The detrusor muscle: an innocent victim of bladder outlet obstruction

Does prostate size predict the urodynamic characteristics and clinical outcomes in benign prostate hyperplasia?

Aims:

Bladder outlet obstruction (BOO) in large and small prostates is managed in a similar manner despite considerably different pathophysiology, which can result in higher failure rates. We investigate the clinical and urodynamic features and study the outcome of patients with benign prostate hyperplasia (BPH) according to their prostate size.

Subjects and Methods:

We prospectively analyzed 100 BPH patients undergoing urodynamic study between January 2015 and August 2016 and divided them into two groups according to their prostate size: small (≤30 mL) and large prostate (>30 mL) groups. We compared the groups regarding age, International Prostate Symptom Score, maximal flow rate (Qmax), postvoided residual, serum prostate-specific antigen (PSA), prostate volume measured by ultrasonography (USG), and urodynamic findings.

Statistical Analysis Used:

For testing the hypothesis, we used the Chi-square test, Student's t-test, and one-way analysis of variance when comparing between groups and conducted the logistic regression analysis for determining predictive factors of BOO.

Results:

Although the total prostate volume significantly correlated with the PSA, patients with a small prostate had lower Qmax (5.27 ± 4.8 mL/s vs. 6.14 ± 6.66 mL/s; P = 0.74), higher incidence of abnormal baldder capacity (39.9% vs. 31.25%), lower voiding efficiency (39.3 ± 40.5% vs. 40.57 ± 32.11%), low compliance (44.4% vs. 31.3%), higher incidence of indeterminate detrusor contractions (38.9% vs. 37.5%), lower incidence of detrusor underactivity (33.3% vs. 28.1%), lower BOO index (40.9 ± 43.2 vs. 49.10 ± 44.48), lower bladder contractility index (77.8 ± 48.84 vs. 92.09 ± 52.79), and lower PdetQmax (51.44 ± 42.23 vs. 61.38 ± 42.01 cmH₂O). Small prostates had higher failed voiding trials postsurgery.

Conclusions:

BOO patients with a small prostate showed poor urodynamic parameters and reported higher postoperative complications.

Evaluation and Management of Lower Urinary Tract Symptoms After Outlet Surgery for Benign Prostatic Hyperplasia

There are many options available in the surgical treatment of outlet obstruction secondary to benign prostatic hyperplasia (BPH). While most patients exhibit improvement in their lower urinary tract symptoms (LUTS) following intervention, up to 35 % of patients may exhibit persistent or recurrent LUTS. In the present review, we discuss the patho-physiology of LUTS after bladder outlet surgery and discuss considerations in evaluating and managing such patients. We highlight the crucial role of thorough evaluation with complete urodynamics testing, as pure obstruction only accounts for a minority of post-operative LUTS. Hence, detrusor contractility, detrusor overactivity, urethral sphincter function, and urinary incontinence must be assessed to appropriately guide subsequent therapy and improve patients' quality of life.

Eight-Year Experience With Botulinum Toxin Type-A Injections for the Treatment of Nonneurogenic Overactive Bladder: Are Repeated Injections Worthwhile?

Purpose:

To investigate the efficacy and safety of repeated botulinum toxin type-A (BTX-A) injections for patients with drug-refractory nonneurogenic overactive bladder (NNOAB) and explore factors predictive of outcome.

Methods:

Data were collected from all patients receiving repeated BTX-A injections for drug-refractory NNOAB between 2004 and 2012. Trigone-sparing injections were administered under sedation with antibiotic prophylaxis. Patient characteristics including age, sex, preoperative urodynamics, injection number, BTX-A dose, complications, and patient global impression of improvement (PGI-I) scores were collected. Correlations between patient factors and outcomes were assessed by using Pearson’s chi-square tests.

Results:

Fifty-two patients with a mean age of 67.4 years (range, 26–93 years) received 140 BTX-A injections in total; 33 (64%), 15 (29%), and 4 patients (7%) received 2, 3 to 4, and 5 to 8 injections, respectively. Mean follow-up time was 49 months (range, 9–101 months). Nine patients developed urinary tract infection; additionally, 3 patients experienced transient urinary retention. Median PGI-I score was 2 out of 7 (interquartile range [IQR], 2). For 46 patients, the PGI-I score remained stable with the administration of each injection. Pearson chi-square tests revealed that male patients or reduced bladder compliance was associated with a higher (worse) PGI-I score. Median PGI-I scores for men and women were 3 (IQR, 1) and 2 (IQR, 1), respectively; additionally, median PGI-I scores for those with normal bladder compliance and those with reduced bladder compliance were 2 (IQR, 2) and 4.5 (IQR, 1), respectively. Median PGI-I scores and complication rates were the same in the older patient (≥70 years) and younger (<70 years) patient cohorts.

Conclusions:

Efficacy is maintained with repeated BTX-A injections. Patients including the elderly show a good degree of tolerability with a low complication rate. Male patients or reduced bladder compliance is associated with poorer outcomes.

Efficacy of Adding Dutasteride to α-Blocker Therapy Treated Benign Prostatic Hyperplasia Patients with Small Volume Prostate (<30 mL)

OBJECTIVES

To assess the efficacy of dutasteride add-on therapy for patients with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS) with small prostates who have been treated with α-blocker therapy for >3 months.

METHODS

A total of 110 men with clinical BPH were enrolled. There were 17 and 93 subjects with a prostate volume (PV) <30 and ≥30 mL, respectively. All subjects had been treated with α-blocker therapy for >3 months. Subjective and objective clinical variables were assessed using the total International Prostate Symptom Score (IPSS-T), IPSS quality of life (IPSS-QoL), IPSS voiding subscore (IPSS-V), IPSS storage subscore (IPSS-S), overactive bladder symptom score (OABSS), PV, prostate specific antigen (PSA) level, post-void residual (PVR), and maximum flow rate (Qmax). These variables were assessed at baseline and every 3 months for 1 year.

RESULTS

In the small prostate group, IPSS-T and IPSS-V showed improvements from baseline at 6 and 9 months, storage subscore at 6 months, and OABSS at 3 months, but no sustained improvements were observed. During the study period, only the IPSS QoL scores did not show any improvement. Conversly, dutasteride was significantly effective at improving IPSS-T, IPSS-V, IPSS-S, and IPSS-QoL scores throughout the study period in the large prostate BPH group. PSA levels and PV significantly decreased in both groups throughout the study.

CONCLUSIONS

Benign prostatic hyperplasia in LUTS patients with small prostates did not show a sustainable benefit from the addition of dutasteride to α-blocker therapy.

Urodynamic Features and Significant Predictors of Bladder Outlet Obstruction in Patients With Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia and Small Prostate Volume

OBJECTIVE

To investigate the clinical and urodynamic features of patients with lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH) according to their prostate size.

MATERIALS AND METHODS

We analyzed 2039 LUTS/BPH patients who underwent urodynamic study between October 2004 and August 2013. We divided the patients into three groups according to their prostate size: small (≤30 mL), moderately enlarged (31-80 mL), and large prostate (≥81 mL) groups. We compared the groups regarding age, International Prostatic Symptom Score, maximal flow rate (Qmax), postvoided residual (PVR), serum prostate-specific antigen, prostate volume measured by ultrasonography, and urodynamic findings.

RESULTS

Patients with a small prostate had better urodynamic outcomes than those with larger prostates in overall population. Although the total prostate volume significantly correlated with the bladder outlet obstruction (BOO) index (r  =  0.51), BOO patients with a small prostate had similar Qmax, higher PVR, and lower voiding efficiency, compared to those with larger prostates. Moreover, urodynamic parameters indicating bladder abnormalities, including low compliance and involuntary detrusor contraction positivity, were similar among the groups in BOO patients. A higher proportion of detrusor underactivity was also observed in the small prostate group in BOO patients. Finally, when adjusting for potential confounding variables, we identified serum prostate-specific antigen levels (odds ratio, 1.34) and Qmax (odds ratio, 0.77) as significant predictors for BOO in LUTS/BPH patients with a small prostate.

CONCLUSION

BOO patients with a small prostate showed higher PVR and poor voiding efficiency, as well as similar urodynamic bladder abnormalities, compared to those with moderately enlarged and large prostates.

Impairment of ATP hydrolysis decreases adenosine A1 receptor tonus favoring cholinergic nerve hyperactivity in the obstructed human urinary bladder

This study was designed to investigate whether reduced adenosine formation linked to deficits in extracellular ATP hydrolysis by NTPDases contributes to detrusor neuromodulatory changes associated with bladder outlet obstruction in men with benign prostatic hyperplasia (BPH). The kinetics of ATP catabolism and adenosine formation as well as the role of P1 receptor agonists on muscle tension and nerve-evoked [(3)H]ACh release were evaluated in mucosal-denuded detrusor strips from BPH patients (n = 31) and control organ donors (n = 23). The neurogenic release of ATP and [(3)H]ACh was higher (P < 0.05) in detrusor strips from BPH patients. The extracellular hydrolysis of ATP and, subsequent, adenosine formation was slower (t (1/2) 73 vs. 36 min, P < 0.05) in BPH detrusor strips. The A(1) receptor-mediated inhibition of evoked [(3)H]ACh release by adenosine (100 μM), NECA (1 μM), and R-PIA (0.3 μM) was enhanced in BPH bladders. Relaxation of detrusor contractions induced by acetylcholine required 30-fold higher concentrations of adenosine. Despite VAChT-positive cholinergic nerves exhibiting higher A(1) immunoreactivity in BPH bladders, the endogenous adenosine tonus revealed by adenosine deaminase is missing. Restoration of A1 inhibition was achieved by favoring (1) ATP hydrolysis with apyrase (2 U mL(-1)) or (2) extracellular adenosine accumulation with dipyridamole or EHNA, as these drugs inhibit adenosine uptake and deamination, respectively. In conclusion, reduced ATP hydrolysis leads to deficient adenosine formation and A(1) receptor-mediated inhibition of cholinergic nerve activity in the obstructed human bladder. Thus, we propose that pharmacological manipulation of endogenous adenosine levels and/or A(1) receptor activation might be useful to control bladder overactivity in BPH patients.

Activation of common signaling pathways during remodeling of the heart and the bladder

The heart and the urinary bladder are hollow muscular organs, which can be afflicted by pressure overload injury due to pathological conditions such as hypertension and bladder outlet obstruction. This increased outflow resistance induces hypertrophy, marked by dramatic changes in the organs' phenotype and function. The end result in both the heart and the bladder can be acute organ failure due to advanced fibrosis and the subsequent loss of contractility. There is emerging evidence that microRNAs (miRNAs) play an important role in the pathogenesis of heart failure and bladder dysfunction. MiRNAs are endogenous non-coding single-stranded RNAs, which regulate gene expression and control adaptive and maladaptive organ remodeling processes. This Review summarizes the current knowledge of molecular alterations in the heart and the bladder and highlights common signaling pathways and regulatory events. The miRNA expression analysis and experimental target validation done in the heart provide a valuable source of information for investigators working on the bladder and other organs undergoing the process of fibrotic remodeling. Aberrantly expressed miRNA are amendable to pharmacological manipulation, offering an opportunity for development of new therapies for cardiac and bladder hypertrophy and failure.

Postoperative Lower Urinary Tract Storage Symptoms: Does Prostate Enucleation Differ from Prostate Vaporization for Treatment of Symptomatic Benign Prostatic Hyperplasia?

PURPOSE

To assess the degree of postoperative storage symptoms after GreenLight™ laser photoselective vaporization of the prostate (PVP) and Holmium laser enucleation of the prostate (HoLEP) for management of benign prostatic hyperplasia (BPH) and its predictors.

METHODS

A retrospective review was performed for patients who underwent HoLEP or PVP for non catheter-dependent patients with BPH. Patients were followed up at 1, 3, 6, and 12 months and then annually by International Prostate Symptoms Score (IPSS), quality of life index, peak flow rate, residual urine volume, and prostate-specific antigen (PSA) level. Moderate or severe storage symptoms were defined as IPSS storage subscore ≥ 9.

RESULTS

Of 1673 laser procedures, a total of 1100 procedures met the inclusion criteria including 809 HoLEPs and 291 PVPs. The HoLEP group had significantly larger preoperative prostates and longer operative time. In the HoLEP group, postoperative IPSS was significantly better than in the PVP group at all follow-up points (P<0.05). Storage subscore was significantly higher after PVP and did not improve until 6 months postoperatively when it became comparable with that of the HoLEP group. The number of patients with IPSS-storage score ≥ 9 were significantly higher in the PVP group at 1 and 3 months follow-up (37.3% vs 15.1%, P<0.001) and (26.4% vs 17.5%, P=0.004), respectively. XPS-180W was associated with the lowest storage symptoms among the three GreenLight generations at all follow-up visits. In multivariate analysis, baseline IPSS-storage subscore ≥ 9, prolonged operative time >100 minutes, and lower percent of postoperative PSA level reduction significantly predicted less improvement of postoperative storage symptoms regardless of the laser procedure.

CONCLUSION

Storage urinary symptoms significantly improved more after HoLEP compared with PVP, irrespective of the generation of GreenLight laser used. Recovery from bothersome storage urinary symptoms after prostate vaporization is time dependent, and baseline degree of storage symptoms, prolonged operative time, and lower percent of postoperative PSA level reduction negatively predicts postoperative improvement of storage symptoms regardless of the laser procedure.

Activation of P2Y6 Receptors Facilitates Nonneuronal Adenosine Triphosphate and Acetylcholine Release from Urothelium with the Lamina Propria of Men with Bladder Outlet Obstruction

PURPOSE

Deregulation of purinergic bladder signaling may contribute to persistent detrusor overactivity in patients with bladder outlet obstruction. Activation of uridine diphosphate sensitive P2Y6 receptors increases voiding frequency in rats indirectly by releasing adenosine triphosphate from the urothelium. To our knowledge this mechanism has never been tested in the human bladder.

MATERIALS AND METHODS

We examined the role of the uridine diphosphate sensitive P2Y6 receptor on tetrodotoxin insensitive nonneuronal adenosine triphosphate and [(3)H]acetylcholine release from the human urothelium with the lamina propria of control organ donors and patients with benign prostatic hyperplasia.

RESULTS

The adenosine triphosphate-to-[(3)H]acetylcholine ratio was fivefold higher in mucosal urothelium/lamina propria strips from benign prostatic hyperplasia patients than control men. The selective P2Y6 receptor agonist PSB0474 (100 nM) augmented by a similar amount adenosine triphosphate and [(3)H]acetylcholine release from mucosal urothelium/lamina propria strips from both groups of individuals. The facilitatory effect of PSB0474 was prevented by MRS2578 (50 nM) and by carbenoxolone (10 μM), which block P2Y6 receptor and pannexin-1 hemichannels, respectively. Blockade of P2X3 (and/or P2X2/3) receptors with A317491 (100 nM) also attenuated release facilitation by PSB0474 in control men but not in patients with benign prostatic hyperplasia. Immunolocalization studies showed that P2Y6, P2X2 and P2X3 receptors were present in choline acetyltransferase positive urothelial cells. In contrast to P2Y6 staining, choline acetyltransferase, P2X2 and P2X3 immunoreactivity decreased in the urothelium of benign prostatic hyperplasia patients.

CONCLUSIONS

Activation of P2Y6 receptor amplifies mucosal adenosine triphosphate release underlying bladder overactivity in patients with benign prostatic hyperplasia. Therefore, we propose selective P2Y6 receptor blockade as a novel therapeutic strategy to control persistent storage symptoms in obstructed patients.

Research Findings on Overactive Bladder

Several physiopathologic conditions lead to the manifestation of overactive bladder (OAB). These conditions include ageing, diabetes mellitus, bladder outlet obstruction, spinal cord injury, stroke and brain injury, Parkinson's disease, multiple sclerosis, interstitial cystitis, stress and depression. This review has discussed research findings in human and animal studies conducted on the above conditions. Several structural and functional changes under these conditions have not only been observed in the lower urinary tract, but also in the brain and spinal cord. Significant changes were observed in the following areas: neurotransmitters, prostaglandins, nerve growth factor, Rho-kinase, interstitial cells of Cajal, and ion and transient receptor potential channels. Interestingly, alterations in these areas showed great variation in each of the conditions of the OAB, suggesting that the pathophysiology of the OAB might be different in each condition of the disease. It is anticipated that this review will be helpful for further research on new and specific drug development against OAB.

Prostatic inflammation induces urinary frequency in adult mice

Lower urinary tract symptoms (LUTS) including urinary frequency and nocturia are common in aging men. Recent studies have revealed a strong association of prostatic inflammation with LUTS. We developed an animal model of bacterial induced, isolated prostatic inflammation and examined the effect of prostatic inflammation on voiding behavior in adult C57BL/6J mice. Prostatic inflammation was induced by transurethral inoculation of uropathogenic E. coli—1677. Bacterial cystitis was prevented by continuous administration of nitrofurantoin. Hematoxylin and eosin (H&E) staining and bacterial culture were preformed to validate our animal model. Voiding behavior was examined by metabolic cage testing on post-instillation day 1 (PID 1), PID 4, PID 7 and PID 14 and both voiding frequency and volume per void were determined. Mice with prostatic inflammation showed significantly increased voiding frequency at PID 1, 7 and 14, and decreased volume per void at all time points, as compared to mice instilled with saline and receiving nitrofurantoin (NTF). Linked analysis of voiding frequency and voided volumes revealed an overwhelming preponderance of high frequency, low volume voiding in mice with prostatic inflammation. These observations suggest that prostatic inflammation may be causal for symptoms of urinary frequency and nocturia.

Change in storage symptoms following laser prostatectomy: comparison between photoselective vaporization of the prostate (PVP) and holmium laser enucleation of the prostate (HoLEP)

PURPOSE

To compare serial changes of postoperative storage symptoms between PVP and HoLEP, and to identify the predictors influencing postoperative improvement of storage symptoms.

METHODS

A total of 486 men (PVP group: 213 cases; HoLEP group: 273 cases), in whom 12-month follow-up data were available, were included in this retrospective study. Surgical outcomes were evaluated at 1-, 3-, 6-, and 12 months postoperatively using the IPSS, uroflowmetry with post-void residual urine volume (PVR) and serum PSA levels. Improvement of storage symptoms was defined as a reduction by ≥50 % of the subtotal storage symptom score postoperatively compared to baseline.

RESULTS

In both PVP and HoLEP groups, total IPSS, quality-of-life index, frequency score, nocturia score, maximum flow rate and PVR were significantly decreased compared to baseline starting from 1 month after surgery. Whereas urgency score was numerically increased compared to baseline at 1 month after PVP, it was reduced compared to baseline at 1 month after HoLEP. While the subtotal storage symptom score was significantly decreased compared to baseline starting from 3 months after PVP, it was significantly reduced starting from 1 month after HoLEP. On logistic regression analysis, a higher baseline subtotal storage symptom score was the only independent predictor of improvement in storage symptoms after PVP or HoLEP.

CONCLUSIONS

Our data suggest that improvement in storage symptoms after HoLEP begins earlier than that after PVP. Also, this study indicates that patients with more severe baseline storage symptoms have a higher likelihood of improvement after PVP or HoLEP compared to those with less severe symptoms.

The urinary bladder of spontaneously hypertensive rat demonstrates bladder hypertrophy, inflammation, and fibrosis but not hyperplasia

AIMS

The present study aims to systemically characterize the factors that are associated with urinary bladder organ enlargement in spontaneously hypertensive rats (SHR).

MAIN METHODS

We compared the SHR to age-matched normotensive Wistar-Kyoto (WKY) control rats in the levels of bladder pro-inflammatory factors, collagen expression (type I), and detrusor smooth muscle growth.

KEY FINDINGS

Our results showed that enhanced inflammatory responses and fibrosis were key factors that were closely associated with bladder wall thickening in SHR. Specifically the mRNA levels of inflammatory factors interleukin (IL)-1α, IL-6 and TNFα were significantly higher in SHR than those in WKY rats. The SHR also had a higher number of mast cells in the suburothelium space. Type I collagen production was also significantly higher in SHR when compared to that in control rats. However, the smooth muscle content stayed the same in SHR and WKY rats. This was shown by the results that the ratio of α-smooth muscle actin (SMA) to the nuclear protein histone H3 had no difference between these two rat strains. The mRNA and protein levels of proliferating cell nuclear antigen (PCNA) also showed no change in the urinary bladder of SHR and WKY rats. Further study showed that the phosphorylation level of Akt in the urinary bladder was not changed in SHR when compared to WKY rats. In contrast, the phosphorylation level of ERK1/2 was significantly higher in SHR bladder when compared to that of WKY rats.

SIGNIFICANCE

These results suggest that inflammation and fibrosis are primary factors that may lead to urinary bladder hypertrophy in SHR.

Mechanical stretch upregulates proteins involved in Ca2+ sensitization in urinary bladder smooth muscle hypertrophy

Partial bladder outlet obstruction (pBOO)-induced remodeling of bladder detrusor smooth muscle (DSM) is associated with the modulation of cell signals regulating contraction. We analyzed the DSM from obstructed murine urinary bladders for the temporal regulation of RhoA GTPase and Rho-activated kinase (ROCK), which are linked to Ca(2+) sensitization. In addition, the effects of equibiaxial cell stretch, a condition thought to be associated with pBOO-induced bladder wall smooth muscle hypertrophy and voiding frequency, on the expression of RhoA, ROCK, and C-kinase-activated protein phosphatase I inhibitor (CPI-17) were investigated. DSM from 1-, 3-, 7-, and 14-day obstructed male mice bladders and benign prostatic hyperplasia (BPH)-induced obstructed human bladders revealed overexpression of RhoA and ROCK-β at the mRNA and protein levels compared with control. Primary human bladder myocytes seeded onto type I collagen-coated elastic silicone membranes were subjected to cyclic equibiaxial stretch, mimicking the cellular mechanical stretch in the bladder in vivo, and analyzed for the expression of RhoA, ROCK-β, and CPI-17. Stretch caused a significant increase of RhoA, ROCKβ, and CPI-17 expression. The stretch-induced increase in CPI-17 expression occurs at the transcriptional level and is associated with CPI-17 promoter binding by GATA-6 and NF-κB, the transcription factors responsible for CPI-17 gene transcription. Cell stretch caused by bladder overdistension in pBOO is the likely mechanism for initiating overexpression of the signaling proteins regulating DSM tone.

Management of the complications of BPH/BOO

Most men will develop histological BPH if they live long enough. Approximately, half will develop benign prostatic enlargement (BPE) and about half of these will get BOO with high bladder pressures and low flow, this in turn leads to detrusor wall hypertrophy. Many of these men will only have lower urinary tract symptoms (LUTS) but a significant number will also suffer the other complications of BPH. These include urinary retention (acute and chronic), haematuria, urinary tract infection, bladder stones, bladder wall damage, renal dysfunction, incontinence and erectile dysfunction. Recognition of the complications of BPH/BOO early allows more effective management of these complications. This is particularly important for the more serious urinary infections and also for high-pressure chronic retention (HPCR). Complications of LUTS/BPH are very rare in clinical trials because of their strict inclusion and exclusion criteria but are more common in real life practice.

Which patients are at higher risk for residual valves after posterior urethral valve ablation?

Purpose

To find patients at high risk of obstructive remnant leaflets after valve ablation among boys with posterior urethral valve (PUV), we evaluated any possible relationship between preoperative findings in our patients and residual obstructive leaflets after valve ablation.

Materials and Methods

We retrospectively reviewed the medical records of 55 patients with PUV that was treated by the same surgeon between 2008 and 2012. Of these, 37 patients (67.3%) had no obstructive remnant leaflets (group A) and 18 patients (32.7%) had obstructive remnant leaflets (group B) in follow-up cystoscopy. Preoperative clinical and radiological findings were evaluated and compared between the groups.

Results

Among all the preoperative data we examined, the analysis revealed that age at the time of surgery (median age: group A, 15 months; group B, 7 months; p=0.017), echogenicity of kidneys (p<0.05), presence of vesicoureteral reflux (p<0.05), and grade of reflux (p<0.05) were significantly different between the groups. Method of valve ablation, anterior-posterior diameters of the renal pelvis, renal cortical thickness, bladder wall thickening, and scarring on the dimercaptosuccinic acid scan showed no significant differences between the two groups.

Conclusions

In our patients, younger age at surgery time, hyperechogenicity of renal parenchyma, presence of vesicoureteral reflux, and grade 4 or 5 reflux before surgery had a significant relationship with residual valves. More studies may result in enhanced management of patients at high risk of residual valves after PUV ablation, because the sooner the obstruction is resolved entirely, the better the outcome.

Changes in bladder wall thickness and detrusor wall thickness after surgical treatment of benign prostatic enlargement in patients with lower urinary tract symptoms: a preliminary report

PURPOSE

The purpose of the present study was to evaluate the perioperative changes in bladder wall thickness and detrusor wall thickness after transurethral prostatectomy.

MATERIALS AND METHODS

Fifty-one men who were treated for benign prostatic hyperplasia/lower urinary tract symptoms with transurethral prostatectomy were prospectively analyzed from May 2012 to July 2013. Prostate size, detrusor wall thickness, and bladder wall thickness were assessed by transrectal and transabdominal ultrasonography perioperatively. All postoperative evaluations were performed 1 month after the surgery.

RESULTS

The patients' mean age was 69.0 years, the mean prostate-specific antigen concentration was 8.1 ng/mL, and the mean prostate volume was 63.2 mL. The mean bladder wall thickness was 5.1 mm (standard deviation [SD], ±1.6), 5.1 mm (SD, ±1.6), and 5.0 mm (SD, ±1.4) preoperatively and 4.5 mm (SD, ±1.5), 4.5 mm (SD, ±1.3), and 4.6 mm (SD, ±1.2) postoperatively in the anterior wall, dome, and trigone, respectively (p=0.178, p=0.086, and p=0.339, respectively). The mean detrusor wall thickness was 0.9 mm (SD, ±0.4) preoperatively and 0.7 mm (SD, ±0.3) postoperatively (p=0.001). A subgroup analysis stratifying patients into a large prostate group (weight, ≥45 g) and a high Abrams-Griffiths number group (>30) showed a significant decrease in detrusor wall thickness (p=0.002, p=0.018).

CONCLUSIONS

There was a decrease in detrusor wall thickness after transurethral prostatectomy. The large prostate group and the high Abrams-Griffiths number group showed a significant decrease in detrusor wall thickness after surgery.

Adhesion molecules of detrusor muscle cells are influenced by a hypercholesterolemic diet or bladder outlet obstruction in a Wistar rat model

Background

Cell adhesion molecules (CAMs) are essential for maintaining tissue integrity by regulating intercellular and cell to extracellular matrix interactions. Cadherins and catenins are CAMs that are located on the cell membrane and are important for adherens junction (AJ) function. This study aims to verify if hypercholesterolemic diet (HCD) or bladder outlet obstruction (BOO) promotes structural bladder wall modifications specific to alterations in the expression of cadherins and catenins in detrusor muscle cells.

Methods

Forty-five 4-week-old female Wistar rats were divided into the following three groups: group 1 was a control group that was fed a normal diet (ND); group 2 was the BOO model and was fed a ND; and group 3 was a control group that was fed a HCD (1.25% cholesterol). Initially, serum cholesterol, LDL cholesterol and body weight were determined. Four weeks later, groups 1 and 3 underwent a sham operation; whereas group 2 underwent a partial BOO procedure that included a suture tied around the urethra. Six weeks later, all rats had their bladders removed, and previous exams were repeated. The expression levels of N-, P-, and E-cadherin, cadherin-11 and alpha-, beta- and gamma-catenins were evaluated by immunohistochemistry with a semiquantitative analysis.

Results

Wistar rats fed a HCD (group 3) exhibited a significant increase in LDL cholesterol levels (p=0.041) and body weight (p=0.017) when compared to both groups that were fed a normal diet in a ten-week period. We found higher β- and γ-catenin expression in groups 2 and 3 when compared to group 1 (p = 0.042 and p = 0.044, respectively). We also observed Cadherin-11 overexpression in group 3 when compared to groups 1 and 2 (p = 0.002).

Conclusions

A HCD in Wistar rats promoted, in addition to higher body weight gain and increased serum LDL cholesterol levels, overexpression of β- and γ-catenin in the detrusor muscle cells. Similar finding was observed in the BOO group. Higher Cadherin-11 expression was observed only in the HCD-treated rats. These findings may be associated with bladder dysfunctions that occur under such situations.

Cystometric parameters and the activity of signaling proteins in association with the compensation or decompensation of bladder function in an animal experimental model of partial bladder outlet obstruction

We conducted this study to determine whether the degree of detrusor contractility is associated with the compensation or decompensation of bladder function depending on the residual volume (RV) during the first two weeks after the onset of partial bladder outlet obstruction (BOO). Moreover, we also examined whether the degree of the phosphorylation and expression of signaling proteins [AMP-activated kinase (AMPK), extracellular signal‑regulated protein kinases 1 and 2 (ERK1/2) and protein kinase C (PKC)] is associated with the prevalence of compensation or decompensation of bladder function. Twenty-seven female Sprague-Dawley (SD) rats were randomly assigned to either the sham-operated group (n=7) or the group with partial bladder outlet obstruction (BOO) (n=20). We then measured cystometric parameters from three reproducible micturition cycles and averaged the results for a comparison between the two groups. Based on a cut-off value of a mean RV% of 25%, we subdivided our experimental animals into two subgroups: the subgroup with bladder compensation (mean RV%, <25%) and the subgroup with bladder decompensation (mean RV%, >25%). Our results indicated that the degree of detrusor overactivity (DO) was associated with the compensation or decompensation of bladder function depending on the RV during the first two weeks after the onset of BOO in an animal experimental model of partial BOO. Moreover, we also demonstrate that AMPK and ERK1/2 are involved in the compensation or decompensation of bladder function. Furthermore, our results suggest that PKC is not involved in two-phase bladder contraction. Alterations in the activities of signaling proteins, such as AMPK and ERK1/2 may prove to be helpful in the treatment of patients with voiding difficulty.

Efficacy of Additional Dutasteride on Lower Urinary Tract Symptoms in Patients with Alpha-1 Blocker-Resistant Benign Prostatic Hyperplasia

OBJECTIVE

We investigated the effects of dutasteride on urination and quality of life (QOL) in patients diagnosed with benign prostatic hyperplasia (BPH) who showed poor improvement in lower urinary tract symptoms (LUTS) with alpha-1 blockers.

METHODS

We retrospectively analyzed 108 patients with BPH who took dutasteride for more than 3 months from October 2009 to October 2011. The patients showed poor improvement in LUTS despite administration of alpha-1 blockers for more than 3 months; all had an International Prostate Symptom Score (IPSS) of eight or greater. We investigated changes in prostate-specific antigen and prostate volume and performed uroflowmetry and medical interviews to assess IPSS-QOL score and BPH impact index (BII).

RESULTS

Mean prostate volume was 52.8 ± 22.2 mL, and the mean period of dutasteride administration was 284 ± 118 days. Prostate volume decreased 24.1% from baseline to 6 months after administration. Voiding symptoms and storage symptoms showed improvements with longer administration periods, but only nocturia showed no clear improvement. There was a 0.9-point decrease in BII after 6 months. There was no statistically significant association between the rate of prostate volume reduction and improvement in voiding and storage symptoms.

CONCLUSION

Additional administration of dutasteride to patients with alpha-1 blocker-resistant BPH led to improvements in all voiding and storage symptoms except nocturia, and showed no correlation between the prostate volume reduction rates and improvement in LUTS.

Further evidence of endogenous hydrogen sulphide as a mediator of relaxation in human and rat bladder

We investigated the expression of hydrogen sulphide (H2S) in human and rat lower urinary tract (including bladder, prostate and urethra) tissues, and we sought to determine whether H2S induces relaxation of human and Sprague-Dawley (SD) rat bladder strips. Human normal lower urinary tract tissue was obtained for the evaluation of endogenous H2S productivity using a sulphide-sensitive electrode and for the analysis of the expression levels of all three synthases of endogenous H2S, cystathionine β-synthase (CBS), cystathionine γ lyase (CSE) and 3-mercaptopyruvate sulphur transferase (MPST, as known as 3-MST) by Western blot assay. CBS, CSE and MPST were located in human sample slides by immunohistochemistry. Human and male adult SD rat bladder strips were tested for H2S function with a transducer and recorded. All experiments were repeated six times. The endogenous H2S productivity and the H2S synthases had various distributions in the human and rat lower urinary tract tissues and were located in both epithelial and stromal sections. L-cysteine (L-Cys, a substrate of CBS, CSE and MPST) elicited relaxation in a dose-dependent manner on human bladder strips pre-contracted by acetylcholine chloride. This effect could be diminished by the ATP-sensitive potassium ion (KATP) channel blocker glibenclamide (GLB), the CSE inhibitor DL-propargylglycine (PPG) and the CBS inhibitor hydroxylamine (HA). H2S and its three synthases were present in the human and rat lower urinary tract tissues and relaxed human and rat bladder strips, which implied that endogenous H2S might play a role in physiological function and pathological disorders of the lower urinary tract symptoms (LUTS) or overactive bladder (OAB).

Future direction in pharmacotherapy for non-neurogenic male lower urinary tract symptoms

BACKGROUND

The pathophysiology of male lower urinary tract symptoms (LUTS) is highly complex and multifactorial. The shift in perception that LUTS are not sex or organ specific has not been followed by significant innovations regarding the available drug classes.

OBJECTIVE

To review pathophysiologic mechanisms and clinical and experimental data related to the development of new pharmacologic treatments for male LUTS.

EVIDENCE ACQUISITION

The PubMed database was used to identify articles describing experimental and clinical studies of pathophysiologic mechanisms contributing to male LUTS and, supported by them, new pharmacotherapies with clinical or experimental evidence in the field.

EVIDENCE SYNTHESIS

Several pathologic processes (eg, androgen signaling, inflammation, and metabolic factors) and targets (eg, the urothelium, prostate, interstitial cells, detrusor, neurotransmitters, neuromodulators, and receptors) have been implicated in male LUTS. Some newly introduced drugs, such as phosphodiesterase type 5 inhibitors and β3-adrenergic agonists, have just started broad use in clinical practice. Drugs with potential benefit, such as vitamin D3 receptor analogs, gonadotropin-releasing hormone antagonists, cannabinoids, and drugs injected into the prostate, have been evaluated in experimental studies and have progressed to clinical trials. However, safety and efficacy data for these drugs are still scarce. Some compounds with interesting profiles have only been tested in experimental settings (eg, transient receptor potential channel blockers, Rho-kinase inhibitors, purinergic receptor blockers, and endothelin-converting enzyme inhibitors).

CONCLUSIONS

New pathophysiologic mechanisms of male LUTS are described that lead to the continuous development of new pharmacotherapies. To date, few drugs have been added to the current armamentarium, and several are in various phases of clinical or experimental investigation.

Different muscarinic receptor subtypes modulate proliferation of primary human detrusor smooth muscle cells via Akt/PI3K and map kinases

While acetylcholine (ACh) and muscarinic receptors in the bladder are mainly known for their role in the regulation of smooth muscle contractility, in other tissues they are involved in tissue remodelling and promote cell growth and proliferation. In the present study we have used primary cultures of human detrusor smooth muscle cells (HDSMCs), in order to investigate the role of muscarinic receptors in HDSMC proliferation. Samples were obtained as discarded tissue from men >65 years undergoing radical cystectomy for bladder cancer and cut in pieces that were either immediately frozen or placed in culture medium for the cell culture establishment. HDSMCs were isolated from samples, propagated and maintained in culture. [(3)H]-QNB radioligand binding on biopsies revealed the presence of muscarinic receptors, with a Kd of 0.10±0.02nM and a Bmax of 72.8±0.1fmol/mg protein. The relative expression of muscarinic receptor subtypes, based on Q-RT-PCR, was similar in biopsies and HDSMC with a rank order of M2≥M3>M1>M4>M5. The cholinergic agonist carbachol (CCh, 1-100μM) concentration-dependently increased [(3)H]-thymidine incorporation (up to 46±4%). This was concentration-dependently inhibited by the general muscarinic receptor antagonist atropine and by subtype-preferring antagonists with an order of potency of darifenacin >4-DAMP>AF-DX 116. The CCh-induced cell proliferation was blocked by selective PI-3 kinase and ERK activation inhibitors, strongly suggesting that these intracellular pathways mediate, at least in part, the muscarinic receptor-mediated cell proliferation. This work shows that M2 and M3 receptors can mediate not only HDSM contraction but also proliferation; they may also contribute bladder remodelling including detrusor hypertrophy.

Effect of Transurethral Resection of the Prostate on Storage Symptoms in Patients with Benign Prostatic Hyperplasia of Less than 30 ml

Purpose

Many patients with benign prostatic hyperplasia (BPH) have not only voiding symptoms but also storage symptoms. Despite the many types of treatment that have been developed for BPH, storage symptoms persist. We conducted an assessment of the efficacy of transurethral resection of the prostate (TURP) and the change in the International Prostate Symptoms Score (IPSS) storage sub-score after the procedure according to prostate size in patients with BPH.

Materials and Methods

Men aged 50 years or older who had BPH were enrolled in this study. 186 patients were divided into two groups according to prostate size measuring using transrectal ultrasonography: In group 1, prostate size was less than 30 ml (51 patients), and in group 2, prostate size was greater than 30 ml (135 patients). All of the patients underwent TURP. We examined whether the degree of change in the IPSS, voiding symptoms, storage symptoms, and quality of life (QoL) differed before and after TURP and according to prostate size.

Results

After three months of TURP, the subjects in both groups showed significant improvement in the IPSS, voiding symptoms, storage symptoms, QoL, and maximum flow rate (p<0.05). The scores for the IPSS, voiding symptoms, storage symptoms, and QoL of group 1 and 2 after three months of TURP were 16.36, 14.25 (p=0.233), 8.21, 8.24 (p=0.980), 8.11, 5.16 (p=0.014), 2.89, and 2.10 (p=0.030), respectively.

Conclusions

TURP is an effective treatment for patients with BPH, regardless of prostate size. However, while the improvement in the storage symptoms of patients with a prostate size of less than 30 ml was not significant, it was in patients with a prostate size greater than 30 ml.

Remodeling of the muscle layer (detrusor muscle) of hyperactive bladder disease in patients with benign prostatic hyperplasia

We studied remodeling of the detrusor of hyperactive bladder in patients with benign prostatic hyperplasia. Detrusor remodeling was caused by degenerative and atrophic changes and elimination of smooth muscle cells, compensatory hypertrophy of remaining cells, and diffuse or focal-diffuse replacement fibrosis. Focal or diffuse infiltration of all layers of the detrusor with lymphocytes and plasma cells is an important pathologic feature of hyperactive bladder. These changes correlated with pronounced remodeling of the glandular and fibrotic-muscular layers in the prostate gland. We have identified stereotyped patterns of the intracellular reorganization of smooth muscle cells in the detrusor of hyperactive bladder and in the prostate with benign prostatic hyperplasia, which represent both the compensatory and adaptive reactions (hypertrophied cells with minor ultrastructural changes) and the types of smooth muscle cell injury ("dark" electron-dense cells and "light" cells with pronounced lysis of myofilaments and discomplexation of organelles).

Benign prostatic hyperplasia

Male Lower Urinary Tract symptoms (LUTs) and Benign Prostatic Hyperplasia (BPH) provide a significant proportion of the core urologists workload, and will continue to do so for the foreseeable future with an increasingly elderly population. This review sets out to provide an overview of the current understanding around BPH and male LUTs as well as investigations and treatment options.

Bladder interstitial cells: an updated review of current knowledge

The field of bladder research has been energized by the study of novel interstitial cells (IC) over the last decade. Several subgroups of IC are located within the bladder wall and make structural interactions with nerves and smooth muscle, indicating integration with intercellular communication and key physiological functions. Significant progress has been made in the study of bladder ICs' cellular markers, ion channels and receptor expression, electrical and calcium signalling, yet their specific functions in normal bladder filling and emptying remain elusive. There is increasing evidence that the distribution of IC is altered in bladder pathophysiologies suggesting that changes in IC may be linked with the development of bladder dysfunction. This article summarizes the current state of the art of our knowledge of IC in normal bladder and reviews the literature on IC in dysfunctional bladder.

[Predictive value of the penile cuff-test for the assessment of bladder outlet obstruction in men]

PURPOSE

To assess the diagnostic performances and the acceptability of the penile cuff test (PCT) which is a non invasive method for the evaluation of bladder outlet obstruction (BOO), in comparison with the pressure flow study (PFS), the actual gold-standard.

MATERIAL

Monocentric prospective study comparing the following subsets: "obstructed", "not obstructed" or "equivocal", deduced from PFS vs PCT, in 30 consecutive patients presenting with lower urinary tract symptoms. For the PCT, a cuff placed around the penis inflated automatically during the micturition, until flow rate interruption. The interruption cuff pressure revealed the isovolumetric bladder pressure (Pcuff-int). The data collected - Pcuff-int and maximum flow rate - were automatically reported on ICS modified nomogram.

RESULTS

With the PFS, 11 patients (39%) were classified "obstructed", six patients (22%) "non-obstructed" and 11 patients (39%) "equivocal". In 61% cases, the patient was classified in the same category by both techniques. The "obstructed positive predictive value" of the PCT was 82% and the "non-obstructed-equivocal negative predictive value" was 88%. The median acceptability visual analogic scale score was 1/10 (0-3) for the PCT whereas it was 5/10 (2-10) for the PFS. This difference was statistically significant (p=0.004).

CONCLUSION

The PCT was a reliable non-invasive tool for the diagnosis of BOO in male, in comparison with PFS. The predictive values of the PCT were relevant and its tolerance was better than PFS.

Differential expression of class I small leucine-rich proteoglycans in an animal model of partial bladder outlet obstruction

PURPOSE

Partial bladder outlet obstruction has been shown in a rat model to progress from inflammation to hypertrophy to fibrosis. Small leucine-rich proteoglycans are extracellular matrix components associated with collagen fibrillogenesis and resultant scar formation. Two such critical small leucine-rich proteoglycans are decorin and biglycan. We hypothesized that in keeping with other scar models, decorin would be down-regulated and biglycan would be up-regulated with the onset of fibrosis compared to sham.

MATERIALS AND METHODS

We challenged our hypothesis with female Fisher rats that underwent ligation of the bladder neck or sham surgery. Animals were sacrificed at 4, 8 and 12 weeks, and bladders were harvested. Frozen sections were stained for immunofluorescence for decorin and biglycan. mRNA expression for decorin and biglycan was analyzed using quantitative reverse transcriptase polymerase chain reaction.

RESULTS

All rats survived to specified experimental end points in good health. Immunofluorescent stains showed progressive down-regulation of decorin and up-regulation of biglycan during the 12-week course by 0.36 and 1.82-fold, respectively (p = 0.02 and p = 0.02), compared to shams. Quantitative real-time reverse transcriptase polymerase chain reaction confirmed these findings in 12-week specimens, showing a down-regulation of decorin by a factor of 0.45 (p = 0.02) and up-regulation of biglycan by a factor of 2.04-fold (p = 0.08).

CONCLUSIONS

We present the first identification to our knowledge of small leucine-rich proteoglycans in normal and abnormal bladder tissue, and their differential expression in the process of bladder fibrosis, consistent with experimental findings in other anatomical sites. Further investigation into small leucine-rich proteoglycan expression and regulation may allow for the development of new antifibrotic therapeutics.

Effect of prostatitis on lower urinary tract symptoms: retrospective analysis of prostate biopsy tissue

Purpose

Most patients, even some urologists, assume that prostate volume is the most important prognostic factor for lower urinary tract symptoms (LUTS). In some cases, however, prostatic inflammation is a more important factor in LUTS than is prostate volume. For this reason, comparison of the impact on LUTS of inflammation and prostate volume is an attractive issue.

Materials and Methods

From January 2000 to May 2009, 1,065 men aged between 47 and 91 years (who underwent transrectal ultrasound-guided prostate needle biopsy and transurethral prostatectomy) were retrospectively investigated. Components such as age, serum prostate-specific antigen (PSA) level, prostate volume, and the presence of prostatitis were investigated through independent-sample t-tests, chi-square tests, and univariate and multivariate analyses.

Results

Chi-square tests between prostatitis, prostate volume, serum PSA, and severe LUTS showed that prostate volume (R=0.173; p=0.041) and prostatitis (R=0.148; p<0.001) were related to LUTS. In particular, for a prostate volume under 50 ml, prostatitis was a stronger risk factor than was prostate volume. Among the multivariate predictors, prostatitis (odds ratio [OR]: 1.945; p<0.001) and prostate volume (OR, 1.029; p<0.001) were found to be aggravating factors of LUTS.

Conclusions

For patients with prostate volume less than 50 ml, prostatitis was found to be a more vulnerable factor for LUTS. For those with prostate volume over 50 ml, on the other hand, the volume itself was a more significant risk factor than was prostatitis. In conclusion, the presence of prostatitis is one of the risk factors for LUTS with increased prostate volume.

Bladder mechanoreceptor changes after artificial bladder outlet obstruction in the anesthetized rat

AIMS

Experimental animal models of bladder outlet obstruction (BOO) have reproduced several features of BOO in man, i.e., detrusor hypertrophy, instability, frequency, and residual urine. This study was focused on the mechanisms underlying the development of residual urine in patient with benign prostatic hyperplasia (BPH) by examining changes in tension sensitivity of bladder mechanoreceptors in rat model.

METHODS

Female adult Sprague-Dawley rats including 12 BOO and 17 sham operated rats were used in this study. Cystometrograms together with the bladder afferent activity were recorded. Tension sensitivity of the afferents was determined by plotting the normalized afferent response against the contraction evoked bladder pressure at different volumes. Degree of obstruction was assessed by the wet weight of the bladder at the end of the experiment.

RESULTS

The bladder weight, maximal bladder capacity, micturition threshold volume, peak contraction force, and volume at peak contraction force were all significantly increased in obstructed animals. The threshold volume for afferent activation was increased (mean 0.60 ml compared to 0.15 ml in controls; P < 0.001), positively correlated with the bladder weight (r = 0.74). The tension sensitivity of the bladder mechanoreceptors and the slope of their normalized pressure-response functions were significantly lower at the comparable volumes in the obstructed animals.

CONCLUSIONS

Rats with BOO had bladder mechanoreceptors with higher threshold volumes and lower tension sensitivity. Such changes would result in a weaker afferent drive of the micturition reflex. Similar changes may contribute to the development of residual urine and retention in patients with BOO.

Therapeutic effects of connexin inhibitors on detrusor overactivity induced by bladder outlet obstruction in rats

OBJECTIVES

To investigate the alterations in Connexin 43 (Cx43) and connexin 26 (Cx26) levels in the bladder outlet obstruction (BOO)-induced detrusor overactivity and examine the effect of connexin inhibitors on this condition.

METHODS

Fifty Sprague-Dawley rats were divided into 4 groups: sham-operated control group (n = 10), BOO group (n = 10), and 2 groups that were administered connexin inhibitors. The first of these 2 groups was administered 18β-glycyrrhetinic acid (BOO-18β-GA group, n = 15) and the second group was given oleamide (BOO-oleamide group, n = 15). Cystometrogram was performed in all groups after 2 weeks of obstruction. The expression levels of Cx26 and Cx43 were analyzed using immunohistochemical staining and Western blot.

RESULTS

The intercontraction interval was markedly shorter in the BOO group compared with the control group (P <.05). Intercontraction intervals in the BOO-18β-GA and BOO-oleamide groups at 2 weeks were significantly longer than that observed for the BOO group (P <.05). The expression of Cx43 and Cx26 were increased in the BOO group. After administration of connexin inhibitors, downregulation of Cx43 and Cx26 was noted.

CONCLUSIONS

These results suggest that upregulation of Cx43 and Cx26 induce detrusor overactivity after BOO, and connexin inhibitors may have some role in relieving BOO-induced detrusor overactivity in rats.

Effect of 5-alpha Reductase Inhibitor on Storage Symptoms in Patients with Benign Prostatic Hyperplasia

Purpose

Many patients with benign prostatic hyperplasia (BPH) have storage symptoms. The aim of this study was to evaluate the effects of treatment with a 5-alpha reductase inhibitor (5ARI) on storage symptoms in patients with BPH.

Methods

This study was conducted in 738 patients with lower urinary tract symptoms secondary to BPH. Patients with a prostate volume of higher than 30 mL on the transrectal ultrasound were classified into two groups: group A, in which an alpha blocker was solely administered for at least 12 months, and group B, in which a combination treatment regimen of an alpha blocker plus 5ARI was used. This was followed by an analysis of the changes in parameters such as the total International Prostate Symptom Score (IPSS), voiding symptom subscore, and storage symptom subscore between the two groups. In addition, we examined whether there was a significant difference between the two groups in the degree of change in storage symptoms between before and after the pharmacological treatment.

Results

Of the 738 men, 331 had a prostate volume ≥30 mL, including 150 patients in group A and 181 patients in group B. Total IPSS, the voiding symptom subscore, and the storage symptom subscore were significantly lower after treatment than before treatment in both groups (P<0.05). A comparison of the degree of change between before and after treatment, however, showed no significant differences in the storage symptom subscore between the two groups (P>0.05).

Conclusions

Alpha blocker and 5ARI combination treatment is effective for patients with BPH including storage symptoms. However, 5ARI does not exert a significant effect on storage symptoms in BPH patients.

Models of inflammation of the lower urinary tract

Inflammation of the lower urinary tract occurs frequently in people. The causes remain obscure, with the exception of urinary tract infection. Animal models have proven useful for investigating and assessing mechanisms underlying symptoms associated with lower urinary tract inflammation and options for suppressing these symptoms. This review will discuss various animal models of lower urinary tract inflammation, including feline spontaneous (interstitial) cystitis, neurogenic cystitis, autoimmune cystitis, cystitis induced by intravesical instillation of chemicals or bacterial products (particularly lipopolysaccharide or LPS), and prostatic inflammation initiated by transurethral instillation of bacteria. Animal models will continue to be of significant value in identifying mechanisms resulting in bladder inflammation, but the relevance of some of these models to the causes underlying clinical disease is unclear. This is primarily because of the lack of understanding of causes of these disorders in people. Comparative and translational studies are required if the full potential of findings obtained with animal models to improve prevention and treatment of lower urinary tract inflammation in people is to be realized.

Effects of mechanical stretch on interstitial cells of Cajal in guinea pig bladder

OBJECTIVES

C-kit positive interstitial cells of Cajal (ICCs) play an important role in the regulation of the smooth muscle motility. In this study, we investigated the mechanical sensitivity of ICCs in guinea pig bladder and their possible relationship with detrusor overactivity (DO).

METHODS

Stretch load was performed in vivo in DO models produced by 4 wk of partial bladder outlet obstruction (PBOO). Number and morphology of ICCs were examined using a specific ICC marker, c-kit, immunochemistry staining. The spontaneous and stretch-induced calcium transients (SICT) of ICCs were investigated in cells cultured onto flexible silicone membranes preloaded with the Ca(2+) indicator fluo-4AM in vitro.

RESULTS

C-kit positive ICCs were mainly located along and between bladder smooth muscle bundles. ICCs in DO bladders displayed more lateral branching with mutual connections. The number of c-kit positive bladder ICCs was increased in the DO group compared with the control group (n = 50, P < 0.05). Cultured ICCs from DO bladders showed spontaneous calcium waves with higher frequency and lower amplitude than those from control bladders (n = 15, P < 0.05). Significant SICT were detected in cultured bladder ICCs. SICT generated in ICCs from DO were more likely to transfer to adjacent smooth muscle cells through cell membrane connection than ICCs from control bladders.

CONCLUSIONS

Long-term overload tension following PBOO caused changes in morphology, quantity and spontaneous calcium transients of ICCs in guinea pig bladder. Mechanical sensitivity and interaction with SMC of ICCs may contribute to the mechanosensitive conductances in bladder regulation, and may play a role in the pathogenesis of DO.

Non-invasive parameters predicting bladder outlet obstruction in Korean men with lower urinary tract symptoms

The goal of this study was to evaluate the clinical and urodynamic features in Korean men with lower urinary tract symptoms (LUTS) and to determine non-invasive parameters for predicting bladder outlet obstruction (BOO). Four hundred twenty nine Korean men with LUTS over 50 yr of age underwent clinical evaluations for LUTS including urodynamic study. The patients were divided into two groups according to the presence of BOO. These two groups were compared with regard to age, the results of the uroflowmetry, serum prostate-specific antigen (PSA) level, prostate volume, International Prostate Symptom Score (I-PSS), and the results of the urodynamic study. Patients with BOO had a lower maximal flow rate (Q(max)), lower voided volume, higher serum PSA level and larger prostate volume (P<0.05). BOO group had a significantly higher rate of involuntary detrusor contraction and poor compliance compared to the patients without BOO (P<0.05). The multivariate analysis showed that Q(max) and poor compliance were significant factors for predicting BOO. Our results show that Q(max) plays a significant role in predicting BOO in Korean men with LUTS. In addition, BOO is significantly associated with detrusor dysfunction, therefore, secondary bladder dysfunction must be emphasized in the management of male patients with LUTS.