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  • 1
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    Changes in activities and isozyme patterns of glycolytic enzymes during erythroid differentiation in vitro (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-09-01
    Description: Late committed progenitor cells of erythropoiesis, CFU-E (colony- forming unit--erythroid), were isolated from mouse spleens to near homogeneity by a three-step enrichment procedure. The procedure included a four-day pretreatment of bled mice with the antibiotic thiamphenicol, a recovery period of 3 1/2 days, followed by centrifugal elutriation and Percoll density gradient centrifugation of the spleen cells. This practically pure CFU-E population was used to study some aspects of erythroid differentiation in vitro. Colony growth, as well as morphology and glycolytic enzyme activities of cells isolated at selected times of the 48-hour culture period, were determined. Marked declining activities of several enzymes, including hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase, and glucose-6- phosphate dehydrogenase, were observed during in vitro differentiation. The activity of diphosphoglycerate mutase was almost absent in the CFU- E, but progressively increased during differentiation. The isozyme distribution of aldolase and enolase did not change during CFU-E in vitro differentiation into the reticulocyte. Hexokinase (HK) in the CFU- E contained mainly a double-banded type I isozyme, in addition to a minor amount of HK II. During differentiation, a shift was noticed within the double-banded HK I region, whereas HK ii disappeared after one cell division. Pyruvate kinase in the CFU-E was characterized by the presence of both the K-type and the L-type isozyme and hybrids of these isozyme types. During in vitro differentiation, the production of the K-type isozyme rapidly stops in favor of the L type.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 2
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    Generalized hexokinase deficiency in the blood cells of a patient with nonspherocytic hemolytic anemia (1983)
    American Society of Hematology
    Details
    Publication Date: 1983-01-01
    Description: In a patient with nonspherocytic hemolytic anemia, a hexokinase deficiency was detected in the red cells (residual activity about 25% of normal) and in blood platelets (20%-35% of normal activity). Although the total hexokinase activity in lymphocytes was normal, the amount of hexokinase type I was decreased to about 50% of normal. However, the deficiency was compensated for by the appearance of type III hexokinase. Compartmentation studies with controlled digitonin- induced cell lysis showed that this type III enzyme was localized in the cytosol, while almost all hexokinase activity in normal lymphocytes is particulate. No abnormal lymphocyte functions could be detected. The patient was homozygous for the defect. The parents and three of five sibs of the patient were apparently heterozygous with residual activities of 50%-67% of normal in their red cells, but did not show any clinical signs of hexokinase deficiency. The variant enzyme had a slightly decreased affinity for MgATP2- and a strongly increased inhibition constant for glucose-1,6-P2. Affinity for glucose, heat stability, and pH optimum were normal. In the electrophoretic pattern of red cell hexokinase, only one subtype of hexokinase I could be detected, while in normal red cells, at least three subtypes are present. In the heterozygous individuals, no enzymatic abnormalities could be detected, except for an aberration in the electropherogram of one sib.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 3
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    Platelet functions and energy metabolism in a patient with hexokinase deficiency (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-01-01
    Description: We have studied the regeneration of adenosine triphosphate (ATP) in the glycolytic pathway in platelets with a 75% reduction in hexokinase (HK) activity and have investigated aggregation and Ca2+ secretion. HK- deficient platelets had a normal glycolytic flux in the resting state, but responded insufficiently to stimulation with thrombin (5 U/ml). In contrast, glycogen contents and glycogenolysis were normal. When the metabolic adenine nucleotides were labeled with 14C-adenine, the patient's platelets showed a normal adenylate energy charge and a normal level of 14C-ATP. However, the inhibitor of mitochondrial energy generation, CN-, induced a weaker fall in 14C-ATP in the patient's platelets than in the controls. Analysis of secretion markers revealed decreased amounts of granule-bound ATP and secretable Ca2+, whereas granule-bound adenosine diphosphate (ADP), beta-thromboglobulin, N- acetyl-beta-D-glucosaminidase, and beta-glucuronidase were within the normal range. Aggregation and Ca2+ secretion induced by 5 U/ml thrombin were normal and were not changed in the presence of inhibitors of mitochondrial and glycogenolytic energy generation. Aggregation was also normal at 0.1 U/ml thrombin and was independent of these inhibitors, but Ca2+ secretion was greatly impaired when mitochondrial and glycogenolytic ATP resynthesis was abolished. These findings indicate that a severe reduction in HK activity causes insufficient acceleration of the glycolytic flux during stimulation with thrombin. This leads to impaired dense granule secretion in conditions where secretion depends on concurrent ATP resynthesis and glycolysis is rate limiting.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 4
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    Unknown
    Generalized hexokinase deficiency in the blood cells of a patient with nonspherocytic hemolytic anemia (1983)
    American Society of Hematology
    Details
    Publication Date: 1983-01-01
    Description: In a patient with nonspherocytic hemolytic anemia, a hexokinase deficiency was detected in the red cells (residual activity about 25% of normal) and in blood platelets (20%-35% of normal activity). Although the total hexokinase activity in lymphocytes was normal, the amount of hexokinase type I was decreased to about 50% of normal. However, the deficiency was compensated for by the appearance of type III hexokinase. Compartmentation studies with controlled digitonin- induced cell lysis showed that this type III enzyme was localized in the cytosol, while almost all hexokinase activity in normal lymphocytes is particulate. No abnormal lymphocyte functions could be detected. The patient was homozygous for the defect. The parents and three of five sibs of the patient were apparently heterozygous with residual activities of 50%-67% of normal in their red cells, but did not show any clinical signs of hexokinase deficiency. The variant enzyme had a slightly decreased affinity for MgATP2- and a strongly increased inhibition constant for glucose-1,6-P2. Affinity for glucose, heat stability, and pH optimum were normal. In the electrophoretic pattern of red cell hexokinase, only one subtype of hexokinase I could be detected, while in normal red cells, at least three subtypes are present. In the heterozygous individuals, no enzymatic abnormalities could be detected, except for an aberration in the electropherogram of one sib.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 5
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    Distribution of phosphorylated metabolites and magnesium in the red cells of a patient with hyperactive pyruvate kinase (1988)
    American Society of Hematology
    Details
    Publication Date: 1988-10-01
    Description: The intracellular distribution of adenosine 5′-triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) was studied in the red cells of a patient with a “high-ATP syndrome' by using 31P nuclear magnetic resonance. In this patient, red cell ATP was increased 2.5-fold, whereas 2,3-DPG was decreased fourfold due to the presence of a hyperactive pyruvate kinase. In oxygenated red cells, these abnormal concentrations were reflected to the same extent in all complexes in which ATP and 2,3-DPG take part. The diminished amount of 2,3-DPG bound to hemoglobin was almost completely replaced by ATP-hemoglobin complexes. Therefore, free hemoglobin was only slightly increased. In deoxygenated cells, the relative distribution of ATP and 2,3-DPG complexes was significantly disturbed. The main difference was a shift in the ratio of magnesium ATP (MgATP) over the ATP-hemoglobin complex; 74% of total ATP was complexed to hemoglobin (45% in normal cells), whereas the concentration of MgATP was only slightly increased with respect to normal. The shortage in 2,3-DPG bound to hemoglobin could partially be replenished by an increase in hemoglobin (Mg) ATP complexes. Therefore, the amount of uncomplexed hemoglobin raised from 15% in normal cells to 38% in the patient's cells. As a result, the oxygen-dissociation curve was only moderately shifted to the left. It is concluded that the regulatory role of 2,3-DPG in oxygen transport is taken over in part by (Mg) ATP in this patient. In both aerobic and anaerobic cells, the increase in magnesium bound to ATP, either free or bound to hemoglobin, exceeds the decrease in 2,3-DPG Mg complex. In spite of this, the amount of intracellular free Mg++ was normal or slightly lowered. This suggests the presence of a compensatory mechanism by which the amount of total cellular magnesium could be increased.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 6
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    Unknown
    Platelet functions and energy metabolism in a patient with hexokinase deficiency (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-01-01
    Description: We have studied the regeneration of adenosine triphosphate (ATP) in the glycolytic pathway in platelets with a 75% reduction in hexokinase (HK) activity and have investigated aggregation and Ca2+ secretion. HK- deficient platelets had a normal glycolytic flux in the resting state, but responded insufficiently to stimulation with thrombin (5 U/ml). In contrast, glycogen contents and glycogenolysis were normal. When the metabolic adenine nucleotides were labeled with 14C-adenine, the patient's platelets showed a normal adenylate energy charge and a normal level of 14C-ATP. However, the inhibitor of mitochondrial energy generation, CN-, induced a weaker fall in 14C-ATP in the patient's platelets than in the controls. Analysis of secretion markers revealed decreased amounts of granule-bound ATP and secretable Ca2+, whereas granule-bound adenosine diphosphate (ADP), beta-thromboglobulin, N- acetyl-beta-D-glucosaminidase, and beta-glucuronidase were within the normal range. Aggregation and Ca2+ secretion induced by 5 U/ml thrombin were normal and were not changed in the presence of inhibitors of mitochondrial and glycogenolytic energy generation. Aggregation was also normal at 0.1 U/ml thrombin and was independent of these inhibitors, but Ca2+ secretion was greatly impaired when mitochondrial and glycogenolytic ATP resynthesis was abolished. These findings indicate that a severe reduction in HK activity causes insufficient acceleration of the glycolytic flux during stimulation with thrombin. This leads to impaired dense granule secretion in conditions where secretion depends on concurrent ATP resynthesis and glycolysis is rate limiting.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 7
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    Unknown
    Distribution of phosphorylated metabolites and magnesium in the red cells of a patient with hyperactive pyruvate kinase (1988)
    American Society of Hematology
    Details
    Publication Date: 1988-10-01
    Description: The intracellular distribution of adenosine 5′-triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) was studied in the red cells of a patient with a “high-ATP syndrome' by using 31P nuclear magnetic resonance. In this patient, red cell ATP was increased 2.5-fold, whereas 2,3-DPG was decreased fourfold due to the presence of a hyperactive pyruvate kinase. In oxygenated red cells, these abnormal concentrations were reflected to the same extent in all complexes in which ATP and 2,3-DPG take part. The diminished amount of 2,3-DPG bound to hemoglobin was almost completely replaced by ATP-hemoglobin complexes. Therefore, free hemoglobin was only slightly increased. In deoxygenated cells, the relative distribution of ATP and 2,3-DPG complexes was significantly disturbed. The main difference was a shift in the ratio of magnesium ATP (MgATP) over the ATP-hemoglobin complex; 74% of total ATP was complexed to hemoglobin (45% in normal cells), whereas the concentration of MgATP was only slightly increased with respect to normal. The shortage in 2,3-DPG bound to hemoglobin could partially be replenished by an increase in hemoglobin (Mg) ATP complexes. Therefore, the amount of uncomplexed hemoglobin raised from 15% in normal cells to 38% in the patient's cells. As a result, the oxygen-dissociation curve was only moderately shifted to the left. It is concluded that the regulatory role of 2,3-DPG in oxygen transport is taken over in part by (Mg) ATP in this patient. In both aerobic and anaerobic cells, the increase in magnesium bound to ATP, either free or bound to hemoglobin, exceeds the decrease in 2,3-DPG Mg complex. In spite of this, the amount of intracellular free Mg++ was normal or slightly lowered. This suggests the presence of a compensatory mechanism by which the amount of total cellular magnesium could be increased.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
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  • 8
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    Unknown
    Changes in activities and isozyme patterns of glycolytic enzymes during erythroid differentiation in vitro (1984)
    American Society of Hematology
    Details
    Publication Date: 1984-09-01
    Description: Late committed progenitor cells of erythropoiesis, CFU-E (colony- forming unit--erythroid), were isolated from mouse spleens to near homogeneity by a three-step enrichment procedure. The procedure included a four-day pretreatment of bled mice with the antibiotic thiamphenicol, a recovery period of 3 1/2 days, followed by centrifugal elutriation and Percoll density gradient centrifugation of the spleen cells. This practically pure CFU-E population was used to study some aspects of erythroid differentiation in vitro. Colony growth, as well as morphology and glycolytic enzyme activities of cells isolated at selected times of the 48-hour culture period, were determined. Marked declining activities of several enzymes, including hexokinase, phosphofructokinase, aldolase, enolase, pyruvate kinase, and glucose-6- phosphate dehydrogenase, were observed during in vitro differentiation. The activity of diphosphoglycerate mutase was almost absent in the CFU- E, but progressively increased during differentiation. The isozyme distribution of aldolase and enolase did not change during CFU-E in vitro differentiation into the reticulocyte. Hexokinase (HK) in the CFU- E contained mainly a double-banded type I isozyme, in addition to a minor amount of HK II. During differentiation, a shift was noticed within the double-banded HK I region, whereas HK ii disappeared after one cell division. Pyruvate kinase in the CFU-E was characterized by the presence of both the K-type and the L-type isozyme and hybrids of these isozyme types. During in vitro differentiation, the production of the K-type isozyme rapidly stops in favor of the L type.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
    Published by American Society of Hematology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
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