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Dive into the research topics where Michael P. Leonard is active.

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Featured researches published by Michael P. Leonard.


The Journal of Urology | 1991

Endoscopic injection of glutaraldehyde cross-linked bovine dermal collagen for correction of vesicoureteral reflux.

Michael P. Leonard; Douglas A. Canning; Craig A. Peters; John P. Gearhart; Robert D. Jeffs

From November 1986 through May 1989, a Food and Drug Administration approved investigational study was done to assess the safety and efficacy of glutaraldehyde cross-linked bovine dermal collagen in the endoscopic treatment of vesicoureteral reflux. Over-all, 57 patients (92 ureters) were treated. The majority of ureters (68.5%) had grade II to III/V vesicoureteral reflux (international classification). One treatment was given in 61.4% of the patients, while 33.3% required 2 and 5.3% required 3 treatments. Nonduplicated/primarily refluxing ureters comprised 68.5% of the total, while 13% were duplex/primarily refluxing and 18.5% were surgical failures. The procedures were performed on an outpatient basis in all but 3 patients. Patients were evaluated by voiding cystourethrogram and renal/bladder sonography before and after treatment at 1 month and 1 year. Cure at 1 month after the last treatment was achieved in 75% of the ureters. Among the ureters cured at 1 month the cure persisted in 79% at 1 year after treatment. Cure at 1 year was achieved in 65% of all ureters evaluated, regardless of the status at 1 month. Procedure-related morbidity was minimal and there were no adverse reactions to the implant substance. Thus, glutaraldehyde cross-linked bovine dermal collagen appears to be safe and effective in the endoscopic treatment of vesicoureteral reflux.


The Journal of Urology | 1990

Local tissue reaction to the subureteral injection of glutaraldehyde cross-linked bovine collagen in humans.

Michael P. Leonard; Douglas A. Canning; Johnathan I. Epstein; John P. Gearhart; Robert D. Jeffs

Although the technique of subureteral injection has been widely accepted as an alternative to reimplantation in the treatment of vesicoureteral reflux, the choice of the material to be used is controversial. We have used glutaraldehyde cross-linked bovine collagen to correct vesicoureteral reflux within the context of a Food and Drug Administration approved investigational study. We report the local tissue reaction to the implanted collagen in 7 patients who underwent reimplantation 3 to 19 months after failed endoscopic therapy. Glutaraldehyde cross-linked bovine collagen engendered a minimal localized inflammatory reaction without causing granuloma formation. Subsequent reimplantation was not hindered by the presence of the implant materials.


The Journal of Urology | 1990

Continent Urinary Reservoirs in Pediatric Urological Practice

Michael P. Leonard; John P. Gearhart; Robert D. Jeffs

During the last 3 years 20 patients (median age 8 years) have undergone construction of a continent urinary reservoir at our pediatric urology service. Of the patients 12 had failed exstrophy reconstruction, 7 had myelodysplasia with a neurogenic bladder and 1 had extensive bladder damage as a result of a previous operation. In 5 patients a continent reservoir was constructed after cystectomy performed in early childhood. Techniques of reconstruction included the Mitrofanoff procedure (4 patients), a modification of the Indiana pouch (12), a modification of the Benchekroun procedure (2), the use of the appendix in situ as a continence mechanism (2) and a modified Kropp procedure using a duplicate vagina for catheterization (1). The morbidity from these procedures was acceptable and consisted primarily of chronic diarrhea (4 patients), stone formation within the pouch (5) and the need to revise the continence mechanism (7). All but 1 patient maintained stable or improved upper tracts after diversion. Over-all, 85% of the patients experienced diurnal continence on an intermittent catheterization regimen, while 75% were dry at night. The plicated/intussuscepted ileal nipples required revision because of difficulty with catheterization (7 patients) and urinary leakage. We currently favor the use of the Benchekroun or Mitrofanoff techniques for the ease of construction and minimal requirements for revision.


The Journal of Urology | 1993

PROSTATE SIZE AND CONFIGURATION IN ADULTS WITH BLADDER EXSTROPHY

John P. Gearhart; Andrew Yang; Michael P. Leonard; Robert D. Jeffs; Elias A. Zerhouni

A total of 13 men born with classical bladder exstrophy underwent magnetic resonance imaging examination of the pelvis to evaluate the size and configuration of the prostate and pelvic organs. Mean patient age was 25.2 years (range 19 to 38). Of the patients 4 are voiding per urethram and 9 have undergone urinary division. Measurements included prostate volume, weight and maximum axial cross sectional area; pubic diastasis, and seminal vesicle size. The mean prostatic cross sectional area was 10.1 +/- 3.4 cm.2. The mean estimated prostatic volume and weight were 20.7 +/- 8.2 cc and 21.7 +/- 8.6 gm., respectively. The mean seminal vesicle length and width were 2.1 +/- 0.99 and 1.1 +/- 0.38 cm., respectively. The volume, weight and maximum cross sectional area of the prostate appear normal compared to published norms. In none of the patients did the prostate extend circumferentially around the urethra and the urethra was anterior to the prostate in all patients. Also, the puborectalis muscle group was widely separated and only provided lateral support of the prostate in patients who were continent and who had undergone prior posterior iliac osteotomy. Thus, the attainment of continence in this complex group of patients is multifactorial and prostate growth as evaluated by magnetic resonance imaging may not influence continence in these patients.


Pediatric Surgery International | 1991

Endoscopic treatment of vesicoureteral reflux using cross-linked bovine dermal collagen

Marc Cendron; Michael P. Leonard; John P. Gearhart; Robert D. Jeffs

To assess the efficacy of endoscopic treatment of vesicoureteral reflux (VUR) with cross-linked bovine collagen, 59 patients with grade I through V VUR were evaluated and treated. Follow-up consisted of a voiding cystourethrogram and renal ultrasound at 1 month and 1 year with urinalysis and urine culture. Repeat treatment was carried out in cases in which no resolution of the reflux was noted up to three times. The procedure was performed on an outpatient basis in 56 patients and was not associated with any major morbidity or mortality. Cure at 1 month was observed in 75% of ureters treated; cure persisted in 79% of these ureters at 1 year. The overall cure rate was 65% at 1 year. Given the simplicity of the procedure, its low complication rate, and overall success in the majority of patients, we feel that endoscopic treatment of VUR with cross-linked bovine dermal collagen is a safe and effective method and worthy of further study to enhance its efficacy.


Urology | 1991

Pediatric testicular tumors: The Johns Hopkins experience

Michael P. Leonard; Robert D. Jeffs; Brigid G. Leventhal; John P. Gearhart

Testicular neoplasms constitute 1 percent of all childhood malignancies and rank eighth in childhood cancer mortality. From 1970 to 1988, 25 testicular tumors in children eighteen years and under were seen. The majority of the patients were white (88%). Pathologic analysis of the tumors revealed that 68 percent were germinal and 32 percent were nongerminal. Staging was undertaken in all patients with serum markers, chest x-ray film, and computerized tomography scans or lymphangiography. All patients underwent radical orchiectomy, and further therapy was given dependent on tumor type and stage. The survival among this cohort was excellent, with only 3 patients succumbing to their disease. Detailed results of treatment, and approaches to avoid excess treatment morbidity are reviewed.


Urology | 1995

EPISPADIAS WITH PHIMOSIS: AN UNUSUAL VARIANT OF THE CONCEALED PENIS

Padraic D. McCahill; Michael P. Leonard; Robert D. Jeffs

An unusual variant of concealed penis is described. Two neonates with epispadias and complete phimosis were diagnosed at birth and underwent delayed repair. These 2 cases are the 5th and 6th such reports in the literature. This anomalys possible embryogenesis is reviewed.


The Journal of Urology | 1991

Use of the Benchekroun Hydraulic Valve as A Catheterizable Continence Mechanism

David M. Quinlan; Michael P. Leonard; Charles B. Brendler; John P. Gearhart; Robert D. Jeffs

Problems with continence and access for catheterization with previous continent stoma techniques have led us to search for an alternate method. We report our initial experience with the Benchekroun hydraulic valve in 9 patients. Five patients underwent creation of an ileocolic bladder: for myelodysplasia in 1, after cystectomy for bladder cancer in 2 and for exstrophy in 2. Two patients underwent conversion from an uncatheterizable Indiana pouch because of exstrophy (1) and interstitial cystitis (1). Two patients underwent small bowel augmentation of a small, poorly compliant bladder with an abdominal Benchekroun stoma: 1 had exstrophy and 1 had myelodysplasia. Patient age ranged from 7 to 63 years. Two patients had de novo creation of an ileocolic bladder, whereas 7 had bladder or previous bowel conduits incorporated in the continent reservoirs. At up to 20 months of followup all patients had diurnal and nocturnal continence, and none had experienced serious long-term complications. Problems were encountered in 5 patients. One patient had a valve fistula that was surgically revised. One patient experienced transient difficulty with catheterization when the reservoir was overdistended and a false passage developed. Three patients had stomal stenosis and require periodic dilation. We believe the Benchekroun hydraulic valve to be a useful adjunct in the construction of a continent urinary reservoir. It is easy to construct, provides reliable continence and is easy to catheterize. Furthermore, it may be applied to standard ileocolic bladders either de novo or as a salvage procedure for failed efferent limbs.


Journal of Pediatric Surgery | 1991

Reoperative ureteral reimplantation: Strategies for management

John P. Gearhart; Michael P. Leonard

Ureteral reimplantation is a procedure commonly performed by both urologists and pediatric surgeons. Although the vast majority are successful, there are some patients in whom technical considerations or bladder/ureteral abnormalities militate against success. We review our experience in 19 patients with multiple failed reimplants. The reasons for their failure, the investigations required to document such, and the management of these difficult problems will be discussed. In our hands, 95% of these patients ultimately became reflux-free and nonobstructed.


The Journal of Urology | 1990

Nuclear morphometry as a prognostic indicator for genitourinary rhabdomyosarcoma : a preliminary investigation

Michael P. Leonard; Alan W. Partin; Jonathan I. Epstein; Robert D. Jeffs; John P. Gearhart

Rhabdomyosarcoma of the urogenital tract is a malignant mesenchymal tumor seen primarily in childhood. Multimodal therapy, encompassing surgery, radiotherapy and chemotherapy, has dramatically improved the survival of patients with this disease. However, the quest for markers of tumor aggression is important to decrease the morbidity of treatment given to patients with good prognosis tumors, while at the same time intensifying treatment of tumors with poor prognosis. Using archival tumor specimens from 13 patients with genitourinary rhabdomyosarcoma, a multivariate analysis of multiple nuclear shape descriptors was done with the Hopkins Morphometry System. Three nuclear shape descriptors clearly separated patients with no evidence of disease recurrence or progression from those with recurrent disease, progressive disease or death of disease. These nuclear shape descriptors were standard error of the chain code standard deviation analysis (p = 0.010), range of the feret ellipticity distribution (p = 0.016) and standard error of the chain code range analysis (p = 0.037). With multivariate analysis these shape descriptors taken together separated patients with good and poor prognoses to a level of significance of p = 0.007. Thus, nuclear morphometric analysis may prove to be useful as an individual prognostic indicator in childhood genitourinary rhabdomyosarcoma and warrants further analysis in a much larger, blinded, controlled study.

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Luis Guerra

Children's Hospital of Eastern Ontario

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Alan W. Partin

Johns Hopkins University

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Craig A. Peters

Johns Hopkins University School of Medicine

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Jonathan I. Epstein

Johns Hopkins University School of Medicine

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Daniel Francis Gunn Costa

Children's Hospital of Eastern Ontario

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Joseph de Nanassy

Children's Hospital of Eastern Ontario

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