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Biomedical subjects

E Beutler

Publications and source records attributed to E Beutler.

At least 289 records · Page 16Linked to original sources
PubMed1985

Heterogeneity in type I Gaucher disease demonstrated by restriction mapping of the gene.

A cloned fragment of human glucocerebrosidase cDNA has been used as a probe to study restriction polymorphisms in the region of the gene for Gaucher disease. Variability in the size of fragments produced by digestion with the restriction endonucleases Pvu II and Kpn I was discovered. The Pvu II polymorphism was found to be a very prevalent one with a gene frequency of 0.65 for the Pv1.1- allele and 0.35 for the Pv1.1+ allele. Similar frequencies were encountered among diverse ethnic groups. Five of eight Jewish patients with Gaucher disease were found to be heterozygous for the Pvu II restriction polymorphism. One non-Jewish patient with type I Gaucher disease was heterozygous for the Kpn I variant. The existence of Gaucher disease genes in association with either allele of the ancient Pvu II polymorphism clearly indicates that, even within the Jewish population, the Gaucher disease mutation has occurred independently more than once. Presumably, different mutations have also occurred in the non-Jewish population.

Amino Acid Sequence↗
PubMed1985

Molecular cloning and nucleotide sequence of human glucocerebrosidase cDNA.

Mutations in the human glucocerebrosidase gene cause Gaucher disease. A cDNA clone containing the entire human glucocerebrosidase coding region from normal cells has been isolated using lambda gt11 expression libraries. The complete nucleotide sequence, a restriction map, and a hydropathy profile are presented. Hybridization to chromosome-specific DNA localizes the human glucocerebrosidase gene to chromosome 1. The likely precursor protein is 515 amino acids long. The NH2-terminal 19 amino acids constitute a leader sequence that is cleaved from the mature protein. The predicted molecular weight of the mature protein is 55,384, without glycosylation or carboxyl-terminal processing.

Amino Acid Sequence↗
PubMed1985

High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.

The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glucose 6-phosphate. To elucidate the mechanism of accumulation of glucose 6-phosphate when erythrocytes are exposed to high glucose concentrations, hexokinase activity was examined in the presence of naturally occurring inhibitors, such as glucose 1,6-bisphosphate, 2,3-diphosphoglycerate, ADP, and glucose 6-phosphate at physiological concentrations. Without inhibitors or in the presence of glucose 1,6-bisphosphate,2,3-diphosphoglycerate, and ADP, maximum hexokinase activity was observed at 5 mM glucose concentration. On the contrary, in the presence of glucose 6-phosphate, hexokinase activity increased at glucose concentrations greater than 5 mM; inhibition by glucose 6-phosphate was partially competitive with glucose. The relief by glucose of glucose 6-phosphate inhibition of hexokinase is a possible explanation of the increased glucose 6-phosphate level in diabetic erythrocytes.

Diabetes Mellitus↗
PubMed1985

Where does phosphoglycolate come from in red cells?

The hypothesis that human red cells contain activity of ribulose-1,5-diphosphate (Ru-1,5-P2) oxygenase, an enzyme that catalyzes the synthesis of phosphoglycolate, was examined. The putative Ru-1,5-P2 oxygenase was partially purified from human red cells using DE-52 chromatography and (NH4)2SO4 fractionation by monitoring Ru-1,5-P2-dependent 3-phosphoglycerate formation. The synthesis of [32P]phosphoglycolate from [1-32P]Ru-1,5-P2 was attempted in the presence of the partially purified preparation of the provisional Ru-1,5-P2 oxygenase. There was no formation of radioactive phosphoglycolate even under 100% oxygen gas, indicating the absence of this enzyme activity in human red cells. Together with our previous report that glycolate kinase in human red cells is not responsible for the synthesis of phosphoglycolate in vivo, these studies raise the questions whether there is actually phosphoglycolate in red cells as well as whether novel pathways for its synthesis exist.

Diphosphoglyceric Acids↗
PubMed1985

Age-related red cell enzymes in children with transient erythroblastopenia of childhood and with hemolytic anemia.

Red cell enzymes of three children with transient erythroblastopenia of childhood were measured and compared with those of age-matched normal children and children with hemolytic anemia. While the activity of "age-dependent" enzyme such as hexokinase, aldolase, glucose-6-phosphate dehydrogenase, glutamic-oxaloacetic transaminase, and pyruvate kinase were greatly increased in the red cells of children with hemolytic anemia, they were not decreased in the red cells of children with erythroblastopenia of childhood. Only the activity of pyrimidine 5'-nucleotidase was consistently low red cells of these children. These findings are inconsistent with the usual concept that red cell enzyme activities decline throughout red cell life span. Rather, they suggest that there may be very rapid loss in the activity of some red cell enzymes during the first few days of red cell life with little further decline in enzyme activity.

5'-Nucleotidase↗
PubMed1985

Inherited phosphofructokinase deficiency in dogs with hyperventilation-induced hemolysis: increased in vitro and in vivo alkaline fragility of erythrocytes.

Two male English springer spaniel dogs with a chronic hemolytic anemia and sporadic hemolytic crises, historically related to "stress" situations, were studied. Although canine erythrocytes are in general known to be more alkaline fragile, erythrocytes from both patients began to lyse earlier, at significantly lower pH values (near pH 7.4 at 37 degrees C), than erythrocytes from control dogs. Hyperventilation induced by 30 minutes of exercise, placement in a 39 degrees C water bath, or intravenous doxapram increased venous blood pH in dog 1 and control dogs, but transient hemoglobinemia, hemoglobinuria, and severe bilirubinuria occurred only in the studied patient. The erythrocyte phosphofructokinase (PFK) activity was severely decreased in both dogs (10% of controls). The erythrocyte 2,3-diphosphoglycerate content was markedly reduced and the cell chloride content was consequently increased. This change in cell chloride content is related to an increase in the erythrocyte pH, which may partially explain the pathogenesis of hemolysis in canine PFK deficiency. Thus, these studies demonstrate a presumably inherited erythrocyte PFK deficiency in English springer spaniels, which causes an increased in vitro and in vivo erythrocyte alkaline fragility. Dogs with PFK deficiency and inducible hemolytic crises may become a valuable genetic animal model in which to study the pathophysiology of hemolysis.

Anemia, Hemolytic↗
PubMed1985

Limiting role of 6-phosphogluconolactonase in erythrocyte hexose monophosphate pathway metabolism.

The natural product of the glucose-6-phosphate dehydrogenase reaction is 6-phosphoglucono-delta-lactone, which must be hydrolyzed to 6-phosphogluconic acid before it can be further metabolized by 6-phosphogluconate dehydrogenase. Because this lactone is very unstable, it has been uncertain whether the enzyme that hydrolyzes it, 6-phosphogluconolactonase, is required for functioning of the hexose monophosphate pathway. We have purified glucose-6-phosphate dehydrogenase, 6-phosphogluconolactonase, and 6-phosphogluconate dehydrogenase from human erythrocytes to the point where each enzyme is essentially free of each of the other activities. We constructed an artificial hexose monophosphate pathway from these enzymes, providing as substrate 14C-labeled glucose-6-phosphate either directly or by continual generation from 14C-glucose by yeast hexokinase and adenosine triphosphate. The oxidation of 6-phosphogluconic acid was estimated by measuring the CO2 formed. In the absence of a reduced nicotinamide-adenine dinucleotide phosphate (NADPH)-oxidizing system, such as oxidized glutathione (GSSG)-glutathione reductase or phenazine methosulfate, little CO2 was formed, and the presence of 6-phosphogluconolactonase did not affect the amount that was produced. When the hexose monophosphate pathway was stimulated by providing an NADPH-oxidizing system, CO2 was produced two and a half to five times as fast in the presence of 6-phosphogluconolactonase as in its absence. These studies suggest that 6-phosphogluconolactonase is required for the functioning of the hexose monophosphate pathway when the rate of oxidation of NADPH is accelerated.

Carbon Dioxide↗
PubMed1985

Glycolate kinase activity in human red cells.

Human red cells manifest glycolate kinase activity. This activity copurifies with pyruvate kinase and is decreased in the red cells of subjects with hereditary pyruvate kinase deficiency. Glycolate kinase activity was detected in the presence of FDP or glucose-1,6-P2. In the presence of 1 mmol/L FDP, the Km for adenosine triphosphate (ATP) was 0.28 mmol/L and a half maximum velocity for glycolate was obtained at 40 mmol/L. The pH optimum of the reaction was over 10.5 With 10 mumol/L FDP, 500 mumol/L glucose-1,6-P2, 2 mmol/L ATP, 5 mmol/L MgCl2, and 50 mmol/L glycolate at pH 7.5, glycolate kinase activity was calculated to be approximately 0.0013 U/mL RBC. In view of this low activity even in the presence of massive amounts of glycolate, the glycolate kinase reaction cannot account for the maintenance of the reported phosphoglycolate level in human red cells.

Adenosine Triphosphate↗
PubMed1985

Plasma glutathione in health and in patients with malignant disease.

The total glutathione concentration (oxidized plus reduced) of human plasma was investigated. Glutathione was found to disappear when added to plasma, the loss of reduced glutathione being much more rapid than the loss of oxidized glutathione. The glutathione content of plasma from normal humans was found to be 0.91 +/- 0.24 mumol/L (mean +/- 1 SD) when plasma extracts were prepared exactly 10 minutes after the blood had been drawn. The glutathione content of rat plasma was about 15 times as high as that of human plasma. Patients with a variety of malignant disorders were found to have markedly lowered plasma glutathione levels. This did not seem to be associated with chemotherapy or with type of neoplasm. The administration of acetaminophen to rabbits and to human volunteers did not affect plasma glutathione levels.

Acetaminophen↗
PubMed1985

Glucocerebrosidase "processing" and gene expression in various forms of Gaucher disease.

Immunoblots were prepared using extracts of fibroblasts derived from five controls and from four unrelated patients with type I, three with type II, and two with type III Gaucher disease. Five monoclonal antisera and two rabbit sera, crude and affinity purified, were utilized to detect antigen transferred to nitrocellulose paper. Only a band of 63,000 molecular weight (Mr) was consistently detected. We found no 56-K band either in normal or in Gaucher disease fibroblast extracts. Thus, using a variety of antisera, we are unable to verify the claim that the types of Gaucher disease can be differentiated from one another by immunoblotting.

Cell Line↗
PubMed1984

Gd (+) Laguna, a new rare glucose-6-phosphate dehydrogenase variant from Brazil.

A new G6PD variant, designated Gd (+) Laguna, was found in a 9-year-old Brazilian boy of Portuguese ancestry suffering from an iron-refractory anemia. The red cell enzyme activity of the subject was 64%. The mutant enzyme showed slower electrophoretic mobility, increased affinity for glucose-6-phosphate, decreased affinity for NADP+, elevated utilization of substrate analogues, decreased inhibition of NADPH, normal heat stability and a biphasic pH curve. The occurrence of the variant in two non-anemic relatives of the propositus indicates that the association between this G6PD type and anemia may be coincidental.

Adult↗
PubMed1984

Cross-reacting material in Gaucher disease fibroblasts.

Glucocerebrosidase is the enzyme that is deficient in Gaucher diseases. Four monoclonal antibodies reacting with at least two different epitopes of this enzyme have been produced. The amounts of glucocerebrosidase in fibroblasts of patients with all three types of Gaucher disease were investigated by radioiodinating two of the antibodies and measuring their binding to fibroblast extracts immobilized on nitrocellulose filters. The amount of glucocerebrosidase antigen was decreased in all cases of Gaucher disease, particularly in the fibroblasts of patients with the more severe neuronopathic forms of the disorder, types II and III. The catalytic activity was reduced to a greater extent than the amount of antigen in all cases, so that the specific activity of the residual enzyme was found to be diminished. Although measurements in individual cases were quite reproducible and the amount of antigen detected by monoclonal antibodies reacting with different epitopes was quite similar, there was considerable variation between patients. This finding is consistent with the apparent within-type genetic heterogeneity of Gaucher disease, even within the Ashkenazi Jewish population in which it is most prevalent.

Antibodies, Monoclonal↗
PubMed1984

Antileukemic and immunosuppressive activity of 2-chloro-2'-deoxyadenosine.

The adenosine deaminase-resistant purine deoxynucleoside 2-chloro-2'-deoxyadenosine (CdA) is markedly toxic in vitro to nondividing and proliferating normal human lymphocytes and to many leukemia cell specimens. The CdA is also effective against mouse L1210 leukemia in vivo. The present investigations have examined the pharmacology, chemotherapeutic activity, and toxicity of CdA in nine patients with advanced hematologic malignancies refractory to conventional therapy. When administered by continuous intravenous infusion, the deoxyadenosine analog was well tolerated. As monitored by radioimmunoassay, plasma CdA levels rose gradually during the infusions. The CdA was not deaminated significantly. In all patients with leukemia, the CdA lowered the blast count by at least 50%. In one patient with a T-cell leukemia-lymphoma, and in another patient with chronic myelogenous leukemia in blast crisis, the CdA infusion eliminated all detectable blasts from the blood and bone marrow. In a patient with a diffuse lymphoma complicated by severe autoimmune hemolytic anemia, CdA treatment quickly terminated the hemolytic process. Bone marrow suppression represented the dose-limiting toxicity, and was related to plasma CdA levels, cumulative drug dosage, and the rapid release of CdA that accompanied tumor cell lysis.

Animals↗
PubMed1984

Globin-methionine complexes formed during labelling studies.

In implementing globin synthetic measurements using our recently described technique of Cellogel separation of 35S-methionine-labelled globin chain we sometimes encountered aberrant results. We discovered the presence of prominent radioactive bands trailing both the alpha and beta globin chains. Such bands were not present when 3H-leucine served as a label. These bands were not due to contaminants in the 35S-methionine. Their formation could be prevented by including in the incubating mixture 1 mM cystine, cysteine or homocysteine. The bands could not be removed by trichloracetic acid or acid acetone precipitation but did disappear almost entirely after prolonged dialysis against a urea-containing buffer. The trailing bands appear to represent the result of the firm, but not covalent, binding of methionine to globin during the protein synthetic process. Since methionine is commonly used as a label for newly synthesized protein, this phenomenon may be important not only in the investigation of globin synthesis, but also in the study of the synthesis of other proteins.

Chromatography, Thin Layer↗