scholarly journals Elucidation of Regional Mechanical Properties of Brain Tissues Based on Cell Density

2021 ◽  
Vol 18 (3) ◽  
pp. 611-622
Author(s):  
Chi Zhang ◽  
Long Qian ◽  
Hongwei Zhao
Keyword(s):  
Mechanical Properties ◽  
Cerebral Cortex ◽  
Shear Modulus ◽  
Brain Tissue ◽  
Unit Area ◽  
Neuronal Cell ◽  
Occipital Lobe ◽  
Element Model ◽  
Cellular Density ◽  
Neuronal Cell Bodies

AbstractResearch on the mechanical properties of brain tissue has received extensive attention. However, most of the current studies have been conducted at the phenomenological level. In this study, the indentation method was used to explore the difference in local mechanical properties among different regions of the porcine cerebral cortex. Further, hematoxylin-eosin and immunofluorescence staining methods were used to determine the correlation between the cellular density at different test points and mechanical properties of the porcine cerebral cortex. The frontal lobe exhibited the strongest viscosity. The temporal lobe displayed the lowest sensitivity to changes in the indentation speed, and the occipital lobe exhibited the highest shear modulus. Additionally, the shear modulus of different areas of the cerebral cortex was negatively correlated with the total number of local cells per unit area and positively correlated with the number of neuronal cell bodies per unit area. Exploration of the mechanical properties of the local brain tissue can provide basic data for the establishment of a finite element model of the brain and mechanical referential information for the implantation position of brain chips.

Viscoelastic Property Changes of Acute Rat Brain Tissue Slices as a Function of Cell Viability

2011 ◽  
Author(s):  
Sung Jin Lee ◽  
Jingjing Sun ◽  
Michael King ◽  
Huikai Xie ◽  
Malisa Sarntinoranont
Keyword(s):  
Mechanical Properties ◽  
Cerebral Cortex ◽  
Shear Modulus ◽  
Cell Viability ◽  
Rat Brain ◽  
Brain Tissue ◽  
Cell Membrane Permeability ◽  
Tissue Slices ◽  
Rat Brain Tissue ◽  
Brain Tissues

Changes in mechanical properties within brain tissues after losses in cell viability have not been well investigated. Lack of oxygen and nutrient transport can induce hypoxic neuronal injury and increase cell membrane permeability, and cell membranes and matrix components can lose their structural and mechanical integrity. These physical changes may have an effect on mechanical properties of brain tissue [1]. In this study, the viscoelastic behavior of two anatomical regions (cerebral cortex and hippocampus) in acute rat brain tissue slices were measured as a function of cell viability using indentation combined with optical coherence tomography (OCT). Neuronal viability in brain tissue slices was determined by measuring Fluoro-Jade C (FJC) staining to assay neuronal death or degeneration as a function of incubation time. OCT-measured deformation depths were compared with finite element (FE) simulations to estimate the relaxation of shear modulus. Measured equilibrium shear modulus (μ∞) after 8 hrs incubation was lower than μ∞ measured after 2 hrs incubation in the cerebral cortex (μ∞, 2hrs = 225 Pa, μ∞, 8hrs = 62 Pa) and hippocampus regions (μ∞, 2hrs = 170 Pa, μ∞, 8hrs = 33 Pa). Instantaneous shear modulus (μ0) after 8 hrs incubation was also an order of magnitude lower than μ0 after 2 hrs incubation in cortex (μ0, 2hrs = 1600 Pa, μ0, 8hrs = 100 Pa) and hippocampus regions (μ0, 2hrs = 370 Pa, μ0, 8hrs = 70 Pa). The results of this study provide a timeline for measuring mechanical properties of brain tissues ex vivo and provide better understanding of changes in brain modulus after injury or cell death.

scholarly journals Stimulation by acetylcholine of phosphatidylinositol labelling. Subcellular distribution in rat cerebral-cortex slices

1972 ◽  
Vol 126 (5) ◽  
pp. 1141-1147 ◽  
Author(s):  
Eduardo G. Lapetina ◽  
Robert H. Michell
Keyword(s):  
Cerebral Cortex ◽  
Specific Radioactivity ◽  
Neuronal Cell ◽  
Subcellular Fractionation ◽  
Rat Cerebral Cortex ◽  
Marker Enzymes ◽  
Fresh Tissue ◽  
Cell Structures ◽  
Neuronal Cell Bodies ◽  
Cortex Slices

1. Rat cerebral-cortex slices were incubated with 32Pi, acetylcholine and eserine for periods of 10min and 2h. The specific radioactivity of phosphatidylinositol was elevated during these treatments by 36 and 106% respectively. 2. The specific radioactivities of the phosphatidylinositol in different cell structures were determined after subcellular fractionation. They were highest in the nuclear, microsomal and synaptic-vesicle fractions and lowest in myelin, both in the controls and in the acetylcholine-treated slices. 3. The stimulated labelling of phosphatidylinositol was relatively evenly distributed: no subcellular fraction showed a stimulation markedly higher than that in the homogenate. 4. Studies of the distributions and activities of marker enzymes indicated that the subcellular fractionation achieved was similar to that with fresh tissue. 5. The results are discussed in relation to the previous report that the stimulation is observed throughout the neuronal cell-bodies and in relation to the hypothesis that the labelled phosphatidylinositol produced by stimulation is a component of an acetylcholine-receptor proteolipid localized in the synaptic junction.

Cortex: Topography and Organization

2021 ◽  
pp. 175-178
Author(s):  
Richard J. Caselli ◽  
David T. Jones
Keyword(s):  
Cerebral Cortex ◽  
Visual Cortex ◽  
Gray Matter ◽  
Striate Cortex ◽  
Neuronal Cell ◽  
Area 17 ◽  
Neuronal Cell Bodies ◽  
Brodmann Areas ◽  
Functional Components ◽  
Complex Activities

The cerebral cortex is involved in various simple and complex activities. It consists of layers of neuronal cell bodies (ie, gray matter) that are organized into gyri (convolutions).The cortex can be divided into functional components in several ways. Various schemes are based on function, cytoarchitecture, topography, or Brodmann areas. The terminology can be confusing because the same area of cortex could be designated by several names. For instance, Brodmann area 17 is also called the primary visual cortex, the striate cortex, and the calcarine cortex. Brodmann designated 52 regions of the cerebral cortex according to cytoarchitecture.

Variations in Mechanical Properties of Wood Plates Due Fluctuations on Relative Humidity of Air

2012 ◽  
Vol 1372 ◽  
Author(s):  
J. A. Torres ◽  
M. De Icaza ◽  
R. R. Boullosa
Keyword(s):  
Mechanical Properties ◽  
Relative Humidity ◽  
Shear Modulus ◽  
Natural Frequencies ◽  
Element Model ◽  
Quantitative Information ◽  
Musical Instruments ◽  
Similar Frequency ◽  
Natural Variations ◽  
Set Up

ABSTRACTOften, mechanical properties of wood plates are accurately approximated through orthotropic characterization. However, the numerical values may show considerable variations in the case of real wood plates immersed in fluctuant environmental conditions, especially if the relative humidity of air (RH) is changing. Problems arising from the natural variations in RH have been reported on making musical instruments. In this work, the influence of changing RH on the mechanical properties of a guitar’s top plate (clamped on its contour) has been measured. Vibratory responses of the plate were experimentally obtained, through forced vibration, while data were recorded for several RH values, without any alteration in the experimental set-up devices. The six lowest natural frequencies of the structure were extracted from peaks detected in the responses. Natural frequencies depend on mass distribution and mechanical properties of the structure. For the highest sensed RH (67 %), each natural frequency of the plate decreased at least in 11 Hz compared with reference values measured at the lowest sensed RH (53 %). To determine the connection between the shift in natural frequencies and the changes in the wood elastic and shear modulus, a finite element model of the plate was performed. It was useful calculating natural frequencies through simulated modal analyses. Elastic and shear modulus were handled to match simulated results with experimental natural frequencies recorded for a RH=53% level. These elastic moduli must be decreased around 10 % to obtain a similar frequency decrease in the experimental natural frequencies obtained under a RH=67% level. The experimental results show quantitative information on an interaction scarcely researched, that is, the modification on mechanical properties of wood plates induced by RH variations. Sensed changes due this wood-air interaction are responsible of a modification in the behavior of musical instruments, as guitars and violins.

The Red Neuronal Pigment in the Nervous System of the Mussel, Mytilus Edulis: Localization and Its Effect on Lateral Ciliary Activity with Spectral and Analytical Changes

1981 ◽  
Vol 39 ◽  
pp. 494-495
Author(s):  
Anthony A. Paparo ◽  
Judith A. Murphy
Keyword(s):  
Nervous System ◽  
Mytilus Edulis ◽  
Neuronal Cell ◽  
Ciliary Activity ◽  
Neuronal Cell Bodies ◽  
The Central Nervous System ◽  
Intracellular Organelles ◽  
The Common ◽  
The Individual ◽  
Cryostat Sections

The purpose of this study was to localize the red neuronal pigment in Mytilus edulis and examine its role in the control of lateral ciliary activity in the gill. The visceral ganglia (Vg) in the central nervous system show an over al red pigmentation. Most red pigments examined in squash preps and cryostat sec tions were localized in the neuronal cell bodies and proximal axon regions. Unstained cryostat sections showed highly localized patches of this pigment scattered throughout the cells in the form of dense granular masses about 5-7 um in diameter, with the individual granules ranging from 0.6-1.3 um in diame ter. Tissue stained with Gomori's method for Fe showed bright blue granular masses of about the same size and structure as previously seen in unstained cryostat sections.Thick section microanalysis (Fig.l) confirmed both the localization and presence of Fe in the nerve cell. These nerve cells of the Vg share with other pigmented photosensitive cells the common cytostructural feature of localization of absorbing molecules in intracellular organelles where they are tightly ordered in fine substructures.

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

2019 ◽  
Vol 107 (2) ◽  
pp. 207 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Miroslav Karlík ◽  
Veronika Kadlecová ◽  
Jiří Čapek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Young’S Modulus ◽  
Milling Time ◽  
Young's Modulus ◽  
Element Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Particles ◽  
Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

Adaptogenic correction of free radical brain damage in subchronic exposure to sodium fl uoride

2020 ◽  
pp. 381-386
Author(s):  
A. G. Zhukova ◽  
L. G. Gorokhova ◽  
A. S. Kazitskaya ◽  
T. K. Yadykina ◽  
N. N. Mikhailova ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Free Radical ◽  
Brain Tissue ◽  
Free Radical Oxidation ◽  
Radical Oxidation ◽  
Free Radical Processes ◽  
Subchronic Exposure ◽  
Antioxidant Defense Enzymes ◽  
Radical Processes ◽  
Complex Drug

Introduction. Fluorine compounds in small doses, but with prolonged exposure, cause various disorders in organs at the cellular and molecular levels. Activation of free-radical processes plays an important role in the damaging eff ect of fl uorides. Th erefore, one of the most eff ective ways to limit fl uorine-induced damage is to directly aff ect free-radical processes using herbal preparations with antioxidant properties.The aim of the study is to study the eff ect of a dihydroquercetin-based drug on the activity of free radical processes in brain tissue under subchronic exposure to sodium fl uoride (NaF).Materials and methods. Th e work was performed on white male laboratory rats weighing 200-250 g. Th e rats were divided into 3 groups: 1 — control; 2 — rats with chronic exposure to sodium fl uoride (NaF) for 9 weeks; 3 — rats receiving a NAF solution with simultaneous administration of a complex drug based on dihydroquercetin at a dose of 3 mg/kg in 1% starch gel for 3, 6 and 9 weeks. The activity of free radical oxidation and antioxidant defense enzymes — superoxide dismutase (SOD) and catalase-was determined in the cerebral cortex. Th e level of expression of hypoxia-induced transcription factor HIF — 1A and inducible forms of proteins HSP72 and HSP32 were determined in the cytosolic fraction of brain tissue.Results. In the early stages of subchronic fl uoride exposure (1-3 weeks), the expression of protective proteins HIF-1α, HSP72, HSP32 and catalase was shown in the rat cortex, as a result of which the activity of free-radical processes was maintained at the control level. An increase in the timing of fl uoride intake to 9 weeks led to a decrease in antioxidant protection and signifi cant activation of free radical oxidation in brain tissue. Daily administration of a complex drug with dihydroquercetin for 3, 6 and 9 weeks to rats with subchronic fl uoride exposure led to a decrease in the severity of pro- and antioxidant balance disorders in the cerebral cortex. At the same time, the greatest protective eff ect of dihydroquercetin with fl uoride exposure was manifested by the 9th week of its administration.Conclusions. When subchronic intake of fl uorides in the body, the drug based on dihydroquercetin has a neuroprotective eff ect, which is manifested by an increase in the activity of antioxidant enzymes of fr ee radical oxidation and catalase and the resistance of the cortex to induced fr ee radical oxidation.

Effect of Dynamic Crosslinking on Mechanical Properties of PP/EPDM Blends

1993 ◽  
Vol 58 (11) ◽  
pp. 2642-2650 ◽  
Author(s):  
Zdeněk Kruliš ◽  
Ivan Fortelný ◽  
Josef Kovář
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Shear Modulus ◽  
High Impact ◽  
Necessary Condition ◽  
Step Method ◽  
Melt Mixing ◽  
One Step ◽  
High Impact Strength ◽  
Dynamic Curing

The effect of dynamic curing of PP/EPDM blends with sulfur and thiuram disulfide systems on their mechanical properties was studied. The results were interpreted using the knowledge of the formation of phase structure in the blends during their melt mixing. It was shown, that a sufficiently slow curing reaction is necessary if a high impact strength is to be obtained. Only in such case, a fine and homogeneous dispersion of elastomer can be formed, which is the necessary condition for high impact strength of the blend. Using an inhibitor of curing in the system and a one-step method of dynamic curing leads to an increase in impact strength of blends. From the comparison of shear modulus and impact strength values, it follows that, at the stiffness, the dynamically cured blends have higher impact strength than the uncured ones.

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