PubMed Health⌕ Search

Biomedical subjects

W Leyko

Publications and source records attributed to W Leyko.

At least 19 recordsLinked to original sources
PubMed2000

Effect of combined treatment with perindoprilat and low-power red light laser irradiation on human erythrocyte membrane fluidity, membrane potential and acetylcholinesterase activity.

Erythrocyte membrane fluidity, membrane potential and acetylcholinesterase activity were estimated after in vitro combined treatment of human erythrocytes with perindoprilat and low-power red light irradiation. Membrane fluidity was determined using fluorescent labels spectroscopy; membrane potential was evaluated by means of potential-sensitive fluorescent dyes; and acetylcholinesterase activity was estimated using the Ellman method. Both perindoprilat and laser irradiation, when used separately, increase microviscosity in the polar region and hyperpolarize the membranes in comparison with control erythrocytes. The combined action of these agents does not cause any further change in these parameters. Perindoprilat has an additional inhibitory effect on the activity of acetylcholinesterase, whereas laser irradiation causes an increase in the activity of the enzyme. Their combined action restores the initial activity of the enzyme independently of the sequence of treatment with both agents.

Acetylcholinesterase↗
PubMed1999

Interaction of perindoprilat with human red blood cells.

The effects of perindoprilat on the morphology and dynamic properties of human erythrocytes were studied by light microscopy, electron spin resonance spectroscopy and spectrophotometric methods. Erythrocytes were exposed to perindoprilat at 37 degrees C for 30 and 120 min. It was shown that the drug at a concentration of 0.75 microg/ml did not cause significant changes in the structure of erythrocyte membranes. Higher doses of the drug (7.5 and 75 microg/ml) induced changes in membrane fluidity in the hydrophobic core of the lipid bilayer, the conformation of membrane proteins, the number of SH groups and the activity of membrane-bound acetylcholinesterase (AChE). These modifications were accompanied by changes in the shape of erythrocytes and did not depend on time of incubation. Therefore, it is proposed that perindoprilat perturbs the lipid bilayer and disturbs the organization of the protein-lipid environment.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1998

Effect of low-power red light laser irradiation on the viability of human skin fibroblast.

Human skin fibroblast monolayers (S-126 cell line) were exposed to laser radiation (wavelength 670 nm, power density 40 mW/cm2). The energy densities were 2 J/cm2 and 12 J/cm2, respectively, and the irradiation was carried out at a temperature of 22 degrees C. For fibroblast viability evaluation, the colorimetric assay (conversion of thiazolyl blue to formazan) was used. The experiments were carried out at 37 degrees C, in the presence of 5% CO2, and at different time periods of incubation after irradiation (2, 4, 8 h and 1, 2, 3, 4, 5 days). The results indicated that there was a certain stimulating effect on the long-term proliferation of skin fibroblasts and that the stimulation proceeded in two stages, the first one 2 h and the second one 3 days post-irradiation.

Cell Survival↗
PubMed1997

Effect of perindopril therapy on fluidity and potential of erythrocyte membrane from individuals with coronary heart disease.

Erythrocyte membrane fluidity and membrane potential were measured in patients suffering from coronary heart disease (CHD) and treated with perindopril. Membrane fluidity was determined using electron paramagnetic resonance (EPR) spectroscopy, and membrane potential was evaluated using potential-sensitive fluorescent dyes. CHD does not change membrane fluidity at the depth of the 5 carbon in the fatty acid chain of membrane phospholipids. However the hydrophobic core of the membrane is altered in CHD. For 19 CHD patients, the correlation times tau B and tau C of a spin label 16DS were higher than for controls: tau B = (1.84 +/- 0.04) x 10(-9) s and tau C = (2.54 +/- 0.04) x 10(-9) s vs. tau B = (1.62 +/- 0.06) x 10(-9) s; and tau C = (2.24 +/- 0.07) x 10(-9) s (results given as mean +/- SEM). Such results indicate the increased microviscosity in hydrophobic regions of CHD erythrocyte membranes in comparison with controls. Perindopril therapy partly abolished these changes. The membrane potential of CHD red blood cells -17.89 +/- 1.36 mV was higher than the control value -9.83 +/- 0.59 mV. Perindopril treatment shifted the membrane potential value to -13.45 +/- 0.99 mV when measured after a single dose of the drug, or even depolarized the membrane after 7 days of therapy -4.95 +/- 0.73 mV. It is concluded that the erythrocyte membrane is more rigid and hyperpolarized in CHD, and perindopril therapy partly abolishes these changes as early as 3 h after administration.

Adult↗
PubMed1992

Role of membrane components in thermal injury of cells and development of thermotolerance.

Exposure of cells to hyperthermia induces a transient resistance to subsequent heat treatment. The specific mechanisms responsible for hyperthermic cell killing and thermotolerance development are not well understood. It seems that heat may induce at least two different states of thermotolerance, of which one is dependent on protein synthesis. The expression of thermotolerance may include multiple cytoplasmic and membrane components. A number of studies have indicated that membranes play an important role in governing the thermal injury of cells. It seems, therefore, that heat denatured plasma membrane proteins may be a potential target for thermal stress and a trigger for the induction of thermotolerance. The localization of heat shock proteins in the plasma membrane and the suggestion of thermal resistance in enucleate erythrocytes support this suggestion. However, a direct relationship between the plasma membrane and hyperthermic killing or development of thermotolerance has not been found.

Adaptation, Physiological↗
PubMed1991

The response of pig erythrocytes to thermal stress.

The response of the pig erythrocytes exposed either to the action of a single temperature or to two different temperatures was investigated. The cells exposed to single heating indicated an increase of osmotic resistance with increasing temperature. The effect of two different temperatures depended on the time of incubation and the second temperature employed. In a step-up and step-down heating a sensitization to a second heating occurred during the first hours of incubation. We suggest that erythrocytes after prolonged incubation can adapt to thermal stress.

Acclimatization↗
PubMed1991

Effect of hyperthermia and lipid peroxidation on the erythrocyte membrane structure.

The hyperthermic exposure (39-49 degrees C) of human erythrocyte membranes augmented their lipid peroxidation stimulated by 0.1 mM FeCl3 + 1.5 mM ascorbate while having no significant influence on the non-stimulated lipid peroxidation. No effect of hyperthermia and lipid peroxidation on the post-exposure fluidity of the erythrocyte membrane lipids was found by the fluorescence anisotropy of hexatriene and trimethylaminophenylhexatriene, and excimerization efficiency of pyrene. Exposure to iron/ascorbate increased the accessibility of membrane protein tryptophan residues to acrylamide as judged by fluorescence quenching. These results suggest a higher sensitivity of membrane protein organization than of membrane lipid fluidity to the effect of the system inducing lipid peroxidation.

Ascorbic Acid↗
PubMed1988

Ligand and lipid domain stabilization of a membraneous Ca2+-ATPase during hyperthermia.

The susceptibility of the membranous Ca2+-ATPase of sarcoplasmic reticulum to enzymatic inactivation at hyperthermic temperatures was investigated. Inactivation produced a break in the Arrhenius plot at 45-46 degrees C and was accompanied by an increased mobility of spin label, covalently attached to the Ca2+-ATPase. MgADP and MgATP exerted a markedly stabilizing effect on inactivation, both at pH 7.0 and in acidic media. By contrast, high-affinity Ca2+ or Mg2+ binding only moderately stabilized Ca2+-ATPase (inactivation rates were decreased 2-3 times), and this effect was non-additive, i.e., only observed in the absence of the other divalent cation. But withdrawal of K+ and Na+ gave rise to a pronounced destabilization that could be reversed efficiently by high concentrations of Ca2+ or Mg2+. These results are compared with a previous study on detergent solubilized Ca2+-ATPase (Møller, J.V., Lind, K.E. and Andersen, J.P. (1980) J. Biol. Chem. 255, 1912-1920) which showed the enzyme to be markedly stabilized by Ca2+ as well as by nucleotide. It is concluded that, due to the presence of nucleotide, inactivation of Ca2+-ATPase is not likely to occur during malignant hyperthermia and that the native environment of the lipid bilayer provides stabilization of the membrane-embedded and Ca2+-translocating domain of the Ca2+-ATPase.

Animals↗
PubMed1986

Membrane effects of ionizing radiation and hyperthermia.

Results of numerous studies demonstrate that membranes are important sites of cell damage by both ionizing radiation and hyperthermia. Modification of membrane properties (mainly lipid fluidity) affects the cellular responses to radiation and hyperthermia but former concepts that membrane rigidification sensitizes cells to radiation while membrane fluidization potentiates hyperthermic damage have now been seriously challenged. It seems that the effects of membrane fluidity on cell responses to hyperthermia and radiation are due to an indirect influence on functional membrane proteins. The major role of lipid peroxidation in radiation damage to membranes has also been questioned. The existing evidence makes it unlikely that the interaction between radiation and hyperthermia is determined by the action of both agents on the same membrane components.

Animals↗
PubMed1985

A spin label study of the effects of asbestos, quartz, and titanium dioxide dusts on the bovine erythrocyte membrane.

The effects of five UICC asbestos samples, titanium dioxide, and quartz on the bovine red cell membrane have been studied in erythrocyte ghosts by the spin labelling technique. Analysis of the electron paramagnetic resonance (EPR) spectra of two sulphydryl reactive spin labels and one fatty acid spin label in red cell ghosts showed modifications in membrane protein after asbestos treatment but no alterations in membrane lipids. In experiments with quartz no membrane changes were noted but titanium dioxide altered the proteins bound with the protein reactive spin label used in the present study. The possible mechanism for these effects is discussed.

Animals↗
PubMed1984

A spin label study of the effect of chrysotile asbestos on erythrocyte membranes.

Alterations in erythrocyte membranes caused by UICC B chrysotile asbestos fibres were studied in red cell ghosts using the spin label technique. The electron paramagnetic resonance (EPR) spectra of two sulphydryl reactive spin labels and one fatty acid spin probe in erythrocyte ghosts showed membrane protein modifications but no changes in lipid fluidity caused by the haemolytic chrysotile asbestos fibres.

Animals↗
PubMed1983

Effect of insulin on human erythrocyte membrane fluidity in diabetes mellitus.

The effect of insulin in vitro on the fluidity of the human erythrocyte membrane in Type I (insulin-dependent) diabetic patients and healthy control subjects was investigated using a fluorescence technique. It was found that the addition of 10(-9) mol/l porcine insulin significantly increased fluorescent probe lateral mobility in the membrane lipid layer but did not appear to produce any conformational changes of membrane proteins.

Adult↗
PubMed1983

Effect of thiol reagents and ionizing radiation on the permeability of erythrocyte membrane for spin-labeled non-electrolytes.

Four different thiol reagents: p-chloromercuribenzoic acid (pCMB), mercuric chloride (HgCl2), N-ethylmaleimide (NEM), and 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) were employed as agents modifying the transport of a hydrophilic and hydrophobic non-electrolyte spin labels: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) into bovine erythrocytes. Gamma-irradiation of erythrocytes amplified the effects of pCMB, HgCl2 and NEM of inhibition of TEMPOL transport and attenuated them in the case of TEMPO transport. These results suggest that the transport of TEMPOL across the erythrocyte membrane is controlled by both superficially and more deeply located membrane -SH groups while only superficial -SH groups control the transport of TEMPO. The lower extent of inhibition of TEMPO transport indicates a higher contribution of diffusion through the lipid phase to the transport of TEMPO across the erythrocyte membrane as compared with TEMPOL.

Animals↗
PubMed1983

Effect of heparin on the porcine lymphocyte chromatin--II. Comparative study of sedimentation of chromatin DNA and isolated DNA.

1. Sedimentation of chromatin DNA and isolated deproteinized DNA was compared in neutral and alkaline sucrose density gradients after incubation of chromatin or DNA with various concentrations of heparin. 2. Irrespective of the molecular weight of DNA, an increase in the sedimentation constant of DNA was found with increasing concentration of the polyanion employed.

Animals↗
PubMed1983

Effect of gamma radiation on enzymatic activity and sulphydryl groups of human erythrocyte membrane.

The effect of ionizing radiation on human erythrocyte ghost membranes was studied by following changes in membrane -SH groups and activities of four membrane bound enzymes: Na+K+Mg2+ ATP-ase, Mg2+Ca2+ ATP-ase, Na+K+ATP-ase, and AChE. Irradiation up to 100 Gy gamma X-rays produced a significant decrease in the activity of ATP-ase and an increase in AChE activity. At higher radiation doses a marked decrease in the activities of all the enzymes was observed. A correlation between radiation-induced perturbations in enzyme activities and changes in membrane -SH groups was found.

Acetylcholinesterase↗