Nondistended Bladder Research Articles

Mechanosensitive Hydrolysis of ATP and ADP in Lamina Propria of the Murine Bladder by Membrane-Bound and Soluble Nucleotidases.

Prior studies suggest that urothelium-released adenosine 5′-triphosphate (ATP) has a prominent role in bladder mechanotransduction. Urothelial ATP regulates the micturition cycle through activation of purinergic receptors that are expressed in many cell types in the lamina propria (LP), including afferent neurons, and might also be important for direct mechanosensitive signaling between urothelium and detrusor. The excitatory action of ATP is terminated by enzymatic hydrolysis, which subsequently produces bioactive metabolites. We examined possible mechanosensitive mechanisms of ATP hydrolysis in the LP by determining the degradation of 1,N 6 -etheno-ATP (eATP) at the anti-luminal side of nondistended (empty) or distended (full) murine (C57BL/6J) detrusor-free bladder model, using HPLC. The hydrolysis of eATP and eADP was greater in contact with LP of distended than of nondistended bladders whereas the hydrolysis of eAMP remained unchanged during filling, suggesting that some steps of eATP hydrolysis in the LP are mechanosensitive. eATP and eADP were also catabolized in extraluminal solutions (ELS) that were in contact with the LP of detrusor-free bladders, but removed from the organ chambers prior to addition of substrate. The degradation of both purines was greater in ELS from distended than from nondistended preparations, suggesting the presence of mechanosensitive release of soluble nucleotidases in the LP. The released enzyme activities were affected differently by Ca2+ and Mg2+. The common nucleotidase inhibitors ARL67156, POM-1, PSB06126, and ENPP1 Inhibitor C, but not the alkaline phosphatase inhibitor (-)-p-bromotetramisole oxalate, inhibited the enzymes released during bladder distention. Membrane-bound nucleotidases were identified in tissue homogenates and in concentrated ELS from distended preparations by Wes immunodetection. The relative distribution of nucleotidases was ENTPD1 >> ENPP1 > ENTPD2 = ENTPD3 > ENPP3 = NT5E >> ENTPD8 = TNAP in urothelium and ENTPD1 >> ENTPD3 >> ENPP3 > ENPP1 = ENTPD2 = NT5E >> ENTPD8 = TNAP in concentrated ELS, suggesting that regulated ectodomain shedding of membrane-bound nucleotidases possibly occurs in the LP during bladder filling. Mechanosensitive degradation of ATP and ADP by membrane-bound and soluble nucleotidases in the LP diminishes the availability of excitatory purines in the LP at the end of bladder filling. This might be a safeguard mechanism to prevent over-excitability of the bladder. Proper proportions of excitatory and inhibitory purines in the bladder wall are determined by distention-associated purine release and purine metabolism.

Acoustic radiation force imaging (ARFI) in the non-distended bladder does not predict abnormal urodynamic parameters in children.

Acoustic radiation force imaging (ARFI) is a recently developed form of ultrasound imaging that allows in vivo measurement of tissue stiffness. This technology could be useful at predicting bladder compliance in children. We hypothesize that tissue stiffness, as measured by ARFI, correlates with abnormal bladder compliance and capacity in patients with bladder dysfunction. Patients who presented for cystometrography (CMG) underwent ARFI of the bladder wall. Nine bladder wall shear wave speed (SWS) measurements were acquired using point and 2D ultrasound shear wave elastography. The mean for each ARFI technique was correlated to bladder compliance, calculated using Wahl's dimensionless number. ARFI parameters also were correlated with bladder capacity. A total of 25 patients were enrolled. Mean age at time of enrollment was 4.2±3.9 years (range two months to 15 years). There was no significant correlation between bladder compliance and point shear wave speed measurements (r=-0.22, p=0.31) or 2D shear wave speed measurements (r=-0.35, p=0.1). A total of 19 patients had bladder capacity below expected bladder capacity (EBC). There was no significant correlation between bladder capacity and point shear wave speed measurements (r =-0.08, p=0.7) or 2D shear wave speed measurements (r=-0.36, p=0.09). Our results did not demonstrate a significant correlation between bladder wall ARFI shear wave measurements and bladder compliance or bladder capacity. Further studies are warranted to determine whether ARFI may be used to predict abnormal urodynamic parameters in children.

Non-visualization of the ovaries on pediatric transabdominal ultrasound with a non-distended bladder: Can adnexal torsion be excluded?

The pediatric reproductive organs are optimally imaged with a full bladder. The filling of the bladder, however, often leads to significant delay in diagnosis and can subject the patient to invasive bladder catheterization. As the key imaging feature in ovarian torsion is unilateral ovarian enlargement, we suspected that a torsed ovary is large enough to be visualized even if the bladder is not well distended. The purpose of this study was to retrospectively investigate if clinically suspected adnexal torsion can be excluded based on non-visualization of the ovaries on transabdominal ultrasound (US) with a non-distended bladder in pediatric patients. This retrospective study comprised 349 girls (1-19years old) between Jan. 1, 2013, and July 30, 2018. Three hundred and forty-one of the girls were referred to transabdominal US to assess for adnexal torsion and/or appendicitis, and the ovaries were initially not visualized on US. Their bladders were subsequently filled and rescanned with a distended bladder showing the ovaries. Ovarian volumes and time between US scans were documented. The ratio of the volume of the larger ovary to the smaller one was calculated. Nine girls had surgically proven adnexal torsion and a preoperative transabdominal US with a non-distended bladder. There was an overlap of one girl between the two groups. The negative predictive value (NPV), positive predictive value (PPV), and sensitivity and specificity for exclusion of adnexal torsion based on non-visualization of the ovaries on US with a non-distended bladder were calculated. One of the girls (1/341) who had a US study done with a non-distended bladder in which the ovaries were not visualized had a positive diagnosis of adnexal torsion. In eight of the nine girls who had surgically proven adnexal torsion, the torted ovary was identified with a non-distended bladder. The NPV and PPV for exclusion of adnexal torsion with a non-distended bladder was 1.0 and 0.8, respectively. The specificity and sensitivity were 99.4% and 88.9%, respectively. The mean and median time difference between the initial scan and the scan after bladder filling was 105.1 min (standard deviation [SD] -65.8) and 89.0 min (interquartile range [IQR]- 59.0, 130.5), respectively. Non-visualization of the ovaries with a non-distended bladder on transabdominal US study can help exclude clinically suspected adnexal torsion, alleviating the need for bladder filling and prolonging the wait time in the emergency department. Inclusion of non-visualization of the ovaries as one of the features in a predictive score for adnexal torsion should be considered.

MRI-based reference range for the renal pelvis anterior-posterior diameter in children ages 0-19 years.

To determine the mean and normal range of anteroposterior diameter (APD) of the renal pelves in children. Patients aged 0-19 years with normal spinal MRIs were identified after institutional review board approval. Those with dilating uropathy or abdominal surgery/radiation were excluded. The maximum APD was measured. A mixed linear model was fit to determine the relationship between APD and age, adjusted for bladder distention. The left and right kidneys were treated independently. 283 left and 285 right renal units were included. For the left, a 3.5% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.5 mm (95th percentile: 7.2 mm) and 4.6 mm (13.4 mm), respectively. For the right, a 3.9% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.8 mm (8.4 mm) and 5.5 mm (16.6 mm), respectively. Compared with a non-distended bladder, a distended bladder increased the predicted APD between 23% (right) and 38% (left) (p = 0.01 and p < 0.0001, respectively). The mean and normal ranges of APD measured by MRI in children are provided. APD increases with age and bladder distension and is greater on the left. Advances in knowledge: This article establishes normative ranges for APD, a critical component of genitourinary tract evaluation, and does so using the most precise imaging modality for this condition.

Recognition of Anterior Peritoneal Reflections and Their Relationship With Rectal Tumors Using Rectal Magnetic Resonance Imaging.

Our goal was to explore the factors influencing the visualization of anterior peritoneal reflections (APRs) using rectal MRI. We evaluated the usefulness of rectal MRI in measuring the distance from the anal verge to the APR and determining the relationship between the APR and the rectal tumor.Clinical and imaging data from 319 patients who underwent surgery after MRI examination between October 2010 and December 2013 were retrospectively analyzed. The distance from the anal verge to the APR and the relationship between the APR and the location of the rectal tumor was evaluated. analysis of variance, logistic regression, independent samples t tests, and Kappa tests were used for statistical analysis.The APR was visible in 283 of 319 cases using rectal MRI. The APR was more readily observed in patients who were older than 58 years (P = 0.046), in patients whose subcutaneous fat thicknesses were >22.2 mm (P = 0.004), in patients with nondistended bladders (P = 0.001), and in those with an anteversion of the uterus (P = 0.001). There was a significant difference between the distance from the anal verge to the APR between females (10.4 ± 1.1 cm) and males (10.0 ± 1.2 cm; P = 0.014). The accuracy in predicting tumor location with respect to the APR was 70%, 50%, 98.2%, respectively for patients with tumors located above, at, and below the APR (compared with the location determined during surgery).Most of the APRs were visible using rectal MRI, whereas certain internal factors influence visualization. Rectal MRI could be a useful tool for evaluating the distance from the anal verge to the APR and relationship between rectal tumors and the APR.

Pannexin 1 channels mediate the release of ATP into the lumen of the rat urinary bladder.

ATP is released through pannexin channels into the lumen of the rat urinary bladder in response to distension or stimulation with bacterial endotoxins. Luminal ATP plays a physiological role in the control of micturition because intravesical perfusion of apyrase or the ecto-ATPase inhibitor ARL67156 altered reflex bladder activity in the anaesthetized rat. The release of ATP from the apical and basolateral surfaces of the urothelium appears to be mediated by separate mechanisms because intravesical administration of the pannexin channel antagonist Brilliant Blue FCF increased bladder capacity, whereas i.v. administration did not. Intravesical instillation of small interfering RNA-containing liposomes decreased pannexin 1 expression in the rat urothelium in vivo and increased bladder capacity. These data indicate a role for pannexin-mediated luminal ATP release in both the physiological and pathophysiological control of micturition and suggest that urothelial pannexin may be a viable target for the treatment of overactive bladder disorders. ATP is released from the bladder epithelium, also termed the urothelium, in response to mechanical or chemical stimuli. Although numerous studies have described the contribution of this release to the development of various bladder disorders, little information exists regarding the mechanisms of release. In the present study, we examined the role of pannexin channels in mechanically-induced ATP release from the urothelium. PCR confirmed the presence of pannexin 1 and 2 mRNA in rat urothelial tissue, whereas immunofluorescence experiments localized pannexin 1 to all three layers of the urothelium. During continuous bladder cystometry in anaesthetized rats, inhibition of pannexin 1 channels using carbenoxolone (CBX) or Brilliant Blue FCF (BB-FCF) (1-100μm, intravesically), or by using intravesical small interfering RNA, increased the interval between voiding contractions. Intravenous administration of BB-FCF (1-100μgkg(-1) ) did not alter bladder activity. CBX or BB-FCF (100μm intravesically) also decreased basal ATP concentrations in the perfusate from non-distended bladders and inhibited increases in ATP concentrations in response to bladder distension (15 and 30cmH2 Opressure). Intravesical perfusion of the ATP diphosphohydrolase apyrase (2Uml(-1) ), or the ATPase inhibitor ARL67156 (10μm) increased or decreased reflex bladder activity, respectively. Intravesical instillation of bacterial lipopolysaccharides (LPS) (Escherichia coli 055:B5, 100μgml(-1) ) increased ATP concentrations in the bladder perfusate, and also increased voiding frequency; these effects were suppressed by BB-FCF. These data indicate that pannexin channels contribute to distension- or LPS-evoked ATP release into the lumen of the bladder and that luminal release can modulate voiding function.

Actin and Cytokeratin in Superficial Transitional Epithelial Cells of the Rabbit Urinary Bladder: A Confocal and Electron Microscopic Study.

Transitional epithelial cells undergo dynamic morphological alterations during the contraction-expansion cycle in the mammalian urinary bladder. In this study, the localization of two major cytoskeletal elements, actin and cytokeratin, was examined by fluorescence and electron microscopic methods to elucidate the relationship of these components in the transitional epithelial cells of non-distended bladders. Using phalloidin-FITC and confocal laser scanning microscopy (CLSM), a strong staining for filamentous actin was observed at subplasmalemmal regions of the superficial cells. Cytoplasmic regions of these cells were characterized by punctate regions of staining that increased at sites of cell-cell contact. Ultrastructural observations using immunogold and heavy meromyosin (HMM) labelling techniques for detecting actin filaments revealed a rich actin filament network in superficial cells most notably in the subplasmalemmal regions. These filaments occurred in orientations that were both parallel and perpendicular relative to the surface membrane. Intermediate and basal cells contained a less dense network of filamentous actin in comparison to superficial cells. Immunolabelling for cytokeratin 18 revealed abundant thread-like filaments coursing throughout the cytoplasm and making contact with the plasmalemma in superficial cells. By electron microscopy, the cytokeratin filaments formed a dense interlacing network arranged into bundles that interconnected with membrane-bound structures. These observations indicate that actin and cytokeratin are major cytoskeletal elements of transitional epithelial cells and that they are related to the configurational alternations of transitional epithelial cell borders and their contents. It is postulated that these proteins stabilize and support the membrane of superficial cells from hydrostatic pressure within the bladder.