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Biomedical subjects

M E Ledford

Publications and source records attributed to M E Ledford.

At least 19 recordsLinked to original sources
PubMed1993

In vivo viability studies of two additive solutions in the postthaw preservation of red cells held for 3 weeks at 4 degrees C.

An optimized additive solution was developed for the postthaw preservation of red cells that contained adenine, glucose, disodium phosphate, and citrate buffer. This solution, called AS-17, was compared to AS-3 solution in a clinical trial using 40 subjects (20 in each arm). Fresh-frozen red cells were thawed and deglycerolized after 1 to 18 months and subjected to a second period of storage in either solution for up to 3 weeks at refrigerator temperatures. Both solutions yielded red cells with 24-hour survivals in excess of 75 percent. Cells stored in AS-3 for 21 days had a mean survival of 77 +/- 8 percent and cells stored in AS-17 a mean survival of 79 +/- 11 percent. The AS-17 solution resulted in improved maintenance of pH, p50, and 2,3 DPG compared to that with AS-3, but both solutions appear adequate for 3 weeks of postthaw storage.

2,3-Diphosphoglycerate↗
PubMed1992

Evaluation of methemoglobin formation during the storage of various hemoglobin solutions.

Many researchers are trying to develop a blood substitute based on chemically modified human hemoglobin. In the process of making such solutions, we were faced with the problem of determining the best storage conditions to minimize oxidation of the solutions between the time of manufacture and use. Samples of stroma-free hemoglobin, purified A0 hemoglobin, and various cross-linked hemoglobins were stored for 8-12 months at +4 degrees C -20 degrees C, and -80 degrees C and were analyzed periodically for formation of methemoglobin (MetHb). Various suspending solutions were evaluated for their effects on the rate of MetHb formation, and the approximate rates of MetHb production per month were calculated. Short-term storage of hemoglobin solutions (< 14 days) can be done at +4 degrees C, but extended storage should be done at -80 degrees C with quick thawing. Salts minimize the hemoglobin oxidation during the stress of freeze-thaw operations. Storage at -20 degrees C. presents further problems and should be avoided.

Blood Preservation↗
PubMed1990

Effects of hypertonic saline (7.5%)/dextran 70 on human red cell typing, lysis, and metabolism in vitro.

The introduction of a 7.5% hypertonic saline/6% dextran 70 (HSD) solution into clinical trials for the treatment of hypovolemic states, and the past concerns regarding the possible interference of dextran with blood serology, prompted us to investigate the effects of HSD on human red-cell typing and stability. HSD was evaluated with fresh and 35-day stored CPDA-1 red cells from 12 healthy donors. A 1:5 mixture of HSD to blood in vitro had no effect on ABO, Rh, and MN typing in both fresh and stored blood. HSD produced no significant lysis with fresh cells and a minimal level with stored blood. No evidence of metabolic or morphologic changes was seen after HSD treatment. The results of this study suggest that the clinical use of HSD for the treatment of hemorrhagic shock will not affect blood group determinations or red-cell stability from stored blood which may be infused after the HSD-treated patient is transported to a hospital.

Blood Grouping and Crossmatching↗
PubMed1987

Post-thaw storage at 4 degrees C of previously frozen red cells with retention of 2,3-DPG.

Fresh human blood was collected in CPD, frozen by either the Meryman or the Valeri high glycerol technique, and stored at -80 degrees C. Later the red cells were thawed, deglycerolized by the appropriate technique and resuspended in either saline-glucose wash solution or an additive solution containing ascorbate-2-phosphate, adenine, glucose (dextrose), mannitol and sodium phosphate. The cells were stored at 4-6 degrees C for 21 days and assayed weekly for ATP, 2,3-DPG, pH, P50, glucose utilization and lysis. The additive solution maintained red cell 2,3-DPG at fresh blood levels for 3 weeks and maintained ATP levels sufficiently well to suggest good red cell viability for 21 days. There was no difference in results between the Meryman or the Valeri freezing methods if sodium phosphate was used with the saline-glucose wash solution in the Valeri method. If this additive solution is coupled with sterile deglycerolization techniques, 3 weeks of post-thaw red cell preservation would be practical. Using this additive solution would make frozen blood a reasonable source of red cells for emergency needs in both military and civilian blood banking.

2,3-Diphosphoglycerate↗
PubMed1981

Red cell ATP and 2,3-diphosphoglycerate concentrations as a function of dihydroxyacetone supplementation of CPD adenine.

Units of CPDA-1 whole blood were subdivided and each treated with additions of dihydroxyacetone (DHA) to give final concentrations from 0 to 80 mM. The 'optimum' concentration of DHA to maintain 2,3-diphosphoglycerate (2,3-DPG) with minimal loss of ATP during 42 days of storage appeared to be 30 mM of DHA. With this formulation, red cell 2,3-DPG concentrations rose to 130-140% of normal by 14 days and then decreased in a near-linear manner to 50-60% normal by 42 days, while maintaining adequate ATP levels. In addition, packed red cells were prepared form CPD fresh blood and treated with adenine, glucose, and various concentrations (0-80 mM) of DHA. The cells also responded most favorably to 30mM DHA, although the response was not as positive as whole blood. This concentration of DHA produced nearly 100% maintenance of 2,3-DPG at 14 days with subsequent fall to 30% of normal by 42 days.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

The uptake and egress of adenine from human red blood cells in vitro.

The initial uptake of adenine from plasma by human red blood cells was measured at 0, 10, and 20 C. Initial uptake is completed in several minutes as distribution equilibrium is reached; however, total uptake requires several weeks at 4 C. Adenine inside the red blood cell was shown to egress to the plasma if the equilibrium shifted due to plasma dilution or exchange.

Adenine↗
PubMedDate not supplied

Plasma adenine and cellular ATP in red cell concentrates collected and stored in modified CPD at 4 C.

Eight units of blood were drawn into modified CPD containing 25 per cent higher glucose and 17.3 mg adenine (0.25 mM in blood). Red blood cell concentrates (RCC) were prepared to a mean hematocrit (Hct) of 70, the cells stored at 4 C, and plasma adenine and red blood cell adenosine triphosphate (ATP) were measured weekly for 42 days. The removal of plasma in the preparation of RCC reduced by 39 per cent the available adenine. As a result measurable plasma adenine was depleted by 21 days. The loss of ATP in RCC occurs at a significantly faster rate than in whole blood stored under the same conditions. When red blood cells are stored at higher HCT or for periods longer than 35 days, increased anticoagulant adenine levels are recommended.

Adenine↗
PubMedDate not supplied

The potential use of dihydroxyacetone for improved 2,3-DPG maintenance in red blood cell storage: solution stability and use in packed cell storage.

Dihydroxyacetone (DHA) is effective in maintaining 2,3-diphosphoglycerate (2,3-DPG) concentrations in stored red blood cells. One limitation to the use of DHA is its instability when added to anticoagulant solutions during blood bag manufacture. The stability of DHA solutions have been evaluated. Solutions of DHA are stable at 25 C in water or isotonic saline, with or without the addition of glucose or adenine. DHA is stable to autoclaving; 99 + per cent surviving at 150 mM, and 89 per cent surviving at 1.9 M concentrations. DHA can be incorporated into a satellite addition pouch attached to the main blood drawing bag, and be added to the blood-anticoagulant mixture after phlebotomy or the preparation of red blood cells. Addition of the DHA solution, containing adenine and extra glucose, to packed cells causes significantly improved maintenance of 2,3-DPG during 42 days of 4 C storage, while maintaining adequate concentrations of red blood cell ATP. The use of DHA, adenine, and glucose in extended storage of packed cells, using either zero or seven day addition of the nutrient solution, produces similar efficacious results.

Adenosine Triphosphate↗
PubMedDate not supplied

The in vitro evaluation of modifications in CPD-adenine anticoagulated-preserved blood at various hematocrits.

Erythrocytes stored in the new CPD-adenine anticoagulant (CPDA-1) barely met the 70 per cent 24-hour postinfusion 51Cr recoveries on day 35 when stored at hematocrit greater than or equal to 75 per cent. CPDA-1 differs from CPD in that it has 1.25 times the glucose concentration plus 17.3 mg adenine/63 ml. In an effort to improve the survivability (or viability) of red blood cells following extended storage (35+ days), two new CPD-adenine anticoagulants have been tested in vitro. CPDA-2 and CPDA-3 (both of which contain 34.6 mg/63 ml of anticoagulant or 0.50 mM adenine [final blood concentration], and either 1.75 times or 2.0 times respectively the amount of glucose used in CPD) have been tested for whole blood or red blood cell storage to 42 days. Red blood cell ATP concentrations were better maintained throughout 42 days of storage in both of these formulations than in CPDA-1 at hematocrits that ranged from 40 to 85. Other biochemical parameters (2,3-DPG, pH, plasma hemoglobin) were similar to those of blood stored in CPD or CPDA-1.

Adenine↗
PubMedDate not supplied

Red cell storage for 56 days in modified DPD-adenine. An in vitro evaluation.

The modified CPD-adenine anticoagulants CPDA-2 and CPDA-3 were developed to improve red blood cell storage to 35 days, since CPDA-1 was found marginal at 35 days in high hematocrit samples. In this study red blood cell storage was extended to 56 days. In vitro correlates of viability were monitored to determine the feasibility of evaluating in vivo the ability of CPDA-2 and CPDA-3 to extend storage past 35 days. The data suggest that red blood cells stored up to 56 days may have acceptable viability, providing the possibility of extended storage for the military and certain special civilian situations.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Improved red blood cell storage using optional additive systems (OAS) containing adenine, glucose and ascorbate-2-phosphate.

Red blood cells were treated with optional additive system (OAS) solutions to provide component-specific metabolic enhancement for improved storage. Red blood cell viability, as monitored by ATP concentrations, was maintained by use of adenine and extra glucose. Red blood cell oxygen offloading characteristics were improved by maintenance of red blood cell 2,3-DPG concentrations with ascorbate-2-phosphate (AsP). The use of CPD-collected red blood cells with an OAS containing adenine, glucose, and AsP, or CPD-adenine collected red blood cells with an OAS containing AsP demonstrates the potential to store red blood cells at least 42 days and to maintain red blood cell 2,3-DPG.

2,3-Diphosphoglycerate↗