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Biomedical subjects

G L Dale

Publications and source records attributed to G L Dale.

At least 55 records · Page 3Linked to original sources
PubMed1988

Erythrocytes attached to a wheat germ agglutinin coated surface display an altered phospholipid metabolism.

Erythrocytes were bound to a lectin-coated surface; the multivalent attachment to this surface resulted in a severe deformation of the cells and an alteration in the cellular phospholipid metabolism. Human erythrocytes were allowed to bind for 20 min at 20 degrees C to polystyrene beads coated with wheat germ agglutinin (WGA beads). The bound erythrocytes were then lysed to produce stroma bound to WGA beads. Control stroma and stroma-WGA beads were incubated at 37 degrees C with gamma-32P-ATP to examine the phospholipid labeling patterns. The control stroma incorporated 32P-label into phosphatidylinositol-4-phosphate and phosphatidylinositol-4,5-bisphosphate, in agreement with earlier studies. However, the stroma-WGA beads showed incorporation of 32P-label into phosphatidic acid in addition to that in the phosphoinositides. The quantity of 32P-phosphatidic acid produced during the 20-min assay was 3.23 +/- 0.84 (n = 7) picomoles/micrograms stromal cholesterol; the amount synthesized, however, was dependent on the procedure used to prepare the stroma-WGA beads. If the erythrocytes were bound to the WGA beads at 0 degrees C instead of 20 degrees C, the quantity of 32P-phosphatidic acid produced during the subsequent 37 degrees C assay with gamma-32P-ATP was decreased 4.2 fold; the phosphoinositide labeling pattern was unchanged. In addition, when the time for binding of intact erythrocytes to the WGA beads was varied from 1 to 20 minutes, there was a time-dependent increase in the amount of 32P-phosphatidic acid produced. This induction of phosphatidic acid synthesis could not be duplicated with fluid phase WGA. Therefore, the multivalent binding of intact erythrocytes to WGA beads causes an alteration in phospholipid metabolism.

Adenosine Triphosphate↗
PubMed1988

Senescent erythrocytes: isolation of in vivo aged cells and their biochemical characteristics.

Rabbit erythrocytes were covalently labeled with biotin and then infused into the donor animal. Up to 60 days after infusion, the biotinylated cells were selectively isolated by their affinity for avidin. These aged erythrocytes, which are within 10 days of death, were analyzed for several biochemical parameters. The 2,3-bisphosphoglycerate and glutathione levels of these cells were constant with age; however, the adenosine 5'-triphosphate concentrations increased approximately 75% as the cells approached the end of their life span. The activities of several glycolytic enzymes did not change with age.

Adenosine Triphosphate↗
PubMed1987

Biotinylated erythrocytes: in vivo survival and in vitro recovery.

Rabbit erythrocytes were biotinylated by reaction with N-hydroxysuccinimidobiotin; the average level of biotinylation was 25,000 molecules per erythrocyte. These biotinylated cells exhibited a normal survival rate when reinfused into rabbits. Two studies demonstrated that the biotin label was stable in vivo. The first was a double-labeling experiment where the biotinylated erythrocytes were also labeled with 14C-cyanate; on reinfusion, the loss of biotinylated erythrocytes and 14C-cyanate label occurred in unison. The second study demonstrated that biotinylated erythrocytes that had been reinfused into rabbits could later be selectively isolated by attachment to an avidin support. This technique will facilitate a variety of studies that require the ability to label a specific cohort of cells in vitro and then reisolate those same cells after in vivo recirculation.

Animals↗
PubMed1985

Phosphatidylinositol 4-phosphate kinase is associated with the membrane skeleton in human erythrocytes.

Phosphatidylinositol 4-phosphate kinase was eluted from human erythrocyte stroma by three separate and distinct techniques which are known to disrupt the membrane skeleton. In addition, this kinase was found to be associated with the intact skeletons prepared by Triton X-100 extraction of stroma. Phosphatidylinositol 4-phosphate kinase which has been extracted from the membrane is a freely soluble protein with poor enzymatic activity toward added phosphatidylinositol-4-phosphate; however, the enzyme was shown to reassociate with skeleton-depleted stroma and then regain full enzymatic activity toward stromal bound substrate.

Erythrocyte Membrane↗
PubMed1985

Quantitation of megakaryocytopoiesis in liquid culture by enzymatic determination of acetylcholinesterase.

A method has been developed to quantitate megakaryocytopoiesis in culture by measuring acetylcholinesterase synthesized in vitro. Murine marrow cells, treated with diisopropylfluorosphosphate (DFP) to inactivate initial acetylcholinesterase (AchE) present in megakaryocytes and contaminating blood, were set up in Iscove's medium supplemented with 15% DFP-treated horse serum +/- pokeweed mitogen-stimulated spleen cell conditioned medium (PWM-SCM) in 96-well microplates. Following the culture period, Triton X-100, dithiobisnitrobenzoic acid (DTNB), and acetylthiocholine iodide were added to each well. AchE synthesized in culture cleaved acetylthiocholine to thiocholine, which stochiometrically reduced the colorless indicator DTNB to a highly colored product. Thirty minutes following the addition of substrate, the plates were assayed for activity with a vertical recording photometer. When platelets, freshly prepared bone marrow cells, or cultured marrow were assayed by this method, a linear relationship was observed between optical density (OD) and the number of cells assayed. Moreover, a linear relationship between the number of AchE-positive megakaryocytes determined histochemically and AchE activity determined spectrophotometrically was observed. Red cells exhibited no activity. Inhibitor studies demonstrated that the activity measured was true AchE. Separation of marrow by density gradient centrifugation showed that the megakaryocyte enriched fraction contained all the AchE while the megakaryocyte depleted fraction contained none. From the data we conclude that this rapid, semiautomated method quantitates megakaryocytic AchE synthesis in culture, and that this method will be a useful assay system for the detection of factors that influence megakaryocytopoiesis.

Acetylcholinesterase↗
PubMed1985

Quantitation of adenosine-5'-triphosphate used for phosphoinositide metabolism in human erythrocytes.

The human erythrocyte actively phosphorylates and dephosphorylates phosphatidylinositol present in the membrane in an apparent "futile cycle." Recent reports have proposed that this phosphorylation/dephosphorylation cycle is a significant consumer of adenosine-5'-triphosphate (ATP) in the erythrocyte. This study details two independent techniques for quantitating the ATP consumed by this phosphoinositide futile cycle. With the first technique a quasi-steady-state labeling of erythrocyte ATP with 32P-phosphate was obtained, and the rate of synthesis of 32P-phosphoinositides was then monitored. The second technique used a novel labeling strategy that allowed only ATP to be labeled with 32P; the transfer of 32P from ATP to phosphoinositides was then an independent measure of the ATP consumed for phosphoinositide synthesis. These two techniques documented that 0.5% to 1.0% of net ATP produced by the erythrocyte is used for phosphoinositide synthesis.

Adenosine Triphosphate↗
PubMed1985

Peripheral nerve changes following epineurial injection of saline and blood in rat sciatic nerve.

The effects of warm saline and heparinized autogeneic blood injection on a rat sciatic nerve were observed by histologic, histochemic, and CT planimetry. Demonstrable intraneural degenerative changes and epineurial cellular proliferation were present in both groups. Hemosiderin deposits were present in the epineurium and intraneurally only in the blood group. Epineurial saline injection produces nerve damage; therefore, its use for the purpose of neurolysis is not recommended. Further investigations are needed to study the effect of nonheparinized blood injection. The use of computerized planimetry in assessing quantitative nerve damage proved to be feasible.

Animals↗
PubMed1984

Glutathione-dependent protection against oxidative damage of the human red cell membrane.

Glutathione (GSH) dependent protection against oxidative damage of human red cell membrane was examined. An artificial system was used in which chloroform/methanol-extracted red cell lipids, in the form of liposomes, were subjected to attack by a peroxidation system consisting of ascorbate-Fe3+. Human erythrocytes contained a nondialyzable factor, completely inactivated by heating in a boiling water bath for 3 min, which showed GSH-dependent inhibition against lipid peroxidation and was devoid of GSH peroxidase activity. On the other hand, GSH-S transferase, highly purified by affinity chromatography, had no inhibitory activity. These findings strongly indicate that the GSH-dependent protection against lipid peroxidation of human red cell membrane is mediated by one or more proteins other than GSH peroxidase and GSH-S transferase.

Erythrocyte Membrane↗
PubMed1983

The effect of phlebotomy as a treatment of Fabry disease.

Senescent erythrocytes are considered a major source of the ceramide trihexoside which accumulates in Fabry disease patients. We have evaluated weekly phlebotomy as a method to reduce the catabolic load imposed by the senescence of erythrocytes and thereby ceramide trihexoside in one Fabry patient; no change was observed in either plasma or urinary level of ceramide trihexoside. The implications of this observation are discussed with regard to glycolipid metabolism in man.

Bloodletting↗
PubMed1982

Gaucher disease: a century of delineation and research. Enzyme replacement therapy: model and clinical studies.

A number of investigators have attempted to treat Gaucher disease with exogenous glucocerebrosidase. Although at times encouraging biochemical changes and suggestive alterations in organomegaly have been reported, overall, the results of enzyme replacement therapy must be judged to be a failure. In order to understand this lack of success with a promising treatment modality, four aspects of enzyme replacement therapy require examination: 1. The purification of glucocerebrosidase to a form which can hydrolyze glucocerebroside under in vivo conditions; 2. The delivery of the enzyme to cells of the macrophage-monocyte system; 3. The intracellular fate of the administered enzyme; 4. The capacity of the enzyme to effectively contact intracellular glycolipid deposits. A model system for the study of the latter three of these aspects of enzyme replacement therapy has been developed. Monocytes from normal subjects and patients with Gaucher disease were maintained in tissue culture for several months using horse serum-containing culture media. When such cells were "fed" glucocerebrosidase, their enzyme deficiency was corrected for at least 72 hours. Cells from Gaucher disease patients do not spontaneously accumulate glucocerebroside in this system. When loaded with 14C-labeled glucocerebroside, they do not become Gaucher cells but rather manifest a remarkable capacity to catabolize glucocerebroside, so that the labeled fatty acid quickly appears in neutral fats and in phospholipids. Therefore, this model is not yet suitable for study of the effectiveness of enzyme therapy.

Cells, Cultured↗
PubMed1981

Antithrombin III does not have bound glucocerebroside.

Purified antithrombin III has been reported to have bound glucocerebroside, the major glycolipid of plasma. We have separated whole plasma by ultracentrifugation into lipoprotein-rich and lipid-deficient fractions and demonstrated that glucocerebroside and antithrombin III clearly separate into different fractions. Antithrombin III does not have glucocerebroside associated with it.

Antithrombin III↗
PubMed1981

Studies on glutathione transport utilizing inside-out vesicles prepared from human erythrocytes.

Adenosine triphosphate-dependent glutathione transport was characterized using inside-out vesicles made from human erythrocytes. Kinetic analysis of the glutathione disulfide (GSSG) transport showed a biphasic Lineweaver-Burk plot as a function of GSSG concentration suggesting the operation of two different processes. One phase had a high affinity for GSSG and a low transport velocity. Most active at acidic pH and at 25 degrees C, this transport activity was easily lost during the storage of vesicles at 4 degrees C. The Km for Mg-ATP was 0.63 mM; guanosine triphosphate (GTP) substituted for ATP gave a 340% stimulation fo transport activity. Neither dithiothreitol nor thiol reagents affected this transport process. The other phase had a low affinity for GSSG and a high transport velocity. Most active at pH 7.2 and 37 degrees C, this transport activity was stable during storage of vesicles at 4 degrees C for several days. The Km for Mg-ATP was 1.25 mM; GTP substituted with no change in activity. Dithiothreitol increased the V but did not alter the Km, and thiol reagents inhibited the transport. These findings suggest that there are two independent transfer processes for GSSG in human erythrocytes.

Adenosine Triphosphatases↗