are regulated to prevent R-loop formation or mediate R-loop tolerance. Here, we report that ATAD5, a PCNA unloader, plays dual functions to reduce R-loops both under normal and replication stress conditions. ATAD5 interacts with RNA helicases such as DDX1, DDX5, DDX21 and DHX9 and increases the abundance of these helicases at replication forks to facilitate R-loop resolution. Depletion of ATAD5 or ATAD5-interacting RNA helicases consistently increases R-loops during the S phase and reduces the replication rate, both of which are enhanced by replication stress. In addition to R-loop resolution, ATAD5 prevents the generation of new R-loops behind the replication forks by unloading PCNA which, otherwise, accumulates and persists on DNA, causing a collision with the transcription machinery. Depletion of ATAD5 reduces transcription rates due to PCNA accumulation. Consistent with the role of ATAD5 and RNA helicases in maintaining genomic integrity by regulating R-loops, the corresponding genes were mutated or downregulated in several human tumors.

Although anterior approaches to the cervical spine are popular and safe, they cause some of complications. Esophageal perforation after anterior spinal fusion is a rare but potentially life-threatening complication. We present a rare case of delayed esophageal perforation caused by a cervical screw placed via the anterior approach. A 43-year-old man, who had undergone surgery for complete cord injury at another orthopedic department 8 years previously, was admitted to our institute due to painful neck swelling and dysphagia. Radiological studies revealed a protruding screw and esophageal perforation. The perforation was found during surgery and was successfully repaired. This case emphasizes the need for careful long-term follow-up to check for delayed esophageal perforation in patients that have undergone anterior cervical spine plating.

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Upon entering the human body, Vibrio vulnificus, a gram-negative marine bacterium, must withstand a temperature change (TC) from 25 to 37 °C. This bacterium acquires iron mainly via the vulnibactin receptor (VuuA)-mediated iron uptake system (IUS), which is under the positive control of cyclic AMP receptor protein (CRP), a global regulator responsible for catabolite repression. In this study, we examined the effect of TC on the expression of vuuA and crp, and the reciprocal relation between VuuA-mediated IUS and CRP under iron-limited conditions. Iron limitation increased vuuA expression but decreased crp expression. TC resulted in increased vuuA and crp expression. A crp or vuuA mutation reciprocally decreased vuuA or crp expression. TC could increase vuuA or crp expression even in a crp- or vuuA-mutated background. These results indicate that TC increases the expression of both vuuA and crp by facilitating metabolism under iron-limited conditions, and that CRP and VuuA-mediated IUS interact coordinately toward optimal metabolism in V. vulnificus.

Pseudomonas aeruginosa is an opportunistic pathogen which is frequently isolated from clinical specimens obtained from burns, surface wounds, the urinary tract, ear and eye infections, and the lungs of patients with cystic fibrosis. 1) P. aeruginosa secretes many extracellular proteins, and of these, several proteases including alkaline protease (AprA) and elastase (LasB) are known to play important roles in the pathogenesis of human infections caused by P. aeruginosa. 2,3)In response to iron deprivation, P. aeruginosa produces two unrelated siderophores, pyoverdin and pyochelin. Both of these siderophores promote the growth of P. aeruginosa when added to media containing transferrins as an iron source. Pyoverdin is considered to be the essential or more effective siderophore because of its higher iron-binding constant (pyoverdin 10 32 and pyochelin 10 5 ). Moreover, a pyochelin-deficient mutant was able to grow in human sera, whereas a pyoverdin-deficient mutant exhibited severely retarded growth, and the addition of pyoverdin was found to restore the retarded growth of pyoverdin-deficient mutants in media containing transferrins. [4][5][6] P. aeruginosa produces several extracellular proteases. Of these, AprA and LasB have been extensively studied. [7][8][9] These two proteases are produced more profoundly in irondeficient conditions than in iron-sufficient conditions, and are able to destroy transferrin, which is a major iron-withholding protein in human body fluids. Because of the high affinity of transferrin for iron, transferrin-bound iron is not freely-available for P. aeruginosa growth. Accordingly, the proteolytic cleavage of transferrin can allow free iron to be released from transferrin, and thus facilitate the pyoverdin-mediated iron-uptake and growth of P. aeruginosa.However, this hypothesis still remains unresolved despite considerable efforts. Some researchers have reported that LasB facilitates pyoverdin-mediated iron-uptake via the proteolytic cleavage of transferrins, 3,7) but others found that LasB had no effect on the iron-uptake from transferrins because no difference was observed between the growths of a LasB-deficient mutant and its wild type strain and LasB was produced after the onset of stationary growth phase in media containing transferrin as an iron source. 9) Similarly, Döring et al. 7) found that AprA had no effect on pyoverdin-mediated iron-uptake from transferrins, but Shigematsu et al.8) more recently reported that AprA can facilitate siderophore-mediated iron-uptake via the proteolytic cleavage of transferrins.Although Shigematsu et al. observed that the growth of an aprA-insertion mutant was suppressed in media containing transferrins versus the wild type strain, they did not directly observe whether the AprA produced during culture could destroy transferrins.8) Rather, they exogenously added purified AprA to culture media in order to induce the proteolytic cleavage of transferrins at culture start. As the aprA-insertional mutation may also cause unexpected changes in the p...

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Self-expandable metal stent (SEMS) placement is commonly used for palliation of left-sided malignant colorectal obstruction (MCO). However, right-sided MCO is usually treated surgically. Recent studies that compared palliative SEMS insertion and emergency surgery in right-sided MCOs have reported conflicting results. This study aimed to compare the effectiveness of palliative SEMS placement in left-sided MCOs and right-sided MCOs and to investigate the predictive factors for clinical success and risk factors for complications. Data from 469 patients who underwent palliative SEMS placement for MCO at 6 hospitals in the Honam province of South Korea between 2009 and 2018 were reviewed. Among them, 69 patients with right-sided MCO and 400 patients with left-sided MCO who underwent SEMS placement for palliative purposes were enrolled. Clinical success, overall survival, complications, and predictive factors for clinical success and risk factors for complications were included as the main outcome measures. The clinical success rates were 97.1% (65/67) in right-sided MCO patients and 88.2% (353/400) in left-sided MCO patients. Complications including stent migration, tumor ingrowth, outgrowth, perforation, bacteremia/fever, and bleeding occurred in 10.1% (7/69) of right-sided MCO patients and 19.9% (79/400) of left-sided MCO patients. The mean overall survival of right-sided MCO was 28.02 months and 18.23 months for left-sided MCO. In multivariate logistic regression analysis, T3 stage tumors and the use of uncovered stents were significant factors for the clinical success of SEMS. The use of covered stents and performance status score of 0 to 2 were independent significant risk factors for complications. Palliative SEMS placement in right-sided MCO showed better clinical success rates than left-sided MCO. The use of uncovered stents is recommended for higher clinical success rates and lower complication rates.

The ferrophilic bacterium Vibrio vulnificus can utilize the siderophore aerobactin of Escherichia coli for iron acquisition via its specific receptor IutA. This siderophore piracy by V. vulnificus may contribute to its survival and proliferation, especially in mixed bacterial environments. In this study, we examined the effects of glucose, cyclic AMP (cAMP), and cAMP-receptor protein (Crp) on iutA expression in V. vulnificus. Glucose dose-dependently repressed iutA expression. A mutation in cya encoding adenylate cyclase required for cAMP synthesis severely repressed iutA expression, and this change was recovered by in trans complementing cya or the addition of exogenous cAMP. Furthermore, a mutation in crp encoding Crp severely repressed iutA expression, and this change was recovered by complementing crp. Accordingly, glucose deprivation under iron-limited conditions is an environmental signal for iutA expression, and Crp functions as an activator that regulates iutA expression in response to glucose availability.