Ureteral structure and ultrastructure. Part V. The dysplastic ureter

Positive outcomes of phosphodiesterase type 5 inhibitor on histopathologic and biochemical changes induced by ureteral obstruction

OBJECTIVES

We examined the effects of tadalafil, one of the phosphodiesterase type 5 (PDE5) inhibitors, in a rat model of with partial and complete unilateral ureteral obstruction (UUO).

METHODS

The rats were divided into 5 groups: sham (n=6), partial unilateral ureteral obstruction (PUUO, n=6), PUUO with tadalafil treatment (PUUO+T; Cialis, 10 mg/72 h, intragastric; Lilly, Indianapolis, Indiana, USA), complete unilateral ureteral obstruction (CUUO, n=6), and CUUO with tadalafil treatment (CUUO+T).

RESULTS

Fifteen days after the UUO, the ureter presented changes in the layers of urothelium and significant infiltration of inflammatory cells in the PUUO and CUUO groups. Compared with the sham, PUUO and CUUO groups had severe increased inflammatory cell infiltration. The urothelial epithelium exhibited cell degeneration and loss because of the swollen, atrophic, and denuded epithelial cells in the PUUO and CUUO groups. In the PUUO+T and CUUO+T groups, the urothelium revealed less epithelial cell degeneration and loss.The expressions of α-smooth muscle actin (α-SMA) and transforming growth factor-β (TGF-β) exhibited up-regulation in the PUUO and CUUO groups. The expression of TGF-β decreased positively correlated with that of α-SMA in the tadalafil therapy groups, PUUO+T and CUUO+T.

CONCLUSION

The phosphodiesterase type 5 inhibitor's tadalafil reduced expressions of α-SMA and TGF-β in the obstructed ureters, measured by biochemical examinations. In addition, tadalafil decreased urothelium degeneration due to the decreased epithelial cell loss and inflammatory cell infiltration. Our results show that tadalafil prevents or slows down the onset of ureter inflammation and urothelial degeneration in rats with UUO.

A quantitative histological evaluation of the dilated ureter of childhood. II: Ectopia, posterior urethral valves and the prune belly syndrome

A quantitative histological study was performed on specimens of 33 ureters obtained from 14 male and 19 female patients 5 days to 14 years old (mean age 1.2 years). A high resolution color image video analysis system was used to quantify and compare collagen and smooth muscle components of the muscularis layers to normal control ureters from patients of similar ages. In comparing ureters with ectopia (7), ureters with ectopic ureteroceles (20) and control ureters (4) there was not a statistically different collagen-to-smooth muscle ratio among the groups. In the patients with posterior urethral valves the amount of collagen and smooth muscle was not statistically different from controls (p > 0.01), although the collagen-to-smooth muscle ratio was increased. The 4 patients with the prune belly syndrome had a collagen-to-smooth muscle ratio that was markedly elevated (1.21 versus 0.39) compared with controls. When this group was analyzed as 2 separate groups (obstructed versus refluxing ureters) the difference was more apparent (p < 0.004). Ureters with ectopia or ectopic ureteroceles and ureters associated with posterior urethral valves had similar quantitative amounts of smooth muscle (60%, 56% and 52%, respectively). In patients with the prune belly syndrome obstructed ureters had 65% muscle and refluxing ureters had 38% muscle on evaluation. The percentage of collagen was 33% in ureters with ectopia, 37% in those with ureteroceles and 48% in those associated with posterior urethral valves compared with 23% in controls. In the group with the prune belly syndrome there was 30% collagen in obstructed ureters and 62% collagen in refluxing ureters. Our findings demonstrate that while these dilated ureters had different etiologies the overall quantitative composition of collagen-to-smooth muscle ratios was similar except in refluxing ureters associated with the prune belly syndrome. Our study provides further insight into the pathological nature of such ureters and considerations for surgical repair.

Inflammatory cell infiltrate in distal ureteral segments from patients with reflux

A total of 110 reimplanted ureters from 61 patients were examined by light microscopy. Twenty-four distal segments from nonrefluxing ureters were used as control group. Overall, 55 of 110 specimens (50%) had inflammatory cell infiltrates (ICI) consisting of lymphocytes and plasma cells in the submucosa and adjacent muscularis. Forty-five ureters (82%) had mild ICI, and 10 ureters (18%) had moderate or severe ICI only in patients with history of infection. ICI increased with grade of reflux in both infected and noninfected groups. Of 75 ureters (68%) from patients with history of infection, 45 (60%) had ICI. Ten of 35 ureters (29%) from patients without history of infection had ICI. A causal relationship between reflux and ICI remains speculative and needs further study.

Vascular integrity of the distal ureter following combined tapering and cross trigonal reimplantation

Massive unilateral hydroureteronephrosis was created in 20 female dogs by ligating the urographically normal prevesical ureter. Over a 14-day period the obstructed ureter dilated to an average of 15.3 mm. A ureteral tapering procedure was performed by lateral darting and posterior folding of the resultant flap, followed by a cross-trigonal reimplantation. One anastomotic stricture resulted; in the remaining 19 animals, ureteral peristalsis was restored, the ureteral diameter was reduced 61.9 per cent and hydronephrosis was resolved. Histological studies on the tapered segments of these 19 animals showed that the subadventitial blood supply was preserved with fibrotic occlusion of the folded flaps. These results demonstrate that no significant vascular compromise after ureteral tapering and cross-trigonal reimplantation occurs. Success rates comparable to those of conventional ureteral tailoring can be achieved by this technically simplified form of reconstructive surgery.

Pathology of ureterorenal units in various ureteral anomalies with particular reference to the genesis of renal dysplasia

Renal morphology of various congenital ureteral anomalies was investigated to gain further insight into the genesis of associated renal dysplasia. Abnormality in the ureteral bud explains the genesis of renal dysplasia as long as the adjoining ureter is cranially ectopic. In caudal ectopy of either single or duplex system, no difference was found in the histologic quality of kidneys with G and H position orifice. In the single system kidneys of H position orifice, however, occurrence of renal dysplasia was not associated with obstruction, suggesting the operation of the "bud theory" even in single system caudal ectopy. In anomalies in which the ureteral orifice was not ectopic, it was suggested that renal parenchymal development was impaired by complete, but not by incomplete obstruction. The association of dysplastic ureter and renal dysplasia was not so frequent as anticipated and the hypodysplastic values of the kidneys with and without dysplastic ureters were similar, suggesting no direct causal relationship between them.

Muscle dysplasia in megaureters

We have previously reported the relevance of muscle dysplasia to the nonreflux megaureter. On electron microscopy, muscle cells which are scattered in large amounts of connective tissue without any bundle formation are found to be deficient in myosin filaments, which, with actin filaments, are believed to be an essential contractile unit of smooth muscle. Investigations of these dysplastic features of the ureter were extended to various other congenital disorders of the ureter experienced in our institution from 1963 to 1981. Muscle dysplasia was found in 8 of 34 cases of nonreflux megaureter, in 1 of 22 cases of reflux megaureter, in 4 of 23 cases of ectopic ureter of single system, in 4 of 9 cases of ectopic ureter of duplex system, 0 of 4 cases of the ureter of ureterocele of single system and in 1 of 13 cases of the ureter of ureterocele of duplex system. When muscle dysplasia was extensive, involving the whole length of the dilated ureter, incidence of associated renal dysmorphism was high in that 12 of 17 ureteral units as such demonstrated either severe renal dysplasia (9) or hypoplasia (3). Similar muscle dysplasia was also found in most of the dome of ureterocele (in 5 of 6 and 12 of 13 ureteroceles of single and duplex systems respectively). Muscle dysplasia is discussed as to its genesis, relevance to various congenital ureteral disorders and clinical implications.