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Lau HH, Lai CY, Peng HY, Hsieh MC, Su TH, Lee JJ, Lin TB. Modification of bladder thermodynamics in stress urinary incontinence patients submitted to trans-obturator tape: A retrospective study based on urodynamic assessment. Front Bioeng Biotechnol 2022; 10:912602. [PMID: 36061421 PMCID: PMC9437260 DOI: 10.3389/fbioe.2022.912602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Importance: It needs to be clarified whether trans-obturator tape (TOT)-enhanced urethral resistance could impact the voiding function.Objective: Although TOT has been well-recognized for enhancing urethral resistance to restore continence in stress urinary incontinence (SUI) patients, whether the bladder’s voiding functions adapt to the TOT-enhanced resistance has not been adequately investigated. This study thereby aimed to investigate whether TOT impacts the bladder’s thermodynamic efficacy during the voiding phase.Design: A retrospective analysis of urodynamics performed before and after TOT was assessed.Setting: A tertiary referral hospital in Taiwan.Participants: A total of 26 female SUI patients who underwent urodynamic investigations before and after TOT.Main outcomes and measures: The area enclosed by the pressure-volume loop (Apv), which represents the work performed by the bladder during voiding, in a pressure-volume analysis established by plotting the detrusor pressure versus intra-vesical volume was retrospectively analyzed. Paired Student’s t-tests were employed to assess the difference in values before and after the operation. Significance in difference was set at p < 0.05.Results: TOT increased Apv in 20 of 26 (77%) patients and significantly increased the mean Apv compared to the preoperative control (2.17 ± 0.18 and 1.51 ± 0.13 × 103 cmH2O-ml, respectively p < 0.01). TOT also increased the mean urethral resistance (1.03 ± 0.30 vs. 0.29 ± 0.05 cmH2O-sec/ml, p < 0.01) and mean voiding pressure (25.87 ± 1.72 and 19.30 ± 1.98 cmH2O p < 0.01) but did not affect the voided volume and voiding time. Moreover, the TOT-induced Apv increment showed a moderate correlation with the changes in urethral resistance and voiding pressure (both r > 0.5) but no correlation with changes in voided volume or voiding time. It is remarkable that the TOT-induced urethral resistance increment showed a strong correlation with changes in voiding pressure (r > 0.7).Conclusion and Relevance: The bladder enhances thermodynamic efficacy by adapting the voiding mechanism to increased urethral resistance caused by TOT. Further studies with higher case series and longer follow-ups should assess whether this effect could be maintained over time or expire in a functional detrusor decompensation, to define diagnostic criteria that allow therapeutic interventions aimed at its prevention during the follow-up.Clinical Trial Registration: (clinicaltrials.gov), identifier (NCT05255289)
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Affiliation(s)
- Hui-Hsuan Lau
- Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
- Department of Nursing, Mackay Junior College of Medicine, Nursing and Management, Taipei, Taiwan
- Department of Medicine, MacKay Medical College, Taipei, Taiwan
| | - Cheng-Yuan Lai
- Institute of Biomedical Sciences, MacKay Medical College, New Taipei, Taiwan
| | - Hsien-Yu Peng
- Department of Medicine, MacKay Medical College, Taipei, Taiwan
| | - Ming-Chun Hsieh
- Department of Medicine, MacKay Medical College, Taipei, Taiwan
| | - Tsung-Hsien Su
- Division of Urogynecology, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan
- Department of Nursing, Mackay Junior College of Medicine, Nursing and Management, Taipei, Taiwan
- Department of Medicine, MacKay Medical College, Taipei, Taiwan
| | - Jie-Jen Lee
- Department of Medicine, MacKay Medical College, Taipei, Taiwan
- Department of Surgery, Mackay Memorial Hospital, Taipei, Taiwan
| | - Tzer-Bin Lin
- Institute of New Drug Development, College of Medicine, China Medical University, Taichung, Taiwan
- Cell Physiology and Molecular Image Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- *Correspondence: Tzer-Bin Lin,
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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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Balthazar A, Cullingsworth ZE, Nandanan N, Anele U, Swavely NR, Speich JE, Klausner AP. An external compress-release protocol induces dynamic elasticity in the porcine bladder: A novel technique for the treatment of overactive bladder? Neurourol Urodyn 2019; 38:1222-1228. [PMID: 30947371 DOI: 10.1002/nau.23992] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 03/14/2019] [Indexed: 11/11/2022]
Abstract
INTRODUCTION Dynamic elasticity is an acutely regulated bladder material property through which filling and passive emptying produce strain softening, and active voiding restores baseline pressure. The aim of this study was to test the hypothesis that strain softening produced by filling-passive emptying is equivalent to that produced by compression-release in a porcine bladder model. METHODS/MATERIALS Latex balloons and ex vivo perfused pig bladders were used for a series of alternating fill-passive emptying ("Fill") and external compress-release ("Press") protocols. For the Fill protocol balloons/bladders were (1) filled to defined volumes (prestrain softening), (2) filled to capacity to strain soften (reference), and (3) passively emptied to the original volume (poststrain softening). For the Press protocol, balloons/bladders were (1) filled to defined volumes (prestrain softening), (2) externally compressed to reference pressure and then released for five cycles (poststrain softening). After each protocol, bladders were voided with high-KCl buffer to induce "active" voiding. RESULTS In both balloons and porcine bladder, both the Fill and Press protocols produced significant strain softening (P < 0.05) and poststrain softening pressures were not different for Fill and Press protocols (P > 0.05), indicating a similar degree of strain softening with both methods. CONCLUSIONS Repeated external compression can induce bladder strain softening similar to filling and passive emptying. This technique may represent a means to acutely regulate bladder compliance and potentially be used as a mechanical treatment for urinary urgency.
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Affiliation(s)
- Andrea Balthazar
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Zachary E Cullingsworth
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Naveen Nandanan
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Uzoma Anele
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Natalie R Swavely
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - 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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Drake MJ, Fry CH, Hashitani H, Kirschner-Hermanns R, Rahnama'i MS, Speich JE, Tomoe H, Kanai AJ, McCloskey KD. What are the origins and relevance of spontaneous bladder contractions? ICI-RS 2017. Neurourol Urodyn 2018; 37:S13-S19. [PMID: 29360173 DOI: 10.1002/nau.23485] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/14/2017] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Storage phase bladder activity is a counter-intuitive observation of spontaneous contractions. They are potentially an intrinsic feature of the smooth muscle, but interstitial cells in the mucosa and the detrusor itself, as well as other muscular elements in the mucosa may substantially influence them. They are identified in several models explaining lower urinary tract dysfunction. METHODS A consensus meeting at the International Consultation on Incontinence Research Society (ICI-RS) 2017 congress considered the origins and relevance of spontaneous bladder contractions by debating which cell type(s) modulate bladder spontaneous activity, whether the methodologies are sufficiently robust, and implications for healthy and abnormal lower urinary tract function. RESULTS The identified research priorities reflect a wide range of unknown aspects. Cellular contributions to spontaneous contractions in detrusor smooth muscle are still uncertain. Accordingly, insight into the cellular physiology of the bladder wall, particularly smooth muscle cells, interstitial cells, and urothelium, remains important. Upstream influences, such as innervation, endocrine, and paracrine factors, are particularly important. The cellular interactions represent the key understanding to derive the integrative physiology of organ function, notably the nature of signalling between mucosa and detrusor layers. Indeed, it is still not clear to what extent spontaneous contractions generated in isolated preparations mirror their normal and pathological counterparts in the intact bladder. Improved models of how spontaneous contractions influence pressure generation and sensory nerve function are also needed. CONCLUSIONS Deriving approaches to robust evaluation of spontaneous contractions and their influences for experimental and clinical use could yield considerable progress in functional urology.
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Affiliation(s)
- Marcus J Drake
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.,Bristol Urological Institute, Southmead Hospital, Bristol, United Kingdom
| | - Christopher H Fry
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Hikaru Hashitani
- Department of Cell Physiology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - Ruth Kirschner-Hermanns
- Neuro-Urology/Urology, University Clinic, Rheinische Friedrich Wilhelms University Bonn and Neurological Rehabilitation Center Godeshöhe, Bonn, Germany
| | | | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Hikaru Tomoe
- Department of Urology and Pelvic Reconstructive Surgery, Tokyo Women's Medical University Medical Center East, Tokyo, Japan
| | - Anthony J Kanai
- Department of Medicine, Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Karen D McCloskey
- Centre for Cancer Research and Cell Biology, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom
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Vince R, Tracey A, Deebel NA, Barbee RW, Speich JE, Klausner AP, Ratz PH. Effects of vesical and perfusion pressure on perfusate flow, and flow on vesical pressure, in the isolated perfused working pig bladder reveal a potential mechanism for the regulation of detrusor compliance. Neurourol Urodyn 2017; 37:642-649. [PMID: 28745836 DOI: 10.1002/nau.23362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/23/2017] [Indexed: 11/06/2022]
Abstract
AIMS Although there is evidence that deficits in bladder blood flow negatively impact bladder function, the effects of vesical, and perfusion pressures on bladder perfusion (perfusate flow), and of perfusate flow on vesical pressure, remain poorly understood. The present study used the isolated perfused working pig bladder model to examine the relationships between blood flow, and vesical and perfusion pressures. METHODS Vesical arteries of pig bladders obtained from a local slaughterhouse were cannulated and perfused with Krebs-Henseleit solution at different pressures, and with carbachol to cause bladder contraction. The urethra of each bladder was cannulated to permit filling (10 mL/min), isovolumetric contraction and emptying. A ureter was cannulated with a pressure sensor to monitor vesical pressure. RESULTS When at rest (50 mL vesical volume), bladder vesical pressure was 8.06 ± 1.5 mmHg and perfusate flow driven by a pressure gradient of 105 mmHg was 22.5 ± 2 mL/min (58.9 ± 7.8 mL/min-100 g). During filling, vesical pressure increased and flow decreased, but not necessarily in-parallel. Perfusate flow decreased transiently during isovolumetric contraction, and flow increased during emptying. A reduction in perfusion pressure from ∼105 to ∼40 mmHg reduced flow from ∼70 to ∼20 mL/min-100g, and reduced flow correlated with reduced vesical pressure. CONCLUSION Perfusate flow is dependent on bladder perfusion pressure, and not necessarily reciprocally dependent on vesical pressure. Vesical pressure is highly sensitive to the level of perfusate flow, which supports the hypothesis that vesical pressure is dependent on the level of detrusor smooth muscle contractile activity (tone), and that compliance is dependent on bladder perfusion.
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Affiliation(s)
- Randy Vince
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Andrew Tracey
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Nicholas A Deebel
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Robert W Barbee
- Departments of Emergency Medicine and Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Adam P Klausner
- Department of Surgery, Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Paul H Ratz
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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Abstract
OBJECTIVES To investigate the effect of changing the bladder filling rate during cystometry in younger (2-3 months) and older (13-14 months) C57BL/6J male mice. METHODS Cystometry was performed on mice under anesthesia. Voiding cycles were established in each mouse at a pump delivery rate of 17 μl/min. After 30 min, the rate was increased sequentially to 25, 33, 41 and 49 μl/min. Each rate was maintained for 30 min. The following cystometric parameters were quantified: peak pressure amplitude, intercontractile interval (ICI), compliance, micturition pressure threshold and voiding efficiency. RESULTS Bladder weights were significantly greater in older mice (42 mg vs. 27 mg, P < 0.01), but functional capacities were not different. The pressure amplitudes did not change as filling rate increased, nor did they differ between the 4-month and 13-month-old males. ICIs were not significantly different between young and mature mice. However, both groups exhibited a non-linear reduction in ICI with increasing filling rate, best described by a power curve (R2 > 0.93). Compliance was higher in the older mice at low filling rates (17 and 25 μl/min) but this difference diminished at higher rates. Compliance decreased with increasing flow rate in a non-linear manner, again with greater effects at low filling rates. Micturition pressure thresholds increased with increasing flow rate in a linear manner and older mice began voiding at higher pressures than younger. Both young and old mice exhibited voiding efficiencies of ~70%. CONCLUSIONS The rate of volume delivery has complex effects on the timing of voiding and compliance. These findings argue for greater standardization of cystometry protocols and further investigation into afferent signaling to higher centers at different filling rates.
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Affiliation(s)
- Alexandra K Kim
- Laboratory of Voiding Dysfunction, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Warren G Hill
- Laboratory of Voiding Dysfunction, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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7
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Habteyes FG, Komari SO, Nagle AS, Klausner AP, Heise RL, Ratz PH, Speich JE. Modeling the influence of acute changes in bladder elasticity on pressure and wall tension during filling. J Mech Behav Biomed Mater 2017; 71:192-200. [PMID: 28343086 DOI: 10.1016/j.jmbbm.2017.02.020] [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: 07/18/2016] [Revised: 02/07/2017] [Accepted: 02/17/2017] [Indexed: 01/22/2023]
Abstract
Tension-sensitive nerves in the bladder wall are responsible for providing bladder sensation. Bladder wall tension, and therefore nerve output, is a function of bladder pressure, volume, geometry and material properties. The elastic modulus of the bladder is acutely adjustable, and this material property is responsible for adjustable preload tension exhibited in human and rabbit detrusor muscle strips and dynamic elasticity revealed during comparative-fill urodynamics in humans. A finite deformation model of the bladder was previously used to predict filling pressure and wall tension using uniaxial tension test data and the results showed that wall tension can increase significantly during filling with relatively little pressure change. In the present study, published uniaxial rabbit detrusor data were used to quantify regulated changes in the elastic modulus, and the finite deformation model was expanded to illustrate the potential effects of elasticity changes on pressure and wall tension during filling. The model demonstrates a shift between relatively flat pressure-volume filling curves, which is consistent with a recent human urodynamics study, and also predicts that dynamic elasticity would produce significant changes in wall tension during filling. The model results support the conclusion that acute regulation of bladder elasticity could contribute to significant changes in wall tension for a given volume that could lead to urgency, and that a single urodynamic fill may be insufficient to characterize bladder biomechanics. The model illustrates the potential value of quantifying wall tension in addition to pressure during urodynamics.
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Affiliation(s)
- Firdaweke G Habteyes
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23284, United States
| | - S Omid Komari
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23284, United States
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23284, United States
| | - Adam P Klausner
- Department of Surgery, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - Rebecca L Heise
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, United States
| | - Paul H Ratz
- Departments of Biochemistry & Molecular Biology and Pediatrics, Virginia Commonwealth University, Richmond, VA 23298, United States
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA 23284, United States.
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8
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Colhoun AF, Klausner AP, Nagle AS, Carroll AW, Barbee RW, Ratz PH, Speich JE. A pilot study to measure dynamic elasticity of the bladder during urodynamics. Neurourol Urodyn 2016; 36:1086-1090. [PMID: 27241067 DOI: 10.1002/nau.23043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 05/10/2016] [Indexed: 11/07/2022]
Abstract
AIMS Previous studies using isolated strips of human detrusor muscle identified adjustable preload tension, a novel mechanism that acutely regulates detrusor wall tension. The purpose of this investigation was to develop a method to identify a correlate measure of adjustable preload tension during urodynamics. METHODS Patients reporting urgency most or all of the time based on ICIq-OAB survey scores were prospectively enrolled in an extended repeat fill-and-empty urodynamics study designed to identify a correlate of adjustable preload tension which we now call "dynamic elasticity." Cystometric capacity was determined during initial fill. Repeat fills to defined percentages of capacity with passive emptying (via syringe aspiration) were performed to strain soften the bladder. A complete fill with active voiding was included to determine whether human bladder exhibits reversible strain softening. RESULTS Five patients completed the extended urodynamics study. Intravesical pressure (pves ) decreased with subsequent fills and was significantly lower during Fill 3 compared to Fill 1 (P = 0.008), demonstrating strain softening. Active voiding after Fill 3 caused strain softening reversal, with pves in Fill 4 returning to the baseline measured during Fill 1 (P = 0.29). Dynamic elasticity, the urodynamic correlate of adjustable preload tension, was calculated as the amount of strain softening (or its reversal) per %capacity (Δaverage pves between fills/Δ%capacity). Dynamic elasticity was lost via repeat passive filling and emptying (strain softening) and regained after active voiding regulated the process (strain softening reversal). CONCLUSIONS Improved understanding of dynamic elasticity in the human bladder could lead to both improved sub-typing and novel treatments of overactive bladder. Neurourol. Urodynam. 36:1086-1090, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Andrew F Colhoun
- Division of Urology/Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Adam P Klausner
- Division of Urology/Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University School of Engineering, Richmond, Virginia
| | - Ashley W Carroll
- Department of Obstetrics and Gynecology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Robert W Barbee
- Departments of Emergency Medicine and Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Paul H Ratz
- Departments of Biochemistry and Molecular Biology and Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University School of Engineering, Richmond, Virginia
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Abstract
Vascular smooth muscle (VSM; see Table 1 for a list of abbreviations) is a heterogeneous biomaterial comprised of cells and extracellular matrix. By surrounding tubes of endothelial cells, VSM forms a regulated network, the vasculature, through which oxygenated blood supplies specialized organs, permitting the development of large multicellular organisms. VSM cells, the engine of the vasculature, house a set of regulated nanomotors that permit rapid stress-development, sustained stress-maintenance and vessel constriction. Viscoelastic materials within, surrounding and attached to VSM cells, comprised largely of polymeric proteins with complex mechanical characteristics, assist the engine with countering loads imposed by the heart pump, and with control of relengthening after constriction. The complexity of this smart material can be reduced by classical mechanical studies combined with circuit modeling using spring and dashpot elements. Evaluation of the mechanical characteristics of VSM requires a more complete understanding of the mechanics and regulation of its biochemical parts, and ultimately, an understanding of how these parts work together to form the machinery of the vascular tree. Current molecular studies provide detailed mechanical data about single polymeric molecules, revealing viscoelasticity and plasticity at the protein domain level, the unique biological slip-catch bond, and a regulated two-step actomyosin power stroke. At the tissue level, new insight into acutely dynamic stress-strain behavior reveals smooth muscle to exhibit adaptive plasticity. At its core, physiology aims to describe the complex interactions of molecular systems, clarifying structure-function relationships and regulation of biological machines. The intent of this review is to provide a comprehensive presentation of one biomachine, VSM.
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Affiliation(s)
- Paul H Ratz
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA
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10
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Colhoun AF, Speich JE, Dolat MT, Habibi JR, Guruli G, Ratz PH, Barbee RW, Klausner AP. Acute length adaptation and adjustable preload in the human detrusor. Neurourol Urodyn 2015; 35:792-7. [DOI: 10.1002/nau.22820] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 06/01/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Andrew F. Colhoun
- Department of Surgery/Division of Urology; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - John E. Speich
- Department of Mechanical and Nuclear Engineering; Virginia Commonwealth University School of Engineering; Richmond Virginia
| | - MaryEllen T. Dolat
- Department of Surgery/Division of Urology; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - Joseph R. Habibi
- Department of Surgery/Division of Urology; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - Georgi Guruli
- Department of Surgery/Division of Urology; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - Paul H. Ratz
- Departments of Biochemistry and Pediatrics; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - Robert W. Barbee
- Department of Emergency Medicine; Virginia Commonwealth University School of Medicine; Richmond Virginia
| | - Adam P. Klausner
- Department of Surgery/Division of Urology; Virginia Commonwealth University School of Medicine; Richmond Virginia
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11
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Komari SO, Headley PC, Klausner AP, Ratz PH, Speich JE. Evidence for a common mechanism for spontaneous rhythmic contraction and myogenic contraction induced by quick stretch in detrusor smooth muscle. Physiol Rep 2013; 1:e00168. [PMID: 24400167 PMCID: PMC3871480 DOI: 10.1002/phy2.168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 10/28/2013] [Accepted: 10/29/2013] [Indexed: 11/23/2022] Open
Abstract
Detrusor smooth muscle exhibits myogenic contraction in response to a quick stretch (QS) as well as spontaneous rhythmic contraction (SRC); however, whether the same population of actomyosin crossbridges with a common regulatory mechanism is responsible for these two types of contraction has not been determined. Detrusor strips from New Zealand white rabbit bladders were allowed to develop SRC at a reference muscle length (Lref), or rhythmic contraction (RC) was induced with tetraethylammonium (TEA). Multiple 10-msec stretches of 15% Lref were then imposed at Lref randomly during the rhythm cycle, and the nadir-to-peak (NTP) tension amplitude of the resulting myogenic contraction was measured. The amplitude and period of the rhythm cycle were measured prior to each QS. NTP was larger when a QS was imposed during a portion the cycle when tension was smaller (n = 3 each SRC and TEA-induced RC). These data suggest that when the rhythmic mechanism was mostly inactive and tension was near a minimum, a larger portion of a shared population of crossbridges was available to produce a myogenic response to a QS. Rho kinase, cyclooxygenase-1, and cyclooxygenase-2 inhibitors (H-1152, SC-560, and NS-398) affected SRC amplitude and NTP amplitude following a QS to the same degree (n = 3 each drug), providing additional evidence to support the hypothesis that a common mechanism is responsible for SRC and myogenic contraction due to QS. If a common mechanism exists, then QS is a potential mechanical probe to study SRC regulation and its alteration in overactive bladder.
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Affiliation(s)
- S Omid Komari
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University Richmond, Virginia, 23284
| | - Patrick C Headley
- Department of Biomedical Engineering, Virginia Commonwealth University Richmond, Virginia, 23284
| | - Adam P Klausner
- Department of Surgery, Virginia Commonwealth University Richmond, Virginia, 23298
| | - Paul H Ratz
- Departments of Biochemistry & Molecular Biology and Pediatrics, Virginia Commonwealth University Richmond, Virginia, 23298
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University Richmond, Virginia, 23284
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12
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Byrne MD, Klausner AP, Speich JE, Southern JB, Habibi JR, Ratz PH. Fourier transform analysis of rabbit detrusor autonomous contractions reveals length dependent increases in tone and slow wave development at long lengths. J Urol 2013; 190:334-40. [PMID: 23485511 DOI: 10.1016/j.juro.2013.02.071] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2013] [Indexed: 11/19/2022]
Abstract
PURPOSE Bladder wall muscle (detrusor) develops low amplitude rhythmic contractions. Low amplitude rhythmic contraction activity is increased in detrusor from patients with overactive bladder. In this in vitro study we used fast Fourier transforms to assess the length dependence of low amplitude rhythmic contraction components. MATERIALS AND METHODS Rabbit detrusor strips were placed in a muscle bath between 2 clips to adjust length and record isometric tension. Tissues stretched from 70% to 130% of a reference muscle length at 10% increments were allowed to develop low amplitude rhythmic contractions at each length for 20 minutes. Low amplitude rhythmic contraction data were analyzed using fast Fourier transforms and represented by a frequency rather than a time spectrum. RESULTS Based on fast Fourier transform analysis summarized by signal peaks within specific frequency ranges, rabbit low amplitude rhythmic contraction waveforms were divided into 1 tonic and 2 phasic components, defined as A0 + A1F1 + A2F2, where A0 is a length dependent basal tonic component that increases linearly, A1F1 is a slow wave with a length dependent specific amplitude (A1) and a length independent constant frequency (F1) of approximately 11.2 Hz, and A2F2 is a fast wave with a length dependent amplitude (A2) and frequency (F2) of approximately 0.03 Hz. CONCLUSIONS Fast Fourier transform analysis revealed that rabbit low amplitude rhythmic contractions consist of a basal tonic component plus 2 phasic components. The amplitude of all 3 components was length dependent. The frequency of the fast component was not length dependent and the slow component was absent at short muscle lengths, developing only at muscle lengths beyond that producing a maximum active contraction.
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Affiliation(s)
- Michael D Byrne
- Division of Urology, Department of Surgery, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0118, USA
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