Effects of Irradiation on Red Cells Stored in CPDA-1 and CPD-ADSOL (AS-1)*

Transcription

1 ANNALS OF CLINICAL AND LABORATORY SCIENCE, Vol. 21, No. 3 Copyright 1991, Institute for Clinical Science, Inc. Effects of Irradiation on Red Cells Stored in CPDA-1 and CPD-ADSOL (AS-1)* ELAINE K. JETER, M.D., RICHARD H. GADSDEN, Ph.D., and JOHN CATE, IV, M.D. Medical University of South Carolina Department of Pathology/Laboratory Medicine Charleston, SC ABSTRACT Red blood cells (prbc) collected in citrate, phosphate, dextrose, adenine-formula 1 (CPDA-1) and citrate, phosphate, dextrose-adenine, manitol saline solution (CPD-ADSOL [AS-1]) anticoagulants are increasingly being stored for variable periods in transfusion service inventories following irradiation. W hile anecdotal reports of increased K+ following irradiation and storage have recently appeared in the literature, concom itant in vitro biochemical changes resulting from differences in anticoagulants have not been reported. Utilizing two venipunctures, two units each of 225 ml of blood from five volunteers w ere collected in anticoagulant-adjusted CPDA-1 and AS-1 bags. W ithin two hours of collection, each unit was equally divided. One of each pair was irradiated (2000 rads). Samples were analyzed on Days 0, 1, 3, 7, and every seven days to expiration. Irradiation resulted in a 2.3 fold increase in K+ during the first seven days of storage for both anticoagulants, although significantly greater K+ levels w ere observed in the CPDA-1 pairs compared to the AS-1 pairs. Comparison of glucose utilization, plasma free hemoglobin, 2,3-diphosphoglycerate (2,3- DPG) and lactate dehydrogenase betw een control and irradiated CPDA-1 and AS-1 pairs and betw een anticoagulants were docum ented. Introduction Irradiation of blood and cellular blood com ponents p rio r to transfusion has become an accepted practice to prevent graft-versus-host d isease (GVHD) in im m unodeficient patients,8 and, more recently, in recipients of blood products * Send re p rin t req u ests to E lain e K. Jeter, M.D., A ssistant D irector, T ransfusion M edicine Section, D epartm en t o f Pathology and Laboratory M edicine, M edical U niversity of South C arolina, 171 Ashley A venue, C harleston, SC from first degree relatives.26 W ith the growing dem and for irradiated packed red blood cells (prbc), an increasing num ber of these units have not been transfused to the intended recipient and have been returned to transfusion service inventories for transfusion to a different recipient at a later date. Prior to transfusion, these units have variable shelf lives and undergo changes in the in vitro m icroenvironm ent in both the red cell and the extracellular fluid. W hile, in vitro chemical changes in stored bloodhave been w ell docum ented,6 9, /91/ $01.50 Institute for Clinical Science, Inc.

2 178 JETER, G A D SD E N, A N D CATE only lim ited data are available on the in vitro biochem ical changes in freshly collected irradiated prbc or previously stored prbc, th en irradiated and subsequently stored before utilization. Button et al2 reported no significant difference for m u ltip le analytes in citrate, ph o s phate, dextrose (CPD) anticoagulated whole blood and prbc that were stored for 21 days and irradiated with doses of 5,000, 10,000, or 20,000 rads with sample collection shortly following irradiation. This study used non-paired controls and did not address the issues of chemical changes resulting from prolonged storage subsequent to irradiation. M oore and Ledford10 were the first to report on the in vitro changes in CPDA-1 anticoagulated RBC that were irradiated with 4,000 rads and assayed for m ultiple analytes at designated intervals until expiration. H ow ever, the extracellular potassium concentration (K+) was not among the analytes assayed. Anecdotal reports17,19 of elevated K+ in irradiated, stored prbc, have recently appeared in the literature. Although K+ levels are significantly increased with prolonged storage in irradiated units, in vitro changes resulting from differences in com m only used an tico ag u lants and/or nutritive solutions have not b een investigated. This study docum ents a com prehensive investigation of in vitro effects of 2,000 rads of irradiation on freshly collected p a ire d control and irrad iated prbc at designated storage intervals. It provides a comparison of these in vitro effects w ith regards to two conventionally used anticoagulants, CPDA-1 and CPD-ADSOL (AS-1). M aterials and Methods C o l l e c t i o n a n d M a n i p u l a t i o n o f B l o o d D o n a t i o n s tures from five caucasian male volunteer donors who had not given blood for at least four months. A volume of 225 ml was collected in triple AS-1 system plastic bags* from which one-half of the CPD anticoagulant had been rem oved. An equal volume of 225 ml was collected in quadruple CPDA-1 system plastic bags* following rem oval of one-half of the anticoagulant. Each volume of whole blood was given a unique donor num ber for ease of data collection. Informed consent was obtained as prescribed by the protocol approved by our Institutional Review Board. R outine serologic testing was p erformed and the results were provided to each donor. All ten units were centrifuged at 4994 g t for five m inutes at 4 C. Platelet-poor plasm a (PPP) was rem oved from each unit prior to further m anipulation. An approximate volume of 100 ml of PPP was rem oved from the five CPDA-1 units, yielding a volume and hematocrit in each parent bag of 150 to 160 ml and 60 to 70 percent, respectively. All but approximately 10 to 15 ml of PPP were expressed from the five units collected in CPD, w ith 50 ml of ADSOL preservation so lu tio n ad d ed into th e p a re n t bags. This provided a volum e and h e m atocrit in each parent bag of approximately 150 to 160 ml and 55 to 60 percent, respectively. The contents of each of the 10 units w e re m ix e d a n d e q u a lly d iv id e d betw een the parent bag (controls) and an attached transfer bag (irradiated), and separated. Sterile sample site couplers were aseptically adapted to each bag and all sampling was performed under a laminar flow hood. All units were stored at 1 to 6 C for 42 days. Baseline sampling was obtained within two hours of blood donation. Each of the complimentary transfer bags was irradiated w ith 2,000 rads of A total of 450 ml of whole blood was * p e n w al L aboratories, D eerfield, IL collected with two antecubital venipunc- t RC-3B Sorvall, D upont Co., N ew ton, C T

3 EFFEC T S O F IRRADIATION ON R ED BLO O D CELLS 179 gam m a ir r a d ia tio n.i S am ples w ere obtained from each control and paired irradiated unit at 30 m inutes (Day 0) post irradiation. S ubsequent sam ples w ere obtained on post collection Days 1, 3, 7, 14, 21, 28, 35, and 42. C ultures were obtained on Day 7 and 42, and no growth was observed in all cases after seven days of incubation. After 30 gentle inversions, aliquots of 0.5 m L of re s u s p e n d e d blood w ere obtained in tuberculin syringes, adapted with 16 gauge needles, and placed on ice prior to ph-blood gas analysis, hemoglobin, and hem atocrit determination. Blood was also collected via 10 ml syringes adapted with 16 gauge needles and separated into 5.5 ml and one ml aliquots. The supernatant, collected from the 5.5 ml aliquot after centrifugation at 2,000 g for 15 m inutes, was assayed for N a+, K+, glucose, creatinine, plasm a free hem o globin (PFH), and lactate dehydrogenase (LD). A volume of three ml of eight percent trichloroacetic acid was added to the one m L aliquot, incubated at room tem perature for 10 m inutes and centrifuged for separation of the clear supernatant and sedim ent. The protein free supernatan t for 2,3-D PG d eterm in atio n was im m ediately frozen at -70 C and subsequently assayed in batch mode. R o u t i n e L a b o r a t o r y M e t h o d s The ph, p C 0 2, and p 0 2, were determ in e d by io n - s e le c tiv e e le c tr o d e technology. H C 0 3 and 0 2 saturation w ere calculated values at P50. W hole blood hem oglobin and calculated hem atocrit were determ ined with a q u a n tita t iv e, a u to m a te d h e m a tology analyzer. 1 S upernatant Na +, K +, glucose, and creatinine w ere m easured using a discrete chemistry analyzeru. N a+ and K+ w ere determ ined by ion-selective electrodes. E levated K+ levels w ere reanalyzed by th e sam e m ethod using an appropriate calibration curve. Glucose levels were obtained by a glucose oxidase-oxygen rate m ethod. C reatin in e determ inations w ere m ade using the Jaffe reaction. Supernatant (free) hem oglobin levels w ere d e te rm in e d by the d ifferen tial spectrophotom etric analysis and calculated at delta 415 and 450 nm absorbance. Protein-free supernatants for 2,3-DPG determ in atio n s w ere assayed by the m ethod of Rose and Liebowitz;** the reference interval is 1.6 to 2.6 (xmol per ml. Total lactate dehydrogenase (LD) was determ inated by the modified procedure of Gay, McComb and Bowers, ft Aerobic cultures were performed by a non-radiom etric, autom ated b acterial detection system.tt The data w ere analyzed with paired t test at each assay interval. All significant levels w ere set at a = Results Representative raw data for m ultiple analytes assayed over the storage life of CPDA-1 control and paired irradiated units and AS-1 control and paired irradiated units are shown in table I. This represents analytical data at tim ed intervals for CPDA-1 and AS-1 units collected from one donor via two venipunctures at a single blood donation. Sam ples for analysis in the D ay 0 colum n w ere obtained prior to subsequent irradiation of the resp e c tiv e CPDA-1 and AS-1 t G am m acell 1,000, Atom ic E n erg y o f C anada L im ited, R adiochem ical Co., Kanata, O ntario, C anada. IL 1301, Instrum entation L aboratories, Lexington, MA C o u lte r T -540, C o u lte r C o rp., H ia le a h, F L Astra-8, Beckm an In strum ents, Brea, CA ** Sigm a C hem ical Co., St. Louis, M O t t M onarch 2000, In stru m en tatio n L aboratory, Lexington, MA ti P edi-plus/b actec H PS-660 B ecton-d ickinson D iagnostic In stru m en t System, T ow son, M D

4 180 JETER, G A D SD EN, A N D CATE TABLE I Data From a Single Donor Sample With Designated Anticoagulants Under Experimental Criteria DAY CPDA-1 CONTROL CPDA-1 IRRADIATED ph Na K PFH NA NA DPG LD CPD-ADSOL (AS-1) OONTROL CPD-ADSOL (AS-1) IRRADIATED PH J &28 Na K PFH DPG LD Na+ (mmol/l) K+ (mmol/l) DPG = 2,3 dlphosphoglycerate ( Xmol/mL) NA = not assayed. paired units. Samples collected after 30 m inutes of irradiation w ere not statistically different from the baseline (Day 0) results for all analytes and w ere not in cluded in table I. C reatinine, total hemoglobin and hematocrit were assayed at the designated intervals and provide evidence that the intrinsic conditions within the units did not change (table II). Serial mean K+ for control and irradiated units collected in CPDA-1 and AS-1 RBCs are shown in figure 1. The mean baseline K+ in the CPDA-1 units was 4 mmol per L, while that of the AS-1 units was 1.5 mmol per L. The concentration of K+ in the CPDA-1 and AS-1 irradiated units during the first seven days of storage was approximately 2.3 times greater than the paired controls. However, the CPDA-1 irradiated units had a significantly greater concentration of K+ than the AS-1 irradiated units. From approximately Day 7 until shelf-life expiration the loss of K+ was constant for each anticoagulant. The mean sum of N a+ and K+ for both anticoagulants is shown in figure 2A and 2B. There are no significant differ- PFH = Plasma free hemoglobin (mg/dl) LD = Lactate dehydrogenase (IU/L) ences in the m ean sum of m easured electrolytes betw een the paired CPDA-1 or the paired AS-1 units. However, the sum of N a+ and K+ in the CPDA-1 units was approxim ately 25 mmol per L greater than the sum of m easured electrolytes in the AS-1 units at each interval; a constant effect owing to differences betw een the two anticoagulants. T he standard deviation (SD) for the com bined m easured electrolytes for the CPDA-1 units did not TABLE II Comparison of Hemoglobin, Hematocrit, and Creatinine In paired CPDA-1 and AS-1 Control and Irradiated Units From a Single Donor During Sampling Intervals CPDA-1 CPD-ADSOL (AS-1) Control Irradiated Control Irradiated CRT 1.0 ± ± ± ± 0.07 HCT 67.7 ± ± ± ± 1.4 HGB 22.4 ± ± ± ± 0.3 CRT = Creatinine (mg/dl) HCT = Hematocrit (Percent) HGB = Hemoglobin (mg/dl) (N = 10, Mean ± SD)

5 K* mmol/l EFFECTS OF IRRADIATION ON RED BLOOD CELLS 181 DAYS exceed ±6.8 mmol per L at any sampling interval, and the SD for the AS-1 unit did not exceed ±4.0 mmol per L. Representative ph measurem ents from a single donor are included in table I. There was no significant difference in blood ph betw een the paired control and irradiated CPDA-1 or AS-1 units; how ever, the ph change for the anticoagulants differed significantly over the intervals studied. The m ean values at any sam pling interval are w ithin 0.02 ph units of each other. Baseline ph values for both anticoagulants were slightly less than 7.0. The mean ph of the CPDA-1 units at Day 35 was 6.44, whereas the mean ph of the AS-1 units at Days 42 was The partial pressure of oxygen (p 0 2) was w ell m ain tain ed throughout the shelf-life for all units and provides evidence of viability. The prbc hemolysis data in control and irradiated samples during storage in both anticoagulants are presented in figure 3. Plasm a free hem oglobin (PFH) increased over tim e for all samples. However, hemolysis m easured as PFH was g re a te r in th e irra d ia te d an d n o n irradiated CPDA-1 units compared to AS- 1 units. T he CPDA-1 units show no significant difference betw een control and irradiated units through Day 3 of storage; from Day 7 until expiration, the rate of hem olysis in the irradiated units is significantly greater than the controls. The AS- 1 units show no significant difference betw een the control and irradiated pairs at all sam ple intervals. The m ean concentration of glucose in CPDA-1 and AS-1 paired units is p re sented in figure 4. There was no significant difference betw een the irradiated and control units for each anticoagulant. Glucose utilization was calculated as the difference b etw een glucose concentrations at b a selin e and a g iv en p o stirradiation date. The CPDA-1 control and irradiated units utilized 390 mg per dl and 375 mg per m L of glucose, respectively, after 35 days of storage. The AS-1 control and irradiated units utilized 274 mg per dl and 268 mg per dl of glucose respectively, after 42 days of storage. T he m ean activity of 2,3-DPG in control and paired irradiated cells is shown in figure 5. The baseline mean activity of 2,3-DPG in CPDA-1 and AS-1 units was 2.6 ±.3 (Jimol per ml; 2,3-DPG activity in all units began a significant decline by Day 7 and reached levels less than 0.5 ixmol per ml by Day 28. The CPDA-1 paired units show ed a significant differ-

6 182 JETER, G A D SD E N, A N D CATE Na+ mmol/l K* mmol F i g u r e 2 A. T h e s e data dem onstrate the relative increase and decrease o f K + (mmol p er L) and N a + (m m ol p e r L) for c o n tro l a n d ir r a d ia te d s a m p le s w ith C P D A -1 anticoagulant. T h e sum of K + and N a + is show n. F i g u r e 2 B. T h e s e data dem onstrate the relative increase and decrease o f K + (mmol p er L) and N a + (m m o l p e r L) for c o n tro l a n d ir r a d ia te d sam ples w ith AS-1 anticoagulant. T he sum o f N a + and K + is show n. Na* mmol/l DAYS K* mmol/ DAYS enee (P < 0.025) only on Day 28; there were no significant differences betw een control and irradiated units at other sampling intervals. The AS-1 paired units, show ed no significant differences in control and irrad iated units at any sam p ling interval. The mean LD (IU per L) activity in control and paired irradiated cells for both anticoagulants is p resen ted in figure 6. Baseline LD activity was considerably less than 200 IU per L for all units; at Day 14 LD activity was substantially greater than 200 IU per L for all units. Peak values of approxim ately 1000 IU per L were reached for all units by Day 42. There was no significant difference betw een the CPDA-1 pairs or the AS-1 pairs; how ever, on th e average, th e CPDA-1 units contained approxim ately

7 PFH mg/dl EFFECTS OF IRRADIATION ON RED BLOOD CELLS 183 m m CPDA-1 CTRL CPDA-1 IRRAD AS-1 C T R L AS-1 IRRAD F i g u r e 3. M ean P F H (m g p e r d L ) in p a ir e d CPD A-1 and AS-1 control a n d i r r a d i a t e d u n i ts, r e s p e c tiv e ly. * D a y 42 C PD A -1 u n its w e re not tested for P F H. 50 IU per L greater activity of LD at each sample interval than did the AS-1 units. Discussion 1000 Glucose mg/dl This study provides a comprehensive investigation of in vitro effects of irradiation on freshly collected, irradiated packed red blood cells over the storage life of the cells; a com parison is also m ade of in vitro effects resulting from differences in anticoagulants. D onor venous blood was collected in two different anticoagulants at a single donation, thereby avoiding donor variables resulting from sequential (56 days) whole unit collections. Blood units w ere irra d i ated with 2,000 rads, a dose sufficient to p rev en t transfusion-related GVHD at our hospital. The critical target for radiation within a cell is recognized to be deoxy rib o n u cleic acid (DNA); however, significant perturbations of cell m em branes also occur. Red blood cells, although devoid of a nucleus, are the site of continuous F ig u r e 4. M ean gluc o s e (m g p e r d L ) in p aired CPD A-1 and AS-1 c o n tro l a n d i r r a d ia te d units, respectively. 200

8 184 JETER, G A D SD E N, A N D CATE 2,3-DPG umol/ml 2.5: 1.5' F ig u r e 5. M ean 2,3- D P G (jjlinol p e r m L) in p aired CPDA-1 and AS-1 c o n tro l a n d ir r a d ia te d pr B C. *No m ea su ra b le 2,3 -D P G a c tiv ity w a s o b ta in e d in th e s e sam ples DAYS m etabolic activity. At physiologic tem peratures, red cells m aintain a concentration gradient of cations against th eir environment. In the intact red cell, K+ loss and N a+ gain is tem perature dependent and maximal at 4 c.4,13,23,28 Irradiation leads to increased perm eability to N a+ and K+ by alternating sulfhydryl groups on m em brane surfaces and w ithin red cells.3,21,22 Hem olysis occurs at high irradiation doses.13 Altered electrophoretic m obility of m em brane proteins and glycoproteins, reflecting changes in surface charge, occurs follow ing irradiation.18 Structural m odifications involving peroxidation of unsaturated lipids of the membrane also occur following irradiation.16,27 Shapiro and Kollman21 observed N a+ uptake and K+ loss at 2,000 rads at 20 hours following irradiation nearly double that of the controls. These findings were substantiated by us during the first seven days after irradiation irrespective of the anticoagulant. F or each anticoagulant, LD IU/L F ig u r e 6. M ean L D a c tiv ity (IU p e r L) in p a ire d CPD A-1 and AS-1 c o n tro l a n d ir r a d ia te d units, respectively. DAYS

9 EFFECTS OF IRRADIATION ON RED BLOOD CELLS 185 the K+ loss after the seventh day of storage rem ained constant compared to its respective controls. This would suggest that red cell m em brane irradiation damage progresses for a lim ited num ber of days, after which m em brane repair may occur. The difference in K+ loss betw een anticoagulants is significant (figure 1). This difference is clearly not dilutional; rather it appears to result from the composition of the anticoagulant and/or nutritive-preservative solution. The presence of adenine does not appear to influence potassium shifts during storage;1,24 adenine compounds affect the transport of hydrophilic m olecules across red cell m em branes, and the effect is concentration dependent.7 Since glucose utilization betw een irradiated and non-irradiated units for each anticoagulant was not significantly different, the cation exchange across the membrane would appear to be non-glucose dependent. It has b een shown that electrolyte distu rb an ces after irradiation involve the entrance of N a+ in amounts nearly equivalent to the K+ leaving the cells.5,23 Our data support these findings in red blood cells stored up to 35 and 42 days, respectively. H ow ever, the data suggest that another cation, m ost probably H +, enters the cells; therefore, the N a+ K+ shift is tem perature dependent, and may be ph dependent. The decrease in 2,3-DPG activity in this study is similar to those seen from previous reports.10,12,15 Irradiation did not result in a significant difference in 2.3-DPG levels relative to the controls for either the CPDA-1 units, except on Day 28, or the AS-1 units. Moore, et al11 reported slightly lower 2,3-DPG in adeninecontaining units (C PD vs. CPDA-1). However, when the data were reanalyzed by repeated measures analysis of variance, 2.3-DPG levels in the CPDA-1 units were not significantly different from the CPD u n its.12 Our data suggest, how ever, a slighdy greater decrease in 2,3-DPG in the AS-1 units compared to the CPDA-1 units. Irradiation resulted in an increase in PFH in the CPDA-1 units from Day 7 through the end of storage, with concentrations during this period approximately 20 to 25 percent greater than the controls at the intervals studied. Since no significant difference in PFH in the AS-1 units was observed, the com position of the anticoagulant-nutritive solution may provide a lim ited protective role against ir r a d ia tio n e ffe c t w ith r e s p e c t to PFH increase. Lactate dehydrogenase (LD) activity, to our know ledge, has not b e e n previously studied in irradiated prbcs. There is a constant increase during storage and large amounts are noted at the end of storage; in general, PFH levels parallel LD activity following irradiation and storage. An unexpected finding in this study was the final ph in both anticoagulants. Although no differences were found for b lo o d ph b e tw e e n th e contro l and paired irradiated units for each anticoagulant, the final mean ph in the CPDA- 1 units at Day 35 was 6.44, and 6.3 at Day 42 in the AS-1 units. P ublished data report a ph of 6.6 for CPDA-1 and AS-1 units at Day 35 and 49, respectively.6 Our findings may be related to acid-base shifts reflecting the storage of small volum es of prbc in blood bags w ith gaseous perm eation (unpublished data). The clinical interpretation and applications resulting from this study are not resolved. For blood centers offering red cell irradiation, prolonged storage following irrad iatio n may expose se le c te d patient populations to a significant K+ load following transfusion. Since our data show clear differences in K+ levels over tim e betw een two anticoagulants, the selection of anticoagulant and post irradiation storage period may becom e significant considerations in the transfusion of irradiated red cell products, and may require differing post irradiation storage dates for neonates and adults. In our opinion, our study indicates the need for continued investigation into the effects of

10 186 JETER, G A D SD E N, A N D CATE irradiation on prbc, the role of anticoa g u la n ts in th e m e ta b o lic c h a n g es observed post irradiation, and the clinical significance of metabolic derangements in irradiated blood collected in a variety of anticoagulant solutions. A cknow led g m ents T h e authors w ish to thank Janie R. D ingle and M ary A nn Spivey, M T(ASCP)SBB for m anuscript p re p a ra tio n. T h e te c h n ic a l assista n ce o f A licia F ilz e n, T h o m as W illiam s a n d R achel C rew s is greatly appreciated. R eferences 1. A m b r u s, J. L., A m b r u s, C. M., O d a k e, K., M in k, I. B., Sh ie l d s, R., W a r n e r, W., Bis h o p, C., T r i t s c h, G. L., G o l d e n, G., and M i t t e l - MAN, A.: C linical and experim ental studies in aden in e, various nucleosides and th eir analogs in hem atology. Ann N.Y. Acad. Sci. 255: , B u t t o n, L. N., D e w o l f, W. C., N e w b u r g e r, P. E., J a c o b s o n, M. S., and Ke v y, S.V.: T he effects o f irrad iatio n on b lo o d com p o n ents. T ransfusion 22: , ClV ID A LLI, G.: E ffect o f gam m a irradiation on glucose utilization, glutathione and electrolyte co n ten t o f th e hum an erythrocyte. Radiat. Res. 20: , G l y n n, I. M.: Sodium and potassium m ovem ents in hum an red cells. J. Physiol. 134: , G r e e n, J. W.: T h e s e p a ra tio n o f c a tio n exchange an d glycolysis in hum an red cells exposed to non-ionizing radiations. J. C ellular Com p. Physiol. 47: , H e a t o n, A., M i r ip o l, J., A s t e r, R., D e H a r t, D., H a r t m a n, P., R z a d, L., D a v i s s o n, W., a n d BuCHHOLZ, D. H.: 49 to 56 D a y sto ra g e o f h ig h h e m a t o c r i t r e d c e l l c o n c e n t r a t e s u s i n g ADSOL p r e s e r v a tio n s o lu tio n. T r a n sfu sio n 22:432, J o z w ia k, Z., G w o z d z in s k i, K., and H e l s z e r, Z.: E ffect o f ad en in e n u cleotides and gam m a radiation on th e transport o f tem pol across the e ry th ro c y te m em b ran e. In t. J. R adiat. Biol. 44: , LEITM AN, S. F.: Use of blood cell irradiation in th e p reven tio n of post-transfusion graft-vs-host disease. T ransfusion Sci. 10: , L lm B IR D, T. J. a n d SIL V E R, D.: S e q u e n tia l c h a n g e s in b lo o d p re s e rv e d w ith c itra te - p h o sp h a te-d e x tro se. Surg. G ynecol. O b stet. 238:401^105, M o o r e, G. L. and L e d f o r d, M. E.: Effects of 4000 rad irrad iatio n on th e in v itro storage p ro p e rtie s o f p ack ed re d cells. T ran sfu sio n 25: , M o o r e, G. L., L e d f o r d, M. E., and B r o o k s, D. E.: T h e distribution and utilization of ad e n in e in red blood cells durin g 42 days at 4C storage. T ransfusion 28: , M o o r e, G. L., P e c k, C. C., S o h m e r, P. R., and ZUCK, T. F.: Som e p roperties o f blood stored in anticoagulant CPDA-1 solution. A b rie f sum m ary. T ransfusion 22: , M y e r s, D. K. an d B i d e, R. W.: B iochem ical effects o f x-irradiation on eryth ro cytes. Rad. Res. 27: , O r l i n a, A. R. and Jo s e p h s o n, A. M.: C om parativ e v iab ility o f b lo o d sto red in A C D an d C PD. T ransfusion 9:62-69, P e c k, C. C., M o o r e, G. L., and B o l i n, R. B.: A denine in blood preservation. C RC C rit. Rev. C lin. Lab. Sci. 13: , P u r o h i t, S. C., B is b y, R. H., an d C u n d a l l, R. B.: Structural m odification of h um an erythr o c y te m e m b r a n e s f o l l o w i n g g a m m a - irrad iation. Int. J. Radiat. Biol. 38: , Ra m ir e z, A. M., W o o l f i e l d, D. G., Sc o t t, R., an d M c L a c h l a n, J.: H igh potassium levels in stored irradiated blood. T ransfusion 2 7 : , R e p a c h o l i, M. H., W o o d c o c k, J. P., N e w m a n, D. L., and TAYLOR, K. J. W.: In teractio n of low intensity ultrasound and ionizing radiation w ith the tum or cell surface. Physics M ed. Biol. 16: , R iv e t, C., Ba x t e r, A., and R o c k, G.: Potassium levels in irrad iated blood. T ransfusion 29:185, Sc h e c t e r, D. C. and S w a n, H.: B iochem ical a lte ra tio n o f p re s e rv e d b lo o d. A rch. S u rg. 84: , Sh a p ir o, B. and Ko l l m a n, G.: T h e n atu re of th e m e m b ra n e in ju ry in irra d ia te d h u m an erythrocytes. Rad. Res. 34: , Sh a p i r o, B., K o l l m a n, G., a n d A s n e n, J.: M echanism o f th e effect o f ionizing radiation on sodium uptake by hum an erythrocytes. Rad. Res. 27: , S h e p p a r d, C. W. a n d B e y l, G. E.: C a tio n exchange in m am m alian erythrocytes iii. T h e prolytic effect of x-rays on hum an cells. J. G en. Physiol. 34: , SH IE LD S, C. E.: Effect o f plasm a rem oval on blood stored in A CD w ith aden in e. T ransfusion 22: , SIMON, G. E. and B o v e, J. R.: T h e potassium load from blood transfusion. P ostgrad. M ed. 49:61-64, Sim o n, T. L.: M em orandum to AABB In stitu tional M em bers. Arlington, VA, A m erican Association o f Blood Banks, N ovem ber 6, Sin g e r, S. J. and N ic o l s o n, G. L.: T h e fluid m osaic m odel o f the stru cture of cell m em branes. Science 275: , WALLAS, C. H.: Sodium and potassium changes in b lo o d b a n k sto re d h u m an e ry th ro c y te s. T ransfusion 29: , 1979.