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Biomedical subjects

M R Zaontz

Publications and source records attributed to M R Zaontz.

At least 19 recordsLinked to original sources
PubMed2001

Kidney transplantation in children with urinary diversion or bladder augmentation.

PURPOSE: Urinary tract anomalies or dysfunction leaves the bladder unsuitable for urine drainage in a significant proportion of children presenting for kidney transplantation. We reviewed a multi-institutional experience to determine the ramifications of kidney transplantation in children with bladder augmentation or urinary diversion. MATERIALS AND METHODS: During a 28-year period 18 boys and 12 girls 1.7 to 18 years old (mean age 12.1) received 31 kidney transplants. Cause of end stage renal disease was renal dysplasia in 8 cases, posterior urethral valves in 5, obstructive uropathy in 5, neurogenic bladder/chronic pyelonephritis in 4, spina bifida/chronic pyelonephritis in 3, prune belly syndrome in 3 and reflux in 2. RESULTS: Of the patients 17 had augmented bladder (ileum 9, ureter 5, sigmoid 2 and stomach 1), 12 had incontinent urinary conduits (8 ileum, 6 colon) and 1 had a continent urinary reservoir. Surgical complications included 1 case each of stomal stenosis, stomal prolapse, renal artery stenosis, urine leak, enterovesical fistula and wound dehiscence. Medical complications included urinary tract infection in 21 cases and metabolic acidosis in 5. A bladder stone developed in 1 patient. There was no correlation between the incidence of symptomatic urinary tract infections and type of urinary drainage. Acidosis was more common in patients with augmented bladder (4 of 17 versus 1 of 14) but there was no correlation between the bowel segment used and the occurrence of acidosis. Graft survival was 90% at 1 year, 78% at 5 years and 60% at 10 years. Etiology of graft loss included chronic rejection in 6 cases, noncompliance in 4 and acute rejection in 1. There were no deaths. CONCLUSIONS: Drainage of transplanted kidneys into an augmented bladder or urinary conduit is an appropriate management strategy when the native bladder is unsuitable or absent. Patients with kidney transplants drained into augmented bladder or urinary conduit are at increased risk for urine infection. Graft survival is not adversely affected compared to historical controls when a kidney transplant is drained into a urinary conduit or augmented bladder.

Adolescent↗
PubMed2000

La Vega slit procedure for the treatment of phimosis.

OBJECTIVES: The surgical treatment of phimosis is usually circumcision. In countries in which circumcision is not widely practiced, this approach results in a phallus that is cosmetically unacceptable. We applied a ventral slit procedure to boys with severe phimosis and achieved outstanding results. METHODS: All patients were selected during a 1-week medical mission to La Vega in the Dominican Republic during April 1997. Eight patients presented with severe phimosis. The patient age ranged from 3 to 7 years (mean 4.4). All patients were cleared by the team pediatrician before undergoing the procedure. RESULTS: Eight patients underwent the procedure without complications. The operative time was less than 10 minutes in all instances. All had excellent postoperative cosmesis, were able to retract their foreskins, and voided without difficulty. A follow-up mission to La Vega in March 1998 yielded no complications involving this group of patients. CONCLUSIONS: Unlike circumcision and the dorsal slit procedure, this approach yields a phallus that on initial appearance is indistinguishable from an uncircumcised phallus. The procedure is easily performed and should be considered in the treatment of phimosis whenever foreskin preservation is desired.

Child↗
PubMed2000

Chordee repair utilizing a novel technique ensuring neurovascular bundle preservation.

Penile chordee, with and without hypospadias, is amenable to surgical correction. The Nesbit technique of dorsal plication of the ventral tunica albuginea is effective in correcting most cases of corporal disproportion. A hazard with this approach is the potential inclusion of the dorsal neurovascular bundle, with resultant erectile and sensory dysfunction. We developed a simple technique using the Freer elevator to isolate the neurovascular bundle prior to plication. This ensures that no injury occurs to the neurovascular bundle during plication. Since 1994, 37 boys with chordee have been repaired using this approach. Their ages at the time of operation ranged from 5 months to 28 years (mean 9 months). Following standard degloving of the penis, an incision through Buck's fascia is made lateral and parallel to the neurovascular bundle at the maximum level of the chordee. A similar incision is carried out on the contralateral side. A 4-mm-wide Freer elevator is positioned under Buck's fascia while hugging the tunica albuginea. The Freer elevator slides across the midline to the contralateral side, separating Buck's fascia and underlying layers from the tunica albuginea. Following isolation of the bundle, each corporal body is plicated by creating a longitudinal incision through the tunica albuginea, which then is closed transversely with a 5-0 polydioxanone suture. Buck's fascia subsequently is closed with an absorbable suture following confirmation of chordee correction. No complications have been encountered during a mean follow-up of 21 months (range 5-51 months). No patients have required reoperation for persistent chordee. We developed a technique that elevates the neurovascular bundle prior to plication, thereby ensuring no injury to this structure. We have successfully used this modified Nesbit technique since 1994 and have had no complications. Utilization of the Freer elevator adds an estimated 5 minutes to chordee correction compared to a standard plication lateral to the neurovascular bundles. Although long-term follow-up needs to be performed to confirm any erectile or sensory advantage, this approach should be considered whenever plication is to be performed.

Adolescent↗
PubMed1998

Epidermolysis bullosa: a review of the associated urological complications.

PURPOSE: Epidermolysis bullosa is a devastating rare disorder that rarely presents with urological complications. We report our experience with and review the literature on this disorder. MATERIALS AND METHODS: Two brothers with epidermolysis bullosa presented to our center with severe dysuria and urinary tract obstruction caused by meatal stenosis. The obstruction was temporarily relieved by meatotomy but recurrent obstructive skin blistering with severe dysuria required ureterosigmoidostomy for palliation of symptoms. RESULTS: Both children tolerated ureterosigmoidostomy well with 1 requiring bicarbonate supplementation for metabolic acidosis. Ureterosigmoidostomy greatly improved quality of life, and both children have complete symptom relief. CONCLUSIONS: Epidermolysis bullosa is usually a severe illness associated with a poor prognosis. Crippling urological symptoms may develop due to recurrent skin blistering causing severe dysuria and secondary obstruction. Ureterosigmoidostomy, despite its complications, provides significant palliation for patients with recalcitrant symptoms.

Child, Preschool↗
PubMed1998

Lessons learned about contralateral reflux after unilateral extravesical ureteral advancement in children.

PURPOSE: The development of contralateral reflux after unilateral antireflux surgery has spawned interest and controversy regarding etiology and management issues. We evaluate our experience to understand better the issues surrounding contralateral reflux. MATERIALS AND METHODS: We retrospectively reviewed the records of all children seen in a 7-year period who underwent unilateral extravesical ureteral advancement performed by one of us (M. R. Z.) at our institution. RESULTS: A total of 43 children a mean of 50.5 months old underwent unilateral reimplantation. The male-to-female ratio was 12:31. In 12 children contralateral reflux had resolved preoperatively. Overall contralateral reflux developed in 5 patients (11.6%) after unilateral extravesical ureteral advancement. In 1 child in whom new onset contralateral reflux developed on 1 side reflux resolved by 10 months with observation. In 8 of the 12 children (66%) with a history of resolved contralateral reflux there was no recurrence. In 4 of the 12 children recurrent contralateral reflux completely resolved by 14 months postoperatively with only observation. In these 4 patients initial reflux had been grades II and IV in 2 each. To date all fully evaluable reflux in children with previous contralateral reflux recurred has resolved. CONCLUSIONS: The recurrence of contralateral reflux after unilateral reimplantation that is expected in a small number of children resolves in the majority, if not in all, with conservative management. We believe that children should not be offered bilateral reimplantation for unilateral reflux and a history of resolved contralateral reflux. If contralateral reflux recurs, it will most likely resolve with time.

Child, Preschool↗
PubMed1998

Multicenter experience with the Mitchell technique for epispadias repair.

PURPOSE: We present a multicenter experience using the Mitchell epispadias technique to determine if satisfactory results could be obtained by various pediatric urologists at multiple centers using the same technique to repair epispadias. This particular technique involves complete disassembly of the penis into 2 separate hemicorporeal glandular bodies and a separate urethral plate, and relies on the unique blood supply to the epispadiac phallus. MATERIALS AND METHODS: A total of 17 boys 11 months to 21 years old underwent the Mitchell procedure for epispadias at 4 institutions by 6 different surgeons between 1994 and 1996. One patient in this group had undergone prior epispadias repair, which had failed. RESULTS: At followup (mean 13.5 months) 3 boys had pinpoint penopubic fistulas, which resolved spontaneously in 2. The 21-year-old patient had a complete wound dehiscence. All boys with intact repairs have straight erections, orthotopic meatus and satisfactory appearances. There were 15 boys with a conical glans appearance and 1 exhibiting glandular disproportion. There was 1 episode of postoperative pyelonephritis. CONCLUSIONS: The Mitchell technique for repair of epispadias is reproducible and successful in the hands of pediatric urologists from different centers. Chordee is reliably corrected, erectile function preserved, the urethra ventrally situated in an anatomically precise fashion and satisfactory cosmesis achieved.

Adolescent↗
PubMed1997

Abnormalities of the external genitalia.

This article discusses the general nuances of hypospadias, exstrophy/epispadias, and ambiguous genitalia. Embryologic considerations, etiologic factors, anatomy, associated anomalies, and timing of referrals and surgery are discussed.

Abnormalities, Multiple↗
PubMed1997

Rat renal allograft tolerance is associated with local TGF-beta and absence of IL-2r expression within chimeric immunocytic foci.

Tolerance was induced in Lewis (LEW) rat renal allograft recipients of Brown Norway kidneys by multiple pretransplant donor-blood transfusions and prior limited cyclosporine A. Rat renal allograft tolerance was associated with the induction of systemic donor T cells (10%), an early phase of nonspecific suppressor-cell generation, followed by maturation of systemic antigen-specific suppressor cells, and renal cellular infiltrates that develop long-term in situ in the kidney graft model. It was hypothesized that these infiltrates represent chimeric immunocytic foci that are locally regulated via a TGF-beta-dependent mechanism. Both immunohistochemical staining and digital image analysis for cellular and extracellular TGF-beta, IL-2 receptor (CD25), and the BN Class I-MHC marker (OX-27) were performed. Control rejecting (REJ) kidneys did not demonstrate any differences with respect to levels of infiltrating immunocyte area vs long-term surviving (TOL) kidneys (3.9% vs 4.5%, P = .303). Immunostaining with the BN Class I MHC marker (OX-27) demonstrated high levels of chimerism within immunocyte foci of the tolerant grafts (OX-27 BN+immunocytes 49.0% +/- 5.1%). In situ cellular IL-2 receptor (CD25) expression was demonstrated in REJ kidney infiltrates but not within TOL immunocytic infiltrating foci, when measured as percent of total lymphocytes (REJ = 5.0% vs TOL = 0.4%, P = .031). Conversely, TGF-beta expression was significantly higher in immunocytes of TOL kidneys when measured as the number of DAB chromogen-staining pixels per total immunocyte area (TOL = .076 vs REJ = .047, P = .003). In conclusion, these results suggested that stable mixed immune chimerism (SMIC) plays an important role in DST-CyA-induced tolerance in situ. SMIC-induced tolerance may involve a local TGF-beta-dependent mechanism that is associated with in situ TGF-beta (+) and IL-2r (-) immunocytes.

Animals↗
PubMed1997

Stent-free Thiersch-Duplay hypospadias repair with the Snodgrass modification.

PURPOSE: Incision of the glanular urethral plate (the Snodgrass modification) permits tubularization of the neourethra in the Thiersch-Duplay fashion when anatomy would otherwise preclude a tension-free anastomosis and necessitate another operative technique for hypospadias repair. To take advantage of these cosmetic benefits without the potential morbidity associated with indwelling catheters, we performed a stent-free Thiersch-Duplay repair incorporating the Snodgrass modification. MATERIALS AND METHODS: The Thiersch-Duplay hypospadias repair was combined with the Snodgrass modification. Hinging the urethral plate was necessary when the glanular groove was too shallow to perform a standard Thiersch-Duplay repair. RESULTS: Stent-free repairs were performed in 33 children 0.47 to 2.66 years old (mean age plus of minus standard deviation 0.98 +/- 0.47). Followup was obtained in 31 children. There was no postoperative urinary retention, fistulas or meatal stenosis. No unusual or prolonged discomfort distinguished these children from those who underwent a standard Thiersch-Duplay repair. CONCLUSIONS: Excellent cosmetic results can be anticipated irrespective of the preoperative glans configuration. Incision of the glanular urethral plate can be performed safely as an adjunct to a modified Thiersch-Duplay hypospadias repair without postoperative indwelling catheters.

Child, Preschool↗
PubMed1996

The influence of small functional bladder capacity and other predictors on the response to desmopressin in the management of monosymptomatic nocturnal enuresis.

PURPOSE: The relationship of functional bladder capacity as well as other variables to the responsiveness to desmopressin in children with monosymptomatic nocturnal enuresis was investigated. MATERIALS AND METHODS: A total of 95 children 8 to 14 years old with monosymptomatic nocturnal enuresis (6 or more of 14 nights wet) were evaluated in a double-blind study followed by open label crossover extension using 20 to 40 mcg. desmopressin. Evaluated predictors of response included patient age, gender, race, family history, number of baseline wet nights, urine osmolality parameters and maximum functional bladder capacity (as a percent of predicted bladder capacity based on the formula, patient age + 2 x 30 = cc). Responders to desmopressin were classified as excellent (2 or less of 14 nights wet) or good (50% or greater decrease but more than 2 of 14 nights wet) and nonresponders were defined by a less than 50% decrease in wet nights. RESULTS: Of the 95 patients 25 (29.5%) achieved an excellent response to desmopressin and 18 (18.9%) had a good response for a cumulative response rate of 45.3%. The remaining 52 patients (54.7%) were nonresponders. There were no significant differences between responders and nonresponders in regard to gender, race, positive family history or baseline urine osmolality parameters. Response to desmopressin was associated with older age, fewer baseline wet nights and larger bladder capacity. Patients with a functional bladder capacity greater than 70% predicted bladder capacity were 2 times more likely to respond to desmopressin. CONCLUSIONS: The responsiveness of children with nocturnal enuresis to desmopressin is adversely affected by reduced functional bladder capacity. The results of this study have implications regarding the potential use of combination pharmacotherapy with desmopressin and an anticholinergic for enuretic patients who are nonresponsive to single drug therapy.

Adolescent↗
PubMed1995

Cryptorchidism, pediatricians, and family practitioners: patterns of practice and referral.

A multicenter study was undertaken to study cryptorchidism and the timing of orchidopexy. A total of 329 children underwent surgery at a mean age of 4.2 years; 17% of the surgery was performed between 6 and 12 months of age, 25% between 5 and 10 years of age, and 9% during or after puberty. Only 30% of the pediatricians and 14% of the family practitioners recommended orchidopexy between 6 and 12 months of age, and 17% of these referring physicians recommended waiting until 3 to 10 years of age. Improved education is needed if current recommendations for early orchidopexy are to be achieved.

Adolescent↗
PubMed1993

Use of kidney internal splint/stent (KISS) catheter in urinary diversion after pyeloplasty.

We report on the use of a new catheter, the kidney internal splint/stent (KISS), to facilitate renal urine drainage following pyeloplasty. The catheter combines the desirable qualities of nephrostomy tube diversion, anastomotic stent, and trocar placement in a single tube. The special construction of its lumen diminishes the likelihood of obstructed drainage. Our experience using the KISS catheter with 31 patients undergoing pyeloplasty shows it provides effective internal and external urinary diversion.

Adolescent↗
PubMed1993

Fate of renal allografts transplanted in patients with urinary diversion.

Fifty-five kidneys were transplanted into 50 patients with supravesical urinary diversion at 16 transplant centers between 1970 and 1991. Of the 32 males and 18 females, 40 were adults (> or = 18 years) and 10 were less than 18 years old at the time of first transplant. Mean follow-up was 7.8 years. At last follow-up, 94% of recipients were alive and 73% of the kidneys were functioning. Fifteen kidneys were lost: 9 to rejection, 3 to noncompliance, and 3 patients died with a functioning kidney. Ten (18%) transplants were followed by surgical complications. Twenty-four (44%) were followed by medical complications of which urinary tract infection was most common. Recipients age 18 or younger had more urinary tract infections than older patients. No patient had urinary stones and no patient required medical treatment for metabolic abnormalities. We conclude that drainage of kidney transplants into a supravesical urinary diversion is an effective treatment for end-stage renal disease patients without adequate urinary bladders.

Adult↗
PubMed1992

Favorable experience with pre-emptive renal transplantation in children.

We retrospectively examined our experience with live-related donor kidney transplants in 66 children during the 7-year period 1984-1990. We compared the clinical courses of 26 children who did not receive any dialytic therapy prior to transplantation with 40 children who were dialyzed (27 via peritoneal dialysis and 13 via hemodialysis). We did not find any statistically significant differences in patient or graft survival between these three groups with a follow-up period of 6-87 months. Based on our results, we conclude that pre-emptive transplantation is an acceptable treatment for children who will inevitably require renal replacement therapy.

Adolescent↗