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Biomedical subjects

G Moroff

Publications and source records attributed to G Moroff.

At least 55 records · Page 3Linked to original sources
PubMed1978

Characterization of human platelet glutathione reductase.

Glutathione reductase (NAD(P)h:oxidized glutathione oxidoreductase, EC 1.6.4.2) has been purified 1000-fold from the cytoplasmic fraction of human platelets. Salts, including the heretofore unreported effect of sodium citrate, activate the NADPH-dependent reduction of oxidized glutathione. Sodium citrate and monovalent salt activation appears to involve multiple sites having different binding affinities. At sub-saturating sodium phosphate, non-linear double reciprocal plots indicative of substrate activation by oxidized glutathione were observed. Initial velocity double reciprocal plots at sub-saturating and saturating concentrations of phosphate generate a family of converging lines. NADP+ is a partial inhibitor, indicating that the reduction of oxidized glutathione can proceed by more than one pathway. FMN, FAD, and riboflavin inhibit platelet glutathione reductase by influencing only the V while nitrofurantoin inhibition is associated with an increase Koxidized glutathione and a decreased V.

Binding Sites↗
PubMed1975

Yeast glutathione reductase. Studies of the kinetics and stability of the enzyme as a function of pH and salt concentration.

1. The pH dependencies of the apparent Michaelis constant for oxidized glutathione and the apparent turnover number of yeast glutathione reductase (EC 1.6.4.2) have been determined at a fixed concentration of 0.1 mM NADPH in the range pH 4.5--8.0. Between pH 5.5 and 7.6, both of these parameters are relatively constant. The principal effect of low pH on the kinetics of the enzyme-catalyzed reaction is the observation of a pH-dependent substrate inhibition by oxidized glutathione at pH less than or equal 7, which is shown to correlate with the binding of oxidized glutathione to the oxidized form of the enzyme. 2. The catalytic activity of yeast glutathione reductase at pH 5.5 is affected by the sodium acetate buffer concentration. The stability of the oxidized and reduced forms of the enzyme at pH 5.5 and 25 degrees C in the absence of bovine serum albumin was studied as a function of sodium acetate concentration. The results show that activation of the catalytic activity of the enzyme at low sodium acetate concentration correlates with an effect of sodium acetate on a reduced form of the enzyme. In contrast, inhibition of the catalytic activity of the enzyme at high sodium acetate concentration correlates with an effect of sodium acetate on the oxidized form of the enzyme.

Acetates↗
PubMedDate not supplied

Aggregation response of human platelets stored at 22 C as platelet-rich plasma.

The aggregating response of human platelets stored at 22 C for 72 hours has been studied. Platelets were stored as platelet-rich plasma in order to maintain the plasma pH essentially constant. The response to ADP and collagen decreased with time, but the decrease was less with relatively high concentrations of the aggregating agents. The response to the ionophore A23187 was essentially unaltered during the storage period. Synergistic aggregation with combinations of ADP, collagen and ionophore A23187 was observed with platelets stored for 72 hours under conditions where singly each of the stimuli caused little or no effect. Stored platelets underwent reversible aggregation over a wide range of ADP concentrations but irreversible aggregation was observed in the presence of nonaggregating concentrations of collagen or ionophore A23187. The inhibition of aggregation by PGE1 or cyclic AMP was facilitated as a result of storage. It is suggested that the decreased response toward ADP and collagen reflects a reduced ability on the part of the platelets to mobilize calcium.

Adenosine Diphosphate↗
PubMedDate not supplied

Characterization of biochemical changes occurring during storage of red cells. Comparative studies with CPD and CPDA-1 anticoagulant-preservative solutions.

Citrate-phosphate-dextrose-adenine (CPDA-1), containing 0.25 mM adenine (final concentration) and 25 percent more glucose than citrate-phosphate-dextrose (CPD), has extended the allowable storage time for red cells to 35 days. Studies were conducted to understand better the characteristics of stored CPDA-1 red cells in relation to the properties of stored CPD red cells. Units with hematocrits near 80 percent showed the following: First, adenosine triphosphate (ATP) and total adenine nucleotide levels of red cells stored with CPDA-1 remained essentially constant during the first 3 weeks of storage after which the levels decreased; with red cells stored with CPD, ATP, and adenine nucleotide, levels were decreased even after 1 week of storage. Second, the pattern of the fall in 2,3-diphosphoglycerate was similar in red cells stored with CPD and CPDA-1. Third, changes in plasma and red cell levels of sodium and potassium, and in plasma ammonia levels, were comparable in CPD and CPDA-1 units; changes in cation levels were most pronounced during the initial 2 weeks of storage. Fourth, hemolysis was much greater in units stored in CPDA-1 for 35 days than in units stored in CPD for 21 days. Fifth, residual glucose concentrations were adequate in units drawn in CPDA-1 and stored for 35 days. We conclude that the changes in the biochemical characteristics of units of red cells stored with CPD and CPDA-1 are similar in most instances with the notable exception of the better maintenance of adenosine triphosphate levels in red cells stored with CPDA-1.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Proposed standardization of methods for determining the 24-hour survival of stored red cells.

Two methods of determining the survival of stored red cells are described: one using a double label and one using a single label. It is not suggested that one is superior, but rather both methods are presented in the hope that the personnel of laboratories engaged in determining the effectiveness of anticoagulant-preservation will follow one of the protocols presented. Were this to occur, many of the interlaboratory variations that have decreased the value of data from red cell survival studies would be decreased.

Anticoagulants↗
PubMedDate not supplied

Survival and biochemical characteristics of stored red cells preserved with citrate-phosphate-dextrose-adenine-one and two and prepared from whole blood maintained at 20 to 24 degrees C for eight hours following phlebotomy.

Studies were conducted to evaluate the characteristics of red cells stored for 35 days following preparation from units of whole blood anticoagulated with citrate-phosphate-dextrose-adenine-one and two (CPDA-1 and CPDA-2) and maintained at 20 to 24 degrees C for 8 hours after phlebotomy. The mean (+/- 1 SD) 24-hour survival for transfused CPDA-1 autologous red cells with hematocrit levels of 78.1 +/- 2.3 percent was 78.0 +/- 8.1 percent (n = 9). The 24-hour survival of red cells from units preserved with CPDA-2 with hematocrit levels of 79.3 +/- 4.5 percent was 74.8 +/- 8.6 percent (n = 15). This difference in survival was not significant. Red cells from control units stored for 1 day showed a 24-hour survival of 91.9 +/- 4.2 percent (n = 7). During the 8-hour holding, red cell adenosine triphosphate levels increased by 15 to 25 percent in units drawn into both CPDA-1 and CPDA-2. After the initial 8-hour period, the red cell 2,3 diphosphoglycerate levels were 54 +/- 12 percent (mean +/- 1 SD) of initial levels in units drawn into CPDA-1 and 58 +/- 8 percent of initial levels in units drawn into CPDA-2. Following 35 days of storage, units of red cells prepared from whole blood drawn into CPDA-1 and CPDA-2 had comparable plasma cation and ammonia levels and similar amounts of cell-free hemoglobin. These data indicate that red cells can be stored satisfactorily for 35 days when prepared from whole blood held at 20 to 24 degrees C for 8 hours.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Reduction of the volume of stored platelet concentrates for use in neonatal patients.

Premature infants and neonatal patients who require platelet transfusions may develop circulatory overload when administered a 50-ml unit of platelet concentrate. We evaluated the influence of centrifugation and resuspension steps used to reduce the volume of stored platelet concentrates on platelet properties by in vitro methods and by determining post-transfusion increments in neonatal patients. In vitro studies were conducted with platelet concentrates stored at 20 to 24 degrees C for 1 and 5 days in CLX (Cutter) and PL732 (Fenwal) containers and for 1 and 2 days in PL146 containers (Fenwal). With platelets stored in any of the three containers, platelet morphology, mean platelet volume, hypotonic stress response, synergistic aggregation, and platelet factor 3 activity were not affected by the processing steps. The centrifugation and resuspension steps did not cause an enhanced discharge of lactate dehydrogenase from platelets. Similar results were obtained when the platelet concentrates were stored on either a flatbed or an end-over-end tumbler agitator. The in vitro platelet recovery following volume reduction was at least 85 percent. In vivo studies were conducted with platelets stored in the PL732 and PL146 containers. Infusion of platelet concentrates after volume reduction produced a mean corrected increment of 18,947 +/- 14,824 when platelets were stored in the PL146 container and 16,178 +/- 15,699 when platelets were stored in the PL732 container. These results indicate that the volume of stored platelet concentrates can be reduced in a manner which maintains platelet properties.

Blood Platelets↗
PubMedDate not supplied

Platelet viability following storage for 5 days. Influence of holding whole blood for 8 hours at 20 to 24 degrees C before concentrate preparation.

Regional blood centers frequently need to hold units of whole blood at 20 to 24 degrees C for several hours after phlebotomy so that sufficient platelet concentrates can be prepared to meet the increasing need. We have evaluated the in vivo viability and in vitro properties of platelets that were prepared from whole blood drawn into citrate-phosphate-dextrose-adenine (CPDA-1) either immediately after phlebotomy or after an 8-hour hold at 20 to 24 degrees C. Platelet concentrates were stored for 5 days at 20 to 24 degrees C in polyolefin containers (PL 732, Fenwal) with end-over-end tumbler agitation. The autologous in vivo recovery (mean +/- SD) and one-half disappearance of 51Cr-labeled platelets prepared immediately after phlebotomy were 44.4 +/- 9.4 percent and 4.0 +/- 0.5 days, respectively. Platelets prepared after the delay of 8 hours showed a recovery of 44.5 +/- 8.4 percent and a one-half disappearance of 4.1 +/- 0.4 days. After 5 days of storage, platelet concentrates showed a mean pH of 7.21 +/- 0.20 when prepared immediately after phlebotomy, and of 7.22 +/- 0.15 when prepared after an 8-hour delay. Mean morphology scores were 280 +/- 33 and 302 +/- 27 for platelets from units prepared immediately after phlebotomy or after a holding period of 8 hours, respectively. Platelets underwent synergistic aggregation after 5 days of storage, independent of the length of time that the units of whole blood were held prior to centrifugation. These studies indicate that platelet concentrates prepared from units of whole blood held initially for 8 hours can be stored for 5 days at 20 to 24 degrees C and survive satisfactorily in vivo and retain in vitro characteristics.

Blood Platelets↗
PubMedDate not supplied

The influence of irradiation on stored platelets.

Platelet concentrates intended for transfusion to immunosuppressed patients are irradiated to minimize transfusion-induced graft-versus-host disease. Because few reports describe how irradiation influences stored platelets, the authors studied whether 5000 rad of gamma irradiation, the maximum dose currently used clinically, altered platelets in vitro. Platelet concentrates were stored for either 1 day or 5 days in plastic (PL 732) containers before gamma irradiation. One unit of a pair of identical platelet concentrates was irradiated; the second unit served as a control. Irradiation did not alter platelet morphology, mean platelet volume, expression of platelet-factor-3 activity, response to hypotonic stress, extent of discharge of lactate dehydrogenase, release of beta-thromboglobulin, formation of thromboxane B2, nor the ability to undergo synergistic aggregation. The lack of any substantial change was observed whether the platelet concentrates were stored initially for either 1 day or 5 days. These results suggest that stored platelets are not altered deleteriously by irradiation with 5000 rad.

Blood Platelets↗
PubMedDate not supplied

Five-week red cell storage with preservation of 2,3 DPG.

The 2,3 diphosphoglycerate (2,3 DPG) content of red cells stored in current anticoagulant-preservative products decreases rapidly after the first few days of storage, and by 3 weeks the red cells are essentially depleted of 2,3 DPG. Because ascorbic acid and ascorbate-2-phosphate (A-2-P) are effective in maintaining erythrocyte 2,3 DPG during liquid preservation, ascorbate was stabilized through autoclaving and subsequent storage by adding it as the trisodium salt of A-2-P to a phosphate-adenine-saline solution at a pH of 8.5 to 9.0. Red cell concentrates prepared from blood drawn into citrate-phosphate-double-dextrose were supplemented with the A-2-P additive solution (AS-4) and studied in vitro and in vivo. Mean 2,3 DPG values for 22 units were 147.6, 113.5, and 82.3 percent of initial value after storage for 3, 4, and 5 weeks, respectively. Maintenance of 2,3 DPG was at the expense of adenosine triphosphate (ATP), which fell to as low as 22.2 percent of initial value after 5 weeks. Despite the low ATP values, the 24 hour 51Cr-labeled red cell recoveries averaged 80.8 and 74.1 percent after 4 and 5 weeks of storage, respectively. The AS-4 system provides a red cell product with acceptable viability and improved oxygen off-loading function.

2,3-Diphosphoglycerate↗