Missense mutations in PIEZO1, which encodes the Piezo1 mechanosensor protein, define Er red blood cell antigens.

Despite the identification of the high-incidence red cell antigen Era nearly 40 years ago, the molecular background of this antigen, together with the other 2 members of the Er blood group collection, has yet to be elucidated. Whole exome and Sanger sequencing of individuals with serologically defined Er alloantibodies identified several missense mutations within the PIEZO1 gene, encoding amino acid substitutions within the extracellular domain of the Piezo1 mechanosensor ion channel. Confirmation of Piezo1 as the carrier molecule for the Er blood group antigens was demonstrated using immunoprecipitation, CRISPR/Cas9-mediated gene knockout, and expression studies in an erythroblast cell line. We report the molecular bases of 5 Er blood group antigens: the recognized Era, Erb, and Er3 antigens and 2 novel high-incidence Er antigens, described here as Er4 and Er5, establishing a new blood group system. Anti-Er4 and anti-Er5 are implicated in severe hemolytic disease of the fetus and newborn. Demonstration of Piezo1, present at just a few hundred copies on the surface of the red blood cell, as the site of a new blood group system highlights the potential antigenicity of even low-abundance membrane proteins and contributes to our understanding of the in vivo characteristics of this important and widely studied protein in transfusion biology and beyond.

Estimating the risks of prehospital transfusion of D-positive whole blood to trauma patients who are bleeding in England.

BACKGROUND AND OBJECTIVES: D-negative red cells are transfused to D-negative females of childbearing potential (CBP) to prevent haemolytic disease of the foetus and newborn (HDFN). Transfusion of low-titre group O whole blood (LTOWB) prehospital is gaining interest, to potentially improve clinical outcomes and for logistical benefits compared to standard of care. Enhanced donor selection requirements and reduced shelf-life of LTOWB compared to red cells makes the provision of this product challenging. MATERIALS AND METHODS: A universal policy change to the use of D-positive LTOWB across England was modelled in terms of risk of three specific harms occurring: risk of haemolytic transfusion reaction now or in the future, and the risk of HDFN in future pregnancies for all recipients or D-negative females of CBP. RESULTS: The risk of any of the three harms occurring for all recipients was 1:14 × 103 transfusions (credibility interval [CI] 56 × 102 -42 × 103 ) while for females of CBP it was 1:520 transfusions (CI 250-1700). The latter was dominated by HDFN risk, which would be expected to occur once every 5.7 years (CI 2.6-22.5). We estimated that a survival benefit of ≥1% using LTOWB would result in more life-years gained than lost if D-positive units were transfused exclusively. These risks would be lower, if D-positive blood were only transfused when D-negative units are unavailable. CONCLUSION: These data suggest that the risk of transfusing RhD-positive blood is low in the prehospital setting and must be balanced against its potential benefits.

Modelling the outcomes of different red blood cell transfusion strategies for the treatment of traumatic haemorrhage in the prehospital setting in the United Kingdom.

BACKGROUND AND OBJECTIVES: The limited supply and increasing demand of group O RhD-negative red blood cells (RBCs) have resulted in other transfusion strategies being explored by blood services that carry potential risks but may still provide an overall benefit to patients. Our aim was to analyse the potential economic benefits of prehospital transfusion (PHT) against no PHT. MATERIALS AND METHODS: The impact of three PHT strategies (RhD-negative RBC, RhD-positive RBC and no transfusion) on quality-adjusted-life-years (QALYs) of all United Kingdom trauma patients in a given year and the subset of patients considered most at risk (RhD-negative females <50 years old), was modelled. RESULTS: For the entire cohort and the subset of patients, transfusing RhD-negative RBCs generated the most QALYs (141,899 and 2977, respectively), followed by the RhD-positive RBCs (141,879.8 and 2958.8 respectively), and no prehospital RBCs (119,285 and 2503 respectively). The QALY difference between RhD-negative and RhD-positive policies was smaller (19.2, both cohorts) than RhD-positive and no RBCs policies in QALYs term (22,600 all cohort, 470 for a subset), indicating that harms from transfusing RhD-positive RBCs are lower than harms associated with no RBC transfusion. A survival increase from PHT of 0.02% (entire cohort) and 0.7% (subset cohort) would still make the RhD-positive strategy better in QALYs terms than no PHT. CONCLUSION: While the use of RhD-positive RBCs carries risks, the benefits measured in QALYs are higher than if no PHT are administered, even for women of childbearing potential. Group O RhD-positive RBCs could be considered when there is a national shortage of RhD-negative RBCs.

Lactate, a product of glycolytic metabolism, inhibits histone deacetylase activity and promotes changes in gene expression.

Chemical inhibitors of histone deacetylase (HDAC) activity are used as experimental tools to induce histone hyperacetylation and deregulate gene transcription, but it is not known whether the inhibition of HDACs plays any part in the normal physiological regulation of transcription. Using both in vitro and in vivo assays, we show that lactate, which accumulates when glycolysis exceeds the cell's aerobic metabolic capacity, is an endogenous HDAC inhibitor, deregulating transcription in an HDAC-dependent manner. Lactate is a relatively weak inhibitor (IC(50) 40 mM) compared to the established inhibitors trichostatin A and butyrate, but the genes deregulated overlap significantly with those affected by low concentrations of the more potent inhibitors. HDAC inhibition causes significant up and downregulation of genes, but genes that are associated with HDAC proteins are more likely to be upregulated and less likely to be downregulated than would be expected. Our results suggest that the primary effect of HDAC inhibition by endogenous short-chain fatty acids like lactate is to promote gene expression at genes associated with HDAC proteins. Therefore, we propose that lactate may be an important transcriptional regulator, linking the metabolic state of the cell to gene transcription.

Quality in practice: implementation of hospital guidelines for patient identification in Malawi.

QUALITY PROBLEM OR ISSUE: Patient identification in a teaching hospital in Malawi. Initial assessment 34% of hospital staff recalled a misidentification event in the preceding year; less than 10% of staff described the use of unique patient identifiers other than name when taking blood samples and 98% of laboratory requests included no identifiers other than name. CHOICE OF SOLUTION: Hospital identification guidelines based on WHO guidelines to introduce identification wristbands; encourage routine use of an identifier in addition to name on laboratory requests and improve bedside identification procedures. IMPLEMENTATION: Provision of wristbands, educational materials, workshops and distribution of written materials to promote the new guidelines with regular monitoring. EVALUATION: At 5 months 65% of in-patients wore wristbands compliant with WHO identification guidelines and 55% of cross-match forms used a second identifier. Only 10% of non-cross-match forms had a second identifier. The use of recommended bedside identification procedures was rarely observed. Guidelines were welcomed by both staff and patients; identification wristbands were found useful in difficult identification situations. Lack of time, staffing and unimportance of procedures were given as reasons for not following guidelines. LESSONS LEARNED: Identification procedures can be rapidly introduced in a developing world context in a manner acceptable to patients and staff. Tangible tools such as wristbands appeared easier to implement than changing practice by education. Recommendations for wider implementation include increased engagement of patients in addition to healthcare and management staff; use of rejection criteria for inadequately labeled samples; generating further evidence about the prevalence, type and consequences of patient misidentification events.

Large red cell-derived membrane particles are major contributors to hypercoagulability in sickle cell disease.

Sickle cell disease (SCD) is one of the most common inherited single gene disorders. Polymerisation of sickle hemoglobin results in erythrocytes that are inflexible and adherent, leading to coagulation, vascular and cellular activation and resultant blood vessel blockage. Previous studies have observed elevated numbers of red cell-derived particles (RCDP), also denoted extracellular vesicles, in SCD plasma. Here, imaging flow cytometry was used to quantify all RCDP in SCD plasma. A more heterogenous population of RCDP was observed than previously reported. Significantly, large right side-out red cell macrovesicles (MaV), 7 µm in diameter, were identified. Most RCDP were right side-out but a minor population of inside-out vesicles was also present. Electron micrographs confirmed the heterogenous nature of the RCDP detected. All MaV are decorated with prothrombotic phosphatidylserine (PS) and their removal from plasma lengthened clotting times by more than three-fold. Removal of all right side-out RCDP from SCD patient plasma samples resulted in a seven-fold increase in clotting time. These results indicate that MaV comprise a large area of prothrombotic membrane and are thus major contributors to hypercoagulation in SCD. Consequently, controlled removal of MaV and PS exposed RCDP from plasma could provide a novel therapy for managing this disease.

DNA methylation in mouse embryonic stem cells and development.

Mammalian development is associated with considerable changes in global DNA methylation levels at times of genomic reprogramming. Normal DNA methylation is essential for development but, despite considerable advances in our understanding of the DNA methyltransferases, the reason that development fails when DNA methylation is deficient remains unclear. Furthermore, although much is known about the enzymes that cause DNA methylation, comparatively little is known about the mechanisms or significance of active demethylation in early development. In this review, we discuss the roles of the various DNA methyltransferases and their likely functions in development.

A Pilot Study Assessing the Impact of 3-D Printed Models of Aortic Aneurysms on Management Decisions in EVAR Planning.

INTRODUCTION: Endovascular repair of aortic aneurysms with difficult anatomy is challenging. There is no consensus for planning such procedures. METHODS: Six cases of aortic aneurysms with challenging anatomical features, such as short, angulated, and conical necks and tortuous iliacs were harvested. The computed tomography (CT) scans were anonymized. Lifesize 3-dimensional (3-D) printed models were created of the lumen. Endovascular operators were asked to review the CT angiography (CTA), make a management plan, and give an indication of their confidence. They were then presented with the equivalent model and asked to review their decision. Their attitudes to such models were briefly surveyed. RESULTS: A total of 28 endovascular operators reviewed 144 cases. After review of the physical model, the management plan changed in 29 (20.1%) of 144 cases. Initial plan after CTA review was endovascular 73.6%, open repair 22.9%, and second opinion 3.5%. After model review, this became endovascular 67.4%, open repair 19.4%, and second opinion 4.8%. Although the general trend was toward more open procedures, off-label techniques reduced from 19.4% to 15.2% following model review. When the management plan did not change, level of confidence did increase in 37 (43.5%) of 85 cases. The majority of operators stated that they would find models useful for planning in some procedures. For 1 case, the change in the percentage of participants being sure in the management plan was statistically significant (P = .031). CONCLUSION: The 3-D printed models may be potentially useful in planning cases with EVAR. It is a paradigm that warrants further investigation.

Is cytotoxic chemotherapy for lymphoma currently feasible for patients in Malawi? A debate.

There is currently no systematic provision for chemotherapy of adult patients with cancer in Malawi. Is the introduction of such a service now feasible in Malawi, and should an individual patient with potentially treatable disease be given chemotherapy in the absence of such a service? The technical, economic and moral issues are discussed here in the form of a debate.