Optical measurement of gating pore currents in hypokalemic periodic paralysis model cells

Hypokalemic periodic paralysis (HypoPP) is a rare genetic disease associated with mutations in CACNA1S or SCN4A, encoding Cav1.1 or Nav1.4, respectively. Most HypoPP-associated missense changes occur at the arginine residues within the voltage-sensing domain (VSD) of these channels. It is established that such mutations destroy the hydrophobic seal separating the external water and the internal cytosolic crevices, resulting in the generation of aberrant leak currents called gating pore currents. Presently, the gating pore currents are thought to underlie HypoPP. Here, we generated HEK293T-based HypoPP-model cell lines with the Sleeping Beauty transposon system that co-express mouse inward-rectifier potassium channel (mKir2.1) and HypoPP2-associated Nav1.4 variants. Whole cell patch-clamp measurements confirmed that mKir2.1 successfully hyperpolarized the membrane potential to comparable levels to myofibers, and that some Nav1.4 variants induced notable proton-based gating pore currents. Importantly, we succeeded in fluorometrically measuring the gating pore currents in these variants using a ratiometric pH indicator, SNARF-4F. Our optical method provides a potential in vitro platform for high-throughput drug screen, not only for HypoPP but also for other channelopathies caused by VSD mutations.Kubota T., Takahashi S., Yamamoto R., et al. Optical measurement of gating pore currents in hypokalemic periodic paralysis model cells. DMM Disease Models and Mechanisms 16, A18 (2023); https://doi.org/10.1242/dmm.049704

A Case of Metastatic Fumarate Hydratase-Deficient–like Renal Cell Carcinoma Successfully Managed by Ipilimumab plus Nivolumab

We report a 62-year-old male with metastatic fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) without fumarate hydratase (FH) mutation (FH-deficient–like RCC). The International Metastatic RCC Database Consortium risk score was intermediate, and immunotherapy with nivolumab and ipilimumab (Ipi/ Nivo) was initiated. Four cycles of Ipi/Nivo and 5 cycles of nivolumab resulted in a complete response of the metastases. Hypophysitis occurred as an immune-related adverse event after four cycles of Ipi/Nivo. The prognosis of patients with FH-deficient RCC is generally poor. Few reports of FH-deficient RCC successfully treated with Ipi/Nivo have been published. Ipi/Nivo can be effective for treating FH-deficient RCC

Robotic Renal Autotransplantation: First Case Outside of North America

A 38-year-old woman with a 2.7-cm left ureteral stenosis requiring chronic ureteral stent exchange elected to undergo robotic renal autotransplantation. Left ureteropelvic junction obstruction (UPJO) was also suspected. Robotic donor nephrectomy contributed to the fine dissection for desmoplastic changes. The kidney was removed through a Gelport and examined on ice. UPJO was not seen. An end-to-side robotic anastomosis was created between the renal and external iliac vessels. The console time was 507 min, and the warm ischemia time was 4 min 5 sec. She became stent-free. Robotic renal autotransplantation is a new, minimally invasive approach to renal preservation

Feasible kidney donation with living marginal donors, including diabetes mellitus

Objectives: To compare the donor outcomes of living donor kidney transplantation between standard donors (SDs) and marginal donors (MDs) including diabetic patients (MD + DM). Methods: MDs were defined according to Japanese guideline criteria: (a) age >70-years, (b) blood pressure 25 to = 70 to 6.2 or Results: No kidney function parameters were different between SDs and MDs. When comparing SD and MD + DM, MD + DM had a lower postoperative eGFR (48 vs. 41 (1 (month), p = .02), 49 vs. 40 (12, p = 2 risk factors. Conclusions: Although long-term observation of donor kidney function is necessary, careful MD + DM selection had the potential to expand the donor pool

ABO Blood Incompatibility Positively Affects Early Graft Function: Single-Center Retrospective Cohort Study

Background We investigated the association between ABO-incompatible (ABO-I) kidney transplantation and early graft function. Methods We retrospectively analyzed 95 patients who underwent living donor kidney transplantation between May 2009 and July 2019. It included 61 ABO-compatible (ABO-C) and 34 ABO-I transplantations. We extracted data on immunologic profile, sex, age, cold ischemic time, type of immunosuppression, and graft function. Two definitions were used for slow graft function (SGF) as follows: postoperative day (POD) 3 serum creatinine level >3 mg/dL and estimated glomerular filtration rate (eGFR) Results The characteristics between the ABO-C and ABO-I were not different. ABO-I received rituximab and plasma exchange. Patients also received tacrolimus and mycophenolate mofetil for 2 weeks and prednisolone for 1 week before transplantation as preconditioning. Of the 95 study patients, 19 (20%) and 21 (22%) were identified with SGF according to POD 3 serum creatinine level or eGFR, respectively. Multivariable analysis revealed that ABO-I significantly reduced the incidence of SGF (odds ratio, 0.15; 95% confidence interval, 0.03-0.7; P = .02), and cold ischemic time >150 min increased the incidence of SGF (odds ratio, 6.5; 95% confidence interval, 1.7-25; P = .006). Similar results were identified in POD 3 eGFR. Inferior graft function in patients with SGF was identified up to 6 months after transplantation. Conclusion ABO-I reduces the incidence of SGF, which is associated with an inferior graft function up to 6 months

Robotic Renal Autotransplantation: A Feasibility Study in a Porcine Model

We investigated the feasibility of robotic renal autotransplantation (RAT) in a porcine model to reduce invasiveness of RAT. Five pigs underwent robotic RAT using the da Vinci® robotic system. A robotic left nephrectomy was performed in all cases. Robotic RAT was performed on the left side in all but one case. Four ports were used. In 3 cases, the kidney was taken out through the GelPort® and irrigated on ice with Ringer’s solution. In 2 cases, a complete intracorporeal robotic RAT was performed. An end-to-side anastomosis was performed between the renal vein and the external iliac vein and between the renal artery and the external iliac artery. Ureteroneocystostomy was also performed in 2 cases. All cases were performed robotically without open conversion. The median (IQR) console time was 3.1 (0.7) h, and the operative time was 3.8 (1.1) h. The estimated blood loss was 30 (0) ml. The warm ischemia time was 4.0 (0.2) min, and the cold ischemia time was 97 (17) min. Intracorporeal transarterial hypothermic renal perfusion was feasible in the 2 complete intracorporeal robotic RAT cases by using a perfusion catheter through a laparoscopic port. Robotic RAT has the potential to be a new minimally invasive substitute for conventional open surgery

Combined Laparoscopic and CT Monitoring of the Ice-Ball Margin during Cryoablation for Renal Cell Carcinoma Associated with von Hippel-Lindau Disease: First Case

We report a 47-year-old Japanese female with 10 previous treatments for multiple bilateral renal cell carcinoma (RCC) associated with von Hippel-Lindau disease. The 14-mm right lower pole renal tumor was in contact with the right ureter. Laparoscopic cryoablation was performed to protect the ureter wrapped with gauze. Computed tomography (CT) monitoring was used to confirm the precise ≥ 6 mm ice-ball margin. There was no local progression at 6-months post-surgery. The serum creatinine has been stable. This is apparently the first report of combined laparoscopic and CT monitoring of an ice-ball formation and its margin during cryoablation for RCC

The Efficacy of Rituximab in High-risk Renal Transplant Recipients

Although graft survival following renal transplantation (RTx) has improved, outcomes following highrisk RTx are variable. Preexisting antibodies, including donor-specific antibodies (DSA), play an important role in graft dysfunction and survival. We have designed a study to investigate the safety and efficacy of anti-CD20 monoclonal antibodies (rituximab) in high-risk RTx recipients. Major eligibility criteria include: 1) major and minor ABO blood group mismatch, 2) positive DSA. Thirty-five patients will receive 200 mg/body of rituximab. The primary endpoint is the incidence of B cell depletion. This study will clarify whether rituximab is efficacious in improving graft survival in high-risk RTx recipients

Contrast-enhanced Computed Tomography-Guided Percutaneous Cryoablation of Renal Cell Carcinoma in a Renal Allograft: First Case in Asia

Nephron-sparing treatment should be offered whenever possible to avoid dialysis in allograph cases. Cryoablation is a new treatment option for treating small-sized renal cell cancer (RCCs). We report a case of RCC arising in a kidney allograft treated by cryoablation. To our knowledge, this is the first case in Asia of RCC in a renal allograft treated using cryoablation. Contrast-enhanced CT-guided percutaneous renal needle biopsy and cryoablation were used to identify the RCC, which could not be identified by other techniques. The postoperative course was uneventful. Contrast-enhanced CT also showed no recurrence or metastases at the 6-month follow-up