Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ERYTHROCYTES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1990

Interaction of pentoxifylline with human erythrocytes. I. Interaction of xanthine derivatives with human erythrocyte ghosts.

The interaction of pentoxifylline and other xanthine derivatives with human erythrocyte ghosts was studied. By fluorescence spectroscopy it was found that xanthine derivatives have two modes of binding to erythrocyte ghosts. One is a high-capacity binding to erythrocyte membranes. It seems that the 5-oxohexyl side chain of pentoxifylline is important for this. The second type may be a binding to proteins on the membranes and is specific for pentoxifylline and caffeine. From the circular dichroism spectra, it was presumed that the second binding mode of pentoxifylline occurs at hydrophobic regions of beta-structure of the membrane proteins. The relative high specificity in the interaction of pentoxifylline with erythrocytes should be related to its unique physiological activity on erythrocytes.

Erythrocyte Membrane↗
PubMed1991

Interaction of pentoxifylline with human erythrocytes. III. Comparison of fluidity change of erythrocyte membrane caused by S-adenosyl-L-methionine with that by pentoxifylline.

The change in fluidity by adding pentoxifylline to erythrocyte membranes was compared with that caused by S-adenosyl-L-methionine (SAM) by the method of electron spin resonance (ESR) spectroscopy. When SAM or pentoxifylline was added externally to the erythrocyte suspension (outside), the fluidity of the membrane bilayer was increased after incubation at 37 degrees C. However, the fluidity change in the inner part of the bilayer was relatively small compared to that in its outer part. These fluidity changes were dependent on the incubation time and the temperature. When the erythrocyte suspension was preincubated overnight at 4 degrees C in the presence of drugs (inside), the fluidity of the inner part of the membrane changed significantly. Nevertheless, that of the outer part of the lipid bilayer was not affected. Such an asymmetric fluidity change in the lipid bilayer was not observed by the addition of other xanthine derivatives such as caffeine, theophylline and theobromine. S-Adenosyl-L-homocysteine suppressed and MgCl2 enhanced the increase of the membrane fluidity by SAM or pentoxifylline. Furthermore, the effects of SAM and pentoxifylline on erythrocyte deformability were determined by a filtering technique method. In increasing order the additive effects of SAM and pentoxifylline on the erythrocyte filterability were SAM (outside) less than pentoxifylline (inside) less than pentoxifylline (outside) less than SAM (inside). These results suggest that pentoxifylline also affects the membrane fluidity through the enzymatic methylation of phospholipids.

Erythrocyte Membrane↗
PubMed1979

Sickled erythrocytes, hyphema, and secondary glaucoma: VII. The passage of sickled erythrocytes out of the anterior chamber of the human and monkey eye: light and electron microscopic studies.

Sickled erythrocytes leave the anterior chamber of human and monkey eyes by several mechanisms: intracameral and intratrabecular hemolysis and phagocytosis; entry into and phagocytosis within the iris and ciliary body; and passage into Schlemm's canal. Sickled erythrocytes used as biologic tracers allowed definite confirmation, for the first time in the human, that intracameral erythrocytes can enter Schlemm's canal in the orthograde direction. Erythrocytes appeared to traverse the inner wall of Schlemm's canal through the cytoplasm of individual endothelial cells, rather than between adjacent endothelial cells -- a mechanism similar to that employed by red and white blood cells elsewhere in the body. Although some sickled erythrocytes did pass into Schlemm's canal, considerable obstruction appeared to occur at the corneoscleral meshwork, juxtacanalicular connective tissue, and inner wall of Schlemm's canal, caused largely by the elongated, rigid nature of the sickled cells. Total blockage of Schlemm's canal was not observed.

Anemia, Sickle Cell↗
PubMedDate not supplied

A rosetting test with papain-treated erythrocytes (RBC) for the detection of a minor erythrocyte population (chimerism) with different antigenic expressivity.

A rosetting test with papain-treated erythrocytes was set up and evaluated for the detection of minor erythrocyte populations (chimerism), which can be distinguished by their antigenic differences. The test, for Rh system antigenic differences, has been able to detect erythrocyte populations with a 0.5: 1000 density and a sensitivity 3-4 times as high as that of the antiglobulin test. Critical elements for the optimization of the test are: the final ratio between papain-treated erythrocytes and erythrocytes examined (2:1); the specificity check of the antiserum used which, considering the increased sensitivity, must be performed by the rosetting test itself; the accurate and delicate resuspension of the final pellet. Some disadvantages are the impossibility to detect antigenicity that can be altered by papain and, above all, the scarce possibility of quantifying, if not roughly, the size of the minor population.

Antigens, Surface↗
PubMed1985

[Erythrocyte-associated plasma proteins, a further aspect of erythrocyte function?].

The amount of plasma proteins associated to erythrocytes was determined or calculated by using three different techniques. Thus, there are 3.48 X 10(12) g of protein in a single erythrocyte or 94.12 g of protein respectively in the total of all erythrocytes in a healthy man with a body weight of 70 kg. The mass of plasma protein associated to erythrocytes will decrease in case of immunocomplex aggregates or otherwise denatured plasma proteins being fixed to the erythrocyte surface so that from a purely calculating point of view protein amounts on a scale of up to 46% of all plasma proteins may enter the free blood plasma under extreme conditions. In this, an immediately efficient possibility of compensation is seen by the authors in case of an acute consumption of blood proteins.

Antigen-Antibody Complex↗
PubMed1994

Approach to erythrocyte aggregation through erythrocyte sedimentation rate: application of a statistical model in pathology.

Erythrocyte sedimentation rate (ESR) is mainly used in clinical practice as a screening test for inflammatory diseases and sometimes in the follow-up of patients. However, ESR is highly dependent on erythrocyte aggregation. In this study, using a Sediscan (Becton) automatic device measuring the kinetics of ESR, these results are compared with the measurement of erythrocyte aggregation as determined by laser light backscattering (Erythroaggregometer Affibio). A series of 188 samples from in-patients were tested. Statistical analysis of 13 parameters indicates that 82% of ESR variance may be explained by fibrinogen level, haematocrit and a parameter characterizing erythrocyte aggregation: the aggregation index at 10 s. This correlation was then validated prospectively in 128 other patients and seems to be independent of the underlying disease. Thus ESR in combination with fibrinogen assay and haematocrit may be considered as a simple and economic method to assess erythrocyte aggregation.

Blood Sedimentation↗
PubMed1997

Effects of thymosin alpha-1 on erythrocyte lipid levels and erythrocyte membrane (Na(+)-K+)-ATPase activity in experimental hypercholesterolemia.

Thymosin alpha-1 is an active polypeptide isolated from thymus. This polypeptide is widely used in the diagnosis and treatment of many diseases, especially immune diseases. In this present study, we examined the effects of thymosin alpha-1 on plasma and erythrocyte lipid levels and the changes in erythrocyte membrane (Na+, K+)ATPase activity in hypercholesterolemic rabbits. The erythrocyte lipid levels decreased, whereas the erythrocyte membrane (Na+, K+)ATPase activity increased significantly in these rabbits after thymosin alpha-1 injection. These findings suggest that thymosin alpha-1 is effective on both the lipid level and erythrocyte membrane (Na+, K+)ATPase activity.

Animals↗
PubMed1992

Transport of drugs through human erythrocyte membranes: pH dependence of drug transport through labeled human erythrocytes in the presence of band 3 protein inhibitor.

To reveal the role of the band 3 anion transport protein of the erythrocyte membrane in drug transport through the membrane, the possible effects of inhibitors of anion transport on the permeability of some anionic drugs were examined. The amounts of these drugs that permeated varied markedly with the pH of the outer medium around human erythrocytes that contained the band 3 protein inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS). In the pH range 7.0-8.0, the membrane permeability of drugs through DIDS-treated erythrocytes was affected by a slight pH change (0.2), whereas that through the intact erythrocytes was not pH dependent. These results suggest that the band 3 protein acts not only as a channel for the transport of anions or some anionic drugs but also as protection for the transport system from changes in the pH of the outer medium.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Erythrocyte behavior in free-flow electrophoresis is independent of erythrocyte age.

Enzyme activities (acetylcholinesterase, fluorescein diacetate hydrolase, superoxide dismutase), membrane protein band 4.1a/4.1b ratio and density of various fractions of rabbit erythrocytes separated did not show differences between various fractions of erythrocytes separated by free-flow electrophoresis. Also, electric field deflection of lightest and densest fractions of erythrocytes did not differ. These results point to the lack of changes in surface charge density during in vivo erythrocyte aging.

Acetylcholinesterase↗
PubMed1980

Limits of performance for measurement of blood haemoglobin concentration, number concentration of erythrocytes, and erythrocyte volume fraction in interlaboratory trials. Results of the Finnish proficiency testing programme in haematology.

Limits of performance for measurement of blood haemoglobin concentration, number concentration of erythrocytes, and erythrocyte volume fraction are presented. The limits of performance are based on actual performance by the participants of the Finnish external quality control programme in haematology. In evaluation of a laboratory's performance in measuring blood haemoglobin (Fe) concentration, all values within +/- 0.20 mmol/l of the corrected mean are considered to represent 'good' performance; those between +/- 0.20 and +/-0.40 mmol/l represent 'acceptable' performance and values outside +/- 0.40 mmol/l are 'not acceptable'. Similarly, in measuring number concentration of erythrocytes the limits of +/- 0.2 x 10(12)1(-1) and +/- 0.4 x 10(12)1(-1) and in measuring erythrocyte volume fraction the limits of +/- 0.01 and +/- 0.02 were established. The limits of performance proved to be readily attainable by the survey participants.

Erythrocyte Count↗
PubMed1988

Continuous monitoring of erythrocyte sedimentation process: a new possible mechanism of erythrocyte sedimentation.

An automated system is constructed to record the complete course of erythrocyte sedimentation process. In this system a light source and a paired photodetector are employed to monitor the change of light transmittance at the junction of plasma and the sedimenting red blood cell column, thus providing a continuous record of erythrocyte sedimentation as a function of time. Differentiation of this sedimentation--time curve yields a velocity--time curve of erythrocyte sedimentation. Frequently recorded "spikes" on top of the velocity--time curve imply the episodes of very rapid fall of erythrocytes in the sedimentation tube that cannot be explained by the currently accepted theory of erythrocyte sedimentation based mainly on Stokes' law, and a new mechanism of rouleau coalescing and fracturing is proposed to account for them.

Blood Sedimentation↗
PubMed1998

Plasmodium falciparum: influence of malarial and host erythrocyte skeletal protein interactions on phosphorylation in infected erythrocytes.

Phosphorylation of components of the erythrocyte membrane skeleton has major effects on the physical properties of the membrane. Infection of red cells by the protozoan parasite Plasmodium falciparum leads to a marked increase in the level of phosphorylation of red cell protein 4.1 and the insertion into the red cell skeleton of parasite-encoded phosphoproteins, including the mature-parasite-infected erythrocyte surface antigen (MESA). Because of the tight association of MESA with protein 4.1, we set out to determine the importance of this interaction and that of other parasite-encoded skeletal-associated proteins to phosphorylation of the infected red cell membrane. Our results show that neither MESA nor protein 4.1 is required for phosphorylation of its binding partner. Further, phosphorylation of MESA and protein 4.1 occurs independently of the presence of knobs, the expression of PfHRP1, or cytoadherence phenotype. In contrast to previous studies, we were unable to detect a change in the molecular weight of protein 4.1 in erythrocytes infected with cytoadherent parasite lines. In red cells infected with parasites expressing PfHRP1 (K+), MESA and protein 4.1 are substrates for a kinase with the inhibitor profile of a casein kinase. Surprisingly, however, when we examined phosphorylation of MESA and protein 4.1 in K(-)-infected erythrocytes, we found that casein kinase I and II inhibitors had no, or greatly reduced, effectiveness, and in fact, phosphorylation of these two proteins was enhanced in some instances.

Animals↗
PubMed1990

Effect of phagocytosis of erythrocytes and erythrocyte ghosts on macrophage phagocytic function and hydrogen peroxide production.

Our previous studies have shown that an in vivo phagocytic challenge with IgG-coated erythrocytes can depress Kupffer cell complement and Fc receptor function, as well as decrease the survival rate following endotoxemia and bacteremia. In an effort to better understand the mechanism underlying these in vivo findings, the present study evaluated the in vitro effects of a phagocytic challenge with either IgG-coated erythrocytes (EIgG) or erythrocyte ghosts (GIgG) on macrophage phagocytic and respiratory burst activity. Elicited rat peritoneal macrophage (PM) monolayers were challenged with varying doses of EIgG, then the noninternalized EIgG were lysed hypotonically and the monolayers incubated for an additional hour prior to determining phagocytic function and PMA-stimulated hydrogen peroxide production. Challenge of PM with 1 x 10(6) EIgG per well had no effect, but challenge with 1 x 10(7) or 1 x 10(8) EIgG per well caused a dose-dependent depression of phagocytic function or hydrogen peroxide production. GIgG were formed by hypotonically lysing EIgG bound to PM at 4 degrees C. The bound GIgG were phagocytized during a subsequent incubation at 37 degrees C. Challenge with GIgG depressed phagocytic function only with the highest challenge dose tested (1 x 10(8) per well) and did not depress hydrogen peroxide production. The observation that prior phagocytic challenge with EIgG depressed macrophage function to a greater extent than challenge with GIgG supports our previous in vivo observations. Furthermore, these studies suggest that the internalization of erythrocyte contents, and not phagocytosis per se, plays an important role in determining macrophage host defense function.

Animals↗
PubMed2005

Hemolysis of erythrocytes and erythrocyte membrane fluidity changes by new lysosomotropic compounds.

This work contains the results of studies on the influence of newly synthesized lysosomotropic substances (lysosomotropes) on human erythrocytes. Six homologous series of the compounds differing in the alkyl chain length and counterions were studied. They were found to hemolyse erythrocytes and to change their osmotic resistance. The observed hemolytic effects were dependent both on the compound's structure (polar head dimension and alkyl chain length of compound) and its form (the kind of the counterion). In parallel, the influence of lysosomotropes on fluidity of the erythrocyte membrane was studied. Three different fluorescent probes were used; 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene, p-toluenesulfonate (TMA-DPH) and 6-dodecanoyl-2-dimethylaminonaphthalene (laurdan). Their anisotropy (DPH and TMA-DPH) or general polarization (laurdan) values after incorporation into ghost erythrocyte membranes were measured. The results obtained show that fluidity changes accompanied the effects observed in hemolytic experiments both quantitatively and qualitatively.

Animals↗
PubMed1980

Reactions of the alkylating agent tris(2-chloroethyl)-amine with the erythrocyte membrane. Effects on shape changes of human erythrocytes and ghosts.

The influence of tris(2-chloroethyl)amine on shape changes of human erythrocytes and ghosts was studied in vitro and correlated with alterations in the molecular structure of the membrane. (1) Reaction with 1--2 mM tris(2-chloroethyl)amine, a concentration which caused polymerisation of spectrin as detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis, protected intact erythrocytes against metabolically induced shape changes. (2) When induced by Mg2+-ATP, ghosts porepared from alkylated erythrocytes underwent normal changes in shape. However, when ghosts were treated directly with tris(2-chloroethyl)amine, no Mg2+-ATP-induced shape changes occurred. This fixation in shape appeared to be due to a higher degree of reaction with the alkylating agent. (3) The amount of chlorpromazine necessary for transformation of erythrocytes into stomatocytes was increased for tris(2-chloroethyl)amine-pretreated cells and was dependent on the degree of reaction with tris(2-chloroethyl)amine. (4) Deformability of red cells after reaction with tris(2-chloroethyl)amine was estimated by measuring their rheological behaviour in glass capillary arrays. A slight reduction of the flow rate was observed for cells alkylated with 1--2 mM tris(2-chloroethyl)amine. (5) Extractability of spectrin was diminished and corresponded to the degree of spectrin polymerisation. (6) No difference in the incorporation of 32P by alkylated and untreated cells was found. Sodium dodecyl sulphate polyacrylamide gel electrophoresis and autoradiography of the membrane proteins from 32-P-treated cells showed that the spectrin component 2 and the polymerisation products generated by the reaction with tris(2-chloroethyl)amine were labelled. It is suggested that the observed conservation of cell shape is preferentially caused by the reaction of tris(2-chloroethyl)amine with spectrin.

Alkylating Agents↗
PubMed1984

Aging of the erythrocyte. XIX. Decrease in surface charge density of bovine erythrocytes.

Decrease in electrophoretic mobility of erythrocytes, increase in Km of erythrocyte membrane acetylcholinesterase and decrease in the binding constant of 8-anilino-1-naphthalene sulfonate to erythrocyte membranes demonstrate a decrease in surface charge density of bovine erythrocytes during in vivo aging. This phenomenon seems to be species-specific; it may be due to a diminution of the sialic acid content but may also be contributed by conformational changes of membrane proteins.

Acetylcholinesterase↗
PubMed1977

The effects of ionophores on the fluorescence of the cation 3,3'-dipropyloxadicarbocyanine in the presence of pigeon erythrocytes, erythrocyte 'ghosts' or liposomes.

1. Pigeon erythrocytes, resealed lysed erythrocytes or liposomes derived from erythrocyte lipids were suspended in solutions containing up to 2 micrometer-3,3'-dipropyloxadicarbocyanine iodide. Gramicidin, valinomycin, nigericin or carbonyl cyanide p-trifluoromethoxy-phenylhydrazone, or combinations of these, were used to induce electrical diffusion potentials dependent on Na+, K+ or protons. In each instance hyperpolarization of the cell membrane lowered the fluorescence of the cell suspension, a process that was completed in about 1 min. Subsequent depolarization caused an increase in fluorescence. 2. Quenching of the fluorescence of the cell suspension appeared to be due to the reversible binding of the dye to the cells. Much larger amounts of dye were bound, both to the intact and to the resealed erythrocytes, than would be expected if partitioning of the dye cation followed the Nernst equation. The dependence of the binding on the extracellular dye concentration was studied in the presence and absence of valinomycin. The results were consistent with the suggestion of Sims, Waggoner, Wang & Hoffman [(1974) Biochemistry 13, 3315-3330] that the dye was bound at both membrane surfaces and that, at low dye concentrations, hyperpolarizing the cells promoted dye binding at the inner membrane surface. 3. The applications of the technique are limited by the circumstance that the direct effect of the electric field on the uptake of the dye into the cells is amplified by a binding process that may be affected by other physiological variables.

Animals↗
PubMed2003

Damage to human erythrocytes by radiation-generated HO* radicals: molecular changes in erythrocyte membranes.

The effectiveness of radiation-generated HO* radicals in initiating erythrocyte hemolysis in the presence of oxygen and under anaerobic conditions and prehemolytic structural changes in the plasma-erythrocyte membrane were studied. Under anaerobic conditions the efficacy of HO* radicals in induction of hemolysis was 16-fold lower than under air. In both conditions, hemolysis was the final consequence of changes of the erythrocyte membrane. Preceding hemolysis, the dominating process under anaerobic conditions was the aggregation of membrane proteins. The aggregates were principally formed by -S-S- bridges. A decrease in spectrin and protein of band 3 content suggests their participation in the formation of the aggregates. These processes were accompanied by changes in protein conformation determined by means of 4-maleimido-2,2,6,6-tetramethylpiperidine-N-oxyl (MSL) spin label attached to membrane proteins. Under anaerobic conditions, in the range of prehemolytical doses, the reaction of HO* with lipids caused a slight (10-16%) increase in fluidity of the lipid bilayer in its hydrophobic region with a lack of lipid peroxidation. However, in the presence of oxygen, hemolysis was preceded by intense lipid peroxidation and by profound changes in the conformation of membrane proteins. At the radiation dose that normally initiates hemolysis a slight aggregation of proteins was observed. Changes were not observed in particular protein fractions. It can be suggested the cross-linking induced by HO* radicals under anaerobic conditions and a lack of lipid peroxidation are the cause of a decrease in erythrocyte sensitivity to hemolysis. Contrary, under aerobic conditions, molecular oxygen suppresses cross-linking, catalysing further steps of protein and lipid oxidation, which accelerate hemolysis.

Cell Membrane↗