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Tuttle T, McClintock D, Roccabianca S. Effects of swelling and anatomical location on the viscoelastic behavior of the porcine urinary bladder wall. J Mech Behav Biomed Mater 2023; 143:105926. [PMID: 37269604 DOI: 10.1016/j.jmbbm.2023.105926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/18/2023] [Accepted: 05/21/2023] [Indexed: 06/05/2023]
Abstract
The ability of the urinary bladder to perform its physiological function depends largely on its mechanical characteristics. Understanding the mechanics of this tissue is crucial to the development of accurate models of not just this specific organ, but of the pelvic floor overall. In this study, we tested porcine bladder to identify variations in the tissue's viscoelastic characteristics associated with anatomical locations and swelling. We investigated this relationship using a series of stress-relaxation experiments as well as a modified Maxwell-Wiechert model to aid in the interpretation of the experimental data. Our results highlight that tissue located near the neck of the bladder presents significantly different viscoelastic characteristics than the body of the organ. This supports what was previously observed and is a valuable contribution to the understanding of the location-specific properties of the bladder. We also tested the effect of swelling, revealing that the bladder's viscoelastic behavior is mostly independent of solution osmolarity in hypoosmotic solutions, but the use of a hyperosmotic solution can significantly affect its behavior. This is significant, since several urinary tract pathologies can lead to chronic inflammation and disrupt the urothelial barrier causing increased urothelial permeability, thus subjecting the bladder wall to non-physiologic osmotic challenge.
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Affiliation(s)
- Tyler Tuttle
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA
| | - Dillon McClintock
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA.
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2
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Saxena P, Broemer E, Herrera GM, Mingin GC, Roccabianca S, Tykocki NR. Compound 48/80 increases murine bladder wall compliance independent of mast cells. Sci Rep 2023; 13:625. [PMID: 36635439 PMCID: PMC9837046 DOI: 10.1038/s41598-023-27897-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
A balance between stiffness and compliance is essential to normal bladder function, and changes in the mechanical properties of the bladder wall occur in many bladder pathologies. These changes are often associated with the release of basic secretagogues that in turn drive the release of inflammatory mediators from mast cells. Mast cell degranulation by basic secretagogues is thought to occur by activating an orphan receptor, Mas-related G protein-coupled receptor B2 (Mrgprb2). We explored the effects of the putative mast cell degranulator and Mrgprb2 agonist Compound 48/80 on urinary bladder wall mechanical compliance, smooth muscle contractility, and urodynamics, and if these effects were mast cell dependent. In wild-type mice, Mrgprb2 receptor mRNA was expressed in both the urothelium and smooth muscle layers. Intravesical instillation of Compound 48/80 decreased intermicturition interval and void volume, indicative of bladder overactivity. Compound 48/80 also increased bladder compliance while simultaneously increasing the amplitude and leading slope of transient pressure events during ex vivo filling and these effects were inhibited by the Mrgprb2 antagonist QWF. Surprisingly, all effects of Compound 48/80 persisted in mast cell-deficient mice, suggesting these effects were independent of mast cells. These findings suggest that Compound 48/80 degrades extracellular matrix and increases urinary bladder smooth muscle excitability through activation of Mrgprb2 receptors located outside of mast cells. Thus, the pharmacology and physiology of Mrgprb2 in the urinary bladder is of potential interest and importance in terms of treating lower urinary tract dysfunction.
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Affiliation(s)
- Pragya Saxena
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, USA
| | - Eli Broemer
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Gerald M Herrera
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Gerald C Mingin
- Division of Urology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, USA.
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Maddra KM, Li R, Nagle AS, Klausner AP, Speich JE. Repeatability of Ultrasound-Defined Bladder Shape Metrics in Healthy Volunteers. Res Rep Urol 2022; 14:185-192. [PMID: 35572816 PMCID: PMC9091689 DOI: 10.2147/rru.s351347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/16/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Patients and Methods Results Conclusion
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Affiliation(s)
- Kaitlyn M Maddra
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Rui Li
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
- Correspondence: John E Speich, Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA, Tel +1 804 827 7036, Fax +1 804 827 7030, Email
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Zwaans BMM, Grobbel M, Carabulea AL, Lamb LE, Roccabianca S. Increased extracellular matrix stiffness accompanies compromised bladder function in a murine model of radiation cystitis. Acta Biomater 2022; 144:221-229. [PMID: 35301146 PMCID: PMC9100859 DOI: 10.1016/j.actbio.2022.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 02/14/2022] [Accepted: 03/08/2022] [Indexed: 11/30/2022]
Abstract
Radiation cystitis, a long-term bladder defect due to pelvic radiation therapy, results in lower urinary tract symptoms, such as urinary frequency and nocturia, suggestive of compromised bladder compliance. The goal of this study was to identify alterations to the mechanical behavior of the urinary bladder extracellular matrix of a murine model of radiation cystitis, at 3 and 6 months after radiation exposure. The results of this study demonstrated that the extracellular matrix of irradiated bladders was significantly less distensible when compared to age matching controls. These findings coincided with functional bladder changes, including increased number of voids and decreased voided volume. Both mechanical and functional changes were apparent at 3 months post-irradiation and were statistically significant at 6 months, demonstrating the progressive nature of radiation cystitis. Overall, the results of this study indicate that irradiation exposure changes both the mechanical and physiological properties of the bladder. STATEMENT OF SIGNIFICANCE: In humans, radiation cystitis results in lower urinary tract symptoms, such as urinary frequency and nocturia, suggestive of compromised bladder compliance. This pathology can significantly affect recovery and quality of life for cancer survivors. Gaining knowledge about how alterations to the mechanical behavior of the urinary bladder extracellular matrix can affect urinary function will have a significant impact on this population. The results of this study demonstrated that the extracellular matrix of irradiated bladders was significantly less distensible when compared to age matching controls, in a mouse model of radiation cystitis. These findings were accompanied by functional voiding changes, including increased number of voids and decreased voided volume. The results of this study uncovered that irradiation exposure changes the mechanical and physiological properties of the bladder.
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Affiliation(s)
- Bernadette M M Zwaans
- Department of Urology, Beaumont Health System, Royal Oak, MI, United States; Oakland University William Beaumont School of Medicine, Rochester, MI, United States
| | - Marissa Grobbel
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, United States
| | | | - Laura E Lamb
- Department of Urology, Beaumont Health System, Royal Oak, MI, United States; Oakland University William Beaumont School of Medicine, Rochester, MI, United States
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, United States.
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Tuttle TG, Lujan HL, Tykocki NR, DiCarlo SE, Roccabianca S. Remodeling of extracellular matrix in the urinary bladder of paraplegic rats results in increased compliance and delayed fiber recruitment 16 weeks after spinal cord injury. Acta Biomater 2022; 141:280-289. [PMID: 35032719 PMCID: PMC8898290 DOI: 10.1016/j.actbio.2022.01.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/17/2021] [Accepted: 01/07/2022] [Indexed: 01/21/2023]
Abstract
The ability of the urinary bladder to maintain low intravesical pressures while storing urine is key in ensuring proper organ function and highlights the key role that tissue mechanics plays in the lower urinary tract. Loss of supraspinal neuronal connections to the bladder after spinal cord injury can lead to remodeling of the structure of the bladder wall, which may alter its mechanical characteristics. In this study, we investigate if the morphology and mechanical properties of the bladder extracellular matrix are altered in rats 16 weeks after spinal cord injury as compared to animals who underwent sham surgery. We measured and quantified the changes in bladder geometry and mechanical behavior using histological analysis, tensile testing, and constitutive modeling. Our results suggest bladder compliance is increased in paraplegic animals 16 weeks post-injury. Furthermore, constitutive modeling showed that increased distensibility was driven by an increase in collagen fiber waviness, which altered the distribution of fiber recruitment during loading. STATEMENT OF SIGNIFICANCE: The ability of the urinary bladder to store urine under low pressure is key in ensuring proper organ function. This highlights the important role that mechanics plays in the lower urinary tract. Loss of control of neurologic connection to the bladder from spinal cord injury can lead to changes of the structure of the bladder wall, resulting in altered mechanical characteristics. We found that the bladder wall's microstructure in rats 16 weeks after spinal cord injury is more compliant than in healthy animals. This is significant since it is the longest time post-injury analyzed, to date. Understanding the extreme remodeling capabilities of the bladder in pathological conditions is key to inform new possible therapies.
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Affiliation(s)
- Tyler G Tuttle
- Michigan State University, Department of Mechanical Engineering, 428 S. Shaw Lane, Rm 2555, East Lansing, MI 48824, United States
| | - Heidi L Lujan
- Michigan State University, Department of Physiology, 567 Wilson Rd., Rm 2201, East Lansing, MI 48824, United States
| | - Nathan R Tykocki
- Michigan State University, Department of Pharmacology and Toxicology, 1355 Bogue St., B436 Life Science Building, East Lansing, MI 48824, United States
| | - Stephen E DiCarlo
- Michigan State University, Department of Physiology, 567 Wilson Rd., Rm 2201, East Lansing, MI 48824, United States
| | - Sara Roccabianca
- Michigan State University, Department of Mechanical Engineering, 428 S. Shaw Lane, Rm 2555, East Lansing, MI 48824, United States.
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A Data-Driven Memory-Dependent Modeling Framework for Anomalous Rheology: Application to Urinary Bladder Tissue. FRACTAL AND FRACTIONAL 2021. [DOI: 10.3390/fractalfract5040223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We introduce a data-driven fractional modeling framework for complex materials, and particularly bio-tissues. From multi-step relaxation experiments of distinct anatomical locations of porcine urinary bladder, we identify an anomalous relaxation character, with two power-law-like behaviors for short/long long times, and nonlinearity for strains greater than 25%. The first component of our framework is an existence study, to determine admissible fractional viscoelastic models that qualitatively describe linear relaxation. After the linear viscoelastic model is selected, the second stage adds large-strain effects to the framework through a fractional quasi-linear viscoelastic approach for the nonlinear elastic response of the bio-tissue of interest. From single-step relaxation data of the urinary bladder, a fractional Maxwell model captures both short/long-term behaviors with two fractional orders, being the most suitable model for small strains at the first stage. For the second stage, multi-step relaxation data under large strains were employed to calibrate a four-parameter fractional quasi-linear viscoelastic model, that combines a Scott-Blair relaxation function and an exponential instantaneous stress response, to describe the elastin/collagen phases of bladder rheology. Our obtained results demonstrate that the employed fractional quasi-linear model, with a single fractional order in the range α = 0.25–0.30, is suitable for the porcine urinary bladder, producing errors below 2% without need for recalibration over subsequent applied strains. We conclude that fractional models are attractive tools to capture the bladder tissue behavior under small-to-large strains and multiple time scales, therefore being potential alternatives to describe multiple stages of bladder functionality.
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Li R, Nagle AS, Maddra KM, Vinod N, Prince SA, Tensen SI, Thapa D, Sebastian B, Sethi D, Alattar A, Carucci LR, Klausner AP, Speich JE. Irregular bladder shapes identified in women with overactive bladder: an ultrasound nomogram. AMERICAN JOURNAL OF CLINICAL AND EXPERIMENTAL UROLOGY 2021; 9:367-377. [PMID: 34796252 PMCID: PMC8595087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
In this study, an ultrasound-based bladder shape nomogram was developed using data from women without overactive bladder (OAB) and tested in women with OAB to identify irregular bladder shapes. The goal was development of a nomogram that can ultimately be used for non-invasive identification of a bladder shape-associated OAB phenotype. Transabdominal 3-dimensional (3D) bladder ultrasound images were collected at 1-minute intervals during urodynamics studies and at 5-10-minute intervals during oral hydration studies. These prospective studies enrolled women with and without OAB based on International Consultation on Incontinence questionnaire on OAB (ICIq-OAB) question 5a (OAB 5a≥2, without OAB 5a<2). Bladder perimeters were manually traced and refined using GE 4D-View software. Nomograms for the transverse, sagittal and coronal perimeter-volume relationships were developed for women without OAB. A power model was used to approximate upper and lower nomogram bounds with 95% confidence intervals. Nomograms were tested using data from women with OAB, and each participant was classified as having an irregular bladder shape based on the number of perimeter values outside the nomogram bounds. Nomograms were developed using 533 images from 27 women without OAB (14 from urodynamics and 13 from hydration studies) and were tested using 264 images from 24 women with OAB (16 urodynamics and 8 hydration). The sagittal perimeter nomogram provided the best results, with irregular sagittal perimeters identified in 6/24 (25%) women with OAB and 0/27 (0%) without OAB. An irregular sagittal perimeter was significantly associated with OAB (P<0.05). Ultrasound-based nomograms may enable feasible, non-invasive identification of a subgroup of women with bladder shape-associated OAB.
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Affiliation(s)
- Rui Li
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
| | - Kaitlyn M Maddra
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Naomi Vinod
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Suzanne A Prince
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
| | - Sarah I Tensen
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
| | - Devina Thapa
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Blessan Sebastian
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Dhruv Sethi
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Abraham Alattar
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
| | - Laura R Carucci
- Department of Radiology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - Adam P Klausner
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of MedicineRichmond 23298, VA, USA
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of EngineeringRichmond 23284, VA, USA
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Swavely NR, Speich JE, Klausner AP. Artifacts and abnormal findings may limit the use of asymptomatic volunteers as controls for studies of multichannel urodynamics. Minerva Urol Nephrol 2021; 73:655-661. [PMID: 32638575 PMCID: PMC9112542 DOI: 10.23736/s2724-6051.20.03838-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Multichannel urodynamics is the gold standard for the evaluation of lower urinary tract symptoms (LUTS). When performing studies to validate new adjuncts to urodynamic testing with control patients undergoing urodynamic investigation, there is difficulty in the interpretation of urodynamic results in the asymptomatic patient due to artifacts and the invasive nature of the procedure. The purpose of this investigation was to examine urodynamics in asymptomatic volunteers in order to better understand the role of control participants in urodynamic research studies. METHODS Asymptomatic volunteers with no LUTS were recruited to undergo standard urodynamic testing as a comparison group in a study evaluating novel urodynamic techniques. To be eligible, participants had to report no LUTS, score ≤1 on all symptom questions of the International Consultation on Incontinence Questionnaire Overactive Bladder Module (ICIq-OAB) survey, have no medical conditions or to undergo any medications that affect bladder function. The urodynamics was done according to ICS standards. All tracings were evaluated by an expert neuro-urologist. Data were analyzed categorically for the presence or absence of low compliance (<30 mL/cmH20), detrusor overactivity, bladder outlet obstruction (Bladder Outlet Obstruction Index [BOOI]>40), weak contractility (bladder contractility index [BCI]<100), straining to void, poorly sustained detrusor contraction, uncoordinated EMG activity, and intermittent flow. RESULTS A total of 24 participants completed the study including 10 men and 14 women. All participants had at least 1 urodynamic abnormality/artifact with an average of 4.43±1.28 abnormalities/participant. The most common abnormalities included uncoordinated electromyography (EMG) activity (87.50%), straining to void (79.17%), and intermittent flow (70.83%). There were no significant differences for sex, age, Body Mass Index. CONCLUSIONS This study demonstrated that healthy, asymptomatic volunteers have high rates of abnormal urodynamic findings, suggesting that asymptomatic participants are not the ideal controls in research studies that involve urodynamic testing.
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Affiliation(s)
- Natalie R Swavely
- Virginia Commonwealth University School of Medicine, Division of Urology, Department of Surgery, Richmond, VA, USA
| | - John E Speich
- Virginia Commonwealth University School of Engineering, Department of Mechanical and Nuclear Engineering, Richmond, VA, USA
| | - Adam P Klausner
- Virginia Commonwealth University School of Medicine, Division of Urology, Department of Surgery, Richmond, VA, USA -
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Regulation of bladder dynamic elasticity: a novel method to increase bladder capacity and reduce pressure using pulsatile external compressive exercises in a porcine model. Int Urol Nephrol 2021; 53:1819-1825. [PMID: 34212270 DOI: 10.1007/s11255-021-02863-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/11/2021] [Indexed: 12/27/2022]
Abstract
PURPOSE Dynamic elasticity is a biomechanical property of the bladder in which muscle compliance can be acutely adjusted through passive stretches and reversed with active contractions. The aim of this study was to determine if manipulating dynamic elasticity using external compression could be used as a novel method to acutely increase bladder capacity and reduce bladder pressure in a porcine model. METHODS Ex vivo experiment: bladders underwent continuous or pulsatile compression after establishing a reference pressure at bladder capacity. Bladders were then filled back to the reference pressure to determine if capacity could be acutely increased. In-vivo experiments: bladders underwent five cycles of pulsatile external compression with ultrasound confirmation. Pre and post-compression pressures were measured, and pressure was measured again 10 min post-compression. RESULTS Ex vivo experiment: pulsatile compression demonstrated increased bladder capacity by 16% (p = 0.01). Continuous compression demonstrated increased capacity by 9% (p < 0.03). Comparison of pulsatile to continuous compression showed that the pulsatile method was superior (p = 0.03). In-vivo experiments: pulsatile external compression reduced bladder pressure by 19% (p < 0.00001) with a return to baseline 10 min post-compression. CONCLUSIONS These results suggest that regulation of bladder dynamic elasticity achieved with external compression can acutely decrease bladder pressure and increase bladder capacity. Pulsatile compression was found to be more effective as compared to continuous compression. These results highlight the clinical potential for use of non-invasive pulsatile compression as a therapeutic technique to increase bladder capacity, decrease bladder pressure, and reduce the symptoms of urinary urgency.
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Trostorf R, Morales-Orcajo E, Siebert T, Böl M. Location- and layer-dependent biomechanical and microstructural characterisation of the porcine urinary bladder wall. J Mech Behav Biomed Mater 2020; 115:104275. [PMID: 33360487 DOI: 10.1016/j.jmbbm.2020.104275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 11/04/2020] [Accepted: 12/12/2020] [Indexed: 02/07/2023]
Abstract
The knowledge of the mechanical properties of the urinary bladder wall helps to explain its storage and micturition functions in health and disease studies; however, these properties largely remain unknown, especially with regard to its layer-specific characteristics and microstructure. Consequently, this study entails the assessment of the layer-specific differences in the mechanical properties and microstructure of the bladder wall, especially during loading. Accordingly, ninety-two (n=92) samples of porcine urinary bladder walls were mechanically and histologically analysed. Generally, the bladder wall and different tissue layers exhibit a non-linear stress-stretch relationship. In this study, the load transfer mechanisms were not only associated with the wavy structure of muscular and mucosal layers, but also with the entire bladder wall microstructure. Contextually, an interplay between the mucosal and muscular layers could be identified. Therefore, depending on the region and direction, the mucosal layer exhibited a stiffer mechanical response to equi-biaxial loading than that offered by the muscular layer when deformed to stretch levels higher than λ=1.6 to λ=2.2. For smaller stretches, the mucosal layer evinces no significant mechanical reaction, while the muscular layer bears the load. Owing to the orientation of its muscle fibres, the muscular layer shows an increased degree of anisotropy compared to the mucosal layer. Furthermore, the general incompressibility assumption is analysed for different layers by measuring the change in thickness during loading, which indicated a small volume loss.
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Affiliation(s)
- Robin Trostorf
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Enrique Morales-Orcajo
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany
| | - Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart D-70569, Germany
| | - Markus Böl
- Institute of Mechanics and Adaptronics, Technische Universität Braunschweig, Braunschweig D-38106, Germany.
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11
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Cullingsworth ZE, Klausner AP, Li R, Nagle AS, Carroll AW, Roseman JT, Speich JE. Comparative-fill urodynamics in individuals with and without detrusor overactivity supports a conceptual model for dynamic elasticity regulation. Neurourol Urodyn 2019; 39:707-714. [PMID: 31856359 DOI: 10.1002/nau.24255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 12/06/2019] [Indexed: 12/17/2022]
Abstract
AIMS Dynamic elasticity was previously identified in individuals with overactive bladder (OAB) using comparative-fill urodynamics (UD) and is a biomechanical mechanism for acutely regulating detrusor wall tension. On the basis of this data, a conceptual model of dynamic elasticity regulation mediated through a balance of passive mechanisms and active contractions was constructed. The present study tested this model by determining whether individuals with detrusor overactivity (DO) exhibit less dynamic elasticity than individuals without DO. METHODS Individuals with and without urgency based on International Consultation on Incontinence Questionnaire-OAB surveys were prospectively enrolled in a comparative-fill UD study. An initial fill defined the presence or absence of DO and determined cystometric capacity. Three additional fills were employed with either passive emptying via a catheter or active voiding. To identify dynamic elasticity, average filling pressures (Pves ) were compared for fill 1 (before strain softening), fill 2 (after strain softening), and fill 3 (after active void). A dynamic elasticity index was defined. RESULTS From 28 participants, those without DO showed decreased Pves during filling after strain softening and restored Pves during filling following active voiding, revealing dynamic elasticity. Participants with DO did not show dynamic elasticity. A dynamic elasticity index less than 1.0 cmH2 O/40% capacity was identified in 2 out of 13 participants without DO and 9 out of 15 with DO, revealing a significant association between DO and reduced/absent dynamic elasticity (P = .024). CONCLUSIONS This study supports a conceptual model for dynamic elasticity, a mechanism to acutely regulate detrusor wall tension through a balance of competing active contractile and passive strain mechanisms. Improved understanding of this mechanistic model may help us to identify novel treatment strategies for OAB.
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Affiliation(s)
- Zachary E Cullingsworth
- Department of Mechanical and Nuclear Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Adam P Klausner
- Division of Urology, Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Rui Li
- Department of Mechanical and Nuclear Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Ashley W Carroll
- Department of Obstetrics and Gynecology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - John T Roseman
- Division of Urology, Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, College of Engineering, Virginia Commonwealth University, Richmond, Virginia
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12
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Sheen D, Kolli H, Nagle AS, Cullingsworth Z, Vinod NN, Naimi HA, De Wachter SG, Mazzeo SE, Stothers L, Speich JE, Klausner AP. Validation of a real-time bladder sensation meter during oral hydration in healthy adults: Repeatability and effects of fill rate and ultrasound probe pressure. Low Urin Tract Symptoms 2019; 11:224-231. [PMID: 31298501 DOI: 10.1111/luts.12275] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/06/2019] [Accepted: 06/17/2019] [Indexed: 11/26/2022]
Abstract
OBJECTIVES A non-invasive protocol was previously developed using three-dimensional ultrasound and a sensation meter to characterize real-time bladder sensation. This study the protocol by measuring the effects of fill rateand ultrasound probe pressure during oral hydration. METHODS Healthy volunteers with no urinary symptoms (based on International Consultation on Incontinence Questionnaire on Overactive Bladder surveys) were recruited into an oral hydration study. Throughout two complete fill-void cycles, participants drank 2 L Gatorade G2 (The Gatorade Company, Inc., Chicago, Illinois) and used a touch-screen sensation meter to record real-time bladder sensation (0%-100%). The study was repeated three times, once per week (Visits A, B, and C). In Visits A and B, ultrasound was used to measure bladder volume every 5 minutes. Ultrasound was not used in Visit C except at 100% capacity. Volume data from Visit B were used to estimate volumes throughout the fills in Visit C. Sensation-capacity curves were generated for each fill for comparative analysis. RESULTS Ten participants completed three visits (60 total fills). Increased fill rate led to decreased sensation throughout filling, andultrasound probe pressure led to increased sensation. Participants reported higher sensation at low volumes during Fill 1 of Visit A before training with the sensation meter. Sensation curves with intermittent ultrasound showed repeatability for Fill 2 in Visits A and B. Fill rate and ultrasound probe pressure affect real-time bladder sensation during oral hydration. CONCLUSIONS This study demonstrated repeatability of real-time bladder sensation during a two-fill oral hydration protocol with ultrasound.
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Affiliation(s)
- Derek Sheen
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Hiren Kolli
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Zachary Cullingsworth
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Naomi N Vinod
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Hameeda A Naimi
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Stefan G De Wachter
- Department of Urology, University Hospital Antwerpen, Edegem, Belgium.,Department of Urology, University of Antwerpen, Wilrijk, Belgium
| | - Suzanne E Mazzeo
- Department of Psychology, Virginia Commonwealth University, College of Humanities and Sciences, Richmond, Virginia
| | - Lynn Stothers
- Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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13
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Swavely NR, Speich JE, Stothers L, Klausner AP. New Diagnostics for Male Lower Urinary Tract Symptoms. CURRENT BLADDER DYSFUNCTION REPORTS 2019; 14:90-97. [PMID: 31938079 PMCID: PMC6959483 DOI: 10.1007/s11884-019-00511-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Lower urinary tract symptoms (LUTS) is a common constellation of symptoms that affect the aging male population with an astonishing prevalence. New technology and new uses of established technology are being used to help further evaluate LUTS in the male population and help guide treatment options. This review focuses on the developments and future directions in diagnostic modalities for evaluation of male LUTS, focusing on evaluation of both the filling and voiding phases of micturition. RECENT FINDINGS New techniques in evaluating the voiding phase include penile cuff test, external pressure sensing condom catheter, ultrasound measurement of detrusor wall thickness, ultrasound measurement of intravesical prostatic protrusion, doppler ultrasound and NIRS technology. Evaluation of the filling phase is still undergoing much development and requires additional validation studies. The techniques undergoing evaluation include sensation meters during UDS, assessing bladder micromotion and wall rhythm, assessing detrusor wall biomechanics, ultrasound measurement of detrusor wall thickness, pelvic doppler ultrasound, as well as functional brain imaging including fNIRS and fMRI. SUMMARY The development of novel, non-invasive, diagnostic tools have the potential for better evaluation of LUTS with earlier and enhanced treatments. This will likely improve the quality of life for men with LUTS.
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Affiliation(s)
- Natalie R Swavely
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - John E Speich
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA
| | - Lynn Stothers
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA
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14
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Xiao D, Wang Q, Yan H, Lv X, Zhao Y, Zhou Z, Zhang M, Sun Q, Sun K, Li W, Lu M. Adipose-derived stem cells-seeded bladder acellular matrix graft-silk fibroin enhances bladder reconstruction in a rat model. Oncotarget 2017; 8:86471-86487. [PMID: 29156809 PMCID: PMC5689699 DOI: 10.18632/oncotarget.21211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 08/28/2017] [Indexed: 12/20/2022] Open
Abstract
The unfavourable clinical outcomes of host cell-seeded scaffolds for bladder augmentation warrant improved bioactive biomaterials. This study aimed to examine the feasibility of adipose-derived stem cells (ASCs)-seeded bilayer bladder acellular matrix graft (BAMG)-silk fibroin (SF) scaffold in enhancing bladder reconstruction. Sprague Dawley rats were randomly divided into three groups: the BAMG-SF-ASCs group, the acellular BAMG-SF group and the cystotomy group. The BAMG-SF-ASCs group was sampled at 2, 4 and 12 weeks, and compared with the other groups at 12 weeks. In the BAMG-SF-ASCs group, the normal bladder contour was reformed similar to that in the cystotomy group, with abundant urothelium and smooth muscle regeneration, as well as a suitable scaffold degradation speed, and trivial fibrosis and inflammation. The ASCs seeded in BAMG-SF were maintained in the regenerated region during the 12-week experimental period and significantly enhanced the vessel density, nerve regeneration and bladder function compared with acellular BAMG-SF. In addition, the BAMG-SF-ASCs group presented elevated levels of SDF-1α, VEGF and their receptors, with an obvious increase in ERK 1/2 phosphorylation. BAMG-SF is a promising biomaterial for ASCs seeding to facilitate bladder augmentation and demonstrated an enhanced angiogenic potential possibly related to the SDF-1α/CXCR4 pathway via ERK 1/2 activation.
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Affiliation(s)
- Dongdong Xiao
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Qiong Wang
- Department of Urology, The Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Hao Yan
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Xiangguo Lv
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Yang Zhao
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Zhe Zhou
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Ming Zhang
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
| | - Qian Sun
- The State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kang Sun
- The State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wei Li
- The State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Mujun Lu
- Department of Urology and Andrology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China
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15
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Quantification of bladder wall biomechanics during urodynamics: A methodologic investigation using ultrasound. J Biomech 2017; 61:232-241. [PMID: 28835340 DOI: 10.1016/j.jbiomech.2017.07.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 06/20/2017] [Accepted: 07/22/2017] [Indexed: 01/22/2023]
Abstract
Overactive bladder is often characterized by biomechanical changes in the bladder wall, but there is no established method to measure these changes in vivo. The goal of this study was to develop a novel method to determine detrusor wall biomechanical parameters during urodynamics through the incorporation of transabdominal ultrasound imaging. Individuals with overactive bladder (OAB) underwent ultrasound imaging during filling. The fill rate was 10% of the cystometric capacity per minute as determined by an initial fill. Transabdominal ultrasound images were captured in the midsagittal and transverse planes at 1min intervals. Using image data and Pves, detrusor wall tension, stress, and compliance were calculated. From each cross-sectional image, luminal and wall areas along with inner perimeters were measured. In the sagittal and transverse planes, wall tension was calculated as Pves∗luminal area, wall stress as tension/wall area, and strain as the change in perimeter normalized to the perimeter at 10% capacity. Elastic modulus was calculated as stress/strain in the medial-lateral and cranial-caudal directions. Patient-reported fullness sensation was continuously recorded. Data from five individuals with OAB showed that detrusor wall tension, volume, and strain had the highest correlations to continuous bladder sensation of all quantities measured. This study demonstrates how detrusor wall tension, stress, strain, and elastic modulus can be quantified by adding ultrasound imaging to standard urodynamics. This technique may be useful in diagnosing and better understanding the biomechanics involved in OAB and other bladder disorders.
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Xiao D, Wang Q, Yan H, Qin A, Lv X, Zhao Y, Zhang M, Zhou Z, Xu J, Hu Q, Lu M. Comparison of morphological and functional restoration between asymmetric bilayer chitosan and bladder acellular matrix graft for bladder augmentation in a rat model. RSC Adv 2017. [DOI: 10.1039/c7ra07601k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Asymmetric bilayer chitosan promoted bladder reconstruction with enhanced smooth muscle regeneration and angiogenesis, and functional restoration with augmented bladder capacity.
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