Exploring the Landscape of Aptamers: From Cross-Reactive to Selective to Specific, High-Affinity Receptors for Cocaine.

We reported over 20 years ago MNS-4.1, the first DNA aptamer with a micromolar affinity for cocaine. MNS-4.1 is based on a structural motif that is very common in any random pool of oligonucleotides, and it is actually a nonspecific hydrophobic receptor with wide cross-reactivity with alkaloids and steroids. Despite such weaknesses preventing broad applications, this aptamer became widely used in proof-of-concept demonstrations of new formats of biosensors. We now report a series of progressively improved DNA aptamers recognizing cocaine, with the final optimized receptors having low nanomolar affinity and over a thousand-fold selectivity over the initial cross-reactants. In the process of optimization, we tested different methods to eliminate cross-reactivities and improve affinity, eventually achieving properties that are comparable to those of the reported monoclonal antibody candidates for the therapy of overdose. Multiple aptamers that we now report share structural motifs with the previously reported receptor for serotonin. Further mutagenesis studies revealed a palindromic, highly adaptable, broadly cross-reactive hydrophobic motif that could be rebuilt through mutagenesis, expansion of linker regions, and selections into receptors with exceptional affinities and varying specificities.

Growth in Newborn Circumcisions Performed by Pediatric Urologists and Advanced Practice Providers Between 2010 and 2021 in the United States.

OBJECTIVE: To characterize changes in the proportion of newborn circumcisions performed by pediatric urologists and advanced practiced providers (APPs) in the United States over the last decade. METHODS: The Merative MarketScan Commercial Database was queried for newborn circumcision private health insurance claims (Common Procedural Terminology 54150) between 2010 and 2021. Setting (inpatient/outpatient), US Census Bureau region, clinician specialty, and patient age (days) were determined for the full study time period, and by study year. Simple linear regression assessed growth in proportion of newborn circumcisions performed by pediatric urologists and APPs (nurse practitioner/physician assistant/midwife), over time. RESULTS: In total, 1,006,748 newborn circumcisions (59% inpatient) were identified; while most were performed by obstetricians (45%) or pediatricians (33%); APPs performed 0.9%, and pediatric urologists performed 0.7%. From 2010-2021, the proportion of newborn circumcisions performed by pediatric urologists increased from 0.3% to 2.0% and by APPs in from 0.5% to 2.9% (P < .001 for both). Growth for both pediatric urologists and APPs occurred APPs predominantly from 2016 to 2021. Trends in proportion of newborn circumcision performed by pediatricians was stable [31.5% (2010) and 32.5% (2021)], but decreased for obstetricians [48.8% (2014) and 38.1% (2021)]. CONCLUSION: The proportion of newborn circumcisions performed by pediatric urologists and APPs increased more than 6-fold between 2010 and 2021, though both specialties still perform a minority of newborn circumcisions. These data provide important baseline information for newborn circumcision workforce planning, including evaluating collaborative care models where pediatric urologists train APPs to perform circumcision.

Retrograde incision from orifice (RIO) technique for endoscopic incision of ureterocele: 15 years of outcomes.

INTRODUCTION: Management of obstructing ureterocele often includes endoscopic transurethral incision (TUI) that can be challenging secondary to uncertainty in anatomic landmarks with risk of serious complications. To this end, we innovated a technique using predictable landmarks that begins endoscopic incision at the ureterocele orifice and extends retrograde proximal to the bladder neck (Figure). OBJECTIVE: With over 15 years of experience in performing this retrograde incision from orifice (RIO) technique, we aimed to examine post-operative outcomes and risk of surgical failure after RIO compared to traditional TUI techniques for ureteroceles. We hypothesized that clinical outcomes after RIO would be superior to traditional endoscopic approaches to decompression of obstructing ureterocele in infants. STUDY DESIGN: A retrospective study of patients ≤12 months old who underwent TUI ureterocele at our institution between 2007 and -2021 was conducted. Pre-, intra- and post-operative characteristics were compared between patients who underwent RIO vs non-RIO TUI. Primary outcome was post-incision febrile urinary tract infection (fUTI). Secondary outcome was a composite failure measure of fUTI, secondary surgery, de novo bladder outlet obstruction, or vesicoureteral reflux. Multivariable Cox proportional hazard models were fitted to compare the time-to-event risk of primary and secondary outcomes between groups. RESULTS: Ninety patients with 92 ureteroceles were included (49 RIO, 43 non-RIO). Median follow-up from TUI was 33 months. RIO had a shorter median operative duration (27 vs 35 min, p = 0.021). Primary and secondary outcomes were similar between groups (fUTI: 29% RIO vs 19% non-RIO, p = 0.27; composite failure 54% RIO vs 69% non-RIO, p = 0.15). In multivariable Cox proportional hazard models, there was no significant difference in risk of fUTI (RIO aHR 0.98, 95% CI 0.38-2.54, p = 0.97) or composite failure (RIO aHR 0.80, 95% CI 0.45-1.44, p = 0.46) between TUI techniques. DISCUSSION: RIO technique for TUI ureterocele is attractive in that it uses predictable anatomic landmarks making it simple to perform. In analyzing this 15-year institutional experience of TUI ureterocele, RIO showed similar success to non-RIO endoscopic incisions. This study is a retrospective, non-randomized, single-institutional study over 15 years and is therefore subject to change in surgeon practice over time and variable practices between providers. CONCLUSIONS: Given comparable success and durability over time to other TUI ureterocele techniques, and with the advantage of operator ease using consistent anatomic landmarks, RIO is a worthy option for endoscopic ureterocele decompression.

Robot-assisted Laparoscopic Pyeloplasty: Experience of a Single Pediatric Institution, Including Long-term and Safety Outcomes.

OBJECTIVE: To evaluate the efficacy and safety of robot-assisted laparoscopic pyeloplasty (RALP) and describe the short and long-term outcomes of pediatric RALP. METHODS: We retrospectively reviewed all patients ..±21 years old who underwent primary RALP from 7/2007 through 12/2019. Patients were excluded from postoperative analysis if follow-up data after stent removal was not available. The primary outcome was surgical success, defined as radiographic improvement of hydronephrosis without need for reoperation. Secondary outcomes were time to reoperation and 90-day complication rate. RESULTS: A total of 356 patients underwent primary repair of ureteropelvic junction obstruction during the study period; 29.ßpatients were limited to intraoperative data due to lack of follow-up imaging. Radiographic improvement at latest follow-up was seen in 308/327 (94.2%). Ten of 327 patients (3.1%) underwent reoperation: 7 were identified within 1 year of RALP and 3 were identified over 1 year after RALP. The median time to reoperation was 13.0 months (IQR 9.3-21.7). We defined long-term as>3 years after pyeloplasty. Over one-third (122/327, 37.3%) of the cohort had>3 years of follow-up, none of whom developed evidence of recurrent obstruction requiring reoperation beyond 3 years. Complications occurred within 90 days of surgery in 20/327 (6.1%). CONCLUSION: This largest single-institution series confirms short- and long-term surgical effectiveness and safety of RALP. Our data also indicate that most patients who needed reoperation were identified within 1 year, and reoperation more than 3 years after RALP is rare.

Streamlining surgical trays for common pediatric urology Procedures: A quality improvement initiative.

INTRODUCTION: Procedures involving the external genitalia are the most common pediatric urologic operations. Our group identified excess instrumentation for these cases to be a potential cause of operating room (OR) inefficiency at our large, freestanding pediatric hospital. This quality improvement (QI) initiative aimed to streamline surgical instrumentation for the most-performed pediatric urologic procedures at our hospital. MATERIAL AND METHODS: Six Sigma DMAIC methodology (Define, Measure, Analyze, Improve, Control) guided this multidisciplinary, iterative QI effort. A stakeholder team utilized data review, direct observations, and multiple in-person discussions to create a new "Groin-Penis Tray" (GPT) to replace a larger tray for the 90 most common pediatric urologic procedures. Suture preference cards and expectations about which sutures would be opened for each case were updated. The primary outcome was estimated yearly cost-avoidance due to reduced sterile processing. Additional outcomes included: instruments opened/case, % cases with complete trays, Mayo stand set-up time, and % cases with unused sutures. Balancing measures included: total median OR time and tray weights. Baseline and post-implementation measures were characterized and compared. RESULTS: A QI professional, 10 pediatric urologists, 2 pediatric urology fellows, and multiple OR and sterile processing staff members participated. The Summary Figure compares baseline and post-implementation measurements. The number of instruments opened/case decreased from 146 to 65. Annual sterile reprocessing costs decreased by >$51,000. Median Mayo stand set-up time decreased from 7.3 to 3.5 min (p < 0.001). The number of cases with complete trays increased from 7/20 (35%) to 11/20 (55%, p = 0.34). The new GPT is 2.7 kg lighter than the prior tray. Median OR time remained stable (baseline: 91 min; post-implementation: 102 min, p = 0.44). The number of cases with suture waste decreased from 78% to 0% immediately post-implementation but increased to 40% one year later. DISCUSSION: This systematic, iterative QI process spanned the course of ∼2 years, including planning, building, and updating new trays, then assessing longer-term success via the control phase. The new GPT is used for most pediatric urologic procedures at our hospital, and benefits include sterile reprocessing cost savings and ergonomics. Our team gained valuable experience related to assessing QI project scope, determining key stakeholders and roles, and strategies for sustainability that we will apply to future initiatives. CONCLUSIONS: Streamlining surgical trays for common pediatric urologic procedures at a large freestanding children's hospital using established QI methodology reduced OR cost by >$51,000/year and Mayo stand set-up times without compromising balancing measures.

Randomized trial of prophylactic antibiotics vs. placebo after midshaft-to-distal hypospadias repair: the PROPHY Study.

BACKGROUND: Use of prophylactic antibiotics after stented hypospadias repair is very common, but most research has not identified any clinical benefits of this practice. Only one study has found that postoperative prophylaxis reduces symptomatic urinary tract infections (UTIs). Data from the same trial suggested that prophylaxis may also reduce urethroplasty complications. No studies on this subject have been placebo-controlled. OBJECTIVE: We performed a randomized, double-blind, placebo-controlled study to evaluate the effect of postoperative prophylactic antibiotics on the incidence of infection or urethroplasty complications after stented repair of midshaft-to-distal hypospadias. STUDY DESIGN: Boys were eligible for this multicenter trial if they had a primary, single-stage repair of mid-to-distal hypospadias with placement of an open-drainage urethral stent for an intended duration of 5-10 days. Participants were randomized in a double-blind fashion to receive oral trimethoprim-sulfamethoxazole or placebo twice daily for 10 days postoperatively. The primary outcome was a composite of symptomatic UTI, surgical site infection (SSI), and urethroplasty complications, including urethrocutaneous fistula, meatal stenosis, and dehiscence. Secondary outcomes included each component of the primary outcome as well as acute adverse drug reactions (ADRs) and C. difficile colitis. RESULTS: Infection or urethroplasty complications occurred in 10 of 45 boys (22%) assigned to receive antibiotic prophylaxis as compared with 5 of 48 (10%) who received placebo (relative risk [RR], 2.1; 95% confidence interval [CI], 0.8 to 5.8; p = 0.16). There were no significant differences between groups in symptomatic UTIs, SSIs, or any urethroplasty complications. Mild ADRs occurred in 3 of 45 boys (7%) assigned to antibiotics as compared with 5 of 48 (10%) given placebo (RR, 0.6; 95% CI, 0.2 to 2.5; p = 0.72). There were no moderate-to-severe ADRs, and no patients developed C. difficile colitis. CONCLUSIONS: In this placebo-controlled trial of 93 patients, prophylactic antibiotics were not found to reduce infection or urethroplasty complications after stented mid-to-distal hypospadias repair. The study did not reach its desired sample size and was therefore underpowered to independently support a conclusion that prophylaxis is not beneficial. However, the result is consistent with most prior research on this subject. GOV IDENTIFIER: NCT02096159.

Safety and Efficacy of Robot-Assisted Laparoscopic Pyeloplasty Compared to Open Repair in Infants under 1 Year of Age.

PURPOSE: Robot-assisted laparoscopic pyeloplasty (RALP) use in children has increased, though many centers still favor open pyeloplasty (OP) in infants. This study aims to compare safety and efficacy of RALP and OP in infants. MATERIALS AND METHODS: A single-institution, retrospective cohort study of infants <1 year of age who underwent primary RALP or OP between January 2009 and June 2020 was performed. Primary outcomes were intraoperative and 30-day complications, postoperative radiographic improvement at last clinic visit, and operative failure leading to redo pyeloplasty. Multivariable logistic regression was performed for 30-day complications to adjust for demographic variation between groups. Survival analysis was performed to compare time to diagnosis of operative failure leading to redo pyeloplasty. RESULTS: Among 204 patients, 121 underwent OP and 83 underwent RALP (74.5% male). RALP patients were older (median 7.2 vs 2.9 months, p <0.001) and larger (median 8.2 vs 5.9 kg, p <0.001) than OP patients. Radiographic improvement was seen in 91.1% of RALP patients and 88.8% of OP patients at last visit. Median (interquartile range) followup in months was 24.4 (10.8-50.3) for the full cohort. In adjusted analysis, the odds of a 30-day complication (OR 0.40, 95% CI 0.08-2.00) was lower for RALP compared to OP, though not statistically significant. In survival analysis, there was no difference in time to diagnosis of operative failure and redo pyeloplasty between groups (p=0.65). CONCLUSIONS: RALP is a safe and effective alternative to OP for infants, with comparable intraoperative and 30-day complications, radiographic improvement at last followup, and risk of pyeloplasty failure.

Robot-assisted laparoscopic urologic surgery in infants weighing ≤10 kg: A weight stratified analysis.

INTRODUCTION: Robot-assisted laparoscopic (RAL) urologic surgery is widely used in pediatric patients, though less commonly in infants. There are small series demonstrating safety and efficacy in infants, however, stratification by infant size has rarely been reported. Whether a cut-off weight, below which RAL surgery is not technically feasible, safe, or efficacious has not be determined. OBJECTIVE: To assess safety and efficacy of RAL urologic procedures in infants <1 year of age, weighing ≤10 kg. STUDY DESIGN: A single-institution retrospective cohort study of patients <1 year of age, and ≤10 kg undergoing RAL pyeloplasty (RALP) or RAL ipsilateral ureteroureterostomy (RALUU) between January 2011 and September 2020 was performed. Demographic, operative, and post-operative data were extracted from the medical record. Patients were stratified by post-hoc weight quartiles. Outcomes, including operative time, total OR time, estimated blood loss (EBL), post-operative length of stay (LOS), post-operative radiographic improvement, and 30-day complications were assessed by weight quartile for each procedure. The Kruskal-Wallis rank test was used to assess differences in continuous outcomes between weight quartiles and Pearson's Chi-squared test was used for categorical outcomes. RESULTS: Of 696 RAL urologic surgeries performed, 101 met eligibility criteria. Median (IQR) age of patients was 7.2 (6.0-9.2) months with median weight of 8.0 (7.2-8.9) kg. The lowest weight was 5.5 kg. Procedures performed included 79 RALPs (78.2%), 22 RALUUs (21.8%). We identified 97 patients (94%) with post-operative imaging, with radiographic improvement in 92%. When stratified by weight quartile, there was no difference between groups in median operative time, total OR time, LOS, EBL, or post-operative radiographic improvement for both RALP and RALUU. Post-operative complications were assessed based on Clavien-Dindo classification with the majority of complications (9/12, 75%) in the >50th percentile weight groups. DISCUSSION: To our knowledge, this is the largest published series of infant RAL urologic procedures, with similar rates of radiographic improvement and post-operative complications to prior published series. There are few prior series of RALP and RALUU in infants ≤10 kg, and we show comparable outcomes regardless of patient weight. Our study is limited by the inherent biases of retrospective studies. CONCLUSION: RAL urologic surgery is technically feasible, safe, and efficacious in infants ≤10 kg, without worse outcomes as weight decrease. A cut-off weight, below which RAL surgery should not be performed has yet to be identified.

Challenging proximal hypospadias repairs: An evolution of technique for two stage repairs.

INTRODUCTION: Proximal hypospadias repair remains challenging. Our approach to the first stage of two-stage proximal hypospadias repairs has evolved from using Byars' flaps to preputial inlay grafts in anatomically suitable cases and pedicled preputial flaps in more complex repairs. We reviewed our outcomes, hypothesizing that inlay grafts and pedicled preputial flaps were associated with lower complication risks than Byars' flaps. STUDY DESIGN: A single institution, retrospective, cohort study of consecutive two-stage, primary, proximal hypospadias repairs performed from 2007 to 2017 was conducted. Patients with <6 months follow-up and incomplete operative reports were excluded. Risk of complications (fistula, dehiscence, diverticulum, meatal stenosis, stricture) were evaluated following urethroplasty and stratified by first-stage repair technique. As technique refinements have been made since 2012, comparisons between two temporal subgroups (those who underwent repair in 2007-2012 and in 2013-2017) were made. RESULTS: 78 of 127 patients met inclusion criteria. Overall complication rate was 47% (Summary Table). Median follow-up was 25.4 months (range 6.4-128.5 months) after urethroplasty. Pedicled preputial flaps (hazards ratio [HR] 0.30; 95% Confidence Interval [CI] 0.14-0.65) and inlay grafts (HR 0.32; 95% CI 0.11-0.95) were associated with lower complication risks compared to Byars' flaps (Summary Table). Median time to complication was significantly shorter for Byars' flaps (5.7 months) than for inlay grafts (40.6 months) and pedicled preputial flaps (79.2 months) by Kaplan Meier analysis. Temporal subgroup comparisons showed that overall complication rates decreased from 70% to 31% (p = 0.001), but differences in complication rates by first-stage technique were not statistically significant. DISCUSSION: In our cohort, repairs with Byars' flaps had the highest complication rate, which is consistent with our observations that urethras tubularized from Byars' flaps lack appropriate backing and are hypermobile and irregular. To overcome these shortcomings, modifications were made to our approach to two-stage proximal hypospadias repairs with the use of inlay grafts and pedicled preputial flaps quilted to the underlying corporal bodies to optimize the stability of the urethral plate. Our preliminary results are promising. CONCLUSION: Approach to the first stage of two-stage repairs affects outcomes. Pedicled preputial flaps and inlay grafts were associated with lower complication risks than Byars' flaps. Refinement of technique and patient selection may have resulted in fewer complications in the short term. However, long-term follow-up is needed.

Urinary Tract Infection After Robot-assisted Laparoscopic Pyeloplasty: Are Urine Cultures and Antibiotics Helpful?

OBJECTIVE: To evaluate how variations in peri-operative urine culture (UCx) and antibiotic prophylaxis utilization following robot assisted laparoscopic pyeloplasty (RALP) affect post-RALP urinary tract infection (UTI) rates in children, then use data to generate a standardized care pathway. METHODS: Patients undergoing RALP at a single institution from January 2014 to October 2018 were retrospectively reviewed. Patients with vesicoureteral reflux, neurogenic bladder, intermittent catheterization, <=2 months follow-up after stent removal, or age >=18 years were excluded. UCx use, UCx results, and pre- and post-RALP antibiotic use were recorded. The primary outcome was symptomatic UTI, tracked until 60 days after stent removal. UTI was defined as presence of fever or urinary symptoms, a positive UCx with >=10,000 colony forming units of one uropathogen, and a positive urinalysis. RESULTS: A total of 152 patients were included (72% male [73% circumcised], 61% white, and 23% Hispanic). One underwent a re-operative pyeloplasty, yielding 153 encounters. Eight patients (5.2%; 95% CI 1.7-8.7%) developed post-RALP UTI. Uncircumcised status and use of pre-operative prophylactic antibiotics were associated with post-RALP UTI (P = .03 and P < .01, respectively). Use of post-RALP antibiotics, whether prophylactic or therapeutic, was not associated with lower UTI rates (P = .92). Positive pre-RALP UCx and positive intra-operative stent removal UCx were associated with higher UTI rates (P = .03 and P < .01, respectively). CONCLUSION: UTI occurred in 5.2% of our cohort of >150 patients. As post-RALP antibiotic use was not associated with lower UTI rates, prophylactic antibiotics may be reserved for patients with risk factors. A standardized care pathway could safely reduce unnecessary utilization of UA/UCx and antibiotics.

Association between intra-operative meatal mismatch and urethrocutaneous fistula development in hypospadias repair.

INTRODUCTION: The Glans-Meatus-Shaft (GMS) Score is a pre-operative phenotypic scoring system used to assess hypospadias severity and risk for post-operative complications. The 'M' component is based on pre-operative meatal location, but meatal location sometimes changes after penile degloving, resulting in 'meatal mismatch.' OBJECTIVE: To identify: 1) the incidence and clinical predictors of meatal mismatch, and 2) the association of meatal mismatch with post-operative urethrocutaneous fistula development. STUDY DESIGN: We performed a retrospective cohort study on patients who underwent primary hypospadias repair at a single center from 2011 to 2018. Meatal mismatch was defined as: upstaging (meatus moving more proximally after degloving), downstaging (moving more distally after degloving), or none. Covariates included: pre-degloving meatal location, chordee severity, penoscrotal anatomy, pre-operative testosterone, and number of stages for repair. To test the association between meatal mismatch and fistula development, we constructed two, nested, multivariable Cox proportional hazards regression models with and without meatal mismatch and compared them with the likelihood ratio test. A sensitivity analysis excluded patients with <6 months of follow-up. RESULTS: Of 485 patients, 99 (20%) exhibited meatal mismatch, including 75 (15%) with upstaging and 24 (5%) patients with downstaging (Figure). Meatal mismatch was significantly associated with penoscrotal webbing, number of stages for repair, and pre-degloving meatal location, with downstaging being associated with more proximal meatal location. Over a median follow-up of 7.3 months (interquartile range 2.0-20.9), fistulae developed in 56 (12%) patients. On multivariable analysis, meatal upstaging was associated with a 3-fold increased risk of fistula development (Hazards Ratio [HR]: 3.04, 95% Confidence Interval [CI]: 1.44-6.45) compared to no mismatch. Meatal downstaging had similar risk of fistula development compared to no mismatch (HR: 0.99, 95% CI: 0.29-3.35). Multi-stage compared to single-stage repair was associated with reduced risk of fistula development (HR: 0.24, 95% CI: 0.09-0.66). The likelihood ratio test favored the model that included meatal mismatch. The sensitivity analysis showed similar findings. DISCUSSION: Our short-term results suggest that meatal mismatch may be an important additional consideration to the GMS score as a tool to assess hypospadias severity, counsel families, and predict outcomes. Longer-term studies are needed to enhance the precision of risk stratification in hypospadias. CONCLUSIONS: Meatal mismatch occurred in 20% of patients undergoing hypospadias repair. Among this cohort, meatal upstaging was associated with a 3-fold increased risk of post-operative urethrocutaneous fistula development.

Are pressure pop-offs beneficial to the bladder in boys with posterior urethral valves?

BACKGROUND: Pressure pop-offs, such as high-grade vesicoureteral reflux with renal dysplasia, have historically been considered beneficial for renal and bladder outcomes in boys with posterior urethral valves (PUV). Recent longer-term studies have called into question the beneficial effects of pop-offs on renal function. OBJECTIVE: To evaluate how pop-offs affect bladder outcomes in boys with PUV. STUDY DESIGN: At a single-center, the electronic medical records of boys with PUV who underwent valve ablation from 2000 to 2014 were retrospectively reviewed for bladder and continence outcomes. Patients were excluded due to presentation after one year of age, age at last follow-up <1 year, lack of urodynamic study (UDS), lack of voiding cystourethrogram, or concomitant prune belly syndrome. Between patients with and without pop-offs, the following outcomes were compared: prevalence of significant hydronephrosis (Society for Fetal Urology grade 3 or 4) prior to valve ablation and at last follow-up, nadir creatinine level, classification of initial UDS, type of medical and/or surgical interventions, dryness during the day and toilet-training status at last follow-up (among patients ≥4 years), and age at toilet-training. For patients with multiple UDS, initial and latest UDS were compared. RESULTS: 48 patients met inclusion criteria, of whom 31 (65%) had pop-offs and 17 (35%) did not. Median age at last follow-up was 5.9 years (range: 1.0-12.2 years). Patients with pop-offs were more likely to have unsafe initial UDS (26% vs. 12%, p = 0.15) but less likely to have high voiding pressures at their latest UDS (15% vs. 50%, p = 0.03). Patients with pop-offs were more likely to have used clean intermittent catheterization (26% vs. 0%, p = 0.04) and were less likely to be toilet-trained by age 4 (76% vs. 100%, p = 0.15) or dry during the day at last follow-up (56% vs. 92%, p = 0.06). Toilet-trained patients with pop-offs were toilet-trained by an earlier age than patients without pop-offs (3 vs 4 years, p = 0.04). DISCUSSION: The results of the present retrospective study show that patients with pop-offs required more extensive interventions to achieve continence, and achieved continence and toilet-training less frequently than patients without pop-offs. Additionally, our results demonstrated that patients with pop-offs had worse bladder dynamics initially, which may suggest that pop-offs are a manifestation of more excessive pressure build-up prior to valve ablation. CONCLUSIONS: Among boys with posterior urethral valves who present in the first year of life, pop-offs do not appear to impart significant benefit to bladder outcomes and may indicate more severe bladder dysfunction.

The Homeodomain Transcription Factor NKX3.1 Modulates Bladder Outlet Obstruction Induced Fibrosis in Mice.

Fibrosis is an irreversible remodeling process characterized by the deposition of collagen in the extracellular matrix of various organs through a variety of pathologies in children, leading to the stiffening of healthy tissues and organ dysfunction. Despite the prevalence of fibrotic disease in children, large gaps exist in our understanding of the mechanisms that lead to fibrosis, and there are currently no therapies to treat or reverse it. We previously observed that castration significantly reduces fibrosis in the bladders of male mice that have been partially obstructed. Here, we investigated if the expression of androgen response genes were altered in mouse bladders after partial bladder outlet obstruction (PO). Using a QPCR microarray and QRTPCR we found that PO was sufficient to increase expression of the androgen response gene Nkx3.1. Consistent with this was an increase in the expression of NKX3.1 protein. Immunofluorescent antibody localization demonstrated nuclear NKX3.1 in most bladder cells after PO. We tested if genetic deletion of Nkx3.1 alters remodeling of the bladder wall after PO. After PO, Nkx3.1 KO/KO bladders underwent remodeling, demonstrating smaller bladder area, thickness, and bladder: body weight ratios than obstructed, wild type controls. Remarkably, Nkx3.1 KO/KO specifically affected histological parameters of fibrosis, including reduced collagen to muscle ratio. Loss of Nkx3.1 altered collagen and smooth muscle cytoskeletal gene expression following PO which supported our histologic findings. Together these findings indicated that after PO, Nkx3.1 expression is induced in the bladder and that it mediates important pathways that lead to tissue fibrosis. As Nkx3.1 is an androgen response gene, our data suggest a possible mechanism by which fibrosis is mediated in male mice and opens the possibility of a molecular pathway mediated by NKX3.1 that could explain sexual dimorphism in bladder fibrosis.

Stem cell antigen/Ly6a protects against bladder fibrosis in mice.

We have defined a population of stem cell antigen (Sca)-1+/CD34+/lin- mesenchymal stem cells in the mouse urinary bladder. These cells are reduced after partial bladder outlet obstruction (PO). To test the role of Sca-1 expressed by these cells, we analyzed bladders from Sca-1 knockout (KO) mice in both uninjured male mice and male mice subjected to PO. We found that loss of Sca-1 alone had little effect on bladder development or function but reduced the total number of mesenchymal stem cells by 30%. After PO, bladders from Sca-1-null KO male mice were larger, with more collagen and less muscle, than obstructed wild-type mice. Steady-state levels of caldesmon were significantly reduced and levels of fibroblast-specific protein 1 were significantly increased in Sca-1 KO mice compared with wild-type mice after PO. In investigating the effects of PO on cell proliferation, we found that loss of Sca-1 changed the timing of cell division in CD34+/lin-, collagen-producing, and smooth muscle cells. PO in combination with loss of Sca-1 drastically reduced the ability of CD34+/lin- cells to form colonies in vitro. Our findings therefore support the hypothesis that Sca-1 protects the bladder from fibrotic remodeling after obstruction, in part by influencing the proliferation of cells responding to the injury.

Robot-Assisted Laparoscopic Reoperative Repair for Failed Pyeloplasty in Children: An Updated Series.

PURPOSE: Reoperative pyeloplasty is commonly used in children with recurrent obstruction after pyeloplasty. We previously reported on reoperative robot-assisted laparoscopic repair for failed pyeloplasty in 16 children and concluded that short-term and intermediate outcomes were comparable to open reoperative repair. In this updated series we describe longer term outcomes from an extended study. MATERIALS AND METHODS: We retrospectively reviewed outcomes of consecutive children with prior failed primary pyeloplasty who underwent robot-assisted laparoscopic reoperative repair at a single institution from January 2008 to June 2018. RESULTS: Overall, 36 children 0.6 to 15.2 years old (median 3.7) underwent robot-assisted laparoscopic reoperative repair (pyeloplasty in 31, ureterocalicostomy in 5) at a median of 24.3 months (range 3.9 to 136.7) after primary repair. Median reoperative time was 285.0 minutes (range 207 to 556) and median length of stay was 1 day (1 to 8). Crossing vessels were present in 8 of 30 children (26.7%) with prior open repair and in 0 of 6 with prior minimally invasive repair. Clavien-Dindo grade 1 to 2 perioperative complications occurred in 4 children (11.1%) and grade 3 to 5 complications in 2 (5.6%). Median followup was 35.3 months (range 1.4 to 108.3), with 18 children (50.0%) being followed for more than 3 years. Postoperative ultrasound in 34 children revealed improvement in 31 (91.2%), stability in 2 (5.9%) and worsening hydronephrosis in 1 (2.9%). All 11 children undergoing preoperative and postoperative diuretic renography demonstrated stable or improved differential renal function. All children were symptom-free at last followup. CONCLUSIONS: To our knowledge, this is the largest series of robot-assisted laparoscopic reoperative repair for failed pyeloplasty in children. Our results indicate the feasibility, efficacy, safety and durability of this procedure.

Ureteral Complications of Pediatric Renal Transplantation.

PURPOSE: Ureteral complications following renal transplantation are more common in children than in adults. We identify potential risk factors for ureteral complications in pediatric patients. MATERIALS AND METHODS: We retrospectively studied a cohort of patients who underwent renal transplantation at Lurie Children's Hospital between 2004 and 2016. We analyzed the associations between patient characteristics, operative factors, graft characteristics and postoperative complications. RESULTS: A total of 224 renal transplantations in 219 patients were identified. Preexisting bladder pathology was present in 25% of cases. Overall rate of ureteral complications was 16%, with symptomatic vesicoureteral reflux being the most common. Ureteral complications were seen significantly more frequently in patients with underlying bladder pathology (26% vs 12%, p = 0.01). Rate of postoperative vesicoureteral reflux in patients with bladder pathology was lower when a urologist performed the reimplantation but the difference was not statistically significant (15% vs 27%, p = 0.35). Urologists were significantly more likely to perform the ureteral anastomosis in patients on clean intermittent catheterization (85% vs 43%, p = 0.004) and in patients with a history of complex bladder reconstruction (75% vs 28%, p <0.001). CONCLUSIONS: Patients with existing bladder pathology are at increased risk for ureteral complications, particularly vesicoureteral reflux. Since pediatric urologists routinely perform ureteral reimplantation in patients with existing bladder pathology, these patients may benefit from a multidisciplinary approach between urology and transplant surgery at renal transplantation.

Voided volumes predict degree of partial bladder outlet obstruction in a murine model.

The partial bladder outlet obstruction animal model (pBOO) is commonly used as a model for obstructive uropathy. Unfortunately, pBOO demonstrates variable degrees of obstruction requiring bladder weight (BW) or urodynamic studies to determine true obstruction. Our objective is to identify extent of obstruction by correlating early post-operative Void Stains on Paper (VSOP) assays with ultimate BW in mice. pBOO was performed on 32 mice 1- and 4-week VSOPs were quantified for mean voided volume (mVV). At 4 weeks, bladders were harvested and weighed. Correlation was evaluated through bivariate kernel density estimation and a Pearson correlation coefficient (SAS). Single variable histogram of the data established groups based on BWs and mVV. mVV's and bladder weights within group pairings were averaged and plotted to render a non-linear regression model. A significant correlation was found between 1-week mVVs and 4-week BWs upon bivariate analysis with a correlation coefficient of -0.758 (p = 0.0294). A non-linear regression of plotted data defined a statistically significant fit equation correlating 1-week mVV to 4-week BW. We demonstrate a novel method for forecasting degree of obstruction in pBOO based on 1-week post-operative VSOP mVV.