Collagen and elastin in the obstructed fetal bladder

Defining the molecular fingerprint of bladder and kidney fibroblasts

Fibroblasts are integral to the organization and function of all organs and play critical roles in pathologies such as fibrosis; however, we have limited understanding of the fibroblasts that populate the bladder and kidney. In this review, I describe how transcriptomics is leading to a revolution in our understanding of fibroblast biology by defining the molecular fingerprint (i.e., transcriptome) of universal and specialized fibroblast types, revealing gene signatures that allows one to resolve fibroblasts from other mesenchymal cell types, and providing a new comprehension of the fibroblast lineage. In the kidney, transcriptomics is giving us new insights into the molecular fingerprint of kidney fibroblasts, including those for cortical fibroblasts, medullary fibroblasts, and erythropoietin (EPO)-producing Norn fibroblasts, as well as new information about the gene signatures of kidney myofibroblasts and the transition of kidney fibroblasts into myofibroblasts. Transcriptomics has also revealed that the major cell type in the bladder interstitium is the fibroblast, and that multiple fibroblast types, each with their own molecular fingerprint, are found in the bladder wall. Interleaved throughout is a discussion of how transcriptomics can drive our future understanding of fibroblast identification, diversity, function, and their roles in bladder and kidney biology and physiology in health and in disease states.

Studies of ultrastructure, gene expression, and marker analysis reveal that mouse bladder PDGFRA+ interstitial cells are fibroblasts

Fibroblasts are crucial to normal and abnormal organ and tissue biology, yet we lack basic insights into the fibroblasts that populate the bladder wall. Candidates may include bladder interstitial cells (also referred to as myofibroblasts, telocytes, and interstitial cells of Cajal-like cells), which express the fibroblast-associated marker PDGFRA along with VIM and CD34 but whose form and function remain enigmatic. By applying the latest insights in fibroblast transcriptomics, coupled with studies of gene expression, ultrastructure, and marker analysis, we observe the following: 1) that mouse bladder PDGFRA+ cells exhibit all of the ultrastructural hallmarks of fibroblasts including spindle shape, lack of basement membrane, abundant endoplasmic reticulum and Golgi, and formation of homotypic cell-cell contacts (but not heterotypic ones); 2) that they express multiple canonical fibroblast markers (including Col1a2, CD34, LY6A, and PDGFRA) along with the universal fibroblast genes Col15a1 and Pi16 but they do not express Kit; and 3) that PDGFRA+ fibroblasts include suburothelial ones (which express ACTA2, CAR3, LY6A, MYH10, TNC, VIM, Col1a2, and Col15a1), outer lamina propria ones (which express CD34, LY6A, PI16, VIM, Col1a2, Col15a1, and Pi16), intermuscular ones (which express CD34, VIM, Col1a2, Col15a1, and Pi16), and serosal ones (which express CD34, PI16, VIM, Col1a2, Col15a1, and Pi16). Collectively, our study revealed that the ultrastructure of PDFRA+ interstitial cells combined with their expression of multiple canonical and universal fibroblast-associated gene products indicates that they are fibroblasts. We further propose that there are four regionally distinct populations of fibroblasts in the bladder wall, which likely contribute to bladder function and dysfunction.NEW & NOTEWORTHY We currently lack basic insights into the fibroblasts that populate the bladder wall. By exploring the ultrastructure of mouse bladder connective tissue cells, combined with analyses of their gene and protein expression, our study revealed that PDGRA+ interstitial cells (also referred to as myofibroblasts, telocytes, and interstitial cells of Cajal-like cells) are fibroblasts and that the bladder wall contains multiple, regionally distinct populations of these cells.

Layer-dependent role of collagen recruitment during loading of the rat bladder wall

In this work, we re-evaluated long-standing conjectures as to the source of the exceptionally large compliance of the bladder wall. Whereas these conjectures were based on indirect measures of loading mechanisms, in this work we take advantage of advances in bioimaging to directly assess collagen fibers and wall architecture during biaxial loading. A custom biaxial mechanical testing system compatible with multiphoton microscopy was used to directly measure the layer-dependent collagen fiber recruitment in bladder tissue from 9 male Fischer rats (4 adult and 5 aged). As for other soft tissues, the bladder loading curve was exponential in shape and could be divided into toe, transition and high stress regimes. The relationship between collagen recruitment and loading curves was evaluated in the context of the inner (lamina propria) and outer (detrusor smooth muscle) layers. The large extensibility of the bladder was found to be possible due to folds in the wall (rugae) that provide a mechanism for low resistance flattening without any discernible recruitment of collagen fibers throughout the toe regime. For more extensible bladders, as the loading extended into the transition regime, a gradual coordinated recruitment of collagen fibers between the lamina propria layer and detrusor smooth muscle layer was found. A second important finding was that wall extensibility could be lost by premature recruitment of collagen in the outer wall that cut short the toe region. This change was correlated with age. This work provides, for the first time, a mechanistic understanding of the role of collagen recruitment in determining bladder extensibility and capacitance.

Uni-axial stretch induces actin stress fiber reorganization and activates c-Jun NH2 terminal kinase via RhoA and Rho kinase in human bladder smooth muscle cells

Background

Excessive mechanical overload may be involved in bladder wall remodelling. Since the activity of Rho kinase is known to be upregulated in the obstructed bladder, we investigate the roles of the RhoA/Rho kinase pathway in mechanical overloaded bladder smooth muscle cells.

Methods

Human bladder smooth muscle cells were stimulated on silicon culture plates by 15 % elongated uni-axial cyclic stretch at 1 Hz. The activity of c-Jun NH₂-terminal kinase was measured by western blotting and actin stress fibers were observed by stained with phallotoxin conjugated with Alexa-Fluor 594.

Results

The activity of c-Jun NH₂-terminal kinase 1 peaked at 30 min (4.7-fold increase vs. before stretch) and this activity was partially abrogated by the RhoA inhibitor, C3 exoenzoyme or by the Rho kinase inhibitor, Y-27632. Stretch induced the strong formation of actin stress fibers and these fibers re-orientated in a direction that was perpendicular to the stretch direction. The average angle of the fibers from the perpendicular to the direction of stretch was significantly different between before, and 4 h after, stretch. Actin stress fibers reorganization was also suppressed by the C3 exoenzyme or Y-27632.

Conclusions

Bladder smooth muscle cells appear to have elaborate mechanisms for sensing mechanical stress and for adapting to mechanical stress overload by cytoskeletal remodeling and by activating cell growth signals such as c-Jun NH₂-terminal kinase via RhoA/Rho kinase pathways.

Intermittent voiding per urethra as an indicator of cutaneous vesicostomy malfunction

PURPOSE

To present a new approach for management of cutaneous vesicostomy (CV) prolapse, with special emphasis on normal appearing vesicostomy may be malfunctioning. To introduce the application of temporary stoma-free drainage as a diagnostic and therapeutic tool.

MATERIALS AND METHODS

From December 2000 to September 2006, 66 children (61 males and 5 females) with CV were studied. The mean age at vesicostomy was 7 months (range 1-30), and the main underlying disease was posterior urethral valves (in 45 children, 68%). Indications for CV included significant hydroureteronephrosis (HUN) and recurrent urinary tract infection. Patients were followed up for complications and were treated based on our institutional approach. All patients with persistent upper tract dilatation and micturition per urethra underwent temporary bladder (via stoma) free drainage. Patients with stomal stenosis were managed either by a revision surgery or by simple dilatation and intermittent catheterization. Purse string suturing was applied in mucosal prolapses as the first choice.

RESULTS

The complications were observed in 21 patients (31%), including twelve stomal stenosis, nine severe mucosal prolapses, and two recurrent urinary infections. HUN and significant voiding per urethra persisted following initial CV in 19 out of 66 patients (29%), eleven of which having normal appearing CVs. Seventeen of these patients were managed by temporary stoma-free drainage (accompanied by purse string suturing in mucosal prolapse), and two patients with severe stenosis underwent surgical revision. Temporary stoma-free drainage improved HUN in 94% of patients (16 of 17).

CONCLUSIONS

Voiding per urethra is an indicator of CV malfunction, and temporary stoma-free drainage can be a diagnostic and therapeutic option in such children. A seemingly open CV may still be malfunctioning, and ureterovesical or intravesical obstructions should be considered if HUN does not improve following temporary stoma-free drainage.

Long-term consequences of posterior urethral valves

Posterior urethral valves (PUV) are the most common congenital cause of bladder outlet obstruction in infancy, and it is the effect of this obstruction on the bladder and the kidneys that will decide a patient's prognosis. With the improvements in diagnosis and treatments, what was previously a poor prognosis for boys with PUV has improved, and more patients will encounter the long-term sequelae of PUV during puberty and adulthood. In these patients the long-term prognosis in terms of renal and bladder function and fertility, as well as the risk of malignancy in those whose bladders were augmented with gastrointestinal segments, is still a matter of great concern and all of these topics will be discussed in this article.

Altered bladder function in elastin-deficient mice at baseline and in response to partial bladder outlet obstruction

OBJECTIVE

• To examine functional and molecular changes of the bladders from elastin-haploinsufficient mice (Eln(+/-) ) at baseline as well as in response to partial bladder outlet obstruction (pBOO).

MATERIALS AND METHODS

• Female Eln(+/-) and wild type (Wt) mice (3-4 months old) were studied. • The bladder elastin content was quantified by measuring desmosine. • Mice were divided into two groups to undergo surgery to create pBOO or to undergo sham surgery. Three days after surgery, bladder function was evaluated by in vivo cystometry, and the contractile response of bladder strips exposed to electrical field stimulation (EFS) and carbachol was examined by ex vivo myography.

RESULTS

• The Eln(+/-) -sham mice had a 33.6% decrease in bladder elastin compared with Wt-sham mice. • Cystometry showed significantly decreased bladder compliance and capacity in Eln(+/-) -sham vs Wt-sham mice; pBOO increased bladder compliance and capacity to a greater extent in Eln(+/-) mice compared with Wt mice. • Bladder strips from Eln(+/-) -sham mice showed a significantly heightened contractile response to both EFS and carbachol compared with Wt-sham mice. • A significantly increased contractile response to carbachol was detected in Wt-pBOO vs Wt-sham but not between Eln(+/-) -pBOO and Eln(+/-) -sham mice.

CONCLUSION

• The results that elastin-deficient mice had decreased bladder compliance and capacity and increased bladder contractility; and that Wt-pBOO mice showed an enhanced contractile response to carbachol, but Eln(+/-) -pBOO mice did not, suggest that elastin is critical for normal bladder function and is involved in bladder response to pBOO.

Risk factors and treatment success for ureteral obstruction after pediatric renal transplantation

PURPOSE

Risk factors and treatment efficacy for ureteral obstruction following pediatric renal transplantation are poorly understood. We describe a single center experience with pediatric transplant recipients in an effort to discern risk factors and treatment efficacy.

MATERIALS AND METHODS

We retrospectively reviewed the pediatric renal transplant database at our institution from January 1984 to March 2008. Donor and recipient demographics, treatment indications, graft characteristics, surgical techniques, treatment course, complications and graft outcomes were abstracted from clinical records.

RESULTS

A total of 449 children (mean age 8.6 years) who underwent 526 renal transplants were included in the study. Ureteral obstruction requiring intervention developed in 42 cases (8%). Recipient age and gender, recipient and donor race, donor harvest technique, ureterovesical anastomosis with or without stenting, number of donor arteries, number of human leukocyte antigen mismatches, prior renal transplant and ischemia time were not significantly associated with increased incidence of ureteral obstruction. Renal failure secondary to posterior urethral valves was the only parameter significantly associated with increased incidence of ureteral obstruction (univariate OR 4.93, p = <0.0001; multivariate point estimate 7.59, p <0.0001). Of patients with ureteral obstruction 48% presented within 100 days after transplant. Kaplan-Meier analysis showed significantly decreased ureteral obstruction-free survival in patients with vs without posterior urethral valves (log rank test, p <0.0001). Ureteral obstruction, stenting and dilation were not significantly associated with increased graft loss or patient death.

CONCLUSIONS

Ureteral obstruction after renal transplantation in children is a challenging complication that demands clinical vigilance. Posterior urethral valves appear to be a significant risk factor for post-transplant ureteral obstruction likely due to local factors such as ischemia, thick bladder wall and collagen remodeling.

Can a pressure-limited vesico-amniotic shunt tube preserve normal bladder function?

INTRODUCTION

We have previously shown that a vesico-amniotic shunt (V-A shunt) produces fibrotic bladders with poor compliance in normal fetal lambs. We hypothesized that using a ventriculo-peritoneal shunt (V-P shunt) as a V-A shunt in normal bladders may preserve the filling/emptying cycle and normal bladder development.

MATERIALS AND METHODS

The V-A shunting in normal fetal lambs was performed at 74 days of gestation using a V-P shunt (group A) and a free-draining shunt tube (group B). Sham-operated lambs were used as controls (group C). They were all delivered at term (145 days), and the pressure-volume curve, bladder volume, and histologic features of the bladder wall were compared.

RESULT

The mean bladder volume in group B (n = 5), 5 +/- 2.4 mL, was significantly smaller (P < .01) than that in group A (n = 6), 53 +/- 14 mL, and group C (n = 10), 57.3 +/- 12 mL. The bladder wall thickness in group A was 338 + 94.2 microm; group B, 741 +/- 128 microm; and group C, 374 +/- 120 microm. Group B bladders had very poor compliance with thick bladder wall (P < .01). Histologically, group B bladders showed prominent submucosal fibrotic change, but group A bladders were similar to controls.

CONCLUSION

This study shows that a pressure-limited shunt tube for V-A shunting preserves the normal fetal bladder development.

The effects of long-term spinal cord injury on mechanical properties of the rat urinary bladder

We have demonstrated that bladder wall tissue in spinal cord injury (SCI) rats at 10 days post-injury is more compliant and accompanied by changes in material class from orthotropic to isotropic as compared to normal tissue. The present study examined the long-term effects (3-, 6-, and 10-weeks) post-SCI on the mechanical properties of bladder wall tissues, along with quantitative changes in smooth muscle orientation and collagen and elastin content. Bladder wall compliance (defined as det(F) - 1 under an equi-biaxial stress state of 100 kPa, where F is the deformation gradient tensor) was found to be significantly greater at 3- and 6-weeks (0.873 +/- 0.092 and 0.864 +/- 0.112, respectively) when compared to the normal bladders (0.260 +/- 0.028), but at 10 weeks the compliance reduced (0.389 +/- 0.061) to near that of normal bladders. This trend in mechanical compliance closely paralleled the collagen/elastin ratio. Moreover, changes in material class, assessed using a graphical technique, correlated closely with quantitative changes in smooth muscle fiber orientation. The results of the present study provide the first evidence that, while similarities exist between acute and chronic responses of the urinary bladder wall tissue to SCI, the overall alterations are distinct, result in profound and complex time dependent changes in bladder wall structure, and will lay the basis for simulations of the bladder wall disease process.

Time-dependent alterations of select genes in streptozotocin-induced diabetic rat bladder

OBJECTIVES

To investigate time-course changes in the expression of select genes and extracellular matrix proteins in the bladder of rats with streptozotocin-induced diabetes, so as to examine the mechanisms underlying changes in mechanical properties of the bladder due to diabetic cystopathy.

METHODS

Female Sprague-Dawley rats were injected with streptozotocin (65 mg/kg). Rats that were fed with 5% sucrose in drinking water served as diuretic controls, in addition to normal control rats. At the end of 2, 4, and 8 weeks, total ribonucleic acid (RNA) isolated from the detrusor layer of the bladders was reverse transcribed, and then complementary deoxyribonucleic acid was amplified with polymerase chain reaction primer sets for type I collagen, type III collagen, tropoelastin, and transforming growth factor beta 1 (TGF-beta-1). Collagen and elastin contents of the bladders were quantified with commercially available assays.

RESULTS

Both diabetic and diuretic rat bladders exhibited significantly (P <0.05) lower expression of type I collagen and TGF-beta-1 messenger RNA (mRNA) compared with normal controls at all time points tested. In contrast, downregulation of type III collagen mRNA expression in both diabetic and diuretic groups was seen at 4 and 8 weeks. Furthermore, tropoelastin mRNA expression in the diabetic rat bladders was, compared with normal and diuretic rats, significantly (P <0.05) greater at 2 weeks. Both diabetic and diuretic rat bladders exhibited significantly (P <0.05) decreased collagen and increased elastin protein content at 2 and 8 weeks.

CONCLUSIONS

The results of the present study suggest that increases in compliance of the bladders in diabetic cystopathy result not only from diuresis-driven reduction of collagen synthesis but also from increased elastin synthesis.

A porcine model of bladder outlet obstruction incorporating radio-telemetered cystometry

OBJECTIVE

To present a novel porcine model of bladder outlet obstruction (BOO) with a standardized bladder outlet resistance and real-time ambulatory radio-telemetered cystometry, as BOO is a common condition with many causes in both adults and children, with significant morbidity and occasional mortality, but attempts to model this condition in many animal models have the fundamental problem of standardising the degree of outlet resistance.

MATERIALS AND METHODS

BOO was created in nine castrated male pigs by dividing the mid-urethra; outflow was allowed through an implanted bladder drainage catheter containing a resistance valve, allowing urine to flow across the valve only when a set pressure differential was generated across the valve. An implantable radio-telemetered pressure sensor monitored the pressure within the bladder and abdominal cavity, and relayed this information to a remote computer. Four control pigs had an occluded bladder drainage catheter and pressure sensor placed, but were allowed to void normally through the native urethra. Intra-vesical pressure was monitored by telemetry, while the resistance valve was increased weekly, beginning with 2 cmH2O and ultimately reaching 10 cmH2O. The pigs were assessed using conventional cystometry under anaesthesia before death, and samples conserved in formalin for haematoxylin and eosin staining.

RESULTS

The pigs had radio-telemetered cystometry for a median of 26 days. All telemetry implants functioned well for the duration of the experiment, but one pig developed a urethral fistula and was excluded from the study. With BOO the bladder mass index (bladder mass/body mass x 10 000) increased from 9.7 to 20 (P = 0.004), with a significant degree of hypertrophy of the detrusor smooth muscle bundles. Obstructed bladders were significantly less compliant than control bladders (8.3 vs 22.1 mL/cmH2O, P = 0.03). Telemetric cystometry showed that there was no statistically significance difference in mean bladder pressure between obstructed and control pigs (4.8 vs 6.7 cmH2O, P = 0.7), but that each void was longer in the pigs with BOO.

CONCLUSION

This new model of BOO provides a method of reliably and precisely defining the bladder outlet resistance; it induces the changes classically seen with BOO, including increased bladder mass, increased smooth muscle bundle size and decreased compliance.

Vesicostomy vs primary ablation for posterior urethral valves: always a difference in outcome?

OBJECTIVE

A vesicostomy is believed to have a detrimental effect in boys with posterior urethral valves compared to primary valve ablation. We compared the outcomes of boys managed by initial vesicostomy with those undergoing primary fulguration.

MATERIALS AND METHODS

The outcomes of 54 boys (23 vesicostomy, 31 primary valve fulguration) over 1 year of age who had not undergone renal transplant were considered. Outcome parameters identified were ultrasound findings, continence status, glomerular filtration rate (GFR) and 1-year creatinine. Dryness was defined as completely dry both day and night with no need to wear pads. Results are presented with 95% confidence intervals.

RESULTS

Ultrasound examinations were normal in 9/19 (47.4%) of the vesicostomy group and 11/24 (45.8%) of the fulguration group. Graded ultrasound results were not significantly different (p=0.24). The vesicostomy patients were more often dry (79% vs 64%, p=0.43). The vesicostomy group had on average higher GFR (95.26 vs 85.79) and lower 1-year creatinine (49.58 vs 52.46) values. After accounting for age differences between groups, there was no significant difference in the GFR and 1-year creatinine values (p=0.16 and p=0.87, respectively).

CONCLUSIONS

There was a tendency for the major outcomes to be more favourable in the vesicostomy group. Although trends were non-significant, confidence intervals were wide and potential differences of clinical importance could not be discounted.

Ca 2+ Regulation in Detrusor Smooth Muscle From Ovine Fetal Bladder After In Utero Bladder Outflow Obstruction

PURPOSE

We characterized intracellular Ca(2+) regulation in fetal bladders following outflow obstruction by examining the Ca(2+) response to agonists in smooth muscle cells.

MATERIALS AND METHODS

Severe bladder outflow obstruction was induced in male fetal sheep by placing a urethral ring and urachal ligation midway through gestation at 75 days. Fetuses were examined 30 days after surgery. Intracellular Ca(2+) in single smooth muscle cells isolated from the bladder wall was measured with epifluorescence microscopy using fura-2(AM) during exposure to agonists, such as carbachol and adenosine triphosphate, and to other activators, such as caffeine and KCl.

RESULTS

Detrusor smooth muscle cells from obstructed bladders had resting intracellular Ca(2+) similar to that in sham operated controls. The maximal response to carbachol was decreased following obstruction (p <0.05). Construction of dose-response curves also demonstrated higher EC(50) (p <0.05). However, these changes were not mirrored by caffeine evoked Ca(2+) release, which was not significantly different between the obstruction group and sham operated controls. Kinetic analysis of carbachol transients further revealed an attenuated maximal rate of increase in obstructed bladders (p <0.01). The magnitude of intracellular Ca(2+) to purinergic neurotransmitter adenosine triphosphate was also found to be smaller in cells from obstructed bladders (p <0.05), although transmembrane influx by high K depolarization was not significantly affected.

CONCLUSIONS

Muscarinic and purinergic pathways were down-regulated in fetal detrusor muscle following outflow obstruction. These major functional receptors appeared to be more susceptible to obstruction than other Ca(2+) regulators. Their impairment may contribute to the compromised contractile function seen in in utero bladder outflow obstruction.

Detrusor Quantitative Morphometry in Obstructed Males and Controls

PURPOSE

We studied the usefulness of computer assisted morphometry for measuring detrusor muscle cell diameter and the connective tissue-to-smooth muscle ratio in patients with bladder outlet obstruction, acute urinary retention and a nonobstructed control group.

MATERIALS AND METHODS

A prospective study was done in patients with bladder outlet obstruction undergoing transurethral prostate resection. Patients were divided into 33 with obstruction and 14 in acute urinary retention. A total of 15 males without obstruction undergoing transurethral prostate resection for bladder tumor formed the control group. Detrusor specimens were obtained during transurethral prostate resection. Detrusor muscle cell diameter was measured using light microscopy and a semiautomatic image analysis system. The connective tissue-to-smooth muscle ratio was automatically determined with computer assisted image analysis. Symptoms and urodynamic assessment were performed preoperatively and 6 months postoperatively.

RESULTS

A total of 62 patients were included. The obstruction and acute urinary retention groups had a statistically higher detrusor muscle cell diameter and more fibrosis than the control group. Patients in acute urinary retention had more intrafascicular fibrosis (higher connective tissue-to-smooth muscle ratio at 40x magnification) than patients with obstruction. There were no differences in detrusor muscle cell diameter or interfascicular fibrosis (connective tissue-to-smooth muscle ratio at 10x magnification) between the obstruction and acute urinary retention groups. Detrusor muscle cell diameter correlated with symptom duration and functional recovery after transurethral prostate resection. Detrusor fibrosis correlated with preoperative detrusor pressure at maximum flow and postoperative compliance. Patients in acute urinary retention had fewer symptoms and higher residual volume. Other urodynamic parameters and their improvement after surgery were similar in the acute urinary retention and obstruction groups.

CONCLUSIONS

Morphometric differences in detrusor muscle cell diameter and the connective tissue-to-smooth muscle ratio were observed between controls and patients with obstruction. There is an increase in detrusor muscle cell diameter and fibrosis in bladder outlet obstruction and more intense intrafascicular collagen deposition in patients in acute urinary retention.

Management of the valve–bladder syndrome and congenital bladder obstruction: the role of nocturnal bladder drainage

Valve-bladder syndrome often develops after the resolution of posterior urethral valves, but is also found after the resolution of congenital bladder obstruction. The features of this syndrome include the persistent dilation of the upper urinary tracts, a thick-walled, noncompliant urinary bladder, urinary incontinence, and polyuria secondary to nephrogenic diabetes insipidus. Nocturnal bladder management, which involves timed emptying of the bladder or continuous drainage, has been recommended in conjunction with diurnal timed voiding therapy as an adjunct to the treatment of valve-bladder syndrome. This treatment is derived from the hypothesis that valve-bladder syndrome is caused by congenital obstruction, and that the resultant changes in detrusor muscle are associated with a persistent bladder dysfunction characterized by chronic overdistention of the urinary bladder. Such overdistention is exacerbated by polyuria, and can be a cause of secondary hydronephrosis. Bladder dysfunction and overdistention is usually treated during waking time, but occasionally this is not effective on its own, and nocturnal therapy is used as well. To date, there are a few sets of data that suggest overnight bladder drainage can bring about profound improvements in the degree of upper-tract hydronephrosis, renal function, or bladder function. Nocturnal bladder drainage seems, in these initial reports, to be a simple and safe therapeutic maneuver. This review discusses the etiology of valve-bladder syndrome and examines each of the studies which have investigated nocturnal bladder drainage in its treatment.

The Impact of Late Presentation of Posterior Urethral Valves on Bladder and Renal Function

PURPOSE

We retrospectively reviewed the records of patients with late presentation of PUVs, and compared bladder and renal function to that in patients with an early diagnosis of PUVs.

MATERIALS AND METHODS

We retrospectively reviewed the charts of 36 males (mean age at diagnosis 8.8 years, range 5 to 14) with late presentation of PUVs who were treated at our institution between 1986 and 2004. Of these patients 20 had undergone urodynamic evaluation during followup (mean age 10.65 years, range 5 to 23). We chose as controls 19 age matched children with PUVs who were diagnosed and treated before age 5 years and underwent urodynamic evaluation during followup (mean age at urodynamic evaluation 8.52 years, range 6 to 15). Urodynamic parameters were compared between the 2 patient groups. Renal function in the late presenting cases was also compared to controls.

RESULTS

The most common symptoms at presentation were diurnal enuresis (17 patients, 47.2%) poor stream (7, 19.4%) and urinary retention (5, 13.9%). Overall, urodynamic bladder abnormalities were detected in 17 of 20 patients (85%), detrusor overactivity in 3 (15%), significant post-void residual in 9 (45%) and bladder capacity greater than expected for age in 9 (45%). No significant difference in bladder capacity, compliance or post-void residual was demonstrated between the late presenting and control groups. Only detrusor overactivity was significantly lower in the late presenting group (p = 0.013). After a mean followup of 67.03 months age specific creatinine levels were increased in 13 of 27 patients (48.1%), including 7 (25.9%) with ESRD. Renal function was significantly impaired in the late presenting group compared to controls (48.1% vs 13.7%, p = 0.001).

CONCLUSIONS

We found a significantly lower rate of detrusor overactivity (15%) in patients with late presenting PUVs. Comparison of urodynamic parameters between the early and late presenting groups did not reveal any significant difference. This similar pattern of bladder dysfunction, independent of age at relief of obstruction, may indicate a common pathophysiological etiology for bladder dysfunction in all patients with PUVs. Also, renal function was significantly impaired in the late presenting group in this series.

Effects of early vesicostomy in obstructive uropathy on bladder development

PURPOSE

Creation of a vesico-amniotic shunt for obstructive uropathy removes the normal fetal urination cycle. It is unclear how this affects bladder function at term. The authors measured the bladder volume and reviewed the bladder histology after fetal vesicostomy.

METHODS

The authors created an obstructive uropathy in fetal lambs at 60 days' gestation by ligating the urethra and urachus. Vesicostomy (female) or urethrostomy (male) were performed 21 days after obstruction to release the obstruction. The fetuses were killed at term (145 days).

RESULTS

Thirteen fetuses were shunted. Seven fetuses miscarried after shunting. Six survived, and 3 had a successful shunt with a very small bladder (5 to 7 mL). Two had incomplete shunts that failed some time after shunting. These both had huge bladders (399 mL). In one, the obstruction was unsuccessful. Histologic examination showed that the obstruction caused bladder muscle hypertrophy. Shunted lambs had severe fibrosis of the bladder wall and very poor bladder compliance.

CONCLUSIONS

Shunt operations after obstructive uropathy may salvage the kidney but fail to preserve bladder function. The fetus needs a normal urination cycle for normal bladder development. This requirement exists even when the obstruction is successfully bypassed.

CORRELATION BETWEEN DETRUSOR COLLAGEN CONTENT AND URINARY SYMPTOMS IN PATIENTS WITH PROSTATIC OBSTRUCTION

PURPOSE

We used computerized imaging analysis to compare the collagen content of detrusor specimens between patients affected with symptomatic obstructive benign prostatic hyperplasia (BPH) and asymptomatic controls.

MATERIALS AND METHODS

In our study we enrolled 36 patients with symptomatic urodynamically obstructed BPH undergoing transurethral resection of the prostate. We also enrolled 28 men (mean age 61.3, range 55 to 70) undergoing transurethral resection of the bladder for primitive, singular Ta bladder cancer, with no significant urinary symptoms, as the control group. During the transurethral surgical procedure in controls and in patients with BPH, a biopsy was performed deep through the muscular layer from either of the lateral bladder walls. Computerized morphometric analysis of the stained sections was performed with an image analysis system, and a percentage of collagen fibers was extracted through morphological filtering and expressed as a mean percentage of the total bioptic area.

RESULTS

Collagen content in bladder detrusor specimens was significantly higher in patients with BPH compared to controls (48% and 17% of bioptic area, respectively, p <0.001). Mean detrusor collagen content was clearly higher in patients with severe symptoms than in patients with moderate symptoms (50.45 +/- 8.22% and 43.09% +/- 7.05%, respectively).

CONCLUSIONS

Our study supports the important role of detrusor collagen neo-deposition in determining lower urinary tract symptoms in obstructive BPH. Detrusor collagen content correlates with urodynamic obstruction, the presence and severity of symptoms and, given that collagen neoformation is irreversible could probably have a role in the postoperative persistence of lower urinary tract symptoms in patients undergoing surgery for BPH.

Neurotransmission and viscoelasticity in the ovine fetal bladder after in utero bladder outflow obstruction

Fetal bladder outflow obstruction, predominantly caused by posterior urethral valves, results in significant urinary tract pathology; these lesions are the commonest cause of end-stage renal failure in children, and up to 50% continue to suffer from persistent postnatal bladder dysfunction. To investigate the physiological development of the fetal bladder and the response to urinary flow impairment, we performed partial urethral obstruction and complete urachal ligation in the midgestation fetal sheep for 30 days. By electrical and pharmacological stimulation of bladder strips, we found that muscarinic, purinergic, and nitrergic mechanisms exist in the developing fetal bladder at this gestation. After bladder outflow obstruction, the fetal bladder became hypocontractile, producing less force after nerve-mediated and muscarinic stimulation with suggested denervation, and also exhibited greater atropine resistance. Furthermore, fetal bladder urothelium exerted a negative inotropic effect, partly nitric oxide mediated, that was not present after obstruction. Increased compliance, reduced elasticity, and viscoelasticity were observed in the obstructed fetal bladder, but the proportion of work performed by the elastic component (a physical parameter of extracellular matrix) remained the same. In addition to denervation, hypocontractility may result from a reduction in the elastic modulus that may prevent any extramuscular components from sustaining force produced by detrusor smooth muscle.

Early treatment of benign prostatic hyperplasia: implications for reducing the risk of permanent bladder damage

A significant change has occurred in the management of symptomatic benign prostatic hyperplasia (BPH) since effective pharmacological treatment became available and led to a significant decrease in the number of surgical procedures in many Western countries. The hypothesis of a causative role of benign prostatic enlargement and bladder outflow obstruction (BOO) in lower urinary tract symptoms (LUTS) was based on the association between prostate growth and symptoms of prostatism in elderly men and on the dramatic reduction of LUTS upon relief of obstruction. Careful investigation into the epidemiology of LUTS and BPH failed to confirm such an association and opened new perspectives in the pathophysiology of lower urinary tract dysfunction and symptoms. The observation that LUTS were equally distributed in male and female cohorts, when matched for age, moved attention away from the prostate and towards the urinary bladder and its aging-related disorders. When BPH surgery was developed, the management of the disease was aimed at preventing death from chronic renal failure, but the picture has changed and modern medical treatment is now aimed at improving the patient's quality of life. The increasing size of elderly populations in the Western world and the consequent financial constraints of national healthcare systems have raised the question of when pharmacological treatment of symptomatic BPH should be initiated. Retrospective and prospective analysis of various BPH populations and clinical studies has clearly defined the capacity of pharmacological treatment to reduce the incidence of complications of BPH, such as acute urinary retention and the need for surgery, but the cost/benefit ratio is unclear. Notwithstanding the limitations inherent in the experimental models, there is evidence from various animal models, investigating the pathophysiology of the urinary bladder in the presence of outflow obstruction, to indicate that a cause and effect relationship between BOO and bladder decompensation has been established and to support the hypothesis that permanent bladder damage may occur when the obstruction is not relieved early enough. Preliminary experimental evidence also suggests that alpha(1)-adrenoceptor antagonists may have a role in reducing the damaging effects of BOO on the urinary bladder. At present, there is no evidence to support the need for early pharmacological treatment of symptomatic BPH with no BOO beyond the obvious target of improving the patient's quality of life. The evidence for early treatment of BOO and the need to preserve bladder function is clear. Further experimental and clinical research is required to identify markers of early bladder damage and decompensation which can be used to select patients for early pharmacological treatment of BPH.

Morphometric analysis of the collagen changes induced by subcutaneous injection of interferon-gamma after bladder outlet obstruction in the rat

AIMS

The objective of this study was to examine the effects of interferon-gamma injection on changes in collagen content, after the creation of partial bladder outlet obstruction in the rats.

METHODS

A total of 50 Sprague-Dawley female rats were subjected to partial bladder outlet obstruction by using metal rods. The rats were divided into five groups (n = 10 in each group): normal control (N), sham operation (S), bladder outlet obstruction for 4 weeks (BOO), interferon-gamma injection after sham operation (S + IFN), and interferon-gamma injection after bladder outlet obstruction (BOO + IFN). Interferon-gamma was subcutaneously injected (100,000 units per injection, LG chemical Co., Seoul, Korea) daily for 4 weeks in the injection groups, after which all rats were sacrificed.

RESULTS

The collagen area percentage (collagen/collagen + muscle) in each bladder, calculated through image analysis, was 40.7 +/- 1.6% in the N, 38.2 +/- 2.0% in the S, 26.6 +/- 3.8% in the S + IFN, 19.9 +/- 2.5% in the BOO, and 12.4 +/- 2.0% in the BOO + IFN group (mean +/- standard error). The difference in the collagen area percentage between the N and S groups (P > 0.05) was not significant, but there were significant differences between the N and S + IFN groups (P < 0.05), between the S and S + IFN groups (P < 0.05), and between the BOO and BOO + IFN groups (P < 0.05).

CONCLUSIONS

It appears that interferon-gamma decreases the collagen content in the obstructed rat bladder.

Effects of in utero bladder outflow obstruction on fetal sheep detrusor contractility, compliance and innervation

PURPOSE

Congenital bladder outflow obstruction caused by posterior urethral valves is a common cause of end stage renal failure in boys. We hypothesized that fetal bladder outflow obstruction perturbs detrusor contractility and innervation and bladder storage volume-pressure relationships.

MATERIALS AND METHODS

Severe bladder outflow obstruction was induced in male fetal sheep by placing a urethral ring and urachal ligation midway through gestation at 75 days. Fetuses were examined 30 days after surgery, when urinary tract dilatation, enlarged bladders and histologically abnormal kidneys were documented. Isolated strips of bladder detrusor from sham operated and obstructed fetuses were subjected to electrical field stimulation, carbachol, KCl and alpha-beta methylene-adenosine triphosphate. Whole bladder storage characteristics were determined by filling cystometry and bladder innervation was investigated by immunohistochemistry and Western blot.

RESULTS

Tension-frequency contractility studies showed that obstructed fetal bladder strips were significantly hypocontractile versus sham operated controls in response to electrical field stimulation and the specific agonists carbachol, KCl and alpha-beta methylene-adenosine triphosphate. Hypocontractility was greater with nerve mediated stimulation than with carbachol, suggesting relative denervation. Reduced innervation was confirmed by S100 and protein gene product 9.5 immunohistochemistry and by measuring a significant reduction in protein gene product 9.5 protein expression using Western blot. Filling cystometry showed that obstructed fetal bladders appeared more compliant (Delta V/Delta P, where Delta V is the change in volume and Delta P is the change in pressure) with larger capacity, more flaccidity and yet retained stress relaxation.

CONCLUSIONS

In response to severe experimental fetal bladder outflow obstruction the bladder becomes large and hypocontractile, and has aberrant innervation.

Bladder dysfunction as a prognostic factor in patients with posterior urethral valves

OBJECTIVE

To investigate the extent to which different types of bladder dysfunction can affect long-term renal function in boys with posterior urethral valves (PUV).

PATIENTS AND METHODS

Renal and bladder function were retrospectively assessed in 59 boys with PUV (mean age 10 years, range 5-17). All patients included in the study had at least 4 years of follow-up and their bladder behaviour had been evaluated in at least two urodynamic studies. At the time of the study, of the 59 PUV boys, 37 had normal renal function and 22 had end-stage renal disease (ESRD).

RESULTS

Of the 59 boys with PUV evaluated by urodynamic studies, 25 had normally behaving bladders (42%) and 34 had some type of bladder dysfunction (58%). Of the 22 in ESRD, 15 had abnormally behaving bladders (68%) and only seven had bladders with normal behaviour (32%). Of the 37 boys with normal renal function, 19 had dysfunctional bladders (51%) and 18 had normal bladders (49%). Instability was found in 17 of 19 boys with bladder dysfunction and normal renal function. On the contrary among 22 boys with ESRD, poor compliance was the most frequent urodynamic pattern (eight, 53%) while instability was only found in five. Overall, eight of nine boys with poorly compliant bladders, two of three with myogenic failure and a five of 22 with instability were in ESRD, and this situation occurred at an earlier age in patients with poorly compliant bladders.

CONCLUSION

Bladder dysfunction should be considered as a prognostic factor in renal failure. Those with poor bladder compliance and myogenic failure have the worst outcome, while bladder instability was associated with the lowest incidence of renal failure.

The valve bladder: etiology and outcome

The infravesical obstruction created by posterior urethral valves produces a series of structural, biochemical, and functional changes in these boys' bladders that begins during fetal life. Any change can be irreversible and result in the alterations in bladder function that can be found in some of these patients. Bladder instability, poor compliance, and myogenic failure are the three most common urodynamic patterns and are also responsible for some of these patients' poor long-term prognosis. Treatment of bladder dysfunction in these patients is basically directed toward improving their kidney function prognosis and also to avoid the urinary incontinence presented secondarily by some valve bladders.

Essential role for extracellular Ca(2+) in JNK activation by mechanical stretch in bladder smooth muscle cells

Mechanical stretch has been implicated in phenotypic changes as an adaptive response to stretch stress physically loaded in bladder smooth muscle cells (BSMCs). To investigate stretch-induced signaling, we examined the mitogen-activated protein kinase (MAPK) family using rat primary BSMCs. When BSMCs were subjected to sustained mechanical stretch using collagen-coated silicon membranes, activation of c-Jun NH(2)-terminal kinase (JNK) was most relevant among three subsets of MAPK family members: the activity was elevated from 5 min after stretch and peaked at 10 min with an 11-fold increase. Activation of p38 was weak compared with that of JNK, and ERK was not activated at all. JNK activation by mechanical stretch was totally dependent on extracellular Ca(2+) and inhibited by Gd(3+), a blocker of stretch-activated (SA) ion channels. Nifedipine and verapamil, inhibitors for voltage-dependent Ca(2+) channels, had no effect on this JNK activation. Moreover, none of the inhibitors pertussis toxin, genistein, wortmannin, or calphostin C affected stretch-induced JNK activation, indicating that G protein-coupled and tyrosine kinase receptors are unlikely to be involved in this JNK activation. On the other hand, W-7, a calmodulin inhibitor, and cyclosporin A, a calcineurin inhibitor, prevented JNK activation by stretch. These results suggest a novel pathway for stretch-induced activation of JNK in BSMCs: mechanical stretch evokes Ca(2+) influx via Gd(3+)-sensitive SA Ca(2+) channels, resulting in JNK activation under regulation in part by calmodulin and calcineurin.

Aspirin treatment improves bladder function after outlet obstruction in rabbits

OBJECTIVES

To examine whether bladder smooth muscle dysfunction after outlet obstruction could be altered by treatment with aspirin. Long-term outlet obstruction causes contractile and metabolic dysfunction of the bladder in vivo and in vitro. The evidence is growing that a decrease in bladder perfusion is an important cause of this phenomenon. The platelet aggregation inhibitor, acetylsalicylic acid (aspirin), has been used to improve perfusion of the heart for decades.

METHODS

Ten male New Zealand white rabbits were obstructed for 4 weeks. Five rabbits received no further treatment (Obs), and 5 rabbits received 2 mg/kg/day aspirin (Obs+aspirin), administered by an osmotic pump implanted subcutaneously 1 week before the surgical obstruction. The bleeding time was measured to confirm the effectiveness of the aspirin treatment. Three different control groups were created: sham-operated rabbits, unobstructed rabbits with pumps containing DMSO (vehicle), and unobstructed rabbits with pumps containing aspirin. The contractile responses of bladder strips to field stimulation, adenosine triphosphate, carbachol, and KCl were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle and collagen (connective tissue) volume fraction.

RESULTS

No differences were found in the bladder weights or responses to stimuli in the different control groups, which were therefore combined. Partial bladder outlet obstruction caused significant increases in the bladder weight of the obstructed animals (Obs+aspirin, 10.15 +/- 0.87 g; Obs, 10.17 +/- 0.88 g; and controls, 2.87 +/- 0.21 g). The aspirin treatment increased the bleeding time from 1.7 +/- 0.3 minutes to 3.3 +/- 0.1 minutes. The responses to field stimulation were significantly reduced in all of the obstructed rabbits. However, the responses of the bladder strips from the Obs rabbits to field stimulation were impaired to a significantly greater degree than were those from the Obs+aspirin rabbits. The response to 32-Hz stimulation was reduced by 86% in the Obs group but by only 64% in the Obs+aspirin group. The responses to carbachol were significantly reduced by 62% in the strips from the Obs rabbits, but the responses of the strips from the Obs+aspirin rabbits were similar to the responses of the strips from the controls. The responses to KCl and adenosine triphosphate were reduced, although they just failed to achieve statistical significance using Bonferroni's analysis. The ratio of smooth muscle and connective tissue shifted slightly toward smooth muscle after 4 weeks of obstruction, but no difference was found with or without aspirin treatment.

CONCLUSIONS

Low-dose aspirin has a small but significant protective effect on the contractile dysfunction induced by bladder outlet obstruction in rabbits, although the increase in bladder mass was not altered. Bladders of the same weight showed improved responses to all forms of stimulation after pretreatment with aspirin. Already used by millions of patients with heart diseases, aspirin could be a useful protection against contractile dysfunction of the obstructed bladder.

Effect of chronic bladder outlet obstruction on blood flow of the rabbit bladder

PURPOSE

Previous studies have shown that the initial reaction of the rabbit bladder to partial bladder outlet obstruction is increased blood flow at day 1 and a return to baseline blood flow at 1 week. Mucosal and muscle blood flow followed this pattern but mucosal blood flow was always 4 to 5-fold greater. In this study we examined the effect of 4 weeks of outlet obstruction on bladder blood flow and correlated it with the severity of bladder contractile dysfunction.

MATERIALS AND METHODS

A total of 14 male New Zealand White rabbits underwent partial outlet obstruction creation by standard methods. After 4 weeks the rabbits were anesthetized, and blood flow to the muscle and mucosa was determined by standard fluorescent microsphere technique. A section of each detrusor was used for in vitro contractility studies. Contractile responses to field stimulation, carbachol and potassium chloride were determined. A section of each detrusor tissue was fixed in formalin and used to determine the smooth muscle volume fraction.

RESULTS

Four weeks of partial bladder outlet obstruction caused a significant and variable increase in bladder weight and a decrease in blood flow to bladder muscle without changes in the blood flow to mucosa. There was a clear correlation between the severity of contractile dysfunction, bladder weight and the magnitude of the decrease in blood flow in muscle. The smooth muscle volume fraction remained stable at approximately 40%.

CONCLUSIONS

Bladder decompensation was associated with decreased blood flow to bladder smooth muscle. Because compensated obstructed bladders with relatively normal contractile function are also hypertrophied but have normal blood flow, decreased blood flow in decompensated bladders is not simply a response to bladder hypertrophy. From this study we hypothesize that decreased blood flow to bladder smooth muscle is an etiological factor in bladder contractile dysfunction (bladder decompensation) secondary to partial outlet obstruction.

Altered bladder function in transgenic mice expressing rat elastin

The elasticity of tissues subjected to repeated deformation is provided by the presence of elastic fibers in the extracellular matrix (ECM). The most abundant component of elastic fibers is elastin, whose soluble precursor is tropoelastin. To establish the role elastin plays in the bladder, this study describes the biosynthetic, histologic, and physiologic consequences of expression of an isoform of rat tropoelastin in transgenic mouse bladder. The polymerase chain reaction (PCR) was used to determine expression of a rat tropoelastin minigene in transgenic mice. Histochemical methods were used to demonstrate changes in elastic fibers in frozen sections of bladder. Cystometric analysis was carried out in transgenic and non-transgenic mice, prior to and after 3 weeks of partial outlet obstruction. The PCR assay demonstrated that bladder tissue of transgenic mice expressed rat tropoelastin mRNA, whereas non-transgenes did not. Increased deposition of elastic fibers was demonstrated with the Verhoeff-van Gieson stain. Bladders of transgenic animals were more compliant than bladders of their non-transgenic littermates. Partial outlet obstruction resulted in increased bladder volume and more compliant bladders in non-transgenic mice. In contrast, the bladder volume and compliance in transgenes was almost unchanged by obstruction. This study demonstrates that normal elastic fiber assembly is prerequisite for the compliant properties of the bladder wall. Moreover, the response of the bladder to obstruction is critically influenced by elastin synthesis.

Role of type III collagen in bladder filling

The function of the urinary bladder is to store urine at low pressure and expel it periodically. To accomplish this, it must have the appropriate structural properties to accommodate slow but continuous volume changes. While much is presently known about the functional measurements of compliance, relatively little is known about the structural basis of compliance. In the present study, immunohistochemistry has been used to localize type III collagen fibers in the bladder wall at different intravesical volumes. To improve the resolution of these fibers, confocal microscopy was utilized to determine the changes in type III collagen fiber orientation and correlate them with the degree of mechanical distension of the bladder wall at partial and full capacity. We demonstrate that there were significant changes in both the orientation and conformation of type III collagen fibers during bladder filling. These observations support the view that volume accommodation in the bladder is achieved by changes in the arrangement of type III collagen. These data suggest that abnormal deposition or arrangement of type III collagen fibers can have an impact on normal bladder function.

Does treatment of bladder dysfunction prior to renal transplant improve outcome in patients with posterior urethral valves?

Fourteen patients with posterior urethral valves and end-stage renal failure were urodynamically evaluated in order to identify and correct any bladder dysfunction before renal transplant. Of the 14 patients, during filling, six had normal bladder function, two had an over-distended bladder (one with instability), one had instability, four had poor compliance, and one had a very reduced bladder capacity. During the voiding phase, one had a myogenic failure and another had detrusor-sphincteric dyssynergia. Four patients underwent bladder augmentation. Three were managed with anticholinergic therapy and two required clean intermittent catheterization owing to post-voiding residual urine. A renal transplant was performed in all of these patients at a mean age of 8.2 years. We compared outcome in these 14 patients with bladder dysfunction treated before transplantation with outcome in a matched control group of 14 transplant patients. Graft function and survival were similar in both groups. We believe that urodynamic studies must be included in the pretransplant evaluation of patients with posterior urethral valves in order to diagnose any bladder dysfunction and commence appropriate treatment to avoid any negative influence on graft function.

Role of angiotensin II in bladder smooth muscle growth and function

Preliminary studies by our group and others indicate that angiotensin II may have an important role in the cellular regulation of smooth muscle growth and collagen production in the bladder. The exact mechanisms in which angiotensin II elicits its cellular effects are not known. Given the available information thus far, we hypothesize the following (see Figure 2): 1) Outlet obstruction of the bladder causes increased cell stretch/strain which in turn induces the local production of angiotensin II. Angiotensin II may also influence cell stretch/strain via its direct effects on bladder tone. 2) Angiotensin II then acts as a trophic factor in the bladder wall to cause smooth muscle cell hypertrophy/hyperplasia and increased collagen production via an autocrine and/or paracrine pathway. 3) The cellular effect(s) of angiotensin II may be mediated by secondary growth factors such as bFGF and TGFb Much more extensive research is certainly needed to reveal whether some part, or all of this hypothesis is correct. If angiotensin II is indeed active in regulating muscle and collagen changes in the pathologic bladder, then the clinical implications are extremely exciting since numerous pharmacologic agents are now available which can either inhibit angiotensin II production and/or block receptor mediated events. These agents may prove to be extremely useful in the clinical management of the neurogenic bladder in which obstructive changes may be prevented and potentially reversed. Despite this, caution must be exercised with regard to the potential use of any medications which alter the systemic renin-angiotensin system in the pediatric population since some research has suggested that an intact system may be necessary for the normal development of some organs, including the kidney.

The role of collagen in bladder filling

While this model is speculative, it is attractive in that it can account for the physiologic properties of the bladder. It also implies that connections must exist between the tension generating elements, i.e., the smooth muscle cells, and the other components of the bladder. In bladders that become noncompliant, it is likely that there is some interference with the ability of the collagen fibers to elastically and reversibly alter their tortuosity. This, predictably, would reduce total bladder capacity. Further studies will be required to establish the relationship between compliance changes and the passive mechanical elements of the bladder wall that comprise its structural protein matrix.

Focal changes in nerve, muscle and connective tissue in normal and unstable human bladder

OBJECTIVE

To compare and quantify, in a morphological study, the changes that occur in the connective tissue elements (elastin and collagen), muscle fibre diameters and nerve densities between normal, idiopathic and neuropathic bladders.

MATERIALS AND METHODS

Bladder tissue was obtained from 27 patients undergoing cystectomy for carcinoma, from 12 with idiopathic instability and from seven neuropathic patients who were undergoing ileocystoplasty. A combination of histochemical and immunohistochemical techniques were used to detect detrusor muscle, connective tissue and nerve profiles in the bladder tissue.

RESULTS

In both idiopathic and neuropathic bladder tissue the structural changes were highly punctate. From the density of nerve profiles, three areas were defined: (i) apparently unaffected normal fascicles with a high density of nerves, no hypertrophy of the muscle and no infiltration of elastin and collagen. The nerve density in these areas was similar to that in normal bladder tissue. (ii) Fascicles with a low density of nerve profiles, muscle hypertrophy but no connective tissue infiltration. (iii) Areas with few nerve profiles, muscle hypertrophy and extensive elastin and collagen infiltration within the fascicles. The mean (sem) density of nerve profiles in control tissue was 752 (53) nerves/mm2 and in the idiopathic bladders was 905 (91), 81 (20) and 74 (38) nerves/mm2 in the three defined areas, respectively. In the neuropathic tissues the nerve profile densities were 672 (249), 57 (23) and 37 (28) nerves/mm2, respectively. Fibre diameter, elastin and collagen content and nerve density were measured in normal and unstable bladder tissue using these three defined areas. The mean (sem) fibre diameter was 6.81 (0.52) in normal bladder; in idiopathic bladder tissue the fibre diameters in the three areas were 6.72 (0.62), 7.06 (0.62) and 7.34 (1.15) micrometer, respectively, and in neuropathic bladders were 6.75 (0.62), 8.24 (0.62) and 9.35 (0.62) micrometer, respectively. The relative areas of elastin were 0.79 (0.70), 0.56 (0.45) and 18.3 (4.1)% for the control, normal and affected areas of the neuropathic bladders, respectively, and the relative areas of collagen were 3.5 (1.3), 6.15 (3.6) and 15.7 (5. 0)%, respectively. The pattern was similar in idiopathic bladders.

CONCLUSION

These observations suggest that the primary defect in the idiopathic and neuropathic bladders is a loss of nerves accompanied by a hypertrophy of the cells. These changes may continue with further hypertrophy of the cells and an increased production of elastin and collagen within the muscle fascicles.

Follow-up of children after fetal treatment for obstructive uropathy

BACKGROUND

Improvement in the ability to evaluate fetuses with obstructive uropathy, combined with technologic advances, has allowed successful fetal treatment of these conditions in Japan. We analyzed the prenatal and postnatal clinical courses of patients who underwent shunt placement in utero.

METHODS

We treated 6 patients who underwent fetal intervention and were transferred to us for urologic management. Gestational age at detection of abnormalities ranged from 11 weeks to 31 weeks, and fetal intervention was done between 16 weeks and 32 weeks. Excluding 1 infant who was delivered 6 days after the intervention, the mean period between shunt placement and delivery was 17 weeks.

RESULTS

Urologic pathology included prune belly syndrome with urethral hypoplasia in 3 patients, cloacal anomaly in 1, posterior urethral valves in 1, and pelviureteric junction stenosis of a solitary kidney in 1. Four patients required ventilation support in the neonatal period, and 2 of them suffered frequent infections during follow-up. Five patients who underwent vesico-amniotic shunt placement continue to require clean intermittent catheterizations via vesicostomy because of hypoactive detrusors and hypoplastic urethras. After urologic treatment, serum creatinine in 5 patients reached a minimum of less than 0.4 mg/dL at some time during the first year of life. Another patient with a minimum creatinine level of 1.0 mg/dL has moderate renal insufficiency.

CONCLUSION

From our series, it appears that early (before 20 weeks of gestation) shunt placement in severe lower urinary tract obstruction may benefit renal and pulmonary function. However, its efficacy in regard to bladder function remains questionable: shunt placement does not permit regular storage and evacuation, which may be essential for functional bladder development.