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Cell sensing and decision-making in confinement: The role of TRPM7 in a tug of war between hydraulic pressure and cross-sectional area.
Zhao, R, Afthinos, A, Zhu, T, Mistriotis, P, Li, Y, Serra, SA, Zhang, Y, Yankaskas, CL, He, S, Valverde, MA, et al
Science advances. 2019;(7):eaaw7243
Abstract
How cells sense hydraulic pressure and make directional choices in confinement remains elusive. Using trifurcating Ψ-like microchannels of different hydraulic resistances and cross-sectional areas, we discovered that the TRPM7 ion channel is the critical mechanosensor, which directs decision-making of blebbing cells toward channels of lower hydraulic resistance irrespective of their cross-sectional areas. Hydraulic pressure-mediated TRPM7 activation triggers calcium influx and supports a thicker cortical actin meshwork containing an elevated density of myosin-IIA. Cortical actomyosin shields cells against external forces and preferentially directs cell entrance in low resistance channels. Inhibition of TRPM7 function or actomyosin contractility renders cells unable to sense different resistances and alters the decision-making pattern to cross-sectional area-based partition. Cell distribution in microchannels is captured by a mathematical model based on the maximum entropy principle using cortical actin as a key variable. This study demonstrates the unique role of TRPM7 in controlling decision-making and navigating migration in complex microenvironments.
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Synthesis and evaluation of a novel water-soluble high Se-enriched Astragalus polysaccharide nanoparticles.
Meng, Y, Zhang, Y, Jia, N, Qiao, H, Zhu, M, Meng, Q, Lu, Q, Zu, Y
International journal of biological macromolecules. 2018;(Pt B):1438-1448
Abstract
Selenium is an essential trace element in human body. Se-deficiency is common phenomenon in all over the world, which severely harms the health of organism and causes the etiology of many chronic, degenerative diseases, such as atherosclerosis, arthritis, cancers, hypoimmunity, hypothyroidism and viral diseases. So, the research on preparation of Se-supplementing with the effective, safe and high Se content was imperative. In this study, Se-enriched Astragalus polysaccharide nanoparticles (Se-APS) were prepared by the previous optimization experimental conditions, as follows: reaction temperature 80.5 °C, pH 7.8, ratio of catalyst to APS 0.57:1.0 g·g-1, and reaction time 62 min. The Se content of Se-APS was as high as 13.42 ± 0.37%, characterized by energy spectrometer, thermogravimetry, X-ray diffraction, fourier transform infrared, particle size, zeta potential and atomic force. Se release of the Se-APS in vitro followed the Higuchi's kinetics model and exhibited the basically same release pattern in artificial gastric juice (pH 2.0), artificial intestinal juice (pH 8.0) and PBS (pH 7.4). The proliferation of T-lymphocytes with Se-APS incubation increased at an average of 13.87%, comparing with APS. It could not only enhance the proliferation of T-lymphocytes, but also effectively suppress malignant proliferation of HepG2 cells and reduce cell migration and invasion. We prepared a novel water-soluble Se-APS by using a chelating method, which was promising as a novel Se supplements with high Se content and good bioactivity.
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Increased salt consumption induces body water conservation and decreases fluid intake.
Rakova, N, Kitada, K, Lerchl, K, Dahlmann, A, Birukov, A, Daub, S, Kopp, C, Pedchenko, T, Zhang, Y, Beck, L, et al
The Journal of clinical investigation. 2017;(5):1932-1943
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Abstract
BACKGROUND The idea that increasing salt intake increases drinking and urine volume is widely accepted. We tested the hypothesis that an increase in salt intake of 6 g/d would change fluid balance in men living under ultra-long-term controlled conditions. METHODS Over the course of 2 separate space flight simulation studies of 105 and 205 days' duration, we exposed 10 healthy men to 3 salt intake levels (12, 9, or 6 g/d). All other nutrients were maintained constant. We studied the effect of salt-driven changes in mineralocorticoid and glucocorticoid urinary excretion on day-to-day osmolyte and water balance. RESULTS A 6-g/d increase in salt intake increased urine osmolyte excretion, but reduced free-water clearance, indicating endogenous free water accrual by urine concentration. The resulting endogenous water surplus reduced fluid intake at the 12-g/d salt intake level. Across all 3 levels of salt intake, half-weekly and weekly rhythmical mineralocorticoid release promoted free water reabsorption via the renal concentration mechanism. Mineralocorticoid-coupled increases in free water reabsorption were counterbalanced by rhythmical glucocorticoid release, with excretion of endogenous osmolyte and water surplus by relative urine dilution. A 6-g/d increase in salt intake decreased the level of rhythmical mineralocorticoid release and elevated rhythmical glucocorticoid release. The projected effect of salt-driven hormone rhythm modulation corresponded well with the measured decrease in water intake and an increase in urine volume with surplus osmolyte excretion. CONCLUSION Humans regulate osmolyte and water balance by rhythmical mineralocorticoid and glucocorticoid release, endogenous accrual of surplus body water, and precise surplus excretion. FUNDING Federal Ministry for Economics and Technology/DLR; the Interdisciplinary Centre for Clinical Research; the NIH; the American Heart Association (AHA); the Renal Research Institute; and the TOYOBO Biotechnology Foundation. Food products were donated by APETITO, Coppenrath und Wiese, ENERVIT, HIPP, Katadyn, Kellogg, Molda, and Unilever.
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QSAR models for predicting octanol/water and organic carbon/water partition coefficients of polychlorinated biphenyls.
Yu, S, Gao, S, Gan, Y, Zhang, Y, Ruan, X, Wang, Y, Yang, L, Shi, J
SAR and QSAR in environmental research. 2016;(4):249-63
Abstract
Quantitative structure-property relationship modelling can be a valuable alternative method to replace or reduce experimental testing. In particular, some endpoints such as octanol-water (KOW) and organic carbon-water (KOC) partition coefficients of polychlorinated biphenyls (PCBs) are easier to predict and various models have been already developed. In this paper, two different methods, which are multiple linear regression based on the descriptors generated using Dragon software and hologram quantitative structure-activity relationships, were employed to predict suspended particulate matter (SPM) derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of 209 PCBs. The predictive ability of the derived models was validated using a test set. The performances of all these models were compared with EPI Suite™ software. The results indicated that the proposed models were robust and satisfactory, and could provide feasible and promising tools for the rapid assessment of the SPM derived log KOC and generator column, shake flask and slow stirring method derived log KOW values of PCBs.
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[[Preparation of boronate affinity sorbent and its extraction performance for benzoylurea pesticides]].
Zhang, Y, Mei, M, Liu, Y, Yu, J, Huang, X, Yuan, D
Se pu = Chinese journal of chromatography. 2014;(9):981-7
Abstract
A new boronate affinity monolithic material was prepared and used as the extraction medium of stir cake sorptive extraction (SCSE). The porous boronate affinity sorbent was prepared by in situ copolymerization of 3-acrylamidophenylboronic acid (APB) and divinyl benzene (DVB). To achieve optimum extraction performance for benzoylurea pesticides, several parameters, including desorption solvent, pH value, ionic strength in sample matrix, extraction and desorption times, were investigated in detail. At the same time, a simple, sensitive and environment friendly method for the determination of benzoylurea pesticides in water and juice samples was developed by the combination of SCSE-APBDVB with HPLC equipped with a diode array detector. Under the optimized experimental conditions, the limits of detection (S/N = 3) for target analytes were 0.055-0.11 μg/L in water and 0.095-0.31 μg/L in juice. The precision of the proposed method was evaluated in terms of intra- and inter-assay repeatability calculated as RSD, and it was found that the RSDs were all below 9.0%. The developed method was successfully applied to the determination of benzoylurea pesticide residues in water and juice samples and satisfactory recoveries of spiked target compounds were in the range of 75.6%-109%. The results well demonstrate that the new sorbent can extract benzoylurea pesticides effectively through multi-interactions including boron-nitrogen coordination, hydrogen-bond and hydrophobic interactions between sorbent and analytes.
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A fluid-saturated poroelastic model of the vocal folds with hydrated tissue.
Tao, C, Jiang, JJ, Zhang, Y
Journal of biomechanics. 2009;(6):774-80
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Abstract
The purpose of this study is to develop a continuous model to describe the vibration of the vocal fold with hydrated tissue. This model is unique because it is based on the fluid-saturated porous solid theory. Therefore, this new model can be used to study some vocal fold characteristics that would be difficult to predict using previous models. Numerical simulations show that this model can generate self-oscillation and that its phonation threshold pressure (PTP) is 0.555 kPa. The basic outputs of this model, including fundamental frequency, maximum lateral displacement, surface dynamics, and empirical eigenfunctions, agree with previous models and experimental studies, which validates this new model. The ability to simulate the flow of liquid through the tissue is one of the important advantages of this new model. It was found that the liquid in the vocal fold tissue could be accumulated at the anterior-posterior midpoint during phonation, which could cause a pressure increase in the liquid. The liquid pressure increased from 0.033 to 0.150 kPa when the subglottal pressure increased from 0.555 kPa (PTP) to 0.7 kPa. It was believed that the liquid dynamics in the tissue during phonation could be related to the development of some vocal diseases, such as vocal nodules, edema, and so on. Therefore, we expect that this model might not only provide a more appropriate description of the vocal fold vibration, but that it could also have clinical value in investigating certain vocal fold diseases.
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Gel formation and low-temperature intramolecular conformation transition of a triple-helical polysaccharide lentinan in water.
Zhang, Y, Xu, X, Zhang, L
Biopolymers. 2008;(10):852-61
Abstract
The gelation behavior of the triple-helical polysaccharide lentinan fractions having different molecular weights in water at 25 degrees C were studied by using a rheometer. The analysis of concentration and molecular weight dependence of shear stress and shear viscosity showed that aqueous lentinan is a typical shear-thinning fluid, possessing potential as a viscosity control agent, and that a weak gel with entangled network structure formed. The dynamic oscillatory behavior of lentinan in the temperature range of 1-15 degrees C was also investigated by rheologic method. The storage modulus G' and complex viscosity eta* increased first with decreasing temperature, and underwent a maximum centered at 7-9 degrees C, and then decreased with further decreasing temperature. This abnormal phenomenon was ascribed to formation of rigid structure in the gel state, which was confirmed by the experimental results from micro-DSC. The micro-DSC curves showed that an endothermic peak appeared at 7-9 degrees C for lentinan in water upon heating, which was attributable to the intramolecular order-disorder structure transition similar to triple-helical polysaccharide schizophyllan. Namely, at lower temperature, the side glucose residues of lentinan (triplix II) formed a well-organized triple-helical structure (triplix I) through hydrogen-bonding with the surrounding water molecules. Moreover, this conformation transition was proved to be thermally reversible.