Search results for "Concentration."
showing 10 items of 1849 documents
Evidence for a selective and electroneutral K+/H+-exchange in Saccharomyces cerevisiae using plasma membrane vesicles
1996
The existence of a K+/H+ transport system in plasma membrane vesicles from Saccharomyces cerevisiae is demonstrated using fluorimetric monitoring of proton fluxes across vesicles (ACMA fluorescence quenching). Plasma membrane vesicles used for this study were obtained by a purification/reconstitution protocol based on differential and discontinuous sucrose gradient centrifugations followed by an octylglucoside dilution/gel filtration procedure. This method produces a high percentage of tightly-sealed inside-out plasma membrane vesicles. In these vesicles, the K+/H+ transport system, which is able to catalyse both K+ influx and efflux, is mainly driven by the K+ transmembrane gradient and ca…
Yeast mRNA cap-binding protein Cbc1/Sto1 is necessary for the rapid reprogramming of translation after hyperosmotic shock.
2011
Global translation is inhibited in Saccharomyces cerevisiae cells under osmotic stress; nonetheless, osmostress-protective proteins are synthesized. We found that translation mediated by the mRNA cap-binding protein Cbc1 is stress-resistant and necessary for the rapid translation of osmostress-protective proteins under osmotic stress.
Effect of L-Histidine on the Survival of a T-Strain of Mycoplasma
1975
The addition of L-histidine to the growth medium prolongs the stationary phase and the survival of a T-strain of mycoplasma. Results of an experiment performed with 14 C-labeled urea demonstrate that the action of L-histidine is based on the retardation of the rise of pH.
Ensemble-based ADME-Tox profiling and virtual screening for the discovery of new inhibitors of the Leishmania mexicana cysteine protease CPB2.8ΔCTE
2018
Abstract: In an effort to identify novel molecular warheads able to inhibit Leishmania mexicana cysteine protease CPB2.8CTE, fused benzo[b]thiophenes and ,'-triketones emerged as covalent inhibitors binding the active site cysteine residue. Enzymatic screening showed a moderate-to-excellent activity (12%-90% inhibition of the target enzyme at 20m). The most promising compounds were selected for further profiling including in vitro cell-based assays and docking studies. Computational data suggest that benzo[b]thiophenes act immediately as non-covalent inhibitors and then as irreversible covalent inhibitors, whereas a reversible covalent mechanism emerged for the 1,3,3'-triketones with a Y-to…
Enzyme-Controlled Nanodevice for Acetylcholine-Triggered Cargo Delivery Based on Janus Au–Mesoporous Silica Nanoparticles
2017
[EN] This work reports a new gated nanodevice for acetylcholine-triggered cargo delivery. We prepared and characterized Janus Au-mesoporous silica nanoparticles functionalized with acetylcholinesterase on the Au face and with supramolecular b-cyclodextrin: benzimidazole inclusion complexes as caps on the mesoporous silica face. The nanodevice is able to selectively deliver the cargo in the presence of acetylcholine via enzyme-mediated acetylcholine hydrolysis, locally lowering the pH and opening the supramolecular gate. Given the key role played by ACh and its relation with Parkinson's disease and other nervous system diseases, we believe that these findings could help design new therapeuti…
Study of the cytotoxic activity of beauvericin and fusaproliferin and bioavailability in vitro on Caco-2 cells.
2010
Abstract Beauvericin (BEA) is a cyclohexadepsipeptide mycotoxin which has insecticidal properties and produces cytotoxic effects in mammalian cells. Fusaproliferin (FUS) is a mycotoxin that has toxic activity against brine shrimp, insect cells, and teratogenic effects on chicken embryos. The aim of this study was to determine the cytotoxicity of BEA and FUS in human epithelial colorectal adenocarcinoma HT-29 and Caco-2 cells, the transepithelial transport and the bioavailability using Caco-2 cells as a simulated in vitro gastrointestinal model of the human intestinal epithelium. The inhibitory concentration (IC 50 ) evidenced by BEA in the Caco-2 cells was 24.6 and 12.7 μM at 24 and 48 h ex…
Synthesis and Antitumor Properties of 2,5-Bis(3'-indolyl) thiophenes: Analogues of Marine Alkaloid Nortopsentin
2007
A series of 11 bis-indolylthiophenes of formula I were obtained by cyclization of bis-indole 1,4-diketones using Lawesson''s reagent. Derivs. I (R = OMe, R1 = SO2Ph), I (R = OMe, R1 = Me), I (R = Cl, R1 = Me), and I (R = OMe, R1 = H) were selected to be evaluated in the full panel of about 60 human tumor cell lines derived from nine human cancer cell types and showed antiproliferative activity generally in the micromolar range. The most sensitive cell lines were: CCRF-CEM, MOLT-4, HL60 (TB), and RPMI-8226 of the leukemia subpanel, HT29 and HCC-2998 cell lines of the colon sub-panel, NCI-H522 of the non-small cell lung cancer sub-panel, LOX IMVI of the melanoma sub-panel, and UO-31 of the re…
Interrelations of the yeast Candida utilis and Cr(VI): metal reduction and its distribution in the cell and medium
2001
Abstract An effect of chromium(VI) ions on the growth and bioaccumulation properties of growing cells of Candida Utilis was studied. Molasses media for yeast growth containing 20 g glucose l −1 and 50+500 mg Cr(VI) l −1 were used in batch cultivation. Addition of 100 mg Cr(VI) l −1 resulted in a threefold decrease in the cell concentration, as compared with the culture grown without metal. Cr(VI) inhibited culture growth in a concentration-dependent manner, this dependence was not linear. Glucose consumption by growing cells depended on the initial Cr(VI) concentration in the medium and correlated with growth activity. No inhibitory effect of high Cr(VI) concentrations on the activity of so…
Presenilin is the molecular target of acidic γ-secretase modulators in living cells.
2012
The intramembrane-cleaving protease γ-secretase catalyzes the last step in the generation of toxic amyloid-β (Aβ) peptides and is a principal therapeutic target in Alzheimer's disease. Both preclinical and clinical studies have demonstrated that inhibition of γ-secretase is associated with prohibitive side effects due to suppression of Notch processing and signaling. Potentially safer are γ-secretase modulators (GSMs), which are small molecules that selectively lower generation of the highly amyloidogenic Aβ42 peptides but spare Notch processing. GSMs with nanomolar potency and favorable pharmacological properties have been described, but the molecular mechanism of GSMs remains uncertain an…
Diffusion in slice preparations bathed in unstirred solutions
1987
A diffusion model is described here, which allows for the estimations of drug concentration changes in porous media, such as in slice tissues of the central nervous system (CNS) bathed in unstirred solutions following abrupt changes of drug concentration. This model may be used for the interpretation of data obtained in neuropharmacological studies if (i) the diffusion coefficient of the molecules under investigation is constant within the excised tissue, (ii) drug molecules are diffusing only in the extracellular space (ECS) and are not bound by the tissue, (iii) drug molecules diffuse mainly within one dimension, (iv) the drug concentration in the bath is changed within 5 s, and (v) the b…