Role of Mechanical Factors in the Aetiology, Pathogenesis and Progression of Osteoarthritis

ABSTRACTCommon processes used in glazed ceramic production often result in a glaze with a heterogeneous microstructure. Heterogeneities may be due to residual batch materials, intentionally added colorants and opacifiers and/or the products of devitrification and phase separation. To study the effect of heterogeneities in the corrosion process, dynamic imaging microellipsometry was used in-situ in aqueous solutions to measure spatially and temporally resolved changes in the surface of glasses (model glazes). The measurements showed increased durability near inclusions. Residual stress fields surrounding the heterogeneities influenced the results. Decoupling of chemical and mechanical factors causing this increased durability was not possible.

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Role of Aspirin Resistance, Mechanical Factors and Inflammation on Early Saphenous Vein Graft Thrombosis After CABG

10.21203/rs.3.rs-551134/v1 ◽

2021 ◽

Author(s):

Dudy Arman hanafy ◽

Budhi Setianto Setianto ◽

Jusuf Rachmat ◽

Soesanto ◽

Arman Adel Abdullah ◽

...

Keyword(s):

Saphenous Vein ◽

Vein Graft ◽

Graft Failure ◽

Saphenous Vein Graft ◽

Aspirin Resistance ◽

Primary Role ◽

Flow Measurements ◽

Graft Thrombosis ◽

Mechanical Factors

Abstract Objectives: This study was carried out to determine the role of pre-operative and transient aspirin resistance in the formation of early saphenous vein graft (SVG) thrombosis six weeks after coronary artery bypass graft (CABG) surgery and to analyze the other factors, such as mechanical and inflammation factors, that are also suspected of contributing to the formation of early thrombosis.Methods: Pre- and post-operative blood samples were taken from 99 subjects, whom 74 patients were undergoing elective on-pump CABG and receiving aspirin as monotherapy, for evaluation of inflammation parameters and the state of aspirin resistance using a Platelet Function Analyzer-200 (PFA-200). Transit time flow measurements (TTFM) were performed intra-operatively to determine mechanical factors. Multi-sliced computed tomography (MSCT) was done six weeks after surgery to determine the patency of the vein grafts.Result: In the 222 vein conduits, aspirin resistance was related to early vein graft failure due to thrombosis (p < 0.001; relative risk (RR) = 3.69). The massive increase of interleukin 6 (IL-6) levels after surgery were related to the existence of post-operative transient aspirin resistance (p < 0.001). Transient aspirin resistance (IL-6 > 122.5) was associated with early graft failure (p = 0.029; RR = 8.6) compared to the aspirin-sensitive group (IL-6 > 122.5).Conclusion: Aspirin resistance plays a primary role in early vein graft thrombosis. Transient aspirin resistance accompanied by an increase of inflammation factor (IL-6) significantly increases the risk of early vein graft thrombosis after CABG.

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The role of oxygen transport in atherosclerosis and vascular disease

Journal of The Royal Society Interface ◽

10.1098/rsif.2019.0732 ◽

2020 ◽

Vol 17 (165) ◽

pp. 20190732 ◽

Cited By ~ 3

Author(s):

John Tarbell ◽

Marwa Mahmoud ◽

Andrea Corti ◽

Luis Cardoso ◽

Colin Caro

Keyword(s):

Blood Flow ◽

Vascular Disease ◽

Oxygen Transport ◽

Intimal Hyperplasia ◽

Hypoxia Inducible Factor ◽

Vascular Diseases ◽

Vascular Wall ◽

Vasa Vasorum ◽

Mechanical Factors

Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system—the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.

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Relationships between pressure and flow across the gastroduodenal junction in dogs

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.260.4.g653 ◽

1991 ◽

Vol 260 (4) ◽

pp. G653-G657 ◽

Cited By ~ 4

Author(s):

C. H. Malbert ◽

Y. Ruckebusch

Keyword(s):

Flow Rate ◽

Temporal Relationship ◽

Conscious Dogs ◽

Transpyloric Flow ◽

Gastric Contents ◽

Mechanical Factors

Antroduodenal pressure events were measured simultaneously with transpyloric flow, in conscious dogs, to evaluate the role of mechanical factors modulating this flow. The relationships between pressure and flow across the gastroduodenal junction were never linear. During the interdigestive state, terminal antral contraction occurred 0.9 +/- 0.29 s after the onset of the gush of gastric contents. Hence, the highest flow rate occurred during the period of lowest resistance. After a meal, terminal antral contraction began 3.3 +/- 0.87 s before the flow of chyme, and resistance rose simultaneously with flow rate. The antroduodenal resistance was 10 times higher than during the interdigestive state (8.33 +/- 1.56 vs. 0.73 +/- 0.34 mmHg.ml-1.s). The pyloroduodenal resistance was always lower than the antropyloric one. It is concluded that, because of the temporal relationship between motor events and flow, pure resistive behavior of the junction occurred only after a meal.

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Mechanical factors and the regulation of perfusion through atelectatic lung in pigs

Journal of Applied Physiology ◽

10.1152/jappl.1982.52.3.647 ◽

1982 ◽

Vol 52 (3) ◽

pp. 647-654 ◽

Cited By ~ 6

Author(s):

S. Enjeti ◽

P. B. Terry ◽

H. A. Menkes ◽

R. J. Traystman

Keyword(s):

Blood Flow ◽

Vascular Conductance ◽

Hemodynamic Responses ◽

Closed Chest ◽

Open Chest ◽

Regional Hemodynamics ◽

Mechanical Factors

The role of mechanical interdependence in the perfusion of atelectatic lung was studied in two ways: a) regional hemodynamics were compared before (control) and after the development of lobar and sublobar atelectasis, and b) the effect of thoracotomy on regional hemodynamics was assessed. With lobar atelectasis mean lobar blood flow and vascular conductance decreased to 60% of control. Sublobar atelectasis caused mean sublobar blood flow and vascular conductance to decrease to 6% of control. Opening the chest after production of lobar atelectasis caused blood flow to fall to 50% of control. When sublobar atelectasis was produced in the open chest, sublobar blood flow decreased to 25% of control measurements made prior to thoracotomy. We conclude that with a closed chest, sublobar vascular distortion mediated by mechanical interdependence may be an important mechanism responsible for the differences in hemodynamic responses to atelectasis between lobes and sublobar regions.

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Role of mechanical factors in cortical folding development

Physical Review E ◽

10.1103/physreve.92.032701 ◽

2015 ◽

Vol 92 (3) ◽

Cited By ~ 15

Author(s):

Mir Jalil Razavi ◽

Tuo Zhang ◽

Xiao Li ◽

Tianming Liu ◽

Xianqiao Wang

Keyword(s):

Cortical Folding ◽

Mechanical Factors

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Biomechanics of the Lumbar Disc

Journal of Musculoskeletal Research ◽

10.1142/s0218957797000104 ◽

1997 ◽

Vol 01 (02) ◽

pp. 81-94 ◽

Cited By ~ 3

Author(s):

V. K. Goel ◽

N. M. Grosland ◽

J. Scifert

Keyword(s):

Morphological Changes ◽

Imaging Techniques ◽

Lumbar Disc ◽

Analytical Models ◽

Clinical Observations ◽

Disc Bulge ◽

Mechanical Factors ◽

Methods Analytical

The human disc and the facets work in unison to transmit loads across a lumbar motion segment. For this reason, if one component is affected by the degenerative process, the other follows. Modern imaging techniques and clinical observations have adequately delineated morphological changes in the spinal structures, while in vitro biomechanical studies have revealed that repetitive complex loads may lead to loosening of spinal structures, annular tears, and herniated discs. In addition to such experimental methods, analytical models have been able to explain the role of mechanical factors in producing disc degeneration and herniation. Furthermore, these techniques are applicable to investigating various surgical stabilization procedures. From a biomechanical perspective, surgical procedures such as discectomy are effective in reducing pain due to a decrease in disc bulge following surgery. Excessive instability across the disc, however, may require the use of bone grafts, cages or other types of interbody spacers to restore disc height. Efforts are currently underway to restore disc mechanics via an artificial disc. The following review is aimed at outlining the role of mechanical foctors in both inducing and stabilizing the degenerated/herniated intervertebral disc.

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Human endolymphatic sac: possible mechanisms of pressure regulation

The Journal of Laryngology & Otology ◽

10.1017/s0022215100102713 ◽

1987 ◽

Vol 101 (8) ◽

pp. 768-779 ◽

Cited By ~ 17

Author(s):

Phillip Ashley Wackym ◽

Ulla Friberg ◽

Dan Bagger-Sjöbäck ◽

Fred H. Linthicum ◽

Imrich Friedmann ◽

...

Keyword(s):

Electron Microscopy ◽

Experimental Studies ◽

Secretory Activity ◽

Regulatory Mechanisms ◽

Endolymphatic Sac ◽

Pressure Regulation ◽

Transmission Electron ◽

Normal Human ◽

Mechanical Factors

AbstractThe ultrastructure of the normal human endolymphatic sac (ES) has been observed by transmission electron microscopy (TEM). The role of the epithelium, the various regions of the subepithelial space and the general anatomy of the ES in pressure regulation were morphologically studied to generate testable hypotheses of human ES function. Light microscopic (LM) and TEM evidence of pressure regulatory mechanisms by endolymph resorption, mechanical factors, and secretory activity are presented. These mechanisms may be useful in designing experimental studies of the ES, and in interpretation of retrospective LM and TEM studies of patients with Meniere's disease.

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