Hwang Choi

A fractional four-step finite element formulation of the unsteady incompressible Navier-Stokes equations using SUPG and linear equal-order element methods

A numerical algorithm using equal-order linear finite element and fractional four-step methods is presented for the analyses of incompressible fluid flow and heat transfer problems. The SUPG (streamline upwind Petrov-Galerkin) method is used for the weighted formulation of the Navier-Stokes equations. With the fractional four-step method, the memory and cost requirements of computations are significantly reduced because the pressure is split from the momentum equation. The pressure equation is derived from the mass conservation without any approximation procedure, such as adopted in the previously developed SIMPLE algorithm based finite element method. Therefore, the present numerical algorithm gives more accurate results than it does. Furthermore, the newly proposed pressure equation successfully treats the outflow boundary condition. The present algorithm has been applied to the well-known bench mark problems and proves to be efficient and accurate.

Laparoendoscopic Single-Site Nephrectomy Using a Homemade Single-Port Device for Single-System Ectopic Ureter in a Child: Initial Case Report

A 3-year-old girl with a history of continuous urinary incontinence was found to have a right single-system ectopic ureter. She underwent laparoendoscopic single-site nephrectomy without any intraoperative or postoperative complications. To the best of our knowledge, this is the first case report of a laparoendoscopic single-site nephrectomy for single-system ectopic ureter in a child.

Augmentation of cisplatin sensitivity in cisplatin-resistant human bladder cancer cells by modulating glutathione concentrations and glutathione-related enzyme activities

To investigate the roles of glutathione and glutathione‐S‐transferase (GST) in cisplatin‐resistance mechanisms in human bladder cancer, by using glutathione‐depleting or GST‐blocking agents.

Combined effect of glutathione S-transferase M1 and T1 genotypes on bladder cancer risk

To evaluate the association between genetic polymorphism of GSTM1, GSTT1 and development of bladder cancer, a hospital-based case-control study was conducted in South Korea. The study population consisted of 232 histologically confirmed male bladder cancer cases and 165 male controls enrolled from urology departments with no previous history of cancer or systemic diseases in Seoul during 1997-1999. The GSTM1 null genotype was significantly associated with bladder cancer (OR: 1.6, 95% CI: 1.0-2.4), whereas the association observed for GSTT1 null genotype did not reach statistical significance (OR: 1.3, 95% CI: 0.9-2.0). There was a statistically significant multiple interaction between GSTM1 and GSTT1 genotype for risk of bladder cancer (P=0.04); the risk associated with the concurrent lack of both of the genes (OR: 2.2, 95% CI: 1.2-4.3) was greater than the product of risk in men with GSTM1 null/GSTT1 present (OR: 1.3, 95% CI: 0.7-2.5) or GSTM1 present/GSTT1 null (OR: 1.1, 95% CI: 0.6-2.2) genotype combinations.

Laparoscopy for Definite Localization and Simultaneous Treatment of Ectopic Ureter Draining a Dysplastic Kidney in Children

BACKGROUND AND PURPOSEnSingle-system ectopic ureter draining a dysplastic kidney is a rare urologic abnormality. In this study, we evaluated our own experience using laparoscopy for the simultaneous identification and removal of such ureterorenal units.nnnPATIENTS AND METHODSnBetween February 1999 and August 2001, four girls with a mean age of 11 years presented with urinary incontinence. After imaging studies including CT scan, MRI, or both were done, all the patients underwent laparoscopy for definitive localization and simultaneous treatment.nnnRESULTSnIn all cases, ultrasonography and intravenous urography combined to reveal a single normal kidney. Even the CT scan could not identify the dysplastic kidney or ectopic ureter in three children. Laparoscopy was performed transperitoneally in all four patients, and a small dysplastic kidney was identified. Discovery of the kidney was not difficult because we initially identified the ureter crossing over the iliac vessels. Laparoscopic nephroureterectomy was successful in all patients with a mean operative time of 102 minutes. There was no significant intraoperative or postoperative complication, and the mean postoperative hospital stay was 2.5 days. All patients have remained completely dry without any problems after surgery.nnnCONCLUSIONSnFor patients having a clinical suspicion of ectopic ureter draining a dysplastic kidney, laparoscopy may represent an alternative modality for simultaneous diagnosis and treatment.

Knowledge and attitudes of Korean parents towards their son's circumcision: a nationwide questionnaire study

Objective To evaluate knowledge about the foreskin and circumcision, and to understand the attitudes of parents to circumcision in Korea, where circumcision in childhood is widely practised with no particular religious or medical background.

Long-term Outcomes of Dismembered Pyeloplasty for Midline-crossing Giant Hydronephrosis Caused by Ureteropelvic Junction Obstruction in Children

OBJECTIVESnTo assess the long-term surgical outcomes of dismembered pyeloplasty for congenital midline-crossing giant hydronephrosis (GH) caused by ureteropelvic junction obstruction (UPJO).nnnMETHODSnFrom June 1986 to September 2005, 167 unilateral UPJO pediatric patients who underwent dismembered pyeloplasty performed by a single surgeon were retrospectively analyzed. The patients were followed up for more than 5 years. Differential renal function (DRF) assessed by DTPA renal scan more than 3 years postoperatively was compared between GH and non-GH children. Improvement in renal parenchymal thickness (RPT) on ultrasonography at 5 years postsurgery was also compared. In GH children, surgical outcomes were compared based on the age at operation and whether preoperative nephrostomy was performed.nnnRESULTSnDRF measured more than 3 years postoperatively was 33 ± 14% versus 48 ± 12% (P < .05), and the improvement of RPT was 4 ± 2 mm (181%) versus 5 ± 4 mm (168%) in GH (n = 25) and non-GH (n = 142) children, respectively (P = .305). GH patients who underwent pyeloplasty before 12 months of age (n = 13) experienced more improvement in RPT (192% vs 102%) compared with GH patients who underwent surgery after 12 months of age (n = 12) (P < .05). The surgical outcomes for RPT improvement or long-term DRF were not different based on whether preoperative nephrostomy was performed. No children developed hypertension or elevated serum creatinine.nnnCONCLUSIONSnLong-term surgical outcomes after dismembered pyeloplasty for GH were satisfactory. In children with GH caused by UPJO, early relief of obstruction allows comparable nephron sparing.

Effect of glycine on recovery of bladder smooth muscle contractility after acute urinary retention in rats

To investigate the effects of glycine on the recovery of bladder smooth muscle contractility after acute urinary retention.

EFFECTS OF LOCAL ANESTHETICS ON THE CONTRACTILITY OF RAT BLADDERS

PURPOSEnWe investigated the effect of local anesthetic agents on the detrusor muscle in rats.nnnMATERIALS AND METHODSnIn vitro isometric contraction of rat detrusor strips was measured. We investigated the effects of tetracaine, bupivacaine and lidocaine on baseline spontaneous contractions and contractions induced by various stimuli, including 60 mM. KCl, carbachol and electricalal field stimulation with a pulse duration of 0.8 or 100 milliseconds.nnnRESULTSnLocal anesthetic agents have complex effects on baseline spontaneous contractility that depend on the type of agent used and its concentration. These agents inhibited nerve mediated contraction resulting from electricalal field stimulation with a pulse duration of 0.8 milliseconds in a concentration dependent manner and also inhibited nonnerve mediated detrusor contractions induced by KCl, carbachol or electricalal field stimulation with a pulse duration of 100 milliseconds Higher concentrations of local anesthetic agents were needed to inhibit nonnerve than nerve mediated contractions. In rat detrusor muscle carbachol induced a sustained tonic contraction even after the depletion of internal and external Ca2+ sources, which was also inhibited by local anesthetic agents.nnnCONCLUSIONSnThese results show that local anesthetic agents have a wide spectrum of inhibitory effects on the contraction of bladder smooth muscle induced by various stimulants at different concentrations, which may be potentially useful for treating overactive bladder.

NO FURTHER DEVELOPMENT OF RENAL SCARRING AFTER ANTIREFLUX SURGERY IN CHILDREN WITH PRIMARY VESICOURETERAL REFLUX: REVIEW OF THE RESULTS OF99m TECHNETIUM DIMERCAPTO-SUCCINIC ACID RENAL SCAN

PURPOSEnReports of previous studies using excretory urography indicate that significant numbers of new scars developed in 5 to 31% of cases and scarring progressed in 11 to 16% after antireflux surgery. We evaluated renal scarring after surgery using a more accurate method, that is dimercapto-succinic acid renal scintigraphy.nnnMATERIALS AND METHODSnBetween 1985 and 1997 antireflux surgery was performed for primary vesicoureteral reflux in 223 children at our hospital. Of these patients 45 boys and 29 girls with a median age of 74 months at surgery in whom preoperative and postoperative renal scans were available form the basis of our retrospective study. Renal scan was performed 0.3 to 58 months (median 2) preoperatively and 5.3 to 44 months (median 18.7) postoperatively. A total of 24 children (39 renal units) were followed further by additional scanning for as long as 25 to 120 months (median 43.2) postoperatively. Each scan was blindly reviewed for the size, number and zone location of cortical defects based on morphology. Interval changes were grouped into categories as improved, no change, progressed and new scar formation.nnnRESULTSnPostoperatively there was no ureteral obstruction. Pyelonephritis developed in 2 patients (2.7%) and asymptomatic bacteriuria was noted in 35 (47.3%) postoperatively. Of the renal units 110 (86.6%) showed no change, while 15 (11.8%) were improved and 2 (1.6%) had progression. In no case was new renal scar formation observed.nnnCONCLUSIONSnContrary to most previous reports involving excretory urography, our results indicate no significant progression of renal scarring after antireflux surgery. In most cases postoperative followup renal scans demonstrated no significant morphological change. When there was change, it mostly involved the disappearance or decrease of renal scars.