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Biomedical subjects

E R Burka

Publications and source records attributed to E R Burka.

At least 37 records · Page 2Linked to original sources
PubMed1978

Factor V antibody and disseminated intravascular coagulation.

A factor V inhibitor arose in a 79-year-old man within 1 month of an operation for a fractured leg. Absorption studies with solid-phase antibodies to human immunoglobulins showed the inhibitory activity to be primarily in the IgG class, but also in the IgA class, of immunoglobulins. This is the first report of an IgA immunoglobulin with factor V inhibitory activity. While the inhibitor was present, and at a time when no circulating Factor V activity was detectable, the patient developed septicemia and disseminated intravascular coagulation. The mechanism sustaining disseminated intravascular coagulation despite the absence of circulation factor V activity remains unexplained. The factor V inhibitor disappeared within 5 months of its initial detection. Possible origins of factor V inhibitors are discussed.

Aged↗
PubMed1978

Catabolism of hemoglobin by human erythrocyte membranes.

The role of the human erythrocyte membrane in degrading hemoglobin and hemoglobin subunits was investigated by determined the total radioactivity (cpm) of the nascent alpha and beta globin chains attached to the membrane after labeling of intact cells with 14C-leucine. In conditions characterized by balanced globin synthesis (normal and sickle cell anemia), the total radioactivity of membrane-attached alpha globin is always less than membrane-attached beta globin (alpha/beta = 0.60 +/- 0.10) despite the equal synthesis of alpha and beta chains in the hemolysate. In conditions characterized by unbalanced globin synthesis (alpha-thal and beta-thal traits) the cpm of membrane-attached alpha are also less than those of membrane-attached beta. Attachment of globin chains to the membrane is not related to the net ionic charge of individual chains, but the amount of attachment is related to the relative size of the free intracellular alpha chain pool. The alpha/beta ratio of less than 1 is not due to selective attachment of nascent beta chains or selective destruction of nascent alpha chains. The data indicate that part of the discrepancy between membrane and hemolysate alpha/beta radioactivities seen in the conditions studied is due to different rates of entry into the membrane and catabolism of newly labeled globin polypeptide chains by it.

Anemia, Sickle Cell↗
PubMed1977

The canine erythroid cell system: a new model for study of regulatory mechanism in hemoglobin synthesis.

The total methodology for a new mammalian erythroid cell system which permits direct investigation of the terminal stages of hemoglobin synthesis and assembly is described. The canine system allows quantitative separation of native heme containing alpha and beta chains which recombine to for tetrameric hemoglobin with normal functional properties (n = 2.17). These chains can be utilized for investigation in a cell-free system in which the rates of synthesis of alpha and beta chains are equal (alpha/beta = 0.96 +/- 0.05). Methodology for the quantitative separation of globin allows study of the effects of balanced and unbalanced globin chain synthesis in both the intact cells and the cell-free system.

Animals↗
PubMed1977

Hemoglobin S-O Arab-alpha-thalassemia: globin biosynthesis and clinical picture.

A 22 year old American negro with mild anemia was found to be triply heterozygous for hemoglobin S, hemoglobin O Arab and alpha thalassemia. Hemoglobin A was not detected in the subject's hemolysate. The alpha thalassemia gene was expressed by an alpha/non-alpha synthesis ratio of 0.71 plus or minus 0.07 and was equally rates unbalanced in the peripheral blood and the bone marrow. The total radioactivity of the abnormal chains was equal, indicating equal rates of transcription and translation of the abnormal structural genes. Since the rate of synthesis of betaS and betaO was equal to the proportions of these abnormal chains in the peripheral blood, the abnormal gene products were equally stable. The mildness of the anemia, compared to that of the other reported S-O Arab double heterozygotes, may be due to the moderating influene of the alpha thal gene.

Adult↗
PubMed1976

Lipid synthesis in human erythroid cells: the effect of sickling.

Human reticulocytes are capable of synthesizing membrane lipids from 14C-glycerol de novo. In both sickle and nonsickle reticulocytes the majority of 14C-glycerol was incorporated into phospholipids, primarily phosphatidylserine and phosphatidylcholine. Incorporation into sphingomyelin was minimal. The most abundant neutral lipid synthesized was triglyceride. In the absence of sickling, the rate of lipid synthesis in sickle reticulocytes was similar to that of nonsickle reticulocytes. With the induction of sickling under anoxic conditions sickle reticulocytes showed a prompt increase in the rate of lipid synthesis to an average of 69% above control values, while nonsickle reticulocytes under similar conditions decreased the rate of lipid synthesis. An increase in the rate of membrane lipid synthesis is associated in the mammalian erythroid cell with cell membrane damage. The findings further confirm that lesions of the erythroid cell membrane in sickle cell anemia are secondary to the sickling process itself.

Anemia, Hemolytic, Autoimmune↗
PubMed1976

Decreased life span and membrane damage of carbamylated erythrocytes in vitro.

Red blood cells exposed to cyanate (CNO) in vitro have a concentration-dependent decreased cell survival time associated with an inhibition of the ability of the cell membrane to synthesize lipids. The t1/2 of rabbit erythrocytes exposed to 30 mM or 50 mM cyanate for 1 hr at 37 degrees C is reduced from the normal 24 days to 15 and 9 days, respectively. The cyanate-induced defect in membrane lipid metabolism is irreversible. Carbamylation of membrane proteins and damage to metabolism are minimized by limiting exposure in vitro to 15 mM cyanate at 4 degrees C for 30 min. Cells carbamylated under these conditions do not have a shortened life span. Levels of globin carbamylation of 0.5 moles CNO/mole hemoglobin, shown to be clinically effective in prolonging the life span of sickle erythrocytes, are obtained under these conditions and reach maximal levels after only 30 min of incubation. Carbamylation of blood in CPD anticoagulant is inferior to either ACD or heparin. The findings indicate that adequate carbamylation of sickle erythrocytes with minimal red cell membrane damage can be achieved without significant modification of the standard plasmapheresis procedure utilized by the working blood bank.

Anemia, Sickle Cell↗
PubMed1975

Toxic effect of puromycin on erythrocyte membranes which is unrelated to inhibition of protein synthesis.

Exposure of rabbit or human erythrocytes to concentrations of puromycin as low as 7 x 10(-4)M for 2 hr causes damage to the cell membrane, as evidenced by increased susceptibility of the cells to hyposmotic lysis, increased cell rigidity, and ultrastructural changes consistent with severe membrane damage. Puromycin causes a concentration-dependent internalization of the erythrocyte membrane, resulting in vacuolization of the cells, at concentrations between 7 x 10(-4) M and 10(-2) M. Since the erythrocyte does not synthesize protein, the data indicate that puromycin has a direct toxic effect on erythroid cell membranes which is unrelated to its action in inhibiting the synthesis of protein.

Animals↗