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At least 109 records · Page 6Linked to original sources
PubMed1995

Reactivity of anti-erythrocyte antibody induced by Babesia gibsoni infection against aged erythrocytes.

Effects of ageing treatment of erythrocytes to binding activity of the anti-erythrocyte antibody(s) in the serum of dogs infected artificially with Babesia gibsoni were examined by enzyme-linked immunosorbent assay (ELISA) using fixed cell antigen. When erythrocytes made senescent by two artificial ageing treatments, one of which was storing erythrocytes at 37 degrees C in medium for some days and the other was oxidation of erythrocytes with phenylhydrazine, reactivity of anti-erythrocyte antibody(s) in the infected serum to both types of treated erythrocytes was increased. These results suggest that such antibody(s) could play a role as one of the causes of anemia in canine babesiosis.

Anemia↗
PubMed2004

Structural analogs of sialic acid interfere with the binding of erythrocyte binding antigen-175 to glycophorin A, an interaction crucial for erythrocyte invasion by Plasmodium falciparum.

Plasmodium falciparum causes the most virulent form of malaria and remains a major worldwide health problem. The erythrocytic development of P. falciparum relies on parasite invasion of host erythrocytes, a process mediated in part by the interaction of erythrocyte binding antigen 175 (EBA-175) with the erythrocyte receptor glycophorin A (GA). The binding domain of EBA-175 that interacts with glycophorin A is a approximately 330 residues module called F2. Several studies have shown that F2 recognizes both sialic acids and the protein backbone on glycophorin A. Here, we have developed ELISA-based quantitative F2-GA binding assays. We also performed a series of competitive inhibition assays to block the F2-GA interaction using a variety of sialic acid analogs. Our data show that both 2,3-didehydro-2-deoxy-N-acetyl neuraminic acid (DANA) and 3'-N-acetyl neuraminyl-N-acetyl lactosamine are excellent inhibitors of the F2-GA interaction. Moderate levels of inhibition were also observed with monomers or oligomers of N-acetyl neuraminic acid (sialic acid). Furthermore, we show that DANA is able to significantly inhibit the invasion of erythrocytes by P. falciparum. Together, our ELISA-based binding assays and in vitro inhibition of erythrocyte invasion data suggest that small variations in the structures of DANA and related inhibitors can result in even more potent invasion inhibitory activities. Our studies provide a platform for the development of high potency inhibitors of the F2-GA interaction using high throughput drug discovery technologies. Such compounds may form part of inhibitor cocktails, which aim to block invasion of erythrocytes by P. falciparum.

Animals↗
PubMed1997

Effect of donor age on the susceptibility of erythrocytes and erythrocyte membranes to cumene hydroperoxide-induced oxidative stress.

A comparative study on erythrocytes and erythrocyte membranes of healthy elderly and young adults was carried out to understand how the antioxidant defense capacity is effected by aging. The levels of endogenous malondialdehyde and Ca(2+)-ATPase activity were taken as indices of oxidative damage. In addition, chemiluminescence measurements were performed on intact erythrocytes. The susceptibility of these parameters to in vitro cumene hydroperoxide, under low oxidant level that does not induce hemolysis, was also taken as an age-related indicator of the endogenous peroxidative potential of the erythrocytes. Our data showed that the content of malondialdehyde and Ca(2+)-ATPase activity did not change with age. Furthermore, the susceptibility of intact erythrocytes to oxidative stress did not change in the elderly group. However, under the same conditions erythrocyte membranes were more susceptible to oxidative damage in the elderly than young adults. Our results also showed that antioxidant defenses were overwhelmed in intact erythrocytes of the elderly at high concentrations of cumene hydroperoxide.

Adult↗
PubMed2002

Clearance of senescent erythrocytes: wheat germ agglutinin distribution on young and old human erythrocytes.

To add an additional aspect to the process of recognition and removal of senescent human erythrocytes from the circulation, the binding of wheat germ agglutinin (WGA) to separated young, old and sialidase-treated human erythrocytes is evaluated with the immune-electron microscopical method. WGA/gold conjugate binding to old erythrocytes was lower (27%) than to young erythrocytes and even lower following treatment with sialidase (82%), exhibiting a clustered, non-continuous labeling pattern in all three erythrocyte populations, thus showing a possible redistribution of WGA binding sites. The decrease in bound WGA/gold particles correlates well with the previously reported decrease in surface sialic acid on old erythrocytes. The binding of WGA/gold are indicative of the changes occurring on erythrocyte membrane surfaces when interacting with different agglutinins.

Cellular Senescence↗
PubMed2003

A novel erythrocyte binding antigen-175 paralogue from Plasmodium falciparum defines a new trypsin-resistant receptor on human erythrocytes.

The recognition and invasion of human erythrocytes by the most lethal malaria parasite Plasmodium falciparum is dependent on multiple ligand-receptor interactions. Members of the erythrocyte binding-like (ebl) family, including the erythrocyte binding antigen-175 (EBA-175), are responsible for high affinity binding to glycoproteins on the surface of the erythrocyte. Here we describe a paralogue of EBA-175 and show that this protein (EBA-181/JESEBL) binds in a sialic acid-dependent manner to erythrocytes. EBA-181 is expressed at the same time as EBA-175 and co-localizes with this protein in the microneme organelles of asexual stage parasites. The receptor binding specificity of EBA-181 to erythrocytes differs from other members of the ebl family and is trypsin-resistant and chymotrypsin-sensitive. Furthermore, using glycophorin B-deficient erythrocytes we show that binding of EBA-181 is not dependent on this sialoglycoprotein. The level of expression of EBA-181 differs among parasite lines, and the importance of this ligand for invasion appears to be strain-dependent as the EBA-181 gene can be disrupted in W2mef parasites, without affecting the invasion phenotype, but cannot be targeted in 3D7 parasites.

Animals↗
PubMed1997

Quantitative and qualitative studies of micronucleus induction in mouse erythrocytes using flow cytometry. I. Measurement of micronucleus induction in peripheral blood polychromatic erythrocytes by chemicals with known and suspected genotoxicity.

Quantitative and qualitative aspects of the in vivo micronucleus-inducing potential of five chemicals were studied using flow cytometric enumeration of micronucleated polychromatic peripheral blood erythrocytes in mice. The chemicals were hydroquinone, vinblastine sulphate, chloral hydrate (tested in two different mouse strains), 5-bromo-2-deoxyuridine and 2-chlorobenzylidene malonitrile. Repeat samplings of peripheral blood were made at 0, 24, 40, 48 and 72 h and for low doses of 5-bromo-2-deoxyuridine 96 h after i.p. treatment. The agents hydroquinone (lowest effective dose 25 mg/kg), vinblastine sulphate (lowest effective dose 0.05 mg/kg) and 5-bromo-2-deoxyuridine (lowest effective dose 200 mg/kg) gave rise to significant increases in the frequencies of micronucleated polychromatic erythrocytes. No significant induction of micronucleated polychromatic erythrocytes by 2-chlorobenzylidene malonitrile or chloral hydrate was found. The frequencies of induced micronucleated polychromatic erythrocytes peaked at 40 h after hydroquinone treatment, at 48 h after vinblastine treatment and at 72 h after 5-bromo-2-deoxyuridine treatment with evident dose-dependent differences in the kinetics of the induction of micronucleated polychromatic erythrocytes. The mean relative Hoechst 33342 fluorescence of the populations of induced micronucleated polychromatic erythrocytes was used as an indicator of the DNA content of induced micronuclei. These values were found to be in agreement with the presumed mechanisms of micronucleus induction for hydroquinone, vinblastine sulphate and 5-bromo-2-deoxyuridine. Flow cytometric enumeration of micronucleated polychromatic erythrocytes in peripheral blood is an efficient method for the study of in vivo micronucleus induction, combining rapid analysis and high sensitivity with information on possible mechanisms of micronucleus induction. The method also allows a substantial reduction in the number of animals needed.

Animals↗
PubMed1985

Evidence for sialylated type 1 blood group chains on human erythrocyte membranes revealed by agglutination of neuraminidase-treated erythrocytes with Waldenström's macroglobulin IgMWOO and hybridoma antibody FC 10.2.

Haemagglutination studies have been performed with untreated and neuraminidase-treated human erythrocytes of the three Lewis antigen types Le(a-b-), Le(a+b-) and Le(a-b+) using two monoclonal antibodies, IgMWOO and FC 10.2, which were previously shown to recognize the type 1 based blood group chains: Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc/GlcNAc (for explanation of abbreviations see table IV legend). Both antibodies behaved as cold agglutinins with neuraminidase-treated but not with untreated erythrocytes of the three Lewis antigen types. Neuraminidase-treated erythrocytes of i antigen type were similarly agglutinated. This haemagglutination was specifically inhibited by the type 1 based milk oligosaccharide lacto-N-tetraose. Thus, there is strong evidence for the occurrence of sialylated type 1 chains on human erythrocyte membranes of I and i antigen types. In addition, evidence for the presence of type 1 chains which are both sialylated and fucosylated was obtained by (1) haemagglutination of Le(a+b-) erythrocytes with the monoclonal antibody 19.9; (2) increased haemagglutination of neuraminidase-treated erythrocytes with anti-H antibodies of Bombay serum; (3) increased haemagglutination of neuraminidase-treated Le(a+b-) cells with anti-Lea antibodies, and (4) the appearance of Lea antigen activity on neuraminidase-treated erythrocytes of Le(a-b+) type.

ABO Blood-Group System↗
PubMed1987

Monocyte-erythrocyte interaction in autoimmune haemolytic anaemia in relation to the number of erythrocyte-bound IgG molecules and subclass specificity of autoantibodies.

Monocyte-erythrocyte interaction in patients with autoimmune haemolytic anaemia (AIHA) was assessed by phagocytosis and rosette assays. In most patients, a relationship was observed between haemolysis and the phagocytosis of their own erythrocytes by allogenic peripheral monocytes. An evaluation of the number of immunoglobulins on patient erythrocytes and IgG subclasses of autoantibodies shows that in patients with only IgG1 antibody or with additional IgG2 or/and IgG4, phagocytosis was always observed when the number of erythrocyte-bound IgG molecules was above 2,000. On the other hand, in all patients where IgG3 was detectable, phagocytosis was observed even if the amount of IgG was as low as 230 molecules per erythrocyte. Similar observations were made in the rosette assay. Generally, the number of erythrocyte-bound IgG and the presence of phagocytosis were correlated with the degree of haemolysis, but there were exceptions, i.e. the amount of IgG and phagocytosis were high but there was no evidence of haemolysis, or where there was little IgG, no phagocytosis but haemolysis was present. Our data do not indicate that erythrocytes from AIHA are preferentially bound to autologous monocytes.

Anemia, Hemolytic, Autoimmune↗
PubMed1985

Selenium supplementation in X-linked muscular dystrophy. Effects on erythrocyte and serum selenium and on erythrocyte glutathione peroxidase activity.

The selenium concentrations in serum and erythrocytes and the erythrocyte glutathione peroxidase activity were determined in 15 boys with the Duchenne type and in 5 boys with the Becker type of X-linked muscular dystrophy before and during long-term selenium and alpha-tocopherol supplementation and compared with values in unsupplemented controls. The purpose of the treatment was to improve the muscular strength. Twelve of the 20 patients had pretreatment levels of selenium in serum that were within the 95% confidence limit of the unsupplemented control children. The values in 2 patients, both with the Duchenne type of muscular dystrophy, fell below this level. Selenium supplementation in a daily dose of 6 micrograms/kg/day for 6 months caused a substantial rise in both serum and erythrocyte selenium, suggesting suboptimal pretreatment body contents of selenium. The greatest increases in both serum and erythrocyte selenium were observed in subjects with initially low selenium levels. Only in 4 of the 20 patients did the selenium supplementation result in a significant rise in erythrocyte glutathione peroxidase activity. As no sure improvement was noted in muscular strength during this treatment period, the Se dose was increased to 20 micrograms/kg/day. This resulted in a further rise in both serum and erythrocyte selenium, but not in erythrocyte glutathione peroxidase activity.

Adolescent↗
PubMed1989

Increased plasma and erythrocyte selenium concentrations but decreased erythrocyte glutathione peroxidase activity after selenium supplementation in children with Down syndrome.

An investigation was made of the activity of glutathione peroxidase (GSH-Px) in erythrocytes and the levels of selenium in plasma and erythrocytes before, during and after selenium supplementation in children with Down syndrome (DS). This subject is of interest since it has been suggested that selenium supplementation could enhance the GSH-Px activity in erythrocytes, probably leading to improved protection against oxygen radicals, which might cause damage by lipid peroxidation, especially in the brain. Forty-eight children with DS were treated with selenium-rich yeast tablets (10 micrograms/kg body weight/day) for 6 months. The supplementation was well tolerated and no side effects were observed. Selenium supplementation resulted in increased concentrations of selenium both in plasma and erythrocytes, but decreased GSH-Px-activity in erythrocytes. Plasma and erythrocyte selenium levels but almost regained the initial values 12 months after termination of the supplementation. Erythrocyte GSH-Px activity, on the other hand, remained reduced and did not return to the presupplementation levels. Until we gain more knowledge about the biological functions of selenium in man and the role of oxygen metabolism in the development of presenile dementia in DS, universal selenium supplementation in DS patients cannot be recommended.

Adolescent↗
PubMed1992

Plasmodium falciparum-infected erythrocytes do not adhere well to C32 melanoma cells or CD36 unless rosettes with uninfected erythrocytes are first disrupted.

Plasmodium falciparum malaria parasites modify the human erythrocytes in which they grow so that some parasitized erythrocytes (PE) can cytoadhere (C+) to host vascular endothelial cells or adhere in rosettes (R+) to uninfected erythrocytes. These C+ and R+ adherence properties of PE appear to mediate much of the pathogenesis of severe malaria infections, in part by blocking blood flow in microvessels. From one parasite strain, PE were selected in vitro for C+ R+ or C+ R- adherence properties and examined in model adherence assays. The C+ R+ PE cytoadhered poorly to C32 melanoma cells or to immobilized CD36 in a settled-cell assay when uninfected human erythrocytes were present and formed rosettes with PE. C+ R- PE adhered well in the same assays. However, C+ R+ PE adhered very well, even better than C+ R- PE, when the rosettes were disrupted and the C+ R+ PE were purified. Adding back rabbit erythrocytes, which do not form rosettes with C+ R+ PE, had simply a dilutional effect. The ability of rosettes to interfere with the detection of adherence must be dealt with in all future assays of malarial PE adherence. Individual PE were observed attached simultaneously to C32 cells and to a few erythrocytes, suggesting that C+ and R+ adherence properties are coexpressed on the same PE. Coexpression of these adherence properties on the same PE may have pathological importance in vivo, where passage of rosettes through capillaries may shear uninfected erythrocytes from rosetted PE and allow direct PE attachment to postcapillary venule walls before rosettes reform.

Animals↗
PubMed1975

The histones of rainbow trout erythrocytes include an erythrocyte-specific histone.

The erythrocyte histones of rainbow trout were compared with those of goose by polyacrylamide gel electrophoresis. A band analogous to goose erythrocyte-specific histone V, but not identical in relative mobility or quantity, was found to be a component of trout erythrocyte histone. A similar component was also found in carp erythrocyte histone, but it was absent from trout liver histone. To reveal this band clearly, it was advantageous to displace the histone III monomer by oxidation. To verify the character of this protein, each of the main erythrocyte histones of trout were purified by chromatography on Amberlite CG-50, eluted with guanidinium chloride, and then further purified by exclusion chromatography on Bio-Gel P-60. Amino acid compositions of corresponding trout and goose histones, including that of the erythrocyte-specific histone, were sufficiently similar to establish their analogous identities. In general, the chromatographic and electrophoretic properties of histones I, IIb1, IIb2, and V from trout differed more from those of goose, than did their gross amino acid compositions. Comprehensive fractionation and characterization is necessary to extablish identities of corresponding histone fractions, An extensive quantitative variability was found among erythrocyte-specific histones of fish. This must be reconciled with hypothetical roles for this histone in erythropoiesis.

Amino Acids↗
PubMed1983

Human erythrocyte antigens. Regulation of expression of a novel erythrocyte surface antigen by the inhibitor Lutheran In(Lu) gene.

Our study describes a novel human erythrocyte protein antigen, the expression of which is regulated by the rare Lutheran inhibitor In(Lu) gene. We have produced a monoclonal antibody (A3D8) that bound strongly to erythrocytes from subjects with Lutheran phenotypes Lu(a+b+), Lu(a+b-), and Lu(a-b+) but bound negligibly to erythrocytes from subjects with the dominant form of Lu(a-b-) phenotype, reflecting inheritance of the In(Lu) gene. Importantly, erythrocytes from an individual with the recessive form of Lu(a-b-) phenotype (i.e., absence of the In(Lu) gene and absence of genes encoding for Lutheran antigens) showed reactivity with A3D8 antibody comparable to that seen with Lu(a+) or Lu(b+) erythrocytes. A3D8 antigen activity was also found on all leukocytes and in serum and plasma; this activity also appeared to be regulated by the In(Lu) gene in serum, plasma, and on a subset of leukocytes. Thus, we have identified a human erythrocyte protein whose expression is modified by the In(Lu) gene. This knowledge that such an antigen exists on erythrocytes and in normal plasma should allow further studies into the molecular genetics of the In(Lu) gene and into the functional and structural significance of the A3D8 antigen.

Animals↗
PubMed2005

A spectrophotometric micromethod for determining erythrocyte protoporphyrin-IX in whole blood or erythrocytes.

An increased concentration of erythrocyte protoporphyrin-IX in whole blood or erythrocytes is a valuable diagnostic indicator for acquired porphyrias, e.g., iron deficiency anemia and lead poisoning, and for inherited porphyrias. We developed a spectrophotometric micromethod for determining erythrocyte protoporphyrin-IX. In this method, exhaustive release of erythrocyte porphyrins is achieved using hydroquinone and formic acid. The clean-up procedure for 50 microL of whole blood or erythrocytes covers three steps of liquid/liquid solvent partition: two partitions using diethyl and diisopropyl ether and HCl 2.5 mol/L, and one buffered step using ammonium formate. Determinations of erythrocyte protoporphyrin-IX are possible by: (a) absorption using three wavelengths, Rimington's constant and a millimolar absorptivity coefficient m epsilon(408.8)=294.3 L x mmol(-1) x cm(-1) according to With; and (b) 2nd derivative, which is linked to m epsilon(408.8). Determination of erythrocyte protoporphyrin-IX using a 2nd derivative algorithm showed better spectral resolution and higher sensitivity at a five-fold lower detection limit compared to absorption. Within-run precision of medium and high levels was found for absorption and for 2nd derivative with a coefficient of variation (CV) of 1.4-1.9% (n=10). Total precision evaluated was CV=2.5-8.3% (n=20). Levels of reference intervals could only be measured using the 2nd derivative (CV 2.9%). Linearity was proved to E=1.0. Recoveries of protoporphyrin-IX ranged from 95.3% to 103.0%. Method comparison was carried out using a fluorimetric reference method (Piomelli). Reference intervals for gender groups are discussed.

Algorithms↗
PubMed1976

[Binding and distribution of chlordiazepoxide (Radepur) and its metabolites in the erythrocyte-plasma and erythrocyte-buffer systems].

The distribution and the free concentration of chlorodiazepoxide, desmethyl-chlorodiazeoxide and demoxepam in the systems erythrocyte-plasma and erythrocyte-buffer is determined. In both systems the substances are bound by erythrocytes. A constant ratio of distribution between erythyrocyte-plasma and erythrocyte-buffer, respectively, is established beyond therapeutic concentrations. The association constants (dual reciprocal plot) of these substances are of the order of 10(4)-1-M-1. They are the same for erythrocytes and plasma. The specific binding of erythrocytes is 20-35 fold less than with plasma proteins. It is concluded that the erythrocytes are a binding intravascular subcompartment for chlorodiazepoxide and its metabolites.

Biotransformation↗
PubMed1983

Light-induced release of protoporphyrin, but not of zinc protoporphyrin, from erythrocytes in a patient with greatly elevated erythrocyte protoporphyrin.

A patient with greatly increased erythrocyte protoporphyrin, but normal porphyrins in urine and feces, is described. The patient later developed a malignant lymphoma, and the reason why she accumulated protoporphyrin in her erythrocytes is not known. The protoporphyrin in the erythrocytes consisted of two types of protoporphyrin, free protoporphyrin (30%) and zinc protoporphyrin (70%). Upon irradiation of erythrocytes in the absence of albumin, protoporphyrin and zinc protoporphyrin, which were both bound to hemoglobin, were released. In contrast, when the irradiation was carried out in the presence of albumin, the photohemolysis was negligible, and there was release of free protoporphyrin, but not of zinc protoporphyrin, from the erythrocytes. In vivo albumin is present in the plasma and the results may help to explain why patients with erythropoietic protoporphyria (erythrocytes containing free protoporphyrin) are photosensitive, whereas patients with lead intoxication and iron deficiency (erythrocytes containing zinc protoporphyrin) are not.

Aged↗
PubMed1978

The survival time of rabbit's erythrocytes. I. Elimination of auto- and allogenic erythrocytes radioactively labeled with chromium 51Cr from circulation.

The speed of eliminating allogenic erythrocytes labeled with 51Cr from circulation was examined. Donor's erythrocytes with AFHR phenotype were injected to the recipient with FR phenotype. A fast elimination of allogenic erythrocytes was observed, T 1/2 = 7.6 days. The survival time of autogenic erythrocytes was T 1/2 = 18.2 days. In sera of those rabbits to whom allogenic erythrocytes had been injected, no anti-erythrocyte antibodies against the donor's hemocytes appeared.

Animals↗
PubMed1979

Interaction of plasma lipoproteins with erythrocytes. I. Alteration of erythrocyte morphology.

Intact erythrocytes incubated in the presence of low density lipoproteins (LDL) undergo a time-dependent morphologic transformation from biconcave discs to spherocytes within 4 h. No shape change is observed when erythrocytes are incubated with high density lipoproteins (HDL). The LDL-induced change in erythrocyte morphology occurs without concomitant leakage of hemoglobin from the cell or depletion of intracellular ATP; no change in the distribution of the major lipids of the erythrocyte membranes was detected. The alteration of morphology does require attachment of LDL to the erythrocyte surface. The LDL-induced morphologic alteration is inhibited by HDL, but not by serum albumin. HDL prevent the attachment of LDL to the cell membrane; however, the HDL subfractions, HDL2 and HDL3, are only partially effective. These data suggest that normal erythrocyte morphology and cell function may depend on the concentration and composition of the circulating lipoproteins.

Adenosine Triphosphate↗