SEARCH · PubMed Health

Results for “ERYTHROCYTES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 415 records · Page 23Linked to original sources

PubMed1992

Erythrocytes as a total barrier for renal excretion of hydrochlorothiazide: slow influx and efflux across erythrocyte membranes.

The potential barrier effect of erythrocytes (RBC) on renal excretion (mainly by tubular secretion) of hydrochlorothiazide (HCTZ) was evaluated in nine anesthetized rats during steady-state iv infusion. Drug concentrations in plasma and blood from the carotid artery and renal vein were assayed by a simple modified HPLC method. Renal extraction ratios were concentration-independent with a mean of 0.17 +/- 0.05 (SD). The renal excretion was found to occur primarily from the drug in plasma; the mean net fractional removal from plasma was 0.57 +/- 0.12, while that from RBC was less than 0.008 +/- 0.041. The virtual total unavailability of HCTZ from RBC (containing approximately 70% of drug in arterial blood) for renal excretion is attributed to relatively slow efflux of drug from RBC to plasma during each passage through the kidney compared with the blood transit time (in seconds). Preliminary in vitro influx and efflux kinetics of HCTZ across RBC membranes were studied using rat and human blood. The flux data could be adequately described by a linear, reversible, closed two-component system model, and the mean equilibration half-times (ET1/2) in rat and human blood were 10.9 and 20.5 min, respectively. The mean residence time of drug in blood circulation of rats was estimated to be 8.32 +/- 1.06 min, which is shorter than the ET1/2. This is consistent with data indicating that distribution equilibrium of HCTZ in arterial blood might not be reached in vivo even at steady state. Other implications of slow transport kinetics of drugs across RBC membranes are discussed.

Adult↗

PubMedDate not supplied

Transmembrane 19F NMR chemical shift difference of fluorinated solutes in liposomes, erythrocytes and erythrocyte ghosts.

In erythrocytes suspended in isotonic medium, a number of fluorinated anions showed well resolved 19F NMR resonances from the solute populations in the intra- and extracellular compartments; the intracellular resonances were shifted to higher frequency (low field). In addition 19F NMR resonances of extracellular solutes were shifted to higher frequency when bovine serum albumin was incorporated into the extracellular medium. The dependence of 19F NMR chemical shift on protein concentration was also demonstrated using resealed red cell ghosts and liposomes; in the presence of external hemoglobin, lysozyme and bovine serum albumin, the shift of the external resonances was to higher frequency. In addition, significant high frequency shifts of 19F NMR resonances were evident along with an increase of temperature. The results of the present study further support the contention that the principal physical basis for the shifts is the disruption of direct hydrogen bonds between 19F of the solutes and (primarily) solvent H2O by protein hydration. The 'split peak' phenomenon is of general importance in biological systems where a transmembrane protein-concentration difference exists.

Blood Proteins↗

PubMed2002

Selective increase of autoimmune epitope expression on aged erythrocytes in mice: implications in anti-erythrocyte autoimmune responses.

We investigated the impact of changes occurring during red blood cell (RBC) ageing on the RBC-binding activity of pathogenic anti-erythrocyte monoclonal antibodies derived from autoimmune-prone New Zealand black (NZB) mice. As assessed by flow cytometric analysis on in vivo biotinylated RBCs, all five NZB-derived anti-RBC mAb exhibited more efficient binding to aged RBCs than to young RBCs, and resulted in a selective elimination of more aged RBCs from the circulating blood. In addition, treatment of RBCs with proteases markedly enhanced the binding of all five anti-RBC mAb, raising the possibility that increased exposure of autoimmune epitopes on aged RBCs may be in part, a result of contacts with proteolytic enzymes during the lifetime of circulating RBCs. In marked contrast, the binding activity of mAb raised in non-autoimmune animals against antigens expressed on RBCs, such as CD44, CD47, CD147 and TER-119, was either decreased or unchanged with RBC ageing, and these epitopes, except for that recognized by anti-CD47 mAb, were highly sensitive to mild treatment with proteases. Our data unravel the unique molecular feature of RBC epitopes involved in autoimmune haemolytic anaemia, suggesting that membrane alterations in aged RBCs might play a significant role in the development of the autoantibody response to RBCs.

Anemia, Hemolytic, Autoimmune↗

PubMed1996

A possible role of adenylate metabolism in human erythrocytes. 2. Adenylate metabolism is able to improve the erythrocyte volume stabilization.

We constructed and studied a mathematical model that describes the control of cell volume, ion balance, energy and adenylate metabolism in human erythrocytes. According to the model, adenylate metabolism can provide an effective stabilization of the cell volume over relatively large changes of cell parameters. For example, the steady-state value of cell volume remains almost unchanged when the cell membrane permeability increases by 15-fold. The cell volume also changes only slightly over large changes in the parameters of energy metabolism. The relaxation time for the cell volume changes is about 100 hr over changes in these parameters. In other words, the volume stabilization operates most effectively against long-term slow perturbations.

Adenosine Monophosphate↗

PubMed1983

Lithium's inhibition of erythrocyte cation countertransport involves a slow process in the erythrocyte.

Chronic administration of lithium (Li+) to human subjects results in reduction of Li+/Na+ countertransport in their erythrocytes (RBC). The time course of development of inhibition is much slower than one would expect for an immediate effect of Li+ on the RBC membrane. Possible explanations include pharmacokinetic delays, a mediating humoral agent, and a slow process in the RBC. To discriminate among these possibilities, we incubated human RBC in sterile culture by the method of Freedman (Freedman, J.C. 1983. J. Membrane Biol. 75:225--231), which permits much longer incubations than other methods. As gauged by eight measures, the incubated RBC remain viable for two weeks. Small changes in intracellular concentrations with time during incubation are in the same direction as the changes associated with natural aging of RBC in vivo, except for a rise in ATP and related cation shifts during the first few days of incubation. Treatment of incubated RBC with 2 mM Li+ inhibits countertransport by 48% without affecting Li+ leak efflux. The inhibition develops slowly: it is half-maximal after 1--2 days and maximal by 4--7 days. Differences between in vivo results and our incubated cells in the time course of inhibition are as expected from the pharmacokinetic delays operating in vivo. The inhibition is reversible on removing Li+. Li+ inhibits countertransport similarly slowly and to a similar degree from inside the RBC and from outside. Hence the slow time course of inhibition in vivo is not due to a humoral factor or to the time required for intracellular Li+ accumulation and is only partly due to pharmacokinetic delays. The delay must involve an unidentified slow process at the level of the RBC.

Biological Transport, Active↗

PubMed1991

Interaction between advancing ice fronts and erythrocytes. Mechanism of erythrocyte destruction upon freezing and influence of cryoprotective agents.

It can be shown theoretically and experimentally that in purely aqueous suspension, cells (as well as microsolutes) are excluded by advancing freezing fronts. This puts the cells under considerable osmotic stress and may be considered to be the major source of cell destruction upon freezing. It is also shown theoretically and experimentally that in aqueous suspensions, admixed with appropriate concentrations of a cryoprotectant (e.g., glycerol), cells are engulfed by advancing freezing fronts: Under such conditions, cells do not undergo any osmotic stress and remain undamaged when frozen. The influence of various common cryoprotectants is discussed, as is the reason why penetrating as well as nonpenetrating agents can be equally effective cryoprotective agents. The reason why leukocytes require lower cryoprotectant concentrations than erythrocytes is also elucidated.

Cell Communication↗

PubMed1988

Elastic properties of the erythrocyte membrane and the critical cell volume of erythrocytes.

The results on elastic membrane area extension during hemolysis, reported by Richieri and Mel (Richieri, G.V. and Mel, H.C. (1985) Biochim. Biophys. Acta 813, 41-50), are discussed. Careful analysis of their data leads to the conclusion, that the differences in osmolarity, as found in the experiment, were insufficient to cause the reported values of elastic changes in erythrocyte volume (17-22%) and of membrane area extension (11-14%). The recalculated values of the elastic extensions of membrane area are not different from those measured by the micropipet method (i.e. 3-4%).

Elasticity↗

PubMed1990

Erythrocyte deformability in diabetes and erythrocyte membrane lipid composition.

Erythrocyte deformability was assessed in 40 diabetic patients, 24 insulin-dependent (IDD) and 16 non-insulin-dependent (NIDD), by measuring the initial filtration flow rate of whole blood, isolated red blood cells (RBC), and isolated RBC membranes with the Hanss hemorheometer, and its relationship to the plasma and ghost membrane lipid composition was investigated. RBC deformability was significantly reduced, whereas the deformability of the isolated RBC membranes did not differ significantly from the controls. In the plasma, the triglycerides were high, the high-density lipoprotein (HDL) cholesterol was reduced, and the ratio of total cholesterol over HDL cholesterol was high as compared with the controls. The RBC lipid composition expressed in mumol lipids/10(10) RBC showed significantly lower levels of free cholesterol, sphingomyelines, and phosphatidylcholine, which are the lipids principally located on the outer layer of the RBC membranes. These data suggest that in both IDD and NIDD patients, there may be a relation between these modifications in the RBC lipid composition and rheological impairment of the RBC.

Cholesterol↗

PubMed1982

Relationship between choline derivatives and mouse erythrocyte membrane antigens revealed by mouse monoclonal antibodies. I. Anticholine activity of anti-mouse erythrocyte monoclonal antibodies.

Different clones of mouse hybridomas, derived from the fusion of unstimulated mouse peritoneal cells with mouse myeloma cells, producing IgM monoclonal antibodies directed against the membrane of bromelain-treated mouse erythrocytes (MRBC(Br)) have been previously established. We have recently shown that one of these hybridomas produce, in ascites, antibodies cross-reacting with phosphorylcholine derivatives (trimethylammonium (TMA) derivatives). In this work the cross-reactivity for TMA derivatives of the monoclonal antibodies produced by 4 anti-MRBC(Br) hybridomas have been studied at the cell level (plaque-forming cells). Phosphorylcholine, choline bromide and p-aminophenyl-trimethylammonium were found to be potent specific inhibitors of plaque formation (anti MRBC(Br)). The hemolytic activities of ascites and tissue culture supernatants were studied and their inhibition by TMA derivatives was determined. Immunoglobulins from ascites purified on TMA immunoadsorbent column were analyzed by two-dimensional gel electrophoresis, their spectrotype was compared to the spectrotype of immunoglobulins from tissue culture supernatants from the same hybridoma radioactively tagged by internal incorporation of [14C]leucine. It could be shown without ambiguity that the PTMA column retained an IgM with the same characteristics as the IgM secreted in vitro.

Animals↗

PubMed1984

Spin-label studies of erythrocyte deformability. IV. Relation of electron spin resonance spectral change with deformation and orientation of erythrocytes in shear flow.

Electron spin resonance (ESR) spectra of spin-labeled human erythrocytes in shear flow are simulated to derive semi-empirical relations of the ESR spectral change with deformation and orientation of the cells by using a modified theoretical model developed for deformation and orientation of liquid drops. The six observed spectra at different shear stress values were simultaneously simulated by adjusting only two parameters. One parameter can be related to the ratio of the internal to the external viscosity, and the other to the elastic property of the cell membrane. From these results we have derived a semi-empirical relationship between the average deformation index or the orientation angle with a spectral measure, which characterizes the spectral shape change induced by shear stress. Thus, it becomes possible to obtain improved quantitative information on the rheological behavior of red blood cells by using the spin-label ESR method.

Electron Spin Resonance Spectroscopy↗

PubMed1981

Partition of thyroid hormone among erythrocyte cytosol, erythrocyte membrane and human plasma binding sites.

The partition of thyroid hormone among binding sites on plasma proteins, erythrocyte (RBC) membranes and cytoplasmic proteins has been examined in the context of recent direct estimates of intracellular RBC thyroid hormone content. Isotopic T3 and T4 uptakes by washed RBCs are identical (greater than 80% of tracer at 4 hr), but RBC binding when RBCs are suspended in plasma favors T3 (10% uptake vs. 2.5% for T4). The RBC cytosol: plasma T3 ratio is 1 : 21.

Blood Proteins↗

PubMed1986

Requirement for both MHC and non-MHC antigens residing on the same erythrocyte for donor erythrocyte-mediated prolongation of rat renal allograft survival.

Transfusions of highly purified LEW erythrocytes (E) administered to BN recipients prior to insertion of LEW kidneys markedly prolonged the survival of these allografts (greater than 35 days). Administration of E from syngeneic (BN), third-party (PVG), and MHC-congenic LEW.1N or BN.1L rats did not improve LEW kidney graft survival to the same extent (less than 14 days). BN.1L E were shown to carry at least the same quantity of LEW MHC antigens on their surface as LEW E, thus the failure to prolong LEW kidney graft survival is due to the absence of LEW non-MHC antigens from BN.1L E. Attempts to substitute for this deficiency by mixing LEW.1N E to BN.1L E prior to transfusion failed to restore the beneficial effect, demonstrating that donor E-mediated prolonged renal allograft survival requires the presence of both MHC and non-MHC alloantigens on the same E.

Animals↗

PubMed2000

The activity of erythrocyte enzymes and basic indices of peripheral blood erythrocytes from workers chronically exposed to mercury vapours.

The influence of occupational exposure to mercury vapours on the activity of the red cell enzymes [glucose-6-phosphate dehydrogenase (G-6PD), acetylcholinesterase (AChE), glutathione reductase (GR) and superoxide dismutase (SOD)], as well as on peripheral blood indices [erythrocyte number (RBC), HCT, Hb, MCHC] and on serum concentrations of iron, ferritin, transferrin and total iron binding capacity (TIBC), was assessed. Studies were carried out on 46 men aged between 21 and 56 years (X = 39 +/- 10.4) exposed to mercury vapours during their work from 7 months to 32 years (= 14.7 +/- 10.8). The control group consisted of 35 healthy workers aged between 20 and 54 years (X = 33.6 +/- 9.8) not exposed to chemical nor physical agents. In both groups studied, there were 50% and 34.3% smokers, respectively. The activity of studied red cell enzymes--G-6PD, AChE, GR and SOD--was estimated according to the colorimetric methods described by Beutler and expressed as international units per gram of hemoglobin (IU g Hb(-1)). Peripheral blood cell parameters were determined using an automatic cell counter. The concentration of serum iron and TIBC was determined using colorimetric methods (Beckman), while that of ferritin and transferrin by nephelometric methods. The time-weighted average (TWA) of mercury concentration in the air determined before the study was 0.0028 mg m(-3). Statistical analysis of the data was performed using either the Cochran and Cox C-test or the Student's t-test. The medium mercury concentration in the urine was 77.44 +/- 48.15 microg l(-1). In the group exposed to mercury vapours, a significant decrease was found in G-6PD activity (23.9%, P<0.001), GR (18.8%, P<0.001), and SOD (5%, P<0.001) with a concomitant increase in AChE activity (35.9%, P<0.001) was found. Moreover, a statistically significant increase occurred in HCT and RBC, and a decrease in MCV and MCHC as well as increases of ferritin (130.9%, P<0.001), transferrin (118.4%, P<0.001) and TIBC (11.2%, P<0.05). Our results indicate that long-term exposure to mercury vapours induces changes in the activity of red cell enzymes--G-6PD, AChE, GR and SOD--and may also influence other important hematological parameters of the peripheral blood.

Acetylcholinesterase↗

PubMed1980

Electron spin resonance and fluorescence observations on erythrocytes, erythrocyte membranes, 13762 MAT-A ascites adenocarcinoma cells, and their membranes, effects of membrane perturbations.

Membranes from erythrocytes or MAT-A 13762 tumor cells were labeled with the fatty acid spin probe I(5,10) or ANS and examined by spin resonance (ESR) or fluorescence polarization in the presence or absence of the perturbants EDTA, trypsin, glutaraldehyde, and dodecylsulfate. Extraction of cell membranes with hypotonic EDTA produced fragments in which the order parameters and fluorescence polarization values increased. Fluorescence polarization values using membranes labeled with diphenylhexatriene showed an apparent increase in membrane fluidity. A large portion of both I(5,10) and both fluorescence probes coextract with the peripheral membrane proteins in both membrane systems. Paramagnetic quenching of tryptophan fluorescence with I(5,10) and the spectral characteristics of ANS in these membranes indicated further that significant amounts of both probes bind either at or near the protein-lipid interface or directly to protein moieties. Trypsinization of cell membranes, which preferentially cleaves the large cytoskeletal proteins, fragmented the membranes and reduced the ESR order parameter. Glutaraldehyde immobilized I(5,10) in both types of membranes. These studies suggest that the association of cytoskeletal proteins with the membrane does not have any pronounced, consistent effect on biophysical properties of the bilayer. Attempts to apply these same probes to studies of the plasma membranes of intact cells were not successful because of the diffusion of the probes into the cells. These studies also point out some difficulties in using probe-group techniques to determine the nature of changes in bilayer structural parameters and emphasize the need for a better understanding of probe-group localization and behavior in such studies.

Adenocarcinoma↗

PubMed1983

Studies on avian erythrocyte metabolism. XIII. Changing organic phosphate composition in age-dependent density populations of chicken erythrocytes.

These studies were performed to determine whether the erythrocytes (RBC's) of chickens are able to alter the concentrations of organic phosphates, particularly inositol pentakis (dihydrogen phosphate) (inositol-P5), in response to anemia. Acute anemia with 33.5% reticulocytes (retics) in the peripheral blood of 4-month-old White Leghorn cockerels was produced after two successive days of controlled bleeding. Five populations of RBC's were prepared from blood of these anemic birds based upon age-dependent density by angle rotor centrifugation. The relative increase in age of Fraction 1 (younger cells) through Fraction 5 (oldest cells) was verified by increased hemoglobin concentration and decreased retic count and cell volume. The acid aqueous-soluble phosphates from each RBC fraction were extracted, fractionated by ion exchange column chromatography, and the concentration of inorganic phosphate (Pi), adenosine triphosphate (ATP), and inositol-P5 quantitated by wet-ash phosphate analysis. Determination of Pi, ATP, and inositol-P5 in Fraction 1 (younger cells, 7.4% retics) from the initial (Day 1) blood withdrawn gave 4.3, 5.7, and 18.6 mumoles Pi/ml RBC, respectively. On Day 4 of controlled-bleeding, Pi, ATP, and inositol-P5 concentrations in Fraction 1 (95.1% retics) were 12.7, 10.6, and 12.3 mumoles Pi/ml RBC, respectively. On Day 11, after 1 week recovery from controlled-bleeding, the values for Pi, ATP, and inositol-P5 in Fraction 1 (37.7% retics) were 5.0, 5.4, and 19.0 mumoles Pi/ml RBC, respectively, which were similar to the values before bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3-Diphosphoglycerate↗

PubMed1985

[Role of erythrocyte deformability in erythrocyte transit time and bioavailability of O2].

The bioavailability of oxygen and its transfer towards all of the cells of the body essentially depends on the flow rate of red blood cells in the capillaries, which often have a smaller diameter than the red cell itself. The authors discuss the results obtained for the mean transit time of erythrocytes, based on microfiltration through artificial polycarbonate capillaries with a diameter of 5 microns, a length of 13 microns and a density of 4.10(5) pores/cm2.

Biological Availability↗

PubMed1980

[Relationship between the mechanism of erythrocyte sensitization by proteins and the spatial interrelationship between immunoglobulins and their fragments and the surface of formalin treated erythrocytes].

The methods of serological analysis have been used to study the immunochemical (antibody and antigenic) properties and hemosensitizing activity of a number of immunoglobulin sensitins: immune serum, its fractions (globulin, 7S, 19s, gamma-globulin), as well as pure antibodies and their F(ab)2-and Fab-fragments. According to the findings obtained in this study, the hemosensitizing activity of sensitins may be classified as immunoglobulin activity and antigenic activity. All sensitins have been found to have both immunoglobulin and antigenic activity, with the exception of Fab-fragments having only antigenic activity. The results of this study and their comparison with the known data on the fine structure and properties of IgG form the basis for drawing up the picture of the possible location of IgG and their fragments on the surface of a tanned erythrocyte.

Adsorption↗

PubMed1986

Structure and composition of the cytoskeleton of nucleated erythrocytes: III. Organization of the cytoskeleton of Bufo marinus erythrocytes as revealed by freeze-dried platinum-carbon replicas and immunofluorescence microscopy.

Platinum-carbon (Pt-C) replicas of freeze-dried erythrocyte cytoskeletons of the toad, Bufo marinus, were prepared using a modified Balzers 300 system. Examination in stereo of replicas of the microtubule-containing marginal band revealed filaments projecting from the microtubule walls to form links between adjacent microtubules. These cross-bridging proteins may bundle the microtubules into the configuration of the marginal band (MB) and may also serve to stabilize the structure. The MB appears to have linkages to components of the surface-associated cytoskeleton (SAC). The SAC forms a continuous matrix that spreads across the upper and lower surfaces of the cell adjacent to the plasma membrane and extends around the outer perimeter of the MB. Thus, the SAC encapsulates the MB and the central nucleus. After lysis, the elements of the cytoskeleton remain in a configuration similar to that found in the whole cell. Spectrin (fodrin) and actin were identified by immunofluorescence in the region of the SAC. When labeled with antibodies specific for vimentin and synemin, a network of intermediate filaments can be detected in the region between the nucleus and the MB. These vimentin filaments are also enclosed within the SAC and appear in Pt-C replicas to emerge from the area of the nuclear envelope. As the filaments extend toward the periphery of the cell, they form attachments to the SAC. Attachments of intermediate filaments to both the nucleus and the SAC thus appear to anchor the nucleus in its central position within the cytoskeleton.

Animals↗