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‣ Linkage of cytosolic peroxiredoxin 2 to erythrocyte membrane imposed by hydrogen peroxide-induced oxidative stress

Rocha, Susana; Costa, Elísio; Coimbra, Susana; Nascimento, Henrique; Catarino, Cristina; Rocha-Pereira, Petronila; Quintanilha, Alexandre; Belo, Luís; Santos-Silva, Alice
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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Human erythrocyte peroxiredoxin 2 (Prx2) is a typical 2-cys cytosolic peroxiredoxin with thiol-dependent hydrogen peroxide scavenger activity. In a previous work, we reported Prx2 erythrocyte membrane linkage in some Hereditary Spherocytosis patients and that it seemed to be related to oxidative stress. The aim of the present work was to determine if Prx2 linkage to erythrocyte membrane could be induced by oxidative stress mediated by H2O2 and to further understand how and why this process occurs. We performed in vitro assays in which catalase or both Hb autoxidation and catalase were inhibited, under H2O2-induced oxidative stress conditions. Erythrocyte membrane linked Prx2 was detected by immunoblotting and quantified by densitometry. As oxidative stress markers, we determined membrane bound hemoglobin and lipid peroxidation, and we found that their values increased with H2O2 concentration. Prx2 linkage to the membrane also rose with increasing H2O2 concentration, and was only observed when the oxidized form of the enzyme was present in the cytosol. Oxidized Hb and Prx2 membrane linkages appear to be independent processes, although, both result from oxidative stress and may be useful as oxidative stress and/or erythrocyte damage/senescence markers.

‣ An overview about erythrocyte membrane

Oliveira, Sofia de; Saldanha, Carlota
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
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© 2010 – IOS Press and the authors. All rights reserved; In the sixties and seventies, erythrocytes or red blood cells (RBCs) were extensively studied. Much has been learnt particularly concerning their metabolism and gas transporter function. In the past decade, the use of new approaches and methodologies, such as proteomic analysis, has contributed for a renewed interest on the erythrocyte. Recent studies have provided us with a more detailed and comprehensive picture on the composition and organization of its cellular membrane that will be the main subject of this minireview. Unexpectedly, it has been recognized that this cell expresses several adhesion molecules on its surface, like other cellular types such blood circulating cells or endothelial cells. Taking into consideration the cellular functions of the erythrocyte, the clarification of the role of those adhesion molecules may in the future open new horizons for the biological significance of this cellular player.

‣ Erythrocyte as a link between basic and clinical research

Saldanha, C.; Almeida, J. P. Lopes de
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
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© 2011 – IOS Press and the authors; We review the major hemorheological experimental studies that show the erythrocyte aggregation as a link between basic and clinical research. The results of the clinical cross-sectional and longitudinal studies presented here will highlight the possible association between erythrocyte aggregation and plasma fibrinogen. Basic studies conducted in vitro are also mentioned as for its relevance in answering questions raised in clinical settings, as well as and in understanding the underlying influent factors in the erythrocyte tendency to aggregate and disaggregate.

‣ An in vitro study of adrenaline effect on human erythrocyte properties in both gender

Hilário, Sandra; Saldanha, Carlota; Martins e Silva, J.
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //2003 Português
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© 2003 – IOS Press. All rights reserved; The possibility that erythrocytes may function as a reservoir for noradrenaline and adrenaline and as a modulator of circulating catecholamine concentrations had been suggested. The aim of this work was to study the adrenaline effect on erythrocyte membrane fluidity, acetylcholinesterase (AChE) enzyme activity, P50 and erythrocyte deformability and also to verify if the role of adrenaline on erythrocyte properties is sex-dependent. Blood samples from 42 healthy donors were obtained, and its aliquots incubated 30 min without (control) and with 10−5 M concentrations of adrenaline alone (A1) and adrenaline with an α and an β-blocker (A2). Results demonstrate that initial AChE values in female are higher (p≤0.01) than male values. In female, adrenaline decreases AChE activity either when α and β-adrenergic receptors are blocked (p≤0.01) or when they are not. In male, adrenaline increases AChE activity when none of adrenergic receptors are blocked. Control values of male and female erythrocyte membrane fluidity are very similar but behaviour became differently (p≤0.05) when adrenaline is present because it decreases male and increases female values. Gender differences in erythrocyte deformability are verified at high shear stress values (p≤0.02). In female we have also registered the existence of an inverse significant correlation (r = −0.62) between membrane rigidity and AChE activity in A2 values. Adrenaline increases p50 values (p≤0.03) in both sexes. Peripheral blood film has shown echinocytes when adrenaline 10−5 M is present. We conclude that in this in vitro study sex-related differences in erythrocyte acetylcholinesterase enzyme activity...

‣ The effect of sodium fluorescein angiography on erythrocyte properties

Sargento, L.; Zabala, L.; Saldanha, C.; Souza-Ramalho, P.; Martins e Silva, J.
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //1998 Português
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© 1998 – IOS Press. All rights reserved; Sodium fluorescein angiography is a widely used routine ophthalmological diagnostic procedure which enables the study of chorioretinal microcirculation and consists of the injection of sodium fluorescein into the systemic bloodstream. The aim of the present study was to evaluate whether or not fluorescein interferes with erythrocyte properties during the angiographic procedure. In a group of 37 patients, 26 with non-insulin-dependent diabetes mellitus (DM) with and without retinopathy, and 11 without diabetes mellitus (non-DM) although affected by other ophthalmological diseases, all undergoing routine angiography, blood samples were drawn before (T0) and 30 min (T30) after fluorescein injection. The erythrocyte aggregation index (EAI), membrane lipid fluidity and erythrocyte acetylcholinesterase activity were determined in both groups. After fluorescein injection there was no statistical change in EAI and erythrocyte membrane fluidity in either group. Erythrocyte acetylcholinesterase activity, a marker of membrane protein integrity, decreased significantly (p < 0:01) in the DM group. Membrane lipid fluidity did not change with fluorescein injection, however, (i) in the DM group erythrocyte membranes became more rigid than in the non-DM (DPH: p < 0:01); (ii) EAI and membrane lipid fluidity became significantly correlated (r = 0:6263...

‣ Behaviour of human erythrocyte aggregation in presence of autologous lipoproteins

Saldanha, C; Loureiro, J; Moreira, C; Silva, J
Fonte: Hindawi Pub Publicador: Hindawi Pub
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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The aim of this work was to evaluate in vitro the effect of autologous plasma lipoprotein subfractions on erythrocyte tendency to aggregate. Aliquots of human blood samples were enriched or not (control) with their own HDL-C, LDL-C, or VLDL-C fractions obtained from the same batch by density gradient ultracentrifugation. Plasma osmolality and erythrocyte aggregation index (EAI) were determined. Blood aliquots enriched with LDL-C and HDL-C showed significant higher EAI than untreated aliquots, whereas enrichment with VLDL-C does not induce significant EAI changes. For the same range of lipoprotein concentrations expressed as percentage of osmolality variation, the EAI variation was positive and higher in presence of HDL-C than upon enrichment with LDL-C (P < 0.01). Particle size, up to LDL diameter values, seems to reinforce erythrocyte tendency to aggregate at the same plasma osmolality (particle number) range of values.

‣ Partial recovery of erythrocyte glycogen in diabetic rats treated with phenobarbital

Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/1997 Português
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Erythrocytes may play a role in glucose homeostasis during the postprandial period. Erythrocytes from diabetic patients are defective in glucose transport and metabolism, functions that may affect glycogen storage. Phenobarbital, a hepatic enzyme inducer, has been used in the treatment of patients with non-insulin-dependent diabetes mellitus (NIDDM), increasing the insulin-mediated glucose disposal. We studied the effects of phenobarbital treatment in vivo on glycemia and erythrocyte glycogen content in control and alloxan-diabetic rats during the postprandial period. In control rats (blood glucose, 73 to 111 mg/dl in femoral and suprahepatic veins) the erythrocyte glycogen content was 45.4 ± 1.1 and 39.1 ± 0.8 µg/g Hb (mean ± SEM, N = 4-6) in the femoral artery and vein, respectively, and 37.9 ± 1.1 in the portal vein and 47.5 ± 0.9 in the suprahepatic vein. Diabetic rats (blood glucose, 300-350 mg/dl) presented low (P<0.05) erythrocyte glycogen content, i.e., 9.6 ± 0.1 and 7.1 ± 0.7 µg/g Hb in the femoral artery and vein, respectively, and 10.0 ± 0.7 and 10.7 ± 0.5 in the portal and suprahepatic veins, respectively. After 10 days of treatment, phenobarbital (0.5 mg/ml in the drinking water) did not change blood glucose or erythrocyte glycogen content in control rats. In diabetic rats...

‣ Erythrocyte glucose-6-phosphate dehydrogenase from Brazilian opossum Didelphis marsupialis

Barretto,O.C. de O.; Oshiro,M.; Oliveira,R.A.G.; Fedullo,J.D.L.; Nonoyama,K.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2006 Português
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In a comparative study of erythrocyte metabolism of vertebrates, the specific activity of glucose-6-phosphate dehydrogenase (G6PD) of the Brazilian opossum Didelphis marsupialis in a hemolysate was shown to be high, 207 ± 38 IU g-1 Hb-1 min-1 at 37ºC, compared to the human erythrocyte activity of 12 ± 2 IU g-1 Hb-1 min-1 at 37ºC. The apparent high specific activity of the mixture led us to investigate the physicochemical properties of the opossum enzyme. We report that reduced glutathione (GSH) in the erythrocytes was only 50% higher than in human erythrocytes, a value lower than expected from the high G6PD activity since GSH is maintained in a reduced state by G6PD activity. The molecular mass, determined by G-200 Sephadex column chromatography at pH 8.0, was 265 kDa, which is essentially the same as that of human G6PD (260 kDa). The Michaelis-Menten constants (Km: 55 µM) for glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate (Km: 3.3 µM) were similar to those of the human enzyme (Km: 50-70 and Km: 2.9-4.4, respectively). A 450-fold purification of the opossum enzyme was achieved and the specific activity of the purified enzyme, 90 IU/mg protein, was actually lower than the 150 IU/mg protein observed for human G6PD. We conclude that G6PD after purification from the hemolysate of D. marsupialis does not have a high specific activity. Thus...

‣ Erythrocyte indices in the second trimester of pregnancy: are reference values well established?

Bresani,Cristiane C.; Souza,Ariani I.; Batista Filho,Malaquias
Fonte: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular Publicador: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2009 Português
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The erythrocyte index values in the pregnancy-puerperal cycle behave in a particular manner, however, the physiological or nosological meaning of such alterations are not well established. This study was aimed at analyzing the distribution of erythrocyte indices in the second trimester of pregnancy. The study was carried out with secondary data from 347 pregnant women in the 2nd trimester of low-risk prenatal care at the Instituto Materno Infantil Professor Fernando Figueira (Recife, Brazil) between May 2000 and June 2001. Measurements were performed using an automatic counter. Frequency distribution curves of erythrocyte indices (means and standard deviations) and correlation curves of hematocrit (HTC) and hemoglobin (Hb) concentrations were constructed. The mean red blood cell number (RBC) was 3.7 x 10(12)cells/L; mean HTC was 32.9% and mean Hb was 10.8 g/dL; the values exhibited Gaussian distributions. The mean morphological values were 88.4 fL for the mean corpuscular volume; 29.0 pg for the mean corpuscular hemoglobin and 32.8 g/dL for the mean corpuscular hemoglobin concentration; these values were not adjusted to Normal distributions. HTC values were three times higher than Hb values. Mean RBC, HTC and Hb values (used in the diagnosis of anemia) were lower than thresholds considered normal and exhibited Gaussian distributions. Morphological indices remained within normal ranges...

‣ Evaluation of erythrocyte and reticulocyte parameters as indicative of iron deficiency in patients with anemia of chronic disease

Torino,Ana Beatriz Barbosa; Gilberti,Maria de Fátima Pererira; Costa,Edvilson da; Lima,Gisélia Aparecida Freire de; Grotto,Helena Zerlotti Wolf
Fonte: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular Publicador: Associação Brasileira de Hematologia e Hemoterapia e Terapia Celular
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
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Objective: The aim of this study was to evaluate the effectiveness of mature red cell and reticulocyte parameters to identify three conditions: iron deficiency anemia, anemia of chronic disease, and anemia of chronic disease associated with absolute iron deficiency. Methods: Peripheral blood cells from 117 adult patients with anemia were classified accord- ing to iron status, inflammation, and hemoglobinopathies as: iron deficiency anemia (n = 42), anemia of chronic disease (n = 28), anemia of chronic disease associated with iron deficiency anemia (n = 22), and heterozygous β-thalassemia (n = 25). The percentage of microcytic eryth-rocytes, hypochromic erythrocytes, and the levels of hemoglobin in both reticulocytes and mature red cells were determined. Receiver operating characteristic analysis was used to evaluate the accuracy of the parameters in differentiating anemia. Results: There was no difference between the groups of iron deficiency and anemia of chronic disease associated with absolute iron deficiency for any of the parameters. The percentage of hypochromic erythrocytes was the best parameter to identify absolute iron deficiency in patients with anemia of chronic disease (area under curve = 0.785; 95% confidence interval: 0.661-0.909 with sensitivity of 72.7%...

‣ Glycophorin B is the Erythrocyte Receptor of Plasmodium Falciparum Erythrocyte-Binding Ligand, EBL-1

Mayer, D. C. Ghislaine; Cofie, Joann; Jiang, Lubin; Hartl, Daniel L.; Tracy, Erin; Kabat, Juraj; Mendoza, Laurence H.; Miller, Louis H.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
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In the war against Plasmodium, humans have evolved to eliminate or modify proteins on the erythrocyte surface that serve as receptors for parasite invasion, such as the Duffy blood group, a receptor for Plasmodium vivax, and the Gerbich-negative modification of glycophorin C for Plasmodium falciparum. In turn, the parasite counters with expansion and diversification of ligand families. The high degree of polymorphism in glycophorin B found in malaria-endemic regions suggests that it also may be a receptor for Plasmodium, but, to date, none has been identified. We provide evidence from erythrocyte-binding that glycophorin B is a receptor for the P. falciparum protein EBL-1, a member of the Duffy-binding-like erythrocyte-binding protein (DBL-EBP) receptor family. The erythrocyte-binding domain, region 2 of EBL-1, expressed on CHO-K1 cells, bound glycophorin B but not glycophorin B-null erythrocytes. In addition, glycophorin B but not glycophorin B-null erythrocytes adsorbed native EBL-1 from the P. falciparum culture supernatants. Interestingly, the Efe pygmies of the Ituri forest in the Democratic Republic of the Congo have the highest gene frequency of glycophorin B-null in the world, raising the possibility that the DBL-EBP family may have expanded in response to the high frequency of glycophorin B-null in the population.; Organismic and Evolutionary Biology

‣ Interação da miltefosina com os componentes lipídicos e proteicos das membranas de eritrócito e Leishmania estudada por ressonância paramagnética eletrônica; Interaction of miltefosine with the lipid and protein components of the erythrocyte and Leishmania membranes studied by electron paramagnetic resonance

Moreira, Rodrigo Alves
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Fisica (IF); Instituto de Física - IF (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Fisica (IF); Instituto de Física - IF (RG)
Tipo: Tese de Doutorado Formato: application/pdf
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Cutaneous leishmaniasis is a neglected tropical disease that infects millions of people worldwide, representing a serious public health problem. The miltefosine (MT) is an alkylphospholipid that has been approved for the treatment of breast cancer metastasis and visceral leishmaniasis, although the mechanism of action at the molecular level is poorly understood. Electron paramagnetic resonance (EPR) spectroscopy of the lipid spin lebel analog of stearic acid (5-DSA) and the maleimide derivative spin label (6-MSL) covalently bound to membrane proteins showed that the MT causes a large increase in the molecular dynamics of erythrocyte membranes (ghosts) and detergent resistant membranes (DRMs) prepared from erythrocyte membranes. In the vesicles of lipid raft constituents, it was shown that 20 mol% sphingomyelin could be replaced by 20 mol% MT with no change in the molecular dynamics. Furthermore, the effect of MT on DRMs was more pronounced than in erythrocyte ghosts, supporting the hypothesis that MT is a lipid raft modulator. At the reported MT-plasma concentrations found during the treatment of leishmaniasis (31-52μg/mL), our measurements in blood plasma indicated a hemolytic level of 2-5% and also showed that the MT concentration that changes the erythrocyte membrane fluidity to an extent that is detectable by EPR spectroscopy causes about 46% hemolysis. Subsequently...

‣ Cognitive performance in older adults is inversely associated with fish consumption but not erythrocyte membrane n-3 fatty acids

Danthiir, V.; Hosking, D.; Burns, N.; Wilson, C.; Nettelbeck, T.; Calvaresi, E.; Clifton, P.; Wittert, G.
Fonte: American Institute of Nutrition Publicador: American Institute of Nutrition
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
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Higher n–3 (ω-3) polyunsaturated fatty acids (PUFAs) and fish intake may help maintain cognitive function in older age. However, evidence is inconsistent; few studies have examined the relation in cognitively healthy individuals across numerous cognitive domains, and none to our knowledge have considered lifetime fish intake. We examined associations between multiple domains of cognition and erythrocyte membrane n–3 PUFA proportions and historical and contemporary fish intake in 390 normal older adults, analyzing baseline data from the Older People, Omega-3, and Cognitive Health trial. We measured n–3 PUFA in erythrocyte membranes, and we assessed historical and contemporary fish intake by food-frequency questionnaires. We assessed cognitive performance on reasoning, working memory, short-term memory, retrieval fluency, perceptual speed, simple/choice reaction time, speed of memory-scanning, reasoning speed, inhibition, and psychomotor speed. Cognitive outcomes for each construct were factor scores from confirmatory factor analysis. Multiple linear regression models controlled for a number of potential confounding factors, including age, education, sex, apolipoprotein E-ɛ 4 allele, physical activity, smoking, alcohol intake...

‣ Suicidal Erythrocyte Death in Malaria; Selbstmörderischer Erythrozytentod in der Malaria

Koka, Sai Sudha
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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Malaria is one of the most devastating diseases with lethal outcome in more than 1 million humans per year. The course of the disease is not only a function of the pathogen but is heavily influenced by properties of the host. Mechanisms possibly conferring protection against a severe course of malaria include suicidal death of the infected cell. A particular form of suicidal erythrocyte death is eryptosis, which is characterized by Ca2+-entry with subsequent activation of Ca2+-sensitive K+ channels, KCl exit and erythrocyte shrinkage, Ca2+-sensitive scrambling of phospholipids resulting in the breakdown of cell membrane phosphatidylserine asymmetry and phosphatidylserine exposure at the cell surface, as well as Ca2+ dependent activation of calpain, proteolytic degradation of cytoskeletal proteins and cell membrane blebbing. Eryptosis is triggered by different well-known pro apoptotic stressors, namely hyperosmotic shock, oxidative stress and energy depletion, which all activate Ca2+ -permeable nonselective cation channels allowing Ca2+ entry into the erythrocyte. Eryptosis is enhanced in several inherited erythrocyte disorders such as, phosphate depletion, hemolytic uremic syndrome, sepsis, and Wilson disease. As macrophages are equipped with receptors specific for phosphatidylserine...

‣ Receptors in the Regulation of Suicidal Erythrocyte death; Rezeptoren in der Regulation des suzidalen Erythrozytentodes

Mahmud, Hasan
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
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Eryptosis is characterized by cell shrinkage, cell membrane scrambling with subsequent exposure of phosphatidylserine at the erythrocyte surface. Activation of the erythrocytes Ca2+ permeable cation channel triggers suicidal erythrocyte death. Therefore eryptosis may contribute to physiological limitation of erythrocyte survival and there is strong evidence between excessive stimuli of eryptosis and the presence of clinical signs of anemia. Sepsis is paralleled by anemia, an effect resulting from eryptosis, the suicidal death of erythrocytes. Pathogen-induced eryptosis may partially result from interaction of bacterial cell wall components such as lipoproteins with the erythrocyte cell membrane. The first study explored, whether the synthetic lipopeptide Pam3CSK4 mimicking the acylated amino terminus of bacterial lipoproteins triggers eryptosis. According to annexin-V-binding in FACS analysis, Pam3CSK4 (1 myg/ml) stimulated phosphatidylserine exposure, an effect significantly blunted in the nominal absence of Ca2+. According to Fluo3 fluorescence, Pam3CSK4 increased cytosolic Ca2+ activity and moderately stimulated erythrocytic ceramide formation, both are considered to be major triggers of eryptosis. In conclusion, bacterial lipoproteins participate in the stimulation of erythrocyte cell membrane scrambling by bacterial cell wall components. Thus...

‣ The phylogenetic odyssey of the erythrocyte. IV. The amphibians

Glomski, Chester A.; Tamburlin, Judith; Hard, R.; Chainani, Meena
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
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Amphibians manifest permanently nucleated, oval, flattened, biconvex erythrocytes. These cells demonstrate a cytoskeleton which is responsible for their morphogenetic conversion from a sphere to an ellipse and imparts to their cellular mass reversibility of traumatic deformation. The class Amphibia has the largest of al1 erythrocytes attaining volumes greater than 10,000 femtoliters in the Amphiuma. The large dimensions reflect evolutionary processes, genomic size, ploidy and the relative size of other somatic cells. Conversely, the erythrocyte count and hemoglobin concentration of these species are low. Occasional denucleated red cells can be seen in the peripheral blood but may attain levels of 90-95% of the total circulating population in certain members of the tribe Bolitoglossini (e.g. Batrachoseps attenuatus). These erythroplastids retain the marginal band thus remaining different from mammalian erythrocytes. Embryologically, erythropoiesis initiates in the yolk sac and then progreses to the kidney, liver, and possibly spleen. The yolk sac cohort is transitory and is successively replaced by the larval and definitive populations of erythrocytes. Red cell production (along with thrombocytopoiesis) in adult urodeles is conducted intravascularly in the spleen. In anurans this organ is usually the major site although the liver also serves as a secondary locus for this activity. Medullary (bone marrow) erythropoiesis makes its phylogenetic debut in anurans and typically occurs during heightened hemopoiesis following metamorphosis or hibernation. Maturation of the erythrocyte in the circulation is commonplace (especially in urodeles) while proliferation at this site is inducible by splenectomy andlor hemolysins. Erythrocyte-related values demonstrate variable differences associated with age...

‣ Modulation of erythrocyte hemorheological properties by band 3 phosphorylation and dephosphorylation

Saldanha, Carlota; Silva, Ana S.; Gonçalves, Sónia; Martins-Silva, João
Fonte: IOS Press Publicador: IOS Press
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
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© 2007 – IOS Press and the authors. All rights reserved; The objective of the present work was to study the effects of erythrocyte proteins phosphorylation in erythrocyte aggregation and deformability. Human whole blood samples were incubated in vitro in absent and in presence of the phosphorylation/dephosphorilation band 3 inhibitors and also with adenylyl cyclase, guanylate cyclase and PI3K inhibitors and the erythrocyte aggregation index (EAI) and deformability were assayed. The results show that when band 3 is phosphorylated in presence of a PTP inhibitor an increase in erythrocyte aggregation index is observed (p < 0.0001). A partial dephosphorylation band 3 state, induced by PTK inhibitors, show a decrease in the erythrocyte aggregation index (p < 0.002). However both manipulated states induced lower EAI values than blood samples aliquots controls. The guanylate cyclase and PI3-K inhibitors significantly decrease the erythrocyte aggregation index in relation with the control blood samples. Erythrocyte deformability in presence of all the inhibitors did not showed significant changes. PTP and PI3-K inhibitors showed a significantly increase in the plasma potassium concentrations not associated with EAI values. Methehemoglobin levels were increased significantly when guanylate cyclase inhibitor is present in the blood samples. In conclusion...

‣ The phylogenetic odyssey of the erythrocyte. III. Fish, the lower vertebrate experience

Glomski, Chester A.; Tamburlin, Judith; Chainani, Meena
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
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The piscine erythrocyte can be considered the prototype of the red cells that are distributed among inframmalian vertebrates. It is a permanently nucleated, hemoglobin-ladened, oval, flattened, biconvex disc. Ultrastructurally it demonstrates a cytoskeleton comprised of a marginal band and a membrane skeleton which are responsible for the erythrocyte's conversion to an ellipsoid during morphogenesis and endow it with resilience to physical trauma. Erythropoiesis initiates in the yolk sac, followed in many fishes, by the intermediate cell mass. These sites are the sources of the transitory, primitive generation red cells which apparently make their first phylogenetic appearance in fishes and which are subsequently represented in al1 classes of vertebrates including mammals. Production of definitive generation erythrocytes is centered in evolutionary «pre-splenic» tissue of the gastrointestinal tract or in the spleen in cyclostomes, dipnoi, and chondrichthyes while in teleosts it is typically located in the kidneys with or without splenic participation. The blood is a major site of erythrocyte maturation in the lower fishes and exhibits significant numbers of immature erythroid cells plus occasional mitotic figures. Some teleosts also circulate developing erythroid cells. Certain fishes have occasional circulating erythroplastids...

‣ Microplate reader analysis of triatomine saliva effect on erythrocyte aggregation

Cardoso,Antonio Valadão; Pereira,Marcos Horácio; Marcondes,Guilherme de Araújo; Ferreira,Adriana Rosa; Araújo,Patrícia Rosa de
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2007 Português
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Our hypothesis is that the action of aggregating and disaggregating substances in the blood can be detected and quantified by the Microplate Reader. To ascertain the validity of this hypothesis, we selected two types of blood: one that naturally presents erythrocyte aggregation (pig blood) and the other that does not present aggregation (bovine blood). One important reason for the choice of pig blood is that its erythrocyte aggregation resembles that of human blood. T. infestans saliva was added to the pig blood as a disaggregating substance, while bovine fibrinogen was added to the bovine blood as a substance that promotes erythrocyte aggregation. We investigated the dynamic viscosity (h) of these mammals' blood, of T. infestans saliva and of the absorption (A) by Microplate Reader, carrying out UV-Vis spectrophotometric assays of pig plasma with different concentrations of triatominae saliva and of bovine blood with different concentrations of fibrinogen. Our findings indicate that spectroscopic techniques such as the Microplate Reader complement and expand the study of blood rheology, erythrocyte sedimentation and aggregation.

‣ Intraspecific variation in erythrocyte sizes among populations of Hypsiboas cordobae (Anura, Hylidae).

Baraquet, Mariana; Grenat, Pablo Raúl; Salas, Nancy Edith; Martino, Adolfo Ludovico
Fonte: Firenze University Press Publicador: Firenze University Press
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
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We studied the morphology and size of erythrocytes of H. cordobae, and analysed the geographic variation of this character along the distribution of the species, in relation to the latitudinal and altitudinal distances. Erythrocyte shape of the H. cordobae is ellipsoidal and the nuclei are also ellipsoidal and centrally oriented. Erythrocyte and nuclear size showed significant differences among populations, with the highest mean size corresponding to the population of Achiras (low altitude site) and the lowest mean size to Los Linderos (high altitude site). There was no significant relationship between the latitude of each population and the both erythrocyte and nuclear size. The altitudinal variation in erythrocyte cell size may be attributable to the surface available for gas exchange; a small erythrocyte offers a possibility of greater rate of exchange than a larger one. Our results are consistent with studies of other amphibians, where intraspecific comparisons of populations at different altitudes show that individuals at higher altitudes are characterized by smaller erythrocytes.; Fil: Baraquet, Mariana. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Ecología; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba; Argentina;; Fil: Grenat...