Management of the dilated obstructed ureter

Megaureters have been classified as refluxing, obstructed, nonrefluxing-nonobstructed, and refluxing-obstructed. The recommendations for the management of each type are fairly well agreed on. Where controversy has arisen is in the differentiation of the types, especially the primary obstructed from the nonrefluxing-nonobstructed. Distinguishing dilatations that represent significant obstruction from those that apparently are anatomic variants having no detrimental implications for renal function is no simple task, especially in the neonatal infant.     

Nestin expression in the kidney with an obstructed ureter

Nestin is an intermediate filament protein originally identified in neuroepithelial stem cells. This cytoskeletal-associated protein is also expressed in some non-neuronal organs including renal tubular cells and glomerular endothelial cells during kidney development. Little is known, however, about nestin expression in the kidney during injury. In this study, we find nestin expression induced in renal tubular and interstitial myofibroblasts in the adult rat kidney following unilateral ureteral obstruction. The degree of nestin expression was well correlated with the degree of tubulointerstitial fibrosis. Immunohistochemical identification of specific nephron segments showed that nestin was primarily expressed by proximal tubules, partially by distal tubules and thick ascending limbs of Henle but not by collecting ducts. The nestin-positive tubular cells also expressed vimentin and heat-shock protein 47 (HSP47) suggesting these cells reverted to a mesenchymal phenotype. Not all vimentin- or HSP-expressing cells expressed nestin; however, suggesting that nestin is distinct from these conventional mesenchymal markers. Nestin expression was also found associated with phenotypical changes in cultured renal cells induced by hypoxia or transforming growth factor-beta. Nestin expression was located in hypoxic regions of the kidney with an obstructed ureter. Our results indicate that nestin could be a novel marker for tubulointerstitial injury.     

Parathyroid hormone-related protein promotes inflammation in the kidney with an obstructed ureter

Parathyroid hormone-related protein (PTHrP) promotes fibrogenesis in the acutely damaged kidney. Considering the relation between fibrosis and inflammation, we studied transgenic mice that overexpress PTHrP in the proximal tubule. When unilateral ureteric obstruction was induced in these transgenic mice, we found that they had more renal tubulointerstitial damage, leukocyte influx, and expression of proinflammatory factors than their control littermates. Reversal of PTHrP constitutive overexpression in these transgenic mice or treatment of control mice with the PTHrP antagonist (7-34) decreased this inflammatory response. Losartan, which abolished obstruction-induced endogenous PTHrP upregulation, also decreased the latter response but less effectively in transgenic mice. The PTHrP fragment (1-36) induced nuclear factor-kappaB (NF-kappaB) activation and proinflammatory cytokine overexpression in mouse cortical tubule cells in culture as well as migration of the macrophage cell line Raw 264.7. All these effects were decreased by PTHrP (7-34) and NF-kappaB or extracellular signal-regulated kinase (ERK) activation inhibitors. Our findings suggest a critical role of PTHrP in the renal inflammatory process that results from ureteral obstruction and indicate that ERK-mediated NF-kappaB activation seems to be an important mechanism whereby PTHrP triggers renal inflammation.     

Pressure and flow measurements in the partially obstructed ureter of the rat

Hydronephrosis in man or experimental animals can be caused by an increased ureteral flow resistance. This condition can in the long run prove harmful to renal function. We compared two ways of measuring ureteral flow resistance in animals with and without a ureteral hindrance, the hindrance being induced by embedding the ureter in the psoas muscle. One needle connected via catheters to a pressure recording system and another connected to a pump system were introduced through the parenchyma into the renal pelvis. Experiments were carried out with two procedures: 1) infusion of 0.5 ml x min-1 of saline into the renal pelvis was performed while recording the pressure response; 2) a servocontrolled pump system was used which regulated the flow introduced into the renal pelvis to keep a preset pressure at a constant level. In the first group of experiments we did not establish a steady-state pressure despite 20-30 min of infusion. The result from the second series of experiments indicated that steady-state flow measurements could be achieved at the different pressure levels between zero and 30 mmHg. A good linear relationship between pressure and flow was found, even though a considerable hysteresis was observed. Furthermore, a reduced flow resistance down to a certain level at increased pressure was also recorded. As expected, the resistance to flow was significantly lower in the control than in the hydronephrotic animals. In order to investigate the diagnostic ability of the linear relationship between pressure and flow, prediction regions for one future animal were calculated. It seemed possible that determination of the whole pressure-flow relationship in the pressure range between zero and 30 mmHg will prove useful to determine the flow hindrance in hydronephrotic animals.     

The effect of ritodrine and glucagon on the acutely obstructed canine ureter

Summary The effects of 22 g/kg/h glucagon and 240 g/kg/h ritodrine infusions on the electrical activity and the intraluminal pressure of an acutely obstructed canine ureter have been studied. Acute obstruction of the ureter increased the rate of peristalsis from 7.05 (±0.61) to 19.87 (±0.47) per minute and the intraluminal pressure rose to a maximum of 124 cm water. Glucagon and ritodrine infusions reduced the rate of peristalsis to 6.32 (±0.73) and 5.83 (±0.84) respectively, whilst the intraluminal pressure was reduced by 43% during the glucagon infusion and 51% during the ritodrine infusion. The effect of ritodrine was more prolonged than that of glucagon.M. J. Stower was in receipt of a grant from Novo Industries     

The effect of nitric oxide on the pressure of the acutely obstructed ureter

Acute ureteral obstruction leads to changes in pressure inside the ureter, interrupting ureter function. The aim of our study is to explore the relationship between nitric oxide (NO) concentration and pressure in the ureter and to observe the effects of nitric oxide on the revival of renal function. We created the animal models by embedding balloons in the lower ureters of anesthetized dogs and expanding them to simulate acute ureteral obstruction. First, the test animals were pre-treated intravenously with different doses of L-NAME (non-selective nitric oxide synthase inhibitor) to inhibit nitric oxide synthase (NOS), and 10 min later, each subject was administered an intravenous dose of isoproterenol (10 μg/kg). We measured ureter pressure (UP), total and peak concentrations of NO (using an NO monitor, model inNO-T) in ureteral urine, and the volume of the urine (UFV) leaking from the balloon edge. After a certain amount of time had elapsed, it became clear that the dose of L-NAME was inversely related to the total and peak concentrations of NO, the rate of change in UP, and the volume of urine produced. We conclude that L-NAME prevents the NOS from inhibiting the release of NO, then inhibits the effect of isoproterenol reducing the pressure of the acute obstructive ureter. Inversely, we think that NO can reduce the pressure of the acute obstructive ureter and make the obstructive ureter recanalization. And when more the concentration of nitric oxide, the more the pressure will be reduced, and more urine will be collected.     

Endoscopic ureteroureterostomy for a complete obstructed ureter: a case report

We report a case in which the completely obstructed ureter was successfully treated by endourological procedure. The patient was a 66-year-old male who had been admitted for panperitonitis caused by diverticulitis perforation of the sigmoid colon. About one month later, leakage of both stool and urine and left hydronephrosis were observed. Therefore, left percutaneous nephrostomy was performed and the artificial anus was created. Radiographic examination showed about 1 cm defect on the lower one-third of the left ureter. (1st Operation) A 9.5 Fr. rigid ureteroscope was inserted into the left ureter transurethrally and a 7.5 Fr. flexible ureteroscope was inserted percutaneously. Antegrade puncture using a stiff end of a 0.038-inch guidewire into the obstructed segment was failed. Then, we bit off the obliterated tissue with a biopsy forceps transurethrally towards the light from the flexible scope, and a 12 Fr. double-J stent was indwell. (2nd Operation) Eight weeks after the first operation, a 12 Fr. ureteroresectoscope was inserted transurethrally. Full-thickness cold-knife incision of the re-established ureter was failed, however. (3rd Operation) Two weeks after the second operation, a 12.5 Fr. ureteroscope was inserted transurethrally, and a full-thickness incision in the lateral position of the re-established ureter was successfully made by KTP-laser. Then, a 12 Fr. endopyelotomy stent was placed. (Result) Six weeks after the third operation, the stent was removed and DIP revealed the improvement in hydronephrosis. The patient presented no recurrence at 2-year follow up.     

兔输尿管部分梗阻后肾脏血流动力学变化的实验研究

目的研究输尿管部分梗阻后积水肾脏的血流动力学变化。方法以40只实验大白兔制作单侧输尿管部分梗阻模型,于术前、术后1、2、4、8周随机选取10只进行高频彩色多普勒超声测定双侧肾动脉及肾内动脉的血流。结果梗阻后肾血管的血流速度明显降低,且舒张期血流速度降低的程度较收缩期明显得多。肾血管阻力指数逐渐增高,显著高于正常对照。梗阻解除后,肾血流迅速恢复,与正常对照相当。已经发生的病理改变恢复困难,但不再进一步恶化。结论肾脏的血流动力学改变可反映肾脏的功能状态,作为肾功能的评估指标有一定的实用意义。     

Effects of intraluminal hydrostatic pressure on L-methionine absorption in the obstructed small intestine of the rat

The effects of elevated intraluminal hydrostatic pressure on the active absorption of the amino acid selenium 75 L-methionine has been analyzed in the normal and obstructed small intestine. An intestinal loop of defined position and length was included in a recircling perfusion system from which the elimination rate of the radiolabeled amino acid was measured. Preset pressure levels within the system were maintained by a servo-controlled unit, which added or subtracted volume to keep the pressure constant. The rate of amino acid elimination increased when the nonobstructed loop was subjected to a pressure of 10 cm H2O but decreased when exposed to 20cm H2O. Using a loop of intestine subjected to 48 hours of obstruction, amino acid elimination was greatly retarded compared with that of the nonobstructed loop. By increasing the intraluminal pressure to 10 and 20 cm H2O, the elimination rate increased, equalling that of the nonobstructed gut. The results suggest that intestinal obstruction per se decreases active absorption secondary to impaired intestinal viability. Moderately increased intraluminal pressure adds a driving force to L-methionine absorption, the mechanism of which is obscure.     

Over-expression of apoptosis-related proteins contributes to muscular damage in the obstructed ureter of the rat

OBJECTIVE: To determine the role of apoptosis-related proteins (Myc, Bax, Bcl-2, and Bcl-X(L)) in muscular damage in obstructed rat ureters. MATERIALS AND METHODS: The in situ end-labelling of DNA fragments and the expression of apoptosis-related proteins were assessed, using immunohistochemistry, in 54 female Sprague-Dawley rats in which unilateral ureteric obstruction was caused by ureteric ligation. RESULTS: The severity of ureteric damage increased during the period of obstruction. Apoptotic cells and the expression of Bax were detected in the smooth muscle layer from 14 days after ligation. The percentage of apoptotic cells and the expression of Bax in the smooth muscle layer increased and reached a peak 21 days after ligation, and then declined. The expression of Myc was also detected in the smooth muscle layer 14 days after ligation but reached a peak at 28 days. The expressions of Bcl-2 and Bcl-X(L) in the smooth muscle layer were only detected 21 and 28 days after ligation. The numbers of apoptotic cells in the smooth muscle layer correlated significantly with the expressions of Myc and Bax (r = 0.7360 and 0.7432, respectively; both P < 0.005), and with the expression index of Bax/Bcl-2 and Bax/Bcl-X(L) (r = 0.8909 and 0.8592, respectively; both P < 0.001). CONCLUSIONS: Apoptosis-related proteins might be important in regulating cell apoptosis in ureteric damage during the development of obstructive uropathy.     

Double-nippled ureteroneocystostomy: A novel surgical technique in the management of the obstructed dilated ureter

Objective

To present the outcome of double-nippled ureteroneocystostomy as a novel technique in the treatment of the dilated obstructed distal ureter.

Patients and Methods

The technique was performed in 55 patients with lower ureteric stricture. The lowest segment of the dilated obstructed ureter is transected and passed through the bladder dome for ureterovesical implantation. The distal 3 cm is folded twice like a sleeve to fashion a double-nippled valve. Evaluation of the appearance and function of the ureter and ipsilateral renal function was done by laboratory, imaging and endoscopic studies at 3, 6 and 12 months following surgery, then annually.

Results

Functional and morphological improvement was observed in 80% of the cases. Imaging and endoscopic verification of the valve stability and ipsilateral renal unit status, integrity and patency were confirmed in all patients but two (3.6%) who developed grade 2 vesico-ureteric reflux.

Conclusion

Double-nippled ureteroneocystostomy is a safe and efficient surgical modality for the management of the dilated ureter due to bilharzial stricture.     

Experience with the ileal ureter.

The isolated ileal loop often provides a satisfactory solution to the problem of extensive ureteric defects. Our experience in 18 cases of diseased ureters partially or totally replaced by isolated ileal loops is presented. The indications for the operation and important operative and preoperative details are discussed. The operation presents a definite method for renal conservation in many cases in which nephrectomy would otherwise have been unavoidable.     

Serial microscopic changes in cell proliferation and apoptosis in obstructed ureter of rat

PURPOSE: We investigated the histologic findings and serial changes in cell proliferation and apoptosis in obstructed rat ureters. MATERIALS AND METHODS: After unilateral ligation of the ureter, animals from each of five groups of Sprague- Dawley rats were sacrificed for examination at 1, 5, 10, 15, 20, 25, 30, or 35 days. Cell division was detected with proliferating cell nuclear antigen (PCNA) immunohistochemistry, and apoptosis was detected with terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) in-situ nick-end labeling (TUNEL) study. RESULTS: The epithelial layer was thickened in 5-day-obstructed ureters (5 DOUs). The severity of thickening of the fibrous and smooth-muscle layers progressed consistently to 15 DOUs and were maintained in 35 DOUs. Expression of PCNA in the epithelial layer was present in every ureter, and a significant increase in the number of labeled cells was present in 1 and 5 DOUs. Expression of PCNA in the fibrous and smoothmuscle layers was detectable in 10 DOUs and was maintained in 20 DOUs, after which, it declined significantly in the 25 DOUs. TUNEL-positive cells in the epithelial layer were shown in 10, 15, 20, 25, 30, and 35 DOUs, with the peak being reached at 25 days. TUNEL-positive cells in the fibrous and smooth-muscle layers were found in 25, 30, and 35 DOUs. CONCLUSIONS: Cell proliferation and apoptosis may play an important role in the pathogenesis of damage in obstructed ureters. Peak times of proliferation and apoptosis were different in the epithelial and fibrous and smooth-muscle layers.     

Effects of intraluminal pressure on regional blood flow in obstructed and unobstructed small intestines in the rat

Small bowel circulation in the rat was studied with the microsphere technique before and after 10 minutes of elevated intraintestinal pressure. A distal small bowel loop consisting of 10 vascular arcades was used. The specimens were inflated with nitrogen gas. Regional blood flow in both obstructed and unobstructed small bowels was significantly diminished by an intraintestinal pressure of 40 mm Hg. A pressure of 20 mm Hg impaired circulation only in the obstructed small intestine, whereas the unobstructed intestine did not show a similar decrease. These findings suggest that moderate intraluminal pressures can imply a potential hazard to the vulnerable capillary bed of an obstructed intestine. Hence, it is suggested that intraoperative decompression should be performed to avoid this postoperative threat to bowel viability.