Search results for "PERMEABILITY"
showing 10 items of 596 documents
Cell inactivation and membrane damage after long-term treatments at sub-zero temperature in the supercooled and frozen states.
2008
The survival of cells subjected to cooling at sub-zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze-thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of cells subjected to cold stress, through long-term supercooling experiments, versus freeze-thawing stress. The viability of Escherichia coli, Saccharomyces cerevisiae, and leukemia cells were assessed over time. Supercooled conditions were maintained for 71 days at -10 degrees C, and for 4 h at -15 degrees C, and -20 degrees C, without additives or…
Effect of cyclic loading on fracture strength and microleakage of a quartz fiber dowel with different adhesive, cement and resin core material combin…
2010
Background: This study evaluated the performance of different adhesive-cement-core combinations coupled with quartz fiber dowels after cyclic loading and fracture strength tests and assessed the microleakage using dye penetration method. Methods: Forty maxillary canines (n=10 per group) were restored with fiber dowels (Quartz fiber DT Light Post) and four adhesive-cement-core material combinations [(Group 1: All-Bond 2+C&B (root) / All-Bond 2+Biscore (core); Group 2: All-Bond 2+Bisfil 2B (root) / All-Bond 2+Bisfil 2B (core); Group 3: Scotchbond 1+RelyX ARC (root) / Scotchbond 1+Supreme (core); Group 4: RelyX Unicem (root) / Scotchbond 1+Filtek Supreme (core)]. The specimens were initially c…
Permeability changes of integrin-containing multivesicular structures triggered by picornavirus entry.
2014
Cellular uptake of clustered α2β1-integrin induces the formation of membrane compartments that subsequently mature into a multivesicular body (MVB). Enhanced internalization mediated by clustered integrins was observed upon infection by the picornavirus echovirus 1 (EVI). We elucidated the structural features of virus-induced MVBs (vMVBs) in comparison to antibody-induced control MVBs (mock infection) by means of high-pressure cryo fixation of cells followed by immuno electron tomography during early entry of the virus. Three-dimensional tomograms revealed a marked increase in the size and complexity of these vMVBs and the intraluminal vesicles (ILVs) at 2 and 3.5 hours post infection (p.i.…
Intracellular pH-dependent efflux of the fluorescent probe pyranine in the yeast Yarrowia lipolytica.
2001
International audience; 8-Hydroxypyrene-1,3,6-trisulfonic acid (pyranine) can be used as a vital intracellular pH (pH(i)) indicator. In the yeast Yarrowia lipolytica, a partial efflux of the probe was detected by using the pH-independent wavelength of 415 nm. A simplified correction of the fluorescent signals was applied, enabling to show for this species a good near-neutral pH(i) maintenance capacity in a pH 3.9 medium. Octanoic acid, which is known to have toxic effects on yeast, decreased the pH(i) and increased the 260-nm-absorbing compounds leakage. However, this acid inhibited the fluorescent probe efflux linearly with its concentration suggesting a pH(i)-dependent efflux of pyranine …
T-T cell interactions during in vitro cytotoxic T lymphocyte responses. III. Antigen-specific T helper cells release nonspecific mediator(s) able to …
1980
T helper cell induction and the specificity of T cell-mediated help as generated during alloreactive and H-2-restricted, virus- or hapten-specific cytotoxic T lymphocyte (CTL) responses have been compared. With the use of a double-chamber culture system, it was possible to dissect and separately analyze the induction phase of T helper cells from the T helper cell effector function. The data obtained revealed that during alloreactive as well as H-2-restricted T cell responses, antigen-specific T helper cells are induced. Upon specific restimulation of T helper cells, helper cell function is mediated across a cell-impermeable membrane via soluble products in an apparently nonspecific and nonr…
An improved protocol for electroporation ofOenococcus oeniATCC BAA-1163 using ethanol as immediate membrane fluidizing agent
2008
Aims: To finalize an effective and reproducible electroporation procedure to transform Oenococcus oeni ATCC BAA-1163 strain. Methods and Results: The vector pGID052 was selected to optimize the electroporation procedure. Transformation efficiency was 5·8 × 103 per μg of DNA. Transformation was improved when competent cells were prepared with exponential phase cultures; optimum electroporation parameters were an electric pulse of 12·5 kV cm−1, under a resistance of 200 Ω and the presence of 10% (v/v) ethanol in the electroporation buffer (EPB). Conclusions: An effective protocol to transform O. oeni ATCC BAA-1163 strain by electroporation has been obtained by addition of ethanol to the EP…
The glycosyltransferase activities of lysyl hydroxylase 3 (LH3) in the extracellular space are important for cell growth and viability.
2008
Abstract Lysyl hydroxylase (LH) isoform 3 is a post-translational enzyme possessing LH, collagen galactosyltransferase (GT) and glucosyltransferase (GGT) activities. We have demonstrated that LH3 is found not only intracellularly, but also on the cell surface and in the extracellular space, suggesting additional functions for LH3. Here we show that the targeted disruption of LH3 by siRNA causes a marked reduction of both glycosyltransferase activities, and the overexpression of LH3 in HT-1080 cells increases hydroxylation of lysyl residues and the subsequent galactosylation and glucosylation of hydroxylysyl residues. These data confirm the multi-functionality of LH3 in cells. Furthermore, t…
Hydroxypropylmethylcellulose films for the ophthalmic delivery of diclofenac sodium
2012
Abstract Objectives The aim of this study was to prepare diclofenac/hydroxypropylmethylcellulose (HPMC) and diclofenac-loaded nanoparticles/HPMC films as potential systems for ocular delivery. Methods Two different concentration of the polymer were used: 1.5 and 2.0% w/v. Chitosan–hyaluronic acid nanoparticles were prepared by the ionotropic gelation technique. Nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, drug encapsulation efficiency and rheological studies. In-vitro drug studies and corneal penetration release studies were carried out. Drug release mechanism was finally evaluated by fitting the Ritger and Peppas equation to data. In addit…
Adipokines and Endotoxemia Correlate with Hepatic Steatosis in Non-Alcoholic Fatty Liver Disease (NAFLD)
2020
(1) Background: The etiology of non-alcoholic fatty liver disease (NAFLD) is multifactorial. Dietary composition has been implicated as a factor modulating intestinal barrier and could affect disease severity. The aim of this study was to evaluate dietary intake and markers of intestinal permeability in patients with NAFLD. (2) Methods: We enrolled 63 patients with NAFLD and compared them to age-matched controls. (3) Results: body mass index (BMI) and leptin to adiponectin ratio&mdash
Vibrio cholerae cytolysin: assembly and membrane insertion of the oligomeric pore are tightly linked and are not detectably restricted by membrane fl…
2000
AbstractHemolytic strains of Vibrio cholerae secrete a cytolysin that, upon binding as a monomer, forms pentameric pores in animal cell membranes. Pore formation is inhibited at low temperature and in the absence of cholesterol. We here posed the following questions: firstly, can oligomerization be observed in the absence of pore formation? Secondly, is membrane fluidity responsible for the effect of temperature or of cholesterol upon pore formation? The first issue was approached by chemical cross-linking, by electrophoretic heteromer analysis, and by electron microscopy. None of these methods yielded any evidence of a non-lytic pre-pore oligomer. The second question was addressed by the u…