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Biomedical subjects

D A Canning

Publications and source records attributed to D A Canning.

At least 19 recordsLinked to original sources
PubMed2001

Buccal mucosal grafts: lessons learned from an 8-year experience.

PURPOSE: We evaluated our 8-year experience with buccal mucosal grafts in complex hypospadias and epispadias repair. MATERIALS AND METHODS: We reviewed the records of 29 patients in whom a total of 30 buccal mucosal grafts were placed as part of urethral reconstruction between 1991 and 1999. At surgery 16 tubes and 14 onlays were constructed and 24 of 30 repairs involved the meatus. All patients were followed at least 6 months postoperatively (median 5.3 years). Beginning in 1995 meatal design was enlarged to a racquet handle shape and patients were asked to perform meatal self-dilation for 6 months postoperatively. RESULTS: Complications developed in 17 of our 30 cases (57%) and reoperation was done in 10 (33%). All complications were evident by 11 months postoperatively except 1 that presented as recurrent stricture disease at 3 years. Complications developed in 5 and 12 of 15 patients who underwent surgery between 1995 and 1999, and before 1995, respectively (p = 0.027). No patient has had meatal stenosis since 1995. Complications included meatal stenosis in 5 cases, stricture in 7, glanuloplasty, meatal and complete graft breakdown in 1 each, and fistula in 2. Onlays were more likely to result in stricture than tube grafts (6 of 14 cases versus 1 of 16, p = 0.034). CONCLUSIONS: The complication and reoperation rates of buccal mucosal grafts are 57% and 33% at 5 years of followup. Changes in meatal design and temporary postoperative meatal dilation have improved the outcome in the last 5 years. Buccal mucosa remains a good choice in patients who require extragenital skin for urethral reconstruction.

Adolescent↗
PubMed2001

The decompensated detrusor V: molecular correlates of bladder function after reversal of experimental outlet obstruction.

PURPOSE: Calcium ion homeostasis has a significant role in smooth muscle function. Its regulation requires complex storage and release mechanisms via ion pumps and channels located within intracellular storage sites (sarcoplasmic reticulum) and at the plasma membrane. We have previously reported a dramatic loss of the 2 major sarcoplasmic reticulum proteins sarcoplasmic endoplasmic reticulum calcium magnesium adenosine triphosphatase (SERCA2) and the ryanodine sensitive ion channel, also called the ryanodine receptor, after outlet obstruction. In our current study we investigated the correlation of the expression of these 2 major sarcoplasmic reticulum components with bladder function recovery after the reversal of outlet obstruction. METHODS AND METHODS: Standard partial bladder outlet obstruction was created in adult New Zealand White rabbits. Voiding patterns were monitored 2 and 4 weeks postoperatively, and rabbits were selected for outlet obstruction reversal based on a voiding pattern consistent with a decompensated state, as indicated by a frequency of greater than 30 voids daily and an average voided volume of less than 4 cc. Bladder biopsy was done when outlet obstruction was reversed. Voiding performance was monitored postoperatively and the animals were sacrificed 2 weeks later. Voiding patterns and muscle strip studies enabled us to define 2 functional outcome categories after reversal, namely normal versus minimally improved. Microsomal membrane protein fractions were prepared from the same bladder tissues before and after reversal, and probed by Western blot analysis for SERCA2 and ryanodine receptor expression. RESULTS: Western blot analysis revealed a major loss of SERCA2 and ryanodine receptor expression at the time of reversal and biopsy. In 65% of bladders obstruction reversal resulted in a normalized voiding pattern with a recovery of ryanodine receptor expression that was 15% to 65% of control values. In contrast, in the 35% of bladders with persistent voiding symptoms there was minimal recovery of ryanodine receptor expression. SERCA2 expression increased slightly in each group after reversal but did not differ in bladders with normalized versus improved function. CONCLUSIONS: Bladder decompensation is highly associated with a loss of sarcoplasmic reticulum function. Furthermore, the decompensated detrusor recovers function after obstruction reversal, which is associated with the recovery of these sarcoplasmic reticulum components.

Animals↗
PubMed2001

The decompensated detrusor IV: experimental bladder outlet obstruction and its functional correlation to the expression of the ryanodine and voltage operated calcium channels.

PURPOSE: Calcium ion homeostasis has a significant role in smooth muscle function. Its regulation requires complex storage and release mechanisms via ion pumps and channels located within intracellular storage sites (sarcoplasmic reticulum) and at the plasma membrane. A prominent component of the sarcoplasmic reticulum is the ryanodine sensitive ion channel which releases calcium from the sarcoplasmic reticulum into the cytosol. At the level of the plasma membrane the voltage operated calcium channel (dihydropyridine sensitive) serves to allow an influx of extracellular calcium. Our prior studies have shown a loss of sarcoplasmic endoplasmic reticulum Ca++Mg++ATPase expression following outlet obstruction. In this study we correlate ryanodine and voltage operated calcium channel protein expression with bladder function following partial outlet obstruction. MATERIALS AND METHODS: Standardized partial bladder outlet obstructions were created in adult New Zealand white rabbits, which were divided into control, sham operated and obstructed groups. Muscle strip studies further subcategorized the obstructed group into compensated (force greater than 50% of control) and decompensated (force less than 50% of control) and were correlated with in vivo determinations of voiding frequency and voided volumes. Microsomal membrane protein fractions were prepared from the same bladder tissue and were used for Western blot analysis using specific monoclonal antibodies. RESULTS: Increased voiding frequency and decreased voided volumes correlated with the definitions of compensated and decompensated. The Western blots revealed a near disappearance of ryanodine expression in the decompensated group with minimal changes in the expression of the voltage operated calcium channel. CONCLUSIONS: Bladder performance as measured in vivo and in vitro after outlet obstruction is influenced in part by smooth muscle cell ability to maintain calcium homeostasis via the sarcoplasmic reticulum. Bladder decompensation is highly associated with a loss of sarcoplasmic reticulum function with lesser changes taking place in those calcium regulatory proteins at the plasma membrane.

Animals↗
PubMed2001

Constipation as a cause of scrotal pain in children.

Six boys with scrotal pain and constipation were seen at our hospital within the past 5 years. All boys had no clinical findings of structural or infectious derangements, and experienced relief of testicular symptoms after evacuation of the fecal mass. The association between constipation and scrotal pain has not been previously reported, and may represent direct neural stimulation or chronic inflammation of testicular structures in patients with dysfunctional voiding. Recognition of the association between constipation and subacute or chronic scrotal pain can guide the clinician towards appropriate therapy for these patients.

Abdominal Pain↗
PubMed2001

Laser tissue soldering for hypospadias repair: results of a controlled prospective clinical trial.

PURPOSE: Laser tissue soldering has been shown to provide safe and effective tissue closure by creating an immediate leak-free anastomosis with minimal scar formation. We compared the results of laser tissue soldering and conventional suturing for hypospadias repair. MATERIALS AND METHODS: A consecutive group of 138 boys 4 months to 8 years old (mean age 15 months) was divided into a standard suturing (84) and a sutureless laser (54) hypospadias repair group. Urethral repair was defined as simple (Thiersch-Duplay or Snodgrass) and complex (onlay island flap or tube) in 101 and 37 cases, respectively. Laser tissue soldering was performed with 50% human albumin solder doped with 2.5 mg./ml. indocyanine green dye using an 808 nm. diode laser at 0.5 W. In the laser group sutures were used for tissue alignment only. At surgery neourethral and penile length, operative time for neourethral construction and the number of sutures or throws were measured. Postoperatively patients were examined for complications of wound healing, stricture or fistula. RESULTS: Mean patient age, urethral defect severity, type of repair, neourethral length and stenting time plus or minus standard error of mean were not significantly different in the 2 groups. Mean operative time was a fifth as long for laser tissue soldering in simple and complex hypospadias repair compared to controls (1.5 +/- 0.1 and 5.1 +/- 0.3 versus 8.5 +/- 0.8 and 26.7 +/- 1.7 minutes, respectively, p <0.001). The mean number of sutures used for tissue alignment in the laser group for simple and complex repair was significantly less than in controls (3.0 +/- 0.2 and 8.2 +/- 0.6 versus 8.5 +/- 0.8 and 23.2 +/- 1.5, respectively, p <0.001). All patients were followed a mean of 12 months (minimum 6, maximum 22). The complication rate was 4.7% in the laser group and 10.7% in controls with fistula in 2 of 54 cases, and fistula and meatal stenosis in 7 and 2 of 84, respectively. CONCLUSIONS: These preliminary results indicate that laser tissue soldering for hypospadias repair may be performed in almost sutureless fashion and more rapidly than conventional suturing. The ease of the laser technique and the lower complication rate in the laser group indicate that laser tissue soldering is an acceptable means of tissue closure in hypospadias repair.

Child↗
PubMed2001

Abnormal germ cell development in cryptorchidism.

BACKGROUND: Previous studies suggest that two fundamental, probably androgen-dependent, steps in maturation of germ cells normally occur in the prepubertal testis: the disappearance of gonocytes (the fetal stem cell pool) and the appearance of adult dark spermatogonia (the adult stem cell pool) at 2-3 months of age and the appearance of primary spermatocytes (the onset of meiosis) at 4-5 years. Previous studies of small series of cryptorchid boys suggest that both steps are defective in undescended testes and to a lesser degree in descended testes contralateral to unilaterally undescended testes. The purpose of this study is to confirm the previous findings of defective germ cell maturation in a large series of boys with unilateral undescended testes. PATIENTS: Seven hundred and sixty-seven boys with unilateral cryptorchidism who had orchidopexy and bilateral testicular biopsies between birth and 9 years of age were studied. MATERIALS AND METHODS: Total and differential germ cell counts were performed on semithin histologic sections of the biopsies. The results from the undescended and contralateral descended testes were compared using the Wilcoxon signed-rank test and the Wilcoxon-Whitney-Mann U test. RESULTS: Gonocytes failed to disappear and adult dark spermatogonia failed to appear in undescended testes under 1 year of age indicating a defect in the first step in maturation at 2-3 months resulting in failure to establish an adequate adult stem cell pool. Primary spermatocytes failed to appear in undescended testes and appeared in only 19% of contralateral descended testes at 4-5 years of age indicating a defect in the onset of meiosis. CONCLUSION: Unilaterally undescended testes fail to establish an adequate adult stem cell pool which normally occurs at 2-3 months of age and fail to establish adequate meiosis which normally occurs at 4-5 years of age. Similar but less severe changes are seen in the contralateral descended testes. Defects in the two pubertal steps in germ cell maturation are associated with reduced total germ cell counts.

Biopsy↗
PubMed2001

Hormonal therapy for the subfertility of cryptorchidism.

BACKGROUND: The subfertility of cryptorchidism correlates with severely reduced total germ cell counts in prepubertal testicular biopsies of undescended testes. Reduced total germ cell counts are associated with defects in the two prepubertal steps in maturation and proliferation in germ cells: first, the transformation of the fetal stem cell pool (gonocytes) into the adult stem cell pool (adult dark spermatogonia) at two to three months of age and, second, the transformation of adult dark spermatogonia into primary spermatocytes (meiosis) at 4-5 years. The defects in maturation are associated with blunting of the normal surges in gonadotropins and testosterone. Prepubertal treatment with gonadotropin-releasing hormones would theoretically trigger normal germ cell maturation and proliferation and thereby improve total germ cell counts and improve fertility. Prepubertal treatment of cryptorchidism with the GnRH analogue Buserelin has resulted in improved total germ cell counts and improved spermiograms. The purpose of this report is to describe the results of treatment of cryptorchidism with the GnRH analogue Naferelin. PATIENTS: Twelve boys with cryptorchidism, 6 unilateral and 6 bilateral, and severely reduced germ cell counts in testicular biopsies were treated with Naferelin following successful orchidopexy and bilateral testicular biopsies. Response of the total germ cell counts was assessed in follow-up bilateral biopsies within 5 months of completing the hormonal therapy. RESULTS: Eight of the 12 boys (5 of the 6 with unilateral and 3 of the 6 with bilateral cryptorchidism) showed improvement in the total germ cell counts in one or both testes. All 8 had a poor prognosis for fertility pretreatment and a good prognosis for fertility posttreatment. Of the 5 with unilateral cryptorchidism who improved, 2 showed improvement in both testes; and 3, only in the contralateral descended testes. All 3 of the boys with bilateral cryptorchidism who improved showed improvement in both testes. Testes with absence of germ cells and older patients tended to show no improvement. Of the 6 contralateral descended, 5 (83%) improved, and of the 18 undescended testes, 8 (44%) improved. CONCLUSIONS: In this preliminary study, Naferelin therapy appears to induce improvement in the total germ cell counts and the prognosis for future fertility in 75% of patients.

Child↗
PubMed2001

The histopathology of iatrogenic cryptorchid testis: an insight into etiology.

PURPOSE: Iatrogenic undescended testis may develop after inguinal hernia repair, presumably as a result of mechanical tethering of the testis or cord in scar tissue. Because some true cryptorchid testes appear to be completely descended at birth and later ascend during childhood, some iatrogenic undescended testes may be low lying undescended testes. To determine whether iatrogenic undescended testes may be unrecognized cryptorchid testes at herniorrhaphy we examined biopsies of iatrogenic undescended testes and the corresponding contralateral descended testis. MATERIALS AND METHODS: Between 1985 and 1999 bilateral testis biopsies were obtained at orchiopexy in 37 boys 1.5 to 11.8 years old who previously underwent inguinal hernia correction. Histomorphometric analysis of germ cell counts was performed on the undescended and contralateral descended testes, and compared to the count in bilateral biopsies of 37 age and position matched patients with true unilateral cryptorchidism. RESULTS: There were no significant differences in volume or total and differential germ cell counts in the undescended and contralateral descended testes in the study groups and age matched controls with primary unilateral cryptorchidism. The mean number of germ cells per tubule in the undescended testis in patients with a greater than 5-year interval from herniorrhaphy to orchiopexy was significantly decreased compared to those with an operative interval of less than 5 years (0.27 +/- 0.33 versus 0.93 +/- 1.4, p = 0.026). CONCLUSIONS: Some patients with iatrogenic undescended testis may have an unrecognized low cryptorchid testis. Careful physical examination before and after inguinal surgery is recommended. The early repair of iatrogenic undescended testis is warranted to prevent further damage.

Child↗
PubMed2001

The use of vesicostomy as permanent urinary diversion in the child with myelomeningocele.

PURPOSE: Treatment of the child with myelomeningocele presents the urologist with many challenges. While vesicostomies are usually used for temporary bladder drainage until continent reconstruction is performed, we have a population of postpubertal patients with myelomeningocele in whom vesicostomies have been preserved. We review our experience with these older children. MATERIALS AND METHODS: A search of our database of 350 patients with myelodysplasia identified 23 with urinary diversion accomplished by permanent vesicostomy. Those who had undergone vesicostomy after age 11 years were designated as group 1. Those who received a vesicostomy early in life that was maintained post puberty were designated as group 2. Indications for vesicostomy, upper tract status before and after vesicostomy, recurrent infections and complications were noted. Upper tract status was determined by serial ultrasounds during routine followup. RESULTS: Group 1 was comprised of 5 patients with mean age at vesicostomy of 17 years and a mean followup interval of 5.2 years. Group 2 was comprised of 18 patients with mean age of vesicostomy at 2.6 years and mean followup interval of 13 years. Hydronephrosis resolved in all children from both groups. Vesicostomy revision was required in 1 patient secondary to prolapse. Other complications included mild prolapse that did not require revision, stenosis requiring revision 5 months after the initial procedure and an early bilateral ureterovesical obstruction that resolved. Of the patients 33% had recurrent upper tract calculi. CONCLUSIONS: While the goal of achieving urinary continence is well worth striving for in the child with myelomeningocele, it is not realistic for all patients. We believe that permanent cutaneous vesicostomy is an acceptable alternative that the reconstructive surgeon should consider. This reliable and simple technique ensures safe decompression of the upper urinary tracts, while avoiding the complications of urinary diversion using segments of bowel.

Adolescent↗
PubMed2000

Ectopic and undescended testes: 2 variants of a single congenital anomaly?

PURPOSE: We compared pathological findings in ectopic and undescended testis to determine whether the pathological evidence supports the hypothesis that the 2 conditions are variants of the same congenital anomaly. MATERIALS AND METHODS: We identified 24 boys with ectopic testis not in the superficial inguinal pouch of Denis Browne. Seven boys were excluded from study due to unavailable clinical records for 3, contralateral undescended testis in 2 and inadequate biopsy specimens in 2. Pathological findings of ectopic testis in the remaining 17 patients were compared with those of age matched patients with unilateral undescended testis. Total germ cell count, testicular volume, patency of the processus vaginalis and epididymal abnormalities were compared. Data were analyzed using the Wilcoxon matched pairs signed rank and Fisher's exact tests. RESULTS: No difference was noted in total germ cell count (p = 0.33), testicular volume (p = 0.1475), processus vaginalis patency (p = 0.0854) or epididymal abnormalities (p = 1.00) in the 2 groups. Of the 24 boys (8%) with ectopic testis 2 also had a contralateral undescended testis. CONCLUSIONS: Similar pathological findings in ectopic and undescended testes as well as the association of ectopic testis with a contralateral undescended testis suggest that ectopic and undescended testes are variants of the same congenital anomaly. Thus, boys with ectopic testis may have an increased incidence of subfertility and testicular malignancy. This spectrum of abnormal testicular position, and its range of pathological conditions and complications may appropriately be called the undescended testis sequence.

Abdomen↗
PubMed2000

The decompensated detrusor III: impact of bladder outlet obstruction on sarcoplasmic endoplasmic reticulum protein and gene expression.

PURPOSE: Regulation of calcium ion homeostasis has a significant role in smooth muscle contractility. The sarcoplasmic endoplasmic reticulum, calcium, magnesium, adenosine triphosphatase (SERCA) is a regulatory ion pump that may have a role in the functional outcome after outlet obstruction. We investigate what correlation if any existed between SERCA protein and gene expression, and the contractile properties in the same bladder. MATERIALS AND METHODS: Standardized partial bladder outlet obstructions were created in adult New Zealand white rabbits, which were divided into control, sham operated and obstructed groups. Muscle strip studies subcategorized the obstructed group into compensated (force greater than 50% of control) and decompensated (force less than 50% of control). Microsomal membrane and total RNA fractions were prepared from the same bladder tissue. Membrane proteins were used for Western blot analysis using a SERCA specific monoclonal antibody, and total RNA was assessed with Northern blot analysis. RESULTS: The relative intensities of signals for the Western and Northern blots demonstrated a strong correlation between protein and gene expression. Furthermore there was a strong association between the loss of SERCA messenger RNA and protein expression and loss of bladder function. CONCLUSIONS: Bladder contractility after outlet obstruction is influenced in part by smooth muscle cell ability to maintain calcium homeostasis via SERCA. The loss of SERCA protein expression is mediated by down-regulation in gene expression in the same bladder. These data suggest that smooth muscle ion pump gene expression is in part mechanically (pressure work) regulated.

Animals↗
PubMed2000

The role of renal salvage procedures for bilateral Wilms tumor: a 15-year review.

PURPOSE: We reviewed our experience with renal salvage procedures in patients with bilateral Wilms tumor to determine the clinical outcome. MATERIALS AND METHODS: From 1982 to 1997, 23 children with bilateral Wilms tumor were treated with partial nephrectomy at our institution, including 7 who were also treated with brachytherapy. Medical history, use and response to chemotherapy and brachytherapy, operative records, renal function, pathological results, survival, and techniques for partial and repeat nephrectomy and brachytherapy were reviewed. RESULTS: We treated 8 boys and 15 girls, of whom 21 who presented with synchronous bilateral Wilms tumor underwent primary chemotherapy followed by secondary partial nephrectomy. A total of 44 partial nephrectomies were performed and brachytherapy was done in 7 patients. Ten children have normal renal function and no disease, 10 are dead and 2 have metastatic disease. Anaplasia was the most significant factor associated with an unfavorable outcome (p = 0.003). Of the patients who were cured 60% had a positive response to initial chemotherapy compared with only 25% who had an unfavorable outcome (p = 0.09). No significant differences were noted with respect to gender, age at presentation, highest local tumor stage at presentation or initial nephrectomy. No patient treated with brachytherapy had local recurrence. CONCLUSIONS: Preoperative chemotherapy followed by nephron sparing surgery is indicated in patients with bilateral Wilms tumor, while in those with diffuse anaplasia nephron sparing surgery is contraindicated. Brachytherapy should be considered for treating local disease involving chemoresistant tumors.

Brachytherapy↗