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Concept: Urethra


BACKGROUND: To investigate the effect of prostaglandin depletion by means of COX-inhibition on cholinergic enhanced spontaneous contractions. METHODS: The urethra and bladder of 9 male guinea pigs (weight 270–300 g) were removed and placed in an organ bath with Krebs' solution. A catheter was passed through the urethra through which the intravesical pressure was measured. The muscarinic agonist arecaidine, the non-selective COX inhibitor indomethacin, and PGE2 were subsequently added to the organ bath. The initial average frequency and amplitude of spontaneous contractions in the first 2 minutes after arecaidine application were labelled Fini and Pini, respectively. The steady state frequency (Fsteady) and amplitude (Psteady) were defined as the average frequency and amplitude during the 5 minutes before the next wash out. RESULTS: Application of 1 muM PGE2 increased the amplitude of spontaneous contractions without affecting frequency. 10 muM of indomethacin reduced amplitude but not frequency.The addition of indomethacin did not alter Fini after the first application (p = 0.7665). However, after the second wash, Fini was decreased (p = 0.0005). Fsteady, Psteady and Pini were not significantly different in any of the conditions. These effects of indomethacin were reversible by PGE2 addition.. CONCLUSIONS: Blocking PG synthesis decreased the cholinergically stimulated autonomous contractions in the isolated bladder. This suggests that PG could modify normal cholinergically evoked response. A combination of drugs inhibiting muscarinic receptors and PG function or production can then become an interesting focus of research on a treatment for overactive bladder syndrome.

Concepts: Urine, Urology, Urinary bladder, Urinary system, Urethra, Ureter, Urogenital sinus, Guinea pig


Many urological studies rely on models of animals, such as rats and pigs, but their relation to the human urinary system is poorly understood. Here, we elucidate the hydrodynamics of urination across five orders of magnitude in body mass. Using high-speed videography and flow-rate measurement obtained at Zoo Atlanta, we discover that all mammals above 3 kg in weight empty their bladders over nearly constant duration of 21 ± 13 s. This feat is possible, because larger animals have longer urethras and thus, higher gravitational force and higher flow speed. Smaller mammals are challenged during urination by high viscous and capillary forces that limit their urine to single drops. Our findings reveal that the urethra is a flow-enhancing device, enabling the urinary system to be scaled up by a factor of 3,600 in volume without compromising its function. This study may help to diagnose urinary problems in animals as well as inspire the design of scalable hydrodynamic systems based on those in nature.

Concepts: Blood, Urine, Mass, Urinary bladder, Urinary system, Urethra, Urination, Fluid mechanics


Loss of bladder control is a challenging outcome facing patients with spinal cord injury (SCI). We report that systemic blocking of pro-nerve growth factor (proNGF) signaling through p75 with a CNS-penetrating small-molecule p75 inhibitor resulted in significant improvement in bladder function after SCI in rodents. The usual hyperreflexia was attenuated with normal bladder pressure, and automatic micturition was acquired weeks earlier than in the controls. The improvement was associated with increased excitatory input to the spinal cord, in particular onto the tyrosine hydroxylase-positive fibers in the dorsal commissure. The drug also had an effect on the bladder itself, as the urothelial hyperplasia and detrusor hypertrophy that accompany SCI were largely prevented. Urothelial cell loss that precedes hyperplasia was dependent on p75 in response to urinary proNGF that is detected after SCI in rodents and humans. Surprisingly, death of urothelial cells and the ensuing hyperplastic response were beneficial to functional recovery. Deleting p75 from the urothelium prevented urothelial death, but resulted in reduction in overall voiding efficiency after SCI. These results unveil a dual role of proNGF/p75 signaling in bladder function under pathological conditions with a CNS effect overriding the peripheral one.

Concepts: Urology, Urinary incontinence, Urinary bladder, Urinary system, Urethra, Urination, Hyperplasia, Hypertrophy


OBJECTIVE: To develop and test the safety and feasibility of a novel anti-biofilm mechanism configured for wireless capsule endoscopy (WCE) in a sheep bladder model. MATERIALS AND METHODS: A WCE mechanism, designed for long-term bladder monitoring, was developed and introduced into a sheep bladder for 5 months. The transparency of the surface was assessed by evaluating a resolution target placed inside the capsule at serial intervals using cystoscopy under general anaesthesia. Animal behaviour, voiding patterns and urine cultures were monitored throughout the study. At study termination, the capsule was extracted and assessed using scanning electron microscopy. RESULTS: The resolution target was visualized clearly at all investigation points. No notable adverse effects were noted during the entire follow-up period and no urinary tract infection occurred. Scanning electron microscopy confirmed the efficacy of the technology to prevent biofilm formation and surface encrustation. CONCLUSIONS: We report a novel technology that effectively prevents biofilm formation on the outer surface of foreign objects in the urinary tract. Further studies are under way to test the applicability of this technology in bladder WCE to enable high-quality wireless image transmission.

Concepts: Kidney, Urinary tract infection, Urine, Urinary bladder, Urinary system, Urethra, Scanning electron microscope, Endoscopy


PURPOSE: The long-term success rate of dilation and/or internal urethrotomy is low in cases of recurrent urethral stricture disease. This study investigated the Memokath™044TW stent’s ability to maintain urethral patency after dilation or internal urethrotomy of recurrent urethral stricture. MATERIALS AND METHODS: Ninety-two patients with recurrent bulbar urethral strictures (mean length 2.7 cm) were treated with dilation or internal urethrotomy and randomized to short-term urethral catheter diversion (N=29) or insertion of a Memokath™044 stent (N=63). The primary endpoint was urethral patency as assessed by the passage of a calibrated endoscope. Secondary endpoints included urinary symptoms and uroflowmetry parameters. Stents were scheduled to remain in situ 12 months. RESULTS: The rate of successful stent insertion was 93.6% (59/63). The stented patients maintained patency significantly longer than controls (292 days vs. 84 days (median), p<0.001). The patency was reflected in significantly improved uroflowmetry and symptom scores. The stent was removed in 100% of patients. The most frequently noted side-effects in the stented patients were bacteriuria, hematuria, and penile pain - all usually mild and transient. There were no differences in sexual function between the Memokath and control patients. Stent dislocation and occlusion were observed in eight and three patients, respectively. CONCLUSIONS: Patients with recurrent bulbar urethral strictures treated with dilation or urethrotomy and a Memokath™044 stent maintained urethral patency significantly longer than those treated with dilation or urethrotomy alone. The stent's side-effect profile was favorable. The stent was straightforward to insert and was removed without difficulty - even after long-term placement.

Concepts: Time, Medical terms, Urethra, Stent, Restenosis, Urethral stricture, Urethrotomy, Insertion


Strictures of the urethra are the most common cause of obstructed micturition in younger men and frequently recur after initial treatment. Standard treatment comprises internal widening of the strictured area by simple dilatation or by telescope-guided internal cutting (optical urethrotomy), but these interventions are associated with a high failure rate requiring repeated treatment. The alternative option of open urethroplasty whereby the urethral lumen is permanently widened by removal or grafting of the strictured segment is less likely to fail but requires greater expertise. Findings of Improved choice of graft material and shortened hospital stay suggest that urethroplasty may be under utilised. The extent and quality of evidence guiding treatment choice for this condition are uncertain.  

Concepts: Urethra, Urination, Failure, Urethral stricture, Failure rate, Urethrotomy, Reliability engineering, Cystoscopy


We assessed the risk of upper urinary tract obstruction and tumor recurrence following ureteral orifice resection during transurethral resection of bladder tumor.

Concepts: Kidney, Urine, Urology, Urinary bladder, Urinary system, Urethra, Ureter, Prostatic stent


We present a unique case of a large urinary bladder stone protruding through the external urethral meatus in a 77-year-old woman, which was causing acute urinary retention, complicated by bilateral hydronephrosis, and was removed under topical anesthesia in the emergency department. Epidemiology, etiology, clinical presentation and management of urinary bladder stones are briefly discussed.

Concepts: Kidney, Urine, Urology, Urinary bladder, Urinary system, Urethra, Urinary retention, Urinary meatus


WHAT’S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Despite high morbidities, TURP is still considered as the ‘gold standard’ for treatment of BPH. Photoselective vaporization of the prostate (PVP) is a promising technique that is emerging as a possible alternative to TURP. However, there remains some debate about the advantages of PVP over TURP and whether PVP will be able to replace TURP as the first-line surgical treatment. We conducted a meta-analysis of recent papers on this subject and herein provide the overall efficacy and safety of PVP for treatment of BPH. OBJECTIVE: To assess the overall efficacy and safety of photoselective vaporization of the prostate (PVP) vs transurethral resection of the prostate (TURP) for treating patients with lower urinary tract symptoms (LUTS) secondary to benign prostate hyperplasia (BPH). PATIENTS AND METHODS: A systematic search of the electronic databases, including MEDLINE, Embase, Web of Science and The Cochrane Library, as well as manual bibliography searches were performed. The pooled estimates of maximum flow rate (Q(max) ), postvoid residual (PVR), quality of life (QoL), International Prostate Symptom Score (IPSS), operation duration, blood loss, catheterization time, hospital stay, capsule perforation, transfusion, transurethral resection (TUR) syndrome, urethral stricture and reintervention were calculated. RESULTS: At the 3-month follow-up, there was no significant difference in Q(max) , PVR, QoL and IPSS between the TURP and PVP groups. At the 6-month follow-up, the pooled QoL favoured TURP, but there was no significant difference in the other variables between the two groups. PVP was associated with less blood loss, transfusion, capsular perforation, TUR syndrome, shorter catheterization time and hospital stay, but longer operation duration and higher reintervention rate. CONCLUSIONS: The efficacy of PVP was similar to that of TURP in relation to Q(max) , PVR, QoL and IPSS, and it offered several advantages over TURP. As a promising minimal invasive technique, PVP could be used as an alternative surgical procedure for treating BPH.

Concepts: Blood, Evidence-based medicine, Urology, Urethra, Benign prostatic hyperplasia, International Prostate Symptom Score, Prostatic stent, Transurethral microwave thermotherapy


Prevention of recurrent calcium stone disease includes treatment with thiazide and thiazide-type diuretics to reduce urinary calcium (UCa) levels, with the reduction in UCa correlating with risk of stone recurrence. There has been a recent trend of using lower doses of these medications and change from chlorthalidone (CTL) use to hydrochlorothiazide (HCTZ) use. It is unknown whether low doses of HCTZ are effective in lowering UCa levels to target levels. We hypothesize that HCTZ is associated with less reduction in UCa than is CTL when comparing currently used doses. Retrospective observational study of stone-formers was seen in metabolic stone clinic during a 3 years period. Data included patient demographics, co-morbidities, and 24 h urine electrolyte composition. Primary outcome was the change in 24 h UCa. 322 patients were identified with 112 meeting criteria and used in analysis. The majority were placed on HCTZ (n = 42) or CTL (n = 47) 25 mg QD. Patients on CTL 25 mg had a greater reduction in UCa (164 mg; 41 %) than those on HCTZ (85 mg; 21 %), p = 0.01. Neither CTL nor HCTZ at 12.5 mg QD significantly lowered UCa. There was a decrease in serum [K] of 0.5 Meq/L (p = 0.001) in patients on CTL 25 mg daily, but no significant difference in severe hypokalemia or arrhythmia compared to HCTZ. Our data show that CTL is associated with greater reduction in 24 h UCa compared to similarly dosed HCTZ.

Concepts: Kidney, Observational study, Urinary bladder, Urethra, Gout, Diuretic, Hydrochlorothiazide, Hypokalemia