GDNF-independent ureteric budding: role of PI3K-independent activation of AKT and FOSB/JUN/AP-1 signaling.

A significant fraction of mice deficient in either glial cell-derived neurotrophic factor (GDNF) or its co-receptors (Gfrα1, Ret), undergoes ureteric bud (UB) outgrowth leading to the formation of a rudimentary kidney. Previous studies using the isolated Wolffian duct (WD) culture indicate that activation of fibroblast growth factor (FGF) receptor signaling, together with suppression of BMP/Activin signaling, is critical for GDNF-independent WD budding (Maeshima et al., 2007). By expression analysis of embryonic kidney from Ret((-/-)) mice, we found the upregulation of several FGFs, including FGF7. To examine the intracellular pathways, we then analyzed GDNF-dependent and GDNF-independent budding in the isolated WD culture. In both conditions, Akt activation was found to be important; however, whereas this occurred through PI3-kinase in GDNF-dependent budding, in the case of GDNF-independent budding, Akt activation was apparently via a PI3-kinase independent mechanism. Jnk signaling and the AP-1 transcription factor complex were also implicated in GDNF-independent budding. FosB, a binding partner of c-Jun in the formation of AP-1, was the most highly upregulated gene in the ret knockout kidney (in which budding had still occurred), and we found that its siRNA-mediated knockdown in isolated WDs also blocked GDNF-independent budding. Taken together with the finding that inhibition of Jnk signaling does not block Akt activation/phosphorylation in GDNF-independent budding, the data support necessary roles for both FosB/Jun/AP-1 signaling and PI3-kinase-independent activation of Akt in GDNF-independent budding. A model is proposed for signaling events that involve Akt and JNK working to regulate GDNF-independent WD budding.

Salvage ureteral reimplantation after failure of dextranomer/hyaluronic acid injection.

PURPOSE: Ureteroneocystostomy after dextranomer/hyaluronic acid injection is reportedly associated with significantly more morbidity, and increased operative time, length of stay and postoperative obstruction. To evaluate our experience, we reviewed results of patients who underwent salvage ureteral reimplantation following failed dextranomer/hyaluronic acid injection. MATERIALS AND METHODS: We retrospectively reviewed charts of patients at a single institution who underwent intravesical ureteral reimplantation as salvage treatment following failed dextranomer/hyaluronic acid injection. Data points such as operative time, blood loss and length of stay were compared to those of controls undergoing de novo reimplantation by the same surgeons. Statistical analysis was performed using Student's t test and chi-square test. RESULTS: We identified 18 patients who underwent salvage reimplant. We compared data to an equal number of controls. Mean age (4.28 years in patients vs 3.34 years in controls, p = 0.62) and mean reflux grade at reimplant (3.15 vs 3.40, p = 0.97) were comparable between the groups. Operative time (128 vs 141.9 minutes, p = 0.14), blood loss (12.9 vs 11.9 ml, p = 0.71) and length of hospital stay (1.68 vs 1.3 days, p = 0.25) were not significantly different. No statistically significant differences were found regarding any of the compared variables. CONCLUSIONS: Ureteral reimplantation after dextranomer/hyaluronic acid injection is no more difficult than primary ureteral reimplantation regarding operative time, blood loss and length of hospital stay. These results support dextranomer/hyaluronic acid as initial operative treatment of vesicoureteral reflux when deemed appropriate and may further shift the paradigm of treatment away from prolonged medical management.

Comparison of laparoendoscopic single-site, conventional laparoscopic, and open nephrectomy in a pediatric population.

INTRODUCTION: We provide a single-institution comparison of open, conventional laparoscopic (CL) and laparoendoscopic single-site (LESS) nephrectomy in children. METHODS: We identified all nephrectomy cases occurring at Rady Children's Hospital from July 2007 to March 2010. Exclusion criteria included redo/bilateral operations, malignancy, transplant nephrectomy, or complex urogenital anomalies. We compared patient demographics, total operative times, estimated blood loss (EBL), length of stay (LOS), complication rates, postoperative pain score, narcotic usage, and total hospital costs. RESULTS: We identified 7 LESS, 11 CL, and 8 open nephrectomy patients who met our criteria. The mean age of patients was 8.5, 7.3, and 4.2 years for LESS, CL, and open nephrectomy, respectively (P=.217). Operative times were 192.2, 219.3, and 127.4 minutes for LESS, CL, and open nephrectomy, respectively (P=.076). EBL was 15, 13.2, and 12.5 mL, respectively, for these groups (P=.871). There were no complications in any of the groups, although 1 LESS patient required conversion to open nephrectomy for bleeding. Mean LOS was 46.8, 36.9, and 33.8 hours in the LESS, CL, and open nephrectomy groups (P=.308). Mean pain scores on postoperative day 1 were 2.3, 1.8, and 1.6 in each group, respectively (P=.518). Hospital costs were comparable between the LESS and CL groups. The mean cost for open nephrectomy was 54.4% the mean cost for CL, however (P=.001). CONCLUSIONS: LESS nephrectomy in children is safe and overall comparable with CL. In our experience, no modality confers a distinct advantage except for the decreased cost associated with open surgery.

Early experience with laparoendoscopic single-site surgery in the pediatric urology patient population.

BACKGROUND AND PURPOSE: To present our initial experience with single-incision laparoscopy in the pediatric urologic population. PATIENTS AND METHODS: Four patients underwent eight single-incision laparoscopic procedures. One patient underwent bilateral nephrectomies, a hernia repair, and an orchiectomy. The remaining three patients underwent unilateral nephrectomies. All procedures were performed in children using the Covidien SILS port system via an umbilical incision. RESULTS: Procedures in three of four patients, representing seven of eight cases, were successfully performed via a single incision. Operative times ranged from 114 minutes to 360 minutes. There were no conversions to traditional laparoscopy. One nephrectomy was converted to an open procedure secondary to bleeding. There were no complications postoperatively, and at follow-up, all wounds were well healed. CONCLUSIONS: Single-incision laparoscopic urologic surgery is safe and feasible in the pediatric population. The umbilical (trans or peri) approach confers improved cosmesis over traditional laparoscopy, and the scar is essentially concealed.

Constructing kidney-like tissues from cells based on programs for organ development: toward a method of in vitro tissue engineering of the kidney.

The plausibility of constructing vascularized three-dimensional (3D) kidney tissue from cells was investigated. The kidney develops from mutual inductive interactions between cells of the ureteric bud (UB), derived from the Wolffian duct (WD), and the metanephric mesenchyme (MM). We found that isolated MMs were capable of inducing branching morphogenesis of the WD (an epithelial tube) in recombination cultures; suggesting that the isolated MM retains inductive capacity for WD-derived epithelial tubule cells other than those from the UB. Hanging drop aggregates of embryonic and adult renal epithelial cells from UB and mouse inner medullary collecting duct cell (IMCD) lines, which are ultimately of WD origin, were capable of inducing MM epithelialization and tubulogenesis with apparent connections (UB cells) and collecting duct-like tubules with lumens (IMCD). This supports the view that the collecting system can be constructed from certain epithelial cells (those ultimately of WD origin) when stimulated by MM. Although the functions of the MM could not be replaced by cultured mesenchymal cells, primary MM cells and one MM-derived cell line (BSN) produced factors that stimulate UB branching morphogenesis, whereas another, rat inducible metanephric mesenchyme (RIMM-18), supported WD budding as a feeder layer. This indicates that some MM functions can be recapitulated by cells. Although engineering of a kidney-like tissue from cultured cells alone remains to be achieved, these results suggest the feasibility of such an approach following the normal developmental progression of the UB and MM. Consistent with this notion, implants of kidney-like tissues constructed in vitro from recombinations of the UB and MM survived for over 5 weeks and achieved an apparently host-derived glomerular vasculature. Lastly, we addressed the issue of optimal macro- and micro-patterning of kidney-like tissue, which might be necessary for function of an organ assembled using a tissue engineering approach. To identify suitable conditions, 3D reconstructions of HoxB7-green fluorescent protein mouse rudiments (E12) cultured on a filter or suspended in a collagen gel (type I or type IV) revealed that type IV collagen 3D culture supports the deepest tissue growth (600 +/- 8 microm) and the largest kidney volume (0.22 +/- 0.02 mm(3)), and enabled the development of an umbrella-shaped collecting system such as occurs in vivo. Taken together with prior work (Rosines et al., 2007; Steer et al., 2002), these results support the plausibility of a developmental strategy for constructing and propagating vascularized 3D kidney-like tissues from recombinations of cultured renal progenitor cells and/or primordial tissue.

Impaired Wnt-beta-catenin signaling disrupts adult renal homeostasis and leads to cystic kidney ciliopathy.

Cystic kidney disease represents a major cause of end-stage renal disease, yet the molecular mechanisms of pathogenesis remain largely unclear. Recent emphasis has been placed on a potential role for canonical Wnt signaling, but investigation of this pathway in adult renal homeostasis is lacking. Here we provide evidence of a previously unidentified canonical Wnt activity in adult mammalian kidney homeostasis, the loss of which leads to cystic kidney disease. Loss of the Jouberin (Jbn) protein in mouse leads to the cystic kidney disease nephronophthisis, owing to an unexpected decrease in endogenous Wnt activity. Jbn interacts with and facilitates beta-catenin nuclear accumulation, resulting in positive modulation of downstream transcription. Finally, we show that Jbn is required in vivo for a Wnt response to injury and renal tubule repair, the absence of which triggers cystogenesis.

C-reactive protein, interleukin-6, and prostate cancer risk in men aged 65 years and older.

Inflammation is believed to play a role in prostate cancer (PCa) etiology, but it is unclear whether inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6) associate with PCa risk in older men. Using Cox regression, we assessed the relationship between baseline concentrations of CRP and IL-6 and the subsequent PCa risk in the Cardiovascular Health Study, a population-based cohort study of mostly European American men of ages >64 years (n = 2,234; mean follow-up = 8.7 years; 215 incident PCa cases). We also tested associations between CRP and IL-6 tagSNPs and PCa risk, focusing on SNPs that are known to associate with circulating CRP and/or IL-6. Neither CRP nor IL-6 blood concentrations was associated with PCa risk. The C allele of IL-6 SNP rs1800795 (-174), a known functional variant, was associated with increased risk in a dominant model (HR = 1.44; 95% CI = 1.03-2.01; p = 0.03), but was not statistically significant after accounting for multiple tests (permutation p = 0.21). Our results suggest that circulating CRP and IL-6 do not influence PCa risk. SNPs at the CRP locus are not associated with PCa risk in this cohort, while the association between rs1800795 and PCa risk warrants further investigation.

Perinatal testicular torsion: preoperative radiological findings and the argument for urgent surgical exploration.

Perinatal testicular torsion is an infrequent event, the management of which has been controversial. Occurrence is rare, estimated at 1 in 7500 newborns (Kaplan, G. W., Silber, I.: Neonatal torsion--to pex or not? In: Urologic surgery in neonates and young infants. Edited by King, L.R. Philadelphia: W.B. Saunders Co., 1988; Chapter 20, pp. 386-395). The frequency of bilateral perinatal torsion is up to 22% (J Urol. 2005;174:1579). Here, we describe two cases of bilateral asynchronous perinatal torsion, in which the only presenting abnormality on exam after birth was a unilateral scrotal mass. These cases illustrate that contralateral perinatal torsion may be present even when physical exam findings suggest unilateral involvement.

Modified bladder neck reconstruction in patients with incontinence after staged exstrophy/epispadias closures.

PURPOSE: Reconstruction of the urethra without adequate circumferential muscular support is a significant problem in bladder neck surgery for urinary incontinence. Fascial, muscular and artificial slings have been used for support of the bladder neck after reconstruction. We used a demucosalized detrusor muscle pedicle to wrap around the bladder neck base along with other continence techniques in children who experienced incontinence after staged closure of exstrophy and epispadias. We describe our experience using the pedicle wraparound along with the Mitchell modification of Young-Dees-Leadbetter bladder neck reconstruction. MATERIALS AND METHODS: We reviewed our continence rates using a detrusor wraparound in 8 eligible patients with failed staged exstrophy-epispadias repair. We defined incontinence as any degree of leakage through the bladder neck day or night. RESULTS: Of the 8 patients studied 2 were female and 6 were male. Mean patient age at surgery was 7.6 years (range 4 to 11). Mean followup was 3.2 years (range 0.5 to 5). All patients with staged exstrophy-epispadias repair failure are currently continent. Five patients underwent simultaneous bladder augmentation. All but 2 patients catheterize via a Mitrofanoff channel. Three patients void volitionally and 5 use clean intermittent catheterization per Mitrofanoff. Two patients required dextranomer/hyaluronic acid injections at the bladder neck postoperatively to achieve complete dryness. CONCLUSIONS: The detrusor bladder neck wraparound, while successful, may require concomitant surgery, including augmentation, clean intermittent catheterization and endoscopic injection therapy, to achieve continence following failure of staged exstrophy-epispadias repair. The detrusor bladder neck wrap appears to be a safe and effective adjunctive procedure in this patient population. We believe it has an important role in the achievement of urinary dryness.