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Background and Objectives: In 1993, a quarantine storage of 6 months was introduced for plasma for transfusion and was reduced to 4 months in 2003, owing to the improvements of screening assays used in German blood establishments. The presented survey analyses the value of quarantine storage under the current screening conditions. Materials and Methods: From 2015 to 2019, we collected data on the total amount of released quarantine plasma as well as on the number of quarantine plasma not released due to a reactive screening test of a follow-up donation. Results: Responding establishments covered 84% of plasma units released within the sampled period. In 3,583,913 (99.98%) of the total 3,584,664 test pairs, all screening assays revealed a negative result, leading to plasma release from quarantine storage. In 442 out of the residual 751 cases, confirmed positive results for human immunodeficiency virus (24), hepatitis C virus (22), or hepatitis B virus (396) were obtained in the follow-up donations. Of them, 372 revealed negative ID-NAT results in their retain samples confirmed by using highly sensitive individual donor nucleic acid amplification technology. In 70 cases, no testing of retain samples was performed as plasma was released for fractionation. The maximum theoretical risk for an undetected human immunodeficiency virus, hepatitis C or B virus infection was less than 0.0001%. Conclusion: No positive donation were found under the current screening regime and the quarantine storage during the 5-year survey period. In view of the current type and sensitivity of screening tests in German blood establishments, the results allow a reassessment of the value of quarantine storage of plasma regarding duration and release modalities. Due to the more sensitive donor screening, shorter quarantine periods as well as dispensing quarantine storage can be discussed. A reduction in the safety standard of plasma transfusions need not be feared, and the availability of plasma for transfusions could be facilitated.
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Background and Objectives: A sufficient supply of safe, high-quality blood components for transfusion is essential to the healthcare system in Germany. The requirements for the current reporting system are laid down in the German Transfusion Act. The present work elaborates on the advantages and limitations of the current reporting system and investigates the feasibility of a pilot project that collects specific data on blood supply based on weekly reports. Materials and Methods: Selected data on blood collection and supply from 2009 to 2021 derived from the §21 German Transfusion Act database were examined. In addition, a pilot study over a period of 12 months was conducted on a voluntary basis. The number of red blood cell (RBC) concentrates was documented and stock availability was calculated weekly. Results: From 2009 to 2021, the annual number of RBC concentrates decreased from 4.68 to 3.43 million, the per capita distribution decreased from 58 to 41 RBC concentrates per 1,000 inhabitants. These figures did not change significantly during the COVID-19 pandemic. The data of the 1-year pilot project represented 77% of the released RBC concentrates in Germany. Percentage share of O RhD positive RBC concentrates fluctuated between 35% and 22% and for O RhD negative concentrates between 17% and 5%. The availability of O RhD positive RBC concentrate stocks varied between 2.1 and 7.6 days. Conclusion: The data presented shows a decrease in annual RBC concentrate sales over an 11-year period and no further change over the past 2 years. A weekly monitoring of blood components detects acute problems in RBC provision and supply. Close monitoring seems helpful but should be combined with a nationwide supply strategy.
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BACKGROUND: Platelet concentrates play an important role in transfusion medicine. Their short lifespan and lack of robustness require efforts to ensure adequate product quality. In this study, we compared the in vitro quality of the main concentrate types, pooled platelet concentrate (PPC) from whole blood donations, and platelet concentrate from single-donor apheresis (APC). METHODS: Twenty PPCs and 20 APCs prepared in plasma were analyzed on days 2, 4, and 7 of storage. Variables related to metabolism, degranulation, platelet aggregation, P-selectin expression, and annexin V binding were analyzed. Morphology was assessed by transmission electron microscopy of ultrathin sections. A microfluidic device was applied to test the effects of shear stress on platelet function. RESULTS: The metabolic parameters indicated stable storage conditions throughout the 7-day period. The resting discoid form was the prevailing morphology on days 2 and 4 in the PPCs and APCs. Chemokine release and receptor shedding of soluble P-selectin and soluble CD40L equally increased in PPCs and APCs. Aggregation responses to ADP and collagen were heterogeneous, with marked losses in collagen responsiveness on day 4 in individual concentrates. Baseline expression of P-selectin in PPCs and APCs was low, and inducibility of P-selectin was well preserved until day 4. Under shear stress, equal adhesiveness and stability were found with platelets from PPCs and APCs. CONCLUSIONS: Platelets from PPCs and APCs showed similar in vitro function and stability parameters. However, platelet concentrates presented a high variability and individual concentrates an impaired functional capability. Identifying the factors contributing to this would help increase product reliability.
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The proteorhodopsin (PR) family found in bacteria near the ocean's surface consists of hundreds of PR variants color-tuned to their environment. PR contains a highly conserved single histidine at position 75, which is not found in most other retinal proteins. Using (13)C and (15)N MAS NMR, we were able to prove for green PR that His75 forms a pH-dependent H-bond with the primary proton acceptor Asp97, which explains its unusually high pK(a). The functional role of His75 has been studied using site-directed mutagenesis and time-resolved optical spectroscopy: Ultrafast vis-pump/vis-probe experiments on PR(H75N) showed that the primary reaction dynamics is retained, while flash photolysis experiments revealed an accelerated photocycle. Our data show the formation of a pH-dependent His-Asp cluster which might be typical for eubacterial retinal proteins. Despite its stabilizing function, His75 was found to slow the photocycle in wild-type PR. This means that PR was not optimized by evolution for fast proton transfer, which raises questions about its true function in vivo.