Biomedical subjects
Publications and source records attributed to Hsi-Yang Wu.
Urethral atresia is a rare and usually fatal cause of prenatal bladder outlet obstruction. We present a case of urethral atresia with urinary ascites to highlight the difficulties in making the diagnosis in the absence of hydronephrosis. We also discuss possible reasons why this patient maintained normal renal and pulmonary function.
PURPOSE OF REVIEW: The management of Wilms' tumor continues to evolve with two different approaches being taken by the National Wilms Tumor Study in North America and the International Society of Pediatric Oncology in Europe in regards to preoperative chemotherapy. Limiting the duration, dosage, and number of chemotherapeutic agents and the dosage of radiotherapy are common goals in both trials. RECENT FINDINGS: Contralateral exploration of unilateral tumors will no longer be recommended in future National Wilms Tumor Studies. Percutaneous biopsy for tissue diagnosis is quite accurate, but there are concerning complications with its use. Partial nephrectomy is successful for low risk unilateral Wilms tumor, but its indications remain controversial. The surgical complication rate was similar between the National Wilms Tumor Study and the International Society of Pediatric Oncology, but intraoperative tumor spill was higher in the North American trials. Doxorubicin decreased the risk of recurrence in stage III tumors by 50%, and its current dose is not associated with late congestive heart failure. For selected patients, shorter courses of vincristine/dactinomycin or vincristine alone show equivalent results compared to current regimens. A longer course of chemotherapy (including doxorubicin) for clear cell sarcoma improves recurrence-free survival. Patients with Wilms' tumor, aniridia, major genitourinary malformations, and mental retardation, the WAGR syndrome, have a 50% chance of unexplained end-stage renal disease 20 years after treatment. SUMMARY: Less aggressive means of diagnosis and treatment for Wilms' tumor are continuing to achieve very good cure rates while lowering long term morbidity for low risk patients. High-risk patients with unfavorable histology or the WAGR syndrome benefit from more intensive treatment and long-term follow-up.
The management of urolithiasis in children poses specific technical challenges that require planning before endoscopy and that affect the risks and outcomes of these procedures. The indications for operative intervention in children and adults are similar:infection, persistent symptoms of flank pain, nausea, and vomiting, as well as the failure to pass a ureteral stone after an appropriate trial of observation (3-6 weeks). Specific adjustments for performing extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and cystolithotomy in children are discussed.
Although treatment for bladder, prostate, and testis cancer comprises a large part of adult urologic practice, the tumors that affect these organs in children are rare. Rhabdomyosarcoma,which affects the bladder, prostate, vaginal, and paratesticular areas,is treated with a combination of surgery, chemotherapy, and radiation. Most transitional cell carcinomas of the bladder and prepubertal testis tumors are managed surgically owing to the low stage at presentation. Application of the technical advances learned in adults with tumors of the bladder, prostate, and testis, combined with an understanding of the difference in tumor biology, helps urologists improve the treatment of these tumors in children.
PURPOSE: A change in calcium handling has been proposed as the cause of decreased maximal force generation by neonatal bladders with growth. Recent studies suggest that increased myosin heavy chain isoform SM1 increases force generation. We studied force generation in neonatal mouse bladders to determine if decreases in SM1 corresponded with decreased force. MATERIALS AND METHODS: C57Bl/6 mice were studied from birth to 12 weeks of life (adulthood). The bladder strip contractile response to KCl and bethanechol was followed by the inhibition of rho-kinase activity by Y-27632. The mRNA levels for SM1/SM2 were determined using reverse transcriptase-polymerase chain reaction and protein levels were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Muscle fraction per cross-sectional area was determined by trichrome staining. RESULTS: Newborn bladders generated significantly more tension in response to KCl (43.3 vs 17.4 mN/mm2, p = 0.02) and bethanechol (40.6 vs 11.9 mN/mm2, p = 0.05) than adult bladders. Inhibition of rho-kinase resulted in similar decreases in tension in all bladders. SM1 mRNA decreased slightly from 60% at birth to 50% at 12 weeks. SM1 protein decreased from 72.5% at birth to 50% by 3 weeks and it remained stable at 12 weeks. Total myosin per gm protein remained stable. Muscle fraction decreased from 63.8% at birth to 58.6% at 12 weeks (p = 0.4). CONCLUSIONS: We noted a decrease in SM1 that corresponded to a decrease in bladder force generation. The concept that SM1 contributes to the optimal assembly of myosin filaments suggests that changes in myosin isoforms may have a role in the decrease in voiding pressures seen in normal children.
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PURPOSE: We studied the ability of testis biopsy to predict eventual fertility potential. MATERIALS AND METHODS: A total of 25 patients with unilateral undescended testis and 11 with bilateral undescended testes who previously underwent orchiopexy at a median age of 9 years were followed until after age 18 years. Semen analysis, testicular volume, follicle-stimulating hormone, luteinizing hormone, testosterone and inhibin B were compared to previously obtained biopsies of each testis. Biopsies were graded as mild, moderate or severe histology based on published data for normal and undescended testis histology. RESULTS: Patients with unilateral undescended testis and moderate histology were more likely to have a sperm density of greater than 20 million per cc than those with severe histology (p = 0.006), although no difference in hormonal parameters was noted. Patients with bilateral undescended testes and moderate histology were more likely to have normal follicle-stimulating hormone and inhibin B than those with severe histology (p = 0.05 and 0.002, respectively), although no difference in semen analysis was observed. Overall 7 of the 9 patients with bilateral undescended testes had less than 20 million sperm per cc. CONCLUSIONS: Testis biopsy provides useful prognostic information about semen analysis in patients with unilateral undescended testis. In the 9 patients with bilateral undescended testes testis biopsy divided them into normal and abnormal groups in terms of hormonal parameters. Testis biopsy was not able to provide additional prognostic information on semen analysis in patients with bilateral undescended testes since they were uniformly poor.
PURPOSE: We reviewed our experience with genitourinary malformations associated with chromosome 22q11.2 deletion. MATERIALS AND METHODS: We retrospectively reviewed patient intake charts at the 22q clinic at our institution. We assessed 73 renal/bladder ultrasounds and 7 autopsies performed between 1998 and 2000 for renal and bladder malformations. A total of 149 male patients were evaluated for possible testicular and urethral malformations. RESULTS: Of 80 patients 25 (31%) had a structural urinary tract anomaly. Another 8 patients had renal agenesis or multicystic dysplastic kidney, 4 had hydronephrosis and 5 had vesicoureteral reflux or an irregular bladder, while 8 of 73 (11%) had dysfunctional voiding, 9 of 149 (6%) had undescended testes and 12 of 149 (8%) had hypospadias. CONCLUSIONS: Screening renal/bladder ultrasound, careful voiding history and medical but not surgical therapy are recommended for renal and bladder anomalies associated with 22q11.2 deletion. The need for surgery for cryptorchidism and hypospadias is slightly higher than in the general population.
PURPOSE: The etiology of the ascending testis is controversial. We propose that ascending testis, defined as a testis previously thought to be descended and later noted to be out of the scrotum, is due to mild hypogonadotropic hypogonadism affecting both testes. The diagnosis of these low types of true undescended testes is difficult to make clinically in children since they are frequently confused with retractile testes. In this study we compared testicular biopsies in a group of boys with ascending testes with those in boys who had an undescended testis since birth (primary undescended testis). MATERIALS AND METHODS: Between 1985 and 1995, 91 patients with ascending testes underwent orchiopexy and bilateral testis biopsy. The total germ cell count, processus vaginalis status, age at surgery and whether followup was done by a pediatrician or pediatric urologist were compared in patients with ascending and unilateral primary undescended testes. RESULTS: The total germ cell count was similar in the undescended and the contralateral descended testis in patients with ascending and primary undescended testes. The processus vaginalis was more likely to be closed in ascending testes (57% versus 36%, p = 0.0001). Age at surgery and the total germ cell count were similar in patients followed by pediatricians and pediatric urologists. CONCLUSIONS: The ascending testis has the same germ cell count as the primary undescended testis. Yearly followup by the primary care physician is recommended for patients with retractile testes.
PURPOSE: The spontaneous resolution rate of vesicoureteral reflux is helpful for determining the need for surgical intervention and the proper followup schedule in patients on antibiotic prophylaxis. We determined the resolution rate by patient rather than by ureter and analyzed the effects of laterality, gender, age and dysfunctional voiding. MATERIALS AND METHODS: We retrospectively reviewed the records of 179 girls and 35 boys who presented between 1981 and 1984 with urinary tract infection and were diagnosed with primary vesicoureteral reflux. Mean age at presentation was 4.2 years and median followup was 3 years. Of the patients 107 (50%) had bilateral reflux and 60 had dysfunctional voiding. In 146 children (68%) reflux spontaneously resolved during the study. Patients were categorized by the worst grade of reflux, maintained on antibiotic prophylaxis and underwent voiding cystourethrography yearly until reflux resolved. Kaplan-Meier curves were constructed to define the resolution rate. RESULTS: Grades I to III reflux resolved at 13% yearly during the initial 5 years of followup and then at 3.5% yearly during subsequent followup. Grade IV to V reflux resolved at 5% rate yearly. Bilateral reflux resolved more slowly than unilateral reflux and it resolved more rapidly in boys than in girls. Untreated dysfunctional voiding had no effect on overall resolution. CONCLUSIONS: Grades I to III primary vesicoureteral reflux diagnosed after urinary tract infection resolve at identical rates and significantly more rapidly than grades IV to V. Early repair of grade IV to V reflux should be considered after age 18 months.