In 23 hemodialyzed patients the metabolic defect of erythrocytes related to uremia and potentiated by dialysis was studied to establish a possible link with the shortened erythrocyte survival. A highly significant correlation was found between sulfhemoglobin provoked by oxidative stress and erythrocyte rigidity measured by filterability. Impaired filterability also correlated with the degree of splenic sequestration. Both sulfhemoglobin and impaired filterability correlated with the degree of hemolysis. Finally, erythrocyte survival showed a highly significant correlation with the degree of anemia. From osmotic fragility, plasma trapping, erythrocyte ATP and 2,3-diphosphoglycerate (DPG), and serum phosphorus, calcium, and magnesium measurements it seems unlikely that either spheric transformation or sol-gel transformation of the membrane is causing the increased erythrocyte rigidity. In view of the impaired erythrocyte defense capacity against oxidative injury, cell content rigidity as mediated by reduced hemoglobin solubility is a more likely explanation. Our results give a rational basis for a trial of splenectomy in severely anemia hemodialyzed patients.
The prevention of enterogenic infection by human lactoferrin was tested in five neutropenic patients receiving chemotherapy for acute myelogenous leukemia. Lactoferrin did not significantly delay the onset of infection but reduced its duration and severity as judged from the course of fever. Compared with nine matched controls, lactoferrin-treated patients had a lower incidence of bacteremia on the whole and of gram-negative bacteremia in particular.
Oxidative iodination of human lactoferrin (Lf) as commonly performed by using the chloramine-T, the Iodogen or the lactoperoxidase method produces an unreliable tracer protein because of excessive and heterogeneous polymer formation. Before iodination a minor tetramer fraction may be demonstrable in iron-saturated Lf only. Iodination-induced polymerization of iron-poor as well as iron-saturated Lf occurs independently of the presence or absence of 10 mM-EDTA and the 125I-/Lf molar ratio used for iodination. 125I-Lf polymers are mainly covalently linked, as suggested by the lack of substantial dissociation in SDS/polyacrylamide-gel electrophoresis. Damage to the 125I-Lf monomer may be another consequence of oxidative iodination. This is demonstrated in SDS/polyacrylamide-gel electrophoresis where 50% of the radioactivity of apparently normal monomer (Mr 75,000) is displaced to a lower-Mr region (30,000-67,000) after reduction with dithiothreitol. Non-oxidative iodination by the Bolton-Hunter technique produces an antigenetically stable tracer that is not being subjected to polymerization and monomer degradation as judged by high-performance gel chromatography and SDS/polyacrylamide-gel electrophoresis with and without dithiothreitol treatment. It is concluded that oxidation in itself leads to covalent non-disulphide cross-linking between human Lf molecules and, possibly, to intramolecular peptide-bond breaking becoming unmasked under reducing conditions. In biological experiments with human 125I-Lf this problem should be carefully considered.
The mutant Hb P Galveston (beta117His leads to Arg) is observed in two heterozygotes for beta thalassemia and by itself does not cause clinical symptoms. Some of the physico-chemical properties of Hb P Galveston are identical to the onemical properties of Hb P Galveston are identical to the ones hemoglobin Zurich (beta 63 His leads to Arg) so that only a detailed analysis led to its proper identification.
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