Mechanics & chemistry of biosystems : MCB最新文献

Remodeling of strain energy function of common bile duct post obstruction. 胆总管梗阻后应变能功能的重构。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01

Quang Dang, Hans Gregersen, Birgitte Duch, Ghassan S Kassab

{"title":"Remodeling of strain energy function of common bile duct post obstruction.","authors":"Quang Dang, Hans Gregersen, Birgitte Duch, Ghassan S Kassab","doi":"","DOIUrl":"","url":null,"abstract":"Biliary duct obstruction is an important clinical condition that affects millions of people worldwide. We have previously shown that the common bile duct (CBD) undergoes significant growth and remodelling post obstruction. The mechanical stress-strain relation is expected to change due to growth and remodeling in response to obstruction and hence pressure-overload. The objective of the present study was to characterize the material properties of the CBD of the sham group and at 3 hours, 12 hours, 2 days, 8 days and 32 days (n=5 in each group) after obstruction. The Fung's exponential strain energy function was used to relate stress to strain of the normal and remodeled ducts. The Marquardt-Levenberg and genetic algorithm methods were used for the determination of material constants for the exponential strain energy function. The elastic constants obtained by the two methods did not differ (p>0.254). We obtained stable and convergent material constants at every time point. The material constant that dictates the nonlinear rate of change in the circumferential stress with respect to strain increased significantly after obstruction acutely in the first 12 hrs., decreased at 2 days and finally increased montonically during the remaining 30 days. The acute initial increase in stiffness was simply due to the elastic response. The chronic remodeling process results in an initial circumferential softening followed by stiffening of the CBD. This study has important clinical significance for patients with CBD obstruction and for endoscopists and surgeons who treat the condition.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2","pages":"53-61"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26097656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Contractile torque as a steering mechanism for orientation of adherent cells. 收缩力矩作为附着细胞方向的导向机制。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01

Dimitrije Stamenović

引用次数: 0

On Eulerian constitutive equations for modeling growth and residual stresses in arteries. 欧拉本构方程在动脉生长和残余应力模拟中的应用。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01

K Y Volokh

{"title":"On Eulerian constitutive equations for modeling growth and residual stresses in arteries.","authors":"K Y Volokh","doi":"","DOIUrl":"","url":null,"abstract":"Recently Volokh and Lev (2005) argued that residual stresses could appear in growing arteries because of the arterial anisotropy. This conclusion emerged from a continuum mechanics theory of growth of soft biological tissues proposed by the authors. This theory included Lagrangian constitutive equations, which were formulated directly with respect to the reference configuration. Alternatively, it is possible to formulate Eulerian constitutive equations with respect to the current configuration and to 'pull them back' to the reference configuration. Such possibility is examined in the present work. The Eulerian formulation of the constitutive equations is used for a study of arterial growth. It is shown, particularly, that bending resultants are developed in the ring cross-section of the artery. These resultants may cause the ring opening or closing after cutting the artery in vitro as it is observed in experiments. It is remarkable that the results of the present study, based on the Eulerian constitutive equations, are very similar to the results of Volokh and Lev (2005), based on the Lagrangian constitutive equations. This strengthens the authors' argument that anisotropy is a possible reason for accumulation of residual stresses in arteries. This argument appears to be invariant with respect to the mathematical description.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2","pages":"77-86"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26096486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Remodeling of strain energy function of common bile duct post obstruction. 胆总管梗阻后应变能功能的重构。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01 DOI: 10.3970/MCB.2005.002.053

Quang Dang, H. Gregersen, B. Duch, G. Kassab

{"title":"Remodeling of strain energy function of common bile duct post obstruction.","authors":"Quang Dang, H. Gregersen, B. Duch, G. Kassab","doi":"10.3970/MCB.2005.002.053","DOIUrl":"https://doi.org/10.3970/MCB.2005.002.053","url":null,"abstract":"Biliary duct obstruction is an important clinical condition that affects millions of people worldwide. We have previously shown that the common bile duct (CBD) undergoes significant growth and remodelling post obstruction. The mechanical stress-strain relation is expected to change due to growth and remodeling in response to obstruction and hence pressure-overload. The objective of the present study was to characterize the material properties of the CBD of the sham group and at 3 hours, 12 hours, 2 days, 8 days and 32 days (n=5 in each group) after obstruction. The Fung's exponential strain energy function was used to relate stress to strain of the normal and remodeled ducts. The Marquardt-Levenberg and genetic algorithm methods were used for the determination of material constants for the exponential strain energy function. The elastic constants obtained by the two methods did not differ (p>0.254). We obtained stable and convergent material constants at every time point. The material constant that dictates the nonlinear rate of change in the circumferential stress with respect to strain increased significantly after obstruction acutely in the first 12 hrs., decreased at 2 days and finally increased montonically during the remaining 30 days. The acute initial increase in stiffness was simply due to the elastic response. The chronic remodeling process results in an initial circumferential softening followed by stiffening of the CBD. This study has important clinical significance for patients with CBD obstruction and for endoscopists and surgeons who treat the condition.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2 1","pages":"53-61"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70240531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interfacial strength of cement lines in human cortical bone. 骨水泥线在人皮质骨中的界面强度。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01 DOI: 10.3970/MCB.2005.002.063

X. N. Dong, Xiaohui Zhang, X. Guo

{"title":"Interfacial strength of cement lines in human cortical bone.","authors":"X. N. Dong, Xiaohui Zhang, X. Guo","doi":"10.3970/MCB.2005.002.063","DOIUrl":"https://doi.org/10.3970/MCB.2005.002.063","url":null,"abstract":"In human cortical bone, cement lines (or reversal lines) separate osteons from the interstitial bone tissue, which consists of remnants of primary lamellar bone or fragments of remodeled osteons. There have been experimental evidences of the cement line involvement in the failure process of bone such as fatigue and damage. However, there are almost no experimental data on interfacial properties of cement lines in human cortical bone. The objective of this study is to design and assemble a precision and computer controlled osteon pushout microtesting system, and to experimentally determine the interfacial strength of cement lines in human cortical bone by performing osteon pushout tests. Thirty specimens were prepared from humeral diaphyses of four human subjects. Twenty specimens were tested under the condition of a small hole in the supporting plate, in which the cement line debonding occurred. The cement line interfacial strength ranged from 5.38 MPa to 10.85 MPa with an average of 7.31 +/- 1.73 MPa. On the other hand, ten specimens were tested under the condition of a large hole in the supporting plate, in which the shear failure inside osteons was observed. The specimens tested under the condition of the large hole resulted in an average shear strength of 73.71 +/- 15.06 MPa, ranging from 45.97 MPa to 93.74 MPa. Therefore, our results suggest that the cement line interface between osteon and interstitial bone tissue is weaker than that between bone tissue lamellae.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2 1","pages":"63-8"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70240591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 37

On Eulerian constitutive equations for modeling growth and residual stresses in arteries. 欧拉本构方程在动脉生长和残余应力模拟中的应用。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01 DOI: 10.3970/MCB.2005.002.077

K. Volokh

{"title":"On Eulerian constitutive equations for modeling growth and residual stresses in arteries.","authors":"K. Volokh","doi":"10.3970/MCB.2005.002.077","DOIUrl":"https://doi.org/10.3970/MCB.2005.002.077","url":null,"abstract":"Recently Volokh and Lev (2005) argued that residual stresses could appear in growing arteries because of the arterial anisotropy. This conclusion emerged from a continuum mechanics theory of growth of soft biological tissues proposed by the authors. This theory included Lagrangian constitutive equations, which were formulated directly with respect to the reference configuration. Alternatively, it is possible to formulate Eulerian constitutive equations with respect to the current configuration and to 'pull them back' to the reference configuration. Such possibility is examined in the present work. The Eulerian formulation of the constitutive equations is used for a study of arterial growth. It is shown, particularly, that bending resultants are developed in the ring cross-section of the artery. These resultants may cause the ring opening or closing after cutting the artery in vitro as it is observed in experiments. It is remarkable that the results of the present study, based on the Eulerian constitutive equations, are very similar to the results of Volokh and Lev (2005), based on the Lagrangian constitutive equations. This strengthens the authors' argument that anisotropy is a possible reason for accumulation of residual stresses in arteries. This argument appears to be invariant with respect to the mathematical description.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2 1","pages":"77-86"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70240603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interfacial strength of cement lines in human cortical bone. 骨水泥线在人皮质骨中的界面强度。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01

X Neil Dong, Xiaohui Zhang, X Edward Guo

{"title":"Interfacial strength of cement lines in human cortical bone.","authors":"X Neil Dong, Xiaohui Zhang, X Edward Guo","doi":"","DOIUrl":"","url":null,"abstract":"In human cortical bone, cement lines (or reversal lines) separate osteons from the interstitial bone tissue, which consists of remnants of primary lamellar bone or fragments of remodeled osteons. There have been experimental evidences of the cement line involvement in the failure process of bone such as fatigue and damage. However, there are almost no experimental data on interfacial properties of cement lines in human cortical bone. The objective of this study is to design and assemble a precision and computer controlled osteon pushout microtesting system, and to experimentally determine the interfacial strength of cement lines in human cortical bone by performing osteon pushout tests. Thirty specimens were prepared from humeral diaphyses of four human subjects. Twenty specimens were tested under the condition of a small hole in the supporting plate, in which the cement line debonding occurred. The cement line interfacial strength ranged from 5.38 MPa to 10.85 MPa with an average of 7.31 +/- 1.73 MPa. On the other hand, ten specimens were tested under the condition of a large hole in the supporting plate, in which the shear failure inside osteons was observed. The specimens tested under the condition of the large hole resulted in an average shear strength of 73.71 +/- 15.06 MPa, ranging from 45.97 MPa to 93.74 MPa. Therefore, our results suggest that the cement line interface between osteon and interstitial bone tissue is weaker than that between bone tissue lamellae.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 2","pages":"63-8"},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26096484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Contractile torque as a steering mechanism for orientation of adherent cells. 收缩力矩作为附着细胞方向的导向机制。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-06-01 DOI: 10.3970/MCB.2005.002.069

D. Stamenović

引用次数: 6

Growth, anisotropy, and residual stresses in arteries. 动脉的生长、各向异性和残余应力。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-01-01

K Y Volokh, Y Lev

引用次数: 0

Shear force at the cell-matrix interface: enhanced analysis for microfabricated post array detectors. 细胞-基质界面的剪切力:微制造柱阵列探测器的增强分析。

Mechanics & chemistry of biosystems : MCB Pub Date : 2005-01-01 DOI: 10.3970/MCB.2005.002.001

Christopher A. Lemmon, N. Sniadecki, Sami Alom Ruiz, J. Tan, L. Romer, Christopher S. Chen

{"title":"Shear force at the cell-matrix interface: enhanced analysis for microfabricated post array detectors.","authors":"Christopher A. Lemmon, N. Sniadecki, Sami Alom Ruiz, J. Tan, L. Romer, Christopher S. Chen","doi":"10.3970/MCB.2005.002.001","DOIUrl":"https://doi.org/10.3970/MCB.2005.002.001","url":null,"abstract":"The interplay of mechanical forces between the extracellular environment and the cytoskeleton drives development, repair, and senescence in many tissues. Quantitative definition of these forces is a vital step in understanding cellular mechanosensing. Microfabricated post array detectors (mPADs) provide direct measurements of cell-generated forces during cell adhesion to extracellular matrix. A new approach to mPAD post labeling, volumetric imaging, and an analysis of post bending mechanics determined that cells apply shear forces and not point moments at the matrix interface. In addition, these forces could be accurately resolved from post deflections by using images of post tops and bases. Image analysis tools were then developed to increase the precision and throughput of post centroid location. These studies resulted in an improved method of force measurement with broad applicability and concise execution using a fully automated force analysis system. The new method measures cell-generated forces with less than 5% error and less than 90 seconds of computational time. Using this approach, we demonstrated direct and distinct relationships between cellular traction force and spread cell surface area for fibroblasts, endothelial cells, epithelial cells and smooth muscle cells.","PeriodicalId":87411,"journal":{"name":"Mechanics & chemistry of biosystems : MCB","volume":"2 1 1","pages":"1-16"},"PeriodicalIF":0.0,"publicationDate":"2005-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70240184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 104