PubMed · 13176560
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A N VERVEEN. 1954-05-22. [A chromocytometer].. https://pubmed.ncbi.nlm.nih.gov/13176560/
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BACKGROUND: A minority of blood donors are Rh(D)-negative, and Rh(D)-negative red blood cell (RBC) products are often overutilized. As such, Rh(D)-negative RBCs may be difficult to maintain in blood bank inventory. STUDY DESIGN AND METHODS: We changed our blood bank laboratory policy to approve non-alloimmunized Rh(D)-negative patients to receive Rh(D)-positive RBCs for routine transfusion under defined criteria. Those criteria included Rh(D)-negative males (all ages) and females (aged >50 years) who were designated as do not resuscitate (DNR), either with or without intubation, in the electronic medical record. RESULTS: From August 15, 2024 through August 15, 2025, a total of 204 Rh(D)-negative patients met the above criteria and were approved to receive routine Rh(D)-positive RBC transfusions. Within that group, 23 patients received Rh(D)-positive RBCs. The remaining patients either did not require transfusion or were issued Rh(D)-negative RBC units. Since implementing this practice, a total of 68 Rh(D)-negative units were conserved during this time frame. Notably, 28 of the 68 units (41%) were type O, Rh(D)-negative. DISCUSSION: Rh(D)-positive RBCs can be routinely given to non-alloimmunized Rh(D)-negative patients who are not at risk for developing hemolytic disease of the fetus and newborn (HDFN). By creating clear guidelines for the routine administration of Rh(D)-positive RBCs to patients who are not at risk for HDFN, the inventory of Rh(D)-negative RBC units can be directed to those patients who would most benefit from this limited resource.
Human erythrocytes are highly specialized cells whose function is oxygen transport. These cells' sole metabolic source of energy is the fermentation of glucose via glycolysis. They contain an active insulin receptor and respond to insulin by increasing phosphorylation of tyrosine residues in several proteins. However, no metabolic effects have yet been associated with activation of this receptor in human erythrocytes. Here, we show that insulin increases the rate of glycolysis in human erythrocytes. Lactate production increased 56 and 173% in the presence of 10 and 100 nM insulin, respectively. A higher insulin concentration (1000 nM) partially reversed the stimulation of glycolysis. These effects occur through activation of the key glycolytic enzyme 6-phosphofructo-1-kinase, which exhibits the same pattern of modulation by insulin as seen for glycolytic flux. This modulation also occurs physiologically since ex vivo experiments revealed 50% stimulation of 6-phosphofructo-1-kinase (PFK) activity following a high carbohydrate meal. Insulin increases phosphorylation of PFK and redistributes the enzyme in red blood cells, causing it to detach from the erythrocyte membrane: upon insulin stimulation, the amount of enzyme associated with the plasma decreases by 86%. Detachment is a common mechanism of enzyme activation. As a consequence, insulin prevents up to 68% of red cells hemolysis. These results show that insulin regulates erythrocyte glycolysis and viability and suggest that this regulation is associated to other erythrocyte functions such as oxygen transport. Finally, we suggest that this regulatory mechanism might be compromised in patients with diabetes mellitus.
The bacterial lipopeptide iturin A is able to cause hemolysis of human erythrocytes in a dose-dependent manner. Hemolysis takes place at iturin concentrations below its critical micellar concentration. Relative kinetics determinations clearly show that K(+) leakage occurs prior to hemoglobin release. Furthermore, hemolysis can be prevented by addition to the outer solution of osmotic protectants of appropriate size. Altogether these results indicate that iturin A-induced hemolysis follows a colloid-osmotic mechanism, with the formation of a membrane pore of average diameter 32 A. Iturin A is capable of inducing leakage of an aqueous fluorescent probe trapped in human erythrocyte ghosts, but not in large unilamellar liposomes made of various lipid compositions. The different permeabilizing effects of iturin A on model and biological membranes are discussed on the light of the presented results.