Changes in Intracellular Chloride During Osmotic Stress and L-alanine Uptake in Mouse Hepatocytes

A stable intracellular ionic environment is necessary for hepatocytes to function normally. Thus, during hypotonic shock or L-alanine uptake, hepatocytes swell and then exhibit a regulatory volume decrease (RVD), which comprises an increase in K\sp+ conductance (G\sb{\rm K}), an increased K\sp+ efflux, and a hyperpolarization of transmembrane potential (V\sb{\rm m}). Since hepatocyte intracellular Cl\sp- has been demonstrated to distribute passively with V\sb{\rm m}, this study is designed to test the hypothesis that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V\sb{\rm m} might provide an electromotive force for the efflux of hepatocyte intracellular Cl\sp-, which in turn would contribute osmotically to the RVD in hepatocytes. Double-barreled ion-selective microelectrodes were used to measure the changes of hepatocyte transmembrane potential, intracellular ionic activities (especially intracellular Cl\sp- activity, (a\sp{\rm i}\sb{\rm Cl})), and intracellular water volume during either anisotonic stress or L-alanine uptake. Hepatocyte V\sb{\rm m} hyperpolarized, (a\sp{\rm i}\sb{\rm Cl}) decreased, intracellular K\sp+ activity (a\sp{\rm i}\sb{\rm K}) decreased, and intracellular water volume increased during hyposmotic stress. When perfused with L-alanine, hepatocyte V\sb{\rm m} exhibited a transient depolarization followed by repolarization and then underwent a constant hyperpolarization. Meanwhile, hepatocyte intracellular Na\sp+ activity (a\sp{\rm i}\sb{\rm Na}) increased, a\sp{\rm i}\sb{\rm K} & a\sp{\rm i}\sb{\rm Cl} decreased, and intracellular water volume increased. In both hypotonic shock and L-alanine uptake conditions, the decreased a\sp{\rm i}\sb{\rm K} could be attributed to cell swelling. However, the decrease in a\sp{\rm i}\sb{\rm Cl} was greater than could be accounted for by cell swelling. When the change of V\sb{\rm m} was inhibited by K\sp+ channel blockers, the change of a\sp{\rm i}\sb{\rm Cl} was also inhibited. Based on the measured a\sp{\rm i}\sb{\rm Cl}, Cl\sp- was always at its electrochemical equilibrium in all of the control and experimental conditions. The conclusions of this study emphasize the passive distribution of hepatocyte intracellular Cl\sp- with the changes of V\sb{\rm m} induced by hypotonic stress and L-alanine uptake. Thus, the data strongly support the idea that the hypotonic shock- or L-alanine uptake-induced hyperpolarization of V\sb{\rm m} provides electromotive force for the efflux of hepatocyte intracellular Cl\sp-. This could contribute to hepatocyte volume regulation during both hypotonic shock and organic solute transport

A Balancing Domain Decomposition by Constraints Preconditioner for a C\u3csup\u3e0\u3c/sup\u3e Interior Penalty Method

Consider the following weak formulation of a fourth order problem on a bounded polygonal domain Ω in R :

Application of a New Procedure for Power Analysis and Comparison of the Adjusted Univariate and Multivariate Tests in Repeated Measures Designs

A relationship between the multivariate and univariate noncentrality parameters in repeated measures designs was developed for the purpose of assessing the relative power of the univariate and multivariate approaches. An application is provided examining the use of repeated measures designs to evaluate student achievement in a K-12 school syste

Secured green communication scheme for interference alignment based networks

In this paper, a new security and green communication scheme is proposed to the Interference-Alignment (IA) based networks. To achieve a secured communication, full-duplex receivers are utilized to transmit artificial noise (AN). Both the signals and the ANs are used to harvest energy to realize green communication. For these reasons, the feasible conditions of this scheme are analyzed first. Secondly, the average transmission rate, the secrecy performance and the harvested energy are investigated. Thirdly, an optimization scheme of simultaneous wireless information and power transfer (SWIPT) is given to optimize the information transmission and the energy harvesting efficiency. Meanwhile, an improved IA iteration algorithm is designed to eliminate both the AN and the interference. Furthermore, relay cooperation is considered and its system performance is analyzed. The simulations show that the target average transmission rate is not affected by AN, while the secrecy performance can be greatly improved. The energy harvesting efficiency is also better than the traditional schemes. As expected, the average transmission rate further is improved with the relay cooperation

Natural Coevolution of Tumor and Immunoenvironment in Glioblastoma.

Isocitrate dehydrogenase (IDH) wild-type glioblastoma (GBM) has a dismal prognosis. A better understanding of tumor evolution holds the key to developing more effective treatment. Here we study GBM\u27s natural evolutionary trajectory by using rare multifocal samples. We sequenced 61,062 single cells from eight multifocal IDH wild-type primary GBMs and defined a natural evolution signature (NES) of the tumor. We show that the NES significantly associates with the activation of transcription factors that regulate brain development, including MYBL2 and FOSL2. Hypoxia is involved in inducing NES transition potentially via activation of the HIF1A-FOSL2 axis. High-NES tumor cells could recruit and polarize bone marrow-derived macrophages through activation of the FOSL2-ANXA1-FPR1/3 axis. These polarized macrophages can efficiently suppress T-cell activity and accelerate NES transition in tumor cells. Moreover, the polarized macrophages could upregulate CCL2 to induce tumor cell migration. SIGNIFICANCE: GBM progression could be induced by hypoxia via the HIF1A-FOSL2 axis. Tumor-derived ANXA1 is associated with recruitment and polarization of bone marrow-derived macrophages to suppress the immunoenvironment. The polarized macrophages promote tumor cell NES transition and migration. This article is highlighted in the In This Issue feature, p. 2711

Insulin Degrading Enzyme Induces a Conformational Change in Varicella-Zoster Virus gE, and Enhances Virus Infectivity and Stability

Varicella-zoster virus (VZV) glycoprotein E (gE) is essential for virus infectivity and binds to a cellular receptor, insulin-degrading enzyme (IDE), through its unique amino terminal extracellular domain. Previous work has shown IDE plays an important role in VZV infection and virus cell-to-cell spread, which is the sole route for VZV spread in vitro. Here we report that a recombinant soluble IDE (rIDE) enhances VZV infectivity at an early step of infection associated with an increase in virus internalization, and increases cell-to-cell spread. VZV mutants lacking the IDE binding domain of gE were impaired for syncytia formation and membrane fusion. Pre-treatment of cell-free VZV with rIDE markedly enhanced the stability of the virus over a range of conditions. rIDE interacted with gE to elicit a conformational change in gE and rendered it more susceptible to proteolysis. Co-incubation of rIDE with gE modified the size of gE. We propose that the conformational change in gE elicited by IDE enhances infectivity and stability of the virus and leads to increased fusogenicity during VZV infection. The ability of rIDE to enhance infectivity of cell-free VZV over a wide range of incubation times and temperatures suggests that rIDE may be useful for increasing the stability of varicella or zoster vaccines

A Two-Level Additive Schwarz Preconditioner for C\u3csup\u3e0\u3c/sup\u3e Interior Penalty Methods for Cahn-Hilliard Equations

We study a two-level additive Schwarz preconditioner for C0 interior penalty methods for a biharmonic problem with essential and natural boundary conditions with Cahn-Hilliard type. We show that the condition number of the preconditioned system is bounded by C(1 + (H3 / δ3)), where H is the typical diameter of a subdomain, δ measures the overlap among the subdomains, and the positive constant C is independent of the mesh sizes and the number of subdomains. © Springer-Verlag Berlin Heidelberg 2013

Effects of Hyperosmotic Medium on Hepatocyte Volume, Transmembrane Potential and Intracellular K\u3csup\u3e+\u3c/sup\u3e Activity

Hepatocyte transmembrane potential (Vm) behaves as an osmometer and varies with changes in extracellular osmotic pressure created by altering the NaCl concentration in the external medium (Howard, L.D. and Wondergem, R. (1987) J. Membr. Biol. 100, 53). We now have demonstrated similar effects on Vm by increasing external osmolality with added sucrose and not altering ionic strength. We also have demonstrated that hyperosmotic stress-induced depolarization of Vm results from changes in membrane K+ conductance, gK, rather than from changes in the K+ equilibrium potential. Vm and aki of hepatocytes in liver slices were measured by conventional and ion-sensitive microelectrodes, respectively. Cell water vols. were estimated by differences in wet and dry weights of liver slices after 10-min incubations. Effect of hyperosmotic medium on membrane transference number for K+, tk, was measured by effects on Vm of step-changes in external [K+]. Hepatocyte Vm decreased 34, 52 and 54% when tissue was superfused with medium made hyperosmotic with added sucrose (50, 100 and 150 mM). Correspondingly, aKi increased 10, 18 and 29% with this hyperosmotic stress of added sucrose. Tissue water of 2.92 ± 0.10 kg H2O/kg dry weight in control solution decreased to 2.60 ± 0.05, 2.25 ± 0.06 and 2.22 ± 0.05 kg H2O/kg dry weight with additions to medium of 50, 100 and 150 mM sucrose, respectively. Adding 50 mM sucrose to medium decreased tK from 0.20 ± 0.01 to 0.05 ± 0.01. Depolarization by 50% with hyperosmotic stress (100 mM sucrose) also occurred in Cl-free medium where Cl- was substituted with gluconate. We conclude that hepatocytes shrink during hyperosmotic stress, and the aKi increases. The accompanying decrease in Vm is opposite to that expected by an increase in aKi, and at least in part results from a concomitant decrease in gK. Changes in membrane Cl- conductance most likely do not contribute to osmotic stress-induced depolarization, since equivalent decreases in Vm occurred with added sucrose in cells depleted of Cl- by superfusing tissue with Cl-free medium