PubMed · 13748708
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G SCHUBERT. 1961. [Erythrocytes below the "boiling point"].. https://pubmed.ncbi.nlm.nih.gov/13748708/
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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.
Flavonoids and isoflavonoids are potent inhibitors of glucose efflux in human erythrocytes. Net changes of sugars inside the cells were measured by right angle light scattering. The inhibitory potency of hydroxylated flavonoids depends on the pH of the medium. The apparent affinity is maximal at low pH where the molecule is in the undissociated form. The following K(i)-values at pH 6.5 in microM have been obtained: phloretin 0.37+/-0.03, myricetin 0.76+/-0.42, quercetin 0.93+/-0.28, kaempferol 1.33+/-0.17, isoliquiritigenin 1.96, genistein 3.92+/-0.62, naringenin 8.88+/-1.88, 7-hydroxyflavone 17.58+/-3.15 and daidzein 18.62+/-2.85. Flavonoids carrying hydroxyl groups are weak acids and are deprotonated at high pH-values. From spectral changes pK-values between 6.80 (naringenin) and 7.73 (myricetin) have been calculated. No such pK-value could be obtained from quercetin which was rather unstable at alkaline pH. Flavone itself without a hydroxyl group does not demonstrate any absorbance changes at different pH-values and no significant change in inhibition of glucose transport with pH (K(i)-value around 35 microM). In this respect it is similar to the antiestrogens diethylstilbestrol, tamoxifen and cyclofenil with K(i)-values for glucose efflux inhibition of 2.61+/-0.30, 6.75+/-2.03 and 3.97+/-0.54 microM. Except for phloretin, the flavonoids investigated have planar structures. The inhibitory activity in glucose efflux of planar flavonoids increases exponentially with the number of hydroxyl groups in the molecule.
Reconstruction of cell-scale metabolic networks is now possible. A description of allowable metabolic network functions can be obtained using extreme pathways, which are the convex basis vectors of the solution space containing all steady state flux distributions. However, only a portion of these allowable network functions are physiologically possible due to kinetic and regulatory constraints. Methods are now needed that enable us to take a defined metabolic network and deduce candidate regulatory structures that control the selection of these physiologically relevant states. One such approach is the singular value decomposition (SVD) of extreme pathway matrices (P), which allows for the characterization of steady state solution spaces. Eigenpathways, which are the left singular vectors from the SVD of P, can be described and categorized by their biochemical function. SVD of P for the human red blood cell showed that the first five eigenpathways, out of a total of 23, effectively characterize all the relevant physiological states of red blood cell metabolism calculated with a detailed kinetic model. Thus, with five degrees of freedom the magnitude and nature of the regulatory needs are defined. Additionally, the dominant features of these first five eigenpathways described key metabolic splits that are indeed regulated in the human red blood cell. The extreme pathway matrix is derived directly from network topology and only knowledge of Vmax values is needed to reach these conclusions. Thus, we have implemented a network-based analysis of regulation that complements the study of individual regulatory events. This topological approach may provide candidate regulatory structures for metabolic networks with known stoichiometry but poorly characterized regulation.