Transfusion Setting Research Articles

Associations and Prognostic Interactions Between Circulating Levels of Hepcidin, Ferritin, and Inflammatory Cytokines in Primary Myelofibrosis.

AbstractAbstract 2831 Background and Aims:Primary myelofibrosis (PMF) is characterized by ineffective erythropoiesis, an underlying inflammatory state and potentially, iron overload in the setting of red cell transfusions. The potential interaction between these clinical variables and assessment of their independent prognostic contribution, if any, is of interest within the context of well established prognostic parameters including the DIPSS-plus model and increased circulating levels of inflammatory cytokines (J Clin Oncol. 2011 Apr 1;29(10):1356–63). Consequently, we studied the relationship between circulating levels of hepcidin (a surrogate for inflammation, iron stores and ineffective erythropoiesis), ferritin (iron stores and inflammation), red cell transfusion need (ineffective erythropoiesis) and soluble inflammatory cytokine levels in PMF patients. Methods:The diagnosis of PMF was according to WHO criteria. Inclusion in this study required availability of archived plasma, bone marrow biopsy, and cytogenetic information at the time of first referral. Plasma total hepcidin levels were measured by ELISA (USCN Life Sciences, Wuhan, China). Serum ferritin was measured as part of routine clinical assessment (normal range: males: 24–336 mcg/L; females: 11–307 mcg/L). Concentrations of plasma cytokines were analyzed in duplicate by using Multiplex Bead-Based Luminex technology (Invitrogen, Carlsbad, CA). Results:Two hundred and three PMF patients met the above stipulated criteria; 136 (67%) were males and the median age at referral was 63 years (range 17–83). Their dynamic international prognostic scoring system (DIPSS)-plus risk categorization was: low-risk 22 (11%), intermediate-1 26 (13%), intermediate-2 85 (42%) and high-risk 70 (34%).Hepcidin levels (median 156279 pg/mL; range 8082–2088002) were strongly correlated with serum ferritin (n=146; median 207 mcg/L; range 14–5367) (r2=0.43, p <0.0001). Both were directly correlated with red cell transfusion need and age, and inversely with hemoglobin level (all p <0.05); however, there was no correlation with increased levels of inflammatory cytokines (>3 standard deviation above mean of normal controls for IL-2 and/ or IL-8) (p>0.05).At a median follow up of 35 months, 104 (51%) deaths and 18 (9%) leukemic transformations were recorded. In univariate analysis, increased levels of hepcidin (HR=2.0; p=0.0006) and ferritin (HR=2.7; p<0.0001) were predictive of inferior overall survival and this significance was sustained during multivariable analysis that included either increased inflammatory cytokine levels (HR=3.2 and 2.7, respectively) or transfusion need (HR=1.7 and 2.2, respectively) as covariates. When all 4 variables (i.e. increased levels of hepcidin, ferritin, inflammatory cytokines and transfusion need) were considered together in the Cox model, only increased inflammatory cytokine levels retained their prognostic significance (HR=2.7; p=0.0046). Furthermore, neither increased ferritin nor increased hepcidin levels were prognostically significant for overall survival when tested either individually or together against the DIPSS-plus model (p>0.05).In univariate analysis, increased hepcidin level, but not increased ferritin or transfusion need, was predictive for inferior leukemia-free survival (HR=2.8; p=0.04) and this significance was sustained in multivariable analysis that included either cytogenetic risk categories (very-high risk versus high-risk versus other) (HR=2.7; p=0.046) or thrombocytopenia (platelet count <100 × 109/L) (HR=2.7; p=0.047) as covariates. Conclusions:Circulating levels of hepcidin and ferritin are highly correlated variables in PMF and appear to provide redundant prognostic information for overall survival in this setting. The lack of correlation with inflammatory cytokines suggests that ineffective erythropoiesis may be the common link for their apparent prognostic value noted during univariate analysis. In contrast to inflammatory cytokines, neither hepcidin or ferritin levels were useful as a complement to the DIPSS-plus prognostic model in the current analysis. The relationship between hepcidin and leukemia-free survival is intriguing however the pathogenetic mechanism remains obscure and needs confirmation in additional patients. Disclosures:No relevant conflicts of interest to declare.

Solving the Dilemma of Prevention of Red Cell Alloimmunization

Evaluation of: Stephen J, Cairns LS, Pickford WJ, Vickers MA, Urbaniak SJ, Barker RN. Identification, immunomodulatory activity and immunogenicity of the major helper T cell epitope on the K blood group antigen. Blood 119(23), 5563-5574 (2012). Alloimmunization to blood group antigens is a major concern in transfusion medicine. This occurs when antigen-mismatched blood is transfused into a recipient lacking a red blood cell antigen that is expressed on the donor red blood cells. Alloimmunization in this case can result in future problems in finding compatible blood for transfusion and can cause hemolytic transfusion reactions. Alloimmunization can also occur in instances where a mother lacks a red blood cell antigen that is carried by the fetus. In these cases, alloimmunization can result in an antibody that can cross the placenta and cause moderate-to-severe problems in the fetus or newborn due to hemolytic anemia and/or inhibition of hematopoiesis. This is called hemolytic disease of the fetus and newborn. Stephen et al. describe a unique approach to producing a peptide tolerogen to prevent alloimmunization to a specific blood group antigen, K, in the Kell blood group system. They identify an immunodominant K peptide and use this peptide to show that it strongly stimulates human T helper cells from K-immunized people in vitro and that it shows efficacy when used as a nasal tolerogen to suppress immunization with K protein in a mouse model. These results open the door for therapies aimed at the prevention and/or treatment of alloimmunization in both a transfusion setting and, importantly, in hemolytic disease of the fetus and newborn.

Nitric oxide, hemolysis, and the red blood cell storage lesion: interactions between transfusion, donor, and recipient

The putative ‘red blood cell (RBC) hypothermic storage lesion’ is the focus of intense interest and investigation in transfusion medicine . Owing to detrimental changes taking place during a period of up to 42 days, the RBC ability to sustain normal functionality after transfusion can become compromised. While our understanding of the RBC storage lesion has been advanced by a myriad of historical and more recent studies1-10, the clinical significance of transfusing “old blood” remains unclear. In this issue of Transfusion, Yu et al11, discuss the possible outcomes of transfusing stored versus fresh mouse RBCs into syngeneic susceptible hosts, that is mice with diabetes. They demonstrate that transfusion of stored RBCs or supernatants from stored RBCs can induce systemic hypertension and vasoconstriction in mice suffering endothelial dysfunction (diabetic mice), and that transfusion-induced vasoconstriction can be prevented by nitric oxide (NO) inhalation or oxidation of supernatants from stored RBCs. They correlate the hypertensive effects with hemolysis of stored RBCs and NO scavenging by cell-free hemoglobin. Yu and colleagues’ study supports recent mechanisms for the putative RBC storage lesion related to red cell hemolysis and inactivation of endothelial nitric oxide1,3,12,13 that may in part contribute to transfusion-related multi-organ injury, particularly in the setting of massive transfusion. Their work highlights the interaction between the age of banked blood and the health of the blood recipient (susceptible host), as well as characterizes the potential therapeutic use of NO to ameliorate severe outcomes in patients suffering from endothelial dysfunction caused by transfused blood hemolysis.

Rationaler Einsatz von Blutprodukten - Reduzierung des Blutprodukteverbrauchs durch ein modernes Gerinnungsmanagement

Evaluating the patient's individual bleeding history with a standardized questionnaire, using "point-of-care" - methods for coagulation analyses and providing autologous transfusion techniques are preconditions of a modern coagulation management. Therapy of coagulopathic patients should be based on structured hemotherapy algorithms. Surgical haemostasis and the maintenance of the basic conditions for haemostasis are elementary requirements for an effective therapy. In cases of diffuse bleeding, early antifibrinolytic therapy should be considered. Coagulation factor deficiencies should be corrected "goal-directed" using coagulation factor concentrates. Transfusion of fresh frozen plasma is only indicated in the clinical setting of massive transfusions. DDAVP and transfusion of platelet concentrates are options to optimize primary haemostasis. In cases of on-going bleeding, recombinant activated coagulation factor VII represents an option for "ultima-ratio" therapy.

Mechanisms behind adhesive erythrocytes in sickle‐cell disease

Erythrocytes containing primarily hemoglobin S (SS RBCs) are abnormally adherent to a number of ligands, including normal constituents of the extracellular matrix as well as those present on the surfaces of other blood cells and endothelial cells. However, SS RBCs are not really very different from normal (AA) RBCs, except that they are younger. In general, they express the same range of adhesion receptors, and the levels of expression of these receptors, although increased in some cases, are not sufficient to explain the difference between the adhesivity of SS and AA RBCs. However, SS RBCs have activated adhesion receptors, and the signaling pathways responsible for this activation are also upregulated in SS RBCs. In addition, SS RBCs convey different extracellular signals, which are also likely to affect their adhesion to other blood cells and endothelial cells. Together, SS RBCs induce cell–cell interactions mediated by the B‐CAM/LU, ICAM4 (LW), CD44 (In), CD47, α4β1 integrin, and CD36 adhesion molecules on SS RBCs with target ligands on leukocytes and endothelial cells. Other, as yet unidentified cell surface moieties on SS RBCs are probably also responsible for SS RBC interactions with P‐selectin. Interestingly, at least some of these RBC adhesion receptors may also mediate adhesion and adverse physiologic events in the setting of transfusion of stored normal RBCs. Therefore, understanding the mechanisms behind SS RBC adhesion may offer opportunities for improving both therapy of sickle‐cell disease as well as transfusion practices.

Transfusion Increases the Risk for Vasoplegia After Cardiac Operations

Perioperative vasoplegia is associated with increased morbidity. Red blood cell (RBC) transfusion increases plasma concentrations of inflammatory mediators, possibly contributing to the development of vasoplegia. We investigated the prevalence of mild and profound postoperative vasoplegia, identified factors associated with its development, and examined the role of RBC and component transfusion on the occurrence of postoperative vasoplegia. Between January 1, 2000, and January 1, 2007, 25,960 patients underwent on-bypass cardiac surgical procedures. The incidence of vasoplegia was defined as (1) mild vasoplegia requiring norepinephrine infusion for blood pressure support on the day of operation and postoperative day 1, and (2) profound vasoplegia requiring vasopressin, with or without concomitant norepinephrine infusion, on the day of operation and postoperative day 1. Separate logistic regression models were used to model risk factors for development of mild and profound vasoplegia. RBC transfusion increased risk-adjusted odd ratios (ORs) of developing mild vasoplegia (1.07 [95% confidence limits (CL), 1.05, 1.10]; p<0.001) and profound vasoplegia (1.38 [1.31, 1.46] p<0.001). The risk-adjusted ORs (95% CL) for mild vasoplegia and profound vasoplegia were similarly increased by fresh-frozen plasma (OR, 1.24 [1.10, 1.41], p<0.001; and OR, 1.20 [1.13, 1.29], p<0.001) and platelet transfusion (OR, 1.39 [1.25, 1.54], p<0.001; and OR, 1.22 [1.14, 1.31], p<0.001), respectively. Red blood cells, fresh-frozen plasma, and platelet transfusion increased the prevalence of vasoplegia. RBC transfusion exhibited a dose-dependent response for developing vasoplegia with each RBC unit transfused. Further investigation is necessary to determine whether prophylactic use of vasopressor support in the setting of transfusion can ameliorate risk and effect outcomes.

New Molecular Players in the Great Fluid Debate

Anesthesiologists, it seems, will never agree on the optimal fluid resuscitation protocols for critically ill patients. The “Great Fluid Debate” is the anesthesiology equivalent of fashion in the art world—lots of opinions, with historical cyclic swings about what is “in.” Competing fluid resuscitation strategies will always be points for discussion and disagreement, unfortunately. Getting an answer about the best resuscitation strategies is understandably difficult because of heterogeneity in outbred humans, heterogeneity of complex clinical processes such as hemorrhage, and expense of clinical studies that require long-term follow-up data. Many clinical studies on massive hemorrhage focus on survival as the major end point of analysis after fluid resuscitation; rightly so, but survival is affected by many factors in resuscitation of critically ill patients, making it difficult to gain insight into fluid administration best practices. In this issue of Anesthesia & Analgesia, Kozar et al. report their work comparing plasma versus lactated Ringer (LR) solution resuscitation in a rat hemorrhagic shock model. Resuscitation with plasma in clinical massive hemorrhage is controversial, and many trauma centers have withheld aggressive plasma resuscitation because of concerns about the risk of transmitting infection and risks of transfusion-associated lung injury. A trend toward increased early use of plasma for massive hemorrhage was prompted by recent observations in civilian and battlefield trauma settings that early use of plasma is associated with increased survival. For example, patients presenting to a Los Angeles County Hospital level I trauma center over a 6-year period were more likely to survive massive transfusion if the fresh frozen plasma/red blood cell ratio was high, up to a ratio of 1:3. Five other studies with similar conclusions are cited in the Kozar et al. report (1–5). All of these influential studies are retrospective, with all the usual caveats inherent in retrospective work, and none of the studies can address mechanism of survival because of the nature of the data. The literature dealing with massive hemorrhage has been plagued by the lack of markers (laboratory data) that reliably guide prognosis or quantify the value of resuscitation maneuvers. In particular, static clotting times are difficult to interpret in the setting of massive hemorrhage and transfusion, and likely a matrix of laboratory studies and modeling will be necessary to guide therapy. Enter potential new markers and monitors of hemorrhagic shock and resuscitation from hemorrhagic shock: the endothelial glycocalyx and syndecan-1. The endothelial glycocalyx is a complex barrier, enriched in proteoglycans of the syndecan and glypican families as well as glycosaminoglycan attachments of heparan, dermatan and chondroitin sulfates, and hyaluronan.The endothelial glycocalyx regulates movement across blood vessel walls: glycocalyx damage or shedding results in protein extravasation from the circulation, contributing to end-organ edema, and also exposes the endothelium to pathologic white cell and platelet adhesion. Glycocalyx shedding is an important acute underlying pathologic factor in reperfusion injuries, systemic inflammatory response, trauma, sepsis, and chronically in vasculopathies, but no clinical trials directed at the glycocalyx have been performed. Syndecans are ubiquitous transmembrane proteoglycans that interact with the extracellular matrix, growth factors, and chemokines to regulate adhesionand growth factor-mediated signaling pathways. Syndecans are emerging as integrators of the environments outside of the cell with signaling inside the cell. In the Kozar et al. study, the hemorrhagic shock model imposed a mean arterial blood pressure (MAP) of 30 mm Hg for 90 minutes, then rats were resuscitated to MAP 80 mm Hg with either LR solution or plasma, and normal MAP was maintained for 2 hours. Venules from the small bowel mesentery were examined for glycocalyx morphology. Ninety minutes of shock resulted in clear loss (shedding) of the glycocalyx and decreased expression of syndecan-1 message, unchanged by resuscitation with LR solution, but significantly restored by plasma. Similarly in the lung, the normally abundant syndecan protein in the alveolar wall disintegrated as a function of shock, was unchanged by LR solution, but significantly restored by plasma resuscitation. Gross lung pathology was also improved by plasma. The rapidity of restoration of endothelial and pulmonary histologic appearance is remarkable, and sets the stage for examination of the effects of timing of plasma resuscitation on end-organ recovery. This study certainly does not close the knowledge gap necessary to engender full confidence in early plasma resuscitation for hemorrhagic shock, but it does point to syndecan-1 and the glycocalyx as a whole as potential targets of therapies in shock patients. Similar to all good From Research & Development, Organovo, Inc., San Diego, California.

Effects of use of riboflavin and ultraviolet light for pathogen inactivation on quality of platelet concentrates

Pathogen inactivation in blood and blood products is one of the major means to achieve a zero risk blood supply and improve transfusion safety. Riboflavin (vitamin B2) activated by ultraviolet (UV) light, produces active oxygen which damages cell membrane and prevents replication of the carrier of diseases (viruses, bacteria, protozoa) in all blood products. The aim of this study was to establish the influence of the process of pathogens photoinactivation using riboflavin and UV rays on the biochemical and functional characteristics of platelet concentrates prepared from "buffy coat". The examination included 80 platelet concentrates prepared from "buffy coat", which was separated from whole blood donated by voluntary blood donors around 6 hours from the moment of collection. Concentrates were pooled, filtered and separated unton two groups: one consisted of 10 control units and the other of 10 examined units (pooled platelet concentrates). Examined units of the platelets were treated by riboflavin (35 mL) and UV rays (6.24 J/mL, 265-370 nm) on Mirasol aparature (Caridian BCT Biotechnologies, USA) in approximate duration of 6 min. A total of 35 mL of saline solution was added to the control units. The samples for examining were taken from the control and examined units initially (K0, I0), after the addition of saline (K1) and riboflavin (I1), after illumination (I2), first day of storage (K3, I3) and the fifth day of storage (K4, I4). The following parameters were measured: platelet count and platelet yield, residual erythrocyte and leukocyte count, pH, pO2, pCO2 and bacterial contamination. All the measured parameters showed a statistically significant decrease comparing to K0 and I0; all the results of the first day of platelet storage showed statistically significant decrease comparing to K1 and I1, and all the results of the fifth day of platelet storage (K4, I4) showed a statistically significant decrease comparing to K1 and K3 and to I1 and I3. There was no the mentioned difference in the measured parameters between K4 and I4 (the end of storage--the fifth day). All the platelet units were sterile till the seventh day, when the investigation ended. Platelet concentrates inactivated by riboflavin and UV rays (Mirasol PRT sistem, Caridian BCT, USA) keep all the characteristics assessed by the Guide to the preparation, use and quality assurance of blood components (Council of Europe), during the whole storage period (five days). The obtained data were correlated with existing up to date literature and demonstrated that Mirasol treated platelets were safe and could be incorporated effectively in the routine blood bank and transfusion setting.

Guidelines on the use of irradiated blood components prepared by the British Committee for Standards in Haematology blood transfusion task force

Search terms included: Transfusion-associated graft-versus-host disease, Transfusion-associated graft-versus-host, TA-GvHD. The last guideline covering this topic was published in 1996 (British Committee for Standards in Haematology (BCSH) Blood Transfusion Task Force, 1996. The writing group produced the new draft guideline, which was subsequently revised by consensus by members of the Haemato-oncology and Blood Transfusion Task Forces of the BCSH. The guideline was then reviewed by a sounding board of approximately 100 UK haematologists, the BCSH and the committee of the British Society for Haematology and amended, again by consensus. Criteria used to quote levels and grades of evidence are according to the GRADE system (Guyatt et al, 2006). Strong recommendations (grade 1, ‘recommended’) are made when there is confidence that the benefits either do or do not outweigh the harm and burden and costs of treatment. Where the magnitude of benefit or not is less certain a weaker grade 2 recommendation (‘suggested’) is made. Grade 1 recommendations can be applied uniformly to most patients whereas grade 2 recommendations require judicious application. The quality of evidence is graded as A (high quality randomized clinical trials), moderate (B) or low (C). This publication reports the key recommendations of the Writing Group. It is also accessible at http://www.bcshguide lines.com.

Continuous Transversus Abdominis Plane (TAP) Block Catheters in a Combat Surgical Environment

The ongoing conflict in Afghanistan continues to generate a large number of complex trauma injuries and provides unique challenges to military anesthetists working in forward field hospitals. We report successful use of ultrasound-guided continuous transversus abdominis plane (TAP) block in two Afghan war casualties who sustained major trauma with coagulopathy. The use of bilateral continuous TAP blocks following major thoracoabdominal trauma in a combat environment is unique in the literature. Case report. The acute perioperative outcomes of two Afghan civilian patients were improved with bilateral continuous TAP blocks. Multiple benefits shared by both patients included early extubation, excellent analgesia, and minimal post-operative morphine requirements despite the setting of a massive blood transfusion and coagulopathy. A continuous TAP block technique can be utilized to provide excellent analgesia following major abdominal surgery when neuraxial anesthesia is contraindicated. The TAP block's ease of placement under ultrasound guidance makes this technique particularly useful in the austere battlefield hospital environment.

The effect of plasma transfusion on morbidity and mortality: a systematic review and meta‐analysis

Plasma transfusion is increasingly performed without clear consensus on indications. We systematically reviewed the literature to summarize the available evidence regarding the benefits and harms of plasma transfusion in common clinical settings. We searched electronic databases from inception through August 2009. Eligible studies enrolled adult patients transfused with plasma and compared to a control group. Paired reviewers independently assessed studies for eligibility and extracted quality and outcome data. Thirty-seven studies met eligibility criteria, most of which were observational. In patients undergoing massive transfusion, plasma infusion at high plasma : red blood cell ratios was associated with a significant reduction in the risk of death (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.24-0.60) and multiorgan failure (OR, 0.40; 95% CI, 0.26-0.60). However, the quality of this evidence was very low due to significant unexplained heterogeneity and several other biases. In a single retrospective study, plasma transfusion was associated with reduced mortality in anticoagulated patients with intracranial hemorrhage (OR, 0.29; 95% CI, 0.09-0.98). In patients undergoing surgery without massive transfusion, plasma infusion was associated with a trend toward increased mortality (OR, 1.22; 95% CI, 0.73-2.03). Plasma transfusion was associated with increased risk of developing acute lung injury (OR, 2.92; 95% CI, 1.99-4.29). Very-low-quality evidence suggests that plasma infusion in the setting of massive transfusion for trauma patients may be associated with a reduction in the risk of death and multiorgan failure. A survival benefit was not demonstrated in most other transfusion populations.

Thromboelastometry to Guide Recombinant Activated Factor VII Therapy for Postoperative Refractory Intracranial Bleeding

Thromboelastometry to Guide Recombinant Activated Factor VII Therapy for Postoperative Refractory Intracranial Bleeding

Fatal hemolytic disease of the fetus and newborn associated with anti‐Jra

Jr(a) is a high-prevalence red cell (RBC) antigen. The clinical significance of anti-Jr(a) is controversial. When hemolytic disease of the fetus and newborn (HDFN) occurred, most reported cases were clinically mild. We report the first case of fatal HDFN due to anti-Jr(a). A 28-year-old Caucasian woman with transfusion history was monitored at the 29th week of pregnancy (G4P1). An ultrasound scan showed fetal cardiomegaly and hepatomegaly. An antibody directed against a high-prevalence antigen was detected, but without conclusive identification. An emergency cesarean section was performed at the 36th week. The newborn was hydropic and showed severe anemia. Death occurred 30 hours after birth. Serologic methods were performed to investigate the mother's RBCs and serum. An in vitro functional cellular assay and semiquantitative measurement of anti-Jr(a) were used to determine the clinical significance of the antibody. Anti-Jr(a) was identified in the serum and Jr(a-) phenotype was confirmed. The anti-Jr(a) titer was 1024, with predominant immunoglobulin (Ig)G1 and minor IgG4 subclasses. The functional cellular assay was consistent with an antibody unlikely to cause HDFN. Semiquantitative measurement of anti-Jr(a) showed a reactivity equivalent to a 25 IU per mL (5 microg/mL) concentration of anti-D, a value associated with a significant risk of HDFN. This is the first documented case of fatal HDFN due to anti-Jr(a). Therefore, we recommend close monitoring of pregnant women with a high-titer anti-Jr(a), especially those with an incompatible transfusion history and/or multiple pregnancies. This case report provides new arguments about the clinical significance of anti-Jr(a) in the transfusion setting.

Antigen‐antibody combination assays for blood donor screening: weighing the advantages and costs

Antigen‐antibody combination assays for blood donor screening: weighing the advantages and costs

Valid Comparisons of Antifibrinolytic Agents Used in Cardiac Surgery

Bleeding is a major source of morbidity and mortality after cardiac surgical procedures. Patients who return to the operating room for bleeding have a 4-fold increase in mortality and a similar increase in the rate of sternal infection. The significance of this issue is underscored by the fact that patients undergoing cardiac surgery consume up to 30% of the nation’s blood supply. During massive hemorrhage resulting from trauma, the life-saving benefits of blood transfusion are well documented. However, in the more common setting of elective blood and blood component transfusions in intensive care units using arbitrary transfusion triggers, the benefits of transfusion are not well established and may have a net negative influence on outcomes. Indeed, the overt dangers of transfusion are unequivocal (hepatitis C, HIV, fever, infection, increased costs, transfusion reaction), and evidence of the covert dangers of blood transfusion (prolonged intensive care unit stay, increased mortality, increased morbidity) after cardiac surgery is persuasive.1 Because both bleeding itself and the transfusions administered to compensate for blood loss have an untoward impact on outcomes, there is strong motivation to decrease the occurrence of bleeding associated with cardiac surgical procedures in the first place. In this regard, the Society of Thoracic Surgeons Workforce on Evidence Based Surgery, in conjunction with the Society of Cardiovascular Anesthesiologists, recently published a comprehensive guideline outlining appropriate methods for blood conservation in cardiac surgery.2 Article p 2801 Recently, Mangano et al published the short-term3 and longer-term4 results of the same observational study comparing the 3 antifibrinolytic agents available for use in cardiac surgical patients (aprotinin, e-aminocaproic acid [EACA], and tranexamic acid [TXA]) with control patients who received neither of these agents. These studies caused considerable concern among cardiac surgeons and regulatory agencies because the authors concluded that aprotinin was associated with a …

Twenty-four mini-pool HCV RNA screening outside a blood transfusion setting: Results of a 2-year prospective study

The usefulness of 24 mini-pool hepatitis C virus (HCV) RNA screening was evaluated in a 2-year prospective study carried out on a total of 6432 consecutive anti-HCV negative specimens in a routine diagnostic laboratory setting. A total of 268 mini-pools were tested using an automated commercial PCR assay for qualitative detection of HCV RNA, with a lower limit of detection of 50 IU/ml. Eighteen (0.28%) anti-HCV negative/HCV RNA positive serum samples obtained from 12 patients (all intravenous drug users), were detected. Ten patients responded to an invitation for follow-up testing. Five, three and one patient seroconverted in the first, second and third follow-up sample, respectively. One patient had not seroconverted by the end of the study period. The interval between the first HCV RNA positive sample and the first anti-HCV positive samples was 24–192 days. The costs of detecting a single anti-HCV negative/HCV RNA positive sample and a single anti-HCV negative/HCV RNA positive patient using the 24 mini-pool HCV RNA screening strategy were estimated to be around €643 and 965, respectively. It was shown that screening for HCV infection using the 24 mini-pool HCV RNA screening strategy can also be both useful and cost effective outside a blood transfusion setting.

CD47 Glycoprotein Interacts with p4.1R and p55 in the Erythrocyte.

CD47 is a 47–50kDa membrane glycoprotein with 5 known isoforms. The role of CD47 within the erythrocyte membrane remains the subject of much research and debate though we recently provided evidence that CD47 may function as an inducer of eryptosis (Head et al, 2005). As both a cytoskeletal linked fraction and a smaller membrane diffuse fraction of CD47 exists, it is most likely that there are a number of protein species that are able to bind to CD47 at its cytoplasmic face. Our research has focused on a study of the molecular interactions of erythrocyte CD47 with erythrocyte membrane skeletal proteins protein 4.1R (p4.1R), protein 4.2 (p4.2) and p55. Here we demonstrate the ubiquitous expression of all CD47 isoforms in haemopoietic cells and tissues using basic and real-time PCR. Via immunoprecipitation of CD47 from mature erythrocyte membranes using the anti-CD47 mAb BRIC-126, yeast two-hybrid analysis and in vitro co-immunoprecipitation of 35[S] labelled peptides in a cell-free translation procedure, a novel ternary complex involving CD47, p55 and p4.1R has been indicated. More specifically, the potential interaction between p55/p4.1R and the cytoplasmic face of CD47 has been localised to the PDZ and FERM domain of these proteins respectively. Though research suggests p4.2 provides the major cytoskeletal attachment of CD47 (Bruce et al, 2002; Mouro-Chanteloup et al, 2003), a direct interaction between CD47 and p4.2 was not suggested by our study and remains undemonstrated. We continue to further the evidence for a functional role of CD47 in eryptosis. We propose p4.1R links CD47 to the apoptotic machinery of the cell and suggest a mechanism whereby cytoskeletal rearrangement and PS exposure occurs. 4.1null cells have been obtained and are currently being investigated. Further characterisation of the eryptotic pathway may offer insight into potential therapies for erythroleukaemia characterised by resistance of the erythroid lineage to apoptosis. This work has equal significance in the stabilization of red cell preparations in the blood transfusion setting.

Systemic Thromboses after Cardiopulmonary Bypass: Is It Thrombin or Antithrombin?

Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. yiandoc@hotmail.comI thank Drs. Tanaka and Sniecinski for their comments on our two reports of systemic thrombosis after cardiopulmonary bypass associated with aprotinin.1,2They point out the possible role of antithrombin deficiency in these scenarios: This is applicable, given the settings of endocarditis, disseminated intravascular coagulation, and prolonged cardiopulmonary bypass.1,2In the presence of antithrombin deficiency, overall thrombin production is increased.3This thrombin excess could be a factor in the rapid development of systemic thrombosis described.1,2How do we integrate these observations into clinical practice? Clearly, we still lack adequate data to proceed. Bolus heparin therapy in the setting of aprotinin monitored with appropriate activated clotting time is an established standard for cardiopulmonary bypass, including deep hypothermic circulatory arrest, as the authors point out in their footnote. Furthermore, we have a large experience with this technique, including in deep hypothermic circulatory arrest.4–6To my knowledge, there is no case report of this phenomenon with bolus heparin therapy titrated to heparin level. Of course, on the basis of case reports, no comparisons can be inferred between these two standards of care with respect to this kind of event.Systemic thrombosis after cardiopulmonary bypass is very uncommon in the presence of standardized heparin therapy. It has also been reported in the pediatric population and in the presence of aminocaproic acid.7,8A common feature in these reports is that the onset of thrombosis is shortly after heparin reversal with protamine, often in the setting of blood component transfusion to correct ongoing bleeding.The exact etiology of this rare, but catastrophic event is probably multifactorial, including genetic factors such as factor V Leiden.9Antithrombin deficiency may be another factor in this multifactorial etiology. The role of aprotinin is still to be elucidated, because there is recent evidence of an association with thrombotic risk after cardiopulmonary bypass.10This area of endeavor is limited not only by a rare incidence and complex etiology, but also by a lack of real-time objective coagulation monitoring data. This information would allow analysis of the coagulation/anticoagulation imbalance to localize the lesion and direct further inquiry.The role of antithrombin deficiency should also be interpreted in light of the thrombin inhibitor. Until recently, heparin, an indirect thrombin inhibitor, was the main anticoagulant for cardiopulmonary bypass. This will certainly shift in the future, given the arrival of bivalirudin, a direct thrombin inhibitor, as a clinical alternative to heparin for cardiac surgery with and without cardiopulmonary bypass.11,12Drs. Tanaka and Sniecinski have correctly highlighted antithrombin deficiency as a possible component in the etiology of systemic thrombosis after cardiopulmonary bypass. The continuing incidence of these rare, but catastrophic cases highlights the clinical necessity for better data, perhaps in the form of an international registry. This would provide a platform for further clinical trials to refine our coagulation management of cardiopulmonary bypass and improve perioperative outcomes for our patients.Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. yiandoc@hotmail.com

Acute hepatitis B virus window‐period blood donations detected by individual‐donation nucleic acid testing: a report on the first two cases found and interdicted in Spain

Mathematical models predict that, in Spain, a significant number of blood units will be obtained during the window period of the hepatitis B virus (HBV) infection. Routine nucleic acid testing (NAT) on individual blood units may provide experimental data to evaluate such a theoretical risk. Between February and July 2005, a total of 34,631 individual units were screened for HBV DNA by a multiplex transcription-mediated amplification (TMA) test. Units that repeatedly reacted in the test, but did not react for HBV surface antigen (HBsAg), were submitted to additional testing by both molecular and conventional assays, and the donors were recalled for follow-up studies and the collection of clinical and epidemiologic data. Confirmatory testing and follow-up studies identified 2 blood units donated during the HBV infection window period (1/17,316 units studied). Sequencing of amplification products obtained by nested polymerase chain reaction (n-PCR) revealed two HBV strains from genotypes D/ayw3 and F/adw4q-, but did not identify HBsAg mutants. The HBV DNA concentration in the index donations was estimated to be below the n-PCR detection level (180 IU/mL), in both cases. One donor developed acute hepatitis 2 months after donating blood, but the other remained asymptomatic and displayed normal alanine aminotransferase levels at follow-up. The HBV infection window period is a real issue in the setting of Spanish blood transfusions. NAT of individual units by TMA would make a significant contribution to improving the safety of the blood supply in Spain. Additional studies involving a larger number of units and longer periods of time are required, however, to ascertain the true incidence of the problem in this country.

LW protein: a promiscuous integrin receptor activated by adrenergic signaling

The LW blood group antigen glycoprotein, although part of the Rh macromolecular complex, is nonetheless a member of the intercellular adhesion molecule (ICAM) family. Thus, while it is only rarely clinically important in the setting of transfusion and pregnancy, LW is likely to contribute to red cell adhesion in a variety of settings, including during hematopoiesis, as well as in vascular disorders. The best documentation of a pathophysiological role for LW in human disease is in sickle cell disease, where it contributes to red cell adhesion to endothelial cells and the development of vaso-occlusion, the hallmark of that disease. LW may also contribute to other intravascular processes, such as both venous and arterial thrombosis, due to its ability to interact with both activated platelets as well as leukocytes. The evidence that LW itself can undergo activation on red cells holds promise that pharmacotherapeutic maneuvers may be found to prevent such pathophysiologic interactions.