Objective To observe the clinical efficacy and adverse reactions of CSP in patients with surgical hemorrhage. Methods A prospective, double-blind, randomized clinical trial was conducted on surgical patients with related bleeding to assess the hemostatic function of CSP compared with RTP. The primary outcomes measured were drainage volume, platelet counts, and Thrombelastography-maximum amplitude. Secondary outcomes included hospital stays, the intensive care unit stays and medical cost. Results A total of 62 patients were completed the final clinical observation. There were 31 cases in each of the CSP group and RTP group. Within 1~12 hours, 13~24 hours, 25~48 hours, and 49~72 hours after platelet transfusion, drainage volume: 8.5 mL/h vs 20.83 mL/h, 0.52 mL/h vs 5.0 mL/h, 3.5 mL/h vs 5.0 mL/h, 0.63 mL/h vs 4.1 mL/h. platelet counts: 58×10 ⁹/L vs 79×10 ⁹/L, 54×10 ⁹/L vs 77×10 ⁹/L, 63×10 ⁹/L vs 75×10 ⁹/L, 66×10 ⁹/L vs 79×10 ⁹/L. TEG-MA: 50.1 mm vs 52.0 mm, 50.1 mm vs 54.8 mm, 53.0 mm vs 56.6, 56.0 mm vs 53.2 mm. There were no overall differences between the two groups by Generalized Estimating Equations at different times ( P _Drainage=0.933, P _PLTcounts=0.473, P _TEG-MA=0.246). The secondary outcomes (hospital stays, ICU stays, medical cost, discharge outcome) were no differences between the CSP group and RTP group ( P>0.05). There were no significant differences in adverse platelet transfusion events between the groups ( P>0.05). Conclusion CSP and RTP have equivalent efficacy and safety in the treatment of surgical hemorrhage. This trial provides reliable evidence to support the clinical application of CSP.

The big data of unexpected red blood cell antibody and Rh blood group distribution in Chinese population shows that the proportion of anti-RhCE antibody (41.94%) is 4.7 times higher than that of anti-RhD antibody (8.93%) among unexpected antibodies in hospitalized patients. In random blood transfusion, the probability of RhCE antigen mismatch (25.16%) is 51.4 times higher than that of RhD antigen mismatch (0.49%). These data indicate that RhCE antigen mismatch is the main risk for Chinese transfusion patients, and establishing RhCE antigen matching transfusion strategies suitable for Chinese patients is crucial for transfusion safety.

In May 2025, the Association for the Advancement of Blood and Biotherapies (AABB) and the International Collaboration for Transfusion Medicine Guidelines (ICTMG) jointly released the updated Guidelines for Platelet Transfusion. Based on 21 Randomized Clinical Trials (RCTs) and 13 high-quality observational studies, the guideline adopted the Grading of Recommendations Assessment Development and Evaluation (GRADE) system for evidence analysis, and established the "restrictive platelet transfusion strategy" as the core, aiming to promote the standardization and homogenization of global platelet transfusion practices. The guideline has a wide scope of application, covering different populations such as adults, children, and neonates, including patients with hematological diseases, stem cell transplant recipients, perioperative patients, dengue fever patients, and those undergoing invasive procedures. It sets minimal important differences (MIDs) thresholds for three key outcomes—mortality (2%), grade 2-4 bleeding (20%), and grade 3-4 bleeding (5%)—for evidence certainty grading. In terms of key recommendations, it clarifies strong recommendations with high/moderate certainty of evidence (e.g., transfusion for patients with non-bleeding thrombocytopenia undergoing chemotherapy or allogeneic stem cell transplantation when platelet count<10×10 ⁹/L; transfusion for neonates with consumptive thrombocytopenia without severe bleeding when count<25×10 ⁹/L; no transfusion for dengue fever patients without major bleeding, etc.) and conditional recommendations with low/very low certainty of evidence (e.g., conditional non-recommendation of prophylactic transfusion for adult patients undergoing autologous stem cell transplantation; conditional transfusion for adult patients undergoing central venous catheterization when count<10×10 ⁹/L, etc.). Meanwhile, it elaborates on common platelet transfusion reactions and their risks, such as allergic reactions, febrile reactions, and transfusion-related acute lung injury (TRALI). By lowering transfusion thresholds and refining risk stratification, the guideline can reduce unnecessary transfusions and related adverse reactions, and alleviate the shortage of platelet resources. In the future, it is necessary to further supplement evidence-based evidence in fields such as cardiopulmonary bypass and interventional radiology, and explore technologies like in vitro induced differentiation of platelets and universal engineered platelets to optimize transfusion practices.

Objective To compare the effectiveness of the anti-human globulin microcolumn agglutination method and the traditional saline medium test tube method in detecting unexpected antibodies in red blood cells, and to explore the value of using both methods in parallel for antibody screening. Methods We retrospectively investigated 2 518 samples from the Shanghai Blood Center, which underwent unexpected antibody screening between January 2014 and December 2024. Our study focused on the detection of eight types of antibodies (anti-M, anti-Le ^a, anti-Mur, anti-Le ^b, anti-P ₁, anti-Di ^a, anti-Fy ^b, and anti-S) using the saline test tube method. Cases where both the saline medium test tube and the anti-human globulin microcolumn agglutination methods were used in parallel were selected for comparison. Data were analyzed using SPSS 22.0, and differences were assessed with McNemar's test (paired chi-square test). Results The detection rates for the antibodies were as follows: anti-M (96% by the saline method vs. 62% by the microcolumn method), anti-Le ^a (60% vs. 97% ), anti-Mur (60% vs. 97%), anti-Le ^b (84% vs. 70% ), anti-P ₁ (89% vs. 40%), anti-Di ^a (10% vs. 99% ), anti-Fy ^b (4% vs. 88% ), and anti-S (16% vs. 99% ). Conclusion The anti-human globulin microcolumn agglutination method outperforms the traditional saline medium test tube method in detecting most unexpected antibodies, offering advantages in automation and ease of use. However, the saline test tube method shows higher sensitivity for certain antibodies (e.g., anti-M and anti-P ₁), though the clinical significance of these antibodies remains unclear and warrants further investigation.

Objective This survey aims to comprehensively and systematically analyze the positive rate of unexpected red cell antibodies and the distribution characteristics of specific antibodies in the Chinese population. This study aims to provide data support for screening unexpected antibodies and for determining the spectrum of cell antigen composition in China. Methods Research literature on unexpected antibodies in hospitalized patients and blood donors across 31 provinces and municipalities in China was searched in PubMed, CNKI, Wanfang Data, and other authoritative databases from 1981 to December 2023. The literature was screened according to inclusion and exclusion criteria, data extraction was performed, and a quality assessment was conducted. Results The positive rate of unexpected red cell antibodies in hospitalized patients was 0.47%. The rate in blood donors was 0.10%. The rate in hospitalized mothers was 0.71%. The rate in blood transfusion patients was 1.22%, and the rate in pregnant women was 0.91%. The positive rate in blood transfusion/pregnancy was 1.15%. The proportion of specific antibodies in hospitalized patients is in the following order: Rh>MNS>Lewis>Kidd>Duffy>Xg>ABO subtype>I>Diego>P>Kell>Lutheran>H; the proportion of specific antibodies in blood donors is in the following order: MNS>Rh>Lewis>P>ABO subtype>I>Kell>Kidd>Diego>Duffy>Lutheran>H; the proportion of specific antibodies in pregnant and postpartum women is in the following order: Rh>MNS>Lewis>Kidd>P>H>Duffy>I>Diego. The composition proportion of specific antibodies in hospitalized patients is in the following order: anti-E>anti-M>anti-D>anti-Ec>anti-Le ^a>anti-C>anti-c>anti-Jk ^a>anti-Ce>anti-Le ^b, the composition proportion of specific antibodies in blood donors is in the following order: anti-M>anti-E>anti-P1>anti-D>anti-Le ^a>anti-Le ^b>anti-C>anti-N>anti-I>anti-A1; the composition proportion of specific antibodies in pregnant and postpartum women is in the following order: anti-E>anti-M>anti-D>anti-C>anti-Le ^a>anti-Ec> anti-EC>anti-P1. Conclusion The positive rate of unexpected antibodies in hospitalized patients in China is significantly higher than that in blood donors, and the distribution characteristics of specific antibodies vary among different populations and regions.

Objective Using PacBio third-generation sequencing technology to determine the haplotype genotypes of 17 blood samples exhibiting mixed vision in ABO blood group typing, with the aim of accurately identifying the ABO blood types. Methods The ABO phenotype was identified by immunoserological method. The ABO genotype was identified by PacBio Third-Generation sequencing technology. Results Seventeen specimens exhibited subtype characteristics in the immunological serology tests. The results of third-generation gene sequencing technology showed that nine of them were subtypes, including five cases of A1Bweak, two cases of cisAB, one case of Bweak, and one case of B(A). The remaining eight cases were non-subtypes, comprising six cases of A1B, one case of A1, and one case of B. Conclusion By combining serological tests with gene sequencing technology to determine the genotype, we can accurately identify blood types and improve the safety of clinical blood transfusions.

Objective To establish a detection process for drug-induced immune thrombocytopenia (DITP) caused by piperacillin-tazobactam sodium, and to provide timely diagnostic criteria for clinical diagnosis of DITP. Methods Platelet antibody screening was conducted using the solid-phase agglutination method. The solid-phase agglutination method was employed in the detection system to test for piperacillin-tazobactam sodium and omeprazole dependent platelet antibodies. In vitro red blood cell sensitization was performed using the anti-human globulin method to detect drug antibodies against piperacillin-tazobactam sodium on red blood cells. The patients were followed up at 1, 2, 5, and 8 days post drug withdrawal to investigate the potency of piperacillin-tazobactam sodium-dependent platelet drug antibodies and observe trends in platelet counts. Results A patient who received piperacillin-tazobactam sodium for 13 days experienced a significant decrease in platelet count and developed bleeding symptoms, which were attributed to the presence of piperacillin-tazobactam sodium-dependent platelet drug antibodies. Conclusion The solid-phase agglutination method incorporating piperacillin-tazobactam sodium can be utilized as a rapid diagnostic tool for detecting drug-dependent platelet antibodies.

Objective To study the serological changes, laboratory detection methods, and transfusion strategies for patients with positive anti-E unexpected antibodies after umbilical cord blood hematopoietic stem cell transplantation with E-positive antigens. Methods ABO and Rh blood typing and unexpected antibody screening tests were performed using conventional serological methods. Unexpected antibody identification was conducted using PEG enhancement technology and acid elution test. Cell population detection was carried out using flow cytometry to analyze the patterns of blood group antigen conversion and antibody resolution. Results The patient had pretransplant blood type AB, Rh type CCDee, with anti-E unexpected antibodies. Unrelated cord blood HSC donor was type B, Rh classification was ccDEE, related hemicompatible peripheral blood HSC donor was type AB, and Rh classification was CcDEe. The patient was in blood group transition and the unexpected antibody screening result was negative, but IgG anti-E antibody was detected by PEG enhancement test and erythrocyte acid release test. Conclusion For patients with similar antibodies before transplantation, PEG enhanced anti-human globulin test is recommended as a supplement to routine serological tests, monitor the changes of alloantibody levels, prevent hemolytic reaction and avoid red cell transfusion refractoriness.

Blood collection and supply institutions, as critical public health entities for collecting and supplying l blood products, face occupational exposure risks to blood-borne pathogens during donor recruitment, physical examinations, blood collection, component preparation, and laboratory testing. This study focuses on the establishment and improvement of IPC mechanism by investigating the current status of infection prevention and control (IPC) management in these institutions, analyzing existing problems and vulnerabilities, drawing on healthcare facilities management models and experience. It has a positive role in standardizing and enhancing IPC measures in blood collection and supply institutions, aim to safeguard the safety of donors, staff and blood products.

Objective To observe the clinical efficacy of plasma exchange in desensitization treatment of DSA (donor-specific antibody) positive patients undergoing hematopoietic stem cell transplantation (HSCT). Methods A retrospective analysis was carried out of 30 DSA positive patients desensitized with plasma exchange and combined with anti-B cell therapy in our hospital from July 2021 to July 2023. We primarily investigated the changes in the average fluorescence intensity of DSA before and after plasma exchange therapy, its impact on the incidence of cell implantation during transplantation and GVHD (graft-versus-host disease) after transplantation, and the adverse reactions during plasma exchange therapy. Results Totally 64 plasma exchanges were performed on 30 patients, with 24 mild adverse reactions including hypocalcemia and allergies. These reactions were relieved after treatment and did not didrupt the plasma exchange process. The average fluorescence intensity of DSA before and after plasma exchange was 7 182.9±5 535.3 and 2 311.8±2 835.9, respectively ( P<0.001). Among the 30 patients, 25 underwent allo-HSCT (umbilical cord blood transplantation in 19 and Haplo HSCT in 6), with 23 (92%) achieving hematopoietic reconstruction. The median engraftment times were 14 (9~60) days for neutrophils and and 31 (10~64) days for platelets. Two patients underwent secondary transplantation due to failed engraftment. Five patients were not transplanted or their data was deleted. The cumulative incidence of Ⅱ~Ⅳ aGVHD within 30 days after transplantation in 23 patients was 41%. Conclusion Plasma exchange combined with anti B cell therapy is an effective desensitization therapy for DSA positive patients subjected to hematopoietic stem cell transplantation.

Logic is a fundamental element of academic papers, significantly influencing their quality and the likelihood of successful submission. Present throughout every section of a paper, logic plays a crucial role—from clarifying concepts and constructing rigorous arguments to formulating valid conclusions. This article explores the essence of logical thinking and incorporates practical case studies to analyze key aspects such as concept clarity, argument rigor, scientific reasoning, and presentation standardization. By combining theoretical discussion with case analysis, the article highlights the pivotal role of logical rigor in determining the overall quality of academic papers. Enhancing logical reasoning skills, standardizing the argumentation process, ensuring consistency between premises and conclusions, and adopting concise and clear writing based on logical principles are essential strategies for improving a paper's credibility and scientific impact.

Objective To analyze the diagnostic value of long noncoding RNAs (lncRNAs) in platelets in early screening of colon cancer (CC). Methods The GSE68086 and GSE183635 datasets, which contain platelet lncRNAs data from CC patients and healthy controls, were analyzed using the “limma” package in R. The intersection of the results was utilized to identify differentially expressed lncRNAs (DElncRNAs). The Wilcoxon rank sum test in R language was used to analyze the differential expression of DElncRNAs in CC tissues and normal control tissues. Quantitative real-time PCR (qRT-PCR) was used to detect the expression levels of platelet LINC00926 in 60 healthy controls and 66 CC patients. The receiver operating characteristic (ROC) was used to evaluate diagnostic performance. Results The differential analysis of GSE68086 dataset identified 341 DElncRNAs, and the GSE183635 dataset identified 21 DElncRNAs. The key DElncRNA LINC00926 was obtained from the intersection. R language Wilcoxon rank sum test showed that the expression level of platelet LINC00926 in CC tissues was lower than that in normal colon tissues ( P<0.05). qRT-PCR confirmed that down-regulation of platelet LINC00926 in CC patients and early-stage CC patients (both P<0.001). The area under the curve (AUC) of platelet LINC00926 for CC diagnosis was 0.781, with a specificity of 80.0% and sensitivity of 74.2%. AUC for early-stage CC diagnosis was 0.761, with a specificity of 78.3% and sensitivity of 70.8%. The combined diagnostic model of platelet LINC00926 and carcinoembryonic antigen (CEA) had an AUC of 0.864, a specificity of 91.7% and sensitivity of 69.7%. The AUC for early-stage CC diagnosis was 0.851, with a specificity of 75.0% and sensitivity of 85.4% ( P<0.05). In both CC and early-stage CC, the detection of AUC of platelet LINC00926 combined with CEA was superior to that of single detection (z =-2.619, 2.388, respectively, both P<0.05). Conclusion The LINC00926 expression in platelets of CC patients was down-regulated. It suggests that platelet LINC00926 may enhance the diagnostic value of early screening for colon cancer.

Dengue fever caused by mosquito-borne viruses is spreading rapidly around the world, mainly in tropical, subtropical countries. In recent years, dengue fever has expanded epidemic trend in our country, now there are also studies showing that dengue fever can be transmitted through blood transfusion, which not only poses a serious threat to public health, but also poses a potential risk to the safety of blood transfusion. This article reviews the biological characteristics, epidemiology, transmission routes, clinical symptoms, detection methods, blood transfusion safety status, blood transfusion prevention, control strategies of dengue fever.

Objective To investigate the clinical significance of third-generation gene sequencing (TGS) in detecting Kidd blood group antigen in weakly expressed samples. Methods Samples of patients in Xinjiang Autonomous Region People's Hospital were collected, Jka and Jkb antigens were detected by serological methods, and 9 cases of weakly expressed samples of Kidd blood group genes were subjected to full-length single-molecule real-time sequencing technology (third-generation high-throughput sequencing) to obtain their gene polymorphisms and statistically analyzed. Results The main mutation sites of the Kidd blood group gene were detected in this study: c.588A>G, c.838G>A, and c.130G>A. In addition, 5 samples were found to have new gene mutation types, with 2 being homozygous and 3 heterozygous. The new mutation gene types were: c.499A>G, c.588A>G, and c.838G>A, which are mainly seen in the Jk(b+) phenotype. The allele name for the new mutation is JK*02.NEW. In 9 samples, 7 of the genetic test results were different from the serological results, and all of them had ISBT-recorded or unrecorded gene mutation sites. At the same time, the specificity of the mutation gene sites and the corresponding amino acid changes were summarized and analyzed. Conclusion The present study investigated the mutation, splicing, folding, and amino acid sequence of the Kidd gene in the Xinjiang population. This research lays a solid foundation for gaining further insights into the specificity of blood groups in this region and provides a fundamental basis for future construction of three-dimensional protein models.

Objective To analyze the serological and molecular biological characteristics of Bweak subtype probands and their families, and to explore the molecular mechanism and genetic characteristics of Bw27 variant. Methods Serological methods were used to detect ABO blood group antigens and antibodies in the proband and family members. Further serological detection was conducted by absorption and elution. Fluorescence PCR was employed for genotyping, and the 6th and 7th exons of the ABO gene were amplified and sequenced. Results The proband's ABO serological test showed inconsistent in p forward and reverse typing, and the absorption and elution test detected weak B antigen on the proband's red blood cells, with a serological phenotype similar to Bel. The genotyping result was B/O1, and gene sequencing revealed a c.905A>G mutation in the 7th exon of the ABO gene, with a genotype of ABO*BW.27/ABO*O.01.01. Pedigree testing results showed that the proband's mother carried the ABO*BW.27 allele, consistent with familial genetic characteristics. Conclusion The c.905A>G mutation in the 7th exon of the ABO gene leads to the substitution of aspartic acid at position 302 with glycine, resulting in weak expression of B antigen, which is a characteristic mutations of ABO*BW.27 that can be distinguished from Bel by gene sequencing. A single nucleotide point mutations can cause specific changes in glycosyltransferase and can be inherited to produce specific serological phenotypes in offspring. Blood types should be comprehensively determined based on serological results with genotyping and DNA sequencing results.

Objective This retrospective study is to compare the safety, efficacy and short-term outcomes between blinatumomab and anti-CD19 CAR-T cell therapy in B-ALL patients treated at our institution. Methods The cohort included 21 patients treated with blinatumomab (2021—2023) and 80 patients treated with anti-CD19 CAR-T cells (2016—2020). Results In blinatumomab group, 52.4% (11/21) of patients experienced cytokine release syndrome (CRS), with no severe CRS or neurotoxicity reported, and 90.5% achieved MRD-negative complete remission (CR). In contrast, 95.5% (64/67) of patients in the CAR-T group experienced CRS, with 38.9% (26/67) classified as severe cases, and 86.7% achieved MRD-negative CR. Based on the results of the subgroup analysis, blinatumomab was associated with milder CRS compared to CAR-T therapy, regardless of pre-treatment tumor burden or relapse status ( P<0.05). The efficacy between the two groups was comparable. The median progression-free survival (PFS) and overall survival (OS) were not reached in the blinatumomab group, with 12-month PFS and OS rates of 70.7% and 88.1%, respectively. In the CAR-T group, the median PFS and OS were 12.3 months and 19.0 months, with 12-month rates of 52.0% and 62.4%. Patients who underwent umbilical cord blood transplantation (UCBT) post-treatment had significantly improved PFS ( P=0.010 for blinatumomab, P<0.001 for CAR-T). Conclusion In patients with B-ALL across varying tumor burdens and relapse counts, the efficacy of blinatumomab was comparable to that of CD19 CAR-T cell therapy, with a notably lower incidence of cytokine release syndrome (CRS). Post-treatment UCBT significantly enhanced patient survival. However, due to limited sample size and follow-up duration for the blinatumomab group, further research is needed to confirm the long-term efficacy.

Objective The changes in the main functional components of human plasma-derived factor Ⅷ (FⅧ)products in China in recent years were analyzed to provide a reference for the development of plasma protein products, improvement of the preparation processes of plasma-derived FⅧ, and their clinical application. Methods Nine commercially available FⅧ products (A-I) from Chinese manufacturers were dissolved according to the instructions. Protein concentration was measured using the BCA method, FⅧ activity was determined by a one-stage method, VWF activity and VWF antigen were assessed by immunoturbidimetry. The specific activity of FⅧ, the ratio of VWF:Ac/FⅧ:C and VWF:Ac/VWF:Ag were calculated and compared with products produced between 2015 and 2017 (a-g). The changes of main functional components of FⅧ were analyzed. Results The average FⅧ activity of product A-I was (20.70±2.06) IU/mL, showing no significant difference compared to previous products. The mean specific activity was (36.53±19.20) IU/mg, significantly higher than before ( P<0.01). The average VWF:Ac/FⅧ:C was 0.43±0.12, indicating a significant decrease compared to previous products ( P<0.000 1). The mean VWF:Ac/VWF:Ag was 0.70±0.16, also significantly lower than before ( P<0.01). Compared with foreign product Wilate®, Chinese products exhibited significantly lower FⅧ specific activity ( P<0.05) and VWF activity ( P<0.000 1). Conclusion Currently, the purity of human plasma-derived FⅧ products in China exceeds the requirements of the Chinese Pharmacopoeia (2020 edition), and has significantly improved compared to the past. However, the quality of VWF activity has decreased making these products less suitable for treating von Willebrand disease (VWD). Compared with foreign products, human plasma-derived FⅧ products in China have a greater improvement in both FⅧ purity and VWF activity.

Objective To assess the miss detection rate (MDR) and frequency of the D variant among RhD negativeblood donors in Taiyuan. Methods From January 2013 to December 2021, 6 287 RhD negativeblood samples, initially screened, were collected. These samples were further confirmed using the tube antiglobulin test or microcolumn gel card method. RhD genotyping was done on the 17 specimens which showed discrepancies with previous testresults or the manufacturer's specifications for the primary screening reagent. By analyzing the number of D variant donors, blood donations and missed detections, the theoretical MDR and frequency of D variant were calculated in the RhD negativeblood samples from the primary screening. Results Between January 2013 and December 2021, the detection rate of D variant in the 6 287 RhD negative samples (including repeat donors) by preliminary screening was 5.36%（337/6 287）. Statistical analysis of 59 D variant blood donors who donated more than once revealed that theoretically, 5.37% of D variants were missed. Considering the MDR, the theoretical frequency of D variant in the RhD negative population from the preliminary screening was 7.68%. Conclusion Some D variant blood donors were missed in the conventional test. The theoretical MDR and frequency of D variant in the RhD negative samples by primary screening align more closely with the actual situation.

Objective To investigate the present situation of Alanine Aminotransferase (ALT) testing in blood collection and supply institutions across China and offer insights for decision-making by management authorities. Methods We conducted a literature review, and developed a survey questionnaire based on evidence-based practices. Electronic questionnaires were distributed to 51 blood collection and supply institutions across the country to gather information on ALT testing practices from January 2023 to September 2024. The collected data were systematically analyzed. Results All domestic blood collection and supply institutions have implemented the ALT screening project before blood donation, with a 100% coverage rate of ALT screening before blood donation. The main method for ALT testing before blood donation is dry chemical method (66.62%), while the main method for ALT testing after blood donation is rate method (82.35%). There are differences in the repeatability of the test results. Screening periods of unqualified ALT tests before blood donation varied, ranging from 1 day to 180 days, with a median period of 7 days. The voluntary recall rate after the the shielding period expired was low (39.22%). A significant number of blood donors were eliminated due to failed ALT tests, with nearly 225 000 individuals rejected across 51 institutions during the survey period. Conclusion The current ALT testing criteria exclude a large number of potential blood donors, resulting in unnecessary waste nationwide. Clinical research based on China's specific situation is needed to to evaluate the necessity of the ALT test, consider adjusting the ALT reference range, and optimize blood donation qualifications. Such measures could improve donor participation, reduce blood loss, and ensure the safety and stability of the national blood supply.