scholarly journals oxLDL increases endothelial stiffness, force generation and network formation

2006 ◽  
Vol 45 (3) ◽  
pp. e73
Author(s):  
Fitzroy J. Byfield ◽  
George H. Rothblat ◽  
Keith J. Gooch ◽  
Irena Levitan
Keyword(s):  
Network Formation ◽  
Force Generation ◽  
Endothelial Stiffness

scholarly journals OxLDL increases endothelial stiffness, force generation, and network formation

2006 ◽  
Vol 47 (4) ◽  
pp. 715-723 ◽  
Author(s):  
Fitzroy J. Byfield ◽  
Saloni Tikku ◽  
George H. Rothblat ◽  
Keith J. Gooch ◽  
Irena Levitan
Keyword(s):  
Network Formation ◽  
Force Generation ◽  
Endothelial Stiffness

scholarly journals oxLDL-induced decrease in lipid order of membrane domains is inversely correlated with endothelial stiffness and network formation

2010 ◽  
Vol 299 (2) ◽  
pp. C218-C229 ◽  
Author(s):  
Tzu Pin Shentu ◽  
Igor Titushkin ◽  
Dev K. Singh ◽  
Keith J. Gooch ◽  
Papasani V. Subbaiah ◽  
...  
Keyword(s):  
Network Formation ◽  
Cell Stiffness ◽  
Membrane Domains ◽  
Collagen Gels ◽  
Lipid Packing ◽  
Angiogenic Potential ◽  
Cell Contractility ◽  
Lipid Order ◽  
The Impact ◽  
Endothelial Stiffness

Oxidized low-density lipoprotein (oxLDL) is a major factor in development of atherosclerosis. Our earlier studies have shown that exposure of endothelial cells (EC) to oxLDL increases EC stiffness, facilitates the ability of the cells to generate force, and facilitates EC network formation in three-dimensional collagen gels. In this study, we show that oxLDL induces a decrease in lipid order of membrane domains and that this effect is inversely correlated with endothelial stiffness, contractility, and network formation. Local lipid packing of cell membrane domains was assessed by Laurdan two-photon imaging, endothelial stiffness was assessed by measuring cellular elastic modulus using atomic force microscopy, cell contractility was estimated by measuring the ability of the cells to contract collagen gels, and EC angiogenic potential was estimated by visualizing endothelial networks within the same gels. The impact of oxLDL on endothelial biomechanics and network formation is fully reversed by supplying the cells with a surplus of cholesterol. Furthermore, exposing the cells to 7-keto-cholesterol, a major oxysterol component of oxLDL, or to another cholesterol analog, androstenol, also results in disruption of lipid order of membrane domains and an increase in cell stiffness. On the basis of these observations, we suggest that disruption of lipid packing of cholesterol-rich membrane domains plays a key role in oxLDL-induced changes in endothelial biomechanics.

scholarly journals Oxldl-Induced Decrease in Lipid Order of Membrane Domains is Inversely Correlated with Endothelial Stiffness and Network Formation

2010 ◽  
Vol 98 (3) ◽  
pp. 366a
Author(s):  
Tzu-Pin Shentu ◽  
Igor Titushkin ◽  
Dev K. Singh ◽  
Keith J. Gooch ◽  
Papasani Subbaiah ◽  
...  
Keyword(s):  
Network Formation ◽  
Membrane Domains ◽  
Lipid Order ◽  
Endothelial Stiffness

Platelet Microtubules in Clot Structure Formation and Contractile Force Generation: Investigation of a Controversy

1986 ◽  
Vol 56 (01) ◽  
pp. 023-027 ◽  
Author(s):  
C J Jen ◽  
L V McIntire
Keyword(s):  
Network Formation ◽  
Contractile Force ◽  
Second Phase ◽  
Clot Retraction ◽  
Forming Process ◽  
Microtubule Organization ◽  
Physiological Processes ◽  
Fibrin Network ◽  
Two Parameters

SummaryWhether platelet microtubules are involved in clot retraction/ contraction has been controversial. To address this question we have simultaneously measured two clotting parameters, clot structural rigidity and isometric contractile force, using a rheological technique. For recalcified PRP clots these two parameters began rising together at about 15 min after CaCl2 addition. In the concentration range affecting microtubule organization in platelets, colchicine, vinca alkaloids and taxol demonstrated insignificant effects on both clotting parameters of a recalcified PRP clot. For PRP clots induced by adding small amounts of exogenous thrombin, the kinetic curves of clot rigidity were biphasic and without a lag time. The first phase corresponded to a platelet-independent network forming process, while the second phase corresponded to a platelet-dependent process. These PRP clots began generating contractile force at the onset of the second phase. For both rigidity and force parameters, only the second phase of clotting kinetics was retarded by microtubule affecting reagents. When PRP samples were clotted by adding a mixture of CaCl2 and thrombin, the second phase clotting was accelerated and became superimposed on the first phase. The inhibitory effects of micro tubule affecting reagents became less pronounced. Thrombin clotting of a two-component system (washed platelets/ purified fibrinogen) was also biphasic, with the second phase being microtubule-dependent. In conclusion, platelet microtubules are important in PRP clotted with low concentrations of thrombin, during which fibrin network formation precedes platelet-fibrin interactions. On the other hand they are unimportant if a PRP clot is induced by recalcification, during which the fibrin network is constructed in the presence of platelet-fibrin interactions. The latter is likely to be more analogous to physiological processes in vivo.

Lack of myostatin in mice results in excessive muscle but impaired force generation, tubular aggregates and alterations in fibre type profile

2005 ◽  
Vol 36 (02) ◽  
Author(s):  
H Amthor ◽  
R Navarette ◽  
SC Brown ◽  
R Macharia ◽  
F Muntoni ◽  
...  
Keyword(s):  
Fibre Type ◽  
Force Generation ◽  
Tubular Aggregates

Some Consequences of Coulomb Friction in Modeling Longitudinal Traction

1990 ◽  
Vol 18 (1) ◽  
pp. 13-65 ◽  
Author(s):  
W. W. Klingbeil ◽  
H. W. H. Witt
Keyword(s):  
Shear Force ◽  
Coulomb Friction ◽  
Interfacial Shear ◽  
Force Generation ◽  
Behavior Patterns ◽  
Inflation Pressure ◽  
Friction Law ◽  
The Coefficient Of Friction ◽  
Coulomb Friction Law ◽  
Perfect Adhesion

Abstract A three-component model for a belted radial tire, previously developed by the authors for free rolling without slip, is generalized to include longitudinal forces and deformations associated with driving and braking. Surface tractions at the tire-road interface are governed by a Coulomb friction law in which the coefficient of friction is assumed to be constant. After a brief review of the model, the mechanism of interfacial shear force generation is delineated and explored under traction with perfect adhesion. Addition of the friction law then leads to the inception of slide zones, which propagate through the footprint with increasing severity of maneuvers. Different behavior patterns under driving and braking are emphasized, with comparisons being given of sliding displacements, sliding velocities, and frictional work at the tire-road interface. As a further application of the model, the effect of friction coefficient and of test variables such as load, deflection, and inflation pressure on braking stiffness are computed and compared to analogous predictions on the braking spring rate.

Israel’s Ground Forces in the Occupied Territories

2020 ◽  
Vol 35 (2) ◽  
pp. 37-57
Author(s):  
Eyal Ben-Ari ◽  
Uzi Ben-Shalom
Keyword(s):  
High Intensity ◽  
Force Generation ◽  
Institutional Autonomy ◽  
Multiple Forms ◽  
The West ◽  
Occupied Territories ◽  
Media Monitoring ◽  
Israel Defense Forces ◽  
And Control ◽  
Over Time

The Israel Defense Forces (IDF) routinely rotate ground forces in and out of the Occupied Territories in the West Bank. While these troops are trained for soldiering in high-intensity wars, in the Territories they have long had to carry out a variety of policing activities. These activities often exist in tension with their soldierly training and ethos, both of which center on violent encounters. IDF ground forces have adapted to this situation by maintaining a hierarchy of ‘logics of action’, in which handling potentially hostile encounters takes precedence over other forms of policing. Over time, this hierarchy has been adapted to the changed nature of contemporary conflict, in which soldiering is increasingly exposed to multiple forms of media, monitoring, and juridification. To maintain its public legitimacy and institutional autonomy, the IDF has had to adapt to the changes imposed on it by creating multiple mechanisms of force generation and control of soldierly action.

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