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J Palek

Publications and source records attributed to J Palek.

141 records · Page 8Linked to original sources
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Red cell membrane protein phosphorylation in hemolytic anemias and muscular dystrophies.

We review our current understanding of membrane phosphorylation in normal and abnormal erythrocytes. The major phosphoproteins in red blood cell (RBC) membranes are spectrin (band 2), bands 3, 2.1, and 4.5, and glycophorin A. At least two protein kinases can be distinguished on the basis of their stimulation by cyclic AMP and salt; they are present both in the membrane and in the cytosol. Analysis of the conflicting data on endogenous membrane-protein phosphorylation in abnormal RBCs indicates a considerable variability of phosphorylation rates which largely depends on the manner of preparation of ghosts and enzyme assay conditions. This variability reflects differences in the partitioning of protein kinases between the membrane and cytosol, the specificity and accessibility of membrane-protein substrates, and reaction kinetics. We select examples of data from several hemolytic anemias to illustrate that precautions are needed to interpret abnormalities of membrane-protein phosphorylation properly; we discuss possible new methodological approaches.

Actins↗
PubMedDate not supplied

Does a patient with hereditary spherocytosis qualify for preoperative autologous blood donation?

BACKGROUND: Hereditary spherocytosis (HS) is characterized by osmotically fragile spherocytic red cells (RBCs), mild to moderate hemolysis, and splenomegaly. Little is known about the safety of blood bank storage of HS RBCs. CASE REPORT: A 50-year-old man with mild autosomally dominant HS asked to make an autologous RBC deposit before his scheduled surgery. His RBCs were serially tested for osmotic fragility during 4 weeks of blood bank storage in CPD with adenine-saline. Aliquots of his fresh and 4-week-old RBCs were also labeled with 51Cr for measurement of in vivo survival. The osmotic fragility of the patient's fresh RBCs was normal, with 50-percent hemolysis at approximately 0.43-percent NaCl and a sigmoid lysis curve. Incubated osmotic fragility (24 hours at 37 degrees C) was abnormal, with 50-percent hemolysis at 0.64-percent NaCl. Median survival of his fresh 51Cr-labeled RBCs was moderately shortened at 17.5 days. Osmotic fragility increased during storage, with 50-percent lysis occurring at 0.58-percent and 0.62-percent NaCl after 2 and 4 weeks, respectively. Volunteer normal donor RBCs exhibited 50-percent lysis in 0.48-percent NaCl after 4 weeks. Median survival of the patient's 4-week-old 51Cr-labeled RBCs was severely shortened, at 3.5 days. At surgery, intraoperatively salvaged RBCs demonstrated osmotic fragility identical to that of the patient's RBCs freshly obtained by venipuncture. CONCLUSION: HS RBCs may lose membrane under optimum storage conditions, becoming unsuitable for transfusion at surgery. Intraoperative autologous transfusion may be preferable to preoperative deposit for avoidance of allogeneic RBC transfusion in patients with HS.

Anion Exchange Protein 1, Erythrocyte↗