RESUMO
The toxicological impact of airborne polluting ultrafine particles (UFPs, also classified as nanoparticles with average sizes of less than 100 nm) is an emerging area of research pursuing a better understanding of the health hazards they pose to humans and other organisms. Hemolytic activity is a toxicity parameter that can be assessed quickly and easily to establish part of a nanoparticle's behavior once it reaches our circulatory system. However, it is exceedingly difficult to determine to what extent each of the nanoparticles present in the air is responsible for the detrimental effects exhibited. At the same time, current hemolytic assessment methodologies pose a series of limitations for the interpretation of results. An alternative is to synthesize nanoparticles that model selected typical types of UFPs in air pollution and evaluate their individual contributions to adverse health effects under a clinical assay of osmotic fragility. Here, we discuss evidence pointing out that the absence of hemolysis is not always a synonym for safety; exposure to model nanopollutants, even at low concentrations, is enough to increase erythrocyte susceptibility and dysfunction. A modified osmotic fragility assay in combination with a morphological inspection of the nanopollutant-erythrocyte interaction allows a richer interpretation of the exposure outcomes. Membrane-nanoparticle interplay has a leading role in the vulnerability observed. Therefore, future research in this line of work should pay special attention to the evaluation of the mechanisms that cause membrane damage.
RESUMO
Epirubicin is a cytotoxic drug used in the treatment of different types of cancer and increasing evidence suggests that its target is cell membranes. In order to gain insight on its toxic effects, intact red blood cells (RBC), human erythrocyte membranes and molecular models were used. The latter consisted in bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), phospholipid classes found mainly in the outer and inner monolayers of the human erythrocyte membrane, respectively. The results obtained by X-ray diffraction displayed that epirubicin induced structural perturbations in multilayers of DMPC. Differential scanning calorimetry (DSC) showed that epirubicin disturbed the thermotropic behavior of both DMPC and DMPE vesicles, whereas fluorescence spectroscopy demonstrated alterations in the fluidity of DMPC vesicles and the erythrocyte membrane. Scanning electron microscopy (SEM) revealed that epirubicin changed the normal discoid form of RBC to echinocytes and stomatocytes. Electron paramagnetic resonance (EPR) disclosed that this drug induced conformational changes in the erythrocyte membrane proteins. These findings demonstrate that epirubicin interacts with lipids and proteins of the human erythrocyte membrane, effects that might compromise the integrity and function of cell membranes. This is the first time that its toxic effects on the human erythrocyte membrane have been described.
Assuntos
Antibióticos Antineoplásicos/toxicidade , Epirubicina/toxicidade , Eritrócitos/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Células Cultivadas , Dimiristoilfosfatidilcolina , Eritrócitos/patologia , Eritrócitos/ultraestrutura , Humanos , Lipossomos , Microscopia Eletrônica de Varredura , Fosfatidiletanolaminas , Difração de Raios XRESUMO
Hydroxyurea (HU) is used as a therapy in sickle cell anemia (SCA). Many studies have established that HU improves patient quality of life by reducing symptoms. However, the effect of HU on erythrocytes is not well-described. We evaluated several parameters related to oxidative stress and total lipid content of erythrocytes in patients with SCA. The patient cohort consisted of 7 SCA patients treated with HU, 17 untreated SCA patients, and 15 healthy subjects. Erythrocytes from patients with SCA displayed increased oxidative stress relative to the control group, including higher thiobarbituric acid reactive substances (TBARS), Fe3+ content, and osmotic fragility, and decreased total cholesterol. We observed that treatment of SCA patients with HU increased Fe3+ content and activity of glutathione peroxidase, and decreased glutathione reductase activity, glutathione levels, total cholesterol, and phospholipid content comaperaded to patients untreated with HU. Thus, HU alters biochemical characteristics of erythrocytes; future studies will determine whether they are beneficial or not.
Assuntos
Anemia Falciforme , Eritrócitos Anormais/metabolismo , Hidroxiureia/administração & dosagem , Estresse Oxidativo/efeitos dos fármacos , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/tratamento farmacológico , Colesterol/sangue , Feminino , Humanos , Masculino , Fragilidade Osmótica/efeitos dos fármacos , Fosfolipídeos/sangue , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Introducción: la malaria es uno de los mayores retos de la salud pública mundial. Es causada principalmente por los parásitos Plasmodium falciparum y Plasmodium vivax. Durante el proceso de invasión, se encuentran involucra-das las proteínas homólogas de unión a reticulocitos de P.falciparumPfRH1, PfRH2a, PfRH2b, PfRH4 y PfRH5, que tras su unión a receptores específicos de membrana permiten la invasión del merozoíto al eritrocito. Objetivo: compilar y resumir las características moleculares y estructurales de las interacciones entre las proteínas pertenecientes a la familia de proteínas homólogas de unión a reticulocitos de P.falciparum y los receptores expre-sados en la célula del hospedero. Método: revisión descriptiva sobre las proteínas homólogas de unión a reticulocitos de P. falciparum involucradas en el proceso de invasión al eritrocito. Esta revisiónincluye literatura publicada hasta el año 2020 en bases de datos electrónicas especializadas en investigación biomédica. Se encontraron 105 documentos, de los cuales se se-leccionaron 70 y se excluyeron 11, por no presentar los criterios de inclusión, analizando un total de 59 referencias. Conclusión: la invasión del merozoíto es mediada por interacciones específicas de los ligandos de las familias EBL y PfRH. La unión de las proteínas PfRH1 y PfRH2b a sus receptores en el eritrocito da lugar a la liberación de la proteína EBL-175 que, junto con PfRH4, median la formación de una unión estrecha entre el parásito y los glóbulos rojos. Ello permite la unión de la proteína PfRH5 a la basigina y la entrada del parásito a la célula del hospedero
Introduction: Malaria is one of the world's greatest public health challenges, caused mainly by Plas-modium falciparum and Plasmodium vivax. During the invasion process, the P. falciparum reticulo-cyte-binding homologous proteins PfRH1, PfRH2a, PfRH2b, PfRH4 and PfRH5 are involved, which after binding to specific membrane receptors allow the invasion of the merozoite into the erythrocyte. Objective: To compile and summarize the molecular and structural characteristics of the interactions between proteins belonging to the P. falciparum family of reticulocyte-binding homologous proteins and the receptors expressed in the host cell. Method: Descriptive review of the P. falciparum reticulocyte-binding homologous proteins involved in the process of erythrocyte invasion. This review includes literature published until 2020 in electronic databases specialized in biomedical research. We found 105 papers, of which 70 were selected and 11 were excluded for not presenting the inclusion criteria, analyzing a total of 59 references. Conclusion: The invasion of merozoite is mediated by specific interactions of the ligands of the LBS and PfRH families. The binding of the PfRH1 and PfRH2b proteins to their receptors in the erythrocyte results in the release of the EBL-175 protein, which together with PfRH4 mediates the formation of a close bond between the parasite and the red blood cells, thus allowing the binding of the PfRH5 protein to basigin and the entry of the parasite into the host cell.
Introdução: a malária é um dos maiores desafios globais de saúde pública. É causada principalmente pelos parasitas Plasmodium falciparum e Plasmodium vivax. Durante o processo de invasão, proteínas homólogas de ligação a reticulócitos de P. falciparum PfRH1, PfRH2a, PfRH2b, PfRH4 e PfRH5 estão envolvidas, que após a ligação a receptores de membrana específicos permitem a invasão do mero-zoíta ao andritro. Objetivo: compilar e resumir as características moleculares e estruturais das interações entre as pro-teínas pertencentes à família das proteínas reticulocitárias homólogas de P. falciparum e os receptores expressos na célula hospedeira. Método: revisão descritiva das proteínas ho-mólogas de ligação a reticulócitos de P. falciparum envol-vidas no processo de invasão eritrocitária. Esta revisão inclui literatura publicada até 2020 em bases de dados eletrônicas especializadas em pesquisa biomédica. Foram encontrados 105 documentos, dos quais 70 foram selecionados e 11 excluídos por não apresentarem os critérios de inclusão, anali-sando um total de 59 referências. Conclusão: a invasão de merozoítos é mediada por interações específicas dos ligantes das famílias EBL e PfRH. A ligação das proteínas PfRH1 e PfRH2b aos seus receptores no eritrócito resulta na libe-ração da prote-ína EBL-175 que, junto com PfRH4, a mediação da formação de uma junção compacta entre o parasita e as hemácias. Isso permite a ligação da proteína PfRH5 à basigina e a entrada do parasita na célula hospedeira.
Assuntos
Malária , Plasmodium falciparum , Membrana Eritrocítica , Eritrócitos , LigantesRESUMO
Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which can cause lipid changes in the erythrocyte membrane. Optical tweezers were used to characterize rheological changes in erythrocytes from patients with leptospirosis in the late stage. Biochemical methods were also used for quantification of plasma lipid, erythrocyte membrane lipid, and evaluation of liver function. Our data showed that the mean elastic constant of erythrocytes from patients with leptospirosis was around 67% higher than the control (healthy individuals), indicating that patient's erythrocytes were less elastic. In individuals with leptospirosis, several alterations in relation to control were observed in the plasma lipids, however, in the erythrocyte membrane, only phosphatidylcholine showed a significant difference compared to control, increasing around 41%. With respect to the evaluation of liver function of individuals with leptospirosis, there was a significant increase in levels of alanine transaminase (154%) and aspartate transaminase (150%), whereas albumin was 43.8% lower than control (P<0.01). The lecithin-cholesterol acyltransferase fractional activity was 3.6 times lower in individuals with leptospirosis than in the healthy individuals (P<0.01). The decrease of the erythrocyte elasticity may be related to the changes of erythrocyte membrane phospholipids composition caused by disturbances that occur during human leptospirosis, with phosphatidylcholine being a strong candidate in the erythrocyte rheological changes.
Assuntos
Humanos , Eritrócitos , Leptospirose , Fosfolipídeos , Membrana Eritrocítica , Lipídeos de MembranaRESUMO
The human red blood cell (RBC) membrane has significant elastic capabilities which can be described measuring typical membrane edge fluctuations and mechanical properties by optical techniques. The RBC elastic properties can be affected by changes in the surrounding media. In an attempt to elucidate the molecular mechanisms of the interaction of resveratrol with the red cell membrane and of its antioxidant capacity the changes in mechanical properties of the RBC membrane were analyzed. These studies were carried out through measurements of RBC membrane fluctuations in the presence of the oxidant agent HClO using thermal fluctuation spectroscopy (TFS). The observed results showed that the elastic capabilities of RBC changed with low concentration of hypochlorous acid but without morphological changes. However, in the presence of resveratrol the deformation and decrease of elastic capabilities induced by HClO on RBC decreased. These in vitro results demonstrated the protective effect of RV against the detrimental effects triggered by HClO upon human erythrocytes.
Assuntos
Antioxidantes/metabolismo , Eritrócitos/metabolismo , Resveratrol/sangue , Análise Espectral/métodos , Membrana Eritrocítica/metabolismo , Humanos , Ácido Hipocloroso/metabolismo , Análise de Célula ÚnicaRESUMO
The interactions and the protective effect of epigallocatechin gallate (EGCG) on human erythrocytes (RBC) and molecular models of its membrane were investigated. The latter consisted of bilayers built- up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. X-ray diffraction and differential scanning calorimetry experiments showed that EGCG induced significant structural and thermotropic perturbations in multilayers and vesicles of DMPC; however, these effects were not observed in DMPE. Fluorescence spectroscopy results revealed that EGCG produced alterations of the molecular dynamics at the level of the hydrophobic-hydrophilic interface in DMPC vesicles, and in isolated unsealed human erythrocyte membranes (IUM). EGCG also induced morphological alterations in RBC from their normal discoid form to echinocytes. These outcomes indicate that EGCG molecules were located in the outer monolayer of the erythrocyte membrane. The assessment of EGCG protective effect demonstrated that it inhibits the morphological alterations and lysis induced by HClO to human erythrocytes. The results obtained from this study suggest that the insertion of EGCG into the outer monolayer of the erythrocyte membrane might prevent the access and deleterious effects of oxidant molecules such as HClO and free radicals into the red cells, protecting them from oxidative damage.
Assuntos
Antioxidantes/farmacologia , Catequina/análogos & derivados , Membrana Eritrocítica/efeitos dos fármacos , Ácido Hipocloroso/antagonistas & inibidores , Oxidantes/antagonistas & inibidores , Antioxidantes/química , Catequina/química , Catequina/farmacologia , Dimiristoilfosfatidilcolina/química , Membrana Eritrocítica/química , Hemólise/efeitos dos fármacos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ácido Hipocloroso/farmacologia , Cinética , Bicamadas Lipídicas/química , Oxidantes/farmacologia , Fosfatidiletanolaminas/química , Espectrometria de Fluorescência , TermodinâmicaRESUMO
The interaction and protective effect of caffeic acid (CA) on human erythrocytes (RBC) and molecular models of its membrane were studied. The latter consisted of bilayers built up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. X-ray diffraction and differential scanning calorimetry results indicated that CA induced structural and thermotropic perturbations in multilayers and vesicles of DMPC. Fluorescence spectroscopy analysis showed that CA increased the fluidity of DMPC vesicles and of human erythrocyte ghosts. Scanning electron microscopy observations displayed that CA induced morphological alterations to RBC from their normal discoid form to echinocytes. The assessment of its protective capacity showed that CA inhibits RBC morphological alterations and lysis induced by HClO. These findings imply that CA molecules were located in the outer monolayer of the erythrocyte membrane, and that this preferential location might effectively protect the red cells from damage caused by oxidizing species.
Assuntos
Ácidos Cafeicos/farmacologia , Eritrócitos/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina/metabolismo , Eritrócitos/metabolismo , Glicerofosfolipídeos/metabolismo , Hemólise/efeitos dos fármacos , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Espectrometria de Fluorescência , Difração de Raios XRESUMO
Detergents are amphiphilic molecules widely used to solubilize biological membranes and/or extract their components. Nevertheless, because of the complex composition of biomembranes, their solubilization by detergents has not been systematically studied. In this review, we address the solubilization of erythrocytes, which provide a relatively simple, robust and easy to handle biomembrane, and of biomimetic models, to stress the role of the lipid composition on the solubilization process. First, results of a systematic study on the solubilization of human erythrocyte membranes by different series of non-ionic (Triton, CxEy, Brij, Renex, Tween), anionic (bile salts) and zwitterionic (ASB, CHAPS) detergents are shown. Such quantitative approach allowed us to propose Resat-the effective detergent/lipid molar ratio in the membrane for the onset of hemolysis as a new parameter to classify the solubilization efficiency of detergents. Second, detergent-resistant membranes (DRMs) obtained as a result of the partial solubilization of erythrocytes by TX-100, C12E8 and Brij detergents are examined. DRMs were characterized by their cholesterol, sphingolipid and specific proteins content, as well as lipid packing. Finally, lipid bilayers of tuned lipid composition forming liposomes were used to investigate the solubilization process of membranes of different compositions/phases induced by Triton X-100. Optical microscopy of giant unilamellar vesicles revealed that pure phospholipid membranes are fully solubilized, whereas the presence of cholesterol renders the mixture partially or even fully insoluble, depending on the composition. Additionally, Triton X-100 induced phase separation in raft-like mixtures, and selective solubilization of the fluid phase only.
RESUMO
Thimerosal (THI, ethyl-mercury thiosalicylate) is added to vaccines as a preservative; as a consequence, infants may have been exposed to bolus doses of Hg that collectively added up to nominally 200 µg Hg during the first 6 months of life. While several studies report an association between THI-containing vaccines and neurological disorders, other studies do not support the causal relation between THI and autism. With the purpose to understand the molecular mechanisms of the toxic effect of THI it was assayed on human red cells and in bilayers built-up of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), classes of phospholipids found in the outer and inner monolayers of the human erythrocyte membrane, respectively. The capacity of THI to interact with DMPC and DMPE was determined by X-ray diffraction and differential scanning calorimetry, whereas intact human erythrocytes were observed by optical, defocusing and scanning electron microscopy. The experimental findings of this study demonstrated that THI interacted in a concentration-dependent manner with DMPC and DMPE bilayers, and in vitro interacted with erythrocytes inducing morphological changes. However, concentrations were considerable higher than those present in vaccines.
Assuntos
Eritrócitos/efeitos dos fármacos , Bicamadas Lipídicas , Timerosal/farmacologia , Varredura Diferencial de Calorimetria , Células Cultivadas , Dimiristoilfosfatidilcolina/química , Membrana Eritrocítica/química , Membrana Eritrocítica/efeitos dos fármacos , Eritrócitos/ultraestrutura , Humanos , Bicamadas Lipídicas/química , Lipossomos , Estrutura Molecular , Fosfatidiletanolaminas/química , Conservantes Farmacêuticos/farmacologia , Termodinâmica , Timerosal/química , Difração de Raios XRESUMO
Gallic acid (GA) is a polyphenol present in many plants. This study was aimed to investigate the molecular interaction of GA with the human erythrocyte membrane and to determine its antioxidant capacity. The molecular interaction with the membrane of human red cells and the antioxidant property was assayed on both human red cells and molecular models of its membrane. Observations by optical, scanning electron, and defocusing microscopy demonstrated that GA is capable to convert red cells from their normal biconcave shape to crenated echinocytes. This result indicates that GA molecules are positioned in the outer monolayer of the red cell membrane. Dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were selected as classes of phospholipids found in the outer and inner monolayers of the red cell membrane, respectively. X-ray diffraction and differential scanning calorimetry showed that GA was preferentially bound to DMPC bilayers. Experiments related to the antioxidant capacity of GA indicated that this compound offsets HClO oxidative capacity on DMPE bilayers. In addition, optical, scanning, defocusing microscopy, and hemolysis assays confirmed the protective capacity of GA against HClO deleterious effects on human red cells. As a conclusion, GA would be capable to block the access of oxidants into the lipid bilayer, and thus avoid their access into red cells.
Assuntos
Antioxidantes/farmacologia , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Ácido Gálico/farmacologia , Antioxidantes/química , Varredura Diferencial de Calorimetria , Células Cultivadas , Membrana Eritrocítica/efeitos dos fármacos , Membrana Eritrocítica/metabolismo , Eritrócitos/ultraestrutura , Ácido Gálico/química , Hemólise/efeitos dos fármacos , Humanos , Bicamadas Lipídicas , Estrutura Molecular , Fosfolipídeos , Termodinâmica , Difração de Raios XRESUMO
In order to gain insight into the molecular mechanism of the antioxidant properties of Solanum crispum, aqueous extracts of its leaves were assayed on human erythrocytes and molecular models of its membrane. Phenolics and alkaloids were detected by HPLC-MS. Scanning electron and defocusing microscopy showed that S. crispum changed erythrocytes from the normal shape to echinocytes. These results imply that molecules present in the aqueous extracts were located in the outer monolayer of the erythrocyte membrane. Dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) were chosen as representative of phospholipid classes located in the outer and inner monolayers of the erythrocyte membrane, respectively. X-ray diffraction showed that S. crispum preferentially interacted with DMPC bilayers. Experiments regarding its antioxidant properties showed that S. crispum neutralized the oxidative capacity of HClO on DMPE bilayers; defocusing microscopy and hemolysis assays demonstrated the protective effect of S. crispum against the oxidant effects of HClO on human erythrocytes.
Assuntos
Antioxidantes/farmacologia , Eritrócitos/efeitos dos fármacos , Eritrócitos/metabolismo , Extratos Vegetais/farmacologia , Solanum/química , Cromatografia Líquida de Alta Pressão , Eritrócitos/citologia , Eritrócitos/ultraestrutura , Hemólise/efeitos dos fármacos , Humanos , Bicamadas Lipídicas , Espectrometria de Massas , Extratos Vegetais/química , Polifenóis/química , Polifenóis/farmacologia , Difração de Raios XRESUMO
Despite more than 300 theories to explain the aging process, oxidative stress theory offers the best mechanism to explain aging and age related disorders. Several studies has shown the importance of oxidative stress during aging. PubMed, Science Direct and Springer online data bases are taken into consideration to write this mini-review. Human erythrocytes are most abundant and specialized cells in the body. Erythrocytes were extensively studied due to their metabolism and gas transport functions. Recent studies on erythrocytes have provided us detailed information of cell membrane and its structural organization that may help in studying the aging and age associated changes. The susceptibility of an organism is associated with the antioxidant potential of the body. Erythrocytes have potent antioxidant protection consisting of enzymatic and non-enzymatic pathways that counteract with reactive oxygen species, thus maintaining the redox regulation in the body. The non-enzymatic and enzymatic antioxidants and other biomarkers associated with erythrocyte membrane transport functions are the main content of this review. Biomarkers of oxidative stress in erythrocytes and its membrane were taken into the consideration during human aging that will be the main subject of this mini- review.
RESUMO
Resveratrol (RV) is a potent antioxidant, anticancer and anti-inflammatory agent. Its main target of action is the cell membrane; however, its effect on that of human erythrocytes has been scarcely investigated. With the aim to better understand the molecular mechanisms of the interaction of RV with cell membranes both human erythrocytes and molecular models of its membrane have been utilized. The latter consisted in bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the erythrocyte membrane, respectively. Results by X-ray diffraction showed that RV produced a significant structural perturbation on DMPC bilayers, but no effects were observed in DMPE. Scanning electron (SEM) and defocusing microscopy (DM) observations showed that RV induced morphological alterations to the red cells from the normal discoid shape to echinocytes. These results imply that RV was located in the outer monolayer of the erythrocyte membrane. Results of its antioxidant properties showed that RV neutralized the oxidative capacity of HClO on DMPC and DMPE bilayers. On the other hand, SEM and DM observations as well as hemolysis assays demonstrated the protective effect of RV against the deleterious effects of HClO upon human erythrocytes.
Assuntos
Eritrócitos/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Estilbenos/farmacologia , Antioxidantes/química , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Dimiristoilfosfatidilcolina/química , Dimiristoilfosfatidilcolina/metabolismo , Relação Dose-Resposta a Droga , Membrana Eritrocítica/química , Membrana Eritrocítica/metabolismo , Eritrócitos/metabolismo , Eritrócitos/ultraestrutura , Humanos , Ácido Hipocloroso/farmacologia , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Microscopia/métodos , Microscopia Eletrônica de Varredura , Estrutura Molecular , Oxidantes/farmacologia , Fosfatidiletanolaminas/química , Fosfatidiletanolaminas/metabolismo , Substâncias Protetoras/química , Substâncias Protetoras/metabolismo , Substâncias Protetoras/farmacologia , Resveratrol , Estilbenos/química , Estilbenos/metabolismo , Difração de Raios XRESUMO
This report presents evidence that the following Solanum steroids: solasodine, diosgenin and solanine interact with human erythrocytes and molecular models of their membranes as follows: a) X-ray diffraction studies showed that the compounds at low molar ratios (0.1-10.0mol%) induced increasing structural perturbation to dimyristoylphosphatidylcholine bilayers and to a considerable lower extent to those of dimyristoylphosphatidylethanolamine; b) differential scanning calorimetry data showed that the compounds were able to alter the cooperativity of dimyristoylphosphatidylcholine, dimyristoylphosphatidylethanolamine and dimyristoylphosphatidylserine phase transitions in a concentration-dependent manner; c) in the presence of steroids, the fluorescence of Merocyanine 540 incorporated to the membranes decreased suggesting a fluidization of the lipid system; d) scanning electron microscopy observations showed that all steroids altered the normal shape of human erythrocytes inducing mainly echinocytosis, characterized by the formation of blebs in their surfaces, an indication that their molecules are located into the outer monolayer of the erythrocyte membrane.
Assuntos
Diosgenina/química , Membrana Eritrocítica/química , Bicamadas Lipídicas/química , Alcaloides de Solanáceas/química , Solanina/química , Varredura Diferencial de Calorimetria , Dimiristoilfosfatidilcolina/química , Diosgenina/farmacologia , Membrana Eritrocítica/efeitos dos fármacos , Corantes Fluorescentes/química , Humanos , Microscopia Eletrônica de Varredura , Transição de Fase/efeitos dos fármacos , Fosfatidiletanolaminas/química , Fosfatidilserinas/química , Pirimidinonas/química , Espalhamento a Baixo Ângulo , Alcaloides de Solanáceas/farmacologia , Solanina/farmacologia , Difração de Raios XRESUMO
La esferocitosis hereditaria es la anemia hemolítica congénita más frecuente en la población caucásica. Tiene una amplia variabilidad clínica y desde el punto de vista hematológico se caracteriza por anemia y presencia de esferocitos en la lámina periférica. Su base fisiopatológica está determinada por el defecto de algunas de las proteínas que conforman la membrana eritrocitaria, por el efecto del bazo sobre los hematíes anómalos y otros factores. A la luz de los conocimientos actuales, la interpretación dinámica del proceso requiere adentrarse en los estadios iniciales de la hematopoyesis, pues desde etapas tan tempranas como la enucleación del eritroblasto en la formación del reticulocito, hasta posibles procesos inflamatorios tardíos, pudieran modular la expresión de la enfermedad. Se hace una revisión de las características estructurales y funcionales de la membrana eritrocitaria, así como algunos aspectos generales de las propiedades del hematíe para facilitar la comprensión de los eventos que tienen lugar a partir del compromiso molecular de las proteínas que conforman la membrana
Hereditary spherocytosis is the most common congenital hemolytic anemia among Caucasian population. It has wide clinical variety and from the haematological point of view, it is characterized by the presence of spherocytes anemia in peripheral lamina. Its pathophysiological defect is determined by some of the proteins that make up the red cell membrane due to the effect on erythrocytes of abnormal spleen, and other factors. In view of current knowledge, the dynamic interpretation of this process requires delving into the early stages of hematopoiesis, since the expression of this disease could modulate from early stages of erythroblast enucleation in reticulocyte formation until late potential inflammatory processes. A review was made on the structural and functional characteristics of the erythrocyte membrane, as well as some general aspects of the properties of the red cell to facilitate understanding of events which take place through proteins molecular involvement forming the membrane
Assuntos
Humanos , Masculino , Feminino , Esferocitose Hereditária/epidemiologia , Esferocitose Hereditária/fisiopatologia , Esferocitose Hereditária/genética , Proteínas de Membrana/uso terapêuticoRESUMO
Se realizó un estudio hematológico, bioquímico y clínico a 6 pacientes diagnosticados con esferocitosis hereditaria (HS) y a sus familiares (40). Se encontraron 13 familiares portadores de la enfermedad. En 4 familias, el patrón de herencia fue autosómico dominante y en 2 de ellas no se pudo precisar. Los 19 casos se clasificaron en: 6 (31,6 %) portadores asintomáticos, 2 (10,5 %) con esferocitosis hereditaria ligera, 9 (47,4 %) con la forma típica y 2 (10,5 %) con la forma severa. Diez (52,6 %) tenían defecto de espectrina, de ellos, 6 (31,5 %) con otra alteración asociada. En 8 (42,1 %) no se pudo precisar el defecto bioquímico. No observamos relación entre la alteración bioquímica y el cuadro clínico de la enfermedad. La expresión hematológica, bioquímica y clínica fue muy heterogénea entre las diferentes familias y entre los miembros afectados de cada una de ellas. La alteración bioquímica más frecuente fue la deficiencia de espectrina. Nuestros resultados son similares a los señalados por otros investigadores.
A hematologic, biochemical and clinical study was conducted in 6 patients diagnosed with inheritable spherocytosis (IS) and its relatives (40). There were 40 family carriers of this disease. In 4 family, the inheritance pattern was autosomal dominant, and in two of them it was impossible its determination. The 19 cases were classified in: 6 (31,6%) asymptomatic carriers,2 (10,5%) with light-inheritable spherocytosis, 9 (47,4%) con the typical presentation, and 2 (10,5%) with the severe presentation. Ten (52,6%) had spectrine defect , from them, 6 (31,5%) with another associated alteration. In 8 (42,1%) it was impossible to determine the biochemical defect. There was not relation between biochemical alteration and the clinical picture of this disease. Hematologic, biochemical and clinical expression was very heterogeneous among the different families and among the members affected of each. The more frequent biochemical alteration was the spectrine deficiency. Our results are similar to reported by other researchers.
RESUMO
Os antígenos de grupos sanguíneos eritrocitários são estruturas macromoleculares localizadas na superfície extracelular da membrana eritrocitária. Com o desenvolvimento de estudos moleculares, mais de 250 antígenos são conhecidos e estão organizados em 29 sistemas de grupos sanguíneos reconhecidos pela Sociedade Internacional de Transfusão Sanguínea (ISBT). Estudos têm revelado que os antígenos de grupo sanguíneo estão expressos na membrana eritrocitária com ampla diversidade estrutural, incluindo epítopos de carboidratos em glicoproteínas e/ou glicolipídios e em proteínas inseridas na membrana via um domínio, via domínios de multipassagem ou ligados a glicosilfosfatidinositol. Além das diversidades estruturais, muitas funções importantes têm sido associadas aos antígenos eritrocitários recentemente identificadas, podendo ser esquematicamente divididas em: estruturais, transportadores, receptores e moléculas de adesão, enzimas, proteínas controladoras do complemento e outras. Esta revisão tem como foco as funções potenciais das moléculas que expressam os antígenos eritrocitários.
Erythrocyte blood group antigens are macromolecules structures located on the extracellular surface of the red blood cell membrane. The development of molecular studies allowed the recognition of more than 250 antigens by the International Society for Blood Transfusion (ISBT). These studies have also shown that blood group antigens are carried on red blood cell membrane of wide structural diversity, including carbohydrate epitopes on glycoproteins and/or glycolipids and on proteins inserted within the membrane via single or multi-pass transmembrane domains, or via glycosylphosphatidylinositol linkages. In addition, to their structural diversity, many important functions associated with blood group antigens have been recently identified and can be didactically divided into: structural proteins, transporters, receptors and adhesion molecules, enzymes, complement control proteins and others. This review will focus on the potential functions of the molecules that express blood group antigens.
Assuntos
Humanos , Antígenos de Grupos Sanguíneos , Sistema do Grupo Sanguíneo Rh-HrRESUMO
Este artigo descreve as estruturas e funções da membrana eritrocitária e sua importância na medicina transfusional. A membrana eritrocitária é uma das membranas mais conhecidas em termos de estrutura, função e genética. Como qualquer membrana plasmática, tem como função mediar transportes e, ainda, fornece ao eritrócito resistência e maleabilidade. De acordo com a International Society of Blood Transfusion (ISBT), são mais de 500 antígenos expressos na membrana das hemácias e, destes, cerca de 270 estão envolvidos nos casos de reação transfusional e doença hemolítica do feto e do recém-nascido. Na classificação feita pela ISBT, destaca-se a série de alta freqüência representada por antígenos presentes em mais de 99 por cento dos indivíduos de uma população. Estes antígenos são conhecidos também como antígenos públicos e a maioria, quando ausente, determina problemas graves do ponto de vista transfusional. Como exemplo dessa problemática, uma gestante com ausência do antígeno P já sofreu seis abortos de repetição por insuficiência placentária devido ao anticorpo formado pela ausência do antígeno. Proteínas importantes são descritas nesta revisão como: banda 3, glicoforinas, espectrina e outras. A banda 3 é a mais abundante proteína integral da membrana do eritrócito e sua principal função é mediar a troca de cloro e ânions de bicarbonato através da membrana plasmática. A segunda proteína integral mais abundante é a sialoglicoproteína glicoforina A (GPA). Com um alto conteúdo de ácido siálico, a GPA contribui com a rede de carga negativa na superfície da membrana do eritrócito, minimizando, assim, a interação célula-célula e prevenindo sua agregação. Glicoforina C (GPC) é o receptor para PfEBP-2 (baebl, EBA-140), o mais novo local de ligação identificado para o Plasmodium falciparum.O complexo terciário - espectrina, actina e 4.1R - define a rede de citoesqueleto da membrana do eritrócito e é ainda responsável pela estabilidade sob mecanismos...
This article describes the structures and functions of the erythrocyte membrane and its importance in transfusional medicine. The erythrocyte membrane is one of the best known membranes in terms of structure, function and genetic disorders. As any other plasma membrane, it mediates transport functions. It also provides the erythrocytes with their resilience and deformability. According to the International Society of Blood Transfusion (ISBT), more than 500 antigens are expressed in the erythrocyte membrane, and around 270 are involved in transfusion reaction cases and hemolytic diseases of the fetus and newborn. In the ISBT classification, the high frequency series is represented by antigens in more than 99 percent of population (high prevalence antigen). In transfusion, the absence of these antigens determines severe problems as for example, one woman without the P antigen suffered 6 repetitive miscarriages due to placental insufficiency, which was caused by an antibody formed against the absent P antigen. Some important erythrocyte membrane proteins are described here including Band 3, Glycophorins and spectrin. The most abundant integral membrane protein is Band 3 and its main function is to mediate exchange of chloride and bicarbonate anions across the plasma membrane. The second most abundant integral membrane protein in the human erythrocyte is sialoglycoprotein glycophorin A (GPA). With its high sialic acid content, GPA is the main contributor to the net negative cell-surface charge and is thus critical for minimizing cell-cell interactions and preventing red cell aggregation. Glycophorin C (GPC) is the receptor for PfEBP-2 (baebl, EBA-140), the newly identified erythrocyte binding ligand of Plasmodium falciparum. The ternary complex of spectrin, actin and 4.1R defines the nodes of the erythrocyte membrane skeletal network, and is inseparable from membrane stability when under mechanical stress. This erythrocyte membrane review...
Assuntos
Membrana Eritrocítica , Transfusão de Sangue , Glicoforinas , Proteínas , Membrana Celular , Reação Transfusional , Proteínas de Membrana , AntígenosRESUMO
Se purifica la proteína banda 3 a partir de membranas de eritrocitos humanos con rapidez y eficiencia, mediante una combinación de cromatografía de intercambio iónico en DEAE-celulosa y de afinidad mediante el empleo de una columna pCMB-Sepharose. La obtención de banda 3 permitirá investigar su posible participación en los fenómenos oclusivos en la drepanocitosis.
The band 3 protein is purified starting form the membranes of human erythrocytes with celerity and efficiency by a combination of DEAE-cellulose ion-exchange and affinity chromatography by using a pCMB-Sepharose column. The obtention of band 3 will allow to investigate its possible participation in the occlusive phenomena in drepanocytosis.