Urinary aquaporin 1 and perilipin 2: Can these novel markers accurately characterize small renal masses and help guide patient management?

OBJECTIVE: To evaluate the role of urine aquaporin 1 and perilipin 2 as biomarkers adjunct to renal mass biopsy in guiding the management of patients with small renal masses. METHODS: Preoperative aquaporin 1 and perilipin 2 levels in 57 patients with small renal masses undergoing partial nephrectomy were analyzed and compared with postoperative tumor histology. An algorithm was created utilizing aquaporin 1 and perilipin 2 in conjunction with renal mass biopsy. Cut-off values were implemented to maximize biomarker sensitivity and specificity. Renal mass biopsy utilization and intervention were then compared with rates in traditional renal mass biopsy algorithms. RESULTS: All clear cell and papillary renal cell carcinomas were correctly identified and assigned to the treatment path. All benign lesions were correctly sorted to a confirmatory renal mass biopsy path. Two chromophobe masses did not have elevated aquaporin 1 and perilipin 2, and would require renal mass biopsy. Compared with protocols that call for all small renal masses to be biopsied, confirmatory renal mass biopsy could have been safely avoided in 74% of patients with elevated aquaporin 1 and perilipin 2. Compared with protocols that do not utilize renal mass biopsy, surgical intervention would have been avoided in 23% of patients with benign masses. CONCLUSIONS: Aquaporin 1 and perilipin 2 possess high sensitivity and specificity for detecting clear cell and papillary renal cell carcinoma. Use of these markers might compliment renal mass biopsy in the characterization of small renal masses.

In vivo bypass of 8-oxodG.

8-oxoG is one of the most common and mutagenic DNA base lesions caused by oxidative damage. However, it has not been possible to study the replication of a known 8-oxoG base in vivo in order to determine the accuracy of its replication, the influence of various components on that accuracy, and the extent to which an 8-oxoG might present a barrier to replication. We have been able to place a single 8-oxoG into the Saccharomyces cerevisiae chromosome in a defined location using single-strand oligonucleotide transformation and to study its replication in a fully normal chromosome context. During replication, 8-oxoG is recognized as a lesion and triggers a switch to translesion synthesis by Pol η, which replicates 8-oxoG with an accuracy (insertion of a C opposite the 8-oxoG) of approximately 94%. In the absence of Pol η, template switching to the newly synthesized sister chromatid is observed at least one third of the time; replication of the 8-oxoG in the absence of Pol η is less than 40% accurate. The mismatch repair (MMR) system plays an important role in 8-oxoG replication. Template switching is blocked by MMR and replication accuracy even in the absence of Pol η is approximately 95% when MMR is active. These findings indicate that in light of the overlapping mechanisms by which errors in 8-oxoG replication can be avoided in the cell, the mutagenic threat of 8-oxoG is due more to its abundance than the effect of a single lesion. In addition, the methods used here should be applicable to the study of any lesion that can be stably incorporated into synthetic oligonucleotides.

Cell type specific changes in BMP-7 expression contribute to the progression of kidney disease in patients with obstructive uropathy.

PURPOSE: Congenital urinary tract obstruction is a leading cause of renal maldevelopment and pediatric kidney disease. Nonetheless, few groups have examined its molecular pathogenesis in humans. We evaluated the role of BMP-7, a protein required for renal injury repair and nephrogenesis, in disease progression in patients with obstructive uropathy. MATERIALS AND METHODS: Whole kidney and cell specific BMP-7 expression was examined in a murine model of unilateral ureteral obstruction and in patients with congenital ureteropelvic junction obstruction. Findings were correlated with molecular markers of renal injury and clinical parameters. RESULTS: Unilateral ureteral obstruction led to a dramatic decrease in BMP-7 expression in the proximal and distal tubules before the onset of significant loss of renal architecture and fibrosis, suggesting that this is a critical molecular event that drives early stage disease progression. Loss of BMP-7 expression then extended to the collecting ducts and glomeruli in end stage kidney disease. When translating these findings to patients with ureteropelvic junction obstruction, global loss of BMP-7 expression correlated with a decreased number of nephrons, loss of renal architecture, severe renal fibrosis and loss of kidney function. CONCLUSIONS: Given that BMP-7 has a critical role in renal injury repair and nephrogenesis, these findings show that cell specific changes in BMP-7 expression contribute to the onset of irreversible renal injury and impaired kidney development secondary to congenital urinary tract obstruction. Accordingly therapies that target these cell populations to restore BMP-7 activity may limit disease progression in patients with obstructive uropathy.

HDAC dependent transcriptional repression of Bmp-7 potentiates TGF-ß mediated renal fibrosis in obstructive uropathy.

PURPOSE: Recombinant BMP-7 inhibits the pathogenesis of renal injury in response to various stimuli. However, little is known about the molecular regulation of endogenous BMP-7 and its renal protective functions. We examined transcriptional regulation of Bmp-7 and its role in the pathogenesis of renal injury resulting from urinary tract dysfunction. MATERIALS AND METHODS: Obstruction induced renal injury was modeled in vivo in mice by unilateral ureteral obstruction and in vitro in primary kidney cells by treatment with transforming growth factor-ß, a profibrotic cytokine that is increased in the obstructed kidney. RESULTS: Unilateral ureteral obstruction resulted in the loss of BMP-7 expression in conjunction with histone deacetylation and transcriptional repression of the Bmp-7 promoter. The histone deacetylase inhibitor trichostatin A stimulated Bmp-7 expression in primary kidney cells. Trichostatin A also inhibited the expression of transforming growth factor-ß dependent profibrotic genes in a manner that depended on BMP receptor signaling. These findings extended to the obstructed kidney in vivo, in which trichostatin A treatment restored the expression of Bmp-7 along with BMP-7 mediated suppression of transforming growth factor-ß dependent signaling pathways. Finally, trichostatin A stimulated activation of the BMP-7 pathway the ameliorated obstruction induced renal injury by preventing disruption of the renal architecture and the development of renal fibrosis. CONCLUSIONS: These findings show that histone deacetylase dependent repression of Bmp-7 transcription is a critical event during the pathogenesis of renal injury in obstructive uropathy. Accordingly, treatment with histone deacetylase inhibitors represents a potentially effective strategy to restore BMP-7 expression and its renal protective functions during treatment of obstructive uropathy.

Limited use of surveillance imaging following nephrectomy for renal cell carcinoma.

OBJECTIVES: To evaluate the utilization of follow-up imaging after nephrectomy for renal cell carcinoma (RCC) in nationally representative data. PATIENTS AND METHODS: Using Surveillance, Epidemiology, End Results data linked to Medicare records, we identified patients with RCC who received nephrectomy from 1991 to 2007. Patients were stratified by tumor stage. Postoperative chest and abdominal imaging (including chest x-ray, computed tomography scan, and magnetic resonance imaging; abdominal ultrasound, computed tomography scan, and magnetic resonance imaging) was assessed. Observed surveillance imaging frequency was compared to published protocols. Predictors of initial and continued yearly surveillance imaging were identified. RESULTS: Agreement between observed imaging frequency and evidence-based surveillance protocols was low, particularly for patients with T2-T4 disease. For patients who were not censored before 13 months, initial abdominal and chest surveillance imaging was obtained in 69% and 78% of patients, respectively. By year 5, 28% and 39% of patients with high-risk disease (T3 or T4), as compared to 21% and 25% of patients with low to moderate risk disease (T1 and T2), received yearly surveillance abdominal and chest imaging, respectively. High-risk disease was predictive of initial chest (odds ratio [OR] = 1.38) and abdominal (OR = 1.6) imaging, as well as continued yearly chest (hazard ratio [HR] = 0.73) and abdominal (HR = 0.74) imaging surveillance. For abdominal imaging, more contemporary year of surgery was predictive of initial (1997-2001, OR = 1.6; 2002-2007, OR = 2.4) and continued yearly surveillance (1997-2001, HR = 0.82; 2002-2007; HR = 0.67). CONCLUSIONS: In the Medicare population, surveillance imaging is performed in a limited number of patients following nephrectomy for RCC. However, increasing tumor stage is predictive of both increased chest and abdominal imaging surveillance.

Epithelioid Angiomyolipoma in a Pediatric Patient: Case Report and Review of Literature.

We report a case of a 17-year-old girl with tuberous sclerosis complex who underwent partial nephrectomy for a newly discovered 7.5-cm renal mass subsequently determined to be an epithelioid angiomyolipoma, a rare variant of angiomyolipoma that can be confused clinically, radiographically, and pathologically for renal cell carcinoma. Proper diagnosis and treatment are critical, especially in the pediatric patient. This case report and review of literature serve at increasing the awareness of this renal tumor, with its somewhat unpredictable outcome, reviewing the pertinent literature on the topic of epithelioid angiomyolipoma in the clinical setting of tuberous sclerosis complex.

Urethrography interpretation skills of urology and radiology residents at tertiary care medical centers.

OBJECTIVE: To assess the ability of urology and radiology residents to interpret retrograde urethrograms (RUGs) and voiding cystourethrograms (VCUGs). METHODS: A standardized examination of 10 combination RUGs and VCUGs of the male urethra was administered to urology and radiology residents from all levels of training at Washington University, Stanford University, and Northwestern University. Residents were asked to evaluate stricture location(s) and length, if present. RESULTS: Sixty residents participated, consisting of 26 from Washington University, 15 from Stanford University, and 19 from Northwestern University. Average years of training for urology and radiology were 3.6 and 2.8 years, respectively (P=.01). Normal RUGs and VCUGs were recognized by 18 of 31 radiologists (58%) and 19 of 29 urologists (65.5%; P=.5). Anterior strictures were correctly identified in 145 of 403 (36%) and 165 of 377 (43.8%) responses by radiologists and urologists, respectively (P=.03). Posterior strictures were correctly identified in 20 of 62 (32.3%) and 10 of 58 (17.2%) responses by radiologists and urologists, respectively (P=.09). When both groups of residents were combined, anterior strictures were identified correctly more often than posterior strictures (39.7% vs 25%; P<.01). Overall accuracy was 24.2% (75 of 310) for the radiology group and 27.9% (81 of 290) for the urology group (P=.30). In the presence of multiple strictures, accuracy declined to 7.26% (9 of 124) for the radiology group and 9.48% (11 of 116) for the urology group (P=.5), with a combined accuracy of 8.33% (20 of 240). CONCLUSION: Radiology and urology residents in the United States have poor skills at interpreting urethrography, especially when multiple strictures or posterior strictures are present. A formal educational program for RUG and VCUG interpretation should be designed and implemented into the radiology and urology resident curriculum.

The second "time-out": a surgical safety checklist for lengthy robotic surgeries.

Robotic surgeries of long duration are associated with both increased risks to patients as well as distinct challenges for care providers. We propose a surgical checklist, to be completed during a second "time-out", aimed at reducing peri-operative complications and addressing obstacles presented by lengthy robotic surgeries. A review of the literature was performed to identify the most common complications of robotic surgeries with extended operative times. A surgical checklist was developed with the goal of addressing these issues and maximizing patient safety. Extended operative times during robotic surgery increase patient risk for position-related complications and other adverse events. These cases also raise concerns for surgical, anesthesia, and nursing staff which are less common in shorter, non-robotic operations. Key elements of the checklist were designed to coordinate operative staff in verifying patient safety while addressing the unique concerns within each specialty. As robotic surgery is increasingly utilized, operations with long surgical times may become more common due to increased case complexity and surgeons overcoming the learning curve. A standardized surgical checklist, conducted three to four hours after the start of surgery, may enhance perioperative patient safety and quality of care.

Camera-port site metastasis of a renal-cell carcinoma after robot-assisted partial nephrectomy.

BACKGROUND AND PURPOSE: Port-site metastasis (PSM) is a rare complication of laparoscopic intervention in urologic malignancies. Of the greater than 50 reported cases of PSM in the urologic oncology literature, only 9 have occurred after surgery for renal-cell carcinoma (RCC). We report a 10th instance of RCC metastasis-in this case to the camera-port site after robot-assisted partial nephrectomy (RAPN). To our knowledge, this case is the first reported PSM of RCC after RAPN. PATIENT AND METHODS: A 68-year-old man underwent an uncomplicated right RAPN for a 4-cm right renal mass (stage T1aN0M0). Five months later, he was found to have metastatic disease with an isolated peritoneal recurrence at the camera-port site. Biopsy of the lesion confirmed RCC, and the lesion was surgically resected. A comprehensive MEDLINE search for all published studies of port-site recurrences after laparoscopic renal surgery for RCC was performed. RESULTS: Nine cases of PSM after successful laparoscopic radical or partial nephrectomy for locally confined RCC have been reported. Proposed etiologic factors for port-site recurrence include biologic aggressiveness of the tumor, patient immunosuppression, local wound factors, and technique-related factors. We report an unusual case of PSM to a camera port that was not used for specimen manipulation or extraction. CONCLUSION: PSM after laparoscopic renal surgery for RCC is a rare occurrence. Our case, in which PSM occurred without specimen bag rupture or extraction through the port in question, highlights the importance of local and systemic factors in contributing to PSM occurrence. We also demonstrate that when PSM is the only site of disease recurrence, it can be successfully managed with minimally invasive surgical resection.

Endoscopic management of genitourinary foreign bodies.

Retrieval of foreign bodies from the genitourinary system, most commonly inserted for sexual satisfaction or as a result of a psychiatric illness, can pose a significant surgical challenge. Due to their breadth of size, shape, and location within the genitourinary system, endoscopic management can be difficult. Here, we review the management of four cases of foreign object insertion into the genitourinary system and their outcomes and management.

Transformation with oligonucleotides creating clustered changes in the yeast genome.

We have studied single-strand oligonucleotide (oligo) transformation of yeast by using 40-nt long oligos that create multiple base changes to the yeast genome spread throughout the length of the oligos, making it possible to measure the portions of an oligo that are incorporated during transformation. Although the transformation process is greatly inhibited by DNA mismatch repair (MMR), the pattern of incorporation is essentially the same in the presence or absence of MMR, whether the oligo anneals to the leading or lagging strand of DNA replication, or whether phosphorothioate linkages are used at either end. A central core of approximately 15 nt is incorporated with a frequency of >90%; the ends are incorporated with a lower frequency, and loss of the two ends appears to be by different mechanisms. Bases that are 5-10 nt from the 5' end are generally lost with a frequency of >95%, likely through a process involving flap excision. On the 3' end, bases 5-10 nt from the 3' end are lost about 1/3 of the time. These results indicate that oligos can be used to create multiple simultaneous changes to the yeast genome, even in the presence of MMR.