Clinical use of blood,blood components and blood products.

The goal of modern transfusion therapy is to provide appropriate replacement therapy with blood components as opposed to whole blood for patients with specific hematologic deficiencies. A prerequisite of component therapy is, therefore, correct identification of the deficiency. Appropriate use of components avoids many of the hazards associated with the use of whole blood, and at the same time makes maximal use of this valuable resource. Blood components separated from whole blood soon after collection and appropriately stored can, in combination, provide all the factors present in fresh whole blood. Red cell concentrates prepared from multiple packs have a hematocrit of approximately 70%. They may be stored for up to 3 weeks at 4 degrees C and are recommended for most situations requiring red cell transfusions. Platelet concentrates, which can be stored for up to 72 hours at 22 degrees C, may be used for thrombocytopenic patients. Fresh frozen plasma, stored plasma, cryoprecipitated factor VIII, factor VIII concentrate and factor IX complex concentrate are available for the proper treatment of patients with hemorrhagic disorders due to coagulation factor deficiencies. Similarly, albumin and immune serum globulin are available for their oncotic and antibody properties respectively. Thus, the availability and appropriate use of the various blood products allows not only optimal transfusion therapy for each patient, but also fuller utilization of national blood resources.     

Separation of blood cells from normal blood and blood of patients with various malignant blood diseases using separation media

Differential counts of normal and leukemic cells separated from human peripheral blood were compared using three different separation media a) Verografin, b) Verografin-Ficoll, c) Isopaque-Ficoll (Lymphoprep), density 1.077 g/ml. In the separation the solution of Verografin (SPOFA) or Verografin-Ficoll yields analogous cell counts to Isopaque-Ficoll solution. The separation of leukemic cells is similar on all three separation media with considerable packing of some cells of the myeloid line. The blood cells separated from peripheral blood of normal donors on three various separation media correlate also in T and B lymphocyte counts, as demonstrated by the results of E and EAC rosette tests.     

Hemoglobin-based blood substitutes and the hazards of blood radicals

Cell-free hemoglobins, chemically altered or genetically expressed in microbial host systems, have been developed as oxygen-carrying therapeutics. Sitedirected modifications are introduced and serve to stabilize the protein molecules in a tetrameric and/or a polymeric functional form. Animal studies, as well as recent clinical studies, have suggested these proteins probably deliver oxygen to tissues. However, concerns still persist regarding the interference of hemoglobin and its oxidation products with the vascular redox balance, potentially impeding its clinical usefulness. This article reviews our current understanding of heme-mediated toxicities and some of the emerging protective strategies used to overcome hemoglobin side reactions.     

Best practices in regulation of blood and blood products

The need for blood regulation arises from the inherent risks of blood transfusion, which are minimized through implementation of standards. Regulatory oversight is advocated by the World Health Organization (WHO) as an essential element of any blood system to ensure such standards are met. The WHO Blood Regulators Network has developed "Assessment Criteria for National Blood Regulatory Systems" that describe the legal authority and functions of a fully competent blood regulator. The core functions include licensing and/or registration of blood establishments, marketing approval of blood products, oversight of all associated substances and devices, control of clinical trials, access to an independent laboratory for product assessments, lot release, and hemovigilance systems. Regulatory policy-making for blood safety is needed to address emerging threats, to consider the risks and benefits of new products and technologies, and to respond to adverse events. Structured policy-making processes are essential to ensure that decisions are science-based, with appropriate consideration of relevant economic and social factors. Decision making is especially challenging in situations of scientific uncertainty, where prudent precautionary measures may be appropriate based on assessments of risk and feasibility of meaningful interventions. There is international interest in finding a common framework for addressing blood safety decisions.     

Hemoglobin-based blood substitutes and the hazards of blood radicals

Cell-free hemoglobins, chemically altered or genetically expressed in microbial host systems, have been developed as oxygen-carrying therapeutics. Sitedirected modifications are introduced and serve to stabilize the protein molecules in a tetrameric and/or a polymeric functional form. Animal studies, as well as recent clinical studies, have suggested these proteins probably deliver oxygen to tissues. However, concerns still persist regarding the interference of hemoglobin and its oxidation products with the vascular redox balance, potentially impeding its clinical usefulness. This article reviews our current understanding of heme-mediated toxicities and some of the emerging protective strategies used to overcome hemoglobin side reactions.     

Potential ratios among blood levels of various blood proteins in the cord blood of healthy newborn infants

The authors have studied the correlations between IgA, IgG, IgM, C3c, C4, alpha 1-AGP and the total proteins, total globulins, alpha 1, alpha 2-globulins in normal newborn cord blood. The results indicate some significant correlations between C3c and C4, C3c, C4 and alpha 1-AGP, C3c, C4, alpha 1 1/2AGP and alpha 2-globulins, C4 and beta-globulins, C3c and alpha 1-AGP. The most significant finding has been inverse correlation between IgA and alpha 1, alpha 2-globulins, total globulins and total proteins.     

Common origins of blood and blood vessels in adults?

After embryonic development, the vast majority of cells are differentiated and all organs are in place. Growth of the organism then ensues and continues until adulthood, whereupon cell division largely ceases. In some tissues, notably the bone marrow, skin, and gut, cell proliferation continues throughout life to replace cells lost by attrition. This regeneration is fueled by rare, long-lived, and largely quiescent stem cells that give rise to committed progenitors, which in turn generate large numbers of fully differentiated cells. Mounting evidence suggests that such cells can significantly contribute to tissue repair and regeneration in adults and may therefore prove beneficial for autologous cell and gene therapies. This review focuses on the potential of adult stem cells to give rise to hematopoietic and vascular cells. We discuss evidence that a highly purified population of adult stem cells, termed SP cells, serves as a hematopoietic progenitor and can contribute to vascular regeneration after injury. We also discuss the potential relationship of these cells to the embryonic hemangioblast.     

Role of potassium in regulating blood flow and blood pressure

Unlike sodium, potassium is vasoactive; for example, when infused into the arterial supply of a vascular bed, blood flow increases. The vasodilation results from hyperpolarization of the vascular smooth muscle cell subsequent to potassium stimulation by the ion of the electrogenic Na+-K+ pump and/or activating the inwardly rectifying Kir channels. In the case of skeletal muscle and brain, the increased flow sustains the augmented metabolic needs of the tissues. Potassium ions are also released by the endothelial cells in response to neurohumoral mediators and physical forces (such as shear stress) and contribute to the endothelium-dependent relaxations, being a component of endothelium-derived hyperpolarization factor-mediated responses. Dietary supplementation of potassium can lower blood pressure in normal and some hypertensive patients. Again, in contrast to NaCl restriction, the response to potassium supplementation is slow to appear, taking approximately 4 wk. Such supplementation reduces the need for antihypertensive medication. "Salt-sensitive" hypertension responds particularly well, perhaps, in part, because supplementation with potassium increases the urinary excretion of sodium chloride. Potassium supplementation may even reduce organ system complications (e.g., stroke).     

Osmotic parameters of red blood cells from umbilical cord blood

The transfusion of red blood cells from umbilical cord blood (cord RBCs) is gathering significant interest for the treatment of fetal and neonatal anemia, due to its high content of fetal hemoglobin as well as numerous other potential benefits to fetuses and neonates. However, in order to establish a stable supply of cord RBCs for clinical use, a cryopreservation method must be developed. This, in turn, requires knowledge of the osmotic parameters of cord RBCs. Thus, the objective of this study was to characterize the osmotic parameters of cord RBCs: osmotically inactive fraction (b), hydraulic conductivity (L_p), permeability to cryoprotectant glycerol (P_glycerol), and corresponding Arrhenius activation energies (E_a). For L_p and P_glycerol determination, RBCs were analyzed using a stopped-flow system to monitor osmotically-induced RBC volume changes via intrinsic RBC hemoglobin fluorescence. L_p and P_glycerol were characterized at 4 °C, 20 °C, and 35 °C using Jacobs and Stewart equations with the E_a calculated from the Arrhenius plot. Results indicate that cord RBCs have a larger osmotically inactive fraction compared to adult RBCs. Hydraulic conductivity and osmotic permeability to glycerol of cord RBCs differed compared to those of adult RBCs with the differences dependent on experimental conditions, such as temperature and osmolality. Compared to adult RBCs, cord RBCs had a higher E_a for L_p and a lower E_a for P_glycerol. This information regarding osmotic parameters will be used in future work to develop a protocol for cryopreserving cord RBCs.     

Direct collection of information during blood donation in blood mobiles

Direct data storage, in the presence of the donor, ensures a realistic reliability and erases any deferred interpretation of the essential information for a good donation identification. Computers can help relieve this restraint. Indeed the evolution of microcomputers (increased capacity and power, decreased weight and volume, and good performance in any use makes them more and more accurate. Associated use of barcodes and microcomputers gives a nonmanual non-human line of words: donor-donation-analysis-blood products-patient. We found, working that way, the following advantages: Information secured. No deferred inputs. Instart comparison of the information on the donor's past history. Accurate donation-donor connection. Such a system represents one more step towards a continuous line of treatment from Donor to Patient in regard of Blood Transfusion Safety.