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Biomedical subjects

G Bartosz

Publications and source records attributed to G Bartosz.

At least 19 recordsLinked to original sources
PubMed1992

Low- and high-Km transport of dinitrophenyl glutathione in inside out vesicles from human erythrocytes.

Kinetic studies on the low- and high-Km transport systems for S-2,4-dinitrophenyl glutathione (DNP-SG) present in erythrocyte membranes were performed using inside-out plasma membrane vesicles. The high-affinity system showed a Km of 3.9 microM a Vmax of 6.3 nmol/mg protein per h, and the low-affinity system a Km of 1.6 mM and a Vmax of 131 nmol/mg protein per h. Both uptake components were inhibited by fluoride, vanadate, p-chloromercuribenzoate (pCMB) and bis(4-nitrophenyl)dithio-3,3'-dicarboxylate (DTNB). The low-Km uptake process was less sensitive to the inhibitory action of DTNB as compared to the high-Km process. N-Ethylmaleimide (1 mM) inhibited the high-Km process only. The high-affinity uptake of DNP-SG was competitively inhibited by GSSG (Ki = 88 microM). Vice versa, DNP-SG inhibited competitively the low-Km component of GSSG uptake (Ki = 3.3 microM). The high-Km DNP-SG uptake system was not inhibited by GSSG. The existence of a common high-affinity transporter for DNP-SG and GSSG in erythrocytes is suggested.

Biological Transport↗
PubMed1992

Irradiation increases proteolysis in erythrocyte ghosts: a spin label study.

X- and gamma-irradiation of human erythrocyte membranes (250-1000 Gy) was found to decrease the ratio of weakly to strongly immobilized signal height of membrane-bound maleimide spin label (Mal-6). Subsequent incubation of spin-labeled membranes at ambient temperature (21 degrees C) induced a progressive increase in this ratio, faster for membranes irradiated with low doses which was hampered by protease inhibitors. These results demonstrate that ionizing radiation stimulates proteolysis of erythrocyte membrane proteins by membrane-associated proteases.

Blood Proteins↗
PubMed1991

Scanning tunneling microscopy of human erythrocyte membranes.

Images of surfaces of human erythrocyte ghosts, lecithin liposomes, spectrin, erythrocyte membrane skeleton, concanavalin A and concanavalin A--decorated erythrocyte ghosts were obtained by scanning tunneling microscopy. The dimensions and surface topography of some membrane structures are described and discussed.

Concanavalin A↗
PubMed1991

Decreased oxidant-induced proteolysis in erythrocytes with enhanced antioxidative defence enzymes due to Down's syndrome.

Erythrocytes of Down syndrome patients, having increased activity of superoxide dismutase and glutathione peroxidase, showed a similar increase in intracellular proteolysis upon stimulation with 1 mmol/l phenylhydrazine than normal erythrocytes. There were no differences in the magnitude of Heinz body formation following the treatment or in the proteolysis of exogenous oxidized substrate. These results demonstrate a protective role for endogenous antioxidative enzymes in the protein damage by oxidative stress which triggers intracellular proteolysis.

Adult↗
PubMed1991

Consequences of the presence of elongated variant of the major transmembrane protein (Band 3 protein) in the human erythrocyte.

Among 56 persons studied, 6 were heterozygous with respect to the elongated variant of the Band 3 protein (anion transporting protein) of the erythrocyte membranes. Erythrocytes containing the variant Band 3 protein did not exhibit morphologic abnormalities, alterations in electron spin resonance spectra of maleimide-spin labeled membranes. In the rate of membrane 'self-digestion' or in chloride permeability. They did however show an increased membrane binding of hemoglobin and aldolase.

Anion Exchange Protein 1, Erythrocyte↗
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↗