Effects of centrifugal and roller pumps on survival of autologous red cells in cardiopulmonary bypass surgery

Background: Either a roller pump or a centrifugal pump can be used in the extracorporeal circuit during surgery with cardiopulmonary bypass. In this study, we assessed the effect of these two pumps on the 24-h post–transfusion survival values of autologous red blood cells (RBC). Study design and methods: Fourteen male patients subjected to extracorporeal bypass procedures were studied. In seven patients, the autologous red cells were collected following the cardiopulmonary bypass procedure using the roller pump, and in seven patients, autologous red cells were collected following the cardiopulmonary procedure using the centrifugal pump. The 24-h post–transfusion survival values of the autologous RBC were measured using the 51 disodium chromate/99m technetium double isotope procedure. The effects of the extracorporeal bypass procedures using the roller pump and the centrifugal pump were also assessed by the measurements of hematocrit, platelet count, plasma hemoglobin, and serum lactate dehydrogenase levels. Results: The 51 disodium chromate 24-h post–transfusion survival values of the autologous RBC were similar whether the roller pump or the centrifugal pump was used in the extracorporeal circulation, as were the hematocrit, platelet count, plasma hemoglobin and serum lactate dehydrogenase levels. Conclusion: The 24-h post–transfusion survival values of autologous RBC, measured by the 51 disodium chromate/99m technetium double isotope procedure, were not significantly different, whether the roller pump or the centrifugal pump was used in the extracorporeal circuit using membrane oxygenators during cardiopulmonary surgical procedures.

Exploring the feasibility of selective depletion of T lymphocyte subsets by whole blood immunoadsorption cytapheresis

Normal turnover of T lymphocytes is slow relative to other blood cells. Consequently, the physical removal of circulating leucocytes by thoracic duct drainage, repeated leukapheresis or blood filtration results in T cell depletion and immunosuppression. However, clinical use of such procedures is impractical compared with immunosuppressive drugs or radiation. None the less, immunosuppression by physical depletion of T cells, avoiding the systemic toxicities of drugs and radiation, might have clinical advantages if immunophenotypically distinct T cell subsets could be depleted selectively. Recent advances in targeted plasma protein apheresis using adsorbent macrobead columns prompted us to determine whether analogous techniques might permit CD4+ T lymphocytes to be removed selectively from whole blood. To explore this possibility, we linked murine anti-human-CD4 and isotype-identical control monoclonal antibodies (mAbs) to agarose, polyacrylamide and polystyrene macrobeads (150-350 microm) and then evaluated the selectivity, specificity and efficiency of macrobead columns to remove CD4+ T cells from anti-coagulated whole blood at varying mAb densities and flow rates. We also examined saturation kinetics and Fc-oriention versus random coupling of mAbs to macrobeads. Sepharose 6MB macrobead (250-350 microm) columns proved to be most effective, selectively removing up to 98% of CD4+ T cells from whole blood. Moreover, depletion efficiency and selectivity were retained when these columns were reused after elution of adherent CD4+ cells. These studies indicate that selective depletion of T lymphocyte subsets by whole blood immunoadsorption apheresis using mAb-linked macrobead columns may be feasible on a clinical scale. It is possible that such apheresis techniques could achieve targeted forms of immunosuppression not possible with drugs or radiation.

Expired Liquid Preserved Platelet Releasates Retain Proliferative Activity1

BACKGROUND

Donated platelets for clinical use currently have a shelf life of 5 days as the result of possible bacterial contamination and loss of hemostatic function. Platelet releasates contain multiple growth factors that have been shown to accelerate wound healing. We sought to demonstrate that although expired platelets can no longer sustain hemostasis, they serve a longer term role as a reservoir of growth factors that could be harnessed in wound healing applications.

MATERIALS AND METHODS

Liquid preserved human platelets were activated from 1 to 21 days after collection using zeolite and were then analyzed for their ability to stimulate human fibroblast proliferation, which is an in vitro serogate of growth factor activity and wound healing potential. Total protein content, the concentration of platelet-derived growth factor (PDGF) and transforming growth factor-beta were also measured.

RESULTS

Activated liquid preserved platelet releasates significantly stimulated fibroblast proliferation. Twenty-one-day-old platelets were as stimulatory as 2-day-old platelets. Total protein concentration, PDGF, and transforming growth factor-beta concentrations remained constant throughout the 21-day course. Western blot analysis using an antibody against human PDGF revealed minimal protein degradation over time.

CONCLUSIONS

These data demonstrate that although the role of platelets as hemostatic agents degrades rapidly with time, platelets' ability to serve as a reservoir for growth factors remains intact for at least 3 weeks. These growth factors could be collected, stored, and used as a topical agent to promote healing of chronic and recalcitrant wounds.

Correlation between in vitro aggregation and thromboxane A2 production in fresh, liquid-preserved, and cryopreserved human platelets: effect of agonists, pH, and plasma and saline resuspension

BACKGROUND

Some of the tests used to assess the quality of fresh and preserved platelets (PLTs) include PLT number, PLT morphology, pH of the PLT medium, PLT response to hypotonic stress, and PLT aggregation to agonists. This study was performed to assess the function of fresh and preserved PLTs by their response to aggregation and their production of thromboxane A2 after in vitro stimulation with agonists.

STUDY DESIGN AND METHODS

PLTs isolated by apheresis procedures were stored at 22 degrees C for as long as 5 days and then frozen with 6 percent dimethyl sulfoxide, stored at -80 degrees C, thawed, washed, and resuspended in medium. The effects of agonists and the pH and composition of the medium on PLT aggregation and PLT production of thromboxane A2 after stimulation were measured.

RESULTS

The agonists and the pH and composition of the medium affected both the aggregation response and the production of thromboxane A2 by the fresh and preserved PLTs. PLT aggregation response to arachidonic acid (AA) and adenosine diphosphate (ADP) was significantly lower in the cryopreserved PLTs than in the fresh and preserved PLTs. After stimulation with AA and ADP, the cryopreserved PLTs produced more thromboxane than did the fresh and liquid-preserved PLTs.

CONCLUSIONS

The agonists and the pH and composition of the medium affected the response to aggregate and produce thromboxane in vitro in both the fresh and the liquid-preserved PLTs. PLT thromboxane A2 production may be a better in vitro test than PLT aggregation to assess PLT function in vivo.

Survival of baboon biotin-X-N-hydroxysuccinimide and 111In-oxine-labelled autologous fresh and lyophilized reconstituted platelets

BACKGROUND AND OBJECTIVES

In accordance with Food and Drug Administration (FDA) regulations, platelets can be stored in the liquid state at 22 degrees C for only 5 days. Platelets frozen with 6% dimethylsulphoxide (DMSO) can be stored at -80 degrees C for 2 years, and platelets frozen with 5% DMSO can be stored at -150 degrees C for 3 years. Studies are being conducted to determine the effects of lyophilization of platelets. In the present study, we assessed the survival of autologous lyophilized-reconstituted platelets in the baboon.

MATERIALS AND METHODS

We studied fresh baboon platelets and baboon platelets that had been treated with paraformaldehyde, frozen, lyophilized, thawed and reconstituted. Aliquots of these platelets were labelled with (111)In-oxine or biotin-X-N-hydroxysuccinimide (biotin-X-NHS) before autotransfusion, and measurements were made of the in vivo recovery and lifespan. We also evaluated the response of fresh and lyophilized platelets to in vitro agonists by measuring the level of platelet surface markers and heterotypic aggregates in the peripheral blood following the autotransfusions.

RESULTS

The (111)In-oxine- or biotin-X-NHS-labelled lyophilized, reconstituted platelets exhibited survival times of less than 15 min. These platelets did not respond to stimulation with agonists to decrease platelet GPIb and increase platelet P-selectin and platelet GPIIb-IIIa levels 1 min post-transfusion and they accumulated more procoagulant factor V than did the fresh platelets.

CONCLUSIONS

Lyophilized reconstituted baboon platelets labelled with (111)In-oxine or biotin-X-NHS before autotransfusion exhibited an in vivo circulation time of less than 15 min. Further study of the lyophilized, reconstituted platelets is required to evaluate their haemostatic function.

In vitro testing of fresh and lyophilized reconstituted human and baboon platelets

BACKGROUND

Studies have been performed on human fresh, liquid-preserved, and cryopreserved platelets (PLTs) to assess PLT-adhesive surface receptors, PLT membrane procoagulant activity, PLT aggregation, and thromboxane production. Lyophilization has been developed as a method to preserve PLTs. This study was performed to evaluate these measurements on human and baboon fresh and lyophilized reconstituted PLTs.

STUDY DESIGN AND METHODS

In both human and baboon fresh and lyophilized PLTs, aggregation response and PLT production of thromboxane A2 were measured after stimulation, and PLT surface markers P-selectin, glycoprotein (GP) Ib, GPIIb-IIIa, and factor (F) V were measured before and after stimulation.

RESULTS

Fresh PLTs responded to the dual agonists arachidonic acid and adenosine diphosphate (ADP) to aggregate and produce thromboxane A2, and in both the PLT surface markers P-selectin and GPIIb-IIIa increased and GPIb decreased after stimulation. Neither human nor baboon lyophilized reconstituted PLTs aggregated to dual agonists, and neither produced thromboxane A2, increased PLT surface markers P-selectin or GPIIb-IIIa, or decreased PLT GPIb after stimulation. Nevertheless, after recalcification the lyophilized reconstituted PLTs accumulated FV to a significantly greater degree than fresh PLTs.

CONCLUSIONS

Lyophilized reconstituted PLTs exhibited modification of the PLT membrane that interfered with aggregation and thromboxane production, prevented increases in PLT P-selectin and GPIIb-IIIa and decreases in GPIb after stimulation, and increased FV accumulation after recalcification. The in vitro data suggest that lyophilized PLTs may have reduced in vivo survival. In vivo studies are needed to determine the survival and function of lyophilized PLTs.

Restoration of red blood cell volume following 2-unit red blood cell apheresis

BACKGROUND AND OBJECTIVES

Blood donors who weigh at least 130 lbs (59 kg) and have a haematocrit of at least 40 V per cent can donate 2 units of blood, from which a 360-ml volume of red blood cells (RBC) can be isolated. This study was carried out in seven healthy male blood donors to assess the restoration of the RBC volume 1 month following a 2-unit RBC apheresis procedure.

MATERIALS AND METHODS

RBC volumes were measured prior to donation and 4 weeks after the 2-unit RBC apheresis procedure without oral iron supplementation.

RESULTS

Four weeks after the removal of 2 units of RBC from the male donors not supplemented with oral iron, the RBC volume was restored to 92% of the precollection value. The 360-ml volume of RBC collected represented 12-19% of the donor's original RBC volume.

CONCLUSIONS

Male donors can safely donate 2 units of RBC and will restore a mean of 92% of their RBC volume within 1 month without iron supplementation.

Circulation and distribution of autotransfused fresh, liquid-preserved and cryopreserved baboon platelets

BACKGROUND AND OBJECTIVES

Studies were carried out in five healthy male baboons to determine the 111indium oxine (111In-oxine) survival of autologous fresh, liquid-preserved and cryopreserved platelets. Simultaneous organ-distribution studies were performed to determine the percentage uptake of platelets by the spleen and/or liver.

MATERIALS AND METHODS

Each of five baboons was transfused, on three different occasions, with autologous fresh platelets stored at 22 degrees C for 18 h, liquid-preserved platelets stored at 22 degrees C for 5 days and washed previously frozen platelets, labelled with 111In-oxine.

RESULTS

In vivo recovery at 2 h was 81% for the fresh platelets, 54% for the previously frozen platelets and 44% for the 5-day-old liquid-preserved platelets. The weighted mean life span was 5.4 days for fresh platelets, 4.2 days for previously frozen platelets and 2 days for liquid preserved platelets. Increased radioactivity was detected over the liver 2 h after transfusion for both the previously frozen and liquid-preserved platelets.

CONCLUSIONS

Cryopreserved platelets and liquid-preserved platelets stored at 22 degrees C for 5 days had reduced survival 2 h post-transfusion and reduced life span values compared to fresh platelets. In addition, the finding of increased radioactivity over the liver in the baboons that received cryopreserved and liquid-preserved platelets suggested that the liver was the site for removal of the non-viable platelets.

Induction of platelet formation from megakaryocytoid cells by nitric oxide

Although the growth factors that regulate megakaryocytopoiesis are well known, the molecular determinants of platelet formation from mature megakaryocytes remain poorly understood. Morphological changes in megakaryocytes associated with platelet formation and removal of senescent megakaryocytes are suggestive of an apoptotic process. Previously, we have established that nitric oxide (NO) can induce apoptosis in megakaryocytoid cell lines. To determine whether there is an association between NO-induced apoptosis and platelet production, we exposed Meg-01 cells to S-nitrosoglutathione (GSNO) with or without thrombopoeitin (TPO) pretreatment and used flow cytometry and electron microscopy to assess platelet-sized particle formation. Meg-01 cells treated with TPO alone produced few platelet-sized particles (<3% of total counts), whereas treatment with GSNO alone produced a significant percentage of platelet-sized particles (22 +/- 4% of total counts); when combined with TPO pretreatment, however, GSNO led to a marked increase in platelet-sized particle production (48 +/- 3% of total counts). Electron microscopy confirmed that Meg-01 cells treated with TPO and GSNO yielded platelet-sized particles with morphological features specific for platelet forms. The platelet-sized particle population appears to be functional, because addition of calcium, fibrinogen, and thrombin receptor-activating peptide led to aggregation. These results demonstrate that NO facilitates platelet production, thereby establishing the essential role of NO in megakaryocyte development and thrombopoiesis.

Survival and function of baboon RBCs released from clotted blood and washed before autologous transfusion

BACKGROUND

One alternative to an allogeneic transfusion is the salvaging of the patient's own shed blood. In this study, baboon blood was allowed to clot and the RBCs that were released from the clotted blood lysed with and without urokinase were washed before autologous transfusion.

STUDY DESIGN AND METHODS

Forty-four studies were done in 13 baboons (Papio cynocephalus or Papio anubis) over a 3-year period. In 24 studies, a 50-mL volume of blood was collected without an anticoagulant and stored at 22 degrees C for as long as 72 hours before washing and autologous transfusion. In 20 other studies, a 50-mL volume of blood was collected without an anticoagulant and allowed to clot for 30 to 60 minutes. Urokinase, ranging from 2,500 to 10,000 units per mL, was added, and the blood was stored at 22 degrees C for 24 hours before washing and autologous transfusion.

RESULTS

RBCs that were stored at 22 degrees C without urokinase for 24 hours exhibited an in vitro recovery value of 45 percent, a (51)Cr 24-hour posttransfusion survival of 86 percent, and an index of therapeutic effectiveness of 39 percent. The (51)Cr T(50) value was normal at 14 days, and RBC oxygen-transport function was slightly reduced. RBCs that were stored at 22 degrees C for 24 hours with 10,000 units per mL of urokinase exhibited an in vitro recovery value of 89 percent, a (51)Cr 24-hour posttransfusion survival value of 86 percent, and an index of therapeutic effectiveness of 76 percent. The (51)Cr T(50) value was normal at 14 days, and the RBC oxygen-transport function was only slightly reduced.

CONCLUSION

Autologous baboon RBCs isolated from clotted blood treated or not treated with urokinase and washed before transfusion have excellent survival and normal or only slightly reduced oxygen-transport function.

Survival, function, and hemolysis of shed red blood cells processed as nonwashed blood and washed red blood cells

BACKGROUND

Shed nonwashed blood and shed washed red blood cells (RBC) are being used as alternatives to allogeneic liquid-preserved RBC for patients during thoracic and cardiovascular surgical procedures.

METHODS

Mongrel dogs were bled a volume of blood into the abdominal cavity and the shed blood was reinfused as nonwashed blood or washed RBC. The 51Cr RBC volumes were measured before, immediately after, and 24 hours after the exchange transfusion to assess the recovery of the shed RBC and the 24-hour posttransfusion survival. Compatible dogs were given allogeneic transfusions of 51Cr-labeled nonwashed blood and washed RBC, and 24-hour posttransfusion survival and half-life were measured.

RESULTS

Immediately after the 100% exchange transfusion, the recovery value was 62% for the nonwashed shed blood and 82% for the washed RBC. Both the nonwashed blood and the washed RBC had 24-hour posttransfusion survival values of 90% and normal oxygen transport function after the exchange transfusion. Compatible allogeneic 51Cr-labeled nonwashed blood and washed RBC had normal 24-hour posttranfusion survival and 51Cr half-life values.

CONCLUSIONS

The survival, function, and hemolysis of shed nonwashed blood and shed washed RBC were similar to fresh blood in the dog that underwent a 100% exchange transfusion.

Autologous platelet-rich plasma isolated using the Haemonetics Cell Saver 5 and Haemonetics MCS+ for the preparation of platelet gel

BACKGROUND AND OBJECTIVES

We compared three methods of isolating platelet-rich plasma (PRP) using the Haemonetics Cell Saver 5 and one method of isolating PRP by plateletpheresis using the Haemonetics MCS+. PRP contains both platelets and fibrinogen, which are used in the preparation of haemostatic agents.

MATERIALS AND METHODS

When the Haemonetics Cell Saver 5 was used, 500 ml of blood from each of 30 normal volunteer donors was collected into 70 ml of citrate-phosphate-dextrose (CPD) anticoagulant. In a further 14 normal volunteers, the Haemonetics MCS+ was used to isolate PRP by plateletpheresis using an acid citrate dextrose (ACD) to blood ratio of 1 : 9. In a separate study, CPD-anticoagulated whole blood from another 30 volunteers was used for measurement of fibrinogen levels in the plasma and cryoprecipitate.

RESULTS

A larger volume of PRP can be collected using the Haemonetics Cell Saver 5 than by using the Haemonetics MCS+. The platelet concentration and the total number of platelets were higher in the PRP isolated using the Haemonetics MCS+ than in the PRP isolated by the three methods used with the Haemonetics Cell Saver 5, with differences in platelet concentration and PRP volume among the four methods. The mean fibrinogen level in the plasma was 253 mg % +/- 47 (SD) and in the cryoprecipitate was 1085 mg % +/- 304 (SD).

CONCLUSIONS

The most appropriate method of PRP isolation for preparation of platelet gel is dependent upon the specific surgical procedure to be undertaken and the patient's needs.

Circulating monocyte-platelet aggregates are a more sensitive marker of in vivo platelet activation than platelet surface P-selectin: studies in baboons, human coronary intervention, and human acute myocardial infarction

BACKGROUND

Platelet surface P-selectin is considered the "gold standard" marker of platelet activation. Degranulated, P-selectin-positive platelets, however, aggregate with leukocytes in vitro and rapidly lose surface P-selectin in vivo.

METHODS AND RESULTS

Flow cytometric tracking of autologous, biotinylated platelets in baboons enabled us to directly demonstrate for the first time in vivo that (1) infused degranulated platelets very rapidly form circulating aggregates with monocytes and neutrophils, and (2) 30 minutes after infusion of the degranulated platelets, the percentage of circulating monocytes aggregated with infused platelets persist at high levels, whereas the percentage of circulating neutrophils aggregated with infused platelets and the platelet surface P-selectin of nonaggregated infused platelets return to baseline. We therefore performed 2 clinical studies in patients with acute coronary syndromes. First, after percutaneous coronary intervention (n=10), there was an increased number of circulating monocyte-platelet (and to a lesser extent, neutrophil-platelet) aggregates but not P-selectin-positive platelets. Second, of 93 patients presenting to an Emergency Department with chest pain, patients with acute myocardial infarction (AMI) (n=9) had more circulating monocyte-platelet aggregates (34.2+/-10.3% [mean+/-SEM]) than patients with no AMI (n=84, 19.3+/-1.4%, P<0.05) and normal control subjects (n=10, 11.5+/-0.8%, P<0.001). Circulating P-selectin-positive platelets, however, were not increased in chest pain patients with or without AMI.

CONCLUSIONS

As demonstrated by 3 independent means (in vivo tracking of activated platelets in baboons, human coronary intervention, and human AMI), circulating monocyte-platelet aggregates are a more sensitive marker of in vivo platelet activation than platelet surface P-selectin.

Subtle alternating electrocardiographic morphology as an indicator of decreased cardiac electrical stability

Observations from finite-element computer models, together with analytic developments based on percolation theory have suggested that subtle fluctuations of ECG morphology might serve as an indicator diminished cardiac electrical stability. With fixed-rate atrial pacing in canines, we have previously observed a pattern of alternation in T wave energy which correlated with cardiac electrical stability. We report here on a series of 20 canine experiments in which cardiac electrical stability (measured via Ventricular Fibrillation Threshold determination) was compared to a non-degenerate, multidimensional measurement of the degree of alternating activity present in the ECG complex morphology. The decrease in cardiac electrical stability brought on by both coronary artery occlusion and systemic hypothermia was consistently accompanied by subtle alternation in ECG morphology, with the absolute degree of alternating activity being significantly (negatively) correlated with cardiac electrical stability.

Anemia-induced increase in the bleeding time: implications for treatment of nonsurgical blood loss

BACKGROUND

Preoperative bleeding time (BT) does not correlate with postoperative bleeding in patients subjected to surgical procedures. A significant positive correlation has been reported between the BT 2 hours after cardiopulmonary bypass surgery and the nonsurgical blood loss during the first 4 hours after bypass surgery. This study was done to investigate the effect of Hct and platelet count on the BT measurement in normal, healthy men and women.

STUDY DESIGN AND METHODS

To assess the relative effect of RBCs and platelets on the BT, 22 healthy male and 7 healthy female volunteers were subjected to the removal of 2 units of RBCs (360 mL), followed by the return of the platelet-rich plasma (PRP) from both units and the infusion of 1000 mL of 0.9-percent NaCl. Four of the men and all seven women received their RBCs 1 hour after their removal. Shed blood levels of thromboxane B(2) (TXB(2)), 6-keto prostaglandin F(1 alpha), and peripheral venous Hct were measured. BTs were measured in 15 men and 13 women before and after a plateletpheresis procedure to collect 3.6 x 10(11) platelets per unit.

RESULTS

The 2-unit RBC apheresis procedure produced a 60-percent increase in the BT associated with a 15-percent reduction in the peripheral venous Hct and a 9-percent reduction in the platelet count. The plateletpheresis procedure produced a 32-percent decrease in the platelet count, no change in peripheral venous Hct, and no change in the BT. After the removal of 2 units of RBCs, the shed blood TXB(2) level decreased significantly. Reinfusion of 2 units of RBCs restored the BT and restored the TXB(2) level to the baseline levels.

CONCLUSION

The acute reduction in Hct produced a reversible platelet dysfunction manifested by an increase in BT and a decrease in the shed blood TXB(2) level at the template BT site. Return of the RBCs restored both the BT and the shed blood TXB(2) level to normal. The platelet dysfunction observed with the reduction in Hct was due in part to a reduction in shed blood TXB(2) and other, unknown mechanisms.

A multicenter study of in vitro and in vivo values in human RBCs frozen with 40-percent (wt/vol) glycerol and stored after deglycerolization for 15 days at 4 degrees C in AS-3: assessment of RBC processing in the ACP 215

BACKGROUND

The FDA has approved the storage of frozen RBCs at -80 degrees C for 10 years. After deglycerolization, the RBCs can be stored at 4 degrees C for no more than 24 hours, because open systems are currently being used. Five laboratories have been evaluating an automated, functionally closed system (ACP 215, Haemonetics) for both the glycerolization and deglycerolization processes.

STUDY DESIGN AND METHODS

Studies were performed at three military sites and two civilian sites. Each site performed in vitro testing of 20 units of RBCs. In addition, one military site and two civilian sites conducted autologous transfusion studies on ten units of previously frozen, deglycerolized RBCs that had been stored at 4 degrees C in AS-3 for 15 days. At one of the civilian sites, 10 volunteers received autologous transfusions on two occasions in a randomized manner, once with previously frozen RBCs that had been stored at 4 degrees C in AS-3 for 15 days after deglycerolization and once with liquid-preserved RBCs that had been stored at 4 degrees C in AS-1 for 42 days.

RESULTS

The mean +/- SD in vitro freeze-thaw-wash recovery value was 87 +/- 5 percent; the mean +/- SD supernatant osmolality on the day of deglycerolization was 297 +/- 5 mOsm per kg of H(2)O, and the mean +/- SD percentage of hemolysis after storage at 4 degrees C in AS-3 for 15 days was 0.60 +/- 0.2 percent. The paired data from the study of 10 persons at the civilian site showed a mean +/- SD 24-hour posttransfusion survival of 76 +/- 6 percent for RBCs that had been stored at 4 degrees C for 15 days after deglycerolization and 72 +/- 5 percent for RBCs stored at 4 degrees C in AS-1 for 42 days. At the three sites at which 24-hour posttransfusion survival values were measured by three double-label procedures, a mean +/- SD 24-hour posttransfusion survival of 77 +/- 9 percent was observed for 36 autologous transfusions to 12 females and 24 males of previously frozen RBCs that had been stored at 4 degrees C in AS-3 for 15 days after deglycerolization.

CONCLUSION

The multicenter study showed the acceptable quality of RBCs that were glycerolized and deglycerolized in the automated ACP 215 instrument and stored in AS-3 at 4 degrees C for 15 days.

In vivo survival of apheresis RBCs, frozen with 40-percent (wt/vol) glycerol, deglycerolized in the ACP 215, and stored at 4 degrees C in AS-3 for up to 21 days

BACKGROUND

The FDA has approved the storage of frozen RBCs at -80 degrees C for 10 years and the postwash storage at 4 degrees C for no more than 24 hours. The 4 degrees C postwash storage period is limited to 24 hours, because the current deglycerolization systems are functionally open systems.

STUDY DESIGN AND METHODS

Two units of RBCs were collected from each of 13 healthy male volunteers. The RBCs were collected in CP2D by the FDA-approved protocol for an automated apheresis device (MCS, LN8150, Haemonetics) and were stored at 4 degrees C in AS-3 for 6 days. Using a single disposable glycerolization set in an automated, functionally closed system (ACP 215, Haemonetics) each unit was transferred to a 1000-mL PVC plastic bag and glycerolized to a concentration of 40-percent (wt/vol) glycerol and frozen at -80 degrees C. A single disposable deglycerolization set in the ACP 215 was used to deglycerolize the 2 units from the same donor. The deglycerolized RBCs were stored at 4 degrees C in AS-3 for as long as 21 days.

RESULTS

The mean +/- SD freeze-thaw-wash recovery value was 89.4 +/- 3 percent. The residual hemolysis in the RBCs stored at 4 degrees C in AS-3 for 21 days after deglycerolization was 0.9 +/- 0.2 percent, and the units were negative for both aerobic and anaerobic bacteria. The mean Nageotte WBC count was 9 x 10(6) per unit. When the deglycerolized RBCs were given as an autologous transfusion after storage at 4 degrees C in AS-3 for the 7- to 18-day period, the mean +/- SD 24-hour posttransfusion survival was 77 +/- 7 percent, and the index of therapeutic effectiveness was 69 +/- 8 percent.

CONCLUSION

Two units of human RBCs collected from a single donor by apheresis in the MCS using an LN8150 set can be glycerolized sequentially with a single disposable set and deglycerolized sequentially with another single disposable set in the ACP 215. The previously frozen RBCs stored in AS-3 for 7 to 18 days at 4 degrees C had acceptable hemolysis and an acceptable mean 24-hour posttransfusion survival value and index of therapeutic effectiveness.

In vitro and in vivo measurements of gamma-radiated, frozen, glycerolized RBCs

BACKGROUND

Transfusion-associated GVHD results from the presence of viable lymphocytes in transfused allogeneic blood components. Viable immunocompetent lymphocytes have been detected in RBCs that were frozen with glycerol and washed before transfusion.

STUDY DESIGN AND METHODS

The study reported here assessed the effect of irradiation on human RBCs frozen with 40-percent (wt/vol) glycerol and stored at -80 degrees C. In vitro and in vivo testing was done on human RBCs that were frozen with 40-percent (wt/vol) glycerol at -80 degrees C, with some units exposed to 2500 cGy of gamma radiation and others not irradiated, and that, after thawing and washing, were stored in a sodium chloride-glucose solution at 4 degrees C for 3 days before autologous transfusion.

RESULTS

The glycerol-frozen RBCs treated with 2500 cGy before deglycerolization had a mean freeze-thaw-wash recovery of 87 percent and a mean 24-hour posttransfusion survival of 86 percent after storage for 3 days at 4 degrees C in a 0.9-percent NaCl and 0.2-percent glucose solution. For the nonirradiated units, the mean freeze-thaw-wash recovery was 85 percent and the mean 24-hour posttransfusion survival was 83 percent.

CONCLUSION

These data show similar, acceptable results for RBCs frozen with 40-percent (wt/vol) glycerol at -80 degrees C and treated in the frozen state with 2500 cGy of gamma radiation and for RBCs that were not irradiated, all of which were washed and then stored in a sodium chloride-glucose solution for 3 days before autologous transfusion.

An experiment with glycerol-frozen red blood cells stored at -80 degrees C for up to 37 years

BACKGROUND AND OBJECTIVES

Red cells frozen using 40% W/V glycerol are currently FDA approved for frozen storage at -80 degrees C for up to 10 years.

MATERIALS AND METHODS

Red cells frozen with 40% W/V glycerol and stored at -80 degrees C for up to 37 years were thawed, deglycerolized, and stored at 4 degrees C for 24 h.

RESULTS

Red cells frozen for up to 37 years had mean freeze-thaw-wash recovery values of 75%, less than 1% hemolysis, and normal ATP, 2,3-DPG and P50 levels, and 60% of normal RBC K(+) levels.

CONCLUSIONS

Red cells frozen with 40% W/V glycerol can be stored at -80 degrees C for up to 37 years with acceptable in vitro results.

In vitro and in vivo measurements of human RBCs frozen with glycerol and subjected to various storage temperatures before deglycerolization and storage at 4 degrees C for 3 days

BACKGROUND

This study was designed to assess the effects of changes in storage temperature of frozen RBCs such as might occur during a malfunction of the -80 degrees C mechanical freezer or during shipment.

STUDY DESIGN AND METHODS

Fifteen participants donated blood for autologous transfusion of RBCs; all RBCs were frozen with 40-percent (wt/vol) glycerol. Five subjects received RBCs that were stored at -80 degrees C alone before transfusion. Five subjects received RBCs that were stored initially at -80 degrees C, then at -40 degrees C for 4 weeks, and finally at -80 degrees C before transfusion. Five subjects received RBCs that were stored at -80 degrees C, then at -20 degrees C for 2 weeks, and finally at -80 degrees C before transfusion. After deglycerolization, the RBCs were stored at 4 degrees C in a sodium chloride-glucose solution for 3 days before transfusion.

RESULTS

No significant differences were observed in freeze-thaw recovery, freeze-thaw-wash recovery, 24-hour posttransfusion survival, index of therapeutic effectiveness, or RBC ATP levels. Greater hemolysis and reduced RBC K+ levels were observed in the units stored at -80 degrees C/-40 degrees C/-80 degrees C and in those stored at -80 degrees C/ -20 degrees C/-80 degrees C compared with the units stored at -80 degrees C alone, but these differences did not affect the 24-hour posttransfusion survival.

CONCLUSIONS

The results of this study indicated that RBCs frozen with 40-percent (wt/vol) glycerol can be stored at -40 degrees C for 4 weeks or at -20 degrees C for 2 weeks between periods of frozen storage at -80 degrees C with satisfactory results.

24-hour 51Cr post-transfusion survival, 51Cr life span and haemolysis of red blood cells stored at 4 degrees C for 56 days in AS-3

BACKGROUND AND OBJECTIVES

Red blood cells (RBC) were collected either by a manual method using a 16-gauge needle or by an apheresis procedure using an 18-gauge needle, and were stored at 4 degrees C in a solution of CP2D (anticoagulant)/AS-3 (Nutricel) for 56 days. The purpose was to compare the outcome of the autotransfused red cells collected by both techniques.

MATERIALS AND METHODS

Five healthy male volunteers were studied on two occasions.

RESULTS

The autotransfusions of the manual and apheresed RBC resulted in a mean 24-h post-transfusion survival of 71%, a normal mean 51Cr RBC life span, a 2,3 DPG level that was less than 10% of normal, and 0.6% haemolysis.

CONCLUSIONS

Whether collected manually or by apheresis, the outcomes were similar for RBC stored at 4 degrees C for 56 days in CP2D/AS-3.

The survival, function, and hemolysis of human RBCs stored at 4 degrees C in additive solution (AS-1, AS-3, or AS-5) for 42 days and then biochemically modified, frozen, thawed, washed, and stored at 4 degrees C in sodium chloride and glucose solution for 24 hours

BACKGROUND

A study was done to assess the quality of RBCs stored at 4 degrees C in AS-1, AS-3, or AS-5 for 42 days before biochemical modification and freezing.

STUDY DESIGN AND METHODS

RBCs were stored at 4 degrees C for 42 days in AS-1, AS-3, or AS-5 and then biochemically modified with pyruvate, inosine, phosphate, and adenine solution (Rejuvesol), frozen with 40-percent (wt/vol) glycerol, and stored at -80 degrees C for at least 2 months. The RBCs were deglycerolized by the use of a cell washer (Haemonetics 115), and stored for 24 hours at 4 degrees C in a 0.9-percent sodium chloride and 0.2-percent glucose solution before the autologous transfusion.

RESULTS

The mean freeze-thaw-wash recovery process produced RBC recovery values of 85 percent, with the mean 24-hour posttransfusion survival at 75 percent, and the mean index of therapeutic effectiveness at 64 percent for the RBCs stored at 4 degrees C in AS-1, AS-3, or AS-5 for 42 days before biochemical modification and freezing. All the units exhibited normal or slightly higher than normal 2,3 DPG levels after deglycerolization and postwash storage at 4 degrees C for 24 hours.

CONCLUSION

RBCs stored in AS-1, AS-3, or AS-5 at 4 degrees C for 42 days and then biochemically modified with pyruvate, inosine, phosphate, and adenine and glycerolized, frozen, washed, and stored at 4 degrees C for 24 hours before autologous transfusion had acceptable in vitro and in vivo measurements.

Intravascular circulation and distribution of human 51Cr-DBBF stroma-free hemoglobin, 51Cr-plasma, 51Cr-saline, 59FE-plasma, and 125I-albumin in the mouse

Male B6C3HF1 mice were infused with human 51Cr-labeled DBBF (bis 3,5-dibromosalicyl fumarate) crosslinked stroma-free hemoglobin (SFH). In the first hour following SFH infusion, 11.2% of the infused radioactivity was found in the skin, 11.4% in muscle, 9.1% in the skeleton, and 5% in the liver. Twenty-four hours after infusion, 15.4% of the radioactivity was found in the skin, 10.3%, in the muscle, 16.6% in the skeleton, and 6.7% in the liver. The circulation and distribution of 51Cr-labeled DBBF-SFH were compared with levels of 51Cr labeled plasma, 51Cr in saline, 59Fe labeled plasma, and 125I albumin. The radioactivity in the blood was similar for 51Cr-DBBF-SFH, 51Cr-plasma, and 59Fe-plasma. During the 24-hour post-infusion period, extravascular distribution of the 51Cr-saline, 51Cr-plasma, and 125I albumin within the organs was similar to that of 51Cr-DBBF-SFH, with the highest levels being in skin, muscle, skeleton and liver, and no increase in the levels in the lung or spleen. The distribution of 59Fe compared to that of 51Cr-DBBF, 51Cr-plasma, 51Cr-saline, and 125I albumin can be explained by the fact that 59Fe is utilized in the production of new red blood cells.

Posttransfusion survival (24-hour) and hemolysis of previously frozen, deglycerolized RBCs after storage at 4 degrees C for up to 14 days in sodium chloride alone or sodium chloride supplemented with additive solutions

BACKGROUND

Previously frozen human RBCs currently are glycerolized and deglycerolized by the use of open systems that limit storage of the deglycerolized RBCs at 4 degrees C to only 24 hours.

STUDY DESIGN AND METHODS

Healthy male volunteers who met AABB requirements for blood donors (n = 38) were studied. A volume of 450 mL of blood was collected into CPDA-1. The RBC concentrates were stored at 4 degrees C for 3 to 6 days before being frozen with 40-percent (wt/vol) glycerol and stored at -80 degrees C. The RBCs were deglycerolized, resuspended in 0.9-percent sodium chloride and 0.2-percent glucose (SG) solution or SG solution supplemented with AS-1, AS-3, or AS-5, and stored in the resuspension medium at 4 degrees C for 14 days.

RESULTS

The mean +/- SD freeze-thaw-wash process recovery was 90.0 +/- 4.0 percent for all 38 units. The mean 24-hour posttransfusion survival value was 79 percent for deglycerolized RBC stored at 4 degrees C for 7 days in SG alone, SG plus AS-3, or SG plus AS-5. Deglycerolized RBC that were stored at 4 C for 14 days in SG supplemented with AS-1, AS-3, or AS-5 had a mean 24-hour posttransfusion survival of 74 percent. After 7 days of storage of deglycerolized RBCs in SG alone, the mean hemolysis was 3. 7 percent. After 14 days of storage of deglycerolized RBCs in SG supplemented with AS-1, AS-3, or AS-5, the mean hemolysis was 2.5 percent.

CONCLUSIONS

The levels of hemolysis did not correlate with the 24-hour posttransfusion survival values.

Photochemical decontamination of red blood cell concentrates with the silicon phthalocyanine PC 4 and red light

Various approaches are being developed for virus inactivation of red blood cell concentrates (RBCC) in order to increase the safety of the blood supply. We have been studying the silicon phthalocyanine Pc 4 for this purpose, a photosensitizer activated with red light. Pc 4 targets the envelope of pathogenic viruses such as HIV. To protect RBC during the process two main approaches are used: (i) inclusion of quenchers of reactive oxygen species produced during the treatment. Tocopherol succinate was found to be most effective for this purpose; (ii) formulation of Pc 4, a lipophilic compound, in liposomes that reduce its binding to RBC but not to viruses. As a light source we used a light emitting diode array emitting at 670-680 nm. An efficient mixing device ensures homogenous light exposure during treatment of intact RBCC. Treatment of 50 ml RBCC with 5 microM Pc 4 and 18 J/cm(2) light results in the inactivation of > or = 5.5 log(10) HIV, > or = 6.3 log(10), VSV and > or = 5 log(10) of PRV and BVDV. The relative sensitivities of these viruses based on the slope of virus kill versus light dose are 1.0, 1.25, 1.5 and 1.9 for HIV, VSV, PRV and BVDV, respectively. To achieve the same level of virus inactivation in 350 ml RBCC, the light dose needed is 40 J/cm(2). HIV actively replicating in CEM cells is as sensitive as cell-free and HIV in latently infected cells is 3-4 times more sensitive. Parasites that can be transmitted by blood transfusion (P. falciparum and T. cruzi) are even more sensitive than viruses. Following treatment, RBCC can be stored for 28 days at 4 degrees C with haemolysis below 1%. Previous studies under less favourable conditions showed that baboon RBC circulated with an acceptable 24 hr recovery and half-life. Genetic toxicological studies of Pc 4 with or without light exposure (mutagenicity in bacteria, mammalian cells in vitro and clastogenicity in vivo) were negative. We conclude that a process using Pc 4 and red light can potentially reduce the risk of transmitting pathogens in RBCC.

Effects of hemoglobin-based oxygen-carrying solutions in anesthetized rats with acute ischemic renal failure

The effects of three hemoglobin solutions were compared with those of iso-oncotic human serum albumin in rats with ischemic renal failure and sham-operated controls. Unmodified and alpha-alpha cross-linked hemoglobins both increase mean arterial pressure and systemic vascular resistance and reduce cardiac output substantially and to a comparable extent. In contrast, omicron-raffinose cross-linked hemoglobin has no deleterious effect on any of these parameters. In sham-operated rats unmodified hemoglobin reduces the glomerular filtration rate (GFR) by approximately 30%, whereas neither of the two cross-linked hemoglobins has any adverse effect on GFR in this group. None of the three hemoglobin solutions exacerbated the degree to which GFR was reduced by ischemia-reperfusion injury. Also, the degree of tubular necrosis induced by ischemia-reperfusion injury was also comparable in all groups. We conclude the following: (1) omicron-raffinose cross-linking, but not alpha-alpha cross-linking, ameliorates the effects of unmodified hemoglobin on vascular resistance and cardiac output; (2) both forms of cross-linking reduce the nephrotoxicity exhibited by unmodified hemoglobin in sham-operated rats; and (3) none of the hemoglobin solutions exacerbate renal injury induced by ischemia-reperfusion.

Fresh, liquid-preserved, and cryopreserved platelets: adhesive surface receptors and membrane procoagulant activity

BACKGROUND

A study in humans showed that the transfusion of previously frozen human platelets after cardiopulmonary bypass, despite decreased survival, resulted in better hemostatic function than that of liquid-preserved platelets stored at 22 degrees C for 3 to 4 days.

STUDY DESIGN AND METHODS

In this study, fresh, 3- to 4-day-old liquid-preserved, and cryopreserved human platelets were studied by the use of monoclonal antibodies directed against p-selectin, glycoprotein (GP)Ib, activated GPIIb/IIIa, and coagulation factor V in a three-color flow cytometric method.

RESULTS

The fresh and liquid-preserved platelets had normal surface levels of GPIb, while the cryopreserved platelets were composed of distinct subpopulations of GPIb-normal and GPIb-reduced platelets. On the basis of the binding of factor V, both subpopulations of cryopreserved platelets exhibited greater surface binding of factor V than did fresh and liquid-preserved platelets. Activated GPIIb/IIIa was elevated on GPIb-normal platelets, but not on GPIb-reduced platelets. Baboon platelets frozen by a procedure identical to that used to freeze human platelets also had GPIb-normal and GPIb-reduced subpopulations after the freezing-thawing-washing procedure. Autologous cryopreserved baboon platelets labeled with biotin-X-N-hydroxysuccinimide showed a rapid removal of GPIb-reduced platelets during the 5-minute postinfusion period, whereas GPIb-normal platelets had an in vivo recovery of 48 percent and a lifespan of slightly less than 6 days.

CONCLUSIONS

Improved in vivo function of cryopreserved platelets may be related to the rapid hemostatic effect of the GPIb-reduced subpopulation secondary to increased binding of factor V and expression of p-selectin.

Platelet surface p-selectin, platelet-granulocyte heterotypic aggregates, and plasma-soluble p-selectin during plateletpheresis

BACKGROUND

Plateletpheresis components have been shown to contain p-selectin-positive platelets after collection and storage. P-selectin mediates binding of activated platelets to granulocytes and monocytes. This study was undertaken to assess platelet activation, granulocyte activation, platelet-granulocyte heterotypic aggregate formation, and the plasma-soluble p-selectin level during plateletpheresis performed on a particular instrument (MCS+, Haemonetics).

STUDY DESIGN AND METHODS

Flow cytometry was used to assay platelet surface p-selectin, granulocyte iC3b receptor, and platelet-granulocyte aggregates in the platelet component, residual blood in the disposable polycarbonate bowl of the MCS+, and in the donor blood with and without the addition of in vitro agonists before, during, and after plateletpheresis. The plasma-soluble p-selectin levels in the platelet component, disposable bowl, and donor venous blood were measured by an enzyme-linked immunosorbent assay.

RESULTS

Levels of p-selectin-positive platelets, activated granulocytes, and platelet-granulocyte aggregates were greater in the disposable bowl than in the preapheresis donor blood. Levels of p-selectin-positive platelets, activated granulocytes, and platelet-granulocyte aggregates in the postapheresis donor blood were similar to those in the preapheresis donor blood. The platelet components contained no activated granulocytes or detectable platelet-granulocyte heterotypic aggregates, and only about 10-percent activated platelets. The plasma-soluble p-selectin level in the platelet component was significantly greater than that in the preapheresis donor blood, the residual blood in the disposable bowl, or the postapheresis donor blood.

CONCLUSIONS

Measurements of platelet surface p-selectin, platelet-granulocyte heterotypic aggregates, and plasma-soluble p-selectin can be used to detect platelet activation during plateletpheresis.

Effect of 24-hour whole-blood storage on plasma clotting factors

BACKGROUND

The current requirements for the preparation of fresh-frozen plasma within 8 hours of whole-blood collection were designed to maintain clotting factor activities. These requirements, however, limit the production of fresh-frozen plasma in a large blood center. There are few data on the effect of the extension of CPD whole-blood storage to 24 hours on clotting factor activity.

STUDY DESIGN AND METHODS

A 500-mL unit of whole blood was collected from 10 volunteer donors. At 1 hour after collection, a plasma sample was separated by centrifugation, and each unit was equally divided into 2 half-units, with 1 half-unit stored at 4 degrees C (range, 1-6 degrees C) and 1 half-unit stored at 22 degrees C (range, 20-24 degrees C) for 8 hours after collection. Each half-unit was then placed at 4 degrees C for further storage for 16 hours. At 8 and 24 hours after collection, plasma samples were separated from each half-unit. All plasma samples were frozen at -18 degrees C. Factors V, VII, VIII, and X; fibrinogen; antithrombin III; protein C; and protein S were measured.

RESULTS

No significant changes were noted in factors V, VII, and X; fibrinogen; antithrombin III; protein C; and protein S over the 24-hour storage period. Factor VIII in both half-units was significantly reduced, by 13 percent, from the baseline sample as compared to the level in the 8-hour storage sample (p<0.05). Factor VIII was further reduced by 15 to 20 percent after the 24-hour storage period (p<0.05).

CONCLUSION

The coagulation factor activity for all factors measured, with the exception of factor VIII, showed no significant change over the 24-hour storage period. Factor VIII was significantly decreased by 13 percent in 8-hour storage and by an additional 15 to 20 percent in 24-hour storage. For clinical situations not requiring the replacement of factor VIII only, 24-hour frozen plasma has properties comparable to those of fresh-frozen plasma.

O-raffinose cross-linking markedly reduces systemic and renal vasoconstrictor effects of unmodified human hemoglobin

The hemodynamic effects of a 20% exchange-transfusion with different solutions of highly purified human hemoglobin A-zero (A0) were evaluated. We compared unmodified hemoglobin with hemoglobin cross-linked with O-raffinose. Unmodified hemoglobin increased systemic vascular resistance and mean arterial pressure more than the O-raffinose cross-linked hemoglobin solution (by approximately 45% and approximately 14%, respectively). Unmodified hemoglobin markedly reduced cardiac output (CO) by approximately 21%, whereas CO was unaffected by the O-raffinose cross-linked hemoglobin solution. Unmodified and O-raffinose cross-linked hemoglobin solutions increased mean arterial pressure to comparable extents ( approximately 14% and approximately 9%, respectively). Unmodified hemoglobin increased renal vascular resistance 2-fold and reduced the glomerular filtration rate by 58%. In marked contrast, the O-raffinose cross-linked hemoglobin had no deleterious effect on the glomerular filtration rate, renal blood flow, or renal vascular resistance. The extents to which unmodified and O-raffinose cross-linked hemoglobin solutions inactivated nitric oxide also were compared using three separate in vitro assays: platelet nitric oxide release, nitric oxide-stimulated platelet cGMP production, and endothelium-derived relaxing factor-mediated inhibition of platelet aggregation. Unmodified hemoglobin inactivated or oxidized nitric oxide to a greater extent than the O-raffinose cross-linked hemoglobin solutions in all three assays. In summary, O-raffinose cross-linking substantially reduced the systemic vasoconstriction and the decrease in CO induced by unmodified hemoglobin and eliminated the deleterious effects of unmodified hemoglobin on renal hemodynamics and function. We hypothesize that O-raffinose cross-linking reduces the degree of oxidation of nitric oxide and that this contributes to the reduced vasoactivity of this modified hemoglobin.

Comparison of the effects of transfusions of cryopreserved and liquid-preserved platelets on hemostasis and blood loss after cardiopulmonary bypass

OBJECTIVE

The aim of the study was to compare the clinical effects and hemostatic efficiency of transfusions of platelets preserved in the frozen state for as long as 2 years with transfusions of platelets preserved in the conventional manner for as long as 5 days in patients undergoing cardiopulmonary bypass.

METHODS

Seventy-three patients were prospectively randomly assigned to receive transfusions of cryopreserved or liquid-preserved platelets. Nonsurgical blood loss was measured during and after the operation. Bleeding time, hematologic variables, and the bleeding time site shed blood were assayed before cardiopulmonary bypass and at 30 minutes and 2, 4, and 24 hours after transfusion. In vitro platelet function tests were conducted on platelets obtained from healthy volunteers.

RESULTS

No adverse sequelae of the transfusions were observed. Blood loss and the need for postoperative blood product transfusions were lower in the group receiving cryopreserved platelets. Lower posttransfusion platelet increments and a tendency toward decreased platelet survival were observed in patients receiving cryopreserved platelets. Hematocrit and plasma fibrinogen were significantly higher in this group, and the duration of intubation was shorter. In vitro, cryopreserved platelets demonstrated less aggregation, lower pH, and decreased response to hypotonic stress but generated more procoagulant activity and thromboxane.

CONCLUSIONS

(1) Cryopreserved platelet transfusions are superior to liquid-preserved platelets in reducing blood loss and the need for blood product transfusions after cardiopulmonary bypass. (2) The reduction in blood loss in the patients receiving cryopreserved platelet transfusions after cardiopulmonary bypass probably reflects improved in vivo hemostatic function of cryopreserved platelets. (3) Some in vitro measures of platelet quality (aggregation, pH, hypotonic stress) may not reflect in vivo quality of platelet transfusions after cardiopulmonary bypass, whereas other in vitro measures (platelet procoagulant activity and thromboxane) do.

The effects of aspirin and hypothermia on platelet function in vivo

Patients undergoing hypothermic cardiopulmonary bypass are often receiving aspirin therapy. Hypothermia, aspirin and cardiopulmonary bypass can each induce a platelet function defect, but it is not known if the effects of aspirin and hypothermia are additive in this regard. To address this question in humans in vivo, the forearm skin temperature of healthy volunteers was equilibrated and maintained at either normothermia (32 degrees C) or hypothermia (28 degrees C or 22 degrees C) before and 16 h after the ingestion of 650 mg aspirin. A standardized template bleeding time was performed on the forearm and the shed blood emerging from the wound was assayed for platelet surface P-selectin expression by whole blood flow cytometry (reflecting alpha granule secretion) and thromboxane B2 (the stable metabolite of thromboxane A2) by radioimmunoassay. Hypothermia resulted in marked prolongation of the bleeding time. Aspirin resulted in prolongation of the bleeding time under normothermic conditions, but only minimally augmented the hypothermia-induced prolongation of the bleeding time. Platelet surface P-selectin up-regulation in shed blood was abolished by hypothermia. Aspirin had no effect on maximal platelet surface P-selectin expression under normothermic or hypothermic conditions. Both hypothermia and aspirin resulted in markedly reduced shed blood thromboxane B2. Although aspirin slightly augmented the hypothermia-induced reduction in shed blood thromboxane B2, the concentration of thromboxane generated in shed blood under hypothermic conditions in the absence of aspirin had no effect on platelet surface P-selectin or platelet aggregation in whole blood. In conclusion, as determined by three independent parameters of the shed blood emerging from a standardized bleeding time wound (bleeding time, platelet surface P-selectin, and thromboxane B2), aspirin did not significantly augment hypothermia-induced platelet dysfunction in vivo.

Does erythrocyte infusion improve 3.2-km run performance at high altitude?

The effects of autologous erythrocyte infusion on improving exercise performance at high altitude have not previously been studied. The effects of erythrocyte infusion on 3.2-km (2-mile) run performance were evaluated during 3 days (HA3) and 14 days (HA14) exposure to high altitude (4300 m) in erythrocyte-infused (ER) and control (CON) subjects that were initially matched (P>0.05; n = 8 in each group) for age, body size and aerobic fitness. After sea-level runs (SL; 50 m), unacclimated-male subjects received either 700 ml of saline and autologous erythrocytes (42% hematocrit; ER) or saline alone (CON). The 3.2-km run times (min:s) did not differ (P>0.05) between groups at SL [mean (SEM) ER, 13:14 (00:19); CON, 13:39 (00:32)] or during HA3 [ER, 19:02 (00:18); CON, 19:44 (00:43)] and HA14 [ER, 17:44 (00:27); CON, 18:45 (00:55)] but times were slower (P<0.05) when comparing HA3 or HA14 to SL. Heart rates (HR) did not differ between groups at SL [ER, 188 (3) beats x min(-1); CON, 191 (3) beats x min(-1)], or during HA3 [ER, 170 (4) beats x min(-1); CON, 178 (4) beats x min(-1)] and HA14 [ER, 162 (6) beats x min(-1); CON, 169 (5) beats x min(-1)], but HR were lower (P<0.05) when comparing HA3 or HA14 to SL. Ratings of perceived exertion (local, central, and overall ratings) did not differ between groups at SL, HA3 or HA14, but local ratings were higher (P<0.05) at HA3 and HA14 compared to SL, and overall ratings were higher for HA3 than SL. Analysis of covariance (adjusted for SL group run times) revealed (min:s) 00:14 (HA3) and 00:28 (HA14) mean improvement tendencies (P>0.05) for ER compared to CON. Thus, no significant improvements in 3.2-km run performance were associated with erythrocyte infusion, although the ER group showed a tendency to run slightly faster at high altitude.

Porphyrin loading of lipofuscin granules in inflamed striated muscle

To further the understanding of oxidative effects on inflammation injury to muscle fiber structure, fluorescent imaging analysis of human striated muscle tissues from a variety of inflammatory or postinflammatory etiologies was undertaken in a search for accumulated coproporphyrin, a red autofluorescent byproduct of heme biosynthesis that would theoretically be formed under oxidative insult. Using a differential excitation method of in situ analysis, porphyrin autofluorescence was detected in intact fibers within the context of the yellow autofluorescent subsarcolemmal lipofuscin granules. Relative measurements of porphyrin concentration in the granules from different patients indicated that the acute/subacute inflammatory specimens grouped significantly higher than the more chronic inflammatory and nonpathological specimens. Myoglobin was also found to be associated with the granules. Myoglobin heme iron could potentially serve as a Fenton reagent for the intracellular generation of hydroxyl radicals, which are responsible for the oxidation of the porphyrinogens. High-performance liquid chromatography analysis of extracted dense particles revealed coproporphyrin as the sole porphyrin present. The observation of coproporphyrin within lipofuscin granules, previously unreported, suggests that lipofuscin accumulation in striated muscle may begin under conditions of acute oxidative stress, as marked by the oxidation of extramitochondrial porphyrinogens that are immediately incorporated into the granules.

The red cell transfusion trigger: has a sin of commission now become a sin of omission?

The benefits of a Hct range of 30 to 35 percent include improved oxygen delivery and enhanced hemostasis, which help minimize complications in patients at high risk for ischemia and perioperative nonsurgical bleeding. In these settings, the conservative transfusion practice of using a lower Hct range should be replaced with a more aggressive approach. The known risks of blood transfusion would appear to be sufficiently low and the benefits sufficiently high to justify maintaining a Hct of at least 30 percent. An even higher Hct, of 35 percent, may be desirable in patients who have overt cardiopulmonary disease or who are at high risk for myocardial ischemia. Many retrospective studies have been conducted to persuade us that a conservative transfusion trigger is a safe and prudent practice, but retrospective studies are not what we need. What we need is a series of well-designed, prospective, randomized trials to evaluate the impact of a more aggressive transfusion policy on perioperative mortality, morbidity, and nonsurgical bleeding in patients with known cardiopulmonary disease or who are at high risk for myocardial and cerebrovascular ischemia.

Patients with venous stasis ulceration have increased monocyte-platelet aggregation

PURPOSE

Leukocyte activation has been implicated in the pathogenesis of venous stasis ulceration, but the involvement of activated platelets and leukocyte-platelet aggregates has not been previously investigated. The purpose of this study was to determine whether patients with venous stasis ulceration have increased platelet activation and a propensity toward formation of leukocyte-platelet aggregates.

METHODS

Blood was drawn from the superficial veins of the leg just proximal to a venous stasis ulcer and from an antecubital vein in 14 patients with venous stasis ulceration. Blood was also drawn from the antecubital vein of 14 volunteers without evidence of venous disease. Whole-blood flow cytometry was used to analyze the samples before and after activation with a panel of agonists for evidence of platelet activation and the formation of leukocyte-platelet aggregates.

RESULTS

Patients with venous stasis ulceration had a greater number of monocyte-platelet aggregates in both the arm and leg samples than did the control subjects (p < 0.01). Furthermore, antecubital blood samples from patients with venous stasis ulceration stimulated with either thrombin-receptor agonist peptide, adenosine diphosphate, or phorbol myristate acetate formed more monocyte-platelet aggregates than did control samples (p < 0.05). No differences in platelet activation or neutrophil-platelet aggregate formation were noted among the three sample groups.

CONCLUSIONS

Patients with venous stasis ulceration have an increase in the number of monocyte-platelet aggregates in systemic venous blood as well as in venous blood adjacent to a venous stasis ulcer, implicating the monocyte as the leukocyte involved in the pathogenesis of venous stasis ulceration. No association was identified between the presence of a venous stasis ulcer and either neutrophil-platelet aggregation or the activation of individual platelets. Because platelet activation is necessary for the formation of monocyte-platelet aggregates, these data also suggest that monocyte-platelet aggregation is a more sensitive marker for in vivo platelet activation than is the identification of individual activated platelets.

Thermal and cardiovascular strain from hypohydration: influence of exercise intensity

This study determined the effects of exercise intensity on the physiologic (thermal and cardiovascular) strain induced from hypohydration during heat stress. We hypothesized that the added thermal and cardiovascular strain induced by hypohydration would be greater during high intensity than low intensity exercise. Nine heat-acclimated men completed a matrix of nine trials: three exercise intensities, 25%, 45% and 65% VO2 max; and three hydration levels, euhydration and hypohydration at 3% and 5% body weight loss (BWL). During each trial, subjects attempted 50 min of treadmill exercise in a hot room (30 degrees C db, 50% rh) while body temperatures and cardiac output were measured. Hypohydration was achieved by exercise and fluid restriction the day preceding the trials. Core temperature increased (P<0.05) 0.12 degrees C per%BWL at each hypohydration level and was not affected by exercise intensity. Cardiac output was reduced (P<0.05) compared to euhydration levels and was reduced more during high compared to low intensity exercise after 5% BWL. It was concluded that: a) the thermal penalty (core temperature increase) accompanying hypohydration is not altered by exercise intensity; and b) at severe hypohydration levels, the cardiovascular penalty (cardiac output reduction) increases with exercise intensity.

Increased platelet reactivity and circulating monocyte-platelet aggregates in patients with stable coronary artery disease

OBJECTIVES

We sought to examine whether patients with stable coronary artery disease (CAD) have increased platelet reactivity and an enhanced propensity to form monocyte-platelet aggregates.

BACKGROUND

Platelet-dependent thrombosis and leukocyte infiltration into the vessel wall are characteristic cellular events seen in atherosclerosis.

METHODS

Anticoagulated peripheral venous blood from 19 patients with stable CAD and 19 normal control subjects was incubated with or without various platelet agonists and analyzed by whole blood flow cytometry.

RESULTS

Circulating degranulated platelets were increased in patients with CAD compared with control subjects (mean [+/- SEM] percent P-selectin-positive platelets: 2.1 +/- 0.2 vs. 1.5 +/- 0.2, p < 0.01) and were more reactive to stimulation with 1 micromol/liter of adenosine diphosphate (ADP) (28.7 +/- 3.9 vs. 16.1 +/- 2.2, p < 0.01), 1 micromol/liter of ADP/epinephrine (51.4 +/- 4.6 vs. 37.5 +/- 3.8, p < 0.05) or 5 micromol/liter of thrombin receptor agonist peptide (TRAP) (65.7 +/- 6.8 vs. 20.2 +/- 5.1, p < 0.01). Patients with stable CAD also had increased circulating monocyte-platelet aggregates compared with control subjects (percent platelet-positive monocytes: 15.3 +/- 3.0 vs. 6.3 +/- 0.9, p < 0.01). Furthermore, patients with stable CAD formed more monocyte-platelet aggregates than did control subjects when their whole blood was stimulated with 1 micromol/liter of ADP (50.4 +/- 4.5 vs. 28.1 +/- 5.3, p < 0.01), 1 micromol/liter of ADP/epinephrine (60.7 +/- 4.3 vs. 48.0 +/- 4.8, p < 0.05) or 5 micromol/liter of TRAP (67.6 +/- 5.7 vs. 34.3 +/- 7.0, p < 0.01).

CONCLUSIONS

Patients with stable CAD have circulating activated platelets, circulating monocyte-platelet aggregates, increased platelet reactivity and an increased propensity to form monocyte-platelet aggregates.

The volume of blood shed during the bleeding time correlates with the peripheral venous hematocrit

The relation among the bleeding time, the peripheral venous hematocrit, and the amount of blood shed at the template bleeding time site has not been previously defined. We studied this relation in 227 persons: 26 were patients with idiopathic thrombocytopenic purpura (ITP), 137 were patients with a variety of other bleeding disorders, and 64 were healthy subjects. The bleeding time (mean +/- SD) for the healthy group was 7.1 +/- 1.2 minutes, and the amount of shed blood was 136.4 +/- 47.2 microL; in patients with ITP the bleeding time was 14.0 +/- 4.1 minutes and the shed blood was 508.1 +/- 387 microL; and in the group with other bleeding disorders, the mean bleeding time was 9.0 +/- 3.5 minutes, and the amount of shed blood was 224.7 +/- 184 microL. Bleeding times for all persons studied showed a significant correlation of 0.75 for the amount of shed blood on the filter paper and a significant correlation of 0.28 for the peripheral venous hematocrit. There was also a significant correlation between the bleeding time and the platelet count in patients with ITP. This study demonstrates that the volume of blood shed at the bleeding time site correlates with the peripheral venous hematocrit and emphasizes the contribution of the hematocrit to primary hemostasis in healthy subjects and patients with bleeding disorders.

Surface area and volume changes during maturation of reticulocytes in the circulation of the baboon

Changes in the surface area and volume of reticulocytes were measured in vivo during late stage maturation. Baboons were treated with erythropoietin to produce mild reticulocytosis. Reticulocyte-rich cohorts of cells were obtained from whole blood by density gradient centrifugation. The cohorts were labeled with biotin, reinfused into the animal, and recovered from whole blood samples by panning on avidin supports. Changes in the surface area, volume, and membrane deformability were measured using micropipettes during the 2 to 6 weeks subsequent to reinfusion. For the entire cohort, the membrane area decreased by 10% to 15% and the cell volume decreased by approximately 8.5%, mostly within 24 hours after reinfusion. Estimates of the cellular dimensions of the reticulocyte subpopulation within this cohort indicated larger reductions in the mean cell area (12% to 30%) and mean cell volume (approximately 15%) of the reticulocytes themselves. Two weeks after reinfusion, the distribution of cell size for the cohort was indistinguishable from that of whole blood. There was evidence of slightly elevated membrane shear rigidity in some reticulocytes before reinfusion, but this slight increase disappeared within 24 hours after reinfusion. These are the first direct measurements of changes in the membrane physical properties of an identifiable cohort of reticulocytes as they mature in vivo.

The effect of disinfection on viability and function of baboon red blood cells

Methods that have been optimized for disinfection of red blood cells before transfusion must be evaluated for their effect on red blood cell viability and function in vitro and in vivo. This study evaluates (1) in vitro effects of Panavirocide treatment and benzoporphyrin (BPD) photosensitization on baboon and human red blood cell parameters and (2) in vivo effects of five disinfectant treatments on 24 h posttransfusion survival and cell lifetimes for baboon red blood cells. The in vitro studies showed that both disinfection methods resulted in a significant reduction in red blood cell potassium, suggesting that intracellular potassium is a sensitive measure of red cell injury during disinfection. The in vivo studies demonstrated significant reductions in the 24 h posttransfusion survival of baboon red blood cells and reductions in cell lifespan treated with a Panavirocide solution, BPD photosensitization and 15 mM nonactivated sodium chlorite. No effects were seen with 250 ppm formaldehyde, aluminum phthalocyanine photosensitization or activated sodium chlorite. These in vivo data showing effects of disinfection treatments support the use of baboons in studying disinfection procedures of autologous red blood cells before attempting studies in humans.

In vivo tracking of platelets: circulating degranulated platelets rapidly lose surface P-selectin but continue to circulate and function

To examine the hypothesis that surface P-selectin-positive (degranulated) platelets are rapidly cleared from the circulation, we developed novel methods for tracking of platelets and measurement of platelet function in vivo. Washed platelets prepared from nonhuman primates (baboons) were labeled with PKH2 (a lipophilic fluorescent dye), thrombin-activated, washed, and reinfused into the same baboons. Three-color whole blood flow cytometry was used to simultaneously (i) identify platelets with a mAb directed against glycoprotein (GP)IIb-IIIa (integrin alpha 11b beta 3), (ii) distinguish infused platelets by their PKH2 fluorescence, and (iii) analyze platelet function with mAbs. Two hours after infusion of autologous thrombin-activated platelets (P-selectin-positive, PKH2-labeled), 95 +/- 1% (mean +/- SEM, n = 5) of the circulating PKH2-labeled platelets had become P-selectin-negative. Compared with platelets not activated with thrombin preinfusion, the recovery of these circulating PKH2-labeled, P-selectin-negative platelets was similar 24 h after infusion and only slightly less 48 h after infusion. The loss of platelet surface P-selectin was fully accounted for by a 67.1 +/- 16.7 ng/ml increase in the plasma concentration of soluble P-selectin. The circulating PKH2-labeled, P-selectin-negative platelets were still able to function in vivo, as determined by their (i) participation in platelet aggregates emerging from a bleeding time wound, (ii) binding to Dacron in an arteriovenous shunt, (iii) binding of mAb PAC1 (directed against the fibrinogen binding site on GPIIb-IIIa), and (iv) generation of procoagulant platelet-derived microparticles. In summary, (i) circulating degranulated platelets rapidly lose surface P-selectin to the plasma pool, but continue to circulate and function; and (ii) we have developed novel three-color whole blood flow cytometric methods for tracking of platelets and measurement of platelet function in vivo.