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N L Fortier

Publications and source records attributed to N L Fortier.

35 records · Page 2Linked to original sources
PubMed1978

Fragmentation and myelin formation in hereditary xerocytosis and other hemolytic anemias.

Erythrocytes from a heterogeneous group of hemolytic anemias have been found to release acetylcholinesterase-enriched fragments and show myelin forms during ATP depletion in vitro. The highest amount of fragmentation was found in hereditary spherocytosis and xerocytosis, two inherited membrane defects. Our data suggest ATP depletion plays a role in producing fragmentation or myelin forms. The addition of external CaCl2 1 mM had no effect on the degree of fragmentation. However, propranolol hydrochloride, a cationic anesthetic that does not prevent ATP depletion, inhibited fragmentation and the appearance of myelin forms in both hereditary spherocytes and xerocytes. A more detailed study of the xerocyte fragments showed that they had the same protein composition as those from normal red cells, primarily integral membrane proteins and glycoproteins. The red cells from patients with PNH and G6PD deficiency had the shortest survival in vivo (51Cr) and produced the smallest amount of fragmentation and myelin forms in vitro, whereas xerocytosis with only mild to moderate hemolysis in vivo was associated with the highest amount of myelin forms and membrane fragments in vitro.

Acetylcholinesterase↗
PubMed1977

Partition of catalase and its peroxidase activities in human red cell membrane: effect of ATP depletion.

Partititon of catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase EC 1.11.1.6) and peroxidase (donor:hydrogen-peroxide oxidoreductase EC 1.11.1.7) activities between the red cell membrane and the cytosol were studied under various experimental conditions. A small but significant amount of catalase (1.6%) was retained on human red cell membranes prepared by hemolysing washed red cells with 30 volumes of 10 mM Tris buffer, pH 7.4. Membrane -bound catalase had a relatively higher peroxidase activity than the soluble enzyme fraction. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate of the solubilized membranes demonstrated catalase to be a single band with a molecular weight of 60 000. Membranes prepared from adenosine triphosphate-depleted red cells depicted a two to three-fold increase in catalase activity, as well as an increase in 60 000 molecular weight band on polyacrylamide gel electrophoresis. The extra amount of retained catalase was a less efficient peroxidase than found in fresh membranes. The binding of catalase to ATP-depleted red cell membranes was dependent upon both pH and hemolysing ratio. Red cells incubated at pH 7.1 demonstrated a decrease in bound catalase, as did membranes prepared from red cells hemolysed at 1:100 dilution. beta-Mercaptoethanol decreased the catalase activity in the membranes and increased the odianisidine peroxidase activity without any significant effect on the 60 000-dalton band.

Adenosine Triphosphate↗
PubMed1977

Effect of procaine HCLl on ATP: calcium-dependent alterations in red cell shape and deformability.

Procaine hydrochloric acid, a cationic anesthetic, although unable to prevent the effect of calcium ionophore A23187 on erythrocytes, inhibited the discocyte--echinocyte transformation, increased viscosity, and decreased filterability of red cells undergoing ATP depletion. The effects were abolished by washing ATP-depleted, procaine HCl-treated red cells prior to these determinations. Procaine HCl had no effects on volume, incubated osmotic fragility, or monovalent cation composition of ATP-depleted red cells. The drug increased 45Ca uptake by ATP-depleted red cells but did not change the fraction of membrane-bound calcium. Sodium dodecyl sulfate acrylamide gel electrophoresis of membrane proteins from ATP-depleted red cells revealed formation of high molecular weight protein complexes, which were not formed when biconcave shape and ATP content were maintained by incubation with adenine (0.54 mM) and inosine (12.7 mM); Formation of these complexes was not prevented when the biconcave shape was maintained by procaine HCl. It was concluded that the maintenance of the biconcave shape and normal deformability during ATP depletion by procaine HCl was not related to a displacement of membrane-bound calcium and inhibition of ATP-dependent rearrangement of red cell membrane proteins.

Adenosine Triphosphate↗
PubMed1977

L-Dopa peroxidase activity of human erythrocyte catalase.

The human red cell hemolysate was found to have 3-(3',4'-dihydroxphenyl)-L-alanine (L-dopa) peroxidase activity. During the purification of glutathione peroxidase and catalase by ammonium sulfate precipitation, ion exchange chromatography. Sephadex gel filtration, and preparative polyacrylamide disc electrophoresis, the L-dopa peroxidase activity was found to be associated with catalase. Both sodium azide, 8 mM, and 3-amino-1,2,4-triazole, 50 mM, besides inhibiting catalase, inhibited the L-dopa peroxidase activity in each fraction. Ethylenediamine tetraacetic acid (EDTA), 4 mM, had no effect on catalase or L-dopa peroxidase activity, indicating that the oxidation of L-dopa is not a nonenzymatic process mediated by metal ions. Although the electrophoretic mobility of catalase, L-dopa peroxidase, and glutathione peroxidase are similar, a homogeneous preparation of glutathione peroxidase was free of L-dopa peroxidase activity. L-Dopa peroxidase in human red cells was co-purified with catalase.

Azides↗
PubMed1977

Effect of propranolol on normal human erythrocytes.

The present study was undertaken to standardize the effect of propranolol on normal human red cells and thus establish certain parameters enabling us to evaluate propranolol's effect on pathological cells. Normal human erythrocytes lost 40 MEq. of potassium, decreased the intracellular pH by 0.06 units, and shifted the oxyhemoglobin dissociation curve 6.0 mm. Hg to the right in the presence of propranolol. The series of events and magnitude of the response induced by propranolol was time dependent and sensitive to temperature, pH, drug concentration, and erythrocyte concentration. Calcium was an absolute requirement for maximal propranolol action with simultaneous incorporation of trace amounts of radioactive calcium into the cell. Chelation of calcium with EDTA or EGTA inhibited the response to propranolol.

Calcium↗
PubMedDate not supplied

Availability of the inner surface of the red cell membrane to antibodies in digitonin ghosts. Studies on D-negative cells with anti-D.

Studies were done to determine whether antibodies can detect antigens on the inner red cell stromal membrane. When albumin, anti-A, anti-D, or IgG were combined with varying volumes of intact O, Rh-negative red cells (RBCs), these proteins diluted, on the average, to 76 percent of the total volume, which was almost identical to the volume of the supernatant fluid (mean 77%). In contrast, when the protein markers were combined with packed stroma prepared from O, Rh-negative RBCs by digitonin, they diluted, on the average, to 94 percent of the total reaction volume rather than to the volume of the supernatant (mean 70%). Similar dilution was observed in the fluid volume harvested from stromal suspensions by ultracentrifugation, indicating that the protein markers occupied the total fluid volume of the reaction mixture (inside and outside the stroma). Nonspecific adsorption of the protein markers to stroma did not occur since their dilution was unaffected by doubling the stromal volume and since they could be totally recovered in the fluid harvested by ultracentrifugation. These data indicate that antibodies easily traverse the membrane of RBC digitonin stroma but not the membrane of intact RBCs. Therefore, antibodies may be used to detect antigenic determinants on the inner stromal membrane. When anti-D was incubated with Rh-negative stroma, we did not observe consumption of this antibody. Thus, our data did not indicate that the D antigen is present on the cytoplasmic membrane of Rh-negative RBCs.

Digitonin↗