Ureteral urine transport: changes in bolus volume, peristaltic frequency, intraluminal pressure and volume of flow resulting from autonomic drugs

Activation of Piezo1 or TRPV2 channels inhibits human ureteral contractions via NO release from the mucosa

We aimed to investigate the expression and motor modulatory roles of several mechano-sensitive channels (MSCs) in human ureter. Human proximal ureters were obtained from eighty patients subjected to nephrectomy. Expression of MSCs at mRNA, protein and functional levels were examined. Contractions of longitudinal ureter strips were recorded in organ bath. A fluorescent probe Diaminofluoresceins was used to measure nitric oxide (NO). RT-PCR analyses revealed predominant expression of Piezo1 and TRPV2 mRNA in intact ureter and mucosa. Immunofluorescence assays indicate proteins of MSCs (Piezo1/Piezo2, TRPV2 and TRPV4) were mainly distributed in the urothelium. Ca2+ imaging confirmed functional expression of TRPV2, TRPV4 and Piezo1 in cultured urothelial cells. Specific agonists of Piezo1 (Yoda1, 3-300 μM) and TRPV2 (cannabidiol, 3-300 μM) attenuated the frequency of ureteral contractions in a dose-dependent manner while the TRPV4 agonist GSK1016790A (100 nM-1 μM) exerted no effect. The inhibitory effects of Piezo1 and TRPV2 agonists were significantly blocked by the selective antagonists (Dooku 1 for Piezo1, Tranilast for TRPV2), removal of the mucosa, and pretreatment with NO synthase inhibitor L-NAME (10 μM). Yoda1 (30 μM) and cannabidiol (50 μM) increased production of NO in cultured urothelial cells. Our results suggest that activation of Piezo1 or TRPV2 evokes NO production and release from mucosa that may mediate mechanical stimulus-induced reduction of ureter contractions. Our findings support the idea that targeting Piezo1 and TRPV2 channels may be a promising pharmacological strategy for ureter stone passage or colic pain relief.

The modulation of ureteral smooth muscle contractile responses by α1- and α2-adrenoceptor activation

PURPOSE

This study was performed to investigate the influence of α-adrenoceptor subtypes upon ureteral smooth muscle contractile responses.

METHODS

Rat ureters were challenged in vitro with noradrenaline (NA), the α₁-adrenoceptor agonist phenylephrine (PE), and the α₂-adrenoceptor agonist clonidine (CLON). The influences of the agonists on the magnitude and frequency of acetylcholine (ACh)-stimulated phasic contractile responses were recorded.

RESULTS

The magnitude of the phasic contractile responses effected by ACh was not significantly influenced by the adrenoceptor agonists, but the frequency of the response was significantly enhanced by all three agonists (p < 0.05). Idazoxan and prazosin abolished the rise in frequency effected by CLON and PE, respectively, whereas both antagonists in combination were required to abolish the increase in frequency effected by NA.

CONCLUSIONS

It has been demonstrated that α₁- and α₂-adrenoceptors modulate the contractile function of rat ureteral smooth muscle by increasing the frequency, but not the magnitude, of phasic contractile responses. The enhancement of contractile function by NA is mediated by mechanisms dependent upon both α₁- and α₂-adrenoceptors.

Alpha-blockers as medical expulsive therapy for ureteral stones

BACKGROUND

Ureteral colic is a common reason for patients to seek medical care. Alpha-blockers are commonly used to improve stone passage through so-called medical expulsive therapy (MET), but their effectiveness remains controversial. This is an update of a 2014 Cochrane review; since that time, several large randomised controlled trials (RCTs) have been reported, making this update relevant.

OBJECTIVES

To assess effects of alpha-blockers compared with standard therapy for ureteral stones 1 cm or smaller confirmed by imaging in adult patients presenting with symptoms of ureteral stone disease.

SEARCH METHODS

On 18 November 2017, we searched CENTRAL, MEDLINE Ovid, and Embase. We also searched ClinicalTrials.gov and the WHO Portal/ICTRP to identify all published/unpublished and ongoing trials. We checked all references of included and review articles and conference proceedings for articles relevant to this review. We sent letters to investigators to request information about unpublished or incomplete studies.

SELECTION CRITERIA

We included RCTs of ureteral stone passage in adult patients that compared alpha-blockers versus standard therapy.

DATA COLLECTION AND ANALYSIS

Two review authors screened studies for inclusion and extracted data using standard methodological procedures. We performed meta-analysis using a random-effects model. Primary outcomes were stone clearance and major adverse events; secondary outcomes were stone expulsion time, number of pain episodes, use of diclofenac, hospitalisation, and surgical intervention. We assessed the quality of evidence on a per-outcome basis using the GRADE approach.

MAIN RESULTS

We included 67 studies with 10,509 participants overall. Of these, 15 studies with 5787 participants used a placebo.Stone clearance: Based on the overall analysis, treatment with an alpha-blocker may result in a large increase in stone clearance (risk ratio (RR) 1.45, 95% confidence interval (CI) 1.36 to 1.55; low-quality evidence). A subset of higher-quality, placebo-controlled trials suggest that the likely effect is probably smaller (RR 1.16, 95% CI 1.07 to 1.25; moderate-quality evidence), corresponding to 116 more (95% CI 51 more to 182 more) stone clearances per 1000 participants.Major adverse events: Based on the overall analysis, treatment with an alpha-blocker may have little effect on major adverse events (RR 1.25, 95% CI 0.80 to 1.96; low-quality evidence). A subset of higher-quality, placebo-controlled trials suggest that alpha-blockers likely increase the risk of major adverse events slightly (RR 2.09, 95% CI 1.13 to 3.86), corresponding to 29 more (95% CI 3 more to 75 more) major adverse events per 1000 participants.Patients treated with alpha-blockers may experience shorter stone expulsion times (mean difference (MD) -3.40 days, 95% CI -4.17 to -2.63; low-quality evidence), may use less diclofenac (MD -82.41, 95% CI -122.51 to -42.31; low-quality evidence), and likely require fewer hospitalisations (RR 0.51, 95% CI 0.34 to 0.77; moderate-quality evidence), corresponding to 69 fewer hospitalisations (95% CI 93 fewer to 32 fewer) per 1000 participants. Meanwhile, the need for surgical intervention appears similar (RR 0.74, 95% CI 0.53 to 1.02; low-quality evidence), corresponding to 28 fewer surgical interventions (95% CI 51 fewer to 2 more) per 1000 participants.A predefined subgroup analysis (test for subgroup differences; P = 0.002) suggests that effects of alpha-blockers may vary with stone size, with RR of 1.06 (95% CI 0.98 to 1.15; P = 0.16; I² = 62%) for stones 5 mm or smaller versus 1.45 (95% CI 1.22 to 1.72; P < 0.0001; I² = 59%) for stones larger than 5 mm. We found no evidence suggesting possible subgroup effects based on stone location or alpha-blocker type.

AUTHORS' CONCLUSIONS

For patients with ureteral stones, alpha-blockers likely increase stone clearance but probably also slightly increase the risk of major adverse events. Subgroup analyses suggest that alpha-blockers may be less effective for smaller (5 mm or smaller) than for larger stones (greater than 5 mm).

Formation of struvite urinary stones and approaches towards the inhibition-A review

BACKGROUND

Struvite is one of the most common urinary/kidney stones, composed of magnesium ammonium phosphate (MgNHPO₄·H₂O). They are also termed as infection stones as these are associated with urinary tract infections. Numerous studies have been carried out to examine the growth and inhibition of struvite stones.

OBJECTIVE

This review summarizes various reports on the factors responsible for inducing struvite stones in the kidney and gives a detailed account of studies on inhibition of growth of struvite crystals.

RESULTS

The presence of urea-splitting bacteria such as Proteus mirabilis and alkaline pH plays a crucial role in struvite formation. In vitro inhibition of struvite stones by various chemical agents were examined mainly in artificial urine whereas inhibition by herbal extracts was studied in vitro by gel diffusion technique. Herbal extracts of curcumin, Boerhaavia diffusa Linn, Rotula aquatica and many other plants, as well as some chemicals like pyrophosphate, acetohydroxamic acid, disodium EDTA and trisodium citrate, were reported to successfully inhibit struvite formation.

CONCLUSION

The present review recapitulates various factors affecting the growth of struvite urinary stones and the inhibitory role of certain chemicals and herbal extracts. Most of the tested plants are edible hence can be easily consumed without any adverse effects whereas the side effects of chemicals are unknown due to lack of toxicity studies. Thus, the use of herbal extracts might serve as an alternate and safe therapy for prevention of struvite stones.

Efficacy and Safety of Tamsulosin in Medical Expulsive Therapy for Distal Ureteral Stones with Renal Colic: A Multicenter, Randomized, Double-blind, Placebo-controlled Trial

BACKGROUND

Recent large high-quality trials have questioned the clinical effectiveness of medical expulsive therapy using tamsulosin for ureteral stones.

OBJECTIVE

To evaluate the efficacy and safety of tamsulosin for distal ureteral stones compared with placebo.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a double-blind, placebo-controlled study of 3296 patients with distal ureteral stones, across 30 centers, to evaluate the efficacy and safety of tamsulosin.

INTERVENTION

Participants were randomly assigned (1:1) into tamsulosin (0.4mg) or placebo groups for 4 wk.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary end point of analysis was the overall stone expulsion rate, defined as stone expulsion, confirmed by negative findings on computed tomography, over a 28-d surveillance period. Secondary end points included time to stone expulsion, use of analgesics, and incidence of adverse events.

RESULTS AND LIMITATIONS

Among 3450 patients randomized between September 1, 2011, and August 31, 2013, 3296 (96%) were included in the primary analysis. Tamsulosin benefits from a higher stone expulsion rate than the placebo (86% vs 79%; p<0.001) for distal ureteral stones. Subgroup analysis identified a specific benefit of tamsulosin for the treatment of large distal ureteral stones (>5mm). Considering the secondary end points, tamsulosin-treated patients reported a shorter time to expulsion (p<0.001), required lower use of analgesics compared with placebo (p<0.001), and significantly relieved renal colic (p<0.001). No differences in the incidence of adverse events were identified between the two groups.

CONCLUSIONS

Our data suggest that tamsulosin use benefits distal ureteral stones in facilitating stone passage and relieving renal colic. Subgroup analyses find that tamsulosin provides a superior expulsion rate for stones >5mm, but no effect for stones ≤5mm.

PATIENT SUMMARY

In this report, we looked at the efficacy and safety of tamsulosin for the treatment of distal ureteral stones. We find that tamsulosin significantly facilitates the passage of distal ureteral stones and relieves renal colic.

Medical expulsive therapy for ureteric stones: Analysing the evidence from systematic reviews and meta-analysis of powered double-blinded randomised controlled trials

Objective

To conduct a systematic review and meta-analysis investigating the efficacy and safety of medical expulsive therapy (MET) in low risk of bias (RoB) randomised controlled trials (RCTs).

Methods

A Cochrane style systematic review was conducted on published literature from 1990 to 2016, to include low RoB and a power calculation. A pooled meta-analysis was conducted.

Results

The MET group included 1387 vs 1381 patients in the control group. The analysis reveals α-blockers increased stone expulsion rates (78% vs 74%) (P < 0.001), whilst calcium channel blockers (CCBs) had no effect compared to controls (79% vs 75%) (P = 0.38). In the subgroup analysis, α-blockers had a shorter time to stone expulsion vs the control group (P < 0.001). There were no significant differences in expulsion rates between the treatment groups and control group for stones <5 mm in size (P = 0.48), proximal or mid-ureteric stones (P = 0.63 and P = 0.22, respectively). However, α-blockers increased stone expulsion in stones >5 mm (P = 0.02), as well as distal ureteric stones (P < 0.001). The α-blocker group developed more side-effects (6.6% of patients; P < 0.001). The numbers needed to treat for α-blockers was one in 14, for stones >5 mm one in eight, and for distal stones one in 10.

Conclusion

The primary findings show a small overall benefit for α-blockers as MET for ureteric stones but no benefit with CCBs. α-blockers show a greater benefit for large (>5 mm) ureteric stones and those located in the distal ureter, but no benefit for smaller or more proximal stones. α-blockers are associated with a greater risk of side-effects compared to placebo or CCBs.

Alpha blockers in the management of ureteric lithiasis: A meta-analysis

INTRODUCTION

Effective medical expulsion for ureteric stones with α-blockers offers numerous advantages over surgical alternatives. However, its effectiveness remains uncertain and with the publication of new trial data, the available evidence requires reappraisal.

OBJECTIVE

The aim of this study was to assess the efficacy of α-blockers the management of ureteric lithiasis.

METHODS

A systematic review of the literature, with predefined search criteria, was conducted using PubMed and Embase. All randomised trials comparing α-blocker monotherapy to placebo or standard therapy were included. Stone expulsion rate was the primary outcome measure. Secondary outcome measures were time to stone expulsion, analgesic usage and pain scores. Subgroup analyses assessed individual adrenergic antagonists and variations in standard therapy. Sensitivity analysis was based on stone location, stone size, Cochrane Risk of Bias score and study protocol. Summary effects were calculated using a random-effect model and presented as Relative risks (RR) and mean differences (MD) for dichotomous and continuous outcome measures, respectively.

RESULTS

Sixty-seven studies randomising 6654 patients were included in the meta-analysis. Stone expulsion rates improved with α-blockers (RR, 1.49; 95% CI 1.38-1.61). Contrast enhanced funnel showed evidence of publication bias. Stone expulsion time was 3.99 days (CI -4.75 to -3.23) shorter with α-blockers. Similarly, patients required 106.53 mg [CI -148.20 to -64.86] less diclofenac compared with control/placebo, and had 0.80 [CI -1.07 to -0.54] fewer pain episodes. Visual Analogue Scores were also reduced, -2.43 [CI -3.87 to -0.99]. All formulations of α-antagonists all demonstrated beneficial effects over conservative treatment/placebo. Sensitivity analysis demonstrated significant effects of stone location, stone size and study design.

CONCLUSIONS AND RELEVANCE

Despite the opposing results of recently published trial, current evidence continues to demonstrate a potential benefit of α-blocker treatment particularly for distal stones over 5 mm.

Pathophysiological aspects of ureterorenoscopic management of upper urinary tract calculi

PURPOSE OF REVIEW

Indications for ureterorenoscopy are expanding without hard scientific evidence to support its efficacy. Therefore, it is extremely important to focus on potential harmful effects of the procedure itself. This review explores how physiology of the upper urinary tract reacts to ureterorenoscopy, potentially translating into harmful effects, and how such pathophysiological processes may be minimized.

RECENT FINDINGS

Complications to ureterorenoscopy and postoperative pain seem to be related to intrarenal pressure and/or access. Mean intrarenal pressures in the range of 60-100 mmHg during ureterorenoscopy without access sheaths have been measured, thus by far exceeding the threshold for intrarenal backflow, potentially resulting in septic complications. Intrarenal pressure may be reduced by use of ureteral access sheaths, which, however, may cause ureteral damage due to the limited size of the ureter and strain-induced ureteral contractions (peristalsis). Different receptor types modulate this peristaltic activity. β-receptor agonists have been investigated in animal and human trials for the purpose of relaxing the ureter. In randomized, placebo-controlled trials in pigs and humans, usage of the β-receptor agonist isoproterenol in the irrigation fluid has shown a potential for reducing both intrarenal pressure and ureteral tone during ureterorenoscopy.

SUMMARY

Upper urinary tract physiology has unique features that may be pushed into pathophysiological processes by the unique elements of ureterorenoscopy: access and irrigation. Pharmacological ureteral relaxation during ureterorenoscopy deserves further attention with regard to reducing complications and postoperative pain.

The Efficacy and Safety of Tamsulosin Combined with Extracorporeal Shockwave Lithotripsy for Urolithiasis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND PURPOSE

Many studies have been conducted to investigate adjunctive tamsulosin therapy after extracorporeal shockwave lithotripsy (SWL) for urolithiasis. The results from those studies, however, are still inconsistent. Therefore, we performed a meta-analysis to provide an update on the clinical efficacy and safety of tamsulosin combined with SWL for urolithiasis.

METHODS

A systematic search was performed in PubMed, Cochrane Library, and Embase to identify all relevant randomized controlled trials until January 2015. Two reviewers independently assessed trial quality and extracted data. Meta-analysis was conducted with Review Manager (RevMan), version 5.1.

RESULTS

Twenty-one studies (2093 subjects in total) were identified in the current meta-analysis. Compared with a control group, the experimental group (tamsulosin combined with SWL) showed an increased overall benefit for stone expulsion, with pooled risk ratio (RR) of 1.20 (95% confidence interval [CI], 1.15-1.26). With respect to the different geographic regions, European and American had a high possibility of improvement in stone expulsion (RR: 1.33, 95% CI, 1.19-1.49). According to the stone locations (renal, upper and lower ureteral) and sizes (4-10 mm and 11-24 mm), tamsulosin is more useful for lower ureteral stone (RR: 1.28; 95% CI, 1.14-1.43) and larger sized stones (RR: 1.49; 95% CI, 1.28-1.75). The effect estimates did not vary markedly when stratified by follow-up durations but varied by dose of tamsulosin. Furthermore, a shorter expulsion time, reduced occurrence of steinstrasse, fewer incidences of colic, and lower analgesic requirements were observed within the experimental group. In addition, tamsulosin is well tolerated, and its adverse events rarely led to dropouts of patients.

CONCLUSIONS

Overall, evidence suggests that tamsulosin combined with SWL is safe and effective in enhancing stone expulsion for patients with urolithiasis. Furthermore, high-quality, randomized and placebo-controlled trials evaluating the efficacy and safety of tamsulosin should be performed.

The effect of tamsulosin in the medical treatment of distal ureteral stones

INTRODUCTION

Renal stones are common disorders that affect approximately 5% to 10% of the population and the incidence of renal stones is rising. Treatment of ureteral stones is an important part of urologists and minimally invasive procedures such as ESWL and ureteroscopy effectiveness has been proven in various studies. However, these methods are not completely safe and are expensive and can be complicated. Purpose of this study is to evaluate the effectiveness of tamsulosin in the medical treatment of distal ureteral stones.

PATIENTS & METHODS

A total of 96 patients with distal ureteral stones or UVj are randomly divided into two study group (50 patients) and control group (46 patients). Patients in the control group allowed to freely consuming fluids (hydration) and indomethacin 100 mg PRN. Study group in addition to indomethacin and daily analgesic 0.4 mg tamsulosin was administered. All subjects in terms of analgesic dose, duration of expulsion and expulsion were studied.

RESULTS

Spontaneous expulsion of stone was occurred in 62.5% (30 patients out of 46) of control group patients and 82% (41 patients out of 50) that there was no significant difference (P>0.05). Average time to fix the stone in control group 4.7 ± 8.03 days (range 2 to 28 days) and in the study group, 3.7 ± 5.70 days (range 1 to 23 days) is significantly different (P>0.05). The average amount of analgesic consumption in the control group was 2.3 ± 4.31 and in the study group was 1.48 ± 2.15 that showed significant differences (P<0.05).

CONCLUSION

In this study, although the addition of tamsulosin to conservative treatment of distal ureteral stones in the distal ureteral stone expulsion showed no significant difference between the two groups, but the reduction in the duration of expulsion, reduce pain and reduce the need for analgesic has been beneficial.

Synthesis and cytotoxic activity evaluation of novel arylpiperazine derivatives on human prostate cancer cell lines

A series of novel arylpiperazine derivatives was synthesized. The in vitro cytotoxic activities of all synthesized compounds against three human prostate cancer cell lines (PC-3, LNCaP, and DU145) were evaluated by a CCK-8 assay. Compounds 9 and 15 exhibited strong cytotoxic activities against LNCaP cells (IC₅₀ < 5 μM), and compound 8 (IC₅₀ = 8.25 μM) possessed the most potent activity against DU145 cells. However, these compounds also exhibited cytotoxicity towards human epithelial prostate normal cells RWPE-1. The structure–activity relationship (SAR) of these arylpiperazine derivatives was also discussed based on the obtained experimental data.

Alpha-blockers as medical expulsive therapy for ureteral stones

BACKGROUND

Urinary stone disease is one of the most common reasons for patients visiting a urology practice, affecting about 5% to 10% of the population. Annual costs for stone disease have rapidly increased over the years and most patients with ureteral colic or other symptoms seek medical care. Stone size and location are important predictors of stone passage. In most cases medical expulsive therapy is an appropriate treatment modality and most studies have been performed with alpha-blockers. Alpha-blockers tend to decrease intra-ureteral pressure and increase fluid passage which might increase stone passage. Faster stone expulsion will decrease the rate of complications, the need for invasive interventions and eventually decrease healthcare costs. A study on the effect of alpha-blockers as medical expulsive therapy in ureteral stones is therefore warranted.

OBJECTIVES

This review aimed to answer the following question: does medical treatment with alpha-blockers compared to other pharmacotherapy or placebo impact on stone clearance rate, in adult patients presenting with symptoms of ureteral stones less than 10 mm confirmed by imaging? Other clinically relevant outcomes such as stone expulsion time, hospitalisation, pain scores, analgesic use and adverse effects have also been explored.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 9 July 2012 through contact with the Trials Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE, handsearching conference proceedings, and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs), comparing alpha-blockers with other pharmacotherapy or placebo on ureteral stone passage in adult patients were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes. Reporting bias was investigated using funnel plots. Subgroup analysis was used to explore possible sources of heterogeneity. Sensitivity analysis was performed removing studies of poor methodological quality.

MAIN RESULTS

Thirty-two studies (5864 participants) were included. The stone-free rates were significantly higher in the alpha-blocker group (RR 1.48, 95% CI 1.33 to 1.64) when compared to standard therapy. Stone expulsion time was 2.91 days shorter with the use of alpha-blockers (MD -2.91, 95% CI -4.00 to -1.81). Use of alpha-blockers reduced the number of pain episodes (MD -0.48, 95% CI -0.94 to -0.01), the need for analgesic medication (diclofenac) (MD -38.17 mg, 95% CI -74.93 to -1.41) and hospitalisation (RR 0.35, 95% CI 0.13 to 0.97). Patients using alpha-blockers were more likely to experience adverse effects when compared to standard therapy (RR 2.74, 95% CI 1.38 to 5.45) or placebo (RR 2.73, 95% CI 1.50 to 4.96). Most adverse effects were mild of origin and did not lead to cessation of therapy, and several studies reported no adverse events in either the treatment or control group.In 7/32 studies patients and doctors were both blinded. In the other studies blinding was not described in the methods or no blinding had taken place. Two studies described incomplete data and only one study showed a relatively high number of patients who withdrew from the study. These factors limited the methodological strength of the evidence found.

AUTHORS' CONCLUSIONS

The use of alpha-blockers in patients with ureteral stones results in a higher stone-free rate and a shorter time to stone expulsion. Alpha-blockers should therefore be offered as part of medical expulsive therapy as one of the primary treatment modalities.

Ureterovesical junction obstruction causes increment in smooth muscle contractility, and cholinergic and adrenergic activity in distal ureter of rabbits

BACKGROUND/PURPOSE

The controversy in management of primary obstructed megaureter necessitates further elucidation of the underlying pathophysiology. We evaluated smooth muscle contractility, and cholinergic, adrenergic and serotonergic activity of rabbit distal ureters after ureterovesical junction (UVJ) obstruction.

METHODS

Sham (SH) operation, partial obstruction (PO) and complete obstruction (CO) of the right UVJ were performed in rabbits. Three weeks later, distal ureters were isolated; spontaneous contractions (SC), contractile responses to electrical field stimulation (EFS), high KCl, carbachol, phenylephrine and serotonin were recorded.

RESULTS

SC amplitudes increased in CO compared to PO and SH (p<0.001). SC frequency was higher in CO (p<0.05). EFS-induced contraction amplitudes were greater in CO than other groups (p<0.05). High KCl-induced contractions were greater in CO (p<0.001) and PO (p<0.01). Carbachol-induced contractility was enhanced in CO and PO (p<0.05). Contractile response to phenylephrine was greater in CO than other groups (p<0.05). Serotonin induced contractile responses in CO and PO, greater in CO (p<0.05). UVJ obstruction also increased spontaneous contractility in contralateral PO and CO ureters.

CONCLUSIONS

UVJ obstruction increased spontaneous and neurotransmitter-induced contractions in an obstruction grade-dependent manner. Obstruction also altered contractility of the contralateral ureters. Our findings may serve to provide further understanding of the pathophysiology of megaureter.

Kidney stones: an update on current pharmacological management and future directions

INTRODUCTION

Kidney stones are a common problem worldwide with substantial morbidities and economic costs. Medical therapy reduces stone recurrence significantly. Much progress has been made in the last several decades in improving therapy of stone disease.

AREAS COVERED

This review discusses i) the effect of medical expulsive therapy on spontaneous stone passage, ii) pharmacotherapy in the prevention of stone recurrence and iii) future directions in the treatment of kidney stone disease.

EXPERT OPINION

Fluid intake to promote urine volume of at least 2.5 L each day is essential to prevent stone formation. Dietary recommendations should be adjusted based on individual metabolic abnormalities. Properly dosed thiazide treatment is the standard therapy for calcium stone formers with idiopathic hypercalciuria. Potassium alkali therapy is considered for hypocitraturia, but caution should be taken to prevent potential risk of calcium phosphate stone formation. For absorptive hyperoxaluria, low oxalate diet and increased dietary calcium intake are recommended. Pyridoxine has been shown effective in some cases of primary hyperoxaluria type I. Allopurinol is used in calcium oxalate stone formers with hyperuricosuria. Treatment of cystine stones remains challenging. Tiopronin can be used if urinary alkalinization and adequate fluid intake are insufficient. For struvite stones, complete surgical removal coupled with appropriate antibiotic therapy is necessary.

Management of ureteral calculi and medical expulsive therapy in emergency departments

Introduction:

Ureteral stones are a common problem in daily emergency department practice. Patients may be offered medical expulsive therapy (MET1) to facilitate stone expulsion and this should be offered as a treatment for patients with distal ureteral calculi, who are amenable to waiting management. Emergency department clinicians and family practitioners are often in the front line regarding the diagnosis and treatment of symptomatic nephrolithiasis and this commentary is dedicated to them because their decisions directly influence the outcome of the acute stone episode and appropriate referral patterns.

Materials and Methods:

The aim of this systematic review and meta-analysis was to understand the role of MET in the treatment of obstructing ureteral calculi. A bibliographic search covering the period from January 1980 to March 2010 was conducted in PubMed, MEDLINE and EMBASE. The searches were restricted to publications in English. This analysis is based on the 21 studies that fulfilled the predefined inclusion criteria.

Results:

A metaregression analysis of expulsion time showed a statistically significant advantage in the experimental group, in which the mean expulsion time was 6.2 days compared to 10.3 days in controls. The treatment effect on expulsion rate (P = 0.53) was partially lost as the size of the stones decreased because of the high spontaneous expulsion rate of small stones and the expulsion time was not influenced by pharmacological treatment (P = 0.76) if the stone size was smaller than 5 mm. Analysis of the tamsulosin database. A total of 1283 participants were included in the 17 studies. These studies showed that compared to standard therapy or placebo, tamsulosin had significant benefits, being associated with both a higher stone expulsion rate (P < 0.001) and reduction of the expulsion time (P = 0.02). Reductions in the need for analgesic therapy, hospitalization and surgery are also shown. Analysis of the nifedipine database. The number of participants in each trial ranged from 25 to 70. Compared to standard therapy, the use of nifedipine significantly improved the spontaneous stone expulsion rate (P < 0.001). The mean expulsion time was slightly, but not statistically significantly, different (P = 0.19) between the treatment and control groups. A possible benefit of nifedipine, in terms of significantly reducing the doses of analgesics required, was reported in three studies. There was no difference between the tamsulosin- and nifedipine-treated groups with regard to expulsion time (P = 0.17) or expulsion rate (P = 0.79).

Conclusions:

Despite all its advantages, MET is rarely used, representing a failure of the translation of medical science into practice. These data raise concerns not only about the quality of care of patients who could benefit from resolution of stones without anaesthetic and surgical risks but also with regard to potential cost savings. MET should be offered as a treatment for patients with distal ureteral calculi who are amenable to a waiting management.

Pharmacotherapy of urolithiasis: evidence from clinical trials

Urolithiasis is a worldwide problem with significant health and economic burdens. Medical therapy that alters the course of stone disease has enormous medical and financial impact. Urolithiasis is a final manifestation of a broad range of etiologies and pathogenesis. The modest progress in understanding the pathophysiology has hampered successful development of targeted therapy. Current regimens are based mostly on rational alteration of urinary biochemistry and physical chemistry to lower the risk of precipitation. In terms of pharmacotherapy, there are drugs to successfully improve hypercalciuria, hypocitraturia, aciduria, hyperuricosuria, and hypercystinuria. These agents have been proven to be effective in randomized controlled trials in improving urinary biochemical and physicochemical risk factors, as well as clinical outcomes. Although our current regimens have clearly improved the management and lives of stone formers, there are still clearly identifiable immense voids in the knowledge of pathophysiology of stone disease that can be filled with combined basic science and clinical studies.

Tamsulosin as an expulsive therapy for steinstrasse after extracorporeal shock wave lithotripsy: a randomized controlled study

OBJECTIVE

Steinstrasse is a well-known complication following extracorporeal shockwave lithotripsy (ESWL). The objective of this study was to evaluate the efficacy of tamsulosin as a management of steinstrasse.

MATERIAL AND METHODS

88 patients with unilateral steinstrasse were treated between January 2005 and December 2008. The patients were randomly allocated into two equal groups. There were no significant differences between groups for age, gender, stone location, stone length or stone fragment size (p > 0.05). Patients in group 1 (study group) received a single daily morning dose of tamsulosin (0.4 mg) for a maximum of 4 weeks, in addition to pain-relieving therapy. Patients in group 2 (control group) received only the pain-relieving therapy. All patients were checked weekly with a plain X-ray of the urinary tract, urinary ultrasonography, urine analysis and serum creatinine. Pain episodes, day of spontaneous stone expulsion, total analgesic dosage and drug side-effects were recorded.

RESULTS

Stone expulsion occurred in 32 of the 44 patients (72.7%) receiving tamsulosin and in 25 of the 44 patients (56.8%) in the control group. Patients receiving tamsulosin had a significantly higher stone expulsion rate (p = 0.017). There were no significant differences between groups for mean stone expulsion time or number of analgesics used. Twelve patients (27.3%) in the group receiving tamsulosin and 19 patients (43.3%) in the control group needed hospitalization; the group difference was statistically significant (p = 0.017).

CONCLUSIONS

When compared with no treatment, tamsulosin can significantly facilitate expulsion of retained ureteral stone fragments following ESWL.

Efficacy of tamsulosin in medical expulsive therapy for distal ureteral calculi

OBJECTIVE

To evaluate the potential role of tamsulosin in the medical treatment of distal ureteral stones.

MATERIAL AND METHODS

Ninety patients with symptomatic distal ureteral calculi were enrolled. They were randomly divided into two groups: Group A (n=45) received diclofenac 100 mg on demand for 4 weeks plus levofloxacin 250 mg daily for the first week and were well hydrated; and Group B (n=45) received the same therapy plus tamsulosin 0.4 mg/daily for 4 weeks. Abdominal ultrasound scans and KUB X-rays were performed weekly. Stone expulsion rates, time to expulsion, pain episodes and analgesic usage were determined. Intervention by means of shock-wave lithotripsy (SWL) or ureteroscopy was evaluated.

RESULTS

The stone expulsion rate was 51.1% for Group A, compared to 88.9% for Group B (p=0.001). The average time to expulsion was 12.53+/-2.12 days for Group A and 7.32+/-0.78 days for Group B (p=0.04). The number of pain episodes was significantly lower in Group B and mean use of analgesics was lower for Group B (0.14+/-0.5 vials) than Group A (2.78+/-2.7 vials). Twenty-two patients in Group A failed to pass their stones after 4 weeks but only five in Group B. Of the patients who were not stone-free, 19 were treated with SWL and eight underwent ureteroscopy.

CONCLUSION

Our study reveals the efficacy of tamsulosin for the treatment of distal ureteral stones. Tamsulosin should be added to the standard medical approach for treating these stones.

Endoluminal isoproterenol reduces renal pelvic pressure during semirigid ureterorenoscopy: a porcine model

OBJECTIVE

To investigate the effects on the pressure-flow relation of renal pelvic pressure during semirigid ureterorenoscopy and endoluminal perfusion of isoproterenol (ISO) 0.1 microg/mL, with emphasis on local effects and cardiovascular side-effects, as topically administered ISO effectively and dose-dependently causes relaxation of the upper urinary tract in pigs with no concomitant cardiovascular side-effects.

MATERIALS AND METHODS

In anaesthetized female pigs (60 kg), 16 macroscopically normal upper urinary tract systems were subjected to ureterorenoscopy. Via a subcostal incision a 6-F catheter was placed in the renal pelvis for pressure measurements, and a semirigid ureteroscope (7.8 F) was inserted retrogradely in the renal pelvis, through which the pelvis was perfused. The blood pressure and heart rate were recorded. The increase in renal pelvic pressure was examined with increasing flow rates (0, 4, 8, 12, 16, 25 and 33 mL/min) with saline alone or saline + ISO 0.1 microg/mL. Perfusion was initiated on the left side, with randomization for adding ISO or not. Thereafter perfusion was done on the right side as a control in each pig. The surgeons were unaware of whether ISO was added or not.

RESULTS

The mean (sd) baseline pelvic pressures in the saline and ISO group were 28 (7.1) and 25 (9.8) mmHg, respectively, with no significant difference (P = 0.079). Endoluminal perfusion with ISO significantly inhibited the pelvic pressure increase to perfusion at all perfusion rates. The pressure-flow relation was linear; the maximum relaxation (27%) was obtained at 4 mL/min, from 52 to 38 mmHg during saline alone and ISO 0.1 microg/mL perfusion, respectively. The mean blood pressure did not change significantly (P = 0.330). The mean (sd) heart rate in the saline and ISO group were 109 (4.5) and 97 (2.1) beats/min, respectively (P < 0.001), i.e. a markedly greater rate in the saline than in the ISO group.

CONCLUSION

The pressure-flow relation during semirigid ureterorenoscopy was linear. ISO 0.1 microg/mL in saline significantly reduced the pressure-flow relation during semirigid ureterorenoscopy in this porcine model. ISO might be a potential additive to the irrigation fluid during upper urinary tract endoscopic procedures, minimizing pressure increases due to irrigation and manipulation.

Medical therapy of stone disease: from prevention to promotion of passage options

Medical therapy has been used for many years in the prevention of urinary stones. Medications directed at correcting urinary metabolic abnormalities responsible for promoting stone formation include thiazide diuretics, citrate salts, and allopurinol. All have proven to be efficacious. In addition, intake of citrate-rich juices, such as lemonade, may help to reduce urinary stone formation. More recently, there has been increasing interest in and use of medical therapy to aide in the passage of ureteral stones. Medical expulsive therapy (MET) has been shown to be cost effective compared with observation followed by treatment. Alpha-adrenergic receptor blockers are most commonly prescribed to promote passage of ureteral stones. They are able to facilitate stone passage, reduce time to passage, and decrease pain. Calcium-channel blockers also increase stone-passage rates. Steroids are useful adjuncts in MET.

Efficacy of selective alpha1D-blocker naftopidil as medical expulsive therapy for distal ureteral stones

PURPOSE

Naftopidil is a specific alpha1D-adrenergic receptor antagonist. We performed the current randomized, controlled study to determine the expulsive role of naftopidil for distal ureteral stones.

MATERIALS AND METHODS

From March 2006 to January 2007, 60 patients with distal ureteral stones were randomly divided into groups 1 and 2. Group 1 served as the control and underwent watchful waiting, while group 2 received 50 mg naftopidil daily in the morning. All patients were instructed to drink a minimum of 2 l water daily. The stone expulsion rate and time, potential side effects of naftopidil, number of pain episodes and requirements for pain medication were documented during the 14-day followup.

RESULTS

All patients in groups 1 and 2 completed the study. There was no difference between the groups in patient age, sex and stone size. The stone expulsion rate was significantly higher in group 2 than in group 1 (90.0% vs 26.7%, p <0.01). No significant difference in expulsion time was noted between the groups. No patients experienced obvious naftopidil side effects or ureteral colic. Multivariate analysis using a Cox proportional hazards model indicated that the probability of expulsion was increased 5.263 times (95% CI 2.304-12.024) in group 2 compared with that in group 1 (p <0.001).

CONCLUSIONS

The selective alpha1D-blocker naftopidil can significantly facilitate spontaneous passage of distal ureteral stones with few side effects, providing a new choice for medical expulsive therapy.

Demonstration of intrinsic innervation of the guinea pig upper urinary tract using whole-mount preparation

AIMS

The morphology and functional importance of the autonomic nervous system in the upper urinary tract is still not completely understood. Previous histological studies investigating the innervation of the urinary tract have mainly used conventional sections in which the three-dimensional structure of the intramural innervation is difficult to achieve. In contrast, the whole-mount preparation technique is a suitable method for visualizing the distribution of the mesh-like neuronal networks within the urinary tract.

METHODS

The distribution and regional variation of neurofilament (NF), tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), and substance P-immunoreactive (SP-IR) neurons, as well as acetylcholinesterase (AChE) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-positive neurons were investigated using whole-mount preparations of the guinea pig upper urinary tract.

RESULTS

Two distinct nervous plexuses were detected within the muscle layers containing NF, TH, ChAT, and SP-IR nerves. AChE-positive nerves were seen in all layers. Only moderate NADPH-d-positive innervation was found. Renal pelvis, upper and lower part of the ureter showed an overall increased innervation compared to the middle portion of the ureter. Ganglia were found at the pelviureteric border displaying NF and TH immunoreactivity.

CONCLUSION

The whole-mount preparation technique provides an elegant method for assessing the three-dimensional architecture of ureteral innervation. The guinea pig upper urinary tract is richly supplied with adrenergic, cholinergic, nitrergic, and sensory nerves which suggest that the autonomous nervous system plays an important role in controlling ureteral motility and blood flow.

Pharmacological effect on pyeloureteric dynamics with a clinical perspective: a review of the literature

We searched to review experimental and clinical trials concerning the capabilities of impacting on the ureteric and pelvic activity by means of pharmacological stimulation. Ureteropyeloscopy may cause high renal pelvic pressure. The normal pressure is in the range of 5-15 mmHg whereas pressure of 410 mmHg has been measured during endoscopy. The threshold pressure for intrarenal reflux is about 35 mmHg. Studies in animals have revealed that high renal pelvic pressures may cause permanent damage to the renal parenchyma. Furthermore, it has been demonstrated that elevated pressures may entail an increased risk of several complications related to endourological procedures including bleeding, perforation and infection. In other words, means by which intrarenal pressure could be lowered during endourological procedures might be beneficial with respect to clinical outcomes. In vitro experiments support the existence of different receptors in the ureter and renal pelvis. The ureteric and pelvic responses to the corresponding neurotransmitters have been determined. It seems that alpha-adrenergic and cholinergic agents are stimulating whereas beta-adrenergic agents inhibit ureteric activity. The effect may depend on the mode of administration. Drugs exerting advantageous effects in the pyeloureter may cause undesirable systemic side effects when administered intravenously. In animal studies, renal pelvic pressure can be significantly lowered by topical administration of beta-adrenergic agonists without systemic side effects. In vivo human studies are necessary to clarify the exact dose-response relationship and the degree of urothelial absorption of a drug before clinical use may be adopted.

Physiology and pharmacology of the human ureter: basis for current and future treatments

INTRODUCTION

This article sets out to be a review regarding agents that affect contraction and relaxation of the ureter in order to establish a basis for current and future treatments for upper urinary tract obstruction.

MATERIAL AND METHODS

A complete review of the English literature using MEDLINE was performed between 1960 and 2007 on ureter physiology and pharmacology with special emphasis on signal transduction mechanisms involved in the contractile regulation of the human ureter.

RESULTS

Activation of muscarinic and adrenergic receptors increases the amplitude of ureteral contractions. The sympathetic nerves modulate the contractions by alpha-adrenoceptors and relaxation by beta-adrenoceptors. The purinergic system is important in sensory/motor functions and ATP is an important non-adrenergic non-cholinergic (NANC) agent causing contraction. Nitric oxide (NO) is a major inhibitory NANC neurotransmitter causing relaxation. Serotonin causes contraction. Prostaglandin-F(2)alpha contracts whereas prostaglandin-E(1)/E(2) relaxes the ureter. Phosphodiesterases (PDE) and the Rho-kinase pathway have recently been identified in the human ureter. PDE-IV inhibitors, K(+) channel openers, calcium antagonists, alpha(1)-adrenoceptor antagonists and NO donors seem to be promising drugs in relieving obstruction and facilitating stone passage.

CONCLUSIONS

Further understanding of the ureteral function and pharmacology may lead to the discovery of promising new drugs that could be useful in relieving ureteral colic, facilitating spontaneous stone passage, preparing the ureter for ureteroscopy as well as acting adjunctive to extracorporeal shock-wave lithotripsy.

Is There a Role for Tamsulosin in Shock Wave Lithotripsy for Renal and Ureteral Calculi?

PURPOSE

We evaluated the effect of the alpha-blocker tamsulosin on stone clearance, analgesic requirements and steinstrasse in shock wave lithotripsy for solitary renal and ureteral calculus.

MATERIALS AND METHODS

A prospective, double-blind, randomized placebo controlled study was performed during 1 year involving 60 patients with a solitary renal or ureteral calculus undergoing shock wave lithotripsy. The control group (30) received 0.4 mg tamsulosin and the study group (30) received placebo daily until stone clearance or for a maximum of 30 days. An oral preparation of dextropropoxyphene hydrochloride and acetaminophen was the analgesic used on an on-demand basis. The parameters assessed were stone size, position, clearance time, effect on steinstrasse and analgesic requirement.

RESULTS

The overall clearance rate was 96.6% (28 of 29) in the study group and 79.3% (23 of 29) in the control group (p = 0.04). With larger stones 11 to 24 mm the difference in the clearance rate was significant (p = 0.03) but not so with the smaller stones 6 to 10 mm (p = 0.35). The average dose of analgesic used was lower with tamsulosin than with controls, without statistical significance. Steinstrasse resolved spontaneously in the tamsulosin group whereas 25% (2 of 8) required intervention in the placebo group. There was no difference between the 2 groups with regard to age, stone size or location.

CONCLUSIONS

The alpha-blocker tamsulosin seemed to facilitate stone clearance, particularly with larger stones during shock wave lithotripsy for renal and ureteral calculus. It also appeared to improve the outcome of steinstrasse. Tamsulosin may have a potential role in routine shock wave lithotripsy.

Effect of smooth muscle relaxant drugs on proximal human ureteric activity in vivo: a pilot study

Drugs are increasingly being used to promote stone passage in renal colic. Diclofenac, nifedipine and tamsulosin cause ureteric smooth muscle relaxation in vitro; however, in clinical trials nifedipine and tamsulosin promote stone passage whereas diclofenac has no apparent benefit. We adapted a ureteric pressure transducer catheter in an attempt to compare the human ureteric response to these drugs in vivo. The catheter was inserted into the contralateral ureter following ureteroscopy for stone disease. Contraction frequency, pressure and velocity measurements were recorded at 24 h. Each patient was randomly allocated to receive oral diclofenac, nifedipine or tamsulosin. Measurements were taken following drug administration. Eighteen patients (mean age 50 years) were recruited. Two patients were excluded intraoperatively and three required early removal of the catheter. Prior to drug administration, the mean number of contractions recorded was 0-4.1/min and the peak contraction pressure ranged from 11 to 35 mmHg. Conduction velocity ranged from 1.5 to 2.6 cm/s. Ureteric peristalsis persisted in all patients despite these drugs. Diclofenac and nifedipine produced inconsistent ureteric pressure responses but had little effect on contraction frequency. Tamsulosin significantly reduced ureteric pressure but had no effect on contraction frequency. There are many limitations associated with the use of ureteric catheters, however, they may provide some useful information when used to record the response to an intervention in the same patient. These preliminary results suggest a reduction in pressure generation may be the essential factor in the promotion of stone passage. More work is required but these drugs may work by preventing the increased, uncoordinated muscular activity seen in renal colic whilst maintaining peristalsis, thereby promoting stone passage.