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Content available remote Synthesis of carotenoid-cysteine conjugates
Isozeaxanthin under acidic conditions forms an allylic cation which reacts readily with thiol nucleophiles. With N-acetylcysteine as a nucleophile the products obtained are carotenoid-cysteine conjugates in which the amino acid moiety is attached to the carotenoid via sulphur in position 4. The water solubility of the products can be increased by deprotection of the amino group. The antioxidant activity of the products were examined on human liver cells under conditions of hydrogen-peroxide induced oxidative stress.
The mechanical link coupling cytoskeletal and contractile proteins to the sarcolemma of smooth muscle cells is essential for transmitting tension from the cell's interior to exterior. In addition to the well-characterized actin-integrin associations present in adhaerens junctions, our recent work has postulated the existence of a reversible annexin-dependent membrane-cytoskeleton complex, forged in response to a rise in intracellular Ca2+ concentration following smooth muscle cell stimulation (Babiychuk et al., J. Biol Chem. 1999, 274, 35191-35195). Detailed biochemical characterization of the interactions responsible for the formation of this complex revealed that annexins II and VI interact with actomyosin, or detergent-insoluble glycosphingolipid-enriched membrane domains (rafts) purified from smooth muscle, in a concentration- and Ca2+-dependent manner. Annexin II interacted with lipid rafts with high Ca2+-sensitivity, while for annexin VI this interaction required non-physiologically high concentrations of free Ca2+. However, the Ca2+-sensitivity of the latter interaction strongly increased in the presence of purified smooth muscle actomyosin. The detailed biochemical analysis of the interactions occurring between annexin II, annexin VI, actomyosin and rafts suggests that annexins regulate sarcolemmal organization during smooth muscle cell contraction.
Effectiveness of green tea (compared to two single polyphenols) in removing ozone derived reactive oxygen species acting on dioleoylphosphatidylcholine monolayers was determined. Lipid oxidation was followed by changes in mechanical properties of the layer spread on the aqueous subphase containing various amounts of ozone in the presence and absence of polyphenolics. It was shown that the tea extract (containing 8.5 x 10-4 mg/cm3 polyphenols) is capable of inactivating 0.4 ppm ozone. The DPPH radical scavenging test set polyphenols in the order of increasing activity, consistent with their protective effect in relation to lipid oxidation, showing the highest efficacy of EGCG.
Influence of melittin on viability and integrity of cell membrane on grade IV glioma. The grade IV glioma is one of the malignant human tumours. Today there is no effective treatment for this type of cancer. Alternative methods are sought-after in glioma treatment, and lately melittin has been found to be useful in anticancer therapy. The aim of the study was to investigate the effect of melittin on the viability and the integrity of cell membranes of the grade IV glioma cells. The U87 glioma line cells were treated of melittin in increasing concentrations (5, 10, 15, 20 and 50 µg/mL) and incubated for 24 hours. After incubation, the tests were performed in order to investigate the cell morphology, cell viability, membrane integrity and the way of cell death. The results have shown the devastating effect of melittin on the glioma cells. The melittin causes disintegration of cell membranes and induces cell death by apoptosis and less by necrosis.
Wpływ melityny na żywotność i integralność błon komórkowych glejaka IV stopnia. Glejak IV stopnia jest jednym ze złośliwych nowotworów ludzkich. Do dziś nie wynaleziono skutecznego leku do walki z tym nowotworem. Melityna to jeden ze składników jadu pszczelego, który wykazuje działania antyrakowe. Celem badań było zbadanie wpływu melityny na żywotność i integralność błon komórkowych glejaka IV stopnia linii U87. Komórki glejaka IV stopnia linii U87 były traktowane roztworami melityny we wzrastającym stężeniu (5, 10, 15, 20 and 50 µg/mL) i inkubowane przed 24 godziny. Po inkubacji przeprowadzono badania w celu sprawdzenia morfologii komórek, ich żywotności, integralności błon komórkowych oraz drogę śmierci komórkowej. Wyniki wskazują na niszczący wpływ melityny na komórki glejaka. Melityna powoduje dezintegrację błon komórkowych oraz indukuje śmierć komórkową na drodze apoptozy oraz, w mniejszym stopniu, nekrozy.
A simple theoretical model considering cell membrane mechanosensitivity can accurately describe published experimental data on membrane area creeping and recovery, and on osmotic expansion and rupture. The model to data fit reveals real values of membrane tension and elasticity modulus, and the parameters describing membrane organization and kinetics of mechanosensitive membrane traffic, including small solute transport, water permeability, endocytosis, exocytosis, and caveolae formation. This estimation allows for separation and quantitative analysis of the participation of different processes constituting the response of plasmalemma to short time-scale membrane load. The predicted properties of the model were verified for membrane stretching at different osmotic pressures. Finally, a simple hypothesis concerning stressed cell membrane breakdown is postulated.
The aim of the study was to evaluate the resistance of caraway genotypes to water deficit based on the estimation of cell membrane stability (CMS) in leaves using polyethylene glycol (PEG) test. In 2007 and 2008, 25 selected caraway genotypes, originating from European botanical gardens (18), cultivars (2) and our own breeding strains (5), were tested. The plant material was collected from the experimental field. The obtained results showed highly significant differences in cell membrane injuries (p = 0.001) among investigated genotypes. The rank of genotypes in membrane injury index in 2007 was similar to that of 2008. Caraway genotypes originating from Warsaw (49.4%), Cracow (45.3%), Reykiavik (39.9%), Berlin (23.8%), Wisley (22.7%) and strains 9/2 (23.7%), 60/8 (22.2%) exhibited a high level of injury, which showed weak CMS and their high sensitivity to drought. The lowest extent of membrane injury was observed in genotypes originating from Bayreuth (4.2%), Ulm (4.4%), Cluj (5.5%), Lousanne (6.8%) and cultivar "Kończewicki" VI/4 (6.2%), which proves low sensitivity of these genotypes to water deficit and cell membrane stability. These genotypes may be used in further breeding program to improve caraway resistance to drought.
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