Identification of genetic variants associated with anterior cruciate ligament rupture and AKC standard coat color in the Labrador Retriever.

Canine anterior cruciate ligament (ACL) rupture is a common complex disease. Prevalence of ACL rupture is breed dependent. In an epidemiological study, yellow coat color was associated with increased risk of ACL rupture in the Labrador Retriever. ACL rupture risk variants may be linked to coat color through genetic selection or through linkage with coat color genes. To investigate these associations, Labrador Retrievers were phenotyped as ACL rupture case or controls and for coat color and were single nucleotide polymorphism (SNP) genotyped. After filtering, ~ 697 K SNPs were analyzed using GEMMA and mvBIMBAM for multivariate association. Functional annotation clustering analysis with DAVID was performed on candidate genes. A large 8 Mb region on chromosome 5 that included ACSF3, as well as 32 additional SNPs, met genome-wide significance at P < 6.07E-7 or Log10(BF) = 3.0 for GEMMA and mvBIMBAM, respectively. On chromosome 23, SNPs were located within or near PCCB and MSL2. On chromosome 30, a SNP was located within IGDCC3. SNPs associated with coat color were also located within ADAM9, FAM109B, SULT1C4, RTDR1, BCR, and RGS7. DZIP1L was associated with ACL rupture. Several significant SNPs on chromosomes 2, 3, 7, 24, and 26 were located within uncharacterized regions or long non-coding RNA sequences. This study validates associations with the previous ACL rupture candidate genes ACSF3 and DZIP1L and identifies novel candidate genes. These variants could act as targets for treatment or as factors in disease prediction modeling. The study highlighted the importance of regulatory SNPs in the disease, as several significant SNPs were located within non-coding regions.

Utility of retrograde ureterocelogram in management of complex ureterocele.

INTRODUCTION: Symptomatic pediatric ureterocele has diverse manifestations, making evidence-based management impractical. Thus, detailed visualization of ureterocele anatomy prior to first surgical incision is invaluable. Retrograde ureterocelogram (RUC) is a simple, underutilized radiologic technique that can be performed during cystoscopy. This study sought to determine whether RUC changes surgical management by more accurately depicting the complex ureteral and ureterocele anatomy, compared with renal ultrasound (US) and voiding cystourethrography (VCUG). METHODS: Patients who underwent surgical management of ureterocele from 2003 to 2015 were identified; those who received concomitant fluoroscopic RUC were selected for the case series. Data collected included: demographics, pre-operative evaluation, surgical interventions, and outcomes. The RUC images were individually examined, and the anatomic impression compared with previous renal US and VCUG. Novel RUC findings not previously appreciated by the pre-operative evaluation were noted. The RUC was performed by cystoscopically inserting a needle into the ureterocele and injecting contrast retrograde. If indicated, simultaneous PIC (Positioning the Instillation of Contrast) cystography was performed. RESULTS: Of the 43 patients that underwent surgery for suspected ureterocele, 28 underwent cystoscopy + RUC (10 M: 18 F) at a median age of 4.6 months and median follow-up of 37.0 months. All patients had prior US, 25 had prior VCUG, and 20 had prior radionuclide studies. Ureteroceles were either duplex system (n = 21) or single system (n = 7); 17 were ectopic into the bladder neck or urethra; seven were intravesical; and four were pseudoureteroceles. Fourteen patients underwent concomitant transurethral incision of the ureterocele (TUIU); two were deferred for surgery; and 11 received concomitant definitive surgery (e.g., nephrectomy). The RUC illuminated novel aspects of the anatomy in 20 of the 28 patients. No adverse events occurred. Notably, in nine of the 28 children, significant observations from RUC prompted change to the pre-operative surgical plan. DISCUSSION: Retrograde ureterocelogram clearly revealed ureterocele ectopy, pseudoureterocele, ureterocele disproportion, and unsuspected duplex systems, making it a useful adjunct to standard US and VCUG studies. Retrograde ureterocelogram can also be used to fluoroscopically verify decompression of the ureterocele post incision, document severity of ureteral dilation, and teach residents about the great damage generated by ureterocele variations. Limitations of RUC included increasing radiation dose and overall cost. The study design was limited by its small size, retrospective approach, selection bias, and availability of RUC images. CONCLUSIONS: While not indicated in routine ureterocele management, intraoperative RUC further defined ureterocele anatomy in nearly all cases and yielded changes to the original surgical plan frequently enough to merit greater use in complex patients.

Clitoral hoodplasty in females with disorders of sex development.

INTRODUCTION: The surgical management of girls with masculinized genitalia is gradually changing towards a more conservative approach. Reports on loss of clitoral sensitivity and related impairment of sexual function in women after feminizing genital surgery in childhood have been pivotal in this evolution. An exposed clitoral glans is occasionally seen at follow-up, and while patients may complain of aesthetics, no clitoral discomfort secondary to glans exposure has been reported. A technique has been developed to reconstruct the clitoral hood and the present study reports the preliminary results. OBJECTIVES: To report the novel technique and preliminary results of clitoral hood reconstruction to cover an exposed glans after previous clitoroplasty in patients with congenital adrenal hyperplasia (CAH). PATIENTS AND METHODS: Six female patients (mean age 13, range 4-21 years) with CAH sought medical help for clitoral concerns after previous reduction clitoroplasty. In two of the six patients, the main complaint was clitoral hypersensitivity or even pain. The clitoral glans was completely exposed in all patients, who were subsequently treated with a bi-laminar V-Y clitoral hoodplasty to create a mobile and natural-looking clitoral hood composed of an inner and outer preputial skin layer. RESULTS: Postoperative covering of the glans was complete in five patients, and partial in one. The two patients with pre-operative pain became asymptomatic; all six patients were pleased with the cosmetic postoperative results. CONCLUSION: Clitoral hoodplasty provides simple, yet effective, relief for women with cosmetic concerns or clitoral discomfort after previous feminizing surgery.

Impact and frequency of extra-genitourinary manifestations of prune belly syndrome.

INTRODUCTION: Prune belly syndrome (PBS) extra-genitourinary (extra-GU) manifestations are serious comorbidities beyond the genitourinary (GU) anomalies of this disease. We hypothesized an underestimation of the reported frequency and understated impact on quality of life (QOL) of extra-GU comorbidities in PBS survivors beyond the newborn period. To assess this, the frequencies of extra-GU manifestations of PBS in a contemporary cohort of living patients were compared to compiled frequencies from published literature. Second, the impact of extra-GU PBS manifestations on patient/family QOL was assessed via a non-validated open-ended survey. MATERIAL AND METHODS: From 2010 to 2013, PBS survivors were prospectively recruited locally or at three PBS Network National Conventions. The family/subject was asked to complete a detailed PBS questionnaire, non-validated QOL survey, and provide medical records for review. Clinical data were extracted from medical records for local patients. The frequencies of extra-GU manifestations were compared between the contemporary, living cohort and a published literature cohort derived from PubMed. RESULTS AND DISCUSSION: Seven of 706 published studies met criteria for frequencies tabulation of extra-GU PBS manifestations. This largest reported living PBS patient cohort (n = 65) was 99% male with mean age 10 years (1 month-45 years). The living PBS cohort had a statistically significantly higher incidence of gastrointestinal (63%), orthopedic (65%), and cardiopulmonary (49%) diagnoses compared to the compiled published cohort (n = 204). Eleven PBS males and 32 family members completed the QOL survey. Of these, 47% listed at least one non-GU problem (i.e. lung disease, skeletal problems, constipation) as negatively affecting their QOL; 42% listed at least one GU problem (i.e. self-catheterization, recurrent UTIs) as negatively affecting their QOL; 56% reported musculoskeletal surgery and 21% reported gastrointestinal surgery/medication as positively impacting their QOL. CONCLUSIONS: In this large contemporary series, surviving individuals with PBS had a significantly higher incidence of orthopedic, gastrointestinal, and cardiopulmonary diagnoses than previously reported in PBS publications. From the patient/family QOL perspective, non-GU PBS manifestations negatively impact their QOL and treatment of these non-GU conditions improves their lives. As urologic surgeons for these medically complex patients, it is extremely important to be aware of and prepare for the high incidence of non-GU PBS comorbidities directly impacting the medical and surgical treatment and QOL of PBS patients and their families.

c-Myc and Her2 cooperate to drive a stem-like phenotype with poor prognosis in breast cancer.

The HER2 (ERBB2) and MYC genes are commonly amplified in breast cancer, yet little is known about their molecular and clinical interaction. Using a novel chimeric mammary transgenic approach and in vitro models, we demonstrate markedly increased self-renewal and tumour-propagating capability of cells transformed with Her2 and c-Myc. Coexpression of both oncoproteins in cultured cells led to the activation of a c-Myc transcriptional signature and acquisition of a self-renewing phenotype independent of an epithelial-mesenchymal transition programme or regulation of conventional cancer stem cell markers. Instead, Her2 and c-Myc cooperated to induce the expression of lipoprotein lipase, which was required for proliferation and self-renewal in vitro. HER2 and MYC were frequently coamplified in breast cancer, associated with aggressive clinical behaviour and poor outcome. Lastly, we show that in HER2(+) breast cancer patients receiving adjuvant chemotherapy (but not targeted anti-Her2 therapy), MYC amplification is associated with a poor outcome. These findings demonstrate the importance of molecular and cellular context in oncogenic transformation and acquisition of a malignant stem-like phenotype and have diagnostic and therapeutic consequences for the clinical management of HER2(+) breast cancer.

Carbon, nitrogen, and phosphorus fluxes in household ecosystems in the Minneapolis-Saint Paul, Minnesota, urban region.

Rapid worldwide urbanization calls for a better understanding of the biogeochemical cycling of those macroelements that have large environmental impacts in cities. This study, part of the Twin Cities Household Ecosystem Project, quantified fluxes of carbon (C), nitrogen (N), and phosphorus (P) at the scale of individual households in the Minneapolis-Saint Paul metropolitan area in Minnesota, USA. We estimated input and output fluxes associated with several components of household activities including air and motor vehicle travel, food consumption, home energy use, landscape, pets, and paper and plastic use for 360 owner-occupied, stand-alone households. A few component fluxes dominated total input fluxes of elements. For instance, air and motor vehicle transportation, together with home energy use, accounted for 85% of total C consumption and emissions. All total and component fluxes were skewed to varying degrees, suggesting that policies targeting disproportionately high fluxes could be an effective and efficient way to reduce pollution. For example, 20% of households contributed 75% of air travel emissions and 40% of motor vehicle emissions. Home energy use was more nearly normally distributed. Nitrogen fluxes were dominated by human diet and lawn fertilizer applications, which together accounted for 65% of total household N inputs. The majority of P inputs were associated with human diet, use of detergents, and pet food. A large portion of the variation among household fluxes of C, N, and P was related to a few biophysical variables. A better understanding of the biophysical, demographic, and behavioral drivers of household activities that contribute to C, N, and P fluxes is pivotal for developing accurate urban biogeochemical models and for informing policies aimed at reducing sources of pollution in urban ecosystems.

Psychopathic personality in children: genetic and environmental contributions.

BACKGROUND: The current study investigates whether the underlying factor structure of psychopathic personality traits found in adults is similar to that in children and what the extent of the genetic and environmental influences are on these psychopathic traits. METHOD: Psychopathic personality traits were assessed in a community sample of 1219 twins and triplets (age 9-10 years) through caregiver reports of each child's behavior using the Child Psychopathy Scale (CPS). RESULTS: Confirmatory factor analyses revealed an optimal two-factor solution (callous/disinhibited and manipulative/deceitful) to the CPS subscales. Bivariate genetic modeling of the two computed factor scores revealed significant genetic as well as unique environmental influences on psychopathic personality traits in both boys and girls, with heritability estimates of 0.64 and 0.46, respectively, in boys and 0.49 and 0.58, respectively, in girls. No shared environmental influences on psychopathic personality traits were found. CONCLUSIONS: The relationship between the two factors was mediated by both genetic and unique environmental factors common to both traits.

Prechemotherapy laparoscopic nephrectomy for Wilms' tumor.

Laparoscopic radical nephrectomy is emerging as the treatment of choice for localized renal malignancies in adults. Despite the widespread use of laparoscopic nephrectomy for benign renal disease in infants and children, the laparoscopic approach has not been employed for pediatric Wilms' tumor except following systemic chemotherapy. We report the results of laparoscopic radical nephrectomy for removal of unilateral Wilms' tumor prior to the administration of systemic chemotherapy in two patients.

The newborn exstrophy bladder inadequate for primary closure: evaluation, management and outcome.

PURPOSE: The surgical approach to the small newborn exstrophy bladder inadequate for primary closure remains undetermined. Various methods for long-term management have been implemented. We evaluated our experience with late primary closure of the small exstrophied bladder template. MATERIALS AND METHODS: Our institutional database of patients treated and followed for the exstrophy-epispadias complex was reviewed. Of these patients 19 had a bladder template that was too small to close in the newborn period. The treatment and outcome of these 19 patients were reviewed. RESULTS: Of the 19 children who had delayed closure due to a small bladder template 14 were males and 5 were females. Followup from birth ranged from 2 to 36 years (mean 18 years). Primary closure was performed at a mean patient age of 13 months (range 6 months to 2 years). Pelvic osteotomy was performed in 16 patients. Of the 19 patients 9 achieved continence after gaining a bladder capacity sufficient for bladder neck reconstruction, 4 required enterocystoplasty to augment bladder volume and perform clean intermittent catheterization (2 per stoma and 2 per urethra), 1 required a colon conduit for an extremely small bladder, and 1 underwent cystectomy and ureterosigmoidostomy for rhabdomyosarcoma. Four patients are currently incontinent, including 3 who are awaiting bladder neck reconstruction and 1 who has frequent nighttime incontinence that is medically managed. CONCLUSIONS: Delayed primary closure of the small bladder exstrophy template can allow the native bladder tissue adequate time to grow to a size feasible for successful closure. Epispadias repair can usually be performed at the same time and is facilitated by prior testosterone administration. Bladder neck reconstructive techniques have achieved continence without the need for augmentation or bladder replacement in 47% of the patients in our series. For patients who do not achieve adequate capacity for bladder neck reconstruction, preservation of the native bladder template facilitates future augmentation and ureteral reimplantation, thus requiring use of less bowel in the growing child.

Combined bladder neck reconstruction and epispadias repair for exstrophy-epispadias complex.

PURPOSE: The achievement of satisfactory continence in the management of classic bladder exstrophy remains a surgical challenge. During the last 20 years a staged approach to the management of the exstrophy-epispadias complex has been used at many exstrophy centers to attain this goal. In select cases repairs can be combined to reduce the number of mandatory operations to achieve continence. We retrospectively review our experience with, and long-term results and complications of combined bladder neck reconstruction and epispadias repair. MATERIALS AND METHODS: A total of 19 boys with classic bladder exstrophy (17) and complete male epispadias (2) underwent combined bladder neck reconstruction and epispadias repair between 1982 and 1999. Primary closure was performed elsewhere in 16 cases and osteotomy was performed at primary closure in 8 (42%). All patients have undergone modified Cantwell-Ransley epispadias repair except for 2 who underwent a Young procedure. RESULTS: At the time of combined bladder neck and epispadias repair mean patient age was 5.2 years (range 2.5 to 10). Mean bladder capacity was 119 ml. (range 60 to 250). Of the 19 patients 13 (69%) are completely continent, and 2 (11%) are partially continent and 1 remained incontinent. Three patients did not gain satisfactory functional bladder capacity after combined repair, and underwent bladder augmentation and a continent diversion procedures. CONCLUSIONS: Combined bladder neck and epispadias repair is applicable in experienced hands but careful patient selection and long-term followup are the most important issues to develop criteria to select those best to undergo this procedure.

Modified Young-Dees-Leadbetter bladder neck reconstruction in patients with successful primary bladder closure elsewhere: a single institution experience.

PURPOSE: Achievement of urinary continence in patients with the exstrophy-epispadias complex remains a challenge. We reviewed our experience with the modified Young-Dees-Leadbetter bladder neck repair in patients with bladder exstrophy who underwent primary bladder closure elsewhere. MATERIALS AND METHODS: We retrospectively reviewed exstrophy charts and database of 57 male and 11 female with classic bladder exstrophy who underwent bladder neck repair at our institute and successful primary bladder closure elsewhere during the last 2 decades. Osteotomy was performed at primary closure in 14 (20%) cases and 9 (13%) patients at bladder neck repair in 9 (13%) to aid in stabilizing the urethra and pelvic ring, and to help reapproximate the pelvic floor musculature facilitating urinary continence. RESULTS: Primary closure was done within 72 hours of life elsewhere in 41 (60%) patients, and between ages 72 hours and 5 years (most during the first month of life) in 27. Paraexstrophy skin flaps were used in 33 (48%) cases, and the most common complication was bladder outlet obstruction of the posterior urethra secondary to the skin flaps. Of the 68 patients 57 (83%) are continent and voiding per urethra without need for augmentation or clean intermittent catheterization, 9 (13%) required clean intermittent catheterization including 7 who underwent continent urinary diversion after failed bladder neck repair, and 2 are still incontinent due to a severe posterior urethral stricture. Urinary retention was the most common symptom after bladder neck repair which resolved following catheter dilation or prolonged suprapubic catheter drainage. CONCLUSIONS: Successful early primary closure of a good bladder template is the most important determinant of eventual bladder capacity and compliance.

A multi-institutional analysis of laparoscopic orchidopexy.

OBJECTIVE: To combine and analyse the results from centres with a large experience of laparoscopy for the impalpable testis with small series, to determine the expected success rate for laparoscopic orchidopexy. METHODS: A questionnaire was distributed to participating paediatric urologists; each contributor retrospectively reviewed the clinical charts for their cases of therapeutic laparoscopy for an impalpable testis, detailing 36 variables for each patient. The data were collated centrally into a computerized database. For inclusion, the testis was intra-abdominal (including 'peeping' at the internal ring) at laparoscopic examination, was not managed through an open approach and did not undergo orchidectomy. Three surgical groups were assessed, with success defined as lack of atrophy and intrascrotal position: group 1, primary laparoscopic orchidopexy; group 2, a one-stage Fowler-Stephens (F-S) orchidopexy; and group 3, a two-stage F-S orchidopexy. RESULTS: Data were gathered from 10 centres in the USA, covering the period 1990-1999; 252 patients representing 310 testes were included and overall, 15.2% were lost to follow-up. There was no significant difference between success rates in the larger and smaller series. Atrophy occurred in 2.2% of 178 testes, 22.2% of 27 testes and 10.3% of 58 testes in groups 1-3, respectively. Testes were not in a satisfactory scrotal position in 0.6%, 7.4% and 1.7% of groups 1-3, respectively. The mean follow-up for each group was 7.7, 8.6 and 20.0 months, respectively. The overall success for all groups was 92.8% (97.2% group 1; 74.1% group 2; 87.9% group 3), with an atrophy rate of 6.1%. CONCLUSION: Laparoscopic orchidopexy for the intra-abdominal testis, in both large and small series, can be expected to have a success rate higher than that historically ascribed to open orchidopexy. Within this series, single-stage F-S laparoscopic orchidopexy resulted in a significantly higher atrophy rate than the two-stage repair. However, when considering both F-S approaches, the laparoscopic approach gave greater success than previously reported for the same open approaches. Despite the weaknesses inherent in a retrospective unrandomized study, we conclude that laparoscopic orchidopexy is, if not the procedure of choice, an acceptable and successful approach to the impalpable undescended testicle.

Nitrogen transformations in a wetland receiving lagoon effluent: sequential model and implications for water reuse.

Constructed wetlands could be components of low-tech systems to treat and reuse wastewater in arid region. A key function of the wetland would be to provide additional N removal. To improve design criteria, a sequential model of nitrogen transformations (organic N --> ammonium: ammonium --> nitrate: nitrate --> nitrogen gas) was successfully calibrated and verified for a wetland in Kingman, Arizona. A sequential model has the ability to "recognize" species of nitrogen in the influent and predict species of nitrogen in the effluent. Model scenarios show that increasing nitrification rates in the summer and denitrification rates in the winter would improve nitrogen removal efficiencies. Several lines of evidence suggest that wintertime denitrification may be limited by carbon supply. Winter carbon supply could be augmented by routing a portion of the water through channels planted with dryland vegetation.

Multicompartment ecosystem mass balances as a tool for understanding and managing the biogeochemical cycles of human ecosystems.

Nitrogen remains a ubiquitous pollutant in surface and groundwater throughout the United States, despite 30 years of pollution control efforts. A detailed multicompartment N balance for the Central Arizona-Phoenix ecosystem is used to illustrate how an ecosystem-level approach can be used to develop improved N management strategies. The N balance is used to demonstrate how nitrate in pumped groundwater used for crop irrigation could be used to reduce inputs of commercial fertilizer and decrease N leaching to aquifers. Effectively managing N pollution also will require an understanding of the complex factors that control the N balance, including targeted regulations, individual human behavior, land-use conversion, and other ecosystem management practices that affect the N balance. These sometimes countervailing factors are illustrated with several scenarios of wastewater treatment technology and population growth in the Phoenix area. Management of N eventually must be coupled to management of other elements, notably carbon, phosphorus, and salts. We postulate that an ecosystem framework for pollution management will result in strategies that are more effective, fairer, and less expensive than current approaches.

Open laparoscopic access using a radially dilating trocar: experience and indications in 50 consecutive cases.

BACKGROUND: Laparoscopy can be performed using needle access for initial insufflation or open access. PATIENTS AND METHODS: A technique for open laparoscopic access to the abdomen using a radially dilating cannula was used in 52 operations in 50 patients. Indications included age <2 years, severe kyphosis, and creation of an umbilical stoma. RESULTS: There was one case of minor leakage of carbon dioxide that did not affect the procedure being performed. There were two cases of preperitoneal placement, which were recognized immediately; in both, peritoneal access was easily obtained. CONCLUSION: Open laparoscopic access is safely and easily performed with a radially dilating trocar. This is the preferred technique at our institution for patients who meet the criteria for open access.

Radical bulbar dissection to correct severe chordee and proximal hypospadias.

PURPOSE: We describe a technique of proximal hypospadias correction that involves freeing the proximal normal bulbar urethra from perineal attachments to lengthen the ventral penis and decrease chordee. MATERIALS AND METHODS: Correction was performed in 9 patients with a mean age of 11.5 months who had proximal hypospadias and severe chordee that was perineal in 2, mid scrotal in 6 and penoscrotal in 1. After the penis was degloved the bulbar urethra was detethered to or beyond the perineal body without lifting the urethra from the corpora cavernosa. Any remaining penile chordee was corrected and the urethral plate was transected only when chordee persisted. When the urethral plate was intact and the penis straight, tubularized incised plate urethroplasty was done to correct hypospadias in 1 stage. Otherwise 2-stage repair was performed. RESULTS: Using this maneuver penile straightening was achieved in 2 of the 9 patients, resulting in a glanular urethral or penoscrotal meatus. Dorsal plication sutures required in 4 cases resulted in a mid shaft and penoscrotal meatus in 1 and 3, respectively. Residual chordee in the remaining 3 patients necessitated division of the urethral plate and 2-stage repair despite aggressive mobilization of the proximal urethra. Simultaneous tubularized incised plate urethroplasty was then performed in the 4 penoscrotal and 1 mid shaft meatus. All 6 patients who underwent a successful 1-stage procedure have excellent cosmetic results, while 1 required meatotomy. No fistula or chordee was present at a mean of 13.8 months of followup (range 3.9 to 27.1). CONCLUSIONS: This safe, rapid technique may compensate for significant penile tethering and chordee in a subpopulation of patients with proximal hypospadias, such as 6 of the 9 in our study. It also allows successful tubularized incised plate urethroplasty to be done simultaneously.

The modified Cantwell-Ransley repair for exstrophy and epispadias: 10-year experience.

PURPOSE: We evaluate our experience with the modified Cantwell-Ransley epispadias repair technique to determine the complications and long-term results. MATERIALS AND METHODS: The modified Cantwell-Ransley epispadias repair was performed during the last 10 years in 93 males of whom 79 had classic bladder exstrophy and 14 had complete epispadias. Primary repair was performed in 65 boys with classic bladder exstrophy and 12 with epispadias, and secondary repair was done after prior failed reconstruction in 14 boys with classic exstrophy and 2 with complete epispadias. RESULTS: At mean followup of 68 months 87 patients had a horizontal or downward angled penis while standing. The incidence of urethrocutaneous fistulas was 23% in the immediate postoperative period and 19% at 3 months. A urethral stricture at the proximal anastomotic area developed in 7 patients and 5 (4 with exstrophy and 1 with epispadias) had minor skin separations of the dorsal penile skin closure. Catheterization or cystoscopy in 77 cases revealed an easily negotiable neourethral channel. CONCLUSIONS: The modified Cantwell-Ransley epispadias repair produces an excellent functional and cosmetic result.

Tmp21-I, a vesicular trafficking protein, is differentially expressed during induction of the ureter and metanephros.

PURPOSE: To identify genes participating in the reciprocal induction of the metanephros and ureter. MATERIALS AND METHODS: Embryonic day 14 Sprague-Dawley rat kidneys and ureters were microdissected into differentiating mesenchyme, ureteric buds, and extrarenal ureter and prepared for RT/PCR differential display. Differentially displayed cDNAs were reamplified, cloned, and sequenced. Expression was verified in the embryonic, newborn or adult kidneys by Northern blot hybridization or RT/PCR using sequence specific primers. A newborn rat kidney cDNA library was prepared and screened with probes of interest. Positive clones were screened, sequenced and compared to the GenBank/EMBL databases. A rabbit polyclonal antibody was raised to a synthetic peptide of the Tmp21-I protein and was used for immunohistochemistry. RESULTS: From the cDNAs differentially displayed by the ureteric buds cDNA B11, is 254 bp in length. The gene for B11 is expressed in adult and newborn kidneys as two transcripts (3.4 kb and 1.3 kb). More importantly, RT/PCR on E14 kidneys using B11 sequence specific primers identified expression in the embryonic kidney at the beginning of induction. B11 cDNA library screening yielded clones with inserts of 1.3 kb. This sequence encodes Tmp21-I, a vesicular trafficking protein. Immunohistochemistry demonstrates that Tmp21-I is abundant in the nephrogenic cortex of the newborn kidney and as a nephron matures, the protein levels decline. The protein is essentially absent in the adult rat kidney. CONCLUSIONS: Tmp21-I is a developmentally regulated gene expressed during kidney induction. Localized within the nephrogenic zone, it may direct the intracellular trafficking or secretion of proteins responsible for nephrogenesis.