Structural features of T-DNA that induce transcriptional gene silencing during agroinfiltration.

Agrobacterium tumefaciens (Rhizobium radiobacter) is used for the transient expression of foreign genes by the agroinfiltration method, but the introduction of foreign genes often induces transcriptional and/or post-transcriptional gene silencing (TGS and/or PTGS). In this study, we characterized the structural features of T-DNA that induce TGS during agroinfiltration. When A. tumefaciens cells harboring an empty T-DNA plasmid containing the cauliflower mosaic virus (CaMV) 35S promoter were infiltrated into the leaves of Nicotiana benthamiana line 16c with a GFP gene over-expressed under the control of the same promoter, no small interfering RNAs (siRNAs) were derived from the GFP sequence. However, siRNAs derived from the CaMV 35S promoter were detected, indicating that TGS against the GFP gene was induced. When the GFP gene was inserted into the T-DNA plasmid, PTGS against the GFP gene was induced whereas TGS against the CaMV 35S promoter was suppressed. We also showed the importance of terminator sequences in T-DNA for gene silencing. Therefore, depending on the combination of promoter, terminator and coding sequences on T-DNA and the host nuclear genome, either or both TGS and/or PTGS could be induced by agroinfiltration. Furthermore, we showed the possible involvement of three siRNA-producing Dicers (DCL2, DCL3 and DCL4) in the induction of TGS by the co-agroinfiltration method. Especially, DCL2 was probably the most important among them in the initial step of TGS induction. These results are valuable for controlling gene expression by agroinfiltration.

Effect of sutureless securement on hemodialysis catheter-related bloodstream infection.

The use of sutureless securement devices during catheterization might reduce the risk of catheter-related bloodstream infection (CRBSI) by suppressing catheter-exit infection and catheter dislodgement. However, the effectiveness of these devices in reducing CRBSI risk when securing hemodialysis catheters has not been explored. This single-center retrospective observational study examined 211 non-tunneled hemodialysis catheters (NTHCs) from 110 hemodialysis inpatients, of which 121 were secured using conventional skin sutures (Suture group) and 90 with GRIP-LOK (GRIP-LOK group). The stabilized inverse probability of treatment (SIPT)-weighting method was used to generate a new population (SIPT-weighted model) without group differences for each of the 12 predictors of CRBSI development (i.e., age, sex, dialysis history, concomitant acute kidney injury or diabetes, concurrent use of immunosuppressant drugs or aspirin, NTHC insertion site, methicillin-resistant Staphylococcus aureus, carriage, bacteremia event within 3 months before catheterization, hemoglobin level, and serum albumin titer). The effect of GRIP-LOK compared with sutures on CRBSI in the SIPT-weighted model was evaluated using univariate SIPT-weighted Cox proportional regression analysis, which showed a significant CRBSI suppression effect of GRIP-LOK compared with sutures (hazard ratio: 0.17 [95% CI 0.04-0.78], p = 0.023).　GRIP-LOK affords a lower risk of CRBSI due to indwelling NTHCs than conventional securement using sutures.