Meniscus is a semilunar fibrocartilaginous tissue, serving important roles in load buffering, stability, lubrication, proprioception, and nutrition of the knee joint. The degeneration and damage of meniscus has been proved to be a risk factor of knee osteoarthritis. Mechanical stimulus is a critical factor of the development, maintenance and repair of the meniscus fibrochondrocytes. However, the mechanism of the mechano-transduction process remains elusive. Here we reported that cyclic hydrostatic compress force (CHCF) treatment promotes proliferation and inhibits apoptosis of the isolated primary meniscus fibrochondrocytes (PMFs), via upregulating the expression level of integrin ?5ß1. Consequently, increased phosphorylated-ERK1/2 and phosphorylated-PI3K, and decreased caspase-3 were detected. These effects of CHCF treatment can be abolished by integrin ?5ß1 inhibitor or specific siRNA transfection. These data indicate that CHCF regulates apoptosis of PMFs via integrin ?5ß1-FAK-PI3K/ERK pathway, which may be an important candidate approach during meniscus degeneration.

• MeSH
• apoptóza účinky léků   fyziologie   MeSH
• buněčný převod mechanických signálů fyziologie   MeSH
• chondrocyty účinky léků   metabolismus   MeSH
• fibroblasty účinky léků   metabolismus   MeSH
• hydrostatický tlak MeSH
• integrin alfa5beta1 antagonisté a inhibitory   metabolismus   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• malá interferující RNA aplikace a dávkování   MeSH
• meniskus cytologie   metabolismus   MeSH
• pevnost v tlaku fyziologie   MeSH
• potkani Sprague-Dawley MeSH
• proliferace buněk fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• integrin alfa5beta1 MeSH
• malá interferující RNA MeSH

Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress-strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress-strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress-strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress-strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.

• Klíčová slova
• hydrostatic load, organic glass, polymethyl methacrylate plastic, translucent element,
• Publikační typ
• časopisecké články MeSH

Knowledge of shear wave velocities in loaded rocks is important in describing elastic anisotropy. A new high-pressure measuring head was designed and constructed for longitudinal and traversal ultrasonic sounding of spherical rock samples in 132 independent directions under hydrostatic pressure up to 60 MPa. The velocity is measured using a pair of P-wave sensors and two pairs of S-wave sensors (TV/RV and TH/RH) with perpendicular polarization. An isotropic glass sphere was used to calibrate the experimental setup. A fine-grained anisotropic quartzite sample was examined using the P- and S-wave ultrasonic sounding. Waveforms are recorded by pairs of TP/RP, TV/RV and TH/RH transducers in a range of confining pressure between 0.1 and 60 MPa. The recorded data showed a shear wave splitting in three basic structural directions of the sample. The measurements proved to be useful in investigating oriented micro-cracks, lattice (LPO) and shape-preferred orientation (SPO) for the bulk elastic anisotropy of anisotropic rocks subjected to hydrostatic pressure.

• Klíčová slova
• Elastic anisotropy, High pressure, Hydrostatic pressure, Longitudinal and shear waves, Ultrasonic sounding,
• Publikační typ
• časopisecké články MeSH

The main goal of this study is to develop a micromechanical model of a particle-filled dental composite focused on the residual stress (RS) field developed during the curing process in its microstructure. A finite element model of a representative volume element of filler and resin was developed, and volumetric shrinkage was simulated during the curing process. Four material models (von Mises plasticity model, Drucker-Prager plasticity model, von Mises plasticity model with stress relaxation and Drucker-Prager plasticity with stress relaxation) of the polymer resin were built to assess the influence of the material model on the resulting internal stress. The relationship between the curing process and the magnitude of the stress components will be described, and an analysis of the post-curing state of the material in particular microstructure locations will be conducted in this study. Obtained RS is comparable to the stresses developed in the material under the external load. The substantial dependence on the choice of material model for resin is to be observed, and the suitability of particular models is discussed.

• Klíčová slova
• FE modelling, dental composite, plasticity, residual stress,
• MeSH
• analýza metodou konečných prvků MeSH
• analýza zatížení zubů * MeSH
• hydrostatický tlak MeSH
• mechanický stres * MeSH
• složené pryskyřice chemie   MeSH
• teoretické modely MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• složené pryskyřice MeSH

Lattice dynamics and stability of four fcc crystals (Al, Ir, Pt and Au) under isotropic (hydrostatic) tensile loading are studied from first principles using the linear response method and the harmonic approximation. The results reveal that, contrary to former expectations, strengths of all the studied crystals are limited by instabilities related to soft phonons with finite or vanishing wavevectors. The critical strains associated with such instabilities are remarkably lower than those related to the volumetric instability. On the other hand, the corresponding reduction of the tensile strength is by 20% at the most. An analysis of elastic stability conditions is also performed and the results obtained by means of both approaches are compared.

• MeSH
• anizotropie MeSH
• chemické modely * MeSH
• kovy chemie   MeSH
• krystalizace * MeSH
• mechanický stres MeSH
• pevnost v tahu MeSH
• počítačová simulace MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kovy MeSH

We present an ab initio and atomistic study of the stress-strain response and elastic stability of the ordered Fe 3 Al compound with the D0 3 structure and a disordered Fe-Al solid solution with 18.75 at.% Al as well as of a nanocomposite consisting of an equal molar amount of both phases under uniaxial loading along the [001] direction. The tensile tests were performed under complex conditions including the effect of the lateral stress on the tensile strength and temperature effect. By comparing the behavior of individual phases with that of the nanocomposite we find that the disordered Fe-Al phase represents the weakest point of the studied nanocomposite in terms of tensile loading. The cleavage plane of the whole nanocomposite is identical to that identified when loading is applied solely to the disordered Fe-Al phase. It also turns out that the mechanical stability is strongly affected by softening of elastic constants C ' and/or C 66 and by corresponding elastic instabilities. Interestingly, we found that uniaxial straining of the ordered Fe 3 Al with the D0 3 structure leads almost to hydrostatic loading. Furthermore, increasing lateral stress linearly increases the tensile strength. This was also confirmed by molecular dynamics simulations employing Embedded Atom Method (EAM) potential. The molecular dynamics simulations also revealed that the thermal vibrations significantly decrease the tensile strength.

• Klíčová slova
• Fe-Al, ab initio, elasticity, nanocomposite, order, stability, superalloys, tensile strength,
• Publikační typ
• časopisecké články MeSH

Adoptive T cell transfer has been shown to be an effective method used to boost tumor-specific immune responses in several types of malignancies. In this study, we set out to optimize the ACT protocol for the experimental treatment of prostate cancer. The protocol includes a pre-stimulation step whereby T cells were primed with autologous dendritic cells loaded with the high hydrostatic pressure-treated prostate cancer cell line, LNCaP. Primed T cells were further expanded in vitro with anti-CD3/CD28 Dynabeads in the WAVE bioreactor 2/10 system and tested for cytotoxicity. Our data indicates that the combination of pre-stimulation and expansion steps resulted in the induction and enrichment of tumor-responsive CD4+ and CD8+ T cells at clinically relevant numbers. The majority of both CD4+ and CD8+ IFN-γ producing cells were CD62L, CCR7 and CD57 negative but CD28 and CD27 positive, indicating an early antigen experienced phenotype in non-terminal differentiation phase. Expanded T cells showed significantly greater cytotoxicity against LNCaP cells compared to the control SKOV-3, an ovarian cancer line. In summary, our results suggest that the ACT approach together with LNCaP-loaded dendritic cells provides a viable way to generate prostate cancer reactive T cell effectors that are capable of mounting efficient and targeted antitumor responses and can be thus considered for further testing in a clinical setting.

• Klíčová slova
• Adoptive T cell therapy, Cancer immunotherapy, Prostate cancer, Tumor-specific T cell expansion,
• MeSH
• aktivace lymfocytů MeSH
• antigeny nádorové imunologie   MeSH
• bioreaktory MeSH
• dendritické buňky imunologie   MeSH
• epitopy T-lymfocytární imunologie   MeSH
• imunoterapie adoptivní metody   MeSH
• interferon gama biosyntéza   imunologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory prostaty imunologie   MeSH
• nádory vaječníků imunologie   MeSH
• regulační T-lymfocyty imunologie   MeSH
• studie případů a kontrol MeSH
• T-lymfocyty - podskupiny imunologie   MeSH
• T-lymfocyty imunologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny nádorové MeSH
• epitopy T-lymfocytární MeSH
• interferon gama MeSH