The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Daniel M. Espino - One of the best experts on this subject based on the ideXlab platform.
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articular cartilage surface rupture during compression investigating the effects of Tissue Hydration in relation to matrix health
Journal of The Mechanical Behavior of Biomedical Materials, 2011Co-Authors: James M. Fick, Daniel M. EspinoAbstract:This study aimed at investigating articular cartilage rupture by investigating the response of healthy and degenerate cartilage through altering the osmotic swelling environment of surface-intact, cartilage-on-bone specimens. The osmotic environment in healthy and degenerate bovine cartilage was varied by soaking Tissues in either distilled water or 1.5 M NaCl saline to render the Tissues into a swollen or dehydrated state (respectively). Creep compression was applied using an 8 mm flat-ended polished indenter that contained a central pore of 450 μm diameter, providing a consistent region for rupture to occur across all specimens. In the first set of experiments, surface rupture of healthy and degenerate specimens required similar levels of nominal compressive stress (8 MPa) when dehydrated than when swollen (7 MPa). In the second set of experiments, the time required for surface rupture to occur (for healthy and degenerate specimens) occurred over similar loading times (p>0.05). However, the time required for surface rupture for the swollen specimens occurred over a significantly longer time (approximately one order of magnitude) than that required for the dehydrated specimens (p<0.05). The compressive strains that were measured at rupture in the dehydrated degenerate specimens were significantly lower than those measured in the dehydrated healthy Tissues (p<0.05). Rupture in dehydrated degenerate cartilage suggested a weakened articular surface, and it also suggested that dehydrated cartilage may undergo failure due to stress concentrations as it is unable to redistribute stress away from the site of loading.
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Articular cartilage surface rupture during compression: investigating the effects of Tissue Hydration in relation to matrix health.
Journal of the mechanical behavior of biomedical materials, 2011Co-Authors: James M. Fick, Daniel M. EspinoAbstract:This study aimed at investigating articular cartilage rupture by investigating the response of healthy and degenerate cartilage through altering the osmotic swelling environment of surface-intact, cartilage-on-bone specimens. The osmotic environment in healthy and degenerate bovine cartilage was varied by soaking Tissues in either distilled water or 1.5 M NaCl saline to render the Tissues into a swollen or dehydrated state (respectively). Creep compression was applied using an 8 mm flat-ended polished indenter that contained a central pore of 450 μm diameter, providing a consistent region for rupture to occur across all specimens. In the first set of experiments, surface rupture of healthy and degenerate specimens required similar levels of nominal compressive stress (8 MPa) when dehydrated than when swollen (7 MPa). In the second set of experiments, the time required for surface rupture to occur (for healthy and degenerate specimens) occurred over similar loading times (p>0.05). However, the time required for surface rupture for the swollen specimens occurred over a significantly longer time (approximately one order of magnitude) than that required for the dehydrated specimens (p
A. Shkurinov - One of the best experts on this subject based on the ideXlab platform.
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Clinical Application of Terahertz Reflectometry for Sensing of Corneal Tissue and Tear Film
2018 International Conference Laser Optics (ICLO), 2018Co-Authors: I. Ozheredov, M. Mischenko, M. Prokopchuk, T. Saphonova, E. Sikach, E. Balakin, P. Solyankin, A. ShkurinovAbstract:Terahertz frequency-domain reflectometry is applied for sensing of human corneal Tissue Hydration level and dynamical control of the tear film in clinical applications.
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In vivo THz sensing of the cornea of the eye
Laser Physics Letters, 2018Co-Authors: I. Ozheredov, M. Mischenko, M. Prokopchuk, P. Solyankin, A. A. Angeluts, Alexei V. Balakin, Tatiana Safonova, Andrey V. Larichev, A. ShkurinovAbstract:Measurement of the absolute value of the humidity of the cornea of the human eye and its dynamics is of paramount importance for the preservation of eyesight. In the present paper we have demonstrated that terahertz technologies can be practically applied for quantitative measurement of the physiological dynamics of tear film and sensing of corneal Tissue Hydration. We suggest uses of the equipment for application in clinics and a method for absolute calibration of the values for measurement. The proposed method is fundamentally different from existing and currently available methods of ophthalmological diagnosis. This suggests that the developed technique may have high diagnostic significance and can be used in the study and treatment of several diseases of the ocular surface.
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Terahertz reflectometry for the corneal Tissue Hydration sensing
2016 International Conference Laser Optics (LO), 2016Co-Authors: A. A. Angeluts, I. Ozheredov, T. Saphonova, Alexei V. Balakin, M. D. Mishchenko, A. ShkurinovAbstract:The cornea is one of the most important external structure of the human eye. Its transparency is an important factor for visual function and depends on the Tissue Hydration. For cornea Hydration sensing we use terahertz reflectometer based on difference frequency generation of a pair of continuous semiconductor lasers. Spectral sensitive measurements are obtained by fine frequency tuning of terahertz source.
R. L. Kamman - One of the best experts on this subject based on the ideXlab platform.
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Changes in 31P-relaxation times during organ preservation: observations on cold stored human donor livers.
Magnetic resonance imaging, 1997Co-Authors: R. F. E. Wolf, Maarten J.h. Slooff, R. L. KammanAbstract:During cold preservation for transplantation the Tissue Hydration state changes. It is not known whether such changes lead to altered relaxation times of 31P nuclei with potential consequences for the quantification of Tissue metabolites. Therefore, 31P spectroscopic and proton T1 relaxometric measurements were performed on 42 isolated human donor livers shortly before implantation. The results demonstrate that 31P T1 relaxation times change during preservation for clinical transplantation, thus quantification of Tissue metabolites in cold stored donor livers may be in part dependent on the Tissue Hydration state. Furthermore, it appeared that changes in Tissue Hydration state especially affect the physico-chemical characteristics of the intracellular fluid compartment. This study indicates that reliable spectroscopic quantification of Tissue metabolites, particularly during sequential spectroscopic measurements in cold stored donor organs is best warranted under fully relaxed conditions.
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Tissue Hydration in kidneys during preservation : A relaxometric analysis of time-dependent differences between cortex and medulla
Transplant International, 1996Co-Authors: J. A. B. Van Der Hoeven, I. J. De Jong, R. F. E. Wolf, R. L. Kamman, Rutger J. PloegAbstract:Cold preservation of donor organs induces hypothermia-related Tissue edema as a result of a reduced activity of the ATP-dependent sodium pump at low temperatures. Hypothermia-induced Tissue edema occurs in kidney preservation and is a significant risk factor for delayed graft function (DGF) after transplantation. DGF remains a major problem in kidney transplantation and is significantly associated with preservation injury. The state of Hydration of cold-stored organs can be assessed from a biopsy for determination of the wet/dry weight ratio. As a non-invasive method to determine Tissue Hydration MRI T1 and T2 relaxometry can be used. In this study we have compared changes in Tissue Hydration in UW-preserved porcine kidneys with increasing cold ischemia times (CIT) using wet/dry weight ratio and MR ralaxometry. The results of the two techniques were correlated to evaluate the use of MR relaxometry. Wet/dry weight ratios of the renal cortex decreased with prolonged CIT (P < 0.01) whereas those of the medulla did not change significantly. T1 values of the cortex decreased with prolonged CIT (P < 0.01). T2 values of the cortex showed a non-significant decline with increased CIT. No significant changes in T1 and T2 were found in the medulla. The correlation between T1 and the wet/dry weight ratio of the cortex was significant (P = 0.05, linear correlation coefficient 0.8698). We conclude that MR relaxometry can be a valuable noninvasive technique to assess Tissue Hydration in cadaveric donor kidneys before transplantation.
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The Tissue Hydration state in UW-preserved human donor livers. A clinical study of the relation between proton magnetic resonance relaxation times, donor condition, preservation procedure, and early graft function.
Transplantation, 1994Co-Authors: R. F. E. Wolf, R. L. Kamman, G. Den Butter, H. P. Deketh, W. J. Sluiter, Maarten J.h. SlooffAbstract:To determine the relation between Tissue Hydration state-as indicated by Tissue proton magnetic resonance relaxation times-in UW-preserved human donor livers and viability parameters of the donor and early graft function, ''ex vivo'' magnetic resonance relaxometry was performed with a clinical MR imaging system. Relaxometric data were obtained from MR images in which signal intensities were directly proportional to T-1 and T-2. Forty three subsequently transplanted livers and five discarded livers were studied. The donor serum concentrations of direct and total bilirubin had a positive correlation with T-1 (P
R. F. E. Wolf - One of the best experts on this subject based on the ideXlab platform.
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Changes in 31P-relaxation times during organ preservation: observations on cold stored human donor livers.
Magnetic resonance imaging, 1997Co-Authors: R. F. E. Wolf, Maarten J.h. Slooff, R. L. KammanAbstract:During cold preservation for transplantation the Tissue Hydration state changes. It is not known whether such changes lead to altered relaxation times of 31P nuclei with potential consequences for the quantification of Tissue metabolites. Therefore, 31P spectroscopic and proton T1 relaxometric measurements were performed on 42 isolated human donor livers shortly before implantation. The results demonstrate that 31P T1 relaxation times change during preservation for clinical transplantation, thus quantification of Tissue metabolites in cold stored donor livers may be in part dependent on the Tissue Hydration state. Furthermore, it appeared that changes in Tissue Hydration state especially affect the physico-chemical characteristics of the intracellular fluid compartment. This study indicates that reliable spectroscopic quantification of Tissue metabolites, particularly during sequential spectroscopic measurements in cold stored donor organs is best warranted under fully relaxed conditions.
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Tissue Hydration in kidneys during preservation : A relaxometric analysis of time-dependent differences between cortex and medulla
Transplant International, 1996Co-Authors: J. A. B. Van Der Hoeven, I. J. De Jong, R. F. E. Wolf, R. L. Kamman, Rutger J. PloegAbstract:Cold preservation of donor organs induces hypothermia-related Tissue edema as a result of a reduced activity of the ATP-dependent sodium pump at low temperatures. Hypothermia-induced Tissue edema occurs in kidney preservation and is a significant risk factor for delayed graft function (DGF) after transplantation. DGF remains a major problem in kidney transplantation and is significantly associated with preservation injury. The state of Hydration of cold-stored organs can be assessed from a biopsy for determination of the wet/dry weight ratio. As a non-invasive method to determine Tissue Hydration MRI T1 and T2 relaxometry can be used. In this study we have compared changes in Tissue Hydration in UW-preserved porcine kidneys with increasing cold ischemia times (CIT) using wet/dry weight ratio and MR ralaxometry. The results of the two techniques were correlated to evaluate the use of MR relaxometry. Wet/dry weight ratios of the renal cortex decreased with prolonged CIT (P < 0.01) whereas those of the medulla did not change significantly. T1 values of the cortex decreased with prolonged CIT (P < 0.01). T2 values of the cortex showed a non-significant decline with increased CIT. No significant changes in T1 and T2 were found in the medulla. The correlation between T1 and the wet/dry weight ratio of the cortex was significant (P = 0.05, linear correlation coefficient 0.8698). We conclude that MR relaxometry can be a valuable noninvasive technique to assess Tissue Hydration in cadaveric donor kidneys before transplantation.
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The Tissue Hydration state in UW-preserved human donor livers. A clinical study of the relation between proton magnetic resonance relaxation times, donor condition, preservation procedure, and early graft function.
Transplantation, 1994Co-Authors: R. F. E. Wolf, R. L. Kamman, G. Den Butter, H. P. Deketh, W. J. Sluiter, Maarten J.h. SlooffAbstract:To determine the relation between Tissue Hydration state-as indicated by Tissue proton magnetic resonance relaxation times-in UW-preserved human donor livers and viability parameters of the donor and early graft function, ''ex vivo'' magnetic resonance relaxometry was performed with a clinical MR imaging system. Relaxometric data were obtained from MR images in which signal intensities were directly proportional to T-1 and T-2. Forty three subsequently transplanted livers and five discarded livers were studied. The donor serum concentrations of direct and total bilirubin had a positive correlation with T-1 (P
Sinerik Ayrapetyan - One of the best experts on this subject based on the ideXlab platform.
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The Radioactive 45 Ca Cannot Be Used for Adequate Estimation of the Functional Activity of 40 Ca Ions in Cells and Organisms
Open Journal of Biophysics, 2020Co-Authors: Anna Nikoghosyan, Armenuhi Heqimyan, Lilia Narinyan, Sinerik AyrapetyanAbstract:Previously we have shown that nM ouabain-induced activation of cAMP-dependent Na/Ca exchange in reverse (R) mode in cell membrane has age-dependent weakening Hydration effect on heart muscle and brain Tissues and such Na/Ca exchange is characterized by quantum mechanical sensitivity. As in biological experiments radioactive 45Ca is used for the study of cold 40Ca exchange in cells and organisms, in the present work, the age-dependent effect of physiological solution (PS) containing either 40Ca or 45Ca on Tissue Hydration in different experimental conditions was studied in order to evaluate the bioequivalence of these two forms of Ca. The obtained data indicate that the intraperitoneal injections of 40Ca PS and 45Ca PS leading to activation of RNa/40Ca and RNa/45Ca exchanges, respectively, have different age-dependent effects on heart muscle and brain Tissue Hydration. As in myocyte membrane, the Na/Ca exchange is more expressed than in neuronal membrane, the age-dependent heart muscle Hydration is more sensitive to quantum properties of Ca than brain Tissue Hydration. The [45Ca]i, in contrary to [40Ca]i, has age-dependent weakening and stabilizing effect on Tissue Hydration and makes the latter insensitive to ouabain. The obtained data bring us to a strong conclusion that RNa/Ca exchange has quantum mechanical properties and in biological experiments radioactive 45Ca cannot be used for adequate estimation of the functional activity of 40Ca ions in cells and organisms.
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Age-Dependent Comparative Study of 4 Hz and 8 Hz EMF Exposure on Heart Muscle Tissue Hydration of Rats
Open Journal of Biophysics, 2019Co-Authors: Lilia Narinyan, Sinerik AyrapetyanAbstract:Previously we have shown that 4 Hz and 8 Hz EMF exposures have depressing effect on the thermodynamic activity of water, which decreases peroxide formation. It has also been shown that 4 Hz EMF-treated physiological solution modulates the growth and development of microbes and heart muscle contractility, but 8 Hz EMF has pronounced inhibitory effect on bacterial growth and development. Therefore, in order to elucidate the possible mechanism of 4 Hz and 8 Hz EMF effects on heart muscle function, in the present work the effects of 4 Hz and 8 Hz EMF exposures on heart muscle Tissue Hydration, the sensitivity of 4 Hz and 8 Hz EMF-induced Tissue Hydration to 10−4 M ouabain (Na+/K+ pump inhibition) and 10−9 M ouabain (activation of intracellular signaling system) as well as the effects of 4 Hz and 8 Hz EMF exposures on the number of Na+/K+ pump units in the membrane of both young and old rats have been studied. The obtained data allow us to suggest that 8 Hz EMF exposure has more pronounced age-dependent modulation effect on Tissue Hydration of heart muscle than 4 Hz EMF and this effect is sensitive to Na+/K+ pump activity and intracellular signaling system.
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4Hz mechanical vibration relieves pain through Na+/K+-ATPase α3 isoform-dependent brain Tissue deHydration
International Journal of Basic and Applied Sciences, 2017Co-Authors: Gohar Musheghyan, Arevik Minasyan, Gohar Arajyan, Sinerik AyrapetyanAbstract:In this work the effect of 4Hz 30dB horizontal mechanical vibration (MV) on thermal pain threshold, Hydration and [ 3 H]-ouabain binding in brain and heart muscle Tissues of rats was studied. It was revealed that 4Hz MV treatment for 10 minutes increased pain threshold, which was accompanied by brain and heart muscle Tissue deHydration. In vitro state, Hydration of brain and heart muscle Tissues of sham animals was increased, while in 4Hz MV-treated animals the increase of brain Tissue Hydration was more pronounced and heart muscle Tissues were dehydrated. The fact that 4Hz MV treatment also impacted heart muscle Tissue Hydration indicates that 4Hz MV effect on brain and heart muscle Tissues is realized through a common messenger circulating in blood. The incubation of brain and heart muscle Tissues in PS containing 10 -4 M and 10 -9 M ouabain led to Tissue Hydration in sham and 4Hz MV-treated animals. However, Tissues of 4Hz MV-treated animals were less hydrated, and this Hydration was accompanied by the decrease and increase of membrane receptors’ affinity at 10 -4 M and 10 -9 M ouabain concentrations, respectively. Based on the obtained data, it is suggested that pain-relieving effect of 4Hz MV is due to α 3 isoform-dependent brain Tissue deHydration.
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The Comparative Study of 8Hz EMF Effect on Tissue Hydration in Brain Cortex and Subcortex of Rats
Advances in life sciences, 2017Co-Authors: Sinerik Ayrapetyan, Armenuhi Heqimyan, Anna NikoghosyanAbstract:Previously we have shown that 8Hz EMF has depressing effect on thermodynamic activity of water, which decreases peroxide formation, and 8Hz EMF-treated aqua solution depresses the growth and development of microbes in aqua medium. Therefore, in order to elucidate the possible mechanism of 8Hz EMF on brain function, in the present work the studies of 8Hz EMF exposure effect on brain Tissue Hydration, the sensitivity of 8Hz EMF-induced Tissue Hydration to 10-4M ouabain (Na+/K+ pump inhibition) and 10-9M ouabain (activation of intracellular signaling system) as well as 8Hz EMF exposure effect on the number of Na+/K+ pump units in the membrane of both young and old rats have been performed. The obtained data allow us to suggest that 8Hz EMF exposure has age-dependent modulation effect on brain Tissue Hydration and this effect is sensitive to Na+/K+ pump activity and intracellular signaling system. It has been shown that, in spite of the fact that the number of expressed Na+/K+ pump units in cell membrane of subcortex is significantly less expressed than in cortex cells, the sensitivity of signaling system controlling cell Hydration to 8Hz EMF in subcortex cells is more pronounced than in cortex ones.
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Non-thermal microwave radiation-induced brain Tissue deHydration as a potential factor for brain functional impairment
International Journal of Basic and Applied Sciences, 2016Co-Authors: Anna Nikoghosyan, Armenuhi Heqimyan, Sinerik AyrapetyanAbstract:Based on our previous finding that metabolically controlled cell Hydration is sensitive to the changes of physicochemical properties of cell aqua medium, which take place upon the effect of weak physical signals, including microwaves with non-thermal intensity (NT MW), it has been hypothesized that cell aqua medium serves as a primary target for NT MW effect on brain Tissue. To elucidate the nature of the metabolic pathway through which the effect of NT MW-induced changes of physicochemical properties of cell aqua medium modulate cell Hydration, the effects of intraperitoneal (IP) injection of PS treated by NT MW on brain Tissue Hydration, 45 Ca 2+ uptake, [ 3 H]-ouabain binding with cell membrane and intracellular cyclic nucleotides have been studied. The obtained data indicate that PS treated by NT MW through the activation of high affinity ouabain receptors in membrane stimulates cAMP-dependent Na + /Ca 2+ exchange in reverse mode (R), which leads to brain Tissue Hydration in healthy (young) and deHydration in non-healthy (old) rats. As NT MW radiation-induced activation of R Na + /Ca 2+ exchange leads to the increase of intracellular Ca 2+ ([Ca 2+ ] i), it is considered as a potential factor leading to the brain functional impairment, especially when brain metabolic activity is depressed (e.g. during aging).