Investigation into the effect of proteoglycan molecules on the tribological properties of cartilage joint tissues

The aim of this research was to investigate the role of the hydrophilic properties of the proteoglycan molecules within the cartilage matrix, on the tribological properties of joint tissues in the mixed and boundary lubricating regime. Bovine articular cartilage, bovine meniscus and bovine cartilage that had been degraded to remove the chondroitin sulphate from its proteoglycans were studied in order to investigate differences in their friction and compression responses. The tissues were tested on a sliding friction rig under nominal contact stresses of 0.5 and 4 MPa. The compression tests were carried out under a 0.8 MPa contact stress. The compression tests showed the cartilage and meniscus deforming at the same rates, but the degraded cartilage deformed more quickly to reach its equilibrium position in a shorter period of time. The friction tests carried out at a constant load revealed the friction of the meniscus rising more rapidly with loading time than the cartilage. The degraded cartilage followed an almost identical curve as the untreated cartilage. Although the reduced proteoglycan content of the degraded cartilage substantially altered the biphasic compression response, it did not have an effect on the frictional properties of the tissue.

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The relation of protein synthesis to chondroitin sulphate biosynthesis in cultured bovine cartilage

Biochemical Journal ◽

10.1042/bj2240977 ◽

1984 ◽

Vol 224 (3) ◽

pp. 977-988 ◽

Cited By ~ 9

Author(s):

D J McQuillan ◽

C J Handley ◽

H C Robinson ◽

K Ng ◽

C Tzaicos ◽

...

Keyword(s):

Protein Synthesis ◽

Culture Medium ◽

Core Protein ◽

Chondroitin Sulphate ◽

Bovine Articular Cartilage ◽

The Core ◽

Elevated Rate ◽

Chain Synthesis ◽

Chondroitin Sulphate Chain ◽

Bovine Cartilage

The effect of cycloheximide on chondroitin sulphate biosynthesis was studied in bovine articular cartilage maintained in culture. Addition of 0.4 mM-cycloheximide to the culture medium was followed, over the next 4h, by a first-order decrease in the rate of incorporation of [35S]sulphate into glycosaminoglycan (half-life, t 1/2 = 32 min), which is consistent with the depletion of a pool of proteoglycan core protein. Addition of 1.0 mM-benzyl beta-D-xyloside increased the rate of incorporation of [35S]sulphate and [3H]acetate into glycosaminoglycan, but this elevated rate was also diminished by cycloheximide. It was concluded that cycloheximide exerted two effects on the tissue; not only did it inhibit the synthesis of the core protein, but it also lowered the tissue's capacity for chondroitin sulphate chain synthesis. Similar results were obtained with chick chondrocytes grown in high-density cultures. Although the exact mechanism of this secondary effect of cycloheximide is not known, it was shown that there was no detectable change in cellular ATP concentration or in the amount of three glycosyltransferases (galactosyltransferase-I, N-acetylgalactosaminyltransferase and glucuronosyltransferase-II) involved in chondroitin sulphate chain synthesis. The sizes of the glycosaminoglycan chains formed in the presence of cycloheximide were larger than those formed in control cultures, whereas those synthesized in the presence of benzyl beta-D-xyloside were consistently smaller, irrespective of the presence of cycloheximide. These results suggest that beta-D-xylosides must be used with caution to study chondroitin sulphate biosynthesis as an event entirely independent of proteoglycan core-protein synthesis, and they also indicate a possible involvement of the core protein in the activation of the enzymes of chondroitin sulphate synthesis.

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Atomistic modeling of tribological properties of Pd and Al nanoparticles on a graphene surface

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.9.115 ◽

2018 ◽

Vol 9 ◽

pp. 1239-1246 ◽

Cited By ~ 5

Author(s):

Alexei Khomenko ◽

Miroslav Zakharov ◽

Denis Boyko ◽

Bo N J Persson

Keyword(s):

Friction Force ◽

Tribological Properties ◽

Contact Area ◽

Sliding Friction ◽

Center Of Mass ◽

Bottom Surface ◽

Atomistic Modeling ◽

Frictional Properties ◽

Al Nanoparticles ◽

Crystalline Domains

Background: The frictional properties of nanoparticles have been studied to gain insight into the fundamental origin of sliding friction. Results: Using molecular dynamics we investigate frictional properties of aluminum and palladium nanoparticles deposited on a graphene layer. We study the time evolution of the total momentum of the system, the total and potential energies, the temperature, the velocity and position of the center of mass, the dimensions of the nanoparticle, and the friction and substrate forces acting on the particle. We also study how the friction force depends on the nanoparticle–graphene contact area and the temperature. Conclusion: The tribological properties of nanoparticles strongly depend on the materials. The particles move in an irregular (saw-like) manner. The averaged friction force depends nearly linearly on the contact area and non-monotonously on temperature. We observe ordered crystalline domains of atoms at the bottom surface of the metal particles, but the peaks of radial distribution function are blurred indicating that the nanoparticles are amorphous or polycrystalline.

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Chondroitin 6-sulphate is required for neuroplasticity and memory in ageing

Molecular Psychiatry ◽

10.1038/s41380-021-01208-9 ◽

2021 ◽

Author(s):

Sujeong Yang ◽

Sylvain Gigout ◽

Angelo Molinaro ◽

Yuko Naito-Matsui ◽

Sam Hilton ◽

...

Keyword(s):

Chondroitin Sulphate ◽

Memory Loss ◽

Memory Deficits ◽

Long Term Potentiation ◽

Aged Mice ◽

Age Related ◽

Term Potentiation ◽

Early Memory

AbstractPerineuronal nets (PNNs) are chondroitin sulphate proteoglycan-containing structures on the neuronal surface that have been implicated in the control of neuroplasticity and memory. Age-related reduction of chondroitin 6-sulphates (C6S) leads to PNNs becoming more inhibitory. Here, we investigated whether manipulation of the chondroitin sulphate (CS) composition of the PNNs could restore neuroplasticity and alleviate memory deficits in aged mice. We first confirmed that aged mice (20-months) showed memory and plasticity deficits. They were able to retain or regain their cognitive ability when CSs were digested or PNNs were attenuated. We then explored the role of C6S in memory and neuroplasticity. Transgenic deletion of chondroitin 6-sulfotransferase (chst3) led to a reduction of permissive C6S, simulating aged brains. These animals showed very early memory loss at 11 weeks old. Importantly, restoring C6S levels in aged animals rescued the memory deficits and restored cortical long-term potentiation, suggesting a strategy to improve age-related memory impairment.

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Investigation of Sliding Friction Pairs With Electro-Pulse Sprayed Micro-Coats

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-63975 ◽

2005 ◽

Cited By ~ 1

Author(s):

Albinas Andriusis ◽

Vytenis Jankauskas ◽

Juozas Padgurskas ◽

Raimundas Rukuiza ◽

Audrius Zunda

Keyword(s):

Tribological Properties ◽

Sliding Friction ◽

Copper Films ◽

Dense Structure ◽

Coating Technology ◽

Conductive Materials ◽

Multi Stage ◽

Wire Conductor ◽

Control Version

Electro-pulse spraying (EPS) is the coating technology of “electric explosion of conductive materials” when high-voltage and powerful impulse flows through a wire conductor. Object of our investigation — tribological properties of sliding pairs with copper micro-coats made by EPS after one time explosion. Small-grained dense structure coat with evaluated thickness about 4–6 ?m was obtained. Tribological tests, performed at marginal lubrication with multi-stage load, shows that using EPS-specimens the value of friction coefficient is lower as control version. At instantaneous setting of load for long-term running the copper films adopts well to the change of load. The wear of friction pairs according to worn mass show that EPS-specimens worn 79% less than CV-specimens. The investigations point out that copper micro-coats have better tribological properties comparing to control version of friction pairs.

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Role of Mo on tribological properties of atmospheric plasma-sprayed Mo-NiCrBSi composite coatings under dry and oil-lubricated conditions

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2017.08.195 ◽

2017 ◽

Vol 727 ◽

pp. 841-850 ◽

Cited By ~ 24

Author(s):

Chao Zhang ◽

Liming Liu ◽

Haifeng Xu ◽

Jinkun Xiao ◽

Ga Zhang ◽

...

Keyword(s):

Tribological Properties ◽

Composite Coatings ◽

Atmospheric Plasma ◽

Plasma Sprayed

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ON THE ROLE OF HISTOMORPHOMETRIC (STEREOLOGICAL) MICROSTRUCTURE PARAMETERS IN THE PREDICTION OF VERTEBRAE COMPRESSION STRENGTH

Image Analysis & Stereology ◽

10.5566/ias.2028 ◽

2019 ◽

Vol 38 (1) ◽

pp. 63 ◽

Cited By ~ 2

Author(s):

Leszek Karol Wojnar ◽

Aneta Gądek-Moszczak ◽

Jacek Pietraszek

Keyword(s):

Compression Strength ◽

Correlation Coefficients ◽

Diagnostic Techniques ◽

Micro Ct ◽

Compression Tests ◽

Mineral Density ◽

3D Images ◽

Microstructure Parameters

The well-documented relation between bone mineral density (BMD) and bone compression strength constitutes the basis for osteoporosis diagnostics and the assessment of fracture risk. Simultaneously, this relation demonstrates a considerable scatter of results as bones of identical mineral density may have significantly different properties. The experimentally confirmed theorem that two materials or tissues of identical microstructure have identical properties leads to the evaluation of various quantitative stereological parameters (also referred to in biomedicine as histomorphology). These parameters, obtained from analysis of 2D or 3D images, have been used in numerous attempts to explain changes in bone strength. Although numerous correlation dependencies, often with high correlation coefficients, were evaluated, we do not know which parameters are worth evaluating, and there is no physical interpretation of these relations. An extended statistical analysis was accomplished on the basis of analysis of 3D images from 23 lumbar (L3) vertebrae scanned with micro-CT and the results of subsequent compression tests. A new parameter called SDF (structure destruction factor) was proposed in order to characterise the quality of 3D trabecular structures, and its significance was demonstrated. The final correlation function, which uses only three stereological parameters, made it possible to predict compression strength with considerable precision. The estimated values correlated very well with the apparent values (correlation coefficient r=0.96). Finally, the stereological parameters most suitable for characterisation of bone compression strength were chosen and a mechanism responsible for the changes in mechanical properties was proposed. The results obtained defined the necessary improvements in diagnostic techniques that would allow for more efficient quantitative microstructure evaluation and guidelines on how to improve treatment of patients with weakened bones.

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Dynamic Analysis of Sliding Friction in a Gear Pair

Volume 4: 9th International Power Transmission and Gearing Conference, Parts A and B ◽

10.1115/detc2003/ptg-48055 ◽

2003 ◽

Cited By ~ 2

Author(s):

Rajendra Gunda ◽

Rajendra Singh

Keyword(s):

Load Distribution ◽

Sliding Friction ◽

Spur Gear ◽

Time Instant ◽

Friction Torque ◽

Speed Ratio ◽

Gear Pair ◽

Mesh Stiffness ◽

Static Mode

Chief objective of this article is to evaluate the role of sliding friction in gear dynamics, and more specifically the effect of the periodic variations in mesh stiffness, load distribution and friction torque during a mesh cycle. A non-unity speed ratio spur gear is considered. Only the torsional degree of freedom of the gear pair, with ideal Coulomb friction law, is analyzed. Previous studies by Vaishya and Singh [1–3] make idealized assumptions about temporal (or spatial) variation of mesh stiffness and load sharing in order to obtain more tractable analytical solutions. In our formulation, an accurate Finite Element/Contact Mechanics analysis code [4] is run in the static mode to compute the mesh stiffness and load distribution at every time instant of the mesh. The computed parametric variation of stiffness is then incorporated into our dynamic formulation that includes frictional torques. Next, we use appropriate numerical techniques to solve for the dynamic response in time domain. This study, though preliminary in nature, examines the effects of pinion speed, coefficient of friction and mean input torque. This, along with work in progress, should yield further insights into the role of friction sources in gear vibro-acoustics.

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