34 research outputs found
ΠΠ»Π΅ΠΊΡΡΠΎΠΌΠ°Π³Π½ΠΈΡΠ½Π°Ρ ΠΎΠ±ΡΡΠ°Π½ΠΎΠ²ΠΊΠ° Π² ΠΊΠΎΠΌΠΏΡΡΡΠ΅ΡΠ½ΡΡ ΠΊΠ»Π°ΡΡΠ°Ρ , Π΅Π΅ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ Π½ΠΎΡΠΌΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ
ΠΡΠΈΠ²Π΅Π΄Π΅Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½ΡΠ°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠΉ ΠΎΠ±ΡΡΠ°Π½ΠΎΠ²ΠΊΠΈ (ΠΠΠ), ΡΠΎΠ·Π΄Π°Π²Π°Π΅ΠΌΠΎΠΉ ΠΊΠΎΠΌΠΏΡΡΡΠ΅ΡΠ°ΠΌΠΈ Π² ΡΡΠ΅Π±Π½ΡΡ
ΠΏΠΎΠΌΠ΅ΡΠ΅Π½ΠΈΡΡ
. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ Π² Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΎΡ ΠΌΠ΅ΡΡΠ° ΡΠ°ΡΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΊΠΎΠΌΠΏΡΡΡΠ΅ΡΠ° ΠΌΠ΅Π½ΡΡΡΡΡ ΡΠ°Π·ΠΌΠ΅ΡΡ, ΡΠΎΠ·Π΄Π°Π²Π°Π΅ΠΌΠΎΠΉ ΠΈΠΌ Π·ΠΎΠ½Ρ ΠΎΠΏΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΈΠ·Π»ΡΡΠ΅Π½ΠΈΡ, Π΄Π°Π½Ρ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄Π°ΡΠΈΠΈ ΠΏΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ ΠΠΠ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Π°ΠΌ Π΅Π΅ Π½ΠΎΡΠΌΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ
Does the osteocyte lacuna affect bone adaptive response in aging?
Klein Nulend, J. [Promotor]Lenthe, G.H. van [Promotor]Bakker, A.D. [Copromotor
Elastic moduli of carbon nanotubes with new geometry based on FEM
In this paper, the elastic moduli of elliptic single walled carbon nanotubes (ESWCNTs)
are described. A three-dimensional finite element (FE) model for such carbon nanotubes is
proposed. The covalent bonds are simulated by beam elements in the FE model. The elastic
moduli of beam elements are ascertained from a linkage between molecular and continuum
mechanics. The deformations of the FE model are subsequently used to predict the elastic
moduli of ESWCNTs. In order to demonstrate the FE performance, the influence of length,
chirality, diameter and cross sectional aspect ratios on the elastic moduli (Youngβs modulus
and shear modulus) of ESWCNTs is investigated. It is found that the cross sectional aspect
ratio of ESWCNTs significantly affects the elastic moduli. With increasing cross sectional
aspect ratio, the Youngβs modulus and shear modulus decrease. As a result, every change in
geometry operates as a defect and decreases the elastic moduli. With increasing the length,
Youngβs modulus increases and the shear modulus decreases
Electronic control of H+ current in a bioprotonic device with carbon nanotube porins.
Hybrid biotic abiotic devices can be used to interface electronics with biological systems for novel therapies or to increase device functionality beyond silicon. Many strategies exist to merge the electronic and biological worlds, one dominated by electrons and holes as charge carriers, the other by ions. In the biological world, lipid bilayers and ion channels are essential to compartmentalize the cell machinery and regulate ionic fluxes across the cell membrane. Here, we demonstrate a bioelectronic device in which a lipid bilayer supported on H+-conducting Pd/PdHx contacts contains carbon nanotubes porin (CNTP) channels. This bioelectronic device uses CNTPs to control of H+ flow across the lipid bilayer with a voltage applied to the Pd/PdHx contacts. Potential applications of these devices include local pH sensing and control
Aging, osteocytes, and mechanotransduction
Purpose of Review: The bone is able to adapt its structure to mechanical signals via the bone remodeling process governed by mechanosensitive osteocytes. With aging, an imbalance in bone remodeling results in osteoporosis. In this review, we hypothesized that changes in lacunar morphology underlie the decreased bone mechanoresponsiveness to mechanical loading with aging. Recent Findings: Several studies have reported considerable variations in the shape of osteocytes and their lacunae with aging. Since osteocytes can sense matrix strain directly via their cell bodies, the variations in osteocyte morphology may cause changes in osteocyte mechanosensitivity. As a consequence, the load-adaptive response of osteocytes may change with aging, even when mechanical loading would remain unchanged. Summary: Though extensive quantitative data is lacking, evidence exists that the osteocyte lacunae are becoming smaller and more spherical with aging. Future dedicated studies might reveal whether these changes would affect osteocyte mechanosensation and the subsequent biological response, and whether this is (one of) the pathways involved in age-related bone loss
Age-related changes in female mouse cortical bone microporosity
Osteocyte lacunae are small cavities within the bone matrix. Their dimensions and spatial arrangement affect bone mechanical properties. Furthermore, their size and shape affect the strain in bone tissue close to the lacunae; hence, they are supposed to affect the mechanosensory function of the osteocytes residing in the lacunae. It was the purpose of this study to quantify the morphological features of osteocyte lacunae, whether these are affected by aging and whether these vary among different anatomical location. In addition, we aimed at quantifying the vascular canals as these affect bone's microporosity too. We quantified the microporosity in the fibular midshaft of young-adult and old female C57BL/6 mice. Using micro-computed tomography (ΞΌCT), we found that advanced age was associated with a significantly decreased vascular canal number and volume density. In aged mice, the mean volume of the lacuna was significantly smaller than in young animals and they were more round. Lacuna number density close to the neutral axis of the fibula was higher in older mice than in young ones. The characterization of bone microporosity presents a first step in further unraveling their potential role in age-related reductions in bone strength
Mechanical loading differentially affects osteocytes in fibulae from lactating mice compared to osteocytes in virgin mice: Possible role for lacuna size
Hormonal changes during lactation are associated with profound changes in bone cell biology, such as osteocytic osteolysis, resulting in larger lacunae. Larger lacuna shape theoretically enhances the transmission of mechanical signals to osteocytes. We aimed to provide experimental evidence supporting this theory by comparing the mechanoresponse of osteocytes in the bone of lactating mice, which have enlarged lacunae due to osteocytic osteolysis, with the response of osteocytes in bone from age-matched virgin mice. The osteocyte mechanoresponse was measured in excised fibulae that were cultured in hormone-free medium for 24 h and cyclically loaded for 10 min (sinusoidal compressive load, 3000 ¡Ρ, 5 Hz) by quantifying loading-related changes in Sost mRNA expression (qPCR) and sclerostin and β-catenin protein expression (immunohistochemistry). Loading decreased Sost expression by ~ threefold in fibulae of lactating mice. The loading-induced decrease in sclerostin protein expression by osteocytes was larger in lactating mice (55% decrease ± 14 (± SD), n = 8) than virgin mice (33% decrease ± 15, n = 7). Mechanical loading upregulated β-catenin expression in osteocytes in lactating mice by 3.5-fold (± 0.2, n = 6) which is significantly (p < 0.01) higher than the 1.6-fold increase in β-catenin expression by osteocytes in fibulae from virgin mice (± 0.12, n = 4). These results suggest that osteocytes in fibulae from lactating mice with large lacunae may respond stronger to mechanical loading than those from virgin mice. This could indicate that osteocytes residing in larger lacuna show a stronger response to mechanical loading