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Query: UMLS:C0019045 (hemoglobinopathies)
 2,704 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of fetal hemoglobin was investigated in in vitro cultures of erythroid precursors isolated from peripheral blood of normal individuals, newborns and of subjects with different hemoglobinopathies. Synthesis of hemoglobin was assessed by 35s-methionine labeling of cultures and measurement of the radioactivity incorporated into the hemoglobins A2, A, F and S isolated by column chromatography on DE 52 cellulose. The erythroid precursors from most of the studied individuals cultured in in vitro system responded with synthesized an average of 15% of Hb F while cultures from newborns produced an average of 60% of Hb F in comparison of 73% of Hb F in peripheral blood of the same newborns. Erythroid precusors from subjects heterozygotes for beta-thalassemia, heterozygotes for HPFH, and homozygotes for Hb S produced an average of 20%, 43% and 30% of Hb F, respectively, in comparison of 7%, 14% and 9% of Hb F, respectively, present in the RBC of the same individuals. These data support the previously published results (6-11) that erythroid bursts in culture reactivate the structural genes for the gamma chain synthesis.
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PMID:[Preferential synthesis of fetal hemoglobin in in vitro cultures of erythroid precursors from peripheral blood of healthy persons and those with hemoglobinopathies]. 9 30

In this article we have surveyed the current state of knowledge regarding the accumulation of globin mRNA and hemoglobin in red cells. We have attempted to examine the interplay of numerous processes that seem to be necessary to achieve this highly differentiated state. Finally, we have made an effort to formulate some of the mechanisms whereby individual red cells may come to contain varying proportions of specific hemoglobins. The past several years have been characterized by a veritable explosion of knowledge concerning the globin structure genes, and the structure, transcription, processing and function of globin mRNA in erythroid cells. It now seems possible to analyze the earlier stages of erythropoiesis by cultivation and examination of erythroid colonies in vitro. The primary differentiation events leading to the production of specific globins, especially for hemoglobin F production in man, are now experimentally accessible. There is good reason to hope that these advances will soon permit achievement of the long desired therapeutic goal of enhancing hemoglobin F synthesis in patients with severe beta-chain hemoglobinopathies. Our aim has been to review the scientific information that might provide the rationable for amelioration of the clinical phenotypes in patients inheriting abnormal globin genes.
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PMID:Regulation of hemoglobin synthesis during the development of the red cell (third of three parts). 33 41

Serial microscopic immunodiffusion assays of F cells, i.e., erythrocytes that contain fetal hemoglobin (HbF), in four individuals recovering from anemia demonstrate initial increases in the percentage of circulating reticulocytes that contain HbF (F reticulocytes) and subsequent increases in the percentage of mature erythrocytes that contain HbF (F erythrocytes). In one individual responding to therapy for iron-deficiency anemia, the average percentage of F reticulocytes increased from 4.8+/-1.1 to 16.0+/-2.8% (mean+/-SD), while the mean level of F erythrocytes increased from 3.5+/-0.7 to 7.2+/-0.6%. Two normal children with transient erythroblastopenia exhibited F reticulocyte percentages of 71.3+/-6.7 and 41.5+/-1.5%, respectively, when erythropoiesis resumed. With recovery these values fell to finally measured values of 33.7+/-4.7 and 12.6+/-1.1%, respectively. In an adolescent with sickle cell anemia, F-reticulocyte percentages fluctuated between 0.6+/-1.1 and 34.0+/-2.8% and paralleled the rise and fall of total reticulocytes associated with therapy for a nasopharyngeal carcinoma. Such findings suggest that first, the production of F cells and non-F cells are separately regulated. Second, F-cell production is preferentially stimulated during escape from erythropoietic suppression and selectively depressed at the start of suppression. Third, during escape from erythropoietic suppression, F-cell production in vivo resembles that reported for in vitro cultures of erythroid stem cells. Fourth, individuals with sickle cell anemia, like individuals without hemoglobinopathies, can change their relative level of F-cell production.
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PMID:Production of erythrocytes that contain fetal hemoglobin in anemia. Transient in vivo changes. 42 49

The biosynthesis of two types of human fetal hemoglobin (Hb F), namely Hb F with G gamma chains having glycine in position 136 and Hb F with A gamma chains having alanine in position 136, was studied in blood samples and in cultures of erythroid precursors from blood of patients with different hemoglobinopathies. High pressure liquid chromatography (HPLC) was adapted to allow the separation of the methionyl-containing tryptic peptides G gamma T-15 and A gamma T-15 (which include the Gly leads to Ala polymorphism at position 136) from a digest of microquantitites of 35S-methionyl labelled Hb F. This method was sensitive enough to quantitate the relative production of the G ygamma and A gamma chains by erythroid colonies derived from cloned Burst Forming Units (bfu-e) which were cultured for 16 days on methylcellulose. The production of Hb F in these colonies was generally higher than the level of Hb F in blood except for subjects with the G gamma A gamma-HPFH heterozygosity. The G gamma to A gamma ratio in the Nb F produced in cultures of cells from G gamma delta beta-thalassemia or G gamma-HPFH heterozygotes was lower and that from A gamma-HPFH heterosygotes was higher than the ratios in the Hb F of the corresponding peripheral blood cells. Mixtures of G gamma and A gamma chains were present in cell cultures of SS patients, beta+-thalassemia homozygotes and G gamma A gamma-HPFH heterozygotes in a ratio similar to that in the Hb F of mature red cells. These data suggest that erythroblasts in BFU-E derived colonies reactivate all available gamma chain structural genes, both in cis and in trans to the abnormal determinant. Hb F biosynthesis by adult blood samples concerns primarily the G gamma chains. This was particularly striking for blood samples in which erythroblasts were absent and the biosynthesis took place in fetal reticulocytes. Thus, the F-retuculocytes in blood of A gamma-HPFH heterozygotes with about 5% Hb F of the A gamma type produced primarily Hb F with G gamma chains. Similar differences were observed for G gamma A gamma-HPFH heterozygotes and, less strinkingly, for SS patients. A satisfactory explanation for this observation has not yet been obtained.
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PMID:The synthesis of fetal hemoglobin types in red blood cells and in BFU-E derived colonies from peripheral blood of patients with sickle cell anemia, beta+ - and delta beta-thalassemia, various forms of hereditary persistence of fetal hemoglobin, normal adults and newborn. 50 Mar 69

Hb M Akita disease is a cyanotic hemoglobinopathy found in Akita Prefecture, Japan. The abnormal hemoglobin was found to be the same as Hb M Hyde Park (beta92 His replaced by Tyr) by chemical analysis in 1967. In this disease signs of accelerated hemolysis (serum bilirubin, 2.4 mg/dl; splenomegaly, 2 finger breadths; Hb, 10.7 g/dl; reticulocyte index, 2.7) were noted, but the causes of its slight anemia were revealed to be fairly complex by ferrokinetic study, RBC life-span measurement, and 99mTc myeloscintigram. The anemia in this disease is caused not only by shortened erythrocyte survival (T 1/2 = 11.5 days by 51Cr-tagging method) and sequestration of red cells in the spleen (Spleen: liver ratio = 2.5 approximately 3.0 by 51Cr-surface counting), but also by slow supply of erythrocytes to the peripheral blood from the bone marrow, presumably, related to the existence of unstable Hb M Akita and its derivative (Hb Akita) in the erythroid cells. Both Carrell's isopropanol test and Heinz body formation test were positive. In spite of maximally increased total erythropoiesis (8 times as high as the normal level; M:E ratio = 0.22:1.0), supply of red cells from the bone marrow to the peripheral blood was significantly decreased. The distribution of hematopoietic sites throughout the body was reasonably uniform.
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PMID:Altered erythropoiesis and increased hemolysis in hemoglobin M Akita (M Hyde Park beta92 His replaced by Tyr) disease. 105 75

Gene therapy of severe hemoglobinopathies will require high-level expression of a transferred globin gene in erythroid cells. Distant regulatory elements flanking the beta-globin gene cluster, the locus control region, are needed for appropriate expression. We have explored the use of a human parvovirus, the adeno-associated virus (AAV), for globin gene transfer. The human A gamma-globin gene, linked to hypersensitivity site 2 from the locus control region of the beta-globin gene cluster, was subcloned into a plasmid (psub201) containing the AAV inverted terminal repeats. This construct was cotransfected with a helper plasmid containing trans-acting AAV genes into human 293 cells that had been infected with adenovirus. The recombinant AAV vector containing hypersensitivity site 2 stably introduced on average one or two unrearranged proviral copies into human K562 erythroleukemia cells. The transferred globin gene exhibited normal regulation upon hemin induction of erythroid maturation and was expressed at a level equivalent to a native chromosomal A gamma-globin gene.
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PMID:Regulated high level expression of a human gamma-globin gene introduced into erythroid cells by an adeno-associated virus vector. 132 31

There is considerable interest in identifying nontoxic differentiation inducers for the treatment of various malignant and nonmalignant blood disorders, including inborn beta-chain hemoglobinopathies. Using the human leukemic K562 cell line as a model, we explored the efficacy of phenylacetate, an amino acid derivative with a low toxicity index when administered to humans. Treatment of K562 cultures with pharmacologically attainable concentrations of phenylacetate resulted in erythroid differentiation, evident by the reduced growth rate and increased hemoglobin production. The effect was time- and dose-dependent, further augmented by glutamine starvation (phenylacetate is known to deplete circulating glutamine in vivo), and reversible upon cessation of treatment. Molecular analysis showed that phenylacetate induced gamma globin gene expression with subsequent accumulation of the fetal form of hemoglobin (HbF). Interestingly, the addition of phenylacetate to antitumor agents of clinical interest, eg, hydroxyurea and 5-azacytidine, caused superinduction of HbF biosynthesis. The results suggest that phenylacetate, used alone or in combination with other drugs, might offer a safe and effective new approach to treatment of some hematopoietic neoplasms and severe hemoglobinopathies.
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PMID:Induction of erythroid differentiation and fetal hemoglobin production in human leukemic cells treated with phenylacetate. 138 30

Blood erythroid progenitors (BFU-E) from patients with sickle and thalassemic syndromes were compared with those from normal individuals. The day of maximal colony formation in methyl cellulose was slightly later in the cultures from the patients with hemoglobinopathies than in the normal cultures. The number of colonies/100,000 mononuclear cells was similar in all cultures on day 13, but was higher in the hemoglobinopathy cultures on the day of maximal growth. The number of BFU-E/mL of blood was significantly higher than normal at all times in both sickle cell anemia and thalassemia. The proportional synthesis of gamma globin was twice normal in all sickle cultures, and 4 times normal in those from beta+-thalassemia. Hemin and interleukin-3 increased the numbers of erythroid colonies in all cultures, but did not consistently alter the globin synthesis patterns. Each progenitor population has a unique pattern in terms of time course, number of BFU-E, and level of gamma globin synthesis. These features indicate distinct types of BFU-E, or differences in accessory cells, or both, which distinguish blood-borne erythropoiesis in normals and those with hemoglobinopathies.
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PMID:Sickle and thalassemic erythroid progenitor cells are different from normal. 148 17

Human erythroblasts are a logical target for studies of expression of transferred globin genes because high-level expression is a prerequisite for gene therapy of hemoglobinopathies. Early erythroid progenitors (erythroid burst-forming units, BFU-E) are readily available from human peripheral blood and can be cultured to produce erythroblasts. However, conditions for efficient transfer into these normal progenitors have not been previously described. Here we demonstrate efficient transfer of the neomycin resistance gene into human peripheral blood BFU-E using the retrovirus vector, N2. We show that liquid culture of mononuclear cells from peripheral blood for 18-24 h prior to retroviral infection leads to increased transfer efficiency of N2 as determined by G418 resistance, and we are able to detect viral DNA by polymerase chain reaction (PCR) analysis. In addition, a second retrovirus, beta(gamma)-SVX, prepared with a human beta-globin gene containing a gamma-globin second exon to facilitate transcript detection and the 3'-enhancer sequence, was also used to determine whether similar results could be obtained when more than one gene is transferred. Using the beta(gamma)-SVX virus, increased transfer efficiency into BFU-E was similarly found after liquid culture for up to 4 days. Expression of the transferred globin gene was also detected by PCR analysis of cDNA made from erythroblast RNA. The human peripheral blood BFU-E system described should allow determination of sequences required for high-level expression of transferred globin and other erythroid genes.
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PMID:Retroviral transfer of genes into erythroid progenitors derived from human peripheral blood. 169 73

Interferon-gamma (IFN-gamma) has been shown to influence globin gene expression in cord blood and normal adult progenitor-derived erythroblasts. To explore the influence of IFN-gamma on fetal hemoglobin (HbF) synthesis in the hemoglobinopathies, erythroid progenitors (BFU-E, burst forming unit-erythroid) from patients with sickle cell anemia (SCA) and thalassemia were co-cultured with or without IFN-gamma. Hemoglobin content in progenitor-derived erythroblasts was assessed by radioligand assay (RIA). Co-culture of erythroid progenitors from 12 SCA patients with 200-400 U/ml of IFN-gamma resulted in a significant decrease in picograms of HbF and percent HbF per BFU-E-derived erythroblast. The mean decrease (+/- SEM) of picograms of HbF per cell and percent of HbF was by 42 +/- 9% and 35 +/- 8% of control cultures, respectively. Co-culture of erythroid progenitors from 10 patients with thalassemia major or thalassemia variant (HPFH/thalassemia, sickle/beta 0-thalassemia) with 200 U/ml IFN-gamma also resulted in a significant decrease in picograms and percent of HbF per BFU-E-derived erythroblast. IFN-gamma treatment also inhibited the enhancement in gamma-globin synthesis induced in culture by butyric acid. Erythroid progenitors from 2 patients with SCA, 1 patient with sickle/beta 0-thalassemia, and 1 patient with HbE/beta 0-thalassemia were co-cultured with IFN-gamma, L-alpha-amino-n-butyric acid, or both. HbF content (expressed as picograms HbF/cell) was decreased in samples co-cultured with IFN, increased in cultures with L-alpha-amino-n-butyric acid, but remained at control values in cultures treated with IFN plus L-alpha-amino-n-butyric acid. These data demonstrate that IFN-gamma is an environmental factor that influences gamma-globin gene expression in the beta hemoglobinopathies in vitro.
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PMID:Interferon-gamma modulates fetal hemoglobin synthesis in sickle cell anemia and thalassemia. 170 29


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