Development of male and female models of long urethral strictures in swine.

Background: Preclinical animal models which mimic the dimensions of long urethral strictures (>2 cm in length) encountered in the clinic are necessary to evaluate prospective graft designs for urethroplasty. The purpose of this study was to develop both male and female porcine models of long urethral strictures (∼4 cm in length) and characterize histological and functional outcomes of iatrogenic stricture formation between genders. Methods: Focal, partial thickness urethral injuries were created over 5-6 cm long segments in male and female swine (N = 4 per gender) via electrocoagulation and the degree of stricture formation was monitored for up to 6 weeks by urethroscopy and retrograde urethrography. Animals were sacrificed following stricture confirmation and histological, immunohistochemical, and histomorphometric analyses were performed on strictured and uninjured control urethral segments to profile wound healing responses. Results: Urethral stricture formation was detected in all female swine by 2 weeks and 100 % of male swine at 3.2 ± 1.8 weeks, post-operatively. The mean length of urethral strictures in both male and female swine was ∼4 cm. Substantial variations in the degree of stricture severity between sexes were observed with males exhibiting significant urethral stenosis and loss of α-smooth muscle actin+ smooth muscle bundles in comparison to controls, while females primarily displayed defects in pan-cytokeratin+ epithelia as well as functional urethral obstruction. Conclusions: Electrocoagulation injury is sufficient to produce long urethral strictures in male and female swine and the degree of stricture severity and nature of urethral obstruction was observed to be dependent on gender. Animal Protocol: AUP-19-150. Key message: Novel male and female models of long urethral strictures in swine were created to characterize histological and functional outcomes of iatrogenic stricture formation between genders.

Evaluation of silk fibroin-based urinary conduits in a porcine model of urinary diversion.

Background: The primary strategy for urinary diversion in radical cystectomy patients involves incorporation of autologous gastrointestinal conduits into the urinary tract which leads to deleterious consequences including chronic infections and metabolic abnormalities. This report investigates the efficacy of an acellular, tubular bi-layer silk fibroin (BLSF) graft to function as an alternative urinary conduit in a porcine model of urinary diversion. Materials and methods: Unilateral urinary diversion with stented BLSF conduits was executed in five adult female, Yucatan mini-swine over a 3 month period. Longitudinal imaging analyses including ultrasonography, retrograde ureteropyelography and video-endoscopy were carried out monthly. Histological, immunohistochemical (IHC), and histomorphometric assessments were performed on neoconduits at harvest. Results: All animals survived until scheduled euthanasia and displayed moderate hydronephrosis (Grades 1-3) in reconstructed collecting systems over the course of the study period. Stented BLSF constructs supported formation of vascularized, retroperitoneal tubes capable of facilitating external urinary drainage. By 3 months post-operative, neoconduits contained α-smooth muscle actin+ and SM22α+ smooth muscle as well as uroplakin 3A+ and pan-cytokeratin + urothelium. However, the degree of tissue regeneration in neotissues was significantly lower in comparison to ureteral controls as determined by histomorphometry. In addition, neoconduit stenting was necessary to prevent stomal occlusion. Conclusion: BLSF biomaterials represent emerging platforms for urinary conduit construction and may offer a functional replacement for conventional urinary diversion techniques following further optimization of mechanical properties and regenerative responses.

DNA Methylation Dynamics During Esophageal Epithelial Regeneration Following Repair with Acellular Silk Fibroin Grafts in Rat.

Esophageal pathologies such as atresia and benign strictures often require surgical reconstruction with autologous tissues to restore organ continuity. Complications such as donor site morbidity and limited tissue availability have spurred the development of acellular grafts for esophageal tissue replacement. Acellular biomaterials for esophageal repair rely on the activation of intrinsic regenerative mechanisms to mediate de novo tissue formation at implantation sites. Previous research has identified signaling cascades involved in neoepithelial formation in a rat model of onlay esophagoplasty with acellular silk fibroin grafts, including phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) signaling. However, it is currently unknown how these mechanisms are governed by DNA methylation (DNAme) during esophageal wound healing processes. Reduced-representation bisulfite sequencing is performed to characterize temporal DNAme dynamics in host and regenerated tissues up to 1 week postimplantation. Overall, global hypermethylation is observed at postreconstruction timepoints and an inverse correlation between promoter DNAme and the expression levels of differentially expressed proteins during regeneration. Site-specific hypomethylation targets genes associated with immune activation, while hypermethylation occurs within gene bodies encoding PI3K-Akt signaling components during the tissue remodeling period. The data provide insight into the epigenetic mechanisms during esophageal regeneration following surgical repair with acellular grafts.

Porcine Bladder Replacement with a Bilayer Silk Fibroin Enhanced Prosthetic Reservoir: A Feasibility Study.

Introduction: The creation of synthetic reservoirs for bladder replacement has been limited by challenges of interfacing synthetic materials and native tissue. We sought to overcome this challenge by utilizing a novel bilayer silk fibroin scaffold (BLSF) as an intermediary toward the development of an acellular prosthetic reservoir. Methods: Under institutionally approved protocols, 3D-printed reservoirs were implanted in six juvenile female pigs after cystectomy. BLSF was attached to the in situ prosthetic reservoir serving as an intermediary to native ureteral and urethral tissue anastomoses. Our first protocol allowed four pigs to be survived up to 7 days, and the second protocol allowed two pigs to be survived for up to 1 year. At the first sign of functional decline or the end of the study period, the animals were euthanized, and kidneys, ureters, prosthetic bladder, and urethra were harvested en bloc for histopathology analysis. Results: The first two pigs had anastomotic urine leaks because of design flaws resulting in early termination. The third pig had acute renal failure resulting in early termination. The artificial bladder design was modified in subsequent iterations. The fourth pig survived for 7 days and, upon autopsy, had intact urethral and ureteral anastomoses. The fifth and sixth pigs survived for 11 and 12 weeks, respectively, before they were sacrificed because of failure to thrive. One animal developed an enteric fistula. The other animal had an intact anastomosis, and the BLFS was identified at the ureteral and urethral anastomoses on histopathologic analysis. Conclusions: Replacing the porcine bladder with a prosthetic bladder was achieved for up to 3 months, the second longest survival period for a nonbiologic bladder alternative. BLSF was used for the first time to create an interface between synthetic material and biologic tissue by allowing ingrowth of urothelium onto the acellular alloplastic bladder.

Molecular mechanisms of esophageal epithelial regeneration following repair of surgical defects with acellular silk fibroin grafts.

Constructive remodeling of focal esophageal defects with biodegradable acellular grafts relies on the ability of host progenitor cell populations to repopulate implant regions and facilitate growth of de novo functional tissue. Intrinsic molecular mechanisms governing esophageal repair processes following biomaterial-based, surgical reconstruction is largely unknown. In the present study, we utilized mass spectrometry-based quantitative proteomics and in silico pathway evaluations to identify signaling cascades which were significantly activated during neoepithelial formation in a Sprague Dawley rat model of onlay esophagoplasty with acellular silk fibroin scaffolds. Pharmacologic inhibitor and rescue experiments revealed that epithelialization of neotissues is significantly dependent in part on pro-survival stimuli capable of suppressing caspase activity in epithelial progenitors via activation of hepatocyte growth factor receptor (c-MET), tropomyosin receptor kinase A (TrkA), phosphoinositide 3-kinase (PI3K), and protein kinase B (Akt) signaling mechanisms. These data highlight the molecular machinery involved in esophageal epithelial regeneration following surgical repair with acellular implants.

Evaluation of Acellular Bilayer Silk Fibroin Grafts for Onlay Tracheoplasty in a Rat Defect Model.

OBJECTIVE: To assess the efficacy of acellular bilayer silk fibroin (BLSF) grafts to repair full-thickness tracheal defects and to compare the performance with conventional porcine small intestinal submucosa (SIS) implants. STUDY DESIGN: A prospective controlled animal trial in a rat model of onlay tracheoplasty. SETTING: Pediatric medical center. SUBJECTS AND METHODS: Tracheal reconstruction of adult Sprague-Dawley rats was performed with BLSF (n = 38) or SIS (n = 32) matrices for up to 3 months of implantation. Functional evaluations of repaired conduits as well as histologic, immunohistochemical, and histomorphometric analyses of neotissues were assessed. RESULTS: Prior to scheduled euthanasia, survival rates of rats receiving BLSF or SIS grafts were ≥94%, with no clinical signs of airway obstruction observed over the course of the study. Micro-computed tomography analysis revealed that the mean percentage of stenosis was <20% in both implant groups. BLSF and SIS grafts supported formation of pseudostratified ciliated columnar epithelium by 1 week postoperatively; however, each matrix failed to promote de novo chondrogenesis by 3 months following repair. CONCLUSIONS: BLSF scaffolds can be used for reconstruction of rat tracheal patch defects with functional outcomes comparable to those of SIS matrices.

Does Voiding Cystourethrogram Exclude Posterior Urethral Valves in Late Presenting Cases?

INTRODUCTION: Delayed presentation of posterior urethral valves (PUVs) is a rare condition. Presentation and diagnosis of the patients with late PUVs are challenging. Voiding cystourethrogram (VCUG) is mainly practiced. In this study, we aimed to evaluate the children with late-presented PUVs, and the reliability of VCUG in this group. MATERIALS AND METHODS: Between January 2003 and December 2017 records of patients who were diagnosed with late-presented PUVs were analyzed. Delayed presentation of PUV was defined as patients who were diagnosed and treated after infancy. Cases were examined in terms of age at diagnosis, presenting symptoms, urinalysis, urinary ultrasound, urodynamic studies, VCUG, and dimercaptosuccinic acid scintigraphy findings. Postoperative follow-up conditions were also assessed. RESULTS: Seventeen boys were diagnosed with late-presented PUVs (mean age was 7.35 years). The most common symptoms at presentation were frequency (58.8%), day and nighttime incontinence (47%), and febrile urinary infection (41%). PUV was noted by VCUG in 10 patients alone. The classical sign of dilated posterior urethra was detected in 9 patients. The 10th patient had posterior urethral irregularity. Urethra could not be evaluated due to unsuccessful voiding in one patient. Six patients had normally appearing urethra on VCUG. Reflux was detected in nine (52.9%) patients. CONCLUSION: Late-presented PUVs may be missed on VCUG. Whether a PUV might be present is crucial in boys with a history of recurrent urinary infection, persistent reflux, and repetitive daytime incontinence. Based on our results, we conclude that cystoscopic examination should be preferred for those cases to diagnose PUVs regardless of VCUG results.

Augmentation Cystoplasty of Diseased Porcine Bladders with Bi-Layer Silk Fibroin Grafts.

IMPACT STATEMENT: The search for an ideal "off-the-shelf" biomaterial for augmentation cystoplasty remains elusive and current scaffold configurations are hampered by mechanical and biocompatibility restrictions. In addition, preclinical evaluations of potential scaffold designs for bladder repair are limited by the lack of tractable large animal models of obstructive bladder disease that can mimic clinical pathology. The results of this study describe a novel, minimally invasive, porcine model of partial bladder outlet obstruction that simulates clinically relevant phenotypes. Utilizing this model, we demonstrate that acellular, bi-layer silk fibroin grafts can support the formation of vascularized, innervated bladder tissues with functional properties.

Spontaneous evisceration of umbilical hernia in a patient with congenital nephrotic syndrome.

Congenital nephrotic syndrome is a term used to describe a condition in babies who develop severe proteinuria and hypoalbuminaemia within their first three months of life. They generally have oedema and ascites from birth which, because of increased intra-abdominal pressure, can result in an umbilical hernia. The report presents a five-month old infant with congenital nephrotic syndrome who had spontaneous umbilical hernia rupture with evisceration. The approach to umbilical hernias is usually conservative, but in selected cases elective surgery may be indicated.

Isolated penile torsion in newborns.

INTRODUCTION: We reported on the incidence of isolated penile torsion among our healthy children and our approach to this anomaly. METHODS: Between 2011 and 2014, newborn babies with penile torsion were classified according to the angle of torsion. Surgical correction (penile degloving and reattachment for moderate cases and dorsal dartos flap technique in case of resistance) after 6 months was advised to the babies with rotations more than 45°. RESULTS: Among 1000 newborn babies, 200 isolated penile torsions were found, and among these, 43 had torsions more than 45°, and 4 of these had angles greater than 90°. The mean angle of the rotations was found 30.45° (median: 20°). In total, 8 children with 60° torsions were previously circumcised. Surgery was performed on 19 patients, with a mean patient age of 12 ± 2 months. Of these 19, 13 babies were corrected with degloving and reattachment. This technique was not enough on the remaining 6 patients; therefore, derotational dorsal dartos flap was added to correct the torsion. After a mean of 15.6 ± 9.8 months, residual penile rotation, less than 15°, was found only in 2 children. CONCLUSION: The incidence of isolated penile torsion is 20% in newborns. However, rotation more than 45° angles are seen in 4.3% of male babies. Correction is not necessary in mild degrees, and penile degloving with reattachment is enough in most cases. If the initial correction is insufficient, dorsal dartos flap rotation is easy and effective. Prior circumcision neither disturbs the operative procedure nor affects the outcomes.

Remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy: comparison of adjuvant propofol and ketamine.

OBJECTIVE: Laryngoscopy and stimuli inside the trachea cause an intense sympatho-adrenal response. Remifentanil seems to be the optimal opioid for rigid bronchoscopy due to its potent and short-acting properties. The purpose of this study was to compare bolus propofol and ketamine as an adjuvant to remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy. MATERIALS AND METHODS: Forty children under 12 years of age who had been scheduled for a rigid bronchoscopy were included in this study. After midazolam premedication, a 1 µg/kg/min remifentanil infusion was started, and patients were randomly allocated to receive either propofol (Group P) or ketamine (Group K) as well as mivacurium for muscle relaxation. Anesthesia was maintained with a 1 µg/kg/min remifentanil infusion and bolus doses of propofol or ketamine. After the rigid bronchoscopy, 0.05 µg/kg/min of remifentanil was maintained until extubation. Hemodynamic parameters, emergence characteristics, and adverse events were evaluated. RESULTS: The demographic variables were comparable between the two groups. The decrease in mean arterial pressure from baseline values to the lowest values during rigid bronchoscopy was greater in Group P (p = 0.049), while the reduction in the other parameters and the incidence of adverse events were comparable between the two groups. The need for assisted or controlled mask ventilation after extubation was higher in Group K. CONCLUSION: Remifentanil-based total intravenous anesthesia with propofol or ketamine as an adjuvant drug along with controlled ventilation is a viable technique for pediatric rigid bronchoscopy. Ketamine does not provide a definite advantage over propofol with respect to hemodynamic stability during rigid bronchoscopy, while propofol seems more suitable during the recovery period.

Remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy: comparison of adjuvant propofol and ketamine

OBJECTIVE: Laryngoscopy and stimuli inside the trachea cause an intense sympatho-adrenal response. Remifentanil seems to be the optimal opioid for rigid bronchoscopy due to its potent and short-acting properties. The purpose of this study was to compare bolus propofol and ketamine as an adjuvant to remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy. MATERIALS AND METHODS: Forty children under 12 years of age who had been scheduled for a rigid bronchoscopy were included in this study. After midazolam premedication, a 1 µg/kg/min remifentanil infusion was started, and patients were randomly allocated to receive either propofol (Group P) or ketamine (Group K) as well as mivacurium for muscle relaxation. Anesthesia was maintained with a 1 µg/kg/min remifentanil infusion and bolus doses of propofol or ketamine. After the rigid bronchoscopy, 0.05 µg/kg/min of remifentanil was maintained until extubation. Hemodynamic parameters, emergence characteristics, and adverse events were evaluated. RESULTS: The demographic variables were comparable between the two groups. The decrease in mean arterial pressure from baseline values to the lowest values during rigid bronchoscopy was greater in Group P (p = 0.049), while the reduction in the other parameters and the incidence of adverse events were comparable between the two groups. The need for assisted or controlled mask ventilation after extubation was higher in Group K. CONCLUSION: Remifentanil-based total intravenous anesthesia with propofol or ketamine as an adjuvant drug along with controlled ventilation is a viable technique for pediatric rigid bronchoscopy. Ketamine does not provide a definite advantage over propofol with respect to hemodynamic stability during rigid bronchoscopy, while propofol seems more suitable during the recovery period. .

Carbon dioxide insufflation causes upper urinary tract injury in the early period of an experimental vesicoureteral reflux model.

PURPOSE: Ureteral reimplantation via pneumovesicum is a new aspect of vesicoureteral reflux management. We aimed to determine the effects of carbon dioxide (CO2) insufflation on the upper urinary tract in an experimental model. MATERIALS AND METHODS: Thirty New Zealand rabbits were allocated into five groups of six rabbits each. Right ureters were cannulated for CO2 insufflation in four groups. The pressures and durations of CO2 insufflation in the respective groups were as follows: Group A (10 mm Hg, 2 h); B (12 mm Hg, 2 h); C (10 mm Hg, 4 h); and D (12 mm Hg, 4 h) and control (E). Blood gas analysis, urea and creatinine levels were measured from renal veins and aorta. Histopathological evaluation of the renal parenchyma and ureters was scored. RESULTS: Significant histopathological changes were detected in the ipsilateral ureter and renal parenchyma exposed to CO2 insufflation, predominantly observed in groups insufflated for longer durations, p < 0.05. Blood gases drawn separately from renal veins were significantly more acidotic, and serum urea and creatinine levels were increased in all the groups, p < 0.05. CONCLUSIONS: CO2 causes significant histopathological and biochemical changes in the early period. Long-term results are required to determine whether permanent renal injury occurs.

Laparoscopic correction of right transverse colostomy prolapse.

Colostomy prolapse is a frequently seen complication of transverse colostomy. In one child with recurrent stoma prolapse, we performed a loop-to-loop fixation and peritoneal tethering laparoscopically. No prolapse had recurred at follow-up. Laparoscopic repair of transverse colostomy prolapse seems to be a less invasive method than other techniques.

Melatonin ameliorates necrotizing enterocolitis in a neonatal rat model.

INTRODUCTION: We designed the present study to evaluate the efficacy of melatonin (M) on the severity of necrotizing enterocolitis (NEC) in a neonatal rat model. MATERIALS AND METHODS: Immediately after birth, pups were weighed and randomized into 3 groups: NEC, NEC + M, and control. Necrotizing enterocolitis was induced by enteral formula feeding and exposure to hypoxia after cold stress at 4°C and oxygen. The NEC + M group received 10 mg/kg M daily for 3 days after the first day of the NEC procedure. The pups were killed on the fourth day, and their intestinal tissues were harvested for biochemical and histopathologic analysis. Blood samples were also obtained from the pups. RESULTS: The mortality rate and weight loss were highest in the NEC group. Malondialdehyde and protein carbonyl content were significantly increased, whereas superoxide dismutase and glutathione peroxidase were decreased in the NEC-treated pups. Melatonin prevented these changes, with these values being similar to control levels in the NEC + M group. Nitrate plus nitrite levels and serum tumor necrosis factor α and interleukin-1ß were increased in the NEC group, and histopathologic injury score in the NEC group was significantly higher than that in the NEC + M group. CONCLUSION: Melatonin significantly reduced the severity of NEC in our study.

Pelvic floor tonicity affects urodynamic measurements in children with myelomeningocele.

OBJECTIVE: In a cystometry procedure in a child with myelomeningocele (MMC), a pressure increase in the abdominal pressure (P (abd)) tracing was detected during filling. This pressure alteration was not related to other known events (straining, talking, rectal contractions). This study was conducted to investigate this phenomenon. MATERIAL AND METHODS: Forty-three children with MMC were enrolled in the study. A slow and gradual pressure increase associated with the bladder filling was sought in the P (abd) tracings. End filling and initial P (abd) gradient more than 3 cm H(2)O were considered as increased P (abd). If the defined pressure event occurs, the bladder was evacuated for verifying the filling-pressure relation. Age, gender, study position, pelvic floor tonicity and cystometric capacity were correlated with the pressure alteration. RESULTS: P (abd) increase was noted in 18 (41.8%) children. The mean P (abd) gradient between end and initial filling was 4.78 ± 1.63 cm H(2)O in these children. No statistically significant difference was noted for age, gender and study position. Statistically significant differences were noted with decreased pelvic floor tonicity and high values of cystometric capacity (p = 0.003 and p < 0.001, respectively). CONCLUSIONS: The pressure increase is thought to be a consequence of a posterior positional change in the bladder during filling die to decreased pelvic floor support in MMC. This pressure alteration was more obvious with increased bladder capacity. Urodynamic studies of children with MMC should be carefully evaluated for the presence of this phenomenon to prevent low measurement of the detrusor pressure, compliance and detrusor leak point pressure values.

Testicular torsion in the left inguinal canal in a patient with inguinal hernia: a difficult case to diagnose.

A 8 month old boy suffering from inconsolable cry and tenderness presented to our hospital. Ten hours had passed from the onset of his symptoms. Physical examination showed a tender mass on the left groin. Patient was evaluated with Doppler ultrasound and Technetium-99m pertechnetate testicular scintigraphy Differential diagnosis of torsion and inflammatory disease could not be made by adjunctive tests. The patient underwent surgery based on clinical findings and necrotic inguinal left gonad was shown. In this study, we discussed the scintigraphic pattern in a patient with torsion in undescended inguinal testicle Conflict of interest:None declared.

Pyeloureterostomy in the management of the lower pole pelvi-ureteric junction obstruction in incomplete duplicated systems.

OBJECTIVES: To report our experience with the pyeloureterostomy (PU) for the treatment of the lower pole PUJO in incomplete duplex systems. The combination of the duplicated collecting system and pelviureteric junction obstruction (PUJO) is a rare association and infrequently reported. Surgical treatment can be challenging in such cases. METHODS: We retrospectively reviewed the medical data of the patients who had surgery from 2001 to 2009, with a diagnosis of PUJO of the lower pole moiety in incomplete duplex system. Demographic, diagnostic, and procedural data were recorded. RESULTS: Seven patients were identified with the lower pole PUJO associated with incomplete duplex systems. Their median age was 49 months (range 2-108 months). Prenatal hydronephrosis was detected in 3 patients, and 4 had a febrile urinary tract infection. PU was performed in 6 patients because of short ureteral length between the ureteropelvic junction and junction of lower and upper pole ureters. One patient was treated with the dismembered pyeloplasty because of sufficient ureteral length of the lower pole. No complications were detected during 14 months of follow-up. CONCLUSIONS: The management of the lower pole PUJO in incomplete duplex systems should be individualized for every patient. PU is a good surgical option in the management of the lower pole PUJO associated with incomplete ureteral duplication.