1
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Bersi MR, Dickerson DA, Roccabianca S. Special Section: Advancing Inclusivity in Biomechanical Engineering Research. J Biomech Eng 2024; 146:060301. [PMID: 38607570 DOI: 10.1115/1.4065310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 04/10/2024] [Indexed: 04/13/2024]
Affiliation(s)
- Matthew R Bersi
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130
| | - Darryl A Dickerson
- Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33199
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI 48824
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2
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Hennig G, Saxena P, Broemer E, Herrera GM, Roccabianca S, Tykocki NR. Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system. Biomech Model Mechanobiol 2023; 22:1685-1695. [PMID: 37249760 PMCID: PMC10511590 DOI: 10.1007/s10237-023-01727-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 05/10/2023] [Indexed: 05/31/2023]
Abstract
Optimal bladder compliance is essential to urinary bladder storage and voiding functions. Calculated as the change in filling volume per change in pressure, bladder compliance is used clinically to characterize changes in bladder wall biomechanical properties that associate with lower urinary tract dysfunction. But because this method calculates compliance without regard to wall structure or wall volume, it gives little insight into the mechanical properties of the bladder wall during filling. Thus, we developed Pentaplanar Reflected Image Macroscopy (PRIM): a novel ex vivo imaging method to accurately calculate bladder wall stress and stretch in real time during bladder filling. The PRIM system simultaneously records intravesical pressure, infused volume, and an image of the bladder in five distinct visual planes. Wall thickness and volume were then measured and used to calculate stress and stretch during filling. As predicted, wall stress was nonlinear; only when intravesical pressure exceeded ~ 15 mmHg did bladder wall stress rapidly increase with respect to stretch. This method of calculating compliance as stress vs stretch also showed that the mechanical properties of the bladder wall remain similar in bladders of varying capacity. This study demonstrates how wall tension, stress and stretch can be measured, quantified, and used to accurately define bladder wall biomechanics in terms of actual material properties and not pressure/volume changes. This method is especially useful for determining how changes in bladder biomechanics are altered in pathologies where profound bladder wall remodeling occurs, such as diabetes and spinal cord injury.
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Affiliation(s)
- Grant Hennig
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Pragya Saxena
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, 48824, USA
| | - Eli Broemer
- Department of Mechanical Engineering, Michigan State University College of Engineering, East Lansing, MI, 48824, USA
| | - Gerald M Herrera
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University College of Engineering, East Lansing, MI, 48824, USA
| | - Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, 48824, USA.
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3
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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4
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Protasi F, Girolami B, Roccabianca S, Rossi D. Store-operated calcium entry: From physiology to tubular aggregate myopathy. Curr Opin Pharmacol 2023; 68:102347. [PMID: 36608411 DOI: 10.1016/j.coph.2022.102347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 11/30/2022] [Accepted: 12/04/2022] [Indexed: 01/06/2023]
Abstract
Store-Operated Ca2+ entry (SOCE) is recognized as a key mechanism in muscle physiology necessary to refill intracellular Ca2+ stores during sustained muscle activity. For many years the cell structures expected to mediate SOCE in skeletal muscle fibres remained unknown. Recently, the identification of Ca2+ Entry Units (CEUs) in exercised muscle fibres opened new insights into the role of extracellular Ca2+ in muscle contraction and, more generally, in intracellular Ca2+ homeostasis. Accordingly, intracellular Ca2+ unbalance due to alterations in SOCE strictly correlates with muscle disfunction and disease. Mutations in proteins involved in SOCE (STIM1, ORAI1, and CASQ1) have been linked to tubular aggregate myopathy (TAM), a disease that causes muscle weakness and myalgia and is characterized by a typical accumulation of highly ordered and packed membrane tubules originated from the sarcoplasmic reticulum (SR). Achieving a full understanding of the molecular pathways activated by alterations in Ca2+ entry mechanisms is a necessary step to design effective therapies for human SOCE-related disorders.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Barbara Girolami
- CAST, Center for Advanced Studies and Technology; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy; DMSI, Department of Medicine and Aging Sciences; University G. d'Annunzio of Chieti-Pescara, I-66100, Italy
| | - Sara Roccabianca
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy
| | - Daniela Rossi
- DMMS, Department of Molecular and Developmental Medicine; University of Siena, I-53100, Siena Italy.
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5
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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Saxena P, Roccabianca S, Tykocki N. Compound 48/80 increases bladder wall compliance independent of mast cells. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.l7709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pragya Saxena
- Pharmacology and ToxicologyMichigan State UniversityEast LansingMI
| | - Sara Roccabianca
- Pharmacology and ToxicologyMichigan State UniversityEast LanisngMI
| | - Nathan Tykocki
- Pharmacology and ToxicologyMichigan State UniversityEast LansingMI
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7
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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8
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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9
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Tuttle T, Darios E, Watts SW, Roccabianca S. Aortic stiffness is lower when perivascular adipose tissue (PVAT) is included: a novel ex vivo mechanics study. Am J Physiol Heart Circ Physiol 2022; 322:H1003-H1013. [PMID: 35275760 DOI: 10.1152/ajpheart.00574.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Perivascular adipose tissue (PVAT) is increasingly recognized as an essential layer of the functional vasculature, being responsible for producing vasoactive substances and assisting arterial stress relaxation. Here we test the hypothesis that PVAT reduces aortic stiffness. Our model was the thoracic aorta of the male Sprague Dawley rat. Uniaxial mechanical tests for three groups of tissue were performed: aorta +PVAT (+PVAT), aorta - PVAT (-PVAT), and isolated PVAT (PVAT only). The output of the mechanical test is reported in the form of a Cauchy stress-stretch curve. This work presents a novel, physiologically relevant approach to measure mechanical stiffness ex vivo in isolated PVAT. Low-stress stiffness (), high-stress stiffness (), and the stress corresponding to a stretch of 1.2 () were measured as metrics of distensibility. The low-stress stiffness was largest in the -PVAT samples and smallest in PVAT only samples. Both the high-stress stiffness and the stress at 1.2 stretch were significantly higher in -PVAT samples when compared to +PVAT samples. Taken together these results suggest that -PVAT samples are stiffer (less distensible) both at low stress (not significant) as well as at high stress (significant) when compared to +PVAT samples. These conclusions are supported by the results of the continuum mechanics material model we also used to interpret the same experimental data. Thus, tissue stiffness is significantly lower when considering PVAT as part of the aortic wall. As such, PVAT should be considered as a target for improving vascular function in diseases with elevated aortic stiffness, including hypertension.
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Affiliation(s)
- Tyler Tuttle
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, United States
| | - Emma Darios
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, United States
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10
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Hopper SE, Cuomo F, Ferruzzi J, Burris NS, Roccabianca S, Humphrey JD, Figueroa CA. Comparative Study of Human and Murine Aortic Biomechanics and Hemodynamics in Vascular Aging. Front Physiol 2021; 12:746796. [PMID: 34759837 PMCID: PMC8573132 DOI: 10.3389/fphys.2021.746796] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/05/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction: Aging has many effects on the cardiovascular system, including changes in structure (aortic composition, and thus stiffening) and function (increased proximal blood pressure, and thus cardiac afterload). Mouse models are often used to gain insight into vascular aging and mechanisms of disease as they allow invasive assessments that are impractical in humans. Translation of results from murine models to humans can be limited, however, due to species-specific anatomical, biomechanical, and hemodynamic differences. In this study, we built fluid-solid-interaction (FSI) models of the aorta, informed by biomechanical and imaging data, to compare wall mechanics and hemodynamics in humans and mice at two equivalent ages: young and older adults. Methods: For the humans, 3-D computational models were created using wall property data from the literature as well as patient-specific magnetic resonance imaging (MRI) and non-invasive hemodynamic data; for the mice, comparable models were created using population-based properties and hemodynamics as well as subject-specific anatomies. Global aortic hemodynamics and wall stiffness were compared between humans and mice across age groups. Results: For young adult subjects, we found differences between species in pulse pressure amplification, compliance and resistance distribution, and aortic stiffness gradient. We also found differences in response to aging between species. Generally, the human spatial gradients of stiffness and pulse pressure across the aorta diminished with age, while they increased for the mice. Conclusion: These results highlight key differences in vascular aging between human and mice, and it is important to acknowledge these when using mouse models for cardiovascular research.
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Affiliation(s)
- Sara E. Hopper
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Federica Cuomo
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Jacopo Ferruzzi
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Nicholas S. Burris
- Department of Radiology, University of Michigan, Ann Arbor, MI, United States
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, United States
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
- Vascular Biology and Therapeutics Program, Yale University, New Haven, CT, United States
| | - C. Alberto Figueroa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Surgery, University of Michigan, Ann Arbor, MI, United States
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11
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Roccabianca S, Tuttle T, Flood E, Watts SW. Abstract MP18: The Impact Of Perivascular Adipose Tissue On Arterial Stiffness. Hypertension 2021. [DOI: 10.1161/hyp.78.suppl_1.mp18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PVAT is increasingly recognized as an essential layer of the functional vasculature, producing vasoactive substances and assisting arterial stress relaxation. We test the hypothesis that PVAT reduces arterial stiffness. Our model was the thoracic aorta of the male Sprague Dawley rat. Uniaxial mechanical tests for three tissue groups were performed: aorta +PVAT (+PVAT), aorta - PVAT (-PVAT), and PVAT ring separated from aorta (PVAT only) (N=5). Data are reported in the form of a Cauchy stress-stretch curve (fig 1a; line = mean;shaded = SDs). Low-stress stiffness (
E
o
), high-stress stiffness (
E
1
), and the stress corresponding to a stretch of 1.2 (sigma 1.2) were also measured (+PVAT sample in fig 1b) as metrics of distensibility (the higher the stress/stiffness, the less distensible).
E
1
and sigma
1.2
for PVAT-only samples could not be quantified. The low-stress stiffness
E
o
was the largest in the -PVAT samples and the smallest in PVAT-only samples (p < 0.05), while the +PVAT samples assumed values in the middle. Both the high-stress stiffness
E
1
and the stress at 1.2 stretch (sigma
1.2
) were significantly higher in -PVAT samples when compared to +PVAT samples (p < 0.05). Taken together these results suggest that -PVAT samples are stiffer both at low stress (not significant) as well as at high stress (significant) when compared to +PVAT samples. Moreover, -PVAT samples appear to also be less distensible (higher values of sigma
1.2
) when compared to +PVAT samples. Thus, PVAT contributes significantly to decreasing the stiffness of the aortic wall. As such, PVAT should be considered as a target for improving vascular function in diseases with elevated aortic stiffness, including hypertension.
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Affiliation(s)
| | | | - Emma Flood
- MICHIGAN STATE UNIVERSITY, East Lansing, MI
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12
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Tuttle TG, Morhardt DR, Poli AA, Park JM, Arruda EM, Roccabianca S. Investigation of Fiber-Driven Mechanical Behavior of Human and Porcine Bladder Tissue Tested Under Identical Conditions. J Biomech Eng 2021; 143:1111616. [PMID: 34159357 DOI: 10.1115/1.4051525] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Indexed: 11/08/2022]
Abstract
The urinary bladder is a highly dynamic organ that undergoes large deformations several times per day. Mechanical characteristics of the tissue are crucial in determining the function and dysfunction of the organ. Yet, literature reporting on the mechanical properties of human bladder tissue is scarce and, at times, contradictory. In this study, we focused on mechanically testing tissue from both human and pig bladders using identical protocols to validate the use of pigs as a model for the human bladder. Furthermore, we tested the effect of two treatments on tissue mechanical properties. Namely, elastase to digest elastin fibers, and oxybutynin to reduce smooth muscle cell spasticity. Additionally, mechanical properties based on the anatomical direction of testing were evaluated. We implemented two different material models to aid in the interpretation of the experimental results. We found that human tissue behaves similarly to pig tissue at high deformations (collagen-dominated behavior) while we detected differences between the species at low deformations (amorphous matrix-dominated behavior). Our results also suggest that elastin could play a role in determining the behavior of the fiber network. Finally, we confirmed the anisotropy of the tissue, which reached higher stresses in the transverse direction when compared to the longitudinal direction.
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Affiliation(s)
- Tyler G Tuttle
- Mechanical Engineering Department, Michigan State University, 474 S. Shaw Lane, East Lansing, MI 48824
| | - Duncan R Morhardt
- Department of Urology, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115
| | - Andrea A Poli
- Mechanical Engineering Department, University of Michigan, 2350 Hayward Street, Ann Arbor, MI 48109
| | - John M Park
- Department of Urology, Michigan Medicine, 1500 E. Medical Drive, Ann Arbor, MI 48019
| | - Ellen M Arruda
- Mechanical Engineering Department, University of Michigan, 2350 Hayward Street, Ann Arbor, MI 48109
| | - Sara Roccabianca
- Mechanical Engineering Department, Michigan State University, 474 S. Shaw Lane, East Lansing, MI 48824
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13
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Saxena P, Roccabianca S, Tykocki N. The mast cell activator Compound 48/80 increases bladder compliance through matrix metalloprotease release. FASEB J 2021. [DOI: 10.1096/fasebj.2021.35.s1.00448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pragya Saxena
- Pharmacology and ToxicologyMichigan State UniversityEast LansingMI
| | | | - Nathan Tykocki
- Pharmacology and ToxicologyMichigan State UniversityEast LansingMI
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14
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Wang Y, Gharahi H, Grobbel MR, Rao A, Roccabianca S, Baek S. Potential damage in pulmonary arterial hypertension: An experimental study of pressure-induced damage of pulmonary artery. J Biomed Mater Res A 2021; 109:579-589. [PMID: 32589778 DOI: 10.1002/jbm.a.37042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 05/11/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022]
Abstract
Pulmonary arterial hypertension (PAH) is associated with elevated pulmonary arterial pressure. PAH prognosis remains poor with a 15% mortality rate within 1 year, even with modern clinical management. Previous clinical studies proposed wall shear stress (WSS) to be an important hemodynamic factor affecting cell mechanotransduction, growth and remodeling, and disease progress in PAH. However, WSS in vivo is typically at most 2.5 Pa and a doubt has been cast whether WSS alone can drive disease progress. Furthermore, our current understanding of PAH pathology largely comes from small animals' studies in which caliber enlargement, a hallmark of PAH in humans, is rarely reported. Therefore, a large-animal experiment on pulmonary arteries (PAs) is needed to validate whether increased pressure can induce enlargement of PAs caliber. In this study, we use an inflation testing device to characterize the mechanical behavior, both nonlinear elastic behavior and irreversible damage of porcine arteries. The parameters of elastic behavior are estimated from the inflation test at a low-pressure range before and after over-pressurization. Then, histological images are qualitatively examined for medial and adventitial layers. This study sheds light on the relevance of pressure-induced damage mechanism in human PAH.
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Affiliation(s)
- Yuheng Wang
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Hamidreza Gharahi
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Marissa R Grobbel
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Akshay Rao
- Department of Mechanical Engineering, Texas A&M University, College Station, Texas, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
| | - Seungik Baek
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, USA
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15
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Grobbel MR, Lee LC, Watts SW, Fink GD, Roccabianca S. Left ventricular geometry, tissue composition, and residual stress in High Fat Diet Dahl-Salt sensitive rats. Exp Mech 2021; 61:191-201. [PMID: 33776071 PMCID: PMC7990029 DOI: 10.1007/s11340-020-00664-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 09/02/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Hypertension drives myocardial remodeling, leading to changes in structure, composition and mechanical behavior, including residual stress, which are linked to heart disease progression in a gender-specific manner. Emerging therapies are also targeting constituent-specific pathological features. All previous studies, however, have characterized remodeling in the intact tissue, rather than isolated tissue constituents, and did not include sex as a biological variable. OBJECTIVE In this study we first identified the contribution of collagen fiber network and myocytes to the myocardial residual stress/strain in Dahl-Salt sensitive rats fed with high fat diet. Then, we quantified the effect of hypertension on the remodeling of the left ventricle (LV), as well as the existence of sex-specific remodeling features. METHODS We performed mechanical tests (opening angle, ring-test) and histological analysis on isolated constituents and intact tissue of the LV. Based on the measurements from the tests, we performed a stress analysis to evaluate the residual stress distribution. Statistical analysis was performed to identify the effects of constituent isolation, elevated blood pressure, and sex of the animal on the output of both experimental measures and modeling results. RESULTS Hypertension leads to reduced residual stress/strain intact tissue, isolated collagen fibers, and isolated myocytes in male and female rats. Collagen remains the largest contributor to myocardial residual stress in both normotensive and hypertensive animals. We identified sex-differences in both hypertensive and normotensive animals. CONCLUSIONS We observed both constituent- and sex-specific remodeling features in the LV of an animal model of hypertension.
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Affiliation(s)
- M. R. Grobbel
- Michigan State University, Mechanical Engineering Department
| | - L. C. Lee
- Michigan State University, Mechanical Engineering Department
| | - S. W. Watts
- Michigan State University, Pharmacology & Toxicology Department
| | - G. D. Fink
- Michigan State University, Pharmacology & Toxicology Department
| | - S. Roccabianca
- Michigan State University, Mechanical Engineering Department
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16
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Izadi A, Sinha M, Papson C, Roccabianca S, Anthony R. Mechanical behavior of SiNC layers on PDMS: effects of layer thickness, PDMS modulus, and SiNC surface functionality. RSC Adv 2020; 10:39087-39091. [PMID: 35518434 PMCID: PMC9057323 DOI: 10.1039/d0ra06321e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/22/2020] [Indexed: 11/30/2022] Open
Abstract
Thin layers of nanomaterials on stretchable substrates have the potential to enable stretchable, bendable optoelectronic devices, wearable diagnostics, and more. Recently, our group reported on a novel method for finding the neo-Hookean coefficient of thin layers of silicon nanocrystals (SiNCs) on polydimethylsiloxane (PDMS). Here we elaborate on that initial study by examining the effects of the SiNC layer thickness, PDMS neo-Hookean coefficient, and SiNC surface functionality on the neo-Hookean coefficient of the SiNC layers. We found that, while the layer thickness and PDMS neo-Hookean coefficient influence the behavior of the SiNC layers, layers of surface-functionalized SiNCs do not exhibit disparate behavior from layers of bare SiNCs. Experimental/theoretical estimations of the neo-Hookean coefficients of SiNC layers on PDMS show a dependence on layer thickness as well as on the modulus of the PDMS, but not on the surface functionality of the SiNCs.![]()
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Affiliation(s)
- Alborz Izadi
- Department of Mechanical Engineering, Michigan State University East Lansing MI USA +1-517-353-1750 +1-517-432-7491
| | - Mayank Sinha
- Department of Mechanical Engineering, Michigan State University East Lansing MI USA +1-517-353-1750 +1-517-432-7491
| | - Cameron Papson
- Department of Mechanical Engineering, Michigan State University East Lansing MI USA +1-517-353-1750 +1-517-432-7491
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University East Lansing MI USA +1-517-353-1750 +1-517-432-7491
| | - Rebecca Anthony
- Department of Mechanical Engineering, Michigan State University East Lansing MI USA +1-517-353-1750 +1-517-432-7491
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17
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Scott J, Chen S, Roccabianca S, Bush TR. The effects of body position on the material properties of soft tissue in the human thigh. J Mech Behav Biomed Mater 2020; 110:103964. [DOI: 10.1016/j.jmbbm.2020.103964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 06/10/2020] [Accepted: 06/29/2020] [Indexed: 02/07/2023]
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18
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Upchurch DA, Wang Y, Chen S, Roccabianca S, Roush JK. Assessment of time to completion, number of errors, and knot-holding capacity of square knots and Aberdeen knots tied by veterinary students and student perceptions of knot security and knot-tying difficulty. J Am Vet Med Assoc 2020; 256:230-238. [PMID: 31910084 DOI: 10.2460/javma.256.2.230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the time to completion, number of errors, and knot-holding capacity (KHC) for starting and ending square knots (SSKs and ESKs) of a continuous pattern and Aberdeen knots tied by veterinary students and to investigate student perceptions of knot security and knot-tying difficulty for the 3 knot types. SAMPLE 16 second-year veterinary students. PROCEDURES Students created 3 (4-throw) SSKs, 3 (5-throw) ESKs, and 3 (3 + 1 configuration) Aberdeen knots with 2-0 polydioxanone on a custom test apparatus. Time to complete each knot, the number of errors in each knot, and student ratings of knot-tying difficulty and confidence in knot security were recorded. Each knot was tested to failure on a uniaxial tensiometer to determine KHC and mode of failure. Variables of interest were compared by repeated-measures ANOVA or the Friedman test with post hoc pairwise comparisons. RESULTS Mean knot completion time for Aberdeen knots was significantly less than mean completion time for SSKs or ESKs. Mean KHC was significantly lower for ESKs than for SSKs; KHC for Aberdeen knots was not compared with these values because of methodological differences. Median error rate was higher for ESKs than for other knot types. Mean difficulty rating for Aberdeen knots was lower than that for ESKs. Most tested knots failed by breakage at the knot. CONCLUSIONS AND CLINICAL RELEVANCE Aberdeen knots appeared to be easy for veterinary students to learn and were completed more rapidly and with fewer errors than ESKs. Including this type of knot in surgical skills curriculum for novices may be beneficial.
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19
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Saxena P, Tykocki N, Roccabianca S. Smooth Muscle Tone Contributes to Bladder Wall Stiffness during Filling. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.02613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Roccabianca S, Flood E, Garver H, Fink G, Watts SW. Abstract P2023: Perivascular Adipose Tissue Assists Arterial Stress Relaxation: Loss of Assistance in Obesity-Associated Hypertension. Hypertension 2019. [DOI: 10.1161/hyp.74.suppl_1.p2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In health, PVAT contributes anti-contractile factors, such as adiponectin, that relax the artery. This benefit is lost in cardiovascular disease, including hypertension. We discovered that PVAT’s contributions to arterial function include more than production of vasoactive substances. Using isometric techniques, we tested the hypothesis that PVAT provided structural benefit to the arterial wall by assisting the function of stress relaxation (SR). Arterial rings were mounted with (+) and without (-) PVAT, from the same animal, and taken through a cumulative length tension curve, in which increasing tension (0 - 6 grams) was added. Tissues relaxed for 30 minutes prior to measuring the tension to which the tissue relaxed. Tissues were then challenged with phenylephrine (10
-5
M) for viability at each tension. In thoracic aorta isolated from normal male Sprague-Dawley rats, the presence of PVAT (a brown fat) along the vessel wall assisted SR by reducing the maximum (6 g) cumulative tension achieved (in mgs; -PVAT = 4578±190; +PVAT = 2730±274, p<0.05). Similarly, the PVAT in the superior mesenteric artery (a white fat) promoted SR in a cumulative length tension curve, resulting in a final tension reduced 19% compared to rings -PVAT. The physical association of PVAT with the vessel wall was essential; when PVAT was left only attached to the
ends
of the aortic rings, it provided no benefit in cumulative SR (+/-PVAT = 4122±176). Thus, passive secretion of anticontractile factors does not contribute to stress relaxation. Rather, PVAT must itself be stretched to result in production of humoral factors and/or it alone provides a mechanical benefit. Importantly, PVAT-assisted SR was lost in the thoracic aorta of the hypertensive DahlS rat (systolic BP = 175±9 mm Hg at 17 weeks) fed a high fat diet for 21 weeks (HF -PVAT = 4218±95; +PVAT = 4135±232; p>0.05) when compared to their controls (Con - PVAT = 4422±85; +PVAT = 3706±165; p<0.05; SBP = 111 ± 7 mm Hg). These important findings change how a blood vessel must be considered. PVAT is an essential functional element that should be considered in health and disease.
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21
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Pan W, Roccabianca S, Basson MD, Bush TR. Influences of sodium and glycosaminoglycans on skin oedema and the potential for ulceration: a finite-element approach. R Soc Open Sci 2019; 6:182076. [PMID: 31417698 PMCID: PMC6689624 DOI: 10.1098/rsos.182076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/03/2019] [Indexed: 06/10/2023]
Abstract
Venous ulcers are chronic transcutaneous wounds common in the lower legs. They are resistant to healing and have a 78% chance of recurrence within 2 years. It is commonly accepted that venous ulcers are caused by the insufficiency of the calf muscle pump, leading to blood pooling in the lower legs, resulting in inflammation, skin oedema, tissue necrosis and eventually skin ulceration. However, the detailed physiological events by which inflammation contributes to wound formation are poorly understood. We therefore sought to develop a model that simulated the inflammation, using it to determine the internal stresses and pressure on the skin that contribute to venous ulcer formation. A three-layer finite-element skin model (epidermis, dermis and hypodermis) was developed to explore the roles in wound formation of two inflammation identifiers: glycosaminoglycans (GAG) and sodium. A series of parametric studies showed that increased GAG and sodium content led to oedema and increased tissue stresses of 1.5 MPa, which was within the reported range of skin tissue ultimate tensile stress (0.1-40 MPa). These results suggested that both the oedema and increased fluid pressure could reach a threshold for tissue damage and eventual ulcer formation. The models presented here provide insights to the pathological events associated with venous insufficiency, including inflammation, oedema and skin ulceration.
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Affiliation(s)
- Wu Pan
- Department of Mechanical Engineering, Michigan State University, 428 South Shaw Lane, Room 2555, East Lansing, MI 48824, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, 428 South Shaw Lane, Room 2555, East Lansing, MI 48824, USA
| | - Marc D. Basson
- Department of Surgery at the University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Tamara Reid Bush
- Department of Mechanical Engineering, Michigan State University, 428 South Shaw Lane, Room 2555, East Lansing, MI 48824, USA
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22
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Sinha M, Izadi A, Anthony R, Roccabianca S. A novel approach to finding mechanical properties of nanocrystal layers. Nanoscale 2019; 11:7520-7526. [PMID: 30942804 DOI: 10.1039/c9nr02213a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Flexible, bendable, stretchable devices represent the future of electronics for a wide range of real-world applications. Due to the fact that these technologies deviate significantly from traditional wafer technologies there is a need to understand and engineer material systems that allow large elastic deformations present in such devices, which requires knowledge about the mechanical properties of these material systems. Here we evaluate the mechanical properties of a bilayer polydimethylsiloxane (PDMS)/silicon nanocrystal system. By observing the formation of instabilities due to finite bending deformation and applying theoretical modeling, we estimated the neo-Hookean coefficient (analogous to shear modulus at low stress/strain) of the silicon nanocrystal film to be 345 ± 23 kPa. The method used here represents a novel approach to evaluating these properties and is widely applicable to many different combinations of systems of nanocrystals and elastomers.
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Affiliation(s)
- Mayank Sinha
- Michigan State University, East Lansing, MI, USA.
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23
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Bula E, Upchurch DA, Wang Y, Chen S, Roccabianca S. Comparison of tensile strength and time to closure between an intermittent Aberdeen suture pattern and conventional methods of closure for the body wall of dogs. Am J Vet Res 2018; 79:115-123. [PMID: 29287163 DOI: 10.2460/ajvr.79.1.115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare tensile strength and time to completion of body wall closure among 3 suture patterns. SAMPLE Eighteen 5 × 5-cm leather specimens and sixty-eight 5 × 5-cm full-thickness tissue specimens from the ventral portion of the abdominal body wall of 17 canine cadavers. PROCEDURES During experiment 1 of a 2-experiment study, each leather specimen was cut in half and sutured with a simple interrupted or simple continuous pattern or continuous pattern with intermittent Aberdeen knots (intermittent Aberdeen pattern). During experiment 2, 4 tissue specimens were obtained from each cadaver; the linea alba of 3 specimens was incised and closed with 1 of the 3 suture patterns evaluated in experiment 1, and the fourth specimen was left intact as a control. All leather and tissue specimens underwent mechanical testing. Time to completion, mode of failure, and maximum force at failure (Fmax) were compared among the suture patterns. RESULTS In experiment 1, the mean Fmax for the simple continuous and intermittent Aberdeen patterns was significantly greater than that for the simple interrupted pattern. In experiment 2, the mean Fmax for specimens obtained cranial to the umbilicus was greater than that for specimens obtained caudal to the umbilicus, and the mean time to completion for both continuous suture patterns was significantly less than that for the simple interrupted pattern. Most (34/51) sutured tissue specimens failed because the suture cut through the tissue at the suture-tissue interface. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the intermittent Aberdeen pattern may be an alternative for body wall closure in dogs.
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24
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Grobbel MR, Shavik SM, Darios E, Watts SW, Lee LC, Roccabianca S. Contribution of left ventricular residual stress by myocytes and collagen: existence of inter-constituent mechanical interaction. Biomech Model Mechanobiol 2018; 17:985-999. [PMID: 29478195 DOI: 10.1007/s10237-018-1007-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 02/10/2018] [Indexed: 11/29/2022]
Abstract
We quantify the contribution of myocytes, collagen fibers and their interactions to the residual stress field found in the left ventricle (LV) using both experimental and theoretical methods. Ring tissue samples extracted from normal rat, male and female, LV were treated with collagenase and decellularization to isolate myocytes and collagen fibers, respectively. Opening angle tests were then performed on these samples as well as intact tissue samples containing both constituents that served as control. Our results show that the collagen fibers are the main contributor to the residual stress fields found in the LV. Specifically, opening angle measured in collagen-only samples (106.45[Formula: see text] ± 23.02[Formula: see text]) and myocytes-only samples (21.00[Formula: see text] ± 4.37[Formula: see text]) was significantly higher and lower than that of the control (57.88[Formula: see text] ± 12.29[Formula: see text]), respectively. A constrained mixture (CM) modeling framework was then used to infer these experimental results. We show that the framework cannot reproduce the opening angle found in the intact tissue with measurements made on the collagen-only and myocytes-only samples. Given that the CM framework assumes that each constituent contributes to the overall mechanics simply by their mere presence, this result suggests the existence of some myocyte-collagen mechanical interaction that cannot be ignored in the LV. We then propose an extended CM formulation that takes into account of the inter-constituent mechanical interaction in which constituents are deformed additionally when they are physically combined into a mixture. We show that the intact tissue opening angle can be recovered in this framework.
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Affiliation(s)
- Marissa R Grobbel
- Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48824, USA
| | | | - Emma Darios
- Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48824, USA
| | - Stephanie W Watts
- Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48824, USA
| | - Lik Chuan Lee
- Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48824, USA
| | - Sara Roccabianca
- Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48824, USA.
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25
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Pan W, Drost JP, Roccabianca S, Baek S, Bush TR. A Potential Tool for the Study of Venous Ulcers: Blood Flow Responses to Load. J Biomech Eng 2018; 140:2666615. [DOI: 10.1115/1.4038742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Indexed: 11/08/2022]
Abstract
Venous ulcers are deep wounds that are located predominantly on the lower leg. They are prone to infection and once healed have a high probability of recurrence. Currently, there are no effective measures to predict and prevent venous ulcers from formation. Hence, the goal of this work was to develop a Windkessel-based model that can be used to identify hemodynamic parameters that change between healthy individuals and those with wounds. Once identified, these parameters have the potential to be used as indicators of when internal conditions change, putting the patient at higher risk for wound formation. In order to achieve this goal, blood flow responses in lower legs were measured experimentally by a laser Doppler perfusion monitor (LDPM) and simulated with a modeling approach. A circuit model was developed on the basis of the Windkessel theory. The hemodynamic parameters were extracted for three groups: legs with ulcers (“wounded”), legs without ulcers but from ulcer patients (“nonwounded”), and legs without vascular disease (“healthy”). The model was executed by two independent operators, and both operators reported significant differences between wounded and healthy legs in localized vascular resistance and compliance. The model successfully replicated the experimental blood flow profile. The global and local vascular resistances and compliance parameters rendered quantifiable differences between a population with venous ulcers and healthy individuals. This work supports that the Windkessel modeling approach has the potential to determine patient specific parameters that can be used to identify when conditions change making venous ulcer formation more likely.
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Affiliation(s)
- Wu Pan
- Fellow ASME Department of Mechanical Engineering, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226 e-mail:
| | - Joshua P. Drost
- Fellow ASME Department of Mechanical Engineering, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226 e-mail:
| | - Sara Roccabianca
- Fellow ASME Department of Mechanical Engineering, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226 e-mail:
| | - Seungik Baek
- Fellow ASME Department of Mechanical Engineering, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226 e-mail:
| | - Tamara Reid Bush
- Fellow ASME Chair of the Dynamics, Design and Rehabilitation (DDR) Committee, Bioengineering Technical Division, Department of Mechanical Engineering, Michigan State University, 2555 Engineering Building, East Lansing, MI 48824-1226 e-mail:
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26
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Cuomo F, Roccabianca S, Dillon-Murphy D, Xiao N, Humphrey JD, Figueroa CA. Effects of age-associated regional changes in aortic stiffness on human hemodynamics revealed by computational modeling. PLoS One 2017; 12:e0173177. [PMID: 28253335 PMCID: PMC5333881 DOI: 10.1371/journal.pone.0173177] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 02/16/2017] [Indexed: 02/04/2023] Open
Abstract
Although considered by many as the gold standard clinical measure of arterial stiffness, carotid-to-femoral pulse wave velocity (cf-PWV) averages material and geometric properties over a large portion of the central arterial tree. Given that such properties may evolve differentially as a function of region in cases of hypertension and aging, among other conditions, there is a need to evaluate the potential utility of cf-PWV as an early diagnostic of progressive vascular stiffening. In this paper, we introduce a data-driven fluid-solid-interaction computational model of the human aorta to simulate effects of aging-related changes in regional wall properties (e.g., biaxial material stiffness and wall thickness) and conduit geometry (e.g., vessel caliber, length, and tortuosity) on several metrics of arterial stiffness, including distensibility, augmented pulse pressure, and cyclic changes in stored elastic energy. Using the best available biomechanical data, our results for PWV compare well to findings reported for large population studies while rendering a higher resolution description of evolving local and global metrics of aortic stiffening. Our results reveal similar spatio-temporal trends between stiffness and its surrogate metrics, except PWV, thus indicating a complex dependency of the latter on geometry. Lastly, our analysis highlights the importance of the tethering exerted by external tissues, which was iteratively estimated until hemodynamic simulations recovered typical values of tissue properties, pulse pressure, and PWV for each age group.
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Affiliation(s)
- Federica Cuomo
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, Michigan, United States of America
| | | | - Nan Xiao
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States of America
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, Connecticut, United States of America
| | - C. Alberto Figueroa
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Biomedical Engineering, King’s College London, London, United Kingdom
- Department of Surgery, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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27
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Sorrentino TA, Fourman L, Ferruzzi J, Miller KS, Humphrey JD, Roccabianca S. Local versus global mechanical effects of intramural swelling in carotid arteries. J Biomech Eng 2015; 137:041008. [PMID: 25474096 DOI: 10.1115/1.4029303] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Indexed: 01/09/2023]
Abstract
Glycosaminoglycans (GAGs) are increasingly thought to play important roles in arterial mechanics and mechanobiology. We recently suggested that these highly negatively charged molecules, well known for their important contributions to cartilage mechanics, can pressurize intralamellar units in elastic arteries via a localized swelling process and thereby impact both smooth muscle mechanosensing and structural integrity. In this paper, we report osmotic loading experiments on murine common carotid arteries that revealed different degrees and extents of transmural swelling. Overall geometry changed significantly with exposure to hypo-osmotic solutions, as expected, yet mean pressure-outer diameter behaviors remained largely the same. Histological analyses revealed further that the swelling was not always distributed uniformly despite being confined primarily to the media. This unexpected finding guided a theoretical study of effects of different distributions of swelling on the wall stress. Results suggested that intramural swelling can introduce highly localized changes in the wall mechanics that could induce differential mechanobiological responses across the wall. There is, therefore, a need to focus on local, not global, mechanics when examining issues such as swelling-induced mechanosensing.
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Roccabianca S, Bellini C, Humphrey JD. Computational modelling suggests good, bad and ugly roles of glycosaminoglycans in arterial wall mechanics and mechanobiology. J R Soc Interface 2015; 11:20140397. [PMID: 24920112 DOI: 10.1098/rsif.2014.0397] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The medial layer of large arteries contains aggregates of the glycosaminoglycan hyaluronan and the proteoglycan versican. It is increasingly thought that these aggregates play important mechanical and mechanobiological roles despite constituting only a small fraction of the normal arterial wall. In this paper, we offer a new hypothesis that normal aggregates of hyaluronan and versican pressurize the intralamellar spaces, and thereby put into tension the radial elastic fibres that connect the smooth muscle cells to the elastic laminae, which would facilitate mechanosensing. This hypothesis is supported by novel computational simulations using two complementary models, a mechanistically based finite-element mixture model and a phenomenologically motivated continuum hyperelastic model. That is, the simulations suggest that normal aggregates of glycosaminoglycans/proteoglycans within the arterial media may play equally important roles in supporting (i.e. a structural role) and sensing (i.e. an instructional role) mechanical loads. Additional simulations suggest further, however, that abnormal increases in these aggregates, either distributed or localized, may over-pressurize the intralamellar units. We submit that these situations could lead to compromised mechanosensing, anoikis and/or reduced structural integrity, each of which represent fundamental aspects of arterial pathologies seen, for example, in hypertension, ageing and thoracic aortic aneurysms and dissections.
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Affiliation(s)
- S Roccabianca
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - C Bellini
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - J D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
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Roccabianca S, Figueroa C, Tellides G, Humphrey J. Quantification of regional differences in aortic stiffness in the aging human. J Mech Behav Biomed Mater 2014; 29:618-34. [PMID: 23499251 PMCID: PMC3842391 DOI: 10.1016/j.jmbbm.2013.01.026] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 01/28/2013] [Accepted: 01/30/2013] [Indexed: 01/29/2023]
Abstract
There has been a growing awareness over the past decade that stiffening of the aorta, and its attendant effects on hemodynamics, is both an indicator and initiator of diverse cardiovascular, neurovascular, and renovascular diseases. Although different clinical metrics of arterial stiffness have been proposed and found useful in particular situations, there remains a need to understand better the complex interactions between evolving aortic stiffness and the hemodynamics. Computational fluid-solid-interaction (FSI) models are amongst the most promising means to understand such interactions for one can parametrically examine effects of regional variations in material properties and arterial geometry on local and systemic blood pressure and flow. Such models will not only increase our understanding, they will also serve as important steps towards the development of fluid-solid-growth (FSG) models that can further examine interactions between the evolving wall mechanics and hemodynamics that lead to arterial adaptations or disease progression over long periods. In this paper, we present a consistent quantification and comparison of regional nonlinear biaxial mechanical properties of the human aorta based on 19 data sets available in the literature and we calculate associated values of linearized stiffness over the cardiac cycle that are useful for initial large-scale FSI and FSG simulations. It is shown, however, that there is considerable variability amongst the available data and consequently that there is a pressing need for more standardized biaxial testing of the human aorta to collect data as a function of both location and age, particularly for young healthy individuals who serve as essential controls.
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Affiliation(s)
- S. Roccabianca
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520-8260, USA
| | - C.A. Figueroa
- Department of Bioengineering, King’s College London, England, SE1 8WA, UK
| | - G. Tellides
- Department of Surgery, Yale School of Medicine, New Haven, CT 06510, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT 06510, USA
| | - J.D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520-8260, USA
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT 06510, USA
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Bellini C, Ferruzzi J, Roccabianca S, Di Martino ES, Humphrey JD. A microstructurally motivated model of arterial wall mechanics with mechanobiological implications. Ann Biomed Eng 2013; 42:488-502. [PMID: 24197802 DOI: 10.1007/s10439-013-0928-x] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/10/2013] [Indexed: 01/26/2023]
Abstract
Through mechanobiological control of the extracellular matrix, and hence local stiffness, smooth muscle cells of the media and fibroblasts of the adventitia play important roles in arterial homeostasis, including adaptations to altered hemodynamics, injury, and disease. We present a new approach to model arterial wall mechanics that seeks to define better the mechanical environments of the media and adventitia while avoiding the common prescription of a traction-free reference configuration. Specifically, we employ the concept of constituent-specific deposition stretches from the growth and remodeling literature and define a homeostatic state at physiologic pressure and axial stretch that serves as a convenient biologically and clinically relevant reference configuration. Information from histology and multiphoton imaging is then used to prescribe structurally motivated constitutive relations for a bi-layered model of the wall. The utility of this approach is demonstrated by describing in vitro measured biaxial pressure-diameter and axial force-length responses of murine carotid arteries and predicting the associated intact and radially cut traction-free configurations. The latter provides a unique validation while confirming that this constrained mixture approach naturally recovers estimates of residual stresses, which are fundamental to wall mechanics, without the usual need to prescribe an opening angle that is only defined conveniently on cylindrical geometries and cannot be measured in vivo. Among other findings, the model suggests that medial and adventitial stresses can be nearly uniform at physiologic loads, albeit at separate levels, and that the adventitia bears increasingly more load at supra-physiologic pressures while protecting the media from excessive stresses.
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Affiliation(s)
- C Bellini
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, New Haven, CT, 06511, USA
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Roccabianca S, Ateshian GA, Humphrey JD. Biomechanical roles of medial pooling of glycosaminoglycans in thoracic aortic dissection. Biomech Model Mechanobiol 2013; 13:13-25. [PMID: 23494585 DOI: 10.1007/s10237-013-0482-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 03/01/2013] [Indexed: 01/22/2023]
Abstract
Spontaneous dissection of the human thoracic aorta is responsible for significant morbidity and mortality, yet this devastating biomechanical failure process remains poorly understood. In this paper, we present finite element simulations that support a new hypothesis for the initiation of aortic dissections that is motivated by extensive histopathological observations. Specifically, our parametric simulations show that the pooling of glycosaminoglycans/proteoglycans that is singularly characteristic of the compromised thoracic aorta in aneurysms and dissections can lead to significant stress concentrations and intra-lamellar Donnan swelling pressures. We submit that these localized increases in intramural stress may be sufficient both to disrupt the normal cell-matrix interactions that are fundamental to aortic homeostasis and to delaminate the layered microstructure of the aortic wall and thereby initiate dissection. Hence, pathologic pooling of glycosaminoglycans/proteoglycans within the medial layer of the thoracic aortic should be considered as a possible target for clinical intervention.
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Affiliation(s)
- Sara Roccabianca
- Department of Biomedical Engineering, Malone Engineering Center, Yale University, 55 Prospect Street, New Haven, CT, 06520, USA
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