The astrocyte water channel aquaporin-4 (AQP4) is expressed as heterotetramers of M1 and M23 isoforms in which the presence of M23-AQP4 promotes formation of large macromolecular aggregates termed ...orthogonal arrays. Here, we demonstrate that the AQP4 aggregation state determines its subcellular localization and cellular functions. Individually expressed M1-AQP4 was freely mobile in the plasma membrane and could diffuse into rapidly extending lamellipodial regions to support cell migration. In contrast, M23-AQP4 formed large arrays that did not diffuse rapidly enough to enter lamellipodia and instead stably bound adhesion complexes and polarized to astrocyte end-feet in vivo. Co-expressed M1- and M23-AQP4 formed aggregates of variable size that segregated due to diffusional sieving of small, mobile M1-AQP4-enriched arrays into lamellipodia and preferential interaction of large, M23-AQP4-enriched arrays with the extracellular matrix. Our results therefore demonstrate an aggregation state-dependent mechanism for segregation of plasma membrane protein complexes that confers specific functional roles to M1- and M23-AQP4.
All current categorizations of human population, such as ethnicity, ancestry and race, are based on various selections and combinations of complex and dynamic common characteristics, that are mostly ...societal and cultural in nature, perceived by the members within or from outside of the categorized group. During the last decade, a massive amount of a new type of characteristics, that are exclusively genomic in nature, became available that allows us to analyze the inherited whole-genome demographics of extant human, especially in the fields such as human genetics, health sciences and medical practices (e.g., 1,2,3), where such health-related characteristics can be related to whole-genome-based categorization. Here we show the feasibility of deriving such whole-genome-based categorization. We observe that, within the available genomic data at present, (a) the study populations form about 14 genomic groups, each consisting of multiple ethnic groups; and (b), at an individual level, approximately 99.8%, on average, of the whole autosomal-genome contents are identical between any two individuals regardless of their genomic or ethnic groups.
Magnetically actuated soft robots may improve the treatment of disseminated intravascular coagulation. Significant progress has been made in the development of soft robotic systems that steer ...catheters. A more challenging task, however, is the development of systems that steer sub-millimeter-diameter guidewires during intravascular treatments; a novel microrobotic approach is required for steering. In this article, we develop a novel, magnetically actuated, soft microrobotic system, increasing the steerability of a conventional guidewire. The soft microrobot is attached to the tip of the guidewire, and it is magnetically steered by changing the direction and intensity of an external magnetic field. The microrobot is fabricated via replica molding and features a soft body made of polydimethylsiloxane, two permanent magnets, and a microspring. We developed a mathematical model mapping deformation of the soft microrobot using a feed-forward approach toward steering. Then, we used the model to steer a guidewire. The angulation of the microrobot can be controlled from 21.1° to 132.7° by using a magnetic field of an intensity of 15 mT. Steerability was confirmed by two-dimensional
in vitro
tracking. Finally, a guidewire with the soft microrobot was tested by using a three-dimensional (3D) phantom of the coronary artery to verify steerability in 3D space.
ABSTRACT
Airway surface liquid (ASL) volume depletion and mucus accumulation occur in cystic fibrosis (CF). The ASL comprises a superficial mucus layer (ML) overlying a periciliary fluid layer (PCL) ...that contacts surface epithelial cells. We measured viscosity of the ML and PCL from the diffusion of FITC‐dextran dissolved in the ASL of unperturbed, well‐differentiated primary cultures of human bronchial epithelia grown at an air‐liquid interface. Diffusion was measured by fluorescence recovery after photobleaching, using a perfluorocarbon immersion lens and confocal fluorescence detection. Bleaching of an in‐plane 6‐μm‐wide region was done in which diffusion coefficients were computed using solution standards of specified viscosity and finite‐element computations of 2‐layer dye diffusion in 3 dimensions. We found remarkably elevated viscosity in both ML and PCL of CF vs. non‐CF bronchial epithelial cell cultures. Relative viscosities (with saline = 1) were in the range 7–10 in the non‐CF ML and PCL, and 25–30 in both ML and PCL in CF, and greatly reduced by amiloride treatment or mucin washout. These data indicate that the CF airway surface epithelium, even without hyperviscous secretions from submucosal glands, produces an intrinsically hyperviscous PCL and ML, which likely contributes to CF lung disease by impairment of mucociliary clearance. Our results challenge the view that the PCL is a relatively watery, nonviscous fluid layer in contact with a more viscous ML, and offer an explanation for CF lung disease in the gland‐free lower airways.—Derichs, N., Jin, B. ‐J., Song, Y., Finkbeiner, W. E., Verkman, A. S. Hyperviscous airway periciliary and mucous liquid layers in cystic fibrosis measured by confocal fluorescence photobleaching. FASEB J. 25, 2325–2332 (2011). www.fasebj.org
The Korean peninsula is the region of distinctly showing the heavy rain associated with relatively low storm height and small ice water content in the upper part of cloud system (i.e., so-called ...warm-type heavy rainfall). The satellite observations for the warm-type rain over Korea led to a conjecture that the cloud microphysics parameterization suitable for the continental deep convection may not work well for the warm-type heavy rainfall over the Korean peninsula. Therefore, there is a growing need to examine the performance of cloud microphysics schemes for simulating the warm-type heavy rain structures over the Korean peninsula. This study aims to evaluate the capabilities of eight microphysics schemes in the Weather Research and Forecasting (WRF) model how warm-type heavy rain structures can be simulated, in reference to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) reflectivity measurements. The results indicate that the WRF Double Moment 6-class (WDM6) scheme simulated best the vertical structure of warm-type heavy rain by virtue of a reasonable collision-coalescence process between liquid droplets and the smallest amount of snow. Nonetheless the WDM6 scheme appears to have limitations that need to be improved upon for a realistic reflectivity structure, in terms of the reflectivity slope below the melting layer, discontinuity in reflectivity profiles around the melting layer, and overestimation of upper-level reflectivity due to high graupel content.
Potassium (K(+)) ions released into brain extracellular space (ECS) during neuroexcitation are efficiently taken up by astrocytes. Deletion of astrocyte water channel aquaporin-4 (AQP4) in mice ...alters neuroexcitation by reducing ECS K(+) accumulation and slowing K(+) reuptake. These effects could involve AQP4-dependent: (a) K(+) permeability, (b) resting ECS volume, (c) ECS contraction during K(+) reuptake, and (d) diffusion-limited water/K(+) transport coupling. To investigate the role of these mechanisms, we compared experimental data to predictions of a model of K(+) and water uptake into astrocytes after neuronal release of K(+) into the ECS. The model computed the kinetics of ECS K(+) and volume, with input parameters including initial ECS volume, astrocyte K(+) conductance and water permeability, and diffusion in astrocyte cytoplasm. Numerical methods were developed to compute transport and diffusion for a nonstationary astrocyte-ECS interface. The modeling showed that mechanisms b-d, together, can predict experimentally observed impairment in K(+) reuptake from the ECS in AQP4 deficiency, as well as altered K(+) accumulation in the ECS after neuroexcitation, provided that astrocyte water permeability is sufficiently reduced in AQP4 deficiency and that solute diffusion in astrocyte cytoplasm is sufficiently low. The modeling thus provides a potential explanation for AQP4-dependent K(+)/water coupling in the ECS without requiring AQP4-dependent astrocyte K(+) permeability. Our model links the physical and ion/water transport properties of brain cells with the dynamics of neuroexcitation, and supports the conclusion that reduced AQP4-dependent water transport is responsible for defective neuroexcitation in AQP4 deficiency.
New high-throughput assay formats and innovative screening technologies are needed for miniaturized screens using small quantities of near-native, patient-derived cells. Here, we developed a hollow ...micropillar array method to screen compounds using epithelial cells cultured on a porous support, with the goal of screening thousands of compounds using a single 24 mm diameter transwell filter containing cultured cells. Test compounds (∼1 nL) in an alginate hydrogel were printed by microinjection in hollow cylindrical micropillars (height = 150 μm, inner diameter = 100 μm) spaced 300 μm apart in a square array configuration. Compounds were delivered by positioning the array near the surface of a cell layer, with 5–10 μm of distance between the micropillars and cell surface. Micropillar array geometry, and the viscosity of the hydrogel and overlying solutions, were optimized computationally and experimentally to produce sustained exposure of cells to test compounds with minimal cross-talk from compounds in neighboring micropillar wells. The method was implemented using a 10 × 10 micropillar array (size = 3 × 3 mm) on CFTR-expressing epithelial cells, in which CFTR chloride channel function was measured from fluorescence in response to iodide addition using a genetically encoded cytoplasmic yellow fluorescent protein halide indicator. The hollow micropillar array platform developed here should be generally applicable for high-capacity drug screening using small numbers of cells cultured on solid or porous supports.
Rotavirus is the most common cause of severe secretory diarrhoea in infants and young children globally. The rotaviral enterotoxin, NSP4, has been proposed to stimulate calcium-activated chloride ...channels (CaCC) on the apical plasma membrane of intestinal epithelial cells. We previously identified red wine and small molecule CaCC inhibitors.
To investigate the efficacy of a red wine extract and a synthetic small molecule, CaCCinh-A01, in inhibiting intestinal CaCCs and rotaviral diarrhoea.
Inhibition of CaCC-dependent current was measured in T84 cells and mouse ileum. The effectiveness of an orally administered wine extract and CaCCinh-A01 in inhibiting diarrhoea in vivo was determined in a neonatal mouse model of rotaviral infection.
Screening of ∼150 red wines revealed a Cabernet Sauvignon that inhibited CaCC current in T84 cells with IC50 at a ∼1:200 dilution, and higher concentrations producing 100% inhibition. A >1 kdalton wine extract prepared by dialysis, which retained full inhibition activity, blocked CaCC current in T84 cells and mouse intestine. In rotavirus-inoculated mice, oral administration of the wine extract prevented diarrhoea by inhibition of intestinal fluid secretion without affecting rotaviral infection. The wine extract did not inhibit the cystic fibrosis chloride channel (CFTR) in cell cultures, nor did it prevent watery stools in neonatal mice administered cholera toxin, which activates CFTR-dependent fluid secretion. CaCCinh-A01 also inhibited rotaviral diarrhoea.
Our results support a pathogenic role for enterocyte CaCCs in rotaviral diarrhoea and demonstrate the antidiarrhoeal action of CaCC inhibition by an alcohol-free, red wine extract and by a synthetic small molecule.
There is an uncertainty in how the Pacific Walker circulation (PWC) will change in response to increased greenhouse gas (GHG) warming. On average, climate models predict that the PWC will weaken. ...Observational evidence is mixed, with some evidence supporting the models while others do not. In this study, insight into the PWC trend is provided by examining the tropical dry static stability, a quantity that is inversely proportional to the strength of the PWC. For the 1979–2012 period, the static stability increased markedly in all phase 5 of the Coupled Model Intercomparison Project (CMIP5)models, far more so than in the satellite and global reanalysis data, which show a strengthening of the PWC. The stabilization is greater for a subset of models that simulate a significant weakening of the PWC.
With the observed sea surface temperature as the lower boundary condition, over the western tropical Pacific, atmospheric models that belong to the weakening-PWC-CMIP5 group produce greater stabilization than those that belong to the strengthening-PWC-CMIP5 group. Compared with the latter group, the former group of atmospheric models simulates weaker trade winds over the western and central tropical Pacific and, consistent with the Bjerknes mechanism, the corresponding CMIP5 models produce a weaker west–east gradient in tropical SST. Given that the models’ convective parameterizations overstabilize the atmosphere compared with an explicit convection, the findings here suggest that the models’ representations of tropical convection and stability contribute to the models’ tendency to simulate a weakening of the PWC and an El Niño–like SST.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Various pathophysiologic mechanisms leading to sickness behaviors have been proposed. For example, an inflammatory process in the hypothalamus has been implicated, but the signaling modalities that ...involve inflammatory mechanisms and neuronal circuit functions are ill-defined. Here, we show that toll-like receptor 2 (TLR2) activation by intracerebroventricular injection of its ligand, Pam3CSK4, triggered hypothalamic inflammation and activation of arcuate nucleus microglia, resulting in altered input organization and increased activity of proopiomelanocortin (POMC) neurons. These animals developed sickness behavior symptoms, including anorexia, hypoactivity, and hyperthermia. Antagonists of nuclear factor kappa B (NF-κB), cyclooxygenase pathway and melanocortin receptors 3/4 reversed the anorexia and body weight loss induced by TLR2 activation. These results unmask an important role of TLR2 in the development of sickness behaviors via stimulation of hypothalamic microglia to promote POMC neuronal activation in association with hypothalamic inflammation.
PDF
