Dix P. Poppas

A CLINICAL SERIES OF LAPAROSCOPIC NEPHRECTOMY, NEPHROURETERECTOMY AND HEMINEPHROURETERECTOMY IN THE PEDIATRIC POPULATION

PURPOSE Laparoscopic techniques have enabled less invasive surgery in pediatric urology. We report our experience with laparoscopic nephrectomy, nephroureterectomy and heminephroureterectomy in 26 children, and evaluate our series to establish the safety and efficacy of such procedures for benign disease. MATERIALS AND METHODS Laparoscopic procedures were done in 15 girls and 11 boys 4 months to 11 years old (mean age 37) during a 23-month period. Laparascopic surgery consisted of nephrectomy in 14 (1 horseshoe kidney), nephroureterectomy in 6 and laparoscopic heminephroureterectomy in 6 cases. RESULTS Mean overall operative time for the laparoscopic procedures was 165 minutes (range 43 to 355). Blood loss was less than 5 cc in all cases and there were no intraoperative complications in our series. Overall postoperative analgesic administration during hospitalization was 0.20 mg./kg. morphine sulfate and 19 mg./kg. acetaminophen as well as 0.9 mg./kg. codeine in 6 patients who did not receive morphine. Three children were discharged home on the day of surgery, while 17, 3, 1 and 2 were discharged home on postoperative days 1, 2, 4 and 5, respectively. Cosmetic results were excellent in all cases. CONCLUSIONS Nephrectomy, nephroureterectomy and heminephroureterectomy may be performed for benign disease in children using laparoscopy with minimal morbidity, minimal postoperative discomfort, improved cosmesis and a short hospital stay. It may even be done as an outpatient procedure.

Managing varicoceles in children: results with microsurgical varicocelectomy.

Authors from New York present their experience of elective varicocelectomy, using microsurgical techniques, in a large series of children. They found the procedure to be safe and effective, and gave a much lower complication rate than the published rate in open varicocelectomy.

Interstitial fibrosis of unilateral ureteral obstruction is exacerbated in kidneys of mice lacking the gene for inducible nitric oxide synthase

Unilateral ureteral obstruction (UUO) is characterized by decreases in renal function and increases in interstitial fibrosis. Previous studies have indicated that pharmacologic manipulations that increase nitric oxide (NO) are beneficial to the obstructed kidneys. NO is produced from arginine by nitric oxide synthase (NOS), an enzyme that exists in both constitutive and inducible (iNOS) forms. To determine the role of the inducible form of NOS in UUO, we used mice with a targeted deletion of iNOS (iNOS −/− mice) and compared them with wild-type (WT) mice. Kidneys were obstructed for 2 weeks in both WT and iNOS −/− mice, and were then removed and bisected. Half of the kidney was embedded in paraffin and tissue sections were examined for interstitial volume or the presence of macrophages. The remainder was flash-frozen and samples were used to measure tissue collagen (hydroxyproline) or transforming growth factor-β (TGF-β). This study demonstrates that both cortex and medulla of obstructed kidneys of iNOS −/− mice exhibit significantly increased interstitial volume and interstitial macrophages as compared with their WT counterparts. Furthermore tissue collagen was increased to 9.2 ± 1.3 μg/mg tissue in WT obstructed kidneys, whereas in iNOS −/− kidneys, collagen was increased to 13.2 ± 0.8 μg/mg tissue. The profibrotic cytokine TGF-β was also significantly increased in obstructed kidneys of iNOS −/− mice, as compared with WT mice. No differences were noted between the unobstructed kidneys of iNOS −/− mice compared with WT mice in any of the parameters examined. These results demonstrate that targeted deletion of the iNOS results in exacerbation of fibrotic events in the obstructed kidney. These results confirm previous pharmacologic studies, and suggest that NO produced via the inducible NOS normally serves a protective function in UUO.

INTERACTION OF NITRIC OXIDE AND TRANSFORMING GROWTH FACTOR-β1 INDUCED BY ANGIOTENSIN II AND MECHANICAL STRETCH IN RAT RENAL TUBULAR EPITHELIAL CELLS

PURPOSE Changes in intrarenal pressure accompanying unilateral ureteral obstruction can result in tubular mechanical stretch and mediator release from renal tubules. Therefore, we examined the synthesis of nitric oxide and transforming growth factor-beta (TGF-beta), and their interaction in rat renal epithelial cells (NRK-52E) exposed to either angiotensin II or mechanical stretch. MATERIALS AND METHODS NRK-52E were exposed to either angiotensin II or mechanical stretch. Nitrite and TGF-beta in the supernatant were assessed by the Greiss reaction and bioassay, respectively. The level of cell hypertrophy and intracellular TGF-beta protein was determined by flow cytometry. TGF-beta messenger RNA and inducible nitric oxide synthase protein were detected by reverse transcriptase polymerase chain reaction and Western blot, respectively. RESULTS Angiotensin II stimulated TGF-beta1 and nitric oxide. The nitric oxide synthase inhibitor, N-nitro-L-arginine (L-NAME) or angiotensin II type I receptor blocker, losartan, inhibited nitric oxide and TGF-beta1 induced by angiotensin II. Flow cytometry showed that either L-NAME or losartan inhibited angiotensin II induced cell hypertrophy. TGF-beta1 inhibited iNOS protein and nitric oxide, whereas an anti-TGF-beta antibody enhanced iNOS. Mechanical stretch induced TGF-beta, inducible NOS protein and nitric oxide. However, TGF-beta expression was not affected by L-arginine or L-NAME when cells were exposed to mechanical stretch. CONCLUSIONS These results demonstrate that nitric oxide is an intermediate in angiotensin II stimulated TGF-beta1 expression but not in stretch induced TGF-beta expression, and that TGF-beta1 is a negative regulator of nitric oxide in rat renal epithelial cells. The complex interaction of these cytokines may be a target for intervention in the fibrotic and apoptotic processes in the obstructed kidney.

MECHANISM OF HEALING FOLLOWING THE SNODGRASS REPAIR

PURPOSE It has been suggested that healing after tubularized incised plate urethroplasty occurs through re-epithelialization with normal tissue ingrowth or by secondary intent through scarring. We investigated healing in tubularized incised plate urethroplasty. MATERIALS AND METHODS Hypospadias was created in 5 dogs by incising the ventral urethra, allowed to heal for 21 days and subsequently repaired. During hypospadias creation a tattoo was made longitudinally in the midline dorsal urethral plate. The tattoo was bisected during repair, thus creating 2 distinct lines marking the edges of the incision. A neourethra was tubularized and closed in 2 layers. At 21 days the phallus was harvested, inspected and embedded for histology. RESULTS The dorsal urethral plate incision contained 2 distinct lines in all samples representing the area of separation between the native and ingrowing urethras. The distance between these lines was 0.9 +/- 0.1 mm. Proximal urethral lumen diameter (3. 3 +/- 0.1 mm.) was not significantly different from that of the neourethral lumen (3.1 +/- 0.1 mm.). Histologically all repairs had intact squamous epithelium. There was normal appearing subepithelial architecture with scant perivascular lymphocytic infiltrates between the tattoos. In contrast, the area around the sutures showed a desmoplastic (fibroblastic) reaction with an inflammatory, primarily neutrophilic response. CONCLUSIONS Healing of the incision in the dorsal urethral plate during tubularized incised plate urethroplasty occurs by re-epithelialization with normal tissue ingrowth. In contrast, the sutured closure heals with a desmoplastic and inflammatory response.

A novel cell-permeable antioxidant peptide decreases renal tubular apoptosis and damage in unilateral ureteral obstruction.

Unilateral ureteral obstruction (UUO) is characterized by decreases in renal function, increased interstitial fibrosis, tubular apoptosis, and cellular infiltration. It has been suggested that inhibition of tubular apoptosis may protect against renal damage in obstruction. We have recently developed a series of peptides which are concentrated in the inner mitochondrial membrane and prevent cell death. These peptides are also active in vivo, in myocardial infraction, ischemic brain injury, and amyotrophic lateral sclerosis models. We therefore used SS-31, a prototype of these peptides, and assessed its effects on renal damage and oxidative stress in a 14-day obstruction model. SS-31 (1 or 3 mg/kg) or saline was given 1 day before and throughout the 14 days of obstruction. Kidneys were harvested and assessed for apoptosis (terminal transferase-dUTP-nick-end labeling, caspase 3 expression), fibrosis (trichrome staining), macrophage infiltration, fibroblast expression (immunoperoxidase), and oxidative damage (8-OH deoxyguanosine and heme oxygenase-1 expression), cytokines, and signaling pathways (transforming growth factor-beta, CCR-1, p38-MAPK, NF-kappaB). SS-31 significantly attenuated the effects of obstruction on all aspects of renal damage which were examined, with both the 1 and 3 mg/kg doses showing efficacy. We noted increased oxidative stress in obstruction, which was also attenuated by SS-31 treatment. Signaling via NF-kappaB and p38 MAPK pathways were both affected by SS-31 treatment. This study provides a proof of concept that peptides which protect mitochondria in vitro can provide protection from renal damage in a UUO model. The mechanism by which protection is afforded requires further studies both in vitro and in vivo.

Laparoscopic orchiopexy: Clinical experience and description of technique

PURPOSE We reviewed the experience, early followup and technique of laparoscopic treatment of the nonpalpable undescended testis at our institution. MATERIALS AND METHODS Charts of patients who underwent laparoscopic treatment of an intra-abdominal testis from September 1992 to October 1994 were reviewed. RESULTS A total of 13 laparoscopic orchiopexies was performed on 11 children with nonpalpable undescended testes. In 10 cases sufficient length was gained on the spermatic vessels using laparoscopic dissection to perform tension-free orchiopexy without the need for division of the spermatic vessels. CONCLUSIONS When localization of an intra-abdominal testis is confirmed, orchiopexy can be performed safely with minimal morbidity using a laparoscopic approach. Length of hospital stay and postoperative morbidity may be improved in comparison to traditional techniques.

Patch graft urethroplasty using dye enhanced laser tissue welding with a human protein solder: a preclinical canine model.

We investigated the use of the KTP-532 laser to perform a patch graft urethroplasty in 24 adult male dogs using the inner preputial skin as the donor site. In group 1 (12 dogs) repairs were completed with conventional microsuturing techniques, while in group 2 (12 dogs) they were completed using the KTP-532 laser. In the laser welding group the addition of a protein solder (40% human albumin) doped with fluorescein was used. Assessment parameters included a preoperative and postoperative retrograde urethrogram, measurement of intraluminal bursting pressure in the first 6 animals in each group, operative time and histology. Operative time was 42% faster and acute intraluminal bursting pressures were significantly higher in the laser-solder group. No fistulas occurred in the laser-solder group compared to a 50% fistula rate in the suture group. Significant radiographic abnormalities were seen in the urethras of the suture repair group.

LASER TISSUE WELDING

Laser tissue welding is a technologic innovation that is beginning to move from the theoretical laboratory environment to the reality of clinical application. This article reviews the concepts, potential advantages, and techniques involved in laser tissue welding as they apply to urology.

Effects of Transforming Growth Factor-β1 on Human Vocal Fold Fibroblasts

Objectives: We studied the effect of transforming growth factor (TGF)–β on immortalized human vocal fold fibroblasts. Methods: Normal human vocal fold fibroblasts were subjected to sequential lentiviral transduction with genes for human telomerase (hTERT) and SV40 large T antigen in order to produce an “immortalized” cell line of normal phenotype. After confirmation of vocal fold fibroblast transfection, these cells, referred to as HVOX, were treated with various concentrations of exogenous TGF-β1 and assayed for collagen secretion, migration, and proliferation. In addition, components of the TGF-β signaling pathway were examined in this cell line. Results: TGF-β stimulated collagen secretion and migration without altering proliferation of HVOX. HVOX constitutively expressed type I and II TGF-β receptors, as well as messenger RNA for the Smad signaling proteins and for all TGF-β isoforms. Exogenous TGF-β1 induced temporally dependent alterations in Smad2 and Smad3 gene expression. TGF-β increased Smad7 expression at both 4 and 24 hours. Prolonged exposure to TGF-β decreased TGF-β1 gene expression. Conclusions: Insight into the underlying pathophysiology of vocal fold fibrosis is likely to yield improved therapeutic strategies to mitigate vocal fold scarring. Our data suggest that TGF-β signaling may be both paracrine and autocrine in this vocal fold fibroblast cell line, and we therefore propose that TGF-β may be a reasonable target for therapies to prevent and/or treat vocal fold fibrosis, given its putative role in both acute and chronic vocal fold injury, as well as its effects on vocal fold fibroblasts.