Allograft Vesicoureteral Reflux after Kidney Transplantation

Allograft vesicoureteral reflux (VUR) is a leading urological complication of kidney transplantation. Despite the relatively high incidence, there is a lack of consensus regarding VUR risk factors, impact on renal function, and management. Dialysis vintage and atrophic bladder have been recognized as the most relevant recipient-related determinants of post-transplant VUR, whilst possible relationships with sex, age, and ureteral implantation technique remain debated. Clinical manifestations vary from an asymptomatic condition to persistent or recurrent urinary tract infections (UTIs). Voiding cystourethrography is widely accepted as the gold standard diagnostic modality, and the reflux is generally graded following the International Reflux Study Committee Scale. Long-term transplant outcomes of recipients with asymptomatic grade I-III VUR are yet to be clarified. On the contrary, available data suggest that symptomatic grade IV-V VUR may lead to progressive allograft dysfunction and premature transplant loss. Therapeutic options include watchful waiting, prolonged antibiotic suppression, sub-mucosal endoscopic injection of dextranomer/hyaluronic acid copolymer at the site of the ureteral anastomosis, and surgery. Indication for specific treatments depends on recipient’s characteristics (age, frailty, compliance with antibiotics), renal function (serum creatinine concentration < 2.5 vs. ≥ 2.5 mg/dL), severity of UTIs, and VUR grading (grade I-III vs. IV-V). Current evidence supporting surgical referral over more conservative strategies is weak. Therefore, a tailored approach should be preferred. Properly designed studies, with adequate sample size and follow-up, are warranted to clarify those unresolved issues.

Predictors of Conduction Disturbances after Transcatheter Aortic Valve Implantation with Balloon-expandable Valve for Bicuspid Aortic Valve Stenosis

Objective: The implantation depth and membranous septum (MS) length are established as the predictors of new-onset conduction disturbance (CD) after transcatheter aortic valve replacement (TAVR) for tricuspid aortic valve (TAV) stenosis. However, little is known about the predictors with bicuspid aortic valve (BAV). This study investigated the role of MS length and implantation depth in predicting CD following TAVR with a balloon-expandable valve in patients with BAV. Methods and results: This retrospective study analyzed 169 patients who underwent TAVR for BAV with balloon-expandable valve, and TAV cohort was established as a control group using propensity score (PS) matching. The primary endpoint was in-hospital new-onset CD (new-onset left bundle branch block or new permanent pacemaker implantation). New-onset CD developed in 37 patients (21.9%). Multivariate analysis revealed severe LVOT calcification (Odds ratio [OR]: 5.83, 95% confidence interval [CI]: 1.08 – 31.5, p = 0.0407) and implantation depth – MS length (OR: 1.30, 95% CI: 1.12 – 1.51, p = 0.0005) as the predictors of new-onset CD within BAV cohort. The matched comparison between BAV and TAV groups showed similar MS length (3.0 vs 3.2mm, p = 0.5307), but valves were implanted deeper in BAV than TAV group (3.9 vs 3.0mm, p < .0001). New-onset CD was more frequent in patients having BAV (22.3% vs 13.9%, p = 0.0458). Conclusion: The implantation depth - MS length, and severe LVOT calcification predicted new-onset CD following TAVR in BAV with balloon-expandable valve. High implantation technique could be considered to avoid new-onset CD in BAV anatomy.

299 3-Year results of STEMI patients treated with a pre-specified BVS implantation strategy: BVS SYTEMI strategy-it long term

Aims Data on Absorb bioresorbable vascular scaffold (BVS) use in patients presenting with ST-segment elevation myocardial infarction (STEMI) are limited. Furthermore, Absorb studies including STEMI patients lacked a prespecified implantation technique to optimize BVS deployment. To assess the 3-year clinical outcomes STEMI patients undergoing primary percutaneous coronary intervention (pPCI) with a pre-specified BVS implantation strategy. Methods and results BVS STEMI STRATEGY-IT (NCT02601781) included 505 STEMI patients undergoing pPCI with BVS following a dedicated implantation protocol. Device-oriented composite endpoint [(DOCE) cardiac death, ischemia-driven target lesion revascularization (ID-TLR) and target vessel myocardial infarction (TV-MI)] and scaffold thrombosis (ScT) at 3-year were evaluated. A subgroup analysis was performed on patients in whom dual antiplatelet therapy (DAPT) was continued 36 months after pPCI (‘longer-term DAPT’), and outcomes of this cohort compared to the remaining population (‘shorter-term DAPT’: &lt;36 months) are also reported. Three-year DOCE and ScT rates were low (2.4% and 1.0%, respectively). In 319 (63.2%) patients DAPT was continued 36 months after pPCI. DOCE rate was significantly lower in the longer- compared to shorter-DAPT group (HR: 0.29; 95% CI: 0.1–0.9; P = 0.03), driven by a lower rate of TV-MI (0% vs. 2.2%, P = 0.018). Significantly lower rate of ScT was observed in longer-DAPT group (0% vs. 2.7%, P = 0.007). Conclusions In STEMI patients undergoing pPCI, a strategy of optimized BVS implantation technique is associated with favourable DOCE and ScT rates at 3 year. DAPT extension up to 36 months further improves long-term clinical outcomes.

Physical mechanism for photon emissions from group-IV-semiconductor quantum-dots in quartz-glass and thermal-oxide layers

We experimentally studied the influence of both impurity density and dangling-bond density on PL emissions from group-IV-semiconductor quantum-dots (IV-QDs) of Si and SiC fabricated by hot-ion implantation technique, to improve the PL intensity (IPL) from IV-QDs embedded in two types of insulators of quartz glass (QZ) with low impurity density and thermal-oxide (OX) layers. First, we verified the IPL reduction in the IV-QDs in QZ. However, we demonstrated the IPL enhancement of IV-QDs in doped QZ, which is attributable to multiple-level emission owing to acceptor and donor ion implantations into QZ. Secondly, we confirmed the large IPL enhancement of IV-QDs in QZ and OX, owing to forming gas annealing with H2/N2 mixed gas, which are attributable to the reduction of the dangling-bond density in IV-QDs. Consequently, it is possible to improve the IPL of IV-QDs by increasing impurity density and reducing dangling-bond density.

A Novel Nitrogen Ion Implantation Technique for Turning Thin Film “Normally On” AlGaN/GaN Transistor into “Normally Off” Using TCAD Simulation

This study presents an innovative, low-cost, mass-manufacturable ion implantation technique for converting thin film normally on AlGaN/GaN devices into normally off ones. Through TCAD (Technology Computer-Aided Design) simulations, we converted a calibrated normally on transistor into a normally off AlGaN/GaN transistor grown on a silicon <111> substrate using a nitrogen ion implantation energy of 300 keV, which shifted the bandgap from below to above the Fermi level. In addition, the threshold voltage (Vth) was adjusted by altering the nitrogen ion implantation dose. The normally off AlGaN/GaN device exhibited a breakdown voltage of 127.4 V at room temperature because of impact ionization, which showed a positive temperature coefficient of 3 × 10−3 K−1. In this study, the normally off AlGaN/GaN device exhibited an average drain current gain of 45.3%, which was confirmed through an analysis of transfer characteristics by changing the gate-to-source ramping. Accordingly, the proposed technique enabled the successful simulation of a 100-µm-wide device that can generate a saturation drain current of 1.4 A/mm at a gate-to-source voltage of 4 V, with a mobility of 1487 cm2V−1s−1. The advantages of the proposed technique are summarized herein in terms of processing and performance.