Christopher Nguan

Loss of clusterin expression worsens renal ischemia-reperfusion injury

Prevention of ischemia-reperfusion injury (IRI) is a challenge in clinical care of the patients with kidney transplants or acute kidney injury, and understanding of the intrinsic mechanisms of resistance to injury in the kidney will lead to a novel therapy. Clusterin, a secreted glycoprotein, is an antiapoptotic protein in cancer cells. Our study is to investigate the role of clusterin in renal IRI. Renal IRI in mice was induced by clamping renal vein and artery for 45 or 50 min at 32 degrees C. Apoptosis of renal tubular epithelial cells (TECs) was determined by FACS analysis. Clusterin expression was examined by Western blot or immunohistochemistry. Here, we showed that clusterin protein was induced in TECs following IRI, and more tubules expressed clusterin in the kidneys following ischemia at higher temperatures. In human proximal TEC HKC-8 cultures, clusterin was upregulated by removal of serum and growth factors in medium and was downregulated by TNF-alpha-IFN-gamma mixture. The levels of clusterin were positively correlated with cell survival in these conditions. Knockdown or knockout of clusterin expression enhanced the sensitivity of TECs to apoptosis. In experimental models of renal IRI, deficiency in clusterin expression worsened the injury, as indicated by a significant increase in renal tissue damage with higher levels of serum creatinine and blood urea nitrogen and by a poorer recovery from the injury in clusterin-deficient mice compared with wild-type mice. Our data indicate that the reduction of inducible expression of clusterin results in an increase in TEC apoptosis in the cultures and renders mice susceptibility to IRI, implying a protective role of clusterin in kidney injury.

Prospective comparison of magnetic resonance angiography with selective renal angiography for living kidney donor assessment.

OBJECTIVESnFor years, the reference standard in the evaluation of living donor vascular anatomy has been selective renal angiography (SRA). Because of the potential morbidity associated with SRA, we prospectively evaluated magnetic resonance angiography (MRA) in the assessment of renal donors.nnnMETHODSnAll patients had SRA and 53 renal units were prospectively evaluated by MRA. We used SRA supplemented by findings at donor nephrectomy (DN) as our standard. We defined a positive test as the detection of any abnormality in the number of renal arteries.nnnRESULTSnSelective renal angiography yielded a sensitivity of 86%, specificity of 95%, positive predictive value (PPV) of 75%, and negative predictive value (NPV) of 97% compared with findings at DN. MRA had a sensitivity of 64%, 88% specificity, 58% PPV, and 90% NPV. MRA correctly identified only 7 of 11 renal units with accessory arteries. MRA also incorrectly identified 5 accessory arteries not present on SRA or DN. Two patients diagnosed with fibromuscular dysplasia by SRA were missed using MRA.nnnCONCLUSIONSnWe have shown that MRA is not capable of replacing SRA as the reference standard in renal donor imaging.

Robotic surgery versus laparoscopy; a comparison between two robotic systems and laparoscopy

Laparoscopy has found a role in standard urologic practice, and with training programs continuing to increase emphasis on its use, the division between skill sets of established non-laparoscopic urologic practitioners and urology trainees continues to widen. At the other end of the spectrum, as technology progresses apace, advanced laparoscopists continue to question the role of surgical robotics in urologic practice, citing a lack of significant advantage to this modality over conventional laparoscopy. We seek to compare two robotic systems (Zeus and DaVinci) versus conventional laparoscopy in surgical training modules in the drylab environment in the context of varying levels of surgical expertise. A total of 12 volunteers were recruited to the study: four staff, four postgraduate trainees, and four medical student interns. Each volunteer performed repeated time trials of standardized tasks consisting of suturing and knot tying using each of the three platforms: DaVinci, Zeus and conventional laparoscopy. Task times and numbers of errors were recorded for each task. Following each platform trial, a standardized subjective ten-point Likert score questionnaire was distributed to the volunteer regarding various operating parameters experienced including: visualization, fluidity, efficacy, precision, dexterity, tremor, tactile feedback, and coordination. Task translation from laparoscopy to Zeus robotics appeared to be difficult as both suture times and knot-tying times increased in pairwise comparisons across skill levels.

Extracapsular versus intracapsular allograft nephrectomy: impact on allosensitization and surgical outcomes

INTRODUCTIONnOur objective was to compare the impact of extra-capsular (ECAN) versus intracapsular allograft nephrectomy (ICAN) on allosensitization and surgical outcomes.nnnMETHODSnBetween 1990 and 2004, 96 allograft nephrectomies were performed at our institution. Of these, 29 procedures were performed within 1 month of the transplant and were therefore omitted from analysis. Overall, the results of 44 ECAN and 23 ICAN were reviewed.nnnRESULTSnThe mean operative times were 110.9 versus 130.4 min for ICAN versus ECAN (p = 0.02) and the estimated blood loss was 226 mL for ICAN versus 483 mL for ECAN (p = 0.004). Intraoperative and postoperative complications were low using either technique and differences were not statistically significant. Overall, the preoperative to postoperative change in the percentage of panel reactive antibody was +2.1% for ICAN versus +1.2% for ECAN (NS) at 3 to 12 months postoperatively, respectively (NS). The percentage of patients relisted was 33.3% versus 54.3% (NS), and the percentage of patients re-transplanted once relisted was also very similar: 63.2% for ECAN versus 66.7% for ICAN (NS), after a mean follow-up of 4.5 and 8.4 years, respectively.nnnCONCLUSIONSnICAN can be performed with shorter operative times and less blood loss versus the extracapsular approach. As well, this operative approach does not appear to affect allosensitization and the ability to re-transplant patients.

Robot-Assisted Pyeloplasty: Follow-Up of First Canadian Experience with Comparison of Outcomes Between Experienced and Trainee Surgeons

BACKGROUND AND PURPOSEnRobot-assisted pyeloplasty (RAP) has been established recently as an option in the management of ureteropelvic junction obstruction (UPJO). We present the first Canadian experience with RAP with respect to operative results and outcomes. We compare the surgical outcomes between experienced and trainee surgeons, with respect to operating room times and success rates.nnnPATIENTS AND METHODSnEighty-eight patients underwent transperitoneal RAP for UPJO using the da Vinci robotic platform. Two surgeons performed Anderson-Hynes dismembered pyeloplasty in 85 cases and YV-plasty in 5 cases. Five patients had RAP for secondary UPJO after failure of other treatments. Diuretic renography was performed at 6 weeks, and 6, 12, 18, 24, and 36 months postpyeloplasty. The mean follow-up was 14.1 ± 8.5 months.nnnRESULTSnThe mean operative time was 167.7 ± 43.2 minutes, and the mean anastomotic time was 41.9 ± 14.1 minutes. The mean operative duration significantly decreased with time (P < 0.05). Ten patients needed simultaneous nephroscopic stone management via the pyelotomy incision. The mean blood loss was 56.6 ± 55.4 mL, and the mean hospital stay was 2.5 ± 0.5 days. There were five major postoperative (stent migration, urinoma) and three minor complications that were associated with the RAP procedures. Postoperative renal scintigraphy demonstrated only four cases with persistent obstruction. Eighty-three (94.3%) patients experienced improvement of symptoms whereas 5 continued to be symptomatic. Two patients needed secondary procedures to relieve persisting obstruction. There were no statistical differences in outcomes between the experienced surgeons and trainees (P = 0.28).nnnCONCLUSIONSnIn the first large case series of RAP from Canada, we demonstrate that RAP can be performed with relatively short operative times and is safe and effective, achieving similar long-term results with standard open repair. We show that robot-assisted surgery can be safely transitioned to surgical trainees. With its cost and availability, its role in the Canadian system needs further study.

Prolonged renal allograft survival by donor interleukin-6 deficiency: association with decreased alloantibodies and increased intragraft T regulatory cells

Both humoral and cellular immune responses are involved in renal allograft rejection. Interleukin (IL)-6 is a regulatory cytokine for both B and Foxp3 (forkhead box P3)-expressing regulatory T (Treg) cells. This study was designed to investigate the impact of donor IL-6 production on renal allograft survival. Donor kidneys from IL-6 knockout (KO) vs. wild-type (WT) C57BL/6 mice (H-2(b)) were orthotopically transplanted to nephrotomized BALB/c mice (H-2(d)). Alloantibodies and Treg cells were examined by fluorescence-activated cell sorting analysis. Graft survival was determined by the time to graft failure. Here, we showed that a deficiency in IL-6 expression in donor kidneys significantly prolonged renal allograft survival compared with WT controls. IL-6 protein was upregulated in renal tubules and endothelium of renal allografts following rejection, which correlated with an increase in serum IL-6 compared with that in those receiving KO grafts or naive controls. The absence of graft-producing IL-6 or lower levels of serum IL-6 in the recipients receiving IL-6 KO allografts was associated with decreased circulating anti-graft alloantibodies and increased the percentage of intragraft CD4(+)CD25(+)Foxp3(+) Treg cells compared with those with WT allografts. In conclusion, the lack of graft-producing IL-6 significantly prolongs renal allograft survival, which is associated with reduced alloantibody production and/or increased intragraft Treg cell population, implying that targeting donor IL-6 may effectively prevent both humoral and cellular rejection of kidney transplants.

Reduction of chronic allograft nephropathy by inhibition of extracellular signal-regulated kinase 1 and 2 signaling

Chronic allograft nephropathy (CAN), the most common cause of late kidney allograft failure, is not effectively prevented by immunosuppressive regimens. Activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) via MEK mediates actions of various growth factors, including transforming growth factor (TGF)-beta1, which plays a key role in CAN. Hence, we tested the therapeutic potential of MEK-ERK1/2 signaling disruption to prevent CAN. Kidneys from C57BL/6J (H-2(b)) mice were transplanted to bilaterally nephrectomized BALB/c (H-2(d)) mice. At 14 days after transplantation, the recipients were subjected to 28 days of treatment with the MEK inhibitor CI-1040. All six CI-1040-treated allografts survived, while two of seven grafts in the vehicle-treated group were lost. At the end of the experiment, the function and structure of grafts in the CI-1040-treated group were significantly preserved, as indicated by lower levels of serum creatinine or blood urea nitrogen than in the vehicle-treated group [30 +/- 6 vs. 94 +/- 39 microM creatinine (P = 0.0015) and 22 +/- 8 vs. 56 +/- 25 mM BUN (P = 0.0054)] and reduced CAN in the CI-1040-treated group compared with vehicle controls (CAN score = 4.2 vs. 10.3, P = 0.0119). The beneficial effects induced by CI-1040 were associated with reduction of ERK1/2 phosphorylation and TGFbeta1 levels in grafts. Also, CI-1040 potently suppressed not only TGFbeta biosynthesis in kidney cell cultures but also antiallograft immune responses in vitro and in vivo. Our data suggest that interference of MEK-ERK1/2 signaling with a pharmacological agent (e.g., CI-1040) has therapeutic potential to prevent CAN in kidney transplantation.

Late renal vein aneurysm following living related renal transplant

Renal vein aneurysms are rare; there are less than 10 reported cases. As of yet there have been no reported cases of renal vein aneurysm following renal transplantation. We present a case of an incidentally discovered renal vein aneurysm following uncomplicated living related renal transplant. The lesion was discovered 4 years after the transplant through abdominal ultrasound investigation of new right lower quadrant discomfort. Magnetic resonance imaging confirmed the presence of a 2.3-cm thrombosed renal vein aneurysm of the main renal vein. This case report highlights the rare nature of these events, the diagnostic challenges and the lack of satisfactory management guidelines in these cases.