Biomedical subjects

A B Retik

Publications and source records attributed to A B Retik.

At least 55 records · Page 3Linked to original sources

PubMed1995

Fetal suprarenal masses: sonographic appearance and differential diagnosis.

We present eight cases of suprarenal masses detected sonographically in fetuses of 20-41 weeks. The appearances of the masses included hyperechoic (n = 2, both pulmonary sequestrations), solid isoechoic (n = 1, a neuroblastoma), purely cystic (n = 3, two neuroblastomas, one enteric cyst) and mixed or complex (n = 2, one neuroblastoma and one renal cyst). Three of the fetuses with neuroblastoma had normal scans in the second trimester, and in all four the neuroblastomas were detected after 36 weeks. This study demonstrates the differential diagnosis of suprarenal masses in fetuses. Neuroblastomas can have a solid, purely cystic or complex sonographic appearance. Although not all suprarenal masses are neuroblastomas, the newborn with a prenatally detected suprarenal mass should be evaluated for the possibility of a neuroblastoma, since early diagnosis of this malignancy can be curative.

Adrenal Gland Neoplasms↗

PubMed1995

Comparative urodynamics of appendiceal and ureteral Mitrofanoff conduits in children.

We report the cystometric and conduit pressure profilometric findings of 20 children for whom the Mitrofanoff principle was applied to the construction of 21 continent catheterizable urinary conduits. Mitrofanoff conduits were fashioned from ureter in 10 cases, appendix in 8, ileum in 1, stomach in 1 and a combination appendix and ureter in 1. Conduit pressure profiles showed that functional profile length correlated strongly with the static profile maximal Mitrofanoff closure pressure (p = 0.04) and dynamic profile maximal Mitrofanoff closure pressure (p = 0.02). There was a statistically significant difference between clinical continence rates for children above and below the functional profile length threshold of 2.0 cm. (p = 0.05). The zone of continence corresponded to the region of the conduit intramural tunnel. Only 2 of 21 conduits were incontinent but both were constructed with ureters implanted into bowel reservoirs. Compared to appendiceal conduits, ureteral conduits had a lower functional profile length (p < 0.01) and static profile maximal Mitrofanoff closure pressure (p < 0.01), indicating a possible advantage to the use of the appendix.

Adolescent↗

PubMed1995

The long-term urological response of neonates with myelodysplasia treated proactively with intermittent catheterization and anticholinergic therapy.

PURPOSE: Urinary tract management in children with myelodysplasia is controversial. Some advocate observation alone, while others believe that the prophylactic institution of intermittent catheterization and anticholinergic therapy may help to prevent deterioration. MATERIALS AND METHODS: A nonrandomized prospective study was instituted to compare the urological outcomes of a cohort of children who were at risk for urological deterioration on the basis of bladder-sphincter dyssynergia and/or high filling or voiding pressures. Those at risk were observed until deterioration occurred, or were placed on prophylactic intermittent catheterization with or without anticholinergic medication. RESULTS: Of 44 children at risk 35 followed by observation alone had urinary tract deterioration, whereas only 3 of 20 at risk treated with prophylactic intermittent catheterization had deterioration with time. CONCLUSIONS: Proactive bladder treatment significantly reduced the incidence of upper urinary tract deterioration and need for surgical intervention.

Cholinergic Antagonists↗

PubMed1995

Pediatric laparoscopic dismembered pyeloplasty.

We performed laparoscopic dismembered pyeloplasty in a boy with right ureteropelvic junction obstruction using 4 cannula sites, and a dismembering and reanastomosis technique identical to that used in open pyeloplasty. Interrupted sutures were placed and tied intracorporeally. A nephrostomy tube was placed under direct vision for drainage but no ureteral stent was used. Total operating time was 5 hours. The patient was discharged home 36 hours after the procedure. The nephrostomy tube was removed 10 days postoperatively after radiographic demonstration of patency and 24 hours of clamping without pain. Followup excretory urography at 6 weeks showed much less hydronephrosis and a widely patent anastomosis. Our case illustrates the technical features and feasibility of laparoscopic pyeloplasty in children, and should encourage further development of pediatric urological reconstructive laparoscopic techniques.

Child↗

PubMed1994

Meatal based hypospadias repair with the use of a dorsal subcutaneous flap to prevent urethrocutaneous fistula.

A technique using a dorsal dartos subcutaneous flap to wrap the neourethra after hypospadias repair is described. This method was used in a series of 204 meatal based repairs. Catheter drainage or diversion was not performed in any nontoilet trained child. The procedure was done on an ambulatory or 1-night hospitalization basis. No patient had a urethrocutaneous fistula. The additional covering of the neourethra with the dorsal subcutaneous flap appears to be excellent for avoiding the development of urethrocutaneous fistulas in patients with distal hypospadias.

Adolescent↗

PubMed1994

Endoscopic treatment of vesicoureteral reflux with a chondrocyte-alginate suspension.

Injection of polytetrafluoroethylene (Teflon) or collagen has been used in the endoscopic treatment of vesicoureteral reflux. Although the principle of an endoscopic treatment is valid, there are concerns regarding the long-term safety and effectiveness of these substances. In search of a different injectable material we conducted experiments using chondrocytes in a biodegradable polymer solution for the treatment of vesicoureteral reflux in an animal model. Reflux was created in 4 mini-pigs and confirmed with a cystogram. Cartilage was obtained from the auricular surface of each animal. Chondrocytes were harvested and expanded in vitro. The cells were individually quantitated and concentrated to 40 million cells per cc. The cell suspensions were mixed with a sodium alginate and calcium sulfate solution. Each pig was injected unilaterally in the subureteral region with the autologous chondrocyte suspension. The opposite ureter served as an internal control in all animals. Cystograms showed resolution of reflux in the treated side and persistence of reflux in the opposite untreated side in each instance. Excretory urograms revealed no evidence of obstruction. Histological examination of the subureteral region demonstrated cartilage. Autologous chondrocytes can be readily harvested, expanded in vitro and injected cystoscopically. The cells survive and form a cartilage nidus that is nonantigenic. This system is able to correct reflux without any evidence of obstruction.

Alginates↗

PubMed1994

Phenotypic and cytogenetic characterization of human bladder urothelia expanded in vitro.

A simple method for the harvest of bladder cell types from surgical specimens was used to generate strains of normal human urothelial cells that could be reproducibly cultivated, passaged and extensively expanded in serum-free medium. Immunostaining of the bladder epithelial cells with broadly reacting anti-cytokeratin antibodies and with an anti-cytokeratin antibody specific to cytokeratin 7, a transitional cell marker, indicated that they expressed a stable epithelial phenotype with serial passage. Low levels of immunostaining for E-cadherin and low levels of E-cadherin messenger ribonucleic acid, as determined by Northern blot analysis, and strongly positive immunostaining with an anti-vimentin antibody indicated collectively that the uroepithelial cells express a nonbarrier-forming phenotype under these culture conditions. However, when the urothelial cells were implanted subcutaneously into athymic mice on biodegradable synthetic polymers, they formed multilayered structures, suggesting that they retain the capability to differentiate in a living host. The urothelial cells proliferated in an epidermal growth factor independent manner and expressed high levels of transforming growth factor-alpha and amphiregulin messanger ribonucleic acids, suggesting the possibility of autocrine regulation of growth by epidermal growth factor-like factors. Cytogenetic analysis indicated that urothelial cells cultured for 6 passages possessed a normal chromosomal complement. These results demonstrate that primary cultures of autologous human bladder epithelial cells can be extensively expanded in vitro and, consequently, might be used in cell transplantation strategies for genitourinary reconstruction.

Amphiregulin↗

PubMed1994

Management of severe hypospadias with a 2-stage repair.

From 1986 to 1993 we treated 1,437 children with hypospadias of whom 58 had scrotal or perineal hypospadias with severe chordee and a small phallus. These patients underwent a 2-stage surgical repair. The first stage of the procedure included correction of the chordee and advancement of preputial flaps ventrally and distally to the superior aspect of the glans. After 6 to 12 months the second stage of the procedure was performed using the previously transferred preputial skin to reconstruct the glans and urethra. A second layer of subcutaneous tissue or tunica vaginalis was used in several instances. A penile nerve block and a transparent biomembrane dressing (Tegaderm) allowed for early postoperative mobilization. Excellent functional and cosmetic results were achieved. There is a subset of patients with severe proximal hypospadias, chordee and a small phallus who may benefit best from a 2-stage procedure. In these children a 2-stage repair allows for a better cosmetic appearance and a lower complication rate than a 1-stage repair with a free or vascularized graft.

Child↗

PubMed1994

Urinary levels of the renal tubular enzyme N-acetyl-beta-D-glucosaminidase in unilateral obstructive uropathy.

Elevated urinary levels of the renal tubular enzyme, N-acetyl-beta-D-glucosaminidase (NAG), have been shown to be associated with reversible tubular damage and, therefore, may serve as an indicator of tubular damage in the setting of presumed obstruction uropathy. This study compares urinary NAG levels in children with apparent upper tract obstruction with normal children to assess the sensitivity of this assay for the detection of possible renal tubular damage. The study included 40 children 3 weeks to 16 years old with unilateral ureteropelvic junction obstruction (30) or primary obstructive megaureter (10). Urine was obtained from the bladder in all children and from the renal pelvis or ureter in 30 patients at surgery. Pelvic and ureteral urinary NAG levels were consistently higher than bladder levels. In patients with ureteropelvic junction obstruction NAG levels were 7 times higher than normal (76 units per mg., p < 0.0001) and 3 times higher than normal in patients with obstructive megaureter (29 units per mg., p < 0.001). The mean bladder urinary NAG levels in patients with ureteropelvic junction obstruction (17.6 units per mg. creatinine, standard error of mean 2.01, p < 0.001) and megaureters (19.2 units per mg. creatinine, standard error of mean 3.6, p < 0.049) were elevated above control patients (10.6 units per mg. creatinine, standard error of mean 1.02). Elevated urinary NAG levels in the renal pelvis, ureter and bladder may be helpful in identifying upper tract obstruction, which if left untreated, might cause progressive renal deterioration.

Acetylglucosaminidase↗

PubMed1994

Laparoscopic evaluation of the nonpalpable tests: a prospective assessment of accuracy.

To assess diagnostic accuracy, laparoscopy and surgical exploration were prospectively performed in 104 children with 126 nonpalpable testes. Laparoscopic localization of the testis was correct in 90% (114 of 126 testes) and was nondiagnostic in 8% largely due to preperitoneal insufflation. No surgical complications occurred. Using the criteria of blind-ending vas deferens and spermatic vessels as diagnostic of an intra-abdominal vanishing testis, the accuracy of diagnosis was 100% but the inability to identify either vas or vessels was associated with intra-abdominal testes in 2 of 3 cases. Identification of canalicular vas deferens and spermatic vessels was associated with testes in 36 of 75 cases (48%). Bilateral nonpalpable testes were significantly less likely to have an absent testes (5%) than a unilateral nonpalpable testis (59%), suggesting the possibility of different pathophysiological mechanisms in those entities. Diagnosis and surgical management of nonpalpable testes were directly impacted by laparoscopy in 42 of 117 testes (36%) by identifying intra-abdominal vanishing testis, the location of an intra-abdominal testes or the need for retroperitoneal exploration when vas deferens and spermatic vessels were not found. Accurate knowledge of testis location in 97% of the testes facilitated development of an appropriate surgical strategy (that is laparoscopic/laparoscopic assisted versus open procedure).

Adolescent↗

PubMed1993

Implantation in vivo and retrieval of artificial structures consisting of rabbit and human urothelium and human bladder muscle.

The harvest of human bladder muscle and urothelial cells with subsequent growth may be useful for tissue replacement in genitourinary reconstruction. We previously reported the development of a system for the harvest, delivery and growth of rabbit urothelium in vivo using biodegradable polymers. We have now expanded and adapted this system for the harvest and in vivo implantation of human bladder urothelial and muscle cells. Synthetic polymer fibers of polyglycolic acid can serve as a scaffold and a delivery vehicle for the implantation of rabbit uroepithelial cells into athymic host animals. The polymers, which slowly degrade in vivo, allow the urothelial cells to survive at the implant site. We demonstrate that polyglycolic acid polymers support the proliferation of rabbit urothelial cells in situ and can serve as a maleable substrate for the creation of new urological structures that replace the degrading polymer fibers. We also show that human urothelial cells and bladder muscle cells, when implanted on polyglycolic acid fibers, from new urological structures in vivo composed of both cell types. The human cell-polymer xenografts can be recovered from host animals at extended times after implantation. These data suggest that feasibility of using polyglycolic acid polymers as substrates for the creation of human urothelial and muscle grafts for genitourinary reconstruction.

Animals↗

PubMed1993

Injectable alginate seeded with chondrocytes as a potential treatment for vesicoureteral reflux.

Injection of polytetrafluoroethylene (Teflon) or collagen has been used in the endoscopic treatment of vesicoureteral reflux. Although the principle of an endoscopic treatment is valid, there are concerns regarding the long-term safety and effectiveness of these substances. The goal of several investigators has been to find alternate implant materials that would be safe for human use. Toward this goal we conducted a study to determine the effect of chondrocytes using a biodegradable polymer solution as a template. Hyaline cartilage was obtained from the articular surfaces of calf shoulders and chondrocytes were harvested. Chondrocyte suspensions were concentrated to 20, 30 and 40 x 10(6) cells per cc and mixed with dry alginate powder (a biodegradable polymer) to form a gel. Twelve athymic mice were injected subcutaneously with a chondrocyte-alginate solution. Each mouse had 4 injection sites, consisting of control, 10, 15 and 20 x 10(6) chondrocyte cells (48 injection sites). Mice were sacrificed at 2, 4, 6 and 12 weeks after injection. Histological examination of the injection sites demonstrated evidence of cartilage formation in 34 of the 36 experimental injection sites. Gross examination of the injection sites with increasing time showed that the polymer gels were progressively replaced by cartilage. The ultimate size of the cartilage formed was related to the initial chondrocyte concentration injected, and appeared to be uniform and stable within each category. There was no evidence of cartilage formation in the 12 controls. Histological analyses of distant organs showed no evidence of cartilage or alginate gel migration, or granuloma formation. In conclusion, chondrocyte-alginate gel suspensions are injectable, appear to be nonmigratory and are able to conserve their volume. In addition, the use of autologous cartilage cells would preclude an immunological reaction. These preliminary studies indicate that autologous cartilage-polymer gel solutions may be potentially useful in the endoscopic treatment of reflux.

Alginates↗

PubMed1993

Laparoscopic correction of vesicoureteral reflux.

Major advances have been made in the area of laparoscopic surgery. The advantages of this approach include smaller incisions, shorter hospitalizations, a more rapid convalescence and decreased postoperative discomfort. To explore the technical feasibility of performing antireflux surgery laparoscopically, we conducted a pilot study in 4 mini-pigs in which bilateral vesicoureteral reflux had been created surgically. We applied a modification of the Lich extravesical ureteral approach to perform laparoscopic antireflux surgery. All mini-pigs underwent successful unilateral mobilization, creation of a bladder wall trough and creation of a new ureteral tunnel laparoscopically. Examinations were performed postoperatively, and then serially at 1, 2, 3 and 5 months after repair. Fluoroscopic cystograms demonstrated the resolution of reflux in the corrected ureters and persistence of reflux in the uncorrected control ureters in all animals. Excretory urography showed no evidence of obstruction. Laparoscopic correction of vesicoureteral reflux appears to be technically feasible in the animal model. Long-term followup is necessary to determine the possible applicability of this technique in humans.

Animals↗

PubMed1993

Sonography with sonicated albumin in the detection of vesicoureteral reflux.

The primary radiological procedures for diagnosing vesicoureteral reflux are fluoroscopic and radionuclide cystography. Ultrasonography, with no ionizing radiation, would be useful as a screening tool for the diagnosis of reflux due to its absence of radiation exposure. We evaluated the usefulness of ultrasonography with sonicated albumin in the diagnosis of vesicoureteral reflux. Sonicated albumin contains approximately 3 to 5 x 10(8) microspheres per ml., which are echogenic. Sonicated albumin was tested in vitro, alone, and in human and porcine urine to assess microsphere stability. Urine dilutions, specific gravity, temperature and pH were used as variables. The mode of delivery was also tested in vitro and in vivo. These studies showed that sonicated albumin microspheres were stable over a wide range of chemical variables and urine composition. Sonicated albumin produced an image of uniform echogenicity when it was pre-loaded into a Foley catheter and followed by saline infusion in vitro. Fluoroscopic cystograms, using standard radiopaque contrast media, in 5 Hanford mini-swine in which unilateral reflux had been created previously confirmed the presence of reflux unilaterally. Sonographic cystograms with various dilutions of sonicated albumin in 0.9% sodium chloride (1:100, 1:250, 1:500, 1:750 and 1:1,000) were performed. At a dilution of 1:100 sonicated albumin produced dramatic echogenicity in the bladder and refluxing ureters during sonographic imaging. The microspheres appeared to be stable for prolonged periods (more than 40 minutes), thus allowing for a careful sonographic assessment of the entire genitourinary tract. Sonicated albumin may be valuable for the sonographic detection of vesicoureteral reflux.

Albumins↗

PubMed1993

The effect of gastric augmentation on bladder function.

Gastrocystoplasty was performed in 29 female and 14 male patients 1 to 23 years old (average age 11 years). Urodynamic studies were completed in 20 patients preoperatively and within 6 months postoperatively. When postoperative studies were compared with the preoperative evaluation, it was noted that overall capacity increased an average of 220% (range 20 to 750%). Compliance also improved dramatically postoperatively. Bladder pressures increased from a mean volume of 34% of capacity preoperatively to 73% of the post-augment capacity. The average maximum filling pressure decreased by 32%, from 57 to 39 cm. water. Uninhibited contractions resolved completely in 6 of 10 patients who had them preoperatively. No one had uninhibited contractions postoperatively. Cyclical contractions of the stomach segment not exceeding 50 cm. water developed in 6 patients. The gastric patch seems to be an adequate source for improving the dynamics of a poorly functioning detrusor muscle in most patients. When a diamond-shaped patch of stomach is harvested and added to the bladder a spherical configuration is created, enhancing the storage properties. This result is in sharp contrast to other bowel segments, which must be detubularized to produce a suitable reservoir. The long-term effects of gastric augmentation remain to be determined.

Adolescent↗

PubMed1992

The prophylactic value of clean intermittent catheterization and anticholinergic medication in newborns and infants with myelodysplasia at risk of developing urinary tract deterioration.

OBJECTIVE: To determine if prophylactic use of clean intermittent catheterization and oxybutynin chloride is effective in preventing urinary tract deterioration in myelodysplastic children with high bladder pressure and detrusor-sphincter dyssynergia. DESIGN: Sequential, nonrandomized trial. SETTING: Referral-based urodynamics facility and myelodysplasia program at a major city pediatric hospital. PARTICIPANTS: Twenty-six of 71 consecutive newborns with myelodysplasia who exhibited these urodynamic findings were treated prophylactically over 5 years, whereas 56 of 105 consecutive newborns with the same findings treated during the previous 7 years were treated expectantly. INTERVENTION: Clean intermittent catheterization and oxybutynin therapy were begun when these specific urodynamic findings were detected. MEASUREMENTS AND RESULTS: Follow-up urodynamic studies and roentgenographic assessment of the urinary tract were performed periodically over 5 years. Oxybutynin eliminated uninhibited contractions in two of 14 newborns and lowered peak contractile pressure in the remaining 12. Oxybutynin also lowered bladder-filling pressure at capacity in all 12 additional neonates with only hypertonicity. Twenty-four (92%) of 26 children had normal kidney function and drainage during the observation period, two (8%) developed hydroureteronephrosis, and one of these two had vesicoureteral reflux. In a prior study of children similarly at risk who were treated expectantly, the roentgenographic appearance of the upper urinary tract had changed in 48%. Minimal side effects were noted with oxybutynin, and no adverse effects of clean intermittent catheterization were detected. CONCLUSIONS: Oxybutynin effectively reduces uninhibited contractions and lowers detrusor filling pressure, while clean intermittent catheterization allows bladder emptying at low pressures with no measurable side effects in these neonates. The overall effect maintains the integrity of the upper urinary tract in almost all myelodysplastic children at risk of urinary tract deterioration. Expectant therapy can no longer be advocated when these "at risk" children are identified because prophylactic treatment is so effective.

Boston↗

PubMed1992

The effect of obstruction on the developing bladder.

Congenital bladder obstruction causes significant immediate and long-term consequences yet its pathophysiology remains poorly understood. A model of early fetal bladder obstruction in sheep has been developed to study the response of the developing bladder to high grade obstruction, with particular emphasis on the regulation of growth and development. Congenital bladder obstruction was produced in fetal sheep at 60 days of gestation and studied at 95 days of gestation (14 sheep) or term (12 sheep). A total of 24 age-matched normal sheep served as controls. Bladders were analyzed by total weight, stereological estimation of smooth muscle cell size, number and total mass, deoxyribonucleic acid concentration, muscarinic cholinergic receptor density, myosin isoform analysis and/or passive cystometrics. Congenital bladder obstruction caused a 4.6 times increase in bladder weight at term reflecting a 5.8 times increase in smooth muscle mass. This increase was predominantly that of cellular hypertrophy and less so of hyperplasia, based upon increased cell volume, increased protein-to-deoxyribonucleic acid ratio, and no significant increase in total cell number. Muscarinic cholinergic receptor number per smooth muscle cell increased 3.2 times but it did not change relative to myosin content. The ratio of myosin heavy chain isoforms SM1:SM2 is developmentally regulated and was seen to change from 1.6 at 100 days of gestation to 1.13 at term in normals. After 5 weeks of obstruction SM1:SM2 was 1.27 and it was 1.25 at term, indicating an effect on the developmental regulation of smooth muscle. Rapid fill cystometry in vivo measured the rate of stress relaxation to assess accommodative properties. The half-decay time was increased in all 3 obstructed bladders tested to greater than 15 seconds at 50% capacity (normal less than 5 seconds), suggesting reduced compliance. This study shows that an in utero model of bladder obstruction is feasible. Congenital bladder obstruction produces a variety of structural, biochemical and functional changes in the developing bladder indicative of alterations in the regulation of growth and differentiation.

Actins↗

PubMed1992

The response of the fetal kidney to obstruction.

In a fetal ovine model the renal effects of different anatomic levels of fetal urinary obstruction were studied. Parameters of prenatal renal growth and differentiation were characterized and correlated with the patterns of renal response to in utero obstruction. Complete ureteral or urethral obstruction was produced in the sheep fetus at 55 to 60 days of gestation. Animals were delivered and sacrificed at near term (140 days), and the kidneys were removed and prepared for analysis. Parameters examined included weight, histology, glomerular number and total surface area, as well as urinary sodium, creatinine, osmolarity and N-acetyl glucosaminidase. Three patterns of response were identified, producing hydronephrotic, cystic or dysgenetic kidneys. Hydronephrotic kidneys were usually the result of bladder outlet obstruction or ureteral obstruction with spontaneous urinary decompression. These kidneys were large (20.7 gm. versus normal 10.8 gm., p less than 0.0001), with thinning of cortical parenchyma that was structurally intact. Glomerular number and surface area were normal. Cystic kidneys were large (14.2 gm., p less than 0.05) with grossly visible cysts and an effaced medulla. Cortical structure was distorted by cysts but basic elements were intact. Glomerular number and surface area were not reduced. Dysgenetic kidneys were small (3.9 gm., p less than 0.0001) with markedly abnormal cortical structure and little recognizable medulla. Histological elements similar to fetal structures were present, including cuboidal/columnar tubular epithelium and peritubular mesenchymal collars. Glomerular number and surface area were significantly less than normal (p less than 0.001). The kidneys contralateral to unilaterally obstructed kidneys were significantly larger than normal (16.2 gm., p less than 0.0001), with normal histology, glomerular number and surface area, indicating in utero contralateral renal hypertrophy. Urinary sodium was variably affected in the hydronephrotic kidneys and was identical to plasma in the dysgenetic kidneys. These results indicate the technical feasibility of in utero models of urinary obstruction. Renal growth and patterns of differentiation were markedly affected by in utero obstruction. They should be a major focus in the investigation of congenital obstructive uropathy, since normal processes of renal growth and differentiation form the basis for postnatal function.

Animals↗