Increased Lipid Peroxidation of Erythrocytes in Blood Stored in Polyvinyl Chloride Blood Storage Bags Plasticized with Di-[2-Ethyl Hexyl] Phthalate and Effect of Antioxidants

Background and Objectives : Previous work in this laboratory has shown significant decrease in vitamin E in erythrocytes in blood stored in polyvinyl chloride (PVC) bags plasticized with di-[2-ethyl hexyl] phthalate (DEHP), and in erythrocytes incubated in vitro with DEHP. Since vitamin E is a major antioxidant, a study was carried out to find out whether this decrease observed in vitamin E has an effect on lipid peroxidation in blood stored in DEHP-plasticized PVC blood bags. Materials and Methods : Blood was collected in Penpol blood storage bags (which is a DEHP-plasticized PVC bag) and parameters of lipid peroxidation, i.e. activity of superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase, concentration of malondialdehyde (MDA), conjugated dienes, hydroperoxides, glutathione and vitamin E studied in erythrocytes after various periods of storage as compared to glass bottles. Erythrocytes were also incubated in vitro with DEHP with and without vitamin E, and changes in lipid peroxidation studied. Results :Blood stored in Penpol bags showed increased lipid peroxidation in erythrocytes as compared to that stored in glass bottles, as is evident from a greater increase in MDA and a greater decrease in glutathione and a significant decrease in vitamin E. The addition of vitamin E decreased the formation of MDA and conjugated dienes and prevented the decrease in vitamin E. However in spite of increased lipid peroxidation in the presence of DEHP, the release of K⁺ and hemoglobin from erythrocytes was lower. When there was an increase in DEHP taken up by erythrocytes, there was a corresponding decrease in vitamin E. More important, whenever there was an increase in vitamin E in erythrocytes (when RBCs in the presence of DEHP were incubated with vitamin E), there was a progressive decrease in DEHP. Conclusion : DEHP caused increased lipid peroxidation in erythrocytes. At the same time, it decreased the release of K⁺ and hemoglobin from erythrocytes. It is possible that the stabilizing effect of DEHP on the erythrocyte membrane may offset the detrimental effects of the increased lipid peroxidation it causes.     

Modified formulation of CPDA for storage of whole blood, and of SAGM for storage of red blood cells, to maintain the concentration of 2,3-diphosphoglycerate

BACKGROUND AND OBJECTIVES: A dramatic decrease in the level of 2,3-diphosphoglycerate (2,3-DPG) takes place during the storage of whole blood (WB) in CPDA (citrate-phosphate-dextrose-adenine) and a similar decrease occurs during the storage of red blood cells (RBCs) in SAGM (saline-adenine-glucose-mannitol). The aim of the present study was to prevent this decrease by modifying CPDA and SAGM. MATERIALS AND METHODS: The pH of WB anticoagulant or RBC preservative solution was maintained at 7.6 by autoclaving the dextrose solution separately, by incorporating ascorbic acid and nicotinic acid into both CPDA and SAGM (to produce modified CPDA and SAGM solutions), and by reducing the concentration of adenine and adding citrate to the modified SAGM solution. The concentration of 2,3-DPG in WB after 28 days of storage in modified CPDA, and in RBCs stored in modified SAGM, was compared with that in WB or RBCs stored in unmodified solutions. RESULTS: The initial 2,3-DPG levels were maintained after 28 days in the modified formulations [10.63 +/- 2.58 microM/g of haemoglobin (Hb) in the case of modified CPDA and 12.07 +/- 1.47 microM/g of Hb in the case of modified SAGM], whereas in standard CPDA and SAGM solutions, the concentration of 2,3-DPG decreased to very low levels (0.86 +/- 0.97 microM/g Hb for CPDA and 0.12 +/- 0.008 for SAGM). CONCLUSIONS: Our modification in the formulation of CPDA or SAGM is effective in arresting the dramatic decrease in the level of 2,3-DPG that occurs during storage of WB and RBCs in unmodified solutions.     

Lipid peroxidation and hepatic antioxidants in alcoholic liver disease

The generation of hepatic liver peroxidation by free radicals has been proposed as a mechanism for ethanol induced hepatotoxicity. To investigate this hypothesis, lipid extracts from hepatic needle biopsy specimens from alcoholic subjects were examined for evidence of lipid peroxidation by measuring total conjugated dienes by derivative spectroscopy and, after hydrolysis of hepatic lipid extract and reverse phase high performance liquid chromatography, the molar ratio between a diene-conjugated linoleic acid isomer (18:2 (9,11)) and the parent linoleic acid isomer (18:2(9,12)). Changes were related to hepatic histology, iron deposition, glutathione and vitamin E values. Derivative spectroscopy minima suggestive of diene conjugation were identified at 233 and 242 nm and correlated weakly, suggesting these two minima may represent different classes of lipid dienes. There was a weak relation with inflammatory histological changes in the biopsy specimen but no correlation with hepatic iron grade, glutathione, or vitamin E lipid ratio. The proportion of 18:2(9,11) linoleic acid in hepatic lipids correlated significantly with inflammatory histological features and inversely with hepatic glutathione. Furthermore, hepatic glutathione was lower in biopsy specimens with greater iron staining. The ratio of vitamin E to lipid was not related to histological group, inflammation, or iron grade. These findings suggest that excess alcohol consumption leads to hepatic inflammation and lipid peroxidation.     

Peroxidative events in stored platelet concentrates

Changes in metabolic and functional activity of platelets stored as platelet concentrates in plastic bags highly permeable to gases were investigated. The following parameters were measured daily: pH, pO2, pCO2, HCO3, glucose, lactic acid, lactic dehydrogenase, cellular ATP and platelet aggregation induced by different agents (collagen and ADP). As indexes of lipid peroxidative damage, the cellular levels of conjugated dienes, malonyldialdehyde and some antioxidant molecules such as coenzyme Q10 and vitamin E were determined. A marked increase in pO2, conjugated dienes, malonyldialdehyde, lactic acid and lactic dehydrogenase activity was observed during the preservation. Platelet ATP content was unmodified and a remarkable decrease in platelet aggregability was found. pCO2, cyclooxygenase activity, vitamin E, coenzyme Q10, bicarbonate and glucose showed a rapid fall. Our data seem to indicate a preservation of platelet metabolic activity and a correlation between increased lipid peroxidation and functional impairement.     

Decrease in the Concentration of Vitamin E in Blood and Tissues Caused by Di(2-Ethylhexyl) Phthalate, a Commonly Used Plasticizer in Blood Storage Bags and Medical Tubing

Background and Objectives: Significant amounts of di(2-ethylhexyl) phthlate (DEHP) leach into blood stored in DEHP-plasticized PVC bags. The aim of this study was to find out whether DEHP at these low levels has any effect on the concentration of vitimin E, an antioxidant which affords protection against free radical damage. Materials and Methods: DEHP was administered in low doses (150–750μg/100g body weight) to rats intraperitoneally and the concentration of vitamin E in the liver and testes was measured. Concentration of vitamin E was also measured in blood stored in glass bottles in the presence and absence of DEHP and in blood stored in DEHP-plasticized PVC bags. Results: A decrease in the concentration of vitamin E was observed in all cases. Administration of vitamin E to rats and incorporation of vitamin E in the additive solution in the case of blood prevented this decrease. Conclusion: DEHP even at very low doses caused a decrease in the concentration of vitamin E in liver and tests of rats given this substance. Blood stored in DEHP-plasticized bags also showed a decrease in the concentration of vitamin E.     

Oxyhemoglobin dissociation curve and 2,3-diphosphoglycerate in chronic hypoxemia

The measurement of the oxyhemoglobin dissociation curve (ODC) and 2,3-diphosphoglycerate (2,3-DPG) in patients with chronic hypoxemia is important from the view point of tissue oxygenation. However, there have been no consistent results that explain the relation among chronic hypoxemia, 2,3-DPG and P50, which is oxygen pressure at an oxygen saturation of 50 percent. The aim of this study is to clarify what factors affect P50 and 2,3-DPG. 1) Patients with chronic hypoxemia, who showed PaO2 less than 60 Torr, had significantly higher P50 than normal subjects. 2) The concentration of Hb showed significant negative correlation with both P50 and 2,3-DPG. 3) Arterial blood pH showed significant positive correlation with both P50 and 2,3-DPG. 4) In a group with normal levels of Hb and pH, there was significant negative relationship between PaO2 and P50. 5) In a group with normal levels of Hb and pH, there was significant positive relationship between PaCO2 and P50. 6) In a group with normal levels of Hb, pH and PaCO2, there was significant negative relationship between PaO2 and 2,3-DPG. In conclusion, P50 and 2,3-DPG are affected largely by Hb concentration or blood pH, with or without hypoxemia. However there is a mechanism by which P50 and 2,3-DPG are increased by hypoxemia itself in a group with normal levels of Hb, pH and PaCO2.     

Characterization of erythrocyte quality during the refrigerated storage of whole blood containing di-(2-ethylhexyl) phthalate

Di-(2-ethylhexyl) phthalate (DEHP) accumulates in blood brought into contact with materials utilizing this compound as a plasticizer. To determine whether this phthalate diester affects red blood cell integrity, we have compared cell morphology, plasma hemoglobin accumulation, micro-vesicle production, and the concentration of intracellular metabolites and electrolytes of erythrocytes from blood stored at 4 degrees C with and without DEHP. When sufficient emulsified DEHP was mixed with blood to give a final concentration of 300 micrograms/mL, plasma hemoglobin accumulation was reduced by an average of 70%, the percentage of cells exhibiting normal morphology was enhanced by at least 20-fold, and the volume of microvesicles released from red blood cells was reduced by 50% after 35 days of refrigerated storage compared to the values obtained from corresponding samples stored without added phthalate. Similar effects were observed regardless of whether blood was stored in nonplasticized polypropylene or tri-(2-ethylhexyl) trimellitate plasticized polyvinylchloride containers and with DEHP solubilized by a variety of emulsifiers. When 300 micrograms/mL DEHP was added to stored blood containing erythrocytes predominantly in the echinocyte conformation, many of the cells reverted to the normal discoid morphology. The addition of this quantity of DEHP to blood had no significant effect on the course of storage-induced changes in erythrocyte adenosine triphosphate (ATP), 2,3-diphosphoglycerate (2,3-DPG), sodium or potassium concentrations. The data are consistent with the hypothesis that DEHP inhibits the deterioration of the red blood cell membrane that results from the refrigerated storage of whole blood.     

Antioxidant deficit and enhanced susceptibility to oxidative damage in individuals with different forms of alpha-thalassaemia

alpha-Thalassaemia is a common red cell disorder in Taiwan, affecting 6-8% of Taiwanese. Previous studies have shown that reactive oxygen species are generated in increased amounts in thalassaemic red cells. This implies the possible alteration of redox status in thalassaemic patients, which may adversely affect their health. In the present study, the redox status of patients with alpha-thalassaemia trait and haemoglobin H (Hb H) disease was investigated. Lipid peroxidation, as measured by the level of plasma thiobarbituric acid reactive substances (TBARS), was increased in alpha-thalassaemic patients, with the highest level of TBARS in Hb H disease patient. The plasma levels of vitamin A, C, and E were significantly lower in alpha-thalassaemic patients than in controls. The overall antioxidant capacity in plasma was inversely correlated with the severity of alpha-globin gene defect: the more severe the form of alpha-thalassaemia, the lower the overall antioxidant capacity in plasma. Erythrocytes isolated from alpha-thalassaemia patients had lower levels of vitamin E, glutathione, catalase and superoxide dismutase. In addition, these alpha-thalassaemic red cells were more susceptible to hydrogen peroxide-induced lipid peroxidation and decrease in deformability. All these data suggest that the alpha-thalassaemic patients suffer from increased oxidative stress and antioxidant deficit, which may complicate the pathophysiology of alpha-thalassaemia.     

Modulatory role of glutathione monoester in augmenting age-associated neuronal antioxidant system

An ever-increasing number of reports show the involvement of free radicals in the functional and structural changes occurring in the brain as a part of the normal aging process. This study aimed to assess the potential efficacy of glutathione monoester (GME) when administered intraperitoneally (12 mg/kg body weight) for 20 days on memory and the antioxidant defense system and lipid peroxidation in discrete brain regions such as cortex, striatum, and hippocampus of young and aged rats. Age-associated decline in memory and activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione, vitamin E, and vitamin C, and elevated levels of lipid peroxidation and oxidized glutathione, were observed in all the brain regions studied (p < .001). GME administration was effective in restoring the antioxidant status and in decreasing lipid peroxidation level in aged rat brain regions.     

Modulatory Role of Glutathione Monoester in Augmenting Age-Associated Neuronal Antioxidant System

An ever-increasing number of reports show the involvement of free radicals in the functional and structural changes occurring in the brain as a part of the normal aging process. This study aimed to assess the potential efficacy of glutathione monoester (GME) when administered intraperitoneally (12 mg/kg body weight) for 20 days on memory and the antioxidant defense system and lipid peroxidation in discrete brain regions such as cortex, striatum, and hippocampus of young and aged rats. Age-associated decline in memory and activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione, vitamin E, and vitamin C, and elevated levels of lipid peroxidation and oxidized glutathione, were observed in all the brain regions studied (p < .001). GME administration was effective in restoring the antioxidant status and in decreasing lipid peroxidation level in aged rat brain regions.     

The Oxygen Affinity of Haemoglobin E

Oxygen dissociation studies were carried out on haemoglobin E (Hb E) at both high and low haemoglobin concentrations. Oxygen affinities of fresh red cells from three people homozygous for Hb E and from one with Hb E-beta thalassaemia (Hb-E trait/beta-thal trait) were low in three out of four patients studied, while the oxygen affinity of red cells from an individual with Hb-E was normal 2,3-DPG concentration in the fresh cells from the people with homozygous Hb E or Hb-E trait/beta-thal trait which showed low oxygen affinities were elevated sufficiently to account for the shifts observed. When the cells from two of these people with homozygous Hb E were depleted of 2,3-DPG. their oxygen affinities became the same as that of similarly treated normal cells. Pure 'stripped' Hb E in dilute solution behaved identically to Hb A in respect of P50, Bohr shift, haem-haem interaction, and interaction with inorganic phosphate or 2,3-DPG. Hb E, therefore, has the same oxypgen dissociation properties as Hb A both in dilute solution and in the red cell. The low oxygen affinities found in the fresh cells and in whole blood are caused by high 2,3-DPG concentrations within the cell.     

Commercially available blood storage containers

Plastic blood bags improve the safety and effectiveness of blood component separation and storage. Progress towards optimal storage systems is driven by medical, scientific, business and environmental concerns and is limited by available materials, consumer acceptance and manufacturing and regulatory concerns. Blood bag manufacturers were invited to submit lists of the bags they manufacture. The lists were combined and sorted by planned use. The lists were analysed by experts to assess the degree to which the products attend to scientific problems. Specific issues addressed included the use of di‐ethylhexyl phthalate (DEHP) as plasticizer for polyvinyl chloride (PVC) blood bags, the size, material and thickness of platelet bags, and the fracture resistance of plasma bags. Alternatives to DEHP for red blood cell (RBC) storage exist, but are mostly in a developmental stage. Plastic bags (DEHP‐free, PVC‐free) for platelet storage with better gas diffusion capabilities are widely available. Alternatives for plasma storage with better fracture resistance at low temperatures exist. Most RBC products are stored in DEHP‐plasticized PVC as no fully satisfactory alternative exists that ensures adequate storage with low haemolysis. A variety of alternative platelet storage systems are available, but their significance – other than improved oxygen transport – is poorly understood. The necessity to remove DEHP from blood bags still needs to be determined.     

Protective effect of caffeic acid on cardiac markers and lipid peroxide metabolism in cardiotoxic rats: an in vivo and in vitro study

Myocardial infarction affects a large population in the world. Lipid peroxide metabolism plays an important role in the pathology of myocardial infarction. This study aims to evaluate the preventive effect of caffeic acid on lipid peroxides, antioxidants, cardiac marker enzymes, and histopathological findings in isoproterenol (ISO)-induced myocardial-infarcted male Wistar rats. Myocardial infarction was induced in rats by subcutaneous injection of ISO (100 mg/kg) at an interval of 24 hours for 2 days. The ISO-induced rats showed significant increase in the levels of thiobarbituric acid reactive substances, lipid hydroperoxides in the heart, plasma uric acid, and serum cardiac marker enzymes, and significant decrease in the activities of heart superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and the levels of reduced glutathione, vitamin E, and vitamin C in the plasma and heart. Oral pretreatment with caffeic acid (15 mg/kg) daily for 10 days showed significant decrease in the levels of serum cardiac marker enzymes, heart lipid peroxidation products and plasma uric acid and significant increase in the levels of antioxidant system. Histopathology of myocardium also confirmed the protective effect of caffeic acid in myocardial-infarcted rats. In vitro study on total antioxidant activity (2,2'-azinobis-[3-ethylbenzothiazoline-6-sulfonic acid]⁺ assay) confirmed the strong antioxidant action of caffeic acid. Thus, the present study revealed that caffeic acid ameliorates cardiac damage in ISO-induced myocardial infarction by maintaining lipid peroxide metabolism due to its free radical scavenging and antioxidant effects. A diet containing caffeic acid may be beneficial to myocardial infarction.     

Cadmium-induced changes of antioxidant and metabolic status in red blood cells of rats: in vivo effects

Abstract: Chronic exposure of adult rats to dietary untake of cadmium (15 mg CdCl₂/day/kg for 30 days) leads to development of anemia and thrombocytosis. Anemia is characterized by significant reticulocytosis (13.1 ± 1.0%), anysocytosis, poikilocytosis, iron deficiency and marked alterations of antioxidant and metabolic status of red blood cells. Activities of SOD, catalase, GPx and GR were significantly increased in red blood cells of cadmium-treated rats. In treated animals cadmium induced an increase of red cell reduced and oxidized glutathione with no changes of GSSG/GSH ratio. However, significant reduction of lipid peroxidation was found. Plasma levels of tocopherol and ascorbate, as well as activity of glutathione-S-transferase, were all significantly increased in cadmium-treated rats. The energy metabolism of red blood cells was deeply altered in cadmium-treated rats. The levels of ATP, ADP, AMP and TAN were significantly increased while ATP/ADP ratio and adenylate energy charge (AEC) were significantly reduced. The level of 2,3-BPG was somewhat lower, but 2,3-BPG/Hb ratio was considerably higher, in red blood cells of cadmium-treated rats.     

Oxidative stress in the kidney of reproductive male rats during aging

Reproduction alters the male physiology. We performed a comprehensive examination of oxidative stress in the kidneys of male rats with (experienced) or without (naïve) reproductive activity during aging. Oxidative stress was assessed by measuring the activity of catalase, glutathione peroxidase, glutathione S-transferase, and superoxide dismutase, and by measuring protein carbonylation, lipid peroxidation, nitrite and nitrate levels, vitamin C levels, and glutathione (total, reduced, and oxidized forms) levels, and metabolism was accessed by aconitase activity in kidney tissue, as well as testosterone and estradiol levels in serum. Reproductively active animals exhibited increased testosterone levels and altered metabolism. Aging affects tissues and organs and contributes to their functional decline. Elderly naïve rats showed high nitrite and nitrate levels. The experienced rats had less damage in elderly ages, probably because they had higher antioxidant amount and antioxidant enzyme activities at earlier ages, which would have avoided oxidative damage seen in naïve group, and because of the metabolism decline. Glutathione increase in naïve elder rats probably was induced for direct protection against oxidative damage and indirect protection by higher glutathione peroxidase and glutathione S-transferase activities. Linear regression shows that lipid peroxidation levels explained vitamin C levels (B standardized value of 0.42), indicating that vitamin C was properly produced or recruited into kidneys to combat lipid peroxidation. Catalase activity reflected the protein carbonylation and lipid peroxidation levels (B standardized values of 0.28 and 0.48). These results add comprehensive data regarding changes in oxidative stress during aging, and suggest an explanation for the costs of reproduction.     

Inappropriately low red cell 2,3-diphosphoglycerate and p50 in transfused beta-thalassemia

The relationships among hemoglobin concentration (Hb), red cell 2,3- diphosphoglycerate (2,3-DPG), and p50 were studied in 20 chronically hypertransfused patients with thalassemia major. In the nontransfused control group, which included normal individuals as well as patients with sickle cell disease or iron deficiency anemia, the Hb correlated inversely with both 2,3-DPG concentration and p50, as is well established. In contrast, however, prior to transfusion, at the nadir of Hb, patients with thalassemia major had inappropriately low 2,3-DPG concentrations and p50s. These findings occurred in all patients, regardless of whether they had received packed, leukocyte-poor, or frozen-thawed red cells. The hypothesis that the time of blood storage was a factor was excluded by repeatedly transfusing one patient with packed red cells administered within 4 hr of collection in CPDA-1. A second hypothesis, that red cell function might be impaired by the iron- overloaded thalassemic environment, was excluded by studying a newly diagnosed, newly transfused patient with aplastic anemia. In both cases, the same inability to appropriately increase 2,3-DPG and p50 as the Hb fell during the intertransfusion interval was noticed. These data suggest that red cells of chronically transfused patients are unable to adapt to the decline in Hb that occurs during the intertransfusion interval.     

Red Cell 2,3-Diphosphoglycerate Levels in Children with Hereditary Haemolytic Anaemias

The role of red cell 2,3-diphosphoglycerate (2,3-DPG) in increasing the availability of haemoglobin oxygen in neonatal jaundice and hereditary haemolytic anaemias was investigated. Measurements of 2,3-DPG were carried out on 58 normal children and six normal adults, 18 full-term newborns with neonatal jaundice and 57 cases (51 children and six adults) with hereditary haemolytic anaemias. In normal children and adults, with a mean haemoglobin of 12.69 g/dl, mean 2,3-DPG was 14.90 mumol/g Hb. In jaundiced newborns with a mean haemoglobin of 16.04 g/dl mean 2,3-DPG levels were 14.51 mumol/g Hb, i.e. normal. 2,3-DPG levels were increased in patients with beta-thalassaemia major, alpha-thalassaemia, sickle-cell disease, favism, hereditary spherocytosis and in heterozygotes for beta-thalassaemia with increased haemoglobin F. In heterozygotes for beta-thalassaemia with increased haemoglobin A2 only and in sickle cell trait 2,3-DPG levels were normal.     

Glycosylation of hemoglobin in vitro: affinity labeling of hemoglobin by glucose-6-phosphate.

To determine the mechanism for the formation of hemoglobin A1c (Hb A1c) in vivo, we incubated human hemoglobin with glucose and metabolites of glucose. [14C]Glucose-6-phosphate (G6P) reacted readily with deoxyhemoglobin, and formed a covalent linkage. The reaction rate was considerably reduced in the presence of carbon monoxide or 2,3-diphosphoglycerate (2,3-DPG). Purified G6P hemoglobin had a lowered oxygen affinity and decreased reactivity with 2,3-DPG compared to Hb A. G6P behaved as a 2,3-DPG analog and reacted specifically at the NH2-terminal amino group of the beta chain. In contrast, the interaction of hemoglobin with glucose was much slower, and was unaffected by carbon monoxide or 2,3-DPG. Neither glucose-1-phosphate, fructose-6-phosphate, nor fructose-1,6-diphosphate formed a reaction product with hemoglobin. G6P behaves as an affinity label with the phosphate group forming electrostatic bonds at the 2,3-DPG binding site and the aldehvde group reacting with the NH2-terminal amino group of the beta chain. Thus, G6P hemoglobin may be an intermediate in the conversion of Hb A to Hb A1c.     

2,3-Diphosphoglycerate and intracellular pH as interdependent determinants of the physiologic solubility of deoxyhemoglobin S

We have established that 2,3-diphosphoglycerate (2,3-DPG) content and intracellular pH exert separate, but interdependent, effects on the equilibrium solubility (csat) of deoxyhemoglobin S (deoxy-Hb S) that act in concert to modulate intraerythrocytic polymer formation. In a nonphysiologic csat assay system, a steep dependence of csat on pH in the physiologic range 7.0 to 7.6 was shown for both stripped (Hb) and DPG-saturated deoxy-Hb S (Hb-DPG). The solubility-pH profile for Hb under near-physiologic buffer conditions also showed that csat increased steeply in the same pH range (6.8 to 7.6). The effect of 2,3- DPG on csat under near-physiologic conditions was evaluated separately. At pH 7.20, the pH of the human red blood cell, csat values for Hb and Hb-DPG were 19.56 +/- 0.14 and 17.95 +/- 0.45 g/dL, respectively, indicating that the solubility of Hb-DPG is lower than that of Hb by 8.2% +/- 2.3%. Thus, binding of 2,3-DPG in the beta-cleft promotes the polymerization of deoxy-Hb S, the ultimate determinant of cell sickling. Furthermore, because of the abnormal Bohr effect of sickle blood (approximately double that of normal blood), the intracellular pH of deoxygenated sickle erythrocytes should be approximately 0.28 pH unit higher than that of oxygenated cells (ie, 7.41 v 7.13). At the higher pH, the corresponding csat for Hb-DPG is 20.22 g/dL, which is the best estimate of the intrinsic solubility of T-state Hb S under conditions that approximate closely those of pH, temperature, ionic strength, and 2,3-DPG saturation in the fully desaturated sickle erythrocyte.     

The effect of the plasticizer di-2-ethylhexyl phthalate on the survival of stored RBCs

Recent in vitro studies have shown that di-2-ethylhexyl-phthalate (DEHP) inhibits the deterioration of RBCs during refrigerated storage in containers that use this compound as a plasticizer. The experiments described in this report were designed to assess whether this in vitro protective effect of DEHP would result in a prolonged in vivo survival of RBCs infused into normal human recipients. Whole blood collected from ten normal donors was stored for 35 days in citrate-phosphate- dextrose-adenine (CPDA-1) anticoagulant contained in polyvinylchloride (PVC) bags plasticized with DEHP or a trimellitate compound that is known to have low leachability. Aliquots of RBCs from each container were then labeled with chromium-51 and were reinfused into the original donors. For blood stored in DEHP-plasticized PVC bags, 24% more red cells survived in vivo 24 hours after reinfusion than was observed when the blood had been stored in trimellitate-plasticized bags (P less than .001). Whole blood stored in glass bottles showed a similar improvement in in vivo survival when DEHP was added in weekly increments to mimic the accumulation of this plasticizer seen during storage in plastic containers. Survival of packed red cells stored in the presence of DEHP increased by 14% compared with storage in trimellitate-plasticized bags (P less than .05). In agreement with previous studies, hemolysis and microvesicle formation were also reduced in the presence of DEHP. These results suggest that proposed new storage systems lacking DEHP should be carefully evaluated to determine whether adequate post-transfusion survival of RBCs may be achieved.