By weight, phospholipids make up approximately 25% of the plasma membrane of mature human erythrocytes. The four major phospholipid species present in the membrane (PC, PE, PS, and SM) are distributed asymmetrically across the bilayer leaflet resulting in an enrichment of choline-phospholipid (PC and SM) in the outer leaflet and of amino-phospholipid (PE and PS) in the cytoplasmic leaflet. This asymmetric organization is preferentially maintained through complex, and at present, poorly understood noncovalent interactions between specific membrane lipids and proteins (in particular, a stabilizing role for the skeletal protein spectrin and band 4.1 have been implicated), although other considerations such as phospholipid net charge, size, and degree of acyl chain unsaturation may also be involved. In certain red cell pathologies, or following experimental manipulation, there is a partial loss of this asymmetry (summarized in Tables XVI, XVII) often resulting in increases in the outer leaflet content of amino-phospholipids and subsequent expression of altered membrane surface properties. Some of these abnormal properties may have pathophysiologic consequence; indeed, red cell membranes displaying increased levels of surface amino-phospholipids have been shown to be potent procoagulants and demonstrate enhanced intermembrane interactions with both model (liposomes) and biologic (mononuclear phagocytes) membranes. Redistribution of membrane phospholipids may not occur homogeneously throughout an entire leaflet but may be restricted to specific membrane regions. These studies strongly suggest that the maintenance of phospholipid asymmetry in human red cell membranes is not a trivial event but probably represents a homeostatic mechanism, the failure of which may lead to alterations in normal erythrocyte functions, and ultimately, survival.
{"title":"Plasma membrane phospholipid organization in human erythrocytes.","authors":"R S Schwartz, D T Chiu, B Lubin","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>By weight, phospholipids make up approximately 25% of the plasma membrane of mature human erythrocytes. The four major phospholipid species present in the membrane (PC, PE, PS, and SM) are distributed asymmetrically across the bilayer leaflet resulting in an enrichment of choline-phospholipid (PC and SM) in the outer leaflet and of amino-phospholipid (PE and PS) in the cytoplasmic leaflet. This asymmetric organization is preferentially maintained through complex, and at present, poorly understood noncovalent interactions between specific membrane lipids and proteins (in particular, a stabilizing role for the skeletal protein spectrin and band 4.1 have been implicated), although other considerations such as phospholipid net charge, size, and degree of acyl chain unsaturation may also be involved. In certain red cell pathologies, or following experimental manipulation, there is a partial loss of this asymmetry (summarized in Tables XVI, XVII) often resulting in increases in the outer leaflet content of amino-phospholipids and subsequent expression of altered membrane surface properties. Some of these abnormal properties may have pathophysiologic consequence; indeed, red cell membranes displaying increased levels of surface amino-phospholipids have been shown to be potent procoagulants and demonstrate enhanced intermembrane interactions with both model (liposomes) and biologic (mononuclear phagocytes) membranes. Redistribution of membrane phospholipids may not occur homogeneously throughout an entire leaflet but may be restricted to specific membrane regions. These studies strongly suggest that the maintenance of phospholipid asymmetry in human red cell membranes is not a trivial event but probably represents a homeostatic mechanism, the failure of which may lead to alterations in normal erythrocyte functions, and ultimately, survival.</p>","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"5 ","pages":"63-112"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14999376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Regulation of blood coagulation factor levels in plasma.","authors":"M Karpatkin, S Karpatkin","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"5 ","pages":"113-25"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14998066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In summary, the beta-thalassemias are models for the study of human genetic disease. Defining the genetic defects in and surrounding the beta-globin gene in the beta(+)- and the beta(0)-thalassemias has resulted in new insights into the relationships between changes in gene structure and abnormalities in gene function. The region 5' to the beta-gene, the coding regions within the gene, and the IVS have all been found to contain single nucleotide defects which diminish or abolish beta-globin mRNA production and the production of beta-globin. The ability to isolate beta-globin genes by cloning, and to express these beta-globin genes in cells, has given remarkable insights into the relationship between globin gene structure and globin gene function. In addition, new technology is available for the antenatal diagnosis of the beta-thalassemias based on the knowledge of the specific defects in these genes, with the use of oligomers to detect single nucleotide changes. Finally, recent advances have suggested new approaches to gene therapy in these disorders using gene transfer.
{"title":"Genetic defects in the thalassemias.","authors":"A Bank","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In summary, the beta-thalassemias are models for the study of human genetic disease. Defining the genetic defects in and surrounding the beta-globin gene in the beta(+)- and the beta(0)-thalassemias has resulted in new insights into the relationships between changes in gene structure and abnormalities in gene function. The region 5' to the beta-gene, the coding regions within the gene, and the IVS have all been found to contain single nucleotide defects which diminish or abolish beta-globin mRNA production and the production of beta-globin. The ability to isolate beta-globin genes by cloning, and to express these beta-globin genes in cells, has given remarkable insights into the relationship between globin gene structure and globin gene function. In addition, new technology is available for the antenatal diagnosis of the beta-thalassemias based on the knowledge of the specific defects in these genes, with the use of oligomers to detect single nucleotide changes. Finally, recent advances have suggested new approaches to gene therapy in these disorders using gene transfer.</p>","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"5 ","pages":"1-23"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14998065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ferritin: an interim review.","authors":"A Jacobs","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"5 ","pages":"25-62"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14998067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Genetic deficiencies of adenosine deaminase and purine nucleoside phosphorylase and their implications for therapy of leukemias.","authors":"R Hirschhorn, H Ratech","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"4 ","pages":"1-35"},"PeriodicalIF":0.0,"publicationDate":"1983-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17471372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Physiologic mechanisms and the hematopoietic effects of the androstanes and their derivatives.","authors":"F H Gardner, E C Besa","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"4 ","pages":"123-95"},"PeriodicalIF":0.0,"publicationDate":"1983-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17412118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Alpha-thalassemia.","authors":"D R Higgs, D J Weatherall","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"4 ","pages":"37-97"},"PeriodicalIF":0.0,"publicationDate":"1983-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17412119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Genetics of complement.","authors":"D Raum, V H Donaldson, F S Rosen, C A Alper","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":75765,"journal":{"name":"Current topics in hematology","volume":"3 ","pages":"111-74"},"PeriodicalIF":0.0,"publicationDate":"1980-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"18082643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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