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Purpose: Identifying factors associated with emergency visits that could be delivered at lower cost sites may help guide population health strategies for pediatric patients with spina bifida., Materials and Methods: Emergency department encounters (2016-2023) by patients with spina bifida (younger than 18 years) in the Pediatric Health Information System were identified. Absence of clinical and imaging charges was defined as low-value emergency visit. We used a control population of patients (younger than 18 years) with obstructive/reflux uropathy who presented for emergency department encounters (2016-2023). Mixed-effects (with repeated individual measurements as random effect) logistic regression was fitted to model odds of low-value emergency visit., Results: In total, we included 22,672 emergency visits by patients with spina bifida. 20.7% of these emergency visits were low value vs 17.7% in controls ( P < .001). Costs related to low-value emergency visits account for 3.8% of all costs for emergency visit-related encounters in patients with spina bifida. Low-value emergency visits were associated with younger age (OR, 1.05 [1.04-1.06] per year younger), Hispanic/Latino ethnicity (OR, 1.21 [1.06-1.39] compared with non-Hispanics), Black race (OR, 1.35 [1.16-1.58] compared with White), public insurance (OR, 1.14 [1.01-1.29] compared with private insurance), and genitourinary encounter diagnosis (OR, 1.16 [1.04-1.30]). Using a standard patient, we found that the odds of low-value emergency visit across hospitals ranged from 0.31 to 5.36., Conclusions: Younger age, Hispanic/Latino ethnicity, Black and other race, public insurance, and genitourinary encounter diagnosis were associated with higher odds of low-value emergency visits in pediatric patients with spina bifida. There was wide variation across hospitals, which warrants further investigation to elucidate best practices.

Background: We aimed to determine if pre-existing immunocompromising conditions (ICCs) were associated with the presentation or outcome of patients with acute coronavirus disease 2019 (COVID-19) admitted for pediatric intensive care., Methods: Fifty-five hospitals in 30 US states reported cases through the Overcoming COVID-19 public health surveillance registry. Patients <21 years admitted 12 March 2020-30 December 2021 to the pediatric intensive care unit (PICU) or high-acuity unit for acute COVID-19 were included., Results: Of 1274 patients, 105 (8.2%) had an ICC, including 33 (31.4%) hematologic malignancies, 24 (22.9%) primary immunodeficiencies and disorders of hematopoietic cells, 19 (18.1%) nonmalignant organ failure with solid-organ transplantation, 16 (15.2%) solid tumors, and 13 (12.4%) autoimmune disorders. Patients with ICCs were older, had more underlying renal conditions, and had lower white blood cell and platelet counts than those without ICCs, but had similar clinical disease severity upon admission. In-hospital mortality from COVID-19 was higher (11.4% vs 4.6%, P = .005) and hospitalization was longer (P = .01) in patients with ICCs. New major morbidities upon discharge were not different between those with and without ICC (10.5% vs 13.9%, P = .40). In patients with ICCs, bacterial coinfection was more common in those with life-threatening COVID-19., Conclusions: In this national case series of patients <21 years of age with acute COVID-19 admitted for intensive care, existence of a prior ICCs were associated with worse clinical outcomes. Reassuringly, most patients with ICCs hospitalized in the PICU for severe acute COVID-19 survived and were discharged home without new severe morbidities., Competing Interests: Potential conflicts of interest. B. M. C. reports grants from NHLBI, American Lung Association, Doris Duke Foundation/Walder Foundation, and American Thoracic Society; payment for expert testimony from Tripplett Woolf Garretson; and participation on a multidisciplinary team for Sobi. N. B. H. reports grants from Sanofi, Quidel, and Merck. C. V. H. reports royalties, consulting fees, for Reviewer for Up To Date and Dynamed clinical databases; payment for presentations from Biofire; and expert consultation for the AstraZeneca FluMist Board. A. G. R. reports licenses as a Section Editor for Pediatric Critical Care Medicine, UpToDate, Inc; consulting fees from ThermoFisher, Inotrem; honoraria from a Grand Rounds presentation at St. Jude; support for meetings and/or travel from International Sepsis Forum, Institut Merieux, ThermoFisher; participation on an advisory board for the NIH Grace Study, REMAP-CAP, NIH-PREVENT-VILI; a medical advisory board member for Families Fighting Flu; chair member for International Sepsis Forum; and received reagents from Illumina, Inc. M. K. reports support for meetings and/or travel from the National Institute of Health (NIH) and a role on an advisory board for KultureCity. H. D. reports honoraria from Delex Pharma International, Inc. N. Z. C. reports grants from Cincinnati Children's Hospital Medical Center. J. C. F. reports grants from the National Institute of Diabetes and Digestive and Kidney Diseases (K23DK119463 and P50DK114786), and Pennsylvania CURE Grant. M. W. H. reports licenses from Kiadis, sub-board service for the American Board of Pediatrics, participation on a Data and Safety Monitoring Board (DSMB) for Abbvie, and receipt of drugs from Partner Therapeutics and Sobi. J. C. reports receipt of equipment from Illumina. B. L. reports receipt of an Immune Deficiency Foundation Research Grant. G. E. M. reports payment for expert testimony from Orlando Health, Bush Ross, Hall, Schiefflin & Smith, PA, Poole Brooks and Plumlee, PA, Hilltop Specialty Insurance, Smith, Hulsey, and Busey, PA. J. E. S. reports grants from the Food and Drug Administration (FDA), consulting fees from the Association for Professionals in Infection Control and Epidemiology (APIC), payment for presentations from the American Academy of Pediatrics, and participation on an advisory board for the American Association of Medical Colleges. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Vaginal reconstruction with autologous buccal mucosa graft offers a promising alternative to the use of skin grafts and vascularized intestinal segments. Given the novelty of this procedure, the optimal approach to postoperative wound management remains unclear with current practices often requiring many months of vaginal stents/molds. This study aims to evaluate a newly developed negative pressure intravaginal wound vacuum placed at the conclusion of the vaginoplasty with the goals of facilitating graft take and healing., Methods: A retrospective review of patients (age 12-21 years) who underwent eight primary and secondary vaginoplasty procedures using autologous buccal mucosa coupled with intravaginal wound vacuum placement was performed., Results: Vaginal reconstruction with fenestrated full-thickness buccal mucosa graft and intravaginal wound vacuum placement was successfully performed eight times in seven patients at a median age of 15.6 years. Four patients underwent robotic vaginal pull-through with buccal mucosa serving as an interposition graft, and four patients underwent vaginoplasty with buccal graft alone. All cases had excellent engraftment at time of wound vacuum removal on postoperative day seven and had healthy-appearing buccal mucosa at a mean follow-up of 148 days. Postoperatively, one patient developed a stricture at the anastomosis between native vagina and buccal mucosa graft, requiring a second buccal mucosa graft six months after the first operation., Conclusions: The use of autologous buccal mucosa graft for primary and secondary vaginal reconstruction coupled with intravaginal wound vacuum therapy offers a promising new approach. Negative pressure wound vacuum therapy may provide a more optimal wound healing environment for improved outcomes., Type of Study: Retrospective Study LEVELS OF EVIDENCE: Level IV., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Currently accepted primary repair of congenital anorectal malformations (ARMs) includes a posterior sagittal incision, which allows for optimal visualization and identification of important pelvic structures and anatomical features. Reconstructive surgery involves meticulous dissection and separation of pelvic structures, and careful reconstruction can result in good functional outcomes for many patients, who live without ongoing sequelae from their malformation. However, some patients may require reoperative procedures for anatomic or functional reasons. Males and females present with slightly different symptoms and should be approached differently. Males are most likely to require reoperations for anorectal or urethral pathologies, but the urinary system is often spared in females-they instead must contend with Mullerian duct anomalies, of which there are many varieties. Depending on the original malformation and severity of symptoms, redo surgery may be needed to optimize function and quality of life. Surgical management with reoperative surgery in ARMs ranges from straightforward to complex, depending on the issue. One must weigh the risks of reoperative surgery and potentially creating more scarring against the need for a better anatomical and functional outcome. Current management trends and practice patterns with regards to reoperative surgery in ARM patients are not widely studied or standardized but we provide an overview of the more common pathologies, preoperative evaluation and workup required to identify the issues, and options for reoperative repair in these patients., Competing Interests: Conflict of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/tgh-20-214). The series “Current Topics in Pediatric General Surgery” was commissioned by the editorial office without any funding or sponsorship. The authors have no other conflicts of interest to declare., (2021 Translational Gastroenterology and Hepatology. All rights reserved.)

Introduction: Understanding details of anatomic relationships between the colon and surrounding structures is a critical piece of preoperative planning prior to surgical repair of anorectal malformations (ARMs). Traditional imaging techniques involve ionizing radiation, distention of the rectum with supraphysiologic intraluminal pressures, and sometimes require sedation. Recent developments in the field of contrast agents have allowed the emergence of an ultrasound-based technique that can avoid these requirements while continuing to provide high resolution structural information in three dimensions., Methods: Fourteen children (13 male, 1 female, age 1-11 months) with ARMs underwent contrast enhanced colostography (ceCS) in addition to traditional preoperative imaging techniques to delineate anatomic relationships of pelvic structures., Results: ceCS and traditional imaging yielded concordant anatomic information, including structural relationships and fistulous connections, in 10/14 patients (71%). ceCS detected fistulous connection in 2/13 patients (15%) that were not seen by traditional imaging. Ultrasonography failed to detect the fistulous connection in one patient., Conclusions: ceCS is a safe, effective and flexible method for defining important structural information in ARM patients. When compared with traditional methods, it provided equivalent or superior results 93% of the time and bears consideration as a standard tool in preoperative planning for this population., Type of Study: Retrospective Comparative Study., Level of Evidence: Level III., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: During the COVID-19 crisis, there has been widespread reporting that non-COVID-19-related medical care has been delayed, even for emergent conditions. Testicular torsion is an emergent condition with higher risk of testicular loss with longer ischemic times. We sought to investigate whether patients with testicular torsion had longer time from symptom onset to initial presentation, longer total ischemic time, and higher rate of orchiectomy during the pandemic., Materials and Methods: Using billing data, we identified all patients age >1yo seen in our hospital from 1/1/2018 through 5/31/2020 who underwent emergent scrotal exploration for confirmed testicular torsion, comparing the COVID-19 crisis (3/1/2020-5/31/20) to the pre-COVID-19 period (1/1/2018-2/29/20). The primary outcome was time from symptom onset to initial presentation and secondary outcomes were ischemic time (time from symptom onset to entry of the OR) and orchiectomy rate. Parameters were compared with Mann-Whitney U and Fisher's exact tests; Poisson regression compared rates of torsion., Results: Of 94 total cases, 77 occurred during the pre-COVID-19 period and 17 during the COVID-19 crisis. Median time from symptom onset to initial presentation was not significantly different (2.4 h [IQR 1.1 h-38.9] during COVID-19 vs. 5.6 h [IQR 1.6-16.9] during pre-COVID-19 period, p = 0.476). Time to presentation was >12 h in 5/17 patients (29%) during COVID-19 and 24/77 patients (31%) during pre-COVID-19 period (p = 1.00). Median ischemic time during COVID-19 was 7.5 h (IQR 4.7 h-45.5 h) compared to 9.4 h (IQR 5.4 h-22.5 h) during pre-COVID-19 period (p = 0.694). Incidence of orchiectomy in our center was 29% (5/17) during COVID-19 and 17% (13/77) during pre-COVID-19 period (p = 0.397). About half of patients were seen initially at outside facilities prior to arrival (47% [8/17] during COVID-19 vs. 49% [38/77] during pre-COVID-19 period, p = 1.00). The number of torsion case presentations per week to our facility increased from 0.7 cases/week in the pre-COVID-19 period to 1.3 cases/week during COVID-19 (p = 0.015); when comparing only the March 1 to May 31 calendar period, there were 0.6 cases/week during the pre-COVID-19 period and 1.3 cases/week during COVID-19 (p = 0.021)., Conclusion: Time to presentation, ischemic times, and orchiectomy rates for testicular torsion at our center were not significantly different during the COVID-19 period compared to the preceding 2 year period. The number of torsion case per week presenting to our facility increased significantly., Competing Interests: Conflict of interest None., (Copyright © 2020 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Introduction: Cloaca malformation repair strategy is strongly dictated by common channel and urethral lengths. Mid to long common channel cloacas are challenging and often require laparotomy for dissection of pelvic structures. The balance of common channel and urethral lengths often dictates the approach for reconstruction. Laparoscopy has been utilized for rectal dissection but not for management of the urogenital (UG) structures. We hypothesized that laparoscopy could be applied to UG separation in reconstruction of cloaca malformations. Methods: Records were reviewed for 9 children with cloaca who underwent laparoscopic rectal mobilization and UG separation. Clinical parameters reviewed included demographics, relevant anatomic lengths, operative duration, transfusion requirements, and perioperative complications. Results: Repair was perfomed at a median (interquartile range) age of 12 (7, 15) months. Common channel length as measured by cystoscopy was 3.5 (3.3, 4.5) cm. There were no intraoperative complications. Transfusion requirements were minimal. Postoperative length of stay was 6 (5, 11) days. One patient developed a urethral web and 2 developed vaginal stenosis. One patient later underwent a laparotomy for obstruction due to a twisted rectal pull-through. Conclusions: Laparoscopic rectal mobilization and UG separation in long common channel cloaca are safe and well tolerated. Laparoscopy affords full evaluation of Mullerian structures and enables separation of the common UG wall, which may ultimately enhance long-term urinary continence.

Mabry syndrome is a glycophosphatidylinositol (GPI) deficiency characterized by intellectual disability, distinctive facial features, intractable seizures, and hyperphosphatasia. We expand the phenotypic spectrum of inherited GPI deficiencies with novel bi-allelic phosphatidylinositol glycan anchor biosynthesis class O (PIGO) variants in a neonate who presented with intractable epilepsy and complex gastrointestinal and urogenital malformations., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Purpose To retrospectively define the strength of association between testicular microlithiasis and testicular neoplasia in a large geographically diverse pediatric population. Materials and Methods Retrospective review of scrotal ultrasonographic (US) examination reports and pathology specimens obtained between January 2000 and May 2014 at six academic pediatric hospitals in North America was performed. Reported cases were reviewed to confirm microlithiasis. Radiology and pathology data bases were searched for pathology-proven testicular tumors (benign or malignant germ cell or stromal tumors). Association strength (risk) was expressed in terms of odds ratios (ORs) with and without adjustment for fixed study site effects based on logistic regression. Results A total of 37 863 individuals underwent scrotal US during the study period. Mean age was 11.1 years ± 4.7 [standard deviation] in boys with microlithiasis and 9.1 years ± 5.9 in boys without microlithiasis (P < .001). Microlithiasis was confirmed in 2.90% of patients (1097 of 37 863; range, 1.61%-5.25% across sites). It was unilateral in 21.97% (241 of 1097) of patients and bilateral in 78.0% (856 of 1097). Tumor was identified in 4.64% (51 of 1097) of boys with microlithiasis and 0.33% (122 of 36 766) of boys without (unadjusted OR, 14.65; 95% confidence interval [CI]: 10.29, 20.84; adjusted OR, 14.19). Malignant germ cell tumors were identified in 2.8% (31 of 1097) of boys with microlithiasis and 0.12% (45 of 36 766) of boys without microlithiasis (unadjusted OR, 17.26; 95% CI: 11.8, 25.25; adjusted OR, 22.37). Sex cord-stromal tumors were identified in 0.46% (five of 1097) of boys with microlithiasis and 0.079% (29 of 36 766) of boys without (unadjusted OR, 5.8; 95% CI: 2.1, 16; adjusted OR, 6.39). Conclusion There is a strong association between testicular microlithiasis and primary testicular neoplasia in this pediatric population. © RSNA, 2017.

Disorders of sex development are challenging to evaluate and diagnose in the newborn. As pediatric urologists, our goals are to (1) identify patients who should be evaluated; (2) rule out life-threatening syndromes; and (3) involve a multidisciplinary team for evaluation, diagnosis, and gender assignment. This review briefly goes over the newborn differential diagnosis in disorders of sex development, highlights the important laboratory and imaging data needed, and discusses the multidisciplinary approach to gender assignment and care of these patients. Early involvement of the family in decision-making with the multidisciplinary team is paramount to a timely evaluation and diagnosis in these patients., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Pompe disease (PD) is a disorder of lysosomal glycogen storage. The introduction of enzyme replacement therapy (ERT) has shifted the focus of care from survival to quality of life. The presence of lower urinary tract symptoms (LUTS) and incontinence has not been previously described in children with PD., Methods: Children with PD followed in the Duke Lysosomal Storage Disease Clinic completed a validated bladder control symptom score (BCSS) and additional questions regarding urinary tract infections (UTIs), giggle, and stress incontinence. Descriptive statistics were used to discriminate urinary symptoms between gender, age, and different types of PD., Results: Sixteen of 23 children (aged 4-14 years) seen in our clinic participated. Seven were girls; ten had classic infantile PD, two atypical infantile PD, and four childhood presentation late-onset PD (LOPD). When stratified by PD subtype, median BCSS was worst for the classic PD subtype followed by atypical PD and LOPD. Daytime urinary incontinence accompanied by constipation was noted in six. Eight reported urinary incontinence with laughing: giggle incontinence in six and stress incontinence in two. Four girls reported a history of UTI. Longitudinal follow-up in 11 patients showed stable BCSS in six, improvement in three, and worsening in two. Worsening corresponded with changes in bowel function and improvement with increase in ERT dose or treatment of constipation., Conclusions: LUTS and incontinence are common in children with PD with greater symptoms noted with infantile-type PD. Improved bowel function and increase in ERT dose may lead to improvements in BCSS.

Purpose: We describe our experience with 2-stage proximal hypospadias repair. We report outcomes, and patient and procedure characteristics associated with surgical complications., Materials and Methods: We retrospectively studied patients with proximal hypospadias who underwent staged repair between January 1993 and December 2012. Demographics, preoperative management and operative technique were reviewed. Complications included glans dehiscence, fistula, meatal stenosis, nonmeatal stricture, urethrocele/diverticula and residual chordee. Cox proportional hazards model was used to evaluate the associations between time to surgery for complications and patient and procedure level factors., Results: A total of 134 patients were included. Median patient age was 8.8 months at first stage surgery and 17.1 months at second stage surgery, and median time between surgeries was 8 months. Median followup was 3.8 years. Complications were seen in 71 patients (53%), with the most common being fistula (39 patients, 29.1%). Reoperation was performed in 66 patients (49%). Median time from urethroplasty to surgery for complication was 14.9 months. Use of preoperative testosterone decreased risk of undergoing surgery for complication by 27% (HR 0.73, 95% CI 0.55-0.98, p = 0.04). In addition, patients identified as Hispanic were at increased risk for undergoing surgery for complications (HR 2.40, 95% CI 1.28-4.53, p = 0.01)., Conclusions: We review the largest cohort of patients undergoing 2-stage hypospadias repair at a single institution. Complications and reoperation rates were approximately 50% in the setting of complex genital reconstruction., (Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Introduction: Augmentation enterocystoplasty and appendicovesicostomy are complex pediatric urologic procedures. Although there is literature identifying long-term outcomes in these patients, the reporting of short-term postoperative outcomes has been limited by small numbers of cases and lack of prospective data collection. Here we report 30-day outcomes from the first nationally based, prospectively assembled cohort of pediatric patients undergoing these procedures., Objective: To determine 30-day complication, readmission and reoperation after augmentation enterocystoplasty and appendicovesicostomy in a large national sample of pediatric patients, and to explore the association between preoperative and intraoperative characteristics and occurrence of any 30-day event., Study Design: We queried the 2012 and 2013 American College of Surgeons National Surgical Quality Improvement Program Pediatric database (ACS-NSQIPP) for all patients undergoing augmentation enterocystoplasty and/or appendicovesicostomy. Surgical risk score was classified on a linear scale using a validated pediatric-specific comorbidity score. Intraoperative characteristics and postoperative 30-day events were reported from prospectively collected data. A composite measure of complication, readmission and/or reoperation was used as primary outcome for the multivariate logistic regression., Results: There were 461 patients included in the analysis: 245 had appendicovesicostomy, 97 had augmentation enterocystoplasty and 119 had both procedures. There were a total of 110 NSQIP complications seen in 87 patients. The most common complication was urinary tract infection (see Table for 30-day outcomes by patient). The composite measure of any 30-day event was seen in 27.8% of the cohort and this was associated with longer operative time, increased number of procedures done at time of primary surgical procedure and higher surgical risk score., Discussion: The ACS-NSQIPP provides a tool to examine short-term outcomes for these complex urologic procedures that has not been possible before. Although ACS-NSQIP has been used extensively in the adult surgical literature to identify rates of complications, and to determine predictors of readmission and adverse events, its use in pediatric surgery is new. As in the adult literature, the goal is for standardization of practice and transparency in reporting outcomes that may lead to reduction in morbidity and mortality., Conclusion: In this cohort, any 30-day event is seen in almost 30% of the patients undergoing these urologic procedures. Operative time, number of concurrent procedures and higher surgical risk score all are associated with higher odds of the composite 30-day event of complication, readmission and/or reoperation. These data can be useful in counseling patients and families about expectations around surgery and in improving outcomes., (Copyright © 2015 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Elevated body mass index (BMI) is a well-known risk factor for perioperative complications in adults, but has not been investigated in children undergoing urologic procedures. Given the low rate of complications associated with urologic surgery, a large sample is required for their characterization, but BMI is frequently not available in administrative databases. Here we report results from the first nationally based, prospectively assembled cohort analyzed with respect to the association of BMI with 30-day postoperative events for pediatric urologic procedures., Objective: To determine the association of elevated BMI with overall 30-day postoperative events and wound complications in a large national sample of children undergoing urologic procedures., Study Design: We queried the 2012 Pediatric National Surgical Quality Improvement Program database (NSQIP), defining obesity as a BMI above the 95th percentile and overweight above the 85th percentile, per CDC definitions. We used BMI <85th percentile as a referent group. Complications were collected within 30 days of the procedure. Comorbidity was classified on a linear scale using a validated pediatric-specific comorbidity score, and procedures were classified as genital, abdominal without bowel involvement, or abdominal with bowel involvement. Univariate and multivariate logistic models were used to test significance of associations., Results: 2871 patients aged 2-18 years were analyzed. Of these, 420 (14.6%) were overweight and 440 (15.3%) were obese. A summary of 30-day events and complications is shown in the structured abstract table. On multivariate analysis adjusting for age, gender, class of procedure, and comorbidity, BMI remained a significant risk factor for 30-day events when comparing BMI ≥85th percentile to BMI <85th percentile (OR 1.36, 95% CI 1.03-1.8, p = 0.035). An exploratory subgroup analysis examining the rate of wound complications demonstrated an odds ratio of 2.36 (95% CI 1.28-4.35, p = 0.006) for BMI >85th percentile on multivariate analysis., Discussion: Overweight/obese status increased the odds of overall complications by 36%, and of wound complications by 140%. In adults there is a known profound effect of body composition on wound complications, but in children this association is less clear, and has not been studied in the pediatric urologic literature on a large scale. The mechanisms linking BMI to pediatric postoperative complications are unclear, but cytokine mechanisms or changes in the response to inflammation have been postulated. Limitations of this study include restriction to those urologic procedures included in ACS-NSQIPP and sorted into broad general categories. We did not control for secondary procedures. BMI/BMI percentile may not be appropriate measures of body composition in patients with atypical body habitus or proportions (e.g. myelomeningocele)., Conclusion: BMI in the pediatric NSQIP urologic population was found to be associated with overall complication after adjustment for case type and preoperative comorbidity in a large national sample assembled for assessment of perioperative outcomes. An exploratory analysis uncovered more than two-fold increase in odds of wound complication in obese/overweight patients compared with a normal weight referent population. These results may be useful in preoperative counseling patients regarding perioperative risk., (Copyright © 2015 Journal of Pediatric Urology Company. All rights reserved.)

Objective: To study the prevalence of lower urinary tract symptoms (LUTS) and incontinence in late-onset Pompe disease (LOPD) Methods: Adult LOPD patients seen at the Duke Pompe Clinic were prospectively recruited and asked to complete validated questionnaires on LUTS and incontinence as part of an IRB-approved study. Patient demographics as well as previous urologic history were reviewed., Results: 35 patients with LOPD were included in the study (17 males and 18 females). The median age was 51.8 (range 18-72 years of age). Of these patients, 27/35 were receiving enzyme replacement therapy (ERT) with median duration of 54 months (range 5-88 months). In the male patients, 9/17 (53%) described their stream as dribbling, weak, or intermittent, and 9/17 (53%) complained of post-void dribbling. In addition 38% of the men were unable to stop their urination midstream. In the female patients, the most common complaint was urinary incontinence, reported in 14/18 (78%). In addition, 7/18 (39%) complained of post-void dribbling, and 47% were unable to stop their urination midstream. Bowel incontinence was reported in 45% of patients. There was a significant association between urinary symptoms and lower extremity function scores and duration of ERT (p = 0.005 and p = 0.04, respectively), Conclusions: This is the first study in a large cohort of LOPD patients that demonstrates LUTS and incontinence occur at a high rate. This study emphasizes the spectrum of LOPD is beyond isolated gross motor and pulmonary involvement and has a significant effect on the lower urinary tract.

Neuronopathic Gaucher disease can present as a continuum of clinical findings, including somatic symptoms of anemia, thrombocytopenia, hepatosplenomegaly, and bone disease as well as neurologic sequelae. There is a spectrum of neurologic symptoms ranging from oculomotor apraxia to severe convulsions. The heterozygosity of phenotypes makes it difficult to predict the disease course. We describe an 8-year-old male with neuronopathic type III Gaucher disease who developed bladder dysfunction and was unable to completely void. He also presented with hypertension and acute renal insufficiency, most likely secondary to urinary retention. A complete evaluation was done for causes of urinary retention and bladder dysfunction. A renal bladder ultrasound demonstrated marked hydroureteronephrosis. There was no clinical evidence of infection and cystoscopy revealed no anatomic obstruction. In addition, MRI showed no spinal abnormalities. His bladder dysfunction was managed operatively by creating a catheterizable stoma, using his appendix, to empty his bladder, and surgical findings were consistent with neurogenic bladder. He continues to be managed for his Gaucher disease and neurogenic bladder by genetics, nephrology and urology. This is the first clinical report of neurogenic bladder dysfunction in neuronopathic Gaucher disease.

Objective: We hypothesized that cold ischemia during partial orchiectomy would lead to higher serum testosterone levels and preservation of testicular architecture than warm ischemia in a prepubescent rat model., Materials and Methods: Eighteen prepubescent male Sprague-Dawley rats were randomized to three different surgical groups: sham surgery, bilateral partial orchiectomy with 30 min of cord compression with cold ischemia, or bilateral partial orchiectomy with 30 min of cord compression with warm ischemia. Animals were killed at puberty, and serum, sperm, and testicles were collected. Histological tissue injury was graded by standardized methodology., Results: Mean serum testosterone levels were 1445 ± 590 pg/mL for the sham group, 449 ± 268 pg/mL for the cold ischemia group and 879 ± 631 pg/mL for the warm ischemia group (p = 0.12). Mean sperm counts were 2.1 × 10(7) for sham, 4.4 × 10(6) for cold ischemia, and 9.9 × 10(6) for the warm ischemia groups (p = 0.48). Histological evaluation revealed significant difference in tissue injury grading with more injury in the cold ischemia than in the warm ischemia group (p = 0.01)., Conclusions: In our preclinical rat model, we found no benefit for cold ischemia over warm ischemia at 30 min., (Copyright © 2014 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Objective: Diagnosis of low-grade hydronephrosis often occurs prenatally, during evaluation after urinary tract infection (UTI), or imaging for non-urologic reasons within the first year of life. Its significance in terms of resolution, need for antibiotic prophylaxis, or progression to surgery remains uncertain. We hypothesized that isolated low-grade hydronephrosis in this population frequently resolves, UTIs are infrequent, and progression to surgical intervention is minimal., Patients and Methods: Children < 12 months old diagnosed hydronephrosis (Society for Fetal Urology [SFU] grade 1 or 2) between January 2004 and December 2009 were identified by ICD9 code. Patients with other urological abnormalities were excluded. Stability of hydronephrosis, UTI (≥ 100,000 CFU/mL bacterial growth) or need for surgical intervention was noted., Results: Of 1496 infants with hydronephrosis, 416 (623 renal units) met inclusion criteria. Of 398 renal units with grade 1 hydronephrosis, 385 (96.7%) resolved or remained stable. Only 13 (3.3%) worsened, of which one underwent ureteroneocystostomy. Of 225 renal units with grade 2 hydronephrosis, 222 (98.7%) resolved, improved or remained stable, three (1.3%) worsened, of which one required pyeloplasty. Only 0.7% of patients in the ambulatory setting had a febrile UTI., Conclusions: Low-grade hydronephrosis diagnosed within the first year of life remains stable or improves in 97.4% of renal units. Given the low rate of recurrent UTI in the ambulatory setting, antibiotic prophylaxis has a limited role in management., (Copyright © 2014. Published by Elsevier Ltd.)

Objective: To describe our experience with the UroLume Urethral Stent, showing that it provides a viable option for the devastated, obstructed outlet after prostate cancer treatment., Methods: We conducted an institutional review board-approved retrospective study of all men at our facility who underwent placement of the UroLume stent from January 2001 to January 2012. Records were reviewed for patient demographics, outcomes, and complications. We specifically evaluated urinary continence, ingrowth of the UroLume stent, need for repeat operations, and complications related to this treatment including artificial urinary sphincter (AUS) erosion., Results: Forty-five men underwent placement of the UroLume stent with an average follow-up of 55.8 months. Of these, 41 had simultaneous or subsequent placement of an AUS with an overall continence rate of 35 of 45 (78%). Ingrowth was seen in 16 of 45 (36%) and AUS erosion in 8 of 41 (19.5%). Of the 16 patients treated for ingrowth, the average number of treatments was 2.7 per patient. There was no association between treatment for ingrowth and rate of AUS erosion (P = .92)., Conclusion: Although no longer commercially available, our long-term data indicate that the UroLume was a reasonable minimally invasive treatment option for the devastated, obstructed outlet providing a reasonable rate of need for subsequent interventions. The UroLume maintains patency of the urethral lumen, which usually results in incontinence, but this can be managed with placement of the AUS. The alternative open operative reconstructive options have similar limitations with possibly greater morbidity., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: Urinary tract infections (UTIs) are a common source of morbidity among children with spina bifida (SB) and are a frequently reported outcome in studies of this patient population. However, the criteria for a diagnosis of UTI are often not stated. We evaluated the literature on SB patients for the criteria that authors use to define parameters in reporting UTI outcomes., Methods: Embase and Medline were queried with the medical subject heading terms “spinal dysraphism,” “myelomeningocele,” “infection,”and “urinary tract infection.” A second search with the exploded term“spina bifida” and “urinary tract infection” was performed. Original research studies reporting a UTI outcome in SB patients were included and evaluated by 2 independent reviewers for the presence of a UTI definition and diagnostic criteria., Results: We identified 872 publications, of which 124 met inclusion criteria. Forty-five of 124 (36.3%) studies reporting UTI as an outcome provided a definition of UTI. Of 124 studies, 28 (22.6%) were published in pediatric journals and 69 (55.6%) in urology journals. A definition of UTI was provided in 11 (39.3%) and 26 (37.7%) studies, respectively. “Fever,culture, and symptoms” defined a UTI in 17 of 45 studies. Journal category and presence of UTI definitions did not correlate (P = .71)., Conclusions: Explicit definitions for UTI are heterogeneous and infrequently applied in studies of SB patients, limiting study reliability and estimates of true UTI rates in this population. Future studies will benefit from the development and application of a standard definition for UTI in this population.

Introduction: Systematic reviews and meta-analyses of well-designed and executed randomized controlled trials have the potential to provide the highest levels of evidence to support diagnostic and therapeutic interventions in urology., Materials and Methods: The role of systematic reviews in the urological literature is described. A three-step appraisal of the validity, magnitude and applicability of results will permit an evidence-based approach to incorporating findings of systematic reviews and meta-analyses into practice., Results: The validity of systematic reviews depends on a focused clinical question that generates specific inclusion and exclusion criteria for identifying studies through an exhaustive literature search. The primary studies must be of high methodological quality and assessments should be reproducible. Informed consumers of the urological literature should be aware of the consistency of results between trials in a review, as well as the magnitude and precision of the best estimate of the treatment effects. When making decisions about implementing the results, urologists should consider all patient-important outcomes, the overall quality of the evidence and the balance between benefits, potential harms and costs., Conclusion: This framework will lead to a more evidence-based application of systematic reviews within the urological literature. Ideally, utilization of an evidence-based approach to systematic reviews will improve the quality of urological patient care.

Erectile dysfunction is defined as the consistent or recurrent inability to attain or maintain penile erection sufficient for sexual performance. Self-reported erectile dysfunction has increased significantly as men seek effective therapy, such as oral phosphodiesterase 5 inhibitors (PDE5i). PDE5i are now the drugs of choice in the initial therapy of erectile dysfunction. This review compares the currently available PDE5i with the second-generation PDE5i, which are soon to be available., (2011 Elsevier Ltd. All rights reserved.)

Outer membrane protein E (OMP E) is a 50-kDa protein of Moraxella catarrhalis which has several features that suggest that the protein may be an effective vaccine antigen. To assess the conservation of OMP E among strains of M. catarrhalis, 22 isolates were studied with eight monoclonal antibodies which recognize epitopes on different regions of the protein. Eighteen of 22 strains were reactive with all eight antibodies. The sequences of ompE from 16 strains of M. catarrhalis were determined, including the 4 strains which were nonreactive with selected monoclonal antibodies. Analysis of sequences indicate a high degree of conservation among strains, with sequence differences clustered in limited regions of the gene. To assess the stability of ompE during colonization of the human respiratory tract, the sequences of ompE of isolates collected from patients colonized with the same strain for 3 to 9 months were determined. The sequences remained unchanged. These results indicate that OMP E is highly conserved among strains of M. catarrhalis, and preliminary studies indicate that the gene which encodes OMP E remains stable during colonization of the human respiratory tract.

The bioequivalence of a proprietary liquid dapsone preparation and commercially available dapsone tablets was studied. Twelve adult volunteers received dapsone doses with 8 oz of water one to two hours after their usual breakfast. Each subject received an initial 100-mg dose of a propylene glycol-based liquid preparation of dapsone and, two weeks later, a 100-mg dapsone tablet (both from Jacobus Pharmaceutical Company, Princeton, NJ). Blood samples were collected before and at intervals up to 96 hours after the administration of each dose. Serum dapsone concentrations were determined by high-performance liquid chromatography, and pharmacokinetic values were calculated by model-independent analysis. The area under the concentration-versus-time curve and the maximum serum concentration for the two formulations met the criteria for bioequivalence. Time to maximum serum concentration tended to be lower for the liquid, but not significantly. The liquid and tablet formulations of dapsone studied were found to be bioequivalent and may be used interchangeably.

We compared responses to pneumococcal conjugate and polysaccharide vaccines in 48 otitis-free and 64 otitis-prone children. Pre- and postimmunization concentrations of antibodies to pneumococcal serotypes 6B, 14, 19F, and 23F were measured by enzyme-linked immunosorbent assay. Postimmunization mean concentrations of antibodies to all four serotypes were significantly higher for children receiving conjugate vaccine than for those receiving polysaccharide vaccine; the difference in responses was primarily due to a better response to conjugate vaccine in the otitis-prone group. Significantly higher postimmunization concentrations of antibodies to all four serotypes and to one of the four serotypes were found in otitis-prone children and otitis-free children who received conjugate vaccine, respectively. Pneumococcal conjugate vaccine has the potential to reduce the incidence of disease due to vaccine serotypes, even among children with recurrent otitis media.

The distal inner medullary collecting duct (IMCD) is critical in the urinary concentrating process, in part because it is the site of vasopressin (AVP)-regulated permeability to urea. The purpose of these experiments was to develop a cell culture model of the IMCD on permeable structure and to characterize the responsiveness to AVP. Rat IMCD cells were grown to confluence on collagen-coated Millipore filters glued onto plastic rings. To assess the time required to achieve confluence, the transepithelial resistance was measured periodically and was found to be stable after 2 weeks, at a maximal value of 595 +/- 22 omega cm2. In separate monolayers the effect of AVP on inulin and urea permeability was determined. While inulin permeability was unchanged after AVP, urea permeability increased from 6.0 +/- 0.4 to peak values of 16.0 +/- 3.8 (10 nM), 23.1 +/- 3.9 (1 microM) and 28.1 +/- 4.9 (10 microM) x 10(-6) cm s-1 (n = 24). In 10 other monolayers, after the addition of 1 mM 8-Br-cAMP, urea permeability increased from 5.1 +/- 0.3 to 8.1 +/- 1.6 x 10(-6) cm s-1 and, after 8-Br-cAMP + 3-isobutyl-1-methylxanthine, to 12.2 +/- 0.7 x 10(-6) cm s-1. We conclude that rat IMCD cells grown in culture exhibit the characteristics of a 'tight' epithelium. Inulin and urea permeability are not different in the absence of AVP, consistent with high resistance junctional complexes. Furthermore, IMCD cells retain the capacity for AVP-regulated urea permeability, a characteristic feature of this nephron segment in vivo.

The effect of the absence of parathyroid hormone on nephron acidification was determined in rats after acute thyroparathyroidectomy (TPTX). Tubular fluid samples were obtained from the superficial late proximal tubule (LPT), the early distal tubule ( EDT ), and along the inner medullary collecting duct (IMCD), and the results were compared with those obtained from control rats. In the LPT after TPTX, pH was lower, 6.66 +/- 0.01 vs. 6.73 +/- 0.01, and ammonium and net acid delivery were increased significantly. In the EDT no differences in pH, bicarbonate, or net acid were found between groups, whereas ammonium and acid phosphate were significantly different. Along the IMCD in control rats, pH decreased from 6.58 to 5.21 and the addition of about 430 nmol/min of net acid was observed. After TPTX more net acid entered the duct and pH was lower, 5.66, but did not change; neither did the amount of bicarbonate, ammonium, acid phosphate, or net acid change significantly along the duct. Net acid excretion was not different, however, among groups. These results demonstrate that TPTX markedly affects nephron acidification, increasing net acid along the proximal tubule. In contrast to that in control rats, however, net acidification is completed prior to the IMCD. We conclude that the acute absence of parathyroid hormone may significantly affect local nephron acidification but does not alter acid excretion.

Young (3 to 4 months) and old (21 to 22 months) rats were fed either a regular or high potassium (K) diet. After acute potassium chloride infusion, the fraction of infused K excreted (K efficiency) was similar in rats on a normal diet (57 +/- 3%, young, vs. 61 +/- 2%, old). With high K feeding there was a significant increase in the young, 69 +/- 4%, but not in the old rats, 62 +/- 2%. Na-K ATPase activity was markedly reduced in the renal medulla of old rats on a regular or high K diet. In addition, the response to acute K loading was compared in acutely nephrectomized rats. In the young rats on a regular diet plasma K increased from 3.72 +/- 0.09 to 5.28 +/- 0.16 mEq/liter while with K ingestion the increase was significantly less, 3.62 +/- 0.07 to 4.75 +/- 0.12 mEq/liter. In the old rats plasma K increased similarly on a regular or high K diet, 3.68 +/- 0.10 to 5.68 +/- 0.33 mEq/liter and 3.76 +/- 0.06 to 5.97 +/- 0.30 mEq/liter, respectively. Thus, old rats have impaired renal and extrarenal adaptation, but they have a normal response to an acute K challenge. A reduction in Na-K ATPase may account for the defect in renal adaptation in the aged rats.

The inner medullary collecting duct (IMCD) of the rat is a major site of acidification. However, previous micropuncture studies have failed to demonstrate acidification along the terminal IMCD during chronic acid feeding. To more completely evaluate this question we used the microcatheterization method in rats fed ammonium chloride for 3-7 days. Arterial pH was 7.30 +/- 0.015, and PCO2 was set at 40 +/- 0.6 mmHg. The IMCD data were analyzed as a function of IMCD length between 40% and the tip. Equilibrium pH decreased from 6.21 +/- 0.11 to 5.47 +/- 0.03, whereas PCO2 was unchanged (28 +/- 1 mmHg between the deep samples and tip). Bicarbonate delivery decreased from 92 +/- 14 to 10 +/- 1 nmol/min, titratable acid increased from 462 +/- 33 to 762 +/- 40 nmol/min, and ammonium delivery increased from 2,235 +/- 121 to 3,528 +/- 140 nmol/min. Thus estimated net acid increased from 2,638 +/- 134 to 4,303 +/- 161 nmol/min. To determine whether increasing delivery of buffer to the IMCD would stimulate acid secretion in acute acidosis, rats were studied during the infusion of HCl and creatinine. Arterial pH was 7.18 +/- 0.02. IMCD acidification was not increased compared with our previously published studies during HCl infusion [Am. J. Physiol. 241 (Renal Fluid Electrolyte Physiol. 10): F669-F676, 1981]. We conclude that chronic ammonium chloride ingestion stimulates IMCD acidification and that this increase may be an intrinsic modification of the acidification mechanism of the IMCD.

Tubular handling of potassium was studied in the Charles River CD (cesarean derived) rat by clearance, micropuncture, and anatomic techniques. The following groups were evaluated: group I, hydropenia; group II, KCl-mannitol infusion; group III, 10% body wt saline loading; group IV, uninephrectomy, hydropenia; and group V, uninephrectomy, saline loading. Comparison of micropuncture samples from early and late distal collection sites (LDCS) and urine collections revealed no net K transport along the distal convoluted tubule in groups I and III-V but net addition of K in all groups beyond the LDCS. Absolute K secretion beyond the LDCS appeared to be flow dependent in groups I-III. The LDCS was noted by light and electron microscopy always to be lined with collecting tubule epithelium. We conclude that no net change in potassium transport occurs along the superficial distal convoluted tubule during hydropenia or saline loading in normal or uninephrectomized Charles River CD rats, but secretion is demonstrable during KCl infusion. Net addition of potassium beyond the LDCS was noted in all groups and this addition was enhanced by uninephrectomy.

The purpose of these experiments was to evaluate the effect of acute respiratory alkalosis (ARA) and chronic bicarbonate drinking (CBD) on inner medullary collecting duct (IMCD) acidification. Microcatheterization was used to measure pH and PCO2, and samples were simultaneously obtained for measurement of bicarbonate, titratable acid (TA), and ammonium. In ten ARA rats (arterial pH was 7.54 +/- 0.02; PCO2 was 20 +/- 1 mmHg), IMCD equilibrium pH was not different (deep pH was 5.65 +/- 0.06 and PCO2 was 20 +/- 1 mmHg; tip pH was 5.54 +/- 0.07 and PCO2 was 22 +/- 1 mmHg). Delivery of bicarbonate, TA, and ammonium also did not differ between collection sites. Thus net acidification along the IMCD was negligible. Nine rats drank NaHCO3 for 5-8 days (pH = 7.48 +/- 0.02) but did not receive NaHCO3 during the experiment so that arterial pH fell to 7.40 +/- 0.01. IMCD equilibrium pH was different at deep (pH was 5.68 +/- 0.06; PCO2 was 32 +/- 1 mmHg) and tip (pH was 5.57 +/- 0.04; PCO2 was 27 +/- 1 mmHg; P less than or equal to 0.05) collection sites. However, only minimal changes in the delivery of bicarbonate, TA, and ammonium were noted, and net acidification along the IMCD was negligible. In ten control rats, net acidification was 219 nmol/min between collection sites (P less than 0.001). We conclude that ARA and CBD abolish acidification along the IMCD. In addition, CBD produces an intrinsic modification along the IMCD, which suppresses acid secretion and persists after acute recovery from alkalemia.

We previously reported that acute respiratory acidosis (ARA) did not stimulate inner medullary collecting duct (IMCD) acidification. It was possible that the failure to find enhanced IMCD acidification was a function of insufficient buffer delivery. To answer this question we studied IMCD acidification in rats with ARA during the infusion of the buffer creatinine. We employed the microcatheterization technique to directly measure pH and PCO2 with glass membrane electrodes and also obtained fluid samples for the measurement of titratable acid and ammonium. Arterial pH was 7.19 +/- 0.01 and PCO2 was 93 +/- 2 mmHg. The IMCD data were analyzed as a function of IMCD length (approximately 6 mm). Equilibrium pH decreased from 5.99 +/- 0.05 to 5.58 +/- 0.02 and PCO2 increased from 71 +/- 11 to 132 +/- 6 mmHg between origin and tip. Bicarbonate delivery decreased from 111 +/- 14 to 38 +/- 2 nmol/min; titratable acid increased from 867 +/- 87 to 1,625 +/- 61 nmol/min, but ammonium delivery did not change along the duct. Thus, estimated net acid increased from 1,772 +/- 155 to 2,709 +/- 88 nmol/min. We conclude that during the presence of increased buffer delivery to the IMCD, rats with ARA markedly increased proton secretion along the terminal nephron.

Potassium transport along the inner medullary collecting duct (IMCD) was evaluated by the microcatheterization technique in Charles River CD (cesarean derived) rats 7-9 days after sham operation (S) or uninephrectomy (UNPX). The fraction of filtered potassium (TF/P)K/In) as a function of IMCD length was analyzed by linear regression. In 13 S rats there was a significant correlation and slope (P less than 0.001) and (TF/P)K/In increased from 14% at the beginning of the IMCD to 25% in the urine. IMCD potassium secretion accounted for about half of the excreted potassium. In the UNPX rats a significant correlation and slope was also obtained (P less than 0.001); (TF/P)K/In at the beginning of IMCD was 24% and increased to 36% in the urine. No difference in slope was noted between the groups. There was a slightly greater absolute potassium secretion after UNPX (0.77 +/- 0.03 S vs. 0.93 +/- 0.04 mueq/min UNPX), but this did not account for most of the difference in potassium excretion noted. We conclude that net potassium secretion occurs along the IMCD in S and UNPX rats. After UNPX, there is significantly greater potassium delivery to the IMCD and a greater kaluresis. The increased kaluresis cannot be accounted for primarily by increased potassium secretion along the IMCD.

After adrenal enucleation, rats have an impaired ability to excrete a salt load because of enhanced collecting duct reabsorption. This antinatriuretic effect, thought to be secondary to a mineralocorticoid-like substance secreted by the enucleate gland, can be reversed by treatment with spironolactone or dexamethasone. To define the renal mechanisms involved in this drug-induced natriuresis we have utilized clearance and micropuncture techniques in enucleate saline-expanded rats that were treated with either spironolactone (S) or dexamethasone (D), or were untreated (U). Sodium excretion was clearly increased after S, 13.9, and D, 19.3 mueq/min vs. u, 5.9 mueq/min. The mechanisms of this natriuresis, however, were dissimilar. Spironolactone-treated rats were not different from untreated rats except with regard to function beyond the superficial late distal tubule, where U rats reabsorbed over 50% of the delivered sodium. In the S group 38% of the excreted sodium was added along this tubular locus, 5.2% of the filtered sodium reaching the late distal tubule and 7.3% appearing in the urine. These data demonstrate that the natriuresis after S is secondary to the net addition of sodium beyond the superficial late distal tubule. Spironolactone may work by inhibiting a mineralocorticoid-like product of the enucleate gland and, thereby, eliminate the sodium-retaining effect of this product. The natriuresis after D, however, can be explained solely on the basis of a markedly increased filtered load of sodium traversing the nephron.

Rats, made acidemic when fed NH4Cl, become alkalemic with discontinuation of the NH4Cl. This phenomenon has been called rebound metabolic alkalemia (RMA). This study examines the function of the inner medullary collecting duct (IMCD) during RMA. Rats drank only 1.5% NH4Cl for 5 days and then water for 16 h prior to study, yielding an arterial pH = 7.50 +/- 0.01, PCO2 = 39 +/- 1 mmHg, and bicarbonate = 29.5 +/- 1.0 mM. The IMCD data were obtained by microcatheterization from deep (1.5-3.0 mm) and tip (0.2-0.5 mm) samples. Equilibrium pH decreased from 5.92 +/- 0.09 (n = 20) to 5.38 +/- 0.04 (n = 20) and PCO2 increased from 32 +/- 1 to 38 +/- 1 mmHg between deep and tip samples. Bicarbonate delivery decreased from 37 +/- 8 to 7 +/- 1 nmol/min. Titratable acid and ammonium delivery increased from 284 +/- 52 to 347 +/- 62 nmol/min and from 549 +/- 38 to 685 +/- 40 nmol/min, respectively. Calculated net acid excretion increased from 796 +/- 88 to 1,026 +/- 95 nmol/min. Thus during RMA, proton secretion continues along the IMCD, although there is a systemic alkalemia. It appears that factors in addition to systemic acid-base parameters are important in the regulation of proton secretion by the IMCD.

Chronic acid feeding (ACD) stimulates and chronic alkali (AKL) feeding suppresses acid secretion along the inner medullary collecting duct (IMCD) of the rat. The purpose of these experiments was to determine whether these stimuli produce IMCD acidification adaptation. We tested this hypothesis by acutely changing systemic PCO2 in rats chronically fed ACD or ALK. Microcatheterization was used to measure pH and PCO2 and samples were simultaneously obtained for measurement of bicarbonate, titratable acid (TA), and ammonium. In 10 ACD rats (arterial pH, 7.26 +/- 0.01; PCO2, 88 +/- 1 mmHg) acid secretion along the IMCD was 506 +/- 88 nmol/min. In 10 ALK rats with similar arterial gases (pH, 7.16 +/- 0.02; PCO2, 82 +/- 1 mmHg) IMCD acid secretion was only 284 +/- 57 nmol/min, P less than 0.05. In ACD rats made hypocarbic (pH, 7.26 +/- 0.03; PCO2, 24 +/- 1 mmHg), IMCD acid secretion was 163 +/- 55 nmol/min. These data were compared with previously studied rats eating a regular diet. Acute hypocarbia (pH, 7.54 +/- 0.02; PCO2, 20 +/- 1 mmHg) completely suppressed acid secretion, 4 +/- 23 nmol/min, along the IMCD. We conclude that chronic alterations in acid-base status provide an IMCD "set" where comparable stimuli produce significant differences in IMCD acidification. These data provide additional support for the concept of IMCD acidification adaptation.