scholarly journals Emphysema and Mechanical Stress-Induced Lung Remodeling

Physiology ◽  
2013 ◽  
Vol 28 (6) ◽  
pp. 404-413 ◽  
Author(s):  
Béla Suki ◽  
Susumu Sato ◽  
Harikrishnan Parameswaran ◽  
Margit V. Szabari ◽  
Ayuko Takahashi ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Transpulmonary Pressure ◽  
Mechanical Stresses ◽  
Lung Remodeling ◽  
Cell Functions ◽  
New Directions ◽  
Mechanical Factors ◽  
Mechanical Rupture

Transpulmonary pressure and the mechanical stresses of breathing modulate many essential cell functions in the lung via mechanotransduction. We review how mechanical factors could influence the pathogenesis of emphysema. Although the progression of emphysema has been linked to mechanical rupture, little is known about how these stresses alter lung remodeling. We present possible new directions and an integrated multiscale view that may prove useful in finding solutions for this disease.

scholarly journals Magneto- and Tensoresistance of the p Ge Compensated Crystals in the Range of Weak, Intermediate and Classically Strong Magnetic Fields

2016 ◽  
Vol 17 (1) ◽  
pp. 43-47 ◽  
Author(s):  
G.P. Gaidar
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Mechanical Stress ◽  
Elastic Deformation ◽  
Crystallographic Orientation ◽  
Longitudinal Axis ◽  
Mechanical Stresses ◽  
Strong Magnetic Fields ◽  
Compensation Factor

On the crystalsof compensatedp‑Ge (with the compensation factor of k = NSb/NGa = 0.5) the transverse (Н ^ (J // X)) magnetoresistance (within the magnetic fields of 0 < Н £ 22.3 kOe) at fixed values of the mechanical stresses Хі = 0; 0.2; 0.4; 0.6; 0.9; 1.1; 1.5 GPa were measured at 77 K. These mechanical stresses X created the elastic deformation along the samples, the crystallographic orientation of which coincided with the direction of [100]. Also at fixed magnetic field intensities Ні = 2; 4; 8; 10; 15; 20; 22.3 kOe the dependencies of resistivity  on the mechanical stress X, which coincides with the longitudinal axis of the crystal (X // J // [100]) and changes in the range of 0 £ Х £ 1.5 GPa, were measured. Last dependences characterized by the presence of a minimum in the range of X ~ 0.5 ¸ 0.6 GPa at the minimal magnetic field intensities Н = 2 kOe, which was shifted to the values of X ~ 0.2 ¸ 0.3 GPa with increasing Н up to 22.3 kOe.

Development of a novel micro-ablation system to realise micrometric and well-defined hydrogel structures for tissue engineering applications

2014 ◽  
Vol 20 (6) ◽  
pp. 490-498 ◽  
Author(s):  
C. De Maria ◽  
L. Grassi ◽  
F. Vozzi ◽  
A. Ahluwalia ◽  
G. Vozzi
Keyword(s):  
Tissue Engineering ◽  
Cell Culture ◽  
Laser Ablation ◽  
Laser Beam ◽  
Mechanical Stress ◽  
Content Type ◽  
Cell Functions ◽  
Hydrogel Film ◽  
Hydrogel Matrix ◽  
Main Components

Purpose – This paper aims to develop a novel micro-ablation system to realise micrometric and well-defined hydrogel structures. To engineer a tissue it is necessary to evaluate several aspects, such as cell-cell and cell-substrate interactions, its micro-architecture and mechanical stimuli that act on it. For this reason, it is important to fabricate a substrate which presents a microtopology similar to natural tissue and has chemical and mechanical properties able to promote cell functions. In this paper, well-defined hydrogel structures embedding cells were microfabricated using a purposely developed technique, micro-laser ablation, based on a thulium laser. Its working parameters (laser power emission, stepper motor velocity) were optimised to produce shaded “serpentine” pattern on a hydrogel film. Design/methodology/approach – In this study, initially, swelling/contraction tests on agarose and alginate hydrogel in different solutions of main components of cell culture medium were performed and were compared with the MECpH model. This comparison matched with good approximation experimental measurements. Once known how hydrogel changed its topology, microstructures with a well-defined topology were realised using a purposely developed micro-laser ablation system design. S5Y5 neuroblastoma cell lines were embedded in hydrogel matrix and the whole structure was ablated with a laser microfabrication system. The cells did not show damages due to mechanical stress present in the hydrogel matrix and to thermal increase induced by the laser beam. Findings – The hydrogel structure is able to reproduce extracellular matrix. Initially, the hydrogel swelling/contraction in different solutions, containing the main components of the most common cell culture media, was analysed. This analysis is important to evaluate if cell culture environment could alter microtopology of realised structures. Then, the same topology was realised on hydrogel film embedding neuronal cells and the cells did not show damages due to mechanical stress present in the hydrogel matrix and to thermal increase induced by the laser beam. The interesting obtained results could be useful to realise well-defined microfabricated hydrogel structures embedding cells to guide tissue formation Originality/value – The originality of this paper is the design and realisation of a 3D microfabrication system able to microfabricate hydrogel matrix embedding cells without inducing cell damage. The ease of use of this system and its potential modularity render this system a novel potential device for application in tissue engineering and regenerative medicine area.

An experimental investigation on PZT behavior under mechanical and cycling loading

2013 ◽  
Vol 22 (3-4) ◽  
pp. 129-136
Author(s):  
Haim Abramovich ◽  
Eugeny Tsikchotsky ◽  
Gregory Klein
Keyword(s):  
Electric Power ◽  
Mechanical Stress ◽  
Electrical Power ◽  
Electrical Energy ◽  
Mechanical Stresses ◽  
Cyclic Loads ◽  
Present Test ◽  
Static Mechanical ◽  
The Right ◽  
Cycling Loading

AbstractThe drive to produce electrical energy by directly compressing piezoceramic material using mechanical stress stands behind the present test series. To be able to correctly choose the right material, PZT disks manufactured by three different manufacturers have been tested under static mechanical compressive and cyclic loads. It was shown that although the disks can withstand high mechanical stresses (up to 100 MPa) without any visible damage, their transduction is confined to much lower stresses (50–75 MPa), a range in which the electrical output is a function of the square of the applied stress. This range is further reduced, when the PZT is subjected to cyclic mechanical loading, yielding an applicable mechanical stress in the range of 30–40 MPa, from which electrical power can be produced without further deterioration. To compensate for the low electric power, due to relatively low mechanical stresses applied on the PZT disks, one can increase the volume of the material used by placing layers of piezoelectric material one on top of the other, each subjected to the same mechanical stress. This will yield the required electric power from a safe given mechanical stress without reduction in its output.

scholarly journals Methods for evaluation of mechanical stress condition of materials

2018 ◽  
Vol 145 ◽  
pp. 05008 ◽  
Author(s):  
Yordan Mirchev ◽  
Pavel Chukachev ◽  
Mitko Mihovski
Keyword(s):  
Surface Waves ◽  
Mechanical Stress ◽  
Ultrasonic Method ◽  
Mechanical Stresses ◽  
Principal Stresses ◽  
Small Depth ◽  
Type Size ◽  
Cylindrical Holes ◽  
The One ◽  
First Time

Primary attention is given to the following methods: method by drilling cylindrical holes (drill method) and integrated ultrasonic method using volume (longitudinal and transverse), surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.

Modulation of cell functions of human tendon fibroblasts by different repetitive cyclic mechanical stress patterns

2003 ◽  
Vol 55 (2-3) ◽  
pp. 153-158 ◽  
Author(s):  
Tanja Barkhausen ◽  
Martijn van Griensven ◽  
Johannes Zeichen ◽  
Ulrich Bosch
Keyword(s):  
Mechanical Stress ◽  
Cell Functions ◽  
Human Tendon ◽  
Stress Patterns

scholarly journals Matrix modulation of compensatory lung regrowth and progenitor cell proliferation in mice

2010 ◽  
Vol 298 (2) ◽  
pp. L158-L168 ◽  
Author(s):  
A. M. Hoffman ◽  
A. Shifren ◽  
M. R. Mazan ◽  
A. M. Gruntman ◽  
K. M. Lascola ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Mechanical Stress ◽  
Progenitor Cells ◽  
Stress Responses ◽  
Transpulmonary Pressure ◽  
Alveolar Epithelial Cells ◽  
Clara Cell ◽  
Physical Factors ◽  
Clara Cells ◽  
Elastic Recoil

Mechanical stress is an important modulator of lung morphogenesis, postnatal lung development, and compensatory lung regrowth. The effect of mechanical stress on stem or progenitor cells is unclear. We examined whether proliferative responses of epithelial progenitor cells, including dually immunoreactive (CCSP and proSP-C) progenitor cells (CCSP+/SP-C+) and type II alveolar epithelial cells (ATII), are affected by physical factors found in the lung of emphysematics, including loss of elastic recoil, reduced elastin content, and alveolar destruction. Mice underwent single lung pneumonectomy (PNY) to modulate transpulmonary pressure (mechanical stress) and to stimulate lung regeneration. Control mice underwent sham thoracotomy. Plombage of different levels was employed to partially or completely abolish this mechanical stress. Responses to graded changes in transpulmonary pressure were assessed in elastin-insufficient mice (elastin +/−, ELN+/−) and elastase-treated mice with elastase-induced emphysema. Physiological regrowth, morphometry (linear mean intercept; Lmi), and the proliferative responses of CCSP+/SP-C+, Clara cells, and ATII were evaluated. Plombage following PNY significantly reduced transpulmonary pressure, regrowth, and CCSP+/SP-C+, Clara cell, and ATII proliferation following PNY. In the ELN+/− group, CCSP+/SP-C+ and ATII proliferation responses were completely abolished, although compensatory lung regrowth was not significantly altered. In contrast, in elastase-injured mice, compensatory lung regrowth was significantly reduced, and ATII but not CCSP+/SP-C+ proliferation responses were impaired. Elastase injury also reduced the baseline abundance of CCSP+/SP-C+, and CCSP+/SP-C+ were found to be displaced from the bronchioalveolar duct junction. These data suggest that qualities of the extracellular matrix including elastin content, mechanical stress, and alveolar integrity strongly influence the regenerative capacity of the lung, and the patterns of cell proliferation in the lungs of adult mice.

Silvicultural control of mechanical stresses in trees

1988 ◽  
Vol 18 (10) ◽  
pp. 1215-1225 ◽  
Author(s):  
Hans Kubler
Keyword(s):  
Spatial Distribution ◽  
Mechanical Stress ◽  
High Stress ◽  
Growth Conditions ◽  
Mechanical Stresses ◽  
Reaction Wood ◽  
Prevailing Wind ◽  
Growth Stresses ◽  
Stable Growth ◽  
Steep Slopes

Mechanical stress generated by growing wood cells causes heart checks in the ends of timber, while lumber end-splits and warps. It is not possible to prevent these growth stresses but they can be minimized. Trees generate relatively high stress in order to bend stems and branches into positions more favorable for the tree, as is known from reaction wood, whose growth stresses are extremely high. One controls the stresses by giving trees no reason to reorient themselves, that is, by providing stable growth conditions. To this end, trees should have sufficient, uniform light, and where light is scarce, as in understories, one-sided light changes have to be avoided. In particular, the spatial distribution of trees in the stand should be uniform; multistoried forests are preferable to single-storied, even-aged plantations. The stands should be thinned slightly, frequently, and uniformly, rather than haphazardly and severely after long periods. In areas with strong prevailing wind, close spacing may minimize the stresses, whereas on steep slopes wide spacing appears to be preferable.

Proposal of a Mechano-Cell Model With Membrane, Cytoskeleton and Nucleus

2008 ◽  
Author(s):  
Masanori Nakamura ◽  
Ray Noguchi ◽  
Yoshihiro Ujihara ◽  
Hiroshi Miyazaki ◽  
Shigeo Wada
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mechanical Stress ◽  
Cell Shape ◽  
Cell Model ◽  
Cell Functions ◽  
Membrane Cytoskeleton ◽  
A Cell ◽  
Loading Tests ◽  
Intracellular Structure

The mechanical properties of cells have been of great interest to scientists from early studies which suggested that mechanical stress-induced alterations in cell shape and structure are critical for control of many cell functions. Although various loading tests of a cell have been designed to understand the cellular mechanical properties, the heterogeneous intracellular structure such as cytoskeletons brings about difficulties in interpreting experimental data.

Flow increases superoxide production by NADPH oxidase via activation of Na-K-2Cl cotransport and mechanical stress in thick ascending limbs

2007 ◽  
Vol 292 (3) ◽  
pp. F993-F998 ◽  
Author(s):  
Nancy J. Hong ◽  
Jeffrey L. Garvin
Keyword(s):  
Nadph Oxidase ◽  
Mechanical Stress ◽  
Mechanical Strain ◽  
Cell Types ◽  
Mechanical Forces ◽  
Free Solution ◽  
Luminal Flow ◽  
Mechanical Factors ◽  
Tubular Flow ◽  
Isolated Rat

Superoxide (O2−) regulates renal function and is implicated in hypertension. O2− production increases in response to increased ion delivery in thick ascending limbs (TALs) and macula densa and mechanical strain in other cell types. Tubular flow in the kidney acutely varies causing changes in ion delivery and mechanical stress. We hypothesized that increasing luminal flow stimulates O2− production by NADPH oxidase in TALs via activation of Na-K-2Cl cotransport. We measured intracellular O2− in isolated rat TALs using dihydroethidium in the presence and absence of luminal flow and inhibitors of NADPH oxidase, Na-K-2Cl cotransport, and Na/H exchange. In the absence of flow, the rate of O2− production was 5.8 ± 1.4 AU/s. After flow was initiated, it increased to 29.7 ± 4.3 AU/s ( P < 0.001). O2− production was linearly related to flow. Tempol alone and apocynin alone blocked the flow-induced increase in O2− production (3.5 ± 1.7 vs. 4.5 ± 2.8 AU/s and 8.2 ± 2.1 vs. 10.6 ± 2.8 AU/s, respectively). Furosemide decreased flow-induced O2− production by 55% (37.3 ± 5.2 to 16.8 ± 2.8 AU/s; P < 0.002); however, dimethylamiloride had no effect. Finally, we examined whether changes in mechanical forces are involved in flow-induced O2− production by using a Na-free solution to perfuse TALs. In the absence of NaCl, luminal flow enhanced O2− production (1.5 ± 0.5 to 13.5 ± 1.1 AU/s; P < 0.001), ∼50% less stimulation than when flow was increased in the presence of luminal NaCl. We conclude that flow stimulates O2− production in TALs via activation of NADPH oxidase and that NaCl absorption due to Na-K-2Cl cotransport and flow-associated mechanical factors contribute equally to this process.

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