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Biomedical subjects

P A Dewan

Publications and source records attributed to P A Dewan.

At least 19 recordsLinked to original sources
PubMed1999

Ureteric tunnel incision in the fetal pig: a model for non-obstructive prenatal vesicoureteric reflux.

The understanding of vesicoureteric reflux (VUR) continues to improve, particularly as the renal tract can now be assessed prenatally. To further study the evolution of fetal renal changes, we studied two neonatal piglets that had undergone midgestation ureteric tunnel ablation. Dilatation of the pelvicalyceal system was seen radiologically and macroscopically in all three kidneys into which VUR had been created. Despite the study being marred by poor fetal survival, the results indicate that the model should be developed further to explore what appears to be an interrelationship between VUR and renal parenchymal changes in utero.

Animals↗
PubMed1999

Ureterocystoplasty in a patient with a single kidney.

Ureterocystoplasty (UCP) has now been widely used for bladder augmentation, with and without unilateral nephrectomy. Many techniques have been described to incorporate portions of the upper renal tract, but none have yet described UCP in a child with unilateral renal agenesis.

Child↗
PubMed1999

Extraperitoneal ureterocystoplasty with transureteroureterostomy.

Ureterocystoplasty enables the bladder to be reliably enlarged and the resultant neobladder to be lined by urothelium. Many techniques have been described for the operative management of the lower ureter, and a number of alternatives have been suggested for reconstruction of the upper renal tract and bladder. This report describes a new approach that allows renal preservation, transureteroureterostomy, and ureterocystoplasty through an extraperitoneal approach.

Child, Preschool↗
PubMed1999

Plastic migration from implanted central venous access devices.

BACKGROUND: This is the first reported study of histologically confirmed migration from intravenous access devices in children. METHODS: The capsules from around intravenous access devices were examined by light microscopy to determine the extent of the foreign body response; energy dispersive x ray analysis was performed to document the elemental content of the foreign material. RESULTS: A fibroconnective tissue capsule was found around all the samples. Elemental silicon was found in six of 13 tissue samples, and a foreign body giant cell reaction was seen in three of these. CONCLUSIONS: The pseudocapsule that surrounds an implanted vascular access device often has residual foreign material, including silicone.

Catheterization, Central Venous↗
PubMed1999

Vesicoureteric reflux: the evolution of the understanding of the anatomy and the development of radiology.

Vesicoureteric reflux is now recognized to be a disease which is different in boys and girls and known to be associated with renal parenchymal abnormalities in the fetus. Understanding the anatomy and reviewing the development of the radiologic investigation of vesicoureteric reflux helps put in context conclusions reached from recent clinical and laboratory studies, on which new insights into vesicoureteric reflux have been based.

Animals↗
PubMed1998

Autoaugmentation demucosalized enterocystoplasty.

Autoaugmentation demucosalized enterocystoplasty has been developed from the combination of the autoaugmentation technique, the use of the stomach and colon for bladder augmentation and the ability of the bowel and stomach to survive the removal of their epithelial lining. The initial combined approach used the stomach as the source of muscle, with the colon subsequently being used as an alternative. The operations have been applied in the laboratory and clinically, giving good results for bladder augmentation with both sources of enteric muscle, more reliably so and with a greater ease of separation of the mucosa when stomach muscle is used. There is hope that further research will improve the outcome of what is a technically challenging procedure.

Animals↗
PubMed1998

Upper pole pelviureteric junction obstruction.

A case of neonatal hydronephrosis affecting the upper moiety of a duplex kidney is presented. In addition to the ectopic insertion of the upper-pole ureter into the urethra, the ureter was obstructed by the lower pole at its pelviureteric junction.

Female↗
PubMed1998

Venous access via the renal vein: a technical innovation.

A patient with difficult venous access is described in whom both haemodialysis and parenteral nutrition were required. To minimize the impact on transplant prospects, the renal veins were used for vascular access. The technique and rationale for this novel approach are presented.

Catheters, Indwelling↗
PubMed1998

The relationship of age to pathology in pelviureteric junction obstruction.

OBJECTIVE: To ascertain the age distribution of the different pathological mechanisms which lead to the development of pelviureteric junction obstruction. METHODS: A series of 165 kidneys in 158 children who underwent pyeloplasty for pelviureteric junction obstruction were reviewed. Those 132 renal units (127 children) with uncomplicated pathology were selected for further study. The operative records were reviewed for the underlying cause of obstruction and the age at operation. RESULTS: Obstruction due to extrinsic compression by an aberrant lower pole vessel occurred in an older group (median age 67.3 mo) than those with a narrowing or angulation of the pelviureteric junction (median age 3.1 mo). CONCLUSIONS: Pelviureteric junction obstruction, secondary to a lower pole vessel presents at an older age. Doppler ultrasonography to detect a lower pole vessel may be of benefit in the management of equivocal cases of pelviureteric junction obstruction, particularly in prenatally diagnosed hydronephrosis.

Adolescent↗
PubMed1997

Further observations on histological changes at the ureteroileal junction in ileal conduits.

Seventy-two ureteroileal anastomoses taken from ileal conduits removed from 62 patients were examined histologically to characterize the range of mucosal and stromal changes at these sites. All 72 demonstrated variable amounts of subepithelial chronic inflammation and fibrosis. Other histological features included: cystic spaces lined by transitional epithelium (N = 29; 40%; average diameter 1.2 mm); cystic spaces lined by mixed intestinal/transitional epithelium (N = 5; 7%; average diameter 0.77 mm); and cystically dilated intestinal glands (N = 21; 29%; average diameter 0.24 mm). The latter were associated with overgrowth by transitional epithelium, which had prevented mucus drainage. Twenty-one (29%) had mucus pools with no epithelial lining (average diameter 1.2 mm), and polypoidal protrusions into the lumen of the anastomosis were found containing mucus pools (N = 4; 6%; average diameter 1.4 mm), transitional-lined cysts (N = 5; 7%; average diameter 2.2 mm), and mixed intestinal/transitional-lined cysts (N = 2; 3%; average diameter 2.5 mm). Focal rupture of dilated intestinal glands with interstitial pooling of mucus was not uncommon, and marked dystrophic calcification was found in 1 case within a large collection of extracellular mucus. This series confirms that inflammation, fibrosis, and glandular overgrowth by transitional epithelium are common occurrences at ureteroileal anastomosis sites. Subsequent gland rupture may result in sizable accumulations of interstitial mucus, and rarely in marked dystrophic calcification.

Adolescent↗
PubMed1997

An in vitro study of silicone migration from intravenous fluid tubing.

Migration of particulate matter from plastic tubing and solid plastic implants has been documented in a number of studies, including some with the use of cardiac bypass, haemodialysis, and pump-assisted intravenous infusions. In order to ascertain whether silicone embolisation occurs when children have an Ivac 560 pump-assisted IV infusion, we passed 180 ml of pumped fluid through a microfilter and compared the scanning electron micrographs of those filters with unused filters and with others through which a similar volume had been passed without using the pump. The particles on the filters were analysed for their elemental content using energy-dispersive X-ray analysis. In addition, the appearance of the silicone tubing used in the pump over 3 and 72 h was assessed and compared to that of flow-only and unused tubing. More particles were found on the microfilter when fluid had been delivered via the pump than on those through which non-pumped fluid had passed or that were unused. Elemental silicon-containing particles were only found on the filter when a pump had been attached to the IV line. The flow-only and unused tubing were found to have adherent particles on the inner surface that were not seen once the tubing had been used for 3 h in the Ivac 560 pump. Also, after 72 h use, the silicone tubing had a deformed inner layer. The clinical significance of these findings is yet to be determined, but it does appear that silicone embolisation occurs during pump-assisted infusions in children.

Biocompatible Materials↗
PubMed1997

Correlation of the endoscopic and radiological anatomy of congenital obstruction of the posterior urethra and the external sphincter.

OBJECTIVE: To determine whether the external sphincter is distal to congenital occlusion of the posterior urethra in boys by correlating endoscopic video-recorded information with cysto-urethrographic observations and assessing the anatomy of the disease. PATIENTS AND METHODS: This study reviewed the endoscopic and radiographic findings in 42 boys (mean age 42 months, range newborn to 14 years), using material from a videotape library, and correlated these with the pre-operative cystogram. The nature of the obstructive lesion and its relationship to the verumontanum and the external sphincter was assessed. RESULTS: Of the 42 boys, 36 had the proximal extent of the external sphincter identified on the endoscopic video recording to be above the posterior urethral membrane; 22 of the membranes were obstructive. The proximal extent of the external sphincter was identified on the static cystogram images of only 31 of the 38 boys examined, but only ever above the posterior urethral membrane. CONCLUSION: The proximal extent of the external sphincter, i.e. that portion which is most prominent endoscopically, is proximal to the membrane in congenital obstruction of the posterior urethra.

Adolescent↗
PubMed1997

Enteric mucosal regrowth after bladder augmentation using demucosalized gut segments.

PURPOSE: Regrowth of the enteric mucosa on a denuded muscular flap enterocystoplasty is an undesirable complication of demucosalized enterocystoplasty. This study was performed to understand how regrowth can be prevented and, thus, a complete urothelial lined enterocystoplasty can be achieved. MATERIALS AND METHODS: We performed bladder augmentation on 30 sheep using demucosalized seromuscular gastric or colonic flaps with or without autoaugmentation. The epithelium and muscularis mucosae were completely removed from the gastric flap. Initial attempts to remove the muscularis mucosae and most of the submucosal layer from the colonic flap by cautery caused bleeding and muscle damage. Thus, demuscosalization was done by stripping with forceps, in which the muscularis mucosae and submucosa remained largely intact on the colonic flap. Sheep were sacrificed 4 to 12 months postoperatively and bladders were inspected for mucosal regrowth. Subsequently autoaugmentation with demucosalized seromuscular gastric or colonic flaps was performed clinically in 10 children in whom the enteric epithelium and muscularis mucosae were removed completely with part of the submucosa by dissection through the submucosal plane. These children were followed with urodynamic studies and mucin staining of urine up to 39 months postoperatively. RESULTS: Regrowth of islands of enteric mucosa occurred in 4 of the 5 animals in which the muscularis mucosae and submucosal layers were preserved on a colonic flap. In all animals with mucosal regrowth the bowel was prepared by stripping the mucosa. Mucosal regrowth did not occur in any animal after complete removal of the muscularis mucosae and the inner portion of the submucosa from the stomach or colon. All patients had satisfactory urodynamic results and no evidence of enteric mucosal regrowth. CONCLUSIONS: Removal of the muscularis mucosae with the inner portion of the submucosa appears necessary to prevent enteric mucosal regrowth on the muscular flap of a demucosalized enterocystoplasty. In addition, this level of dissection does not seem to interfere with the success of bladder augmentation in children.

Animals↗
PubMed1997

Congenital posterior urethral obstruction: the historical perspective.

The currently accepted interpretation of urethral anatomy and pathology in boys is based on studies from the first half of this century, most notably from Hugh Hampton Young and his colleagues. The studies that led to Young's conclusions and the developments in the management allow for reinterpretation, particularly with the advent of prenatal diagnosis and video-endoscopic recording technology.

Europe↗