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  • 1
    Publication Date: 1991-05-01
    Description: A new case of heterozygous dysfibrinogenemia characterized by the replacement of NH2-terminal amino acid of fibrin beta-chain was found in a 50-year-old man. Despite a prolonged thrombin time, the propositus' fibrinogen had a normal reptilase time with the normal release of fibrinopeptide A. Release of fibrinopeptide B by thrombin was strongly affected, but a very high concentration of thrombin almost completely released fibrinopeptide B with a normal elution pattern on reversed-phase high performance liquid chromatography (HPLC). Lysylendopeptidase-cleavage of purified B beta-chains analyzed on HPLC showed the decrease of one peptide compared with the normal and the appearance of an abnormal peptide peak. These peptides were treated with thrombin and further separated on HPLC. Amino acid sequence analysis of the abnormal peptide demonstrated that B beta glycine-15, NH2-terminus of the fibrin beta-chain, was replaced by cysteine. These findings will be of particular importance because they strongly support the hypothesis that the NH2-terminal portion of the fibrin beta-chain is involved in the polymerization reaction by thrombin. The propositus' daughter and two sisters had the same abnormal fibrinogen. This unique inherited abnormal fibrinogen was designated as fibrinogen Ise. During these studies, we found that a very high concentration of thrombin cleaves not only the A alpha Arg19-Val20 bond but also the COOH- terminal region of alpha-chains, which results in the generation of further degraded alpha-chains with apparent molecular weights of 44,000 or less.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 2
    Publication Date: 1991-05-01
    Description: A new case of heterozygous dysfibrinogenemia characterized by the replacement of NH2-terminal amino acid of fibrin beta-chain was found in a 50-year-old man. Despite a prolonged thrombin time, the propositus' fibrinogen had a normal reptilase time with the normal release of fibrinopeptide A. Release of fibrinopeptide B by thrombin was strongly affected, but a very high concentration of thrombin almost completely released fibrinopeptide B with a normal elution pattern on reversed-phase high performance liquid chromatography (HPLC). Lysylendopeptidase-cleavage of purified B beta-chains analyzed on HPLC showed the decrease of one peptide compared with the normal and the appearance of an abnormal peptide peak. These peptides were treated with thrombin and further separated on HPLC. Amino acid sequence analysis of the abnormal peptide demonstrated that B beta glycine-15, NH2-terminus of the fibrin beta-chain, was replaced by cysteine. These findings will be of particular importance because they strongly support the hypothesis that the NH2-terminal portion of the fibrin beta-chain is involved in the polymerization reaction by thrombin. The propositus' daughter and two sisters had the same abnormal fibrinogen. This unique inherited abnormal fibrinogen was designated as fibrinogen Ise. During these studies, we found that a very high concentration of thrombin cleaves not only the A alpha Arg19-Val20 bond but also the COOH- terminal region of alpha-chains, which results in the generation of further degraded alpha-chains with apparent molecular weights of 44,000 or less.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 3
    Publication Date: 1990-01-15
    Description: In order to examine the sequential expression of major blood group antigens on human erythroblasts, a selective two phase liquid culture system for erythroid progenitors was established. After mononuclear cells obtained from peripheral blood were cultured in the presence of phytohemagglutinin stimulated-leukocyte conditioned medium (PHA-LCM) for 7 days (the first phase), nonphagocytic cells were recultured under hypoxic culture conditions containing 30% fetal calf serum, 1% bovine serum albumin, 300 micrograms/mL transferrin and 2 U/mL recombinant erythropoietin (the second phase). Mature (orthochromatic) erythroblasts were observed on day 4 of the second phase, and reached 57.1 +/- 3.1% of total cells on day 8, followed by the appearance of denucleated red cells, equivalent to mature red cells in peripheral blood. Hemoglobin contents reached the level of 16.8 +/- 0.7 micrograms/10(6) cells on day 8. Flow cytometric analyses revealed that, on day 3 of the second phase, cells became blood type M-positive, corresponding to the maturation of erythroid cells. Regarding the expression of ABH blood group antigens, a small number of blood type H- positive cells were initially detected on day 0 of the second phase, while blood type A-positive cells, which essentially were not observed on day 0, increased gradually corresponding to the extent of erythroid maturation. In the present system, Lewis and P1 blood group antigens were expressed at day 5 of the second phase, although autologous plasma was required to determine the expression of Lewis blood group antigens. This culture system is beneficial for studies on normal and abnormal human red cell membranes, because the erythroid progenitors in human peripheral blood were used, and a reasonable number of erythroid cells (0.5 to 1.5 x 10(7] was obtained with good maturation.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
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  • 4
    Publication Date: 1992-10-15
    Description: A novel spectrin variant carrying a truncated beta-chain and designated Spectrin Tokyo (beta 220/216) is presented. It was associated with elliptocytosis and moderate uncompensated hemolysis. The dimer self- association was reduced. An increase of the alpha I 74-Kd fragment was detected upon partial trypsin digestion. Analysis of cDNA and genomic DNA showed a 1-base deletion in codon 2059 (GCC AGC--〉GCA GCT; Ala-Ser-- 〉Ala-Ala) that belongs to exon X of spectrin beta-gene. A missense sequence extended down to (new) codon 2075. Serine 2060, a potential phosphorylation site, was replaced by alanine. The shortened beta-chain failed to undergo phosphorylation in vitro. Spectrin Tokyo shared the same stop codon, overlapping normal codons 2076 and 2077 (CTG AAA), as Spectrin Nice (beta 220/216), which is caused by a dinucleotide insertion in codon 2046 and contains 2076 amino acids. However, for some reason, Spectrin Tokyo had a lower incorporation level into the membrane than Spectrin Nice.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 5
    Publication Date: 1992-10-15
    Description: A novel spectrin variant carrying a truncated beta-chain and designated Spectrin Tokyo (beta 220/216) is presented. It was associated with elliptocytosis and moderate uncompensated hemolysis. The dimer self- association was reduced. An increase of the alpha I 74-Kd fragment was detected upon partial trypsin digestion. Analysis of cDNA and genomic DNA showed a 1-base deletion in codon 2059 (GCC AGC--〉GCA GCT; Ala-Ser-- 〉Ala-Ala) that belongs to exon X of spectrin beta-gene. A missense sequence extended down to (new) codon 2075. Serine 2060, a potential phosphorylation site, was replaced by alanine. The shortened beta-chain failed to undergo phosphorylation in vitro. Spectrin Tokyo shared the same stop codon, overlapping normal codons 2076 and 2077 (CTG AAA), as Spectrin Nice (beta 220/216), which is caused by a dinucleotide insertion in codon 2046 and contains 2076 amino acids. However, for some reason, Spectrin Tokyo had a lower incorporation level into the membrane than Spectrin Nice.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 6
    Publication Date: 1990-01-15
    Description: In order to examine the sequential expression of major blood group antigens on human erythroblasts, a selective two phase liquid culture system for erythroid progenitors was established. After mononuclear cells obtained from peripheral blood were cultured in the presence of phytohemagglutinin stimulated-leukocyte conditioned medium (PHA-LCM) for 7 days (the first phase), nonphagocytic cells were recultured under hypoxic culture conditions containing 30% fetal calf serum, 1% bovine serum albumin, 300 micrograms/mL transferrin and 2 U/mL recombinant erythropoietin (the second phase). Mature (orthochromatic) erythroblasts were observed on day 4 of the second phase, and reached 57.1 +/- 3.1% of total cells on day 8, followed by the appearance of denucleated red cells, equivalent to mature red cells in peripheral blood. Hemoglobin contents reached the level of 16.8 +/- 0.7 micrograms/10(6) cells on day 8. Flow cytometric analyses revealed that, on day 3 of the second phase, cells became blood type M-positive, corresponding to the maturation of erythroid cells. Regarding the expression of ABH blood group antigens, a small number of blood type H- positive cells were initially detected on day 0 of the second phase, while blood type A-positive cells, which essentially were not observed on day 0, increased gradually corresponding to the extent of erythroid maturation. In the present system, Lewis and P1 blood group antigens were expressed at day 5 of the second phase, although autologous plasma was required to determine the expression of Lewis blood group antigens. This culture system is beneficial for studies on normal and abnormal human red cell membranes, because the erythroid progenitors in human peripheral blood were used, and a reasonable number of erythroid cells (0.5 to 1.5 x 10(7] was obtained with good maturation.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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