+publisher:"Georgia Tech" +contributor:("Ajit P. Yoganathan")

Georgia Tech

1. Jimenez-Mejia, Jorge Hernan. The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study.

Degree: MS, Biomedical Engineering, 2003, Georgia Tech

URL: http://hdl.handle.net/1853/36545

Subjects/Keywords: Mitral valve; Transducers, Biomedical

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APA (6^th Edition):

Jimenez-Mejia, J. H. (2003). The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/36545

Chicago Manual of Style (16^th Edition):

Jimenez-Mejia, Jorge Hernan. “The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study.” 2003. Masters Thesis, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/36545.

MLA Handbook (7^th Edition):

Jimenez-Mejia, Jorge Hernan. “The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study.” 2003. Web. 06 Mar 2021.

Vancouver:

Jimenez-Mejia JH. The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study. [Internet] [Masters thesis]. Georgia Tech; 2003. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/36545.

Council of Science Editors:

Jimenez-Mejia JH. The effects of mitral annular dynamics and papillary muscle position of chordal force distribution and valve function : an in vitro study. [Masters Thesis]. Georgia Tech; 2003. Available from: http://hdl.handle.net/1853/36545

Georgia Tech

2. Simpson, Michael S. An in vitro investigation of systolic anterior motion of the mitral valve.

Degree: MS, Mechanical engineering, 1992, Georgia Tech

URL: http://hdl.handle.net/1853/33615

Subjects/Keywords: Aortic valve stenosis; Mitral valve Diseases; Heart valves Diseases

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APA (6^th Edition):

Simpson, M. S. (1992). An in vitro investigation of systolic anterior motion of the mitral valve. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/33615

Chicago Manual of Style (16^th Edition):

Simpson, Michael S. “An in vitro investigation of systolic anterior motion of the mitral valve.” 1992. Masters Thesis, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/33615.

MLA Handbook (7^th Edition):

Simpson, Michael S. “An in vitro investigation of systolic anterior motion of the mitral valve.” 1992. Web. 06 Mar 2021.

Vancouver:

Simpson MS. An in vitro investigation of systolic anterior motion of the mitral valve. [Internet] [Masters thesis]. Georgia Tech; 1992. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/33615.

Council of Science Editors:

Simpson MS. An in vitro investigation of systolic anterior motion of the mitral valve. [Masters Thesis]. Georgia Tech; 1992. Available from: http://hdl.handle.net/1853/33615

3. Balachandran, Kartik. Aortic valve mechanobiology - the effect of cyclic stretch.

Degree: PhD, Biomedical Engineering, 2010, Georgia Tech

URL: http://hdl.handle.net/1853/39486

► Aortic valve disease is among the third most common cardiovascular disease worldwide, and is also a strong predictor for other cardiac related deaths. Altered mechanical… (more)

Subjects/Keywords: Cyclic stretch; Mechanobiology; Aortic valve; Aortic valve; Cell interaction; Extracellular matrix; Biomechanics

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APA (6^th Edition):

Balachandran, K. (2010). Aortic valve mechanobiology - the effect of cyclic stretch. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/39486

Chicago Manual of Style (16^th Edition):

Balachandran, Kartik. “Aortic valve mechanobiology - the effect of cyclic stretch.” 2010. Doctoral Dissertation, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/39486.

MLA Handbook (7^th Edition):

Balachandran, Kartik. “Aortic valve mechanobiology - the effect of cyclic stretch.” 2010. Web. 06 Mar 2021.

Vancouver:

Balachandran K. Aortic valve mechanobiology - the effect of cyclic stretch. [Internet] [Doctoral dissertation]. Georgia Tech; 2010. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/39486.

Council of Science Editors:

Balachandran K. Aortic valve mechanobiology - the effect of cyclic stretch. [Doctoral Dissertation]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/39486

Georgia Tech

4. Fallon, Anna Marie. The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets.

Degree: PhD, Chemical Engineering, 2006, Georgia Tech

URL: http://hdl.handle.net/1853/10451

► Bileaflet mechanical heart valves (BMHVs) are prone to thrombus formation in the hinge region due to high shear stress combined with stagnation regions. This thesis… (more)

▼ Bileaflet mechanical heart valves (BMHVs) are prone to thrombus formation in the hinge region due to high shear stress combined with stagnation regions. This thesis research addresses the hypothesis that models that isolate and mimic BMHV hinge geometries can be used to quantitatively characterize procoagulant potential using a novel in vitro blood flow system. Furthermore, these results can be correlated with digital particle image velocimetry (DPIV) measurements detailing flow fields for the same models. The significant findings were that: 1) recalcification of recirculating citrated blood markedly increases the magnitude of thrombus forming reactions and the sensitivity for their detection; 2) platelet activation, and the presence of adequate platelet numbers are essential for the activation of coagulation under conditions of high shear; and 3) thrombin formation can be inhibited by blocking the platelet receptors that facilitate platelet aggregation. The DPIV studies give some insight into why different channel geometries resulted in varying propensities for coagulation. The channel geometries with abrupt changes in diameter induced significantly higher levels of TAT and also formed jets that were subject to increased entrainment of the stagnant fluid in the chamber. This entrainment enables more mixing of the shear-activated platelets with the surrounding flow, which can propagate the coagulation cascade, thus increasing the chance for thrombus formation. The influence of abrupt changes in diameter was also evident in the BMHV human blood studies. The MP valve, which has a tortuous hinge pathway, induced significantly more TAT formation than the SJM Standard valve with a smoother hinge channel. Thus, BMHV hinge geometry should be as smooth and free of diameter changes as possible to eliminate stagnation regions that enable activated platelets to congregate and propagate the coagulation cascade. Leakage gap width also had a significant effect not only on procoagulant potential but also on platelet activation. Both the low and high leaker prototype valves had significantly higher levels of platelet activation compared to the SJM Standard valve, but only the low leaker valve demonstrated a higher propensity for coagulation. Thus, to minimize both platelet activation and thromboemboli formation, an optimal gap width should be maintained for BMHVs. Advisors/Committee Members: Ajit P. Yoganathan (Committee Chair), Dale E. Edmondson (Committee Member), Peter J. Ludovice (Committee Member), Stephen R. Hanson (Committee Member), Timothy M. Wick (Committee Member).

Subjects/Keywords: Blood; Thrombosis; Mechanical heart valves; Platelets; Shear stress

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APA (6^th Edition):

Fallon, A. M. (2006). The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/10451

Chicago Manual of Style (16^th Edition):

Fallon, Anna Marie. “The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets.” 2006. Doctoral Dissertation, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/10451.

MLA Handbook (7^th Edition):

Fallon, Anna Marie. “The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets.” 2006. Web. 06 Mar 2021.

Vancouver:

Fallon AM. The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets. [Internet] [Doctoral dissertation]. Georgia Tech; 2006. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/10451.

Council of Science Editors:

Fallon AM. The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets. [Doctoral Dissertation]. Georgia Tech; 2006. Available from: http://hdl.handle.net/1853/10451

Georgia Tech

5. Song, Hannah. Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis.

Degree: PhD, Biomedical Engineering, 2007, Georgia Tech

URL: http://hdl.handle.net/1853/28258

► Atherosclerosis is an inflammatory disease, occurring preferentially in arterial regions with disturbed flow. We have shown that disturbed flow induces inflammation in endothelial cells (ECs)… (more)

▼ Atherosclerosis is an inflammatory disease, occurring preferentially in arterial regions with disturbed flow. We have shown that disturbed flow induces inflammation in endothelial cells (ECs) by producing bone morphogenic protein-4 (BMP4). Moreover, chronic BMP4 infusion induces endothelial dysfunction and systemic hypertension in mice. Here, we examined which BMP receptors (BMPR) mediate BMP4 action in ECs. Western blot, immunostaining and RT-PCR studies using human and bovine ECs, mouse aortas and human coronary arteries (HCA) showed that BMPRI (ALK2 and 6) and BMP-RII were expressed in ECs. As a functional test, ECs were treated with a BMPRII siRNA to knockdown expression. BMPRII knockdown blocked a well-known BMP4 response - smad1/5/8 phosphorylation, as expected. Unexpectedly, BMPRII knockdown itself significantly stimulated ICAM-1 and VCAM-1 expression and monocyte adhesion in a BMP4-independent manner. Inflammatory responses caused by BMPRII knockdown were blocked by inhibitors of NADPH oxidase and NFκ B. From these results, we hypothesized that BMP-RII knockdown in ECs would cause inflammation, which is a critical event in atherosclerosis initiation and progression. Genetic mutations of BMPRII have been linked to primary pulmonary hypertension. However, it is not known whether BMP-RII is regulated by atherosclerotic conditions and plays a role in non-pulmonary vessels causing inflammation and atherosclerosis. We examined BMPRII levels in HCA by immunostaining. While non-diseased arteries showed intense staining of BMPRII, the expression decreased as lesions became more advanced. BMPRII was virtually undetectable in the most advanced lesions. These findings suggested a potential link between pro-atherosclerotic conditions and BMP-RII levels. We tested this hypothesis by treating ECs with pro-inflammatory cytokines found in atheromas: TNFα decreased BMPRII by 2-fold. In contrast, statins increased BMPRII by 4-fold. In summary, we demonstrate for the first time that BMPRII can be down- or up-regulated by pro- or anti-atherogenic conditions, respectively, and it is dramatically decreased in HCA with advanced plaques. Moreover, BMPRII knockdown in ECs induces inflammation, a critical atherogenic step. We propose that focal inflammation initiated by disturbed flow, together with circulating pro-atherogenic risk factors, may lead to a vicious cycle of BMPRII down-regulation causing secondary inflammation and atheroma progression. Advisors/Committee Members: Hanjoong Jo (Committee Chair), Ajit P. Yoganathan (Committee Member), Andrew P. Kowalczyk (Committee Member), David G. Harrison (Committee Member), Kathy K. Griendling (Committee Member).

Subjects/Keywords: BMPRII; Inflammation; Endothelial cells; Atherosclerosis; Atherosclerosis; Bone morphogenetic proteins; Endothelium; Inflammation; Atherosclerotic plaque

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Song, H. (2007). Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/28258

Chicago Manual of Style (16^th Edition):

Song, Hannah. “Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis.” 2007. Doctoral Dissertation, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/28258.

MLA Handbook (7^th Edition):

Song, Hannah. “Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis.” 2007. Web. 06 Mar 2021.

Vancouver:

Song H. Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis. [Internet] [Doctoral dissertation]. Georgia Tech; 2007. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/28258.

Council of Science Editors:

Song H. Endothelial bone morphogenic protein 4 and bone morphogenic protein receptor II expression in inflammation and atherosclerosis. [Doctoral Dissertation]. Georgia Tech; 2007. Available from: http://hdl.handle.net/1853/28258

Georgia Tech

6. Wu, Jingshu. Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force.

Degree: PhD, Mechanical Engineering, 2010, Georgia Tech

URL: http://hdl.handle.net/1853/33858

► Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in… (more)

▼ Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in physical science. In general, the rheology of particle suspension is quite complex, and the problem becomes even more complicated if the suspending particle is deformable. Despite these difficulties, a large number of theoretical and experimental investigations have been devoted to the analysis and prediction of the rheological behavior of particle suspensions. However, among these studies there are very few investigations that focus on the role of particle deformability. A novel method for full coupling of the fluid-solid phases with sub-grid accuracy for the solid phase is developed. In this method, the flow is computed on a fixed regular 'lattice' using the lattice Boltzmann method (LBM), where each solid particle, or fiber, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the particle are obtained from Newtonian dynamics equations. The deformable particle is modeled by the lattice-spring model (LSM).The fiber deformation is calculated by an efficient flexible fiber model. The no-slip boundary condition at the fluid-solid interface is based on the external boundary force (EBF) method. This method is validated by comparing with known experimental and theoretical results. The fiber simulation results show that the rheological properties of flexible fiber suspension are highly dependent on the microstructural characteristics of the suspension. It is shown that fiber stiffness (bending ratio BR) has strong impact on the suspension rheology in the range BR < 3. The relative viscosity of the fiber suspension under shear increases significantly as BR decreases. Direct numerical simulation of flexible fiber suspension allows computation of the primary normal stress difference as a function of BR. These results show that the primary normal stress difference has a minimum value at BR ∼ 1. The primary normal stress differences for slightly deformable fibers reaches a minimum and increases significantly as BR decreases below 1. The results are explained based on the Batchelor's relation for non-Brownian suspensions. The influence of fiber stiffness on the fiber orientation distribution and orbit constant is the major contributor to the variation in rheological properties. A least-squares curve-fitting relation for the relative viscosity is obtained for flexible fiber suspension. This relation can be used to predict the relative viscosity of flexible fiber suspension based on the result of rigid fiber suspension. The unique capability of the LBM-EBF method for sub-grid resolution and multiscale analysis of particle suspension is applied to the challenging problem of platelet motion in blood flow. By computing the stress distribution over the platelet, the "blood damage index" is computed and compared with experiments in channels with various geometries [43]. In platelet simulation, the effect of 3D channel… Advisors/Committee Members: Cyrus K. Aidun (Committee Chair), Ajit P. Yoganathan (Committee Co-Chair), Marc K. Smith (Committee Member), S. Mostafa Ghiaasiaan (Committee Member), Thorsten Stoesser (Committee Member), Victor Breedveld (Committee Member).

Subjects/Keywords: Lattice-Boltzmann; Numerical simulation; Flexible fiber; External boundary force; Deformable particles; Suspension rheology; Suspensions (Chemistry); Particles; Rheology; Deformations (Mechanics); Mathematical models

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Wu, J. (2010). Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/33858

Chicago Manual of Style (16^th Edition):

Wu, Jingshu. “Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force.” 2010. Doctoral Dissertation, Georgia Tech. Accessed March 06, 2021. http://hdl.handle.net/1853/33858.

MLA Handbook (7^th Edition):

Wu, Jingshu. “Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force.” 2010. Web. 06 Mar 2021.

Vancouver:

Wu J. Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force. [Internet] [Doctoral dissertation]. Georgia Tech; 2010. [cited 2021 Mar 06]. Available from: http://hdl.handle.net/1853/33858.

Council of Science Editors:

Wu J. Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force. [Doctoral Dissertation]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/33858

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