Characteristics of renal papillae in kidney stone formers

The mechanism of kidney stone formation is not well understood. In order to better understand the pathophysiology for specific kidney stone compositions and systemic diseases associated with kidney stones, endoscopic papillary mapping studies with concurrent biopsies have been conducted. This review will summarize the findings of these studies and proposed mechanisms for thirteen disease processes associated with kidney stones. A review of the literature was performed identifying thirteen studies that endoscopically mapped and biopsied renal papillae of different stone formers. These studies characterized renal papillae based on amount of Randall's plaque, Bellini's duct pathology, papillary contour changes, presence of attached stones, pitting, and frequently papillary and cortical biopsies. The groups studied and reviewed here are kidney stone formers who have a history of idiopathic calcium oxalate stone formation, cystinuria, brushite stones, gastric bypass, ileostomy, small bowel resection, primary hyperparathyroidism, distal renal tubular acidosis (dRTA), primary hyperoxaluria, idiopathic calcium phosphate stone formation, medullary sponge kidney (MSK), uric acid stones, and struvite stones. A proposed standardized scoring system for papillary pathology was also reviewed. The series showed various degrees and types of changes to the renal papillae and corresponding histopathologic changes for each type of stone former reviewed. Those with predominantly alone Randall's plaque pathology had less tissue damage versus those with extensive Bellini's duct lesions who had more interstitial fibrosis and cortical pathology. Randall's plaques are associated with stone formers who have low urinary volume, high urinary calcium, and acidic urine and thus are frequently seen in those with brushite stones, primary hyperparathyroidism, small bowel resection, and idiopathic calcium phosphate stone formers. Bellini's duct plugging and pathology is theorized to occur via free solution crystallization, ductal obstruction, inflammation, cellular injury, fibrosis, and acidification defects. Ureteroscopic manifestations of stone disease can vary from normal appearing papillae to significantly diseased appearing papillae. Some diseases have very characteristic papillary changes. Further studies are necessary to fully elucidate the mechanisms of stone formation in patients with nephrolithiasis.

Use of Contrasted Computerized Tomography as a Surrogate for Nuclear Medicine Renogram to Categorize Renal Function in the Setting of Ureteropelvic Junction Obstruction

OBJECTIVE

To use basic measurements on contrasted computerized tomography (CT) to reliably determine whether a kidney with ureteropelvic junction obstruction (UPJO) is definitively functional (≥30% differential renal function [DRF]) or nonfunctional (≤10% DRF), obviating the need for nuclear medicine renogram (RG) to determine DRF.

METHODS

This is a single institution, retrospective cohort of patients diagnosed with UPJO who underwent either pyeloplasty or nephrectomy between December 2004 and December 2014. Included patients had both preoperative mercaptoacetyltriglycine RG and contrasted CT within 180 days of each other. Patients with stents or nephrostomy tubes were excluded.

RESULTS

A total of 49 patients were included. The strongest correlation between differential CT measurements and DRF on RG existed by multiplying the cortical area by the average cortical Hounsfield units (Pearson's r = 0.90, P < .001). Using an equation derived from linear regression and cutoff values generated by receiver operator curve (ROC) analysis, CT equation-estimated DRF values of ≥40% and ≤10% correlated with "definitively functional" RG values of ≥30% (100% specificity) and with "definitively nonfunctional" RG values of ≤10% (100% specificity), respectively. In 30 out of 49 cases, CT could have replaced RG.

CONCLUSION

RG is the gold standard in determining quantitative DRF. However, the treatment algorithm for a kidney with symptomatic UPJO hinges on categorized function: "functional" (repair) or "nonfunctional" (remove). Appropriate measurements on contrasted CT can categorize definitively functional or nonfunctional kidneys with UPJO, negating the need for RG to obtain DRF in a majority of cases. This study design favors real-world application with potential to reduce medical expenditure and delay in definitive treatment.

Can selective arterial clamping with fluorescence imaging preserve kidney function during robotic partial nephrectomy?

OBJECTIVE

To compare renal functional outcomes in robotic partial nephrectomy (RPN) with selective arterial clamping guided by near-infrared fluorescence (NIRF) imaging to a matched cohort of patients who underwent RPN without selective arterial clamping and NIRF imaging.

METHODS

From April 2011 to December 2012, NIRF imaging-enhanced RPN with selective clamping was used in 42 cases. Functional outcomes of successful cases were compared with a cohort of patients, matched by tumor size, preoperative estimated glomerular filtration rate (eGFR), functional kidney status, age, sex, body mass index, and American Society of Anesthesiologists score, who underwent RPN without selective clamping and NIRF imaging.

RESULTS

In matched-pair analysis, selective clamping with NIRF was associated with superior kidney function at discharge, as demonstrated by postoperative eGFR (78.2 vs 68.5 mL/min/1.73 m(2); P = .04), absolute reduction of eGFR (-2.5 vs -14.0 mL/min/1.73 m(2); P <.01), and percent change in eGFR (-1.9% vs -16.8%; P <.01). Similar trends were noted at 3 month follow-up, but these differences became nonsignificant (P[eGFR] = .07; P[absolute reduction of eGFR] = .10; and P[percent change in eGFR] = .07). In the selective clamping group, a total of 4 perioperative complications occurred in 3 patients, all of which were Clavien grade I-III.

CONCLUSION

Use of NIRF imaging was associated with improved short-term renal functional outcomes when compared with RPN without selective arterial clamping and NIRF imaging. With this effect attenuated at later follow-up, randomized prospective studies and long-term assessment of kidney-specific functional outcomes are needed to further assess the benefits of this technology.

Near-infrared fluorescence imaging to facilitate super-selective arterial clamping during zero-ischaemia robotic partial nephrectomy

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: There is concern that warm ischaemia time during partial nephrectomy may have an adverse impact on postoperative renal function. As a result, there is increased interest in developing a safe and effective method for performing non-ischaemic partial nephrectomy. Several novel approaches have recently been described. We present our initial experience performing zero-ischaemia partial nephrectomy using near-infrared fluorescence imaging to facilitate super-selective arterial clamping. We report the operative and early postoperative outcomes from such cases as compared with a matched cohort of patients undergoing traditional partial nephrectomy with clamping of the main renal artery. We show that this technique is both safe and effective and may lead to improved renal preservation at short-term follow-up.

OBJECTIVE

To describe a novel technique of eliminating renal ischaemia during robotic partial nephrectomy (RPN) using near-infrared fluorescence (NIRF) imaging.

PATIENTS AND METHODS

Over an 8-month period (March 2011 to November 2011), 34 patients were considered for zero-ischaemia RPN using the da Vinci NIRF system. Targeted tertiary/higher-order tumour-specific branches were controlled with robotic bulldog(s) or neurosurgical aneurysm micro-bulldog(s). Indocyanine green dye was given, and NIRF imaging used to confirm super-selective ischaemia, defined as darkened tumour/peri-tumour area with green fluorescence of remaining kidney. Matched pair analysis was performed by matching each patient undergoing zero-ischaemia RPN (n = 27) to a previous conventional RPN (n = 27) performed by the same surgeon.

RESULTS

Of 34 patients, 27 (79.4%) underwent successful zero-ischaemia RPN; seven (20.6%) required conversion to main renal artery clamping (ischaemia time <30 min) for the following reasons: persistent tumour fluorescence after clamping indicating inadequate tumoral devascularization (n = 5), and parenchymal bleeding during RPN (n = 2). Matched-pair analysis showed comparable outcomes between cohorts, except for longer operating time (256 vs 212 min, P = 0.02) and superior kidney function (reduction of estimated glomerular filtration rate (-1.8% vs -14.9%, P = 0.03) in the zero-ischaemia cohort. All surgical margins were negative.

CONCLUSIONS

In this pilot study, we show that zero-ischaemia RPN with NIRF is a safe alternative to conventional RPN with main renal artery clamping. Eliminating global ischaemia may improve functional outcomes at short-term follow-up.

Management of localized prostate cancer and an incidental ureteral duplication with upper pole ectopic ureter inserting into the prostatic urethra

Ectopic ureters are rare congenital malformations of the renal system that most commonly present in females. It is extremely rare to encounter an ectopic ureter in an older man undergoing radical prostatectomy. We report herein a case of a 66-year-old man with prostate cancer and a complete duplication of the left renal collecting system, with an upper pole ectopic ureter and associated normal functioning renal parenchyma entering into the prostatic urethra. This anomaly was incidentally discovered on preoperative magnetic resonance imaging of the prostate. Open radical retropubic prostatectomy and a left ureteroureterostomy were performed.

Stereocontrol in the EtAlCl(2)-induced cyclization of chiral gamma,delta-unsaturated methyl ketones to form cyclopentanones

EtAlCl(2)-induced cyclization of chiral gamma,delta-unsaturated ketones 11c and 17b takes place mainly from the expected face. The selectivity is modest for 11c (60:40) in which the large substituent is a primary alkyl group and the medium substituent is a methyl group and excellent for 17b (93:7) in which the large substituent is a cyclohexyl group and the medium substituent is a methyl group. The cyclization of 17a is anomalous, suggesting that the phenyl group has more than a simple steric effect.