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Biomedical subjects

G Bartosz

Publications and source records attributed to G Bartosz.

At least 91 records · Page 5Linked to original sources
PubMed1991

Interaction of ethanol and xylene in their effects on erythrocytes and other haematological parameters in the rat.

Rats were given ethanol in drinking water for 8 months, followed by inhalation exposure (5 h daily) to 12,000 mg m-3 xylene for 9 days. Combined exposure to xylene and ethanol induced the same changes in the haematological, biochemical and biophysical parameters of the erythrocyte membrane as those found previously in our experiment with toluene-ethanol. Macrocytosis, a decrease in sedimentation rate and erythrocyte packing difference, as well as decreased fluidity of the erythrocytes membrane in the middle zone of the lipid bilayer, were the most significant changes of exposure to ethanol and xylene.

Animals↗
PubMed1991

Spin label detection and free radical nature of DNA damage by hydralazine.

1. Incubation with hydralazine was shown to induce degradative changes of calf thymus DNA spin-labeled with 3-(2-bromoacetamido)-2,2,5,5-tetramethyl-1-pyrrolidono-1-oxyl and 4-(2-bromoacetamido)-2,2,6,6-tetramethylpiperidino-1-oxyl detectable from electron spin resonance specta. 2. Hydralazine, especially in the presence of Fe2+ induced formation of thiobarbituric acid (TBA)-reactive DNA degradation products. 3. The formation of TBA-reactive products was prevented by catalase, EDTA and scavengers of .OH radicals and enhanced by superoxide dismutase which suggests that .OH radicals formed by the Fenton mechanism mediate the DNA damage by hydralazine-Fe2+.

Catalase↗
PubMed1991

Hydralazine stimulates production of oxygen free radicals in Eagle's medium and cultured fibroblasts.

The effect of hydralazine on the oxygen free radical production was studied in whole cultured murine liver fibroblasts and mitochondrial and microsomal fractions of the cells by ESR spin trapping with DMPO and measurement of Tiron semiquinone formation. Hydralazine itself was found to generate free radicals in phosphate buffer and especially in Eagle's Minimal Essential Medium. Most of the adduct of the spin trap DMPO was due to its reaction with hydralazine-induced hydroxyl radical. Moreover, this compound stimulated free radical formation in fibroblasts. These data suggest that hydralazine alters the cellular free radical metabolism which may have implications for the biological activity of this drug.

Animals↗
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↗
PubMed1991

Erythrocyte aging: physical and chemical membrane changes.

The mammalian erythrocyte is an interesting model for studies of membrane aging. Experimental approaches to this problem involve, first of all, comparison of properties of erythrocytes separated by density because red blood cell age correlates with density in principle. Other approaches to study red cell membrane aging, such as hypertransfusion, are also discussed. A number of physical and chemical changes occur in erythrocytes with aging. Crucial to the elucidation of aging mechanisms is to determine which are primary and which are secondary. Immunoglobulin G binding triggers cellular removal and seems necessary for the recognition of senescent erythrocytes. Cellular deformability decreases while fragility to hemolytic factors generally increases and surface charge density does not alter. Perhaps more important are reactions of reactive oxygen species with membrane constituents and subsequent proteolysis. These are implicated as causative factors in red cell aging, immunoglobulin binding and recognition of senescent erythrocytes.

Animals↗
PubMed1990

Hyperthermia, unlike ionizing radiation and chemical oxidative stress, does not stimulate proteolysis in erythrocytes.

1. Oxidative stress by phenazine methosulfate stimulated proteolysis in erythrocytes. 2. Gamma-irradiation of erythrocytes in the range of 50-1000 Gy also resulted in the induction of proteolysis. 3. Though it has been suggested that hyperthermia imposes an oxidative stress on a cell, hyperthermic exposure of erythrocytes (30 min, 39-49 degrees C) did not stimulate proteolysis during subsequent incubation of whole cells or hemolysates. 4. Proteolytic degradation of spectrin was accelerated during incubation of membranes isolated from cells heated above 45 degrees C but this effect seems to be due rather to thermal denaturation of spectrin than to oxidative modification of cellular proteins by hyperthermia.

Amino Acids↗
PubMed1990

Effect of carminomycin on the viability of fibroblasts from patients with regular trisomy 21.

The sensitivity of three human fibroblast lines, trisomic with respect to chromosome 21, to an anthracycline antibiotic carminomycin was compared with that of a normal fibroblast line using a 51Cr release assay. It was found that for an intermediate antibiotic concentration (10 microM) the sensitivity of trisomic fibroblasts, of increased content of Cu,Zn-superoxide dismutase was lower. These results suggest a role for superoxide-mediated membrane damage in the cytotoxic action of anthracycline antibiotics.

Carubicin↗
PubMed1989

Proteolytic activity of human erythrocyte membrane during ghosts preparation.

1. Proteins in human erythrocyte membranes after red blood cells hemolysis revealed relatively high rate of self-digestion. 2. This indicates hemolysis as a critical moment for membrane proteases activation. 3. The detailed pattern of band 3 protein and spectrin degradation during ghosts preparation was more complicated and reflected both the changes in proteolytic susceptibility and extraction of some proteases. 4. Further extraction of membrane proteins by alkali stripping resulted in an increase in the self-digestion rate and decrease in the degradation rate of an exogenous substrate.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1989

Endogenous proteolysis of the human erythrocyte membrane as studied by two-dimensional gel electrophoresis and electron spin resonance.

1. Endogenous proteolysis in human erythrocyte membranes was studied in human erythrocyte membranes incubated at 37 degrees C by monitoring changes in 2-D electrophoretic pattern of membrane polypeptides and in the spectra of maleimide-spin labeled membranes. 2. A strong effect of exogenous proteases derived from contaminating other blood elements was found, resulting in formation of specific spots on 2-D electropherograms, requiring very careful leukocyte removal in investigations of red cell membrane protein composition and proteolysis. 3. Studies of the effects of protease inhibitors and Ca2+ confirmed a complex pattern of endogenous red cell membrane proteolysis ("self-digestion") involving many substrates and enzymes. 4. A promoting effect of high concentrations (150 mM) of Ca2+ on endogenous red cell membrane proteolysis was found.

Blood Proteins↗
PubMed1989

Membrane self-digestion during erythrocyte storage.

The effect of storage of erythrocytes (in vitro aging) on the self-digestion of erythrocyte membrane proteins was studied by analysis of membrane protein electropherograms. Incubation of bovine erythrocytes in medium 199 for 7 to 31 days resulted in a progressive decrease in the self-digestion rate of band 3 and a less regular decrease in the rate of self-digestion of spectrin. This effect may be explained as a result of a decrease of membrane protease activity and an increase in the proteolytic susceptibility of membrane proteins.

Animals↗
PubMed1989

Cystic fibrosis: II. Altered microviscosity of erythrocyte membrane.

Erythrocyte membrane fluidity alterations in cystic fibrosis are described. The relative flexibility of the membrane was studied using lipid spin label, i.e. methyl-5-doxylpalmitate (M5DP), and pyrene as a fluorescence probe. It was found that there was a decrease of membrane fluidity in the hydrophobic midzone of the membrane, probed by pyrene, as well as at the hydrophilic surface region, probed by M5DP.

Child↗
PubMed1989

Effect of cell age on the quenching of erythrocyte membrane protein fluorescence.

The accessibility of membrane protein tyrosyl and tryptophanyl residues for fluorescence quenchers (acrylamide and iodide) was compared in membranes isolated from various age fractions of bovine erythrocytes. An increase in the quenching efficiency of membrane protein fluorescence was found with advancing erythrocyte age, as demonstrated by elevated values of the Stern-Volmer constant. These results provide evidence for a progressive change in membrane protein organization during erythrocyte aging, enhancing the availability of membrane proteins for interactions with external factors.

Animals↗
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↗