Linda A. Baker

Reprogramming of human fibroblasts toward a cardiac fate

Reprogramming of mouse fibroblasts toward a myocardial cell fate by forced expression of cardiac transcription factors or microRNAs has recently been demonstrated. The potential clinical applicability of these findings is based on the minimal regenerative potential of the adult human heart and the limited availability of human heart tissue. An initial but mandatory step toward clinical application of this approach is to establish conditions for conversion of adult human fibroblasts to a cardiac phenotype. Toward this goal, we sought to determine the optimal combination of factors necessary and sufficient for direct myocardial reprogramming of human fibroblasts. Here we show that four human cardiac transcription factors, including GATA binding protein 4, Hand2, T-box5, and myocardin, and two microRNAs, miR-1 and miR-133, activated cardiac marker expression in neonatal and adult human fibroblasts. After maintenance in culture for 4–11 wk, human fibroblasts reprogrammed with these proteins and microRNAs displayed sarcomere-like structures and calcium transients, and a small subset of such cells exhibited spontaneous contractility. These phenotypic changes were accompanied by expression of a broad range of cardiac genes and suppression of nonmyocyte genes. These findings indicate that human fibroblasts can be reprogrammed to cardiac-like myocytes by forced expression of cardiac transcription factors with muscle-specific microRNAs and represent a step toward possible therapeutic application of this reprogramming approach.

Trocar-less Instrumentation for Laparoscopy: Magnetic Positioning of Intra-abdominal Camera and Retractor

Objective:To develop a novel laparoscopic system of moveable instruments that are positioned intra-abdominally and “locked” into place by external permanent magnets placed on the abdomen. Summary Background Data:In conventional laparoscopy, multiple trocars are required because of the limited degrees of freedom of conventional instrumentation, and the limited working envelope (an inverted cone) created by the fulcrum motion around each port. While robotic systems can improve the number of degrees of freedom, they are restricted by even smaller working envelopes. Methods:A collaborative research group from the Department of Urology and the Automation & Robotics Research Institute of the University of Texas, Arlington built a prototype system of magnetically anchored instruments for trocar-less laparoscopy. The only design mandate was that the developed technology be able to pass into the abdomen through one existing 12-mm diameter trocar. Results:A transabdominal “magnetic anchoring and guidance system” (MAGS) platform was developed to incorporate instruments, retractors, and a controllable intra-abdominal camera. In vitro, the platform was able to anchor 375 and 147 g across porcine tissue 1.8 and 2.5 cm thick, respectively. The permanent magnet platforms were sufficiently strong to retract the porcine liver and securely anchor the camera. Its versatility was demonstrated by moving the camera to virtually any location in the peritoneum with no working envelope restrictions and the subsequent completion of porcine laparoscopic procedures with 2 trocars only. Conclusions:Trocar-less laparoscopy using magnetically anchored instruments is feasible and may expand intracorporeal instrument manipulation substantially beyond current-day capability. The ability to reduce the number of trocars necessary for laparoscopic surgery has the potential to revolutionize surgical practice.

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.

An Analysis of Clinical Outcomes Using Color Doppler Testicular Ultrasound for Testicular Torsion

Objectives. To delineate the clinical outcomes of color Doppler ultrasound (US) in the equivocal torsion patient. Methods. From 1992 to 1997, 130 patients (<23 years old) from 2 institutions underwent US imaging using a 7.5-mHz linear transducer to evaluate an acute scrotum equivocal, or of low suspicion, for torsion. The US reports and hospital charts of these patients were retrospectively reviewed. Results. After clinical and radiologic evaluation, torsion was excluded in 110 patients without surgical exploration. In 3 patients, intermittent testicular torsion was diagnosed and in 17 patients, emergent exploration was performed for US diagnosis of testicular torsion. Twenty-five patients (22.7%) were subsequently lost to follow-up. Follow-up of 85 patients with US negative for torsion (mean length of follow-up = 466.9 days) revealed no testicular atrophy in 83. Two patients underwent delayed orchiectomy/contralateral orchiopexy for missed testicular torsion. Of 17 patients with US positive for torsion, 9 underwent orchiectomy for a necrotic torsed testis, 7 viable torsed testes were found, and 1 torsed appendix testis was found. Therefore, color Doppler US for the equivocal acute scrotum yielded a 1% false-positive rate, sensitivity of 88.9%, and specificity of 98.8%. Conclusion. When faced with ruling out testicular torsion, it is necessary to integrate the multiple pieces of patient data, knowing that each piece of data may have inaccuracies. With this in mind, this analysis of outcomes verifies that color Doppler US is an excellent adjunctive study in the clinically real situation in which the clinical evaluation is equivocal or low suspicion.

Hospitalizations for Pediatric Stone Disease in United States, 2002–2007

PURPOSE Although more common in adults, urolithiasis recently has been occurring with increasing frequency in children. Single institution reviews from 1950 to 1990 revealed that urolithiasis accounts for 1 in 7,600 to 1 in 1,000 pediatric hospitalizations. Stone prevalence and risk factors for hospitalization are less defined in children in North America compared to adults. To identify pediatric hospital admissions due to a diagnosis of urinary stones, we examined Pediatric Health Information System data from 41 freestanding pediatric hospitals. MATERIALS AND METHODS We retrospectively studied patients younger than 18 years hospitalized between 2002 and 2007. The Pediatric Health Information System database, a validated collection of pediatric hospital data, was searched for inpatients with a primary ICD-9 diagnosis of urolithiasis. RESULTS Among more than 2.7 million pediatric inpatients from 2002 to 2007, 3,989 hospitalizations were for 3,815 patients with urolithiasis. In contrast to adults, girls had a 1.5-fold greater likelihood of being hospitalized for stones. More than half of the children (53.1%) were younger than 13 years (mean 12.3, SD 4.23). Most patients (88%) were white. Stone hospitalizations were more common in the North Central region compared to the South. Hospitalizations for stones increased slightly in August and September. Nephrectomy was performed in nearly 1% of stone hospitalizations (29 of 3,170). CONCLUSIONS Children with stones now account for 1 in 685 pediatric hospitalizations in the United States. Surprisingly more than half of the patients are younger than 13 years at hospitalization. Similar to findings in adults, white race and occurrence in late summer months increase the risk of stone hospitalization. However, male gender and geographic location in the Southeast are not risk factors, demonstrating the unique aspects of pediatric stone hospitalization.

Clinical use of the holmium: YAG laser in laparoscopic partial nephrectomy.

PURPOSE To report on the technique and utility of the holmium: YAG laser in performing laparoscopic partial nephrectomy (LPN). PATIENTS AND METHODS Three patients with indications for LPN (complex cyst, nonfunctioning lower pole, renal mass) underwent parenchymal-sparing procedures with the Ho:YAG laser. The kidney was identified using a transperitoneal laparoscopic technique. Gerotas fascia was opened, and the renal mass/nonfunctioning lower pole was resected using the laser. Settings of 0.2 J/pulse at 60 pulses/sec and 0.8 J/pulse at 40 pulses/sec were used. RESULTS All three procedures were performed successfully with minimal blood loss and without the need for hilar occlusion. Although the laser alone was hemostatic, fibrin glue was applied in two cases and oxidized cellulose in one case to reinforce the tissue against delayed bleeding. There were no perioperative complications, and all patients left the hospital within 3 days. CONCLUSIONS At high power settings, the Ho:YAG laser is an effective tool for LPN. It results in good hemostasis without the need for hilar occlusion. This technique promises to facilitate the laparoscopic management of renal tumors and nonfunctioning moieties of duplicated systems.

The Insulin-3 Gene: Lack of a Genetic Basis for Human Cryptorchidism

PURPOSE The etiology of cryptorchidism appears to be multifactorial and related to hormonal and mechanical factors. Recently, the insulin-3 gene (INSL3) was noted to have a role in mouse gubernacular development and testicular descent. Knockout male mice for the INSL3 gene show isolated bilateral cryptorchidism. This phenotype suggests that INSL3 may have a role in the development of human cryptorchidism. Using single strand conformational polymorphism analysis we detected mutations of the INSL3 gene in boys with cryptorchidism. MATERIALS AND METHODS Genomic DNA from 118 boys with cryptorchidism and 48 normal controls were obtained from 3 institutions. Using polymerase chain reaction with INSL3 sequence specific primers DNA fragments were analyzed using single strand conformational polymorphism reactions. Samples with band shifts were re-amplified and sequenced to detect mutations. RESULTS A single base substitution (G greater than A) causing an amino acid change (missense mutation) was identified in 27 of 118 cryptorchid (23%) samples and 12 of 48 normal (25%) samples. Two other base substitutions did not produce alterations in the amino acid sequence (silent mutations). CONCLUSIONS Although a common polymorphism was detected in the INSL3 gene, no specific mutations were detected in a large population of individuals with cryptorchidism. Therefore, mutations in the coding region of the INSL3 gene are not a common cause of human cryptorchidism.

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.

The staged approach to bladder exstrophy closure and the role of osteotomies

Abstract Since the 1970s, the staged reconstruction of bladder exstrophy has yielded consistent surgical success. The Johns Hopkins Hospital approach begins with early pelvic ring approximation with abdominal wall, bladder, and posterior urethral closure. Within the first 72 hours of life, the malleable pelvis can sometimes be approximated without osteotomies. Beyond this age, the authors prefer a combined vertical iliac and horizontal innominate osteotomy. Second, we typically perform the epispadias closure at 1 year of age. A modified Cantwell-Ransley technique is performed, usually yielding an increase in bladder capacity and very satisfactory results. In the last phase, the modified Young-Dees-Leadbetter continence procedure along with transtrigonal/cephalotrigonal ureteroneocystostomies are performed when the urethra is catheterizable, the bladder capacity is 60cc or greater, and the child will participate in a postoperative voiding program (typically 4–5 years of age). This applied approach usually results in a continent, voiding patient with pleasing external genitalia and preserved renal function.

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.