Red blood cells function as reservoirs of tumor DNA

Novel screening techniques for early detection of lung cancer are urgently needed. Profiling circulating tumor cell-free DNA (ctDNA) has emerged as a promising tool for biopsy-free tumor genotyping. However, both the scarcity and short half-life of ctDNA substantially limit the sensitivity and clinical utility of ctDNA detection methodologies. Our discovery that red blood cells (RBCs) sequester mitochondrial DNA opens a new avenue for detecting circulating nucleic acids, as RBCs represent an unrecognized reservoir of circulating nucleic acid. Here, we show that RBCs acquire tumor DNA following coculture with lung cancer cell lines harboring Kirsten rat sarcoma viral oncogene homolog (KRAS) and epidermal growth factor receptor (EGFR) mutations. RBC-bound tumor DNA is detectable in patients with early-stage non-small cell lung cancer (NSCLC) but not in healthy controls by qPCR. Our results collectively uncover a previously unrecognized yet easily accessible reservoir of tumor DNA, offering a promising foundation for future RBC-based tumor diagnostics.NEW & NOTEWORTHY We present a novel method for lung cancer detection by revealing RBCs as a reservoir for tumor DNA, overcoming the limitations of current circulating tumor ctDNA methodologies. By demonstrating that RBCs can capture tumor DNA, including critical mutations found in lung cancer, we provide a promising, biopsy-free avenue for early cancer diagnostics. This discovery opens up exciting possibilities for developing RBC-based diagnostic tools, significantly enhancing the sensitivity and clinical utility of noninvasive cancer detection.

Continuation of chronic antiplatelet therapy is not associated with increased need for transfusions: a cohort study in critically ill septic patients

BACKGROUND

The decision to maintain or halt antiplatelet medication in septic patients admitted to intensive care units presents a clinical dilemma. This is due to the necessity to balance the benefits of preventing thromboembolic incidents and leveraging anti-inflammatory properties against the increased risk of bleeding.

METHODS

This study involves a secondary analysis of data from a prospective cohort study focusing on patients diagnosed with severe sepsis or septic shock. We evaluated the outcomes of 203 patients, examining mortality rates and the requirement for transfusion. The cohort was divided into two groups: those whose antiplatelet therapy was sustained (n = 114) and those in whom it was discontinued (n = 89). To account for potential biases such as indication for antiplatelet therapy, propensity score matching was employed.

RESULTS

Therapy continuation did not significantly alter transfusion requirements (discontinued vs. continued in matched samples: red blood cell concentrates 51.7% vs. 68.3%, p = 0.09; platelet concentrates 21.7% vs. 18.3%, p = 0.82; fresh frozen plasma concentrates 38.3% vs. 33.3%, p = 0.7). 90-day survival was higher within the continued group (30.0% vs. 70.0%; p < 0.001) and the Log-rank test (7-day survivors; p = 0.001) as well as Cox regression (both matched samples) suggested an association between continuation of antiplatelet therapy < 7 days and survival (HR: 0.24, 95%-CI 0.10 to 0.63, p = 0.004). Sepsis severity expressed by the SOFA score did not differ significantly in matched and unmatched patients (both p > 0.05).

CONCLUSIONS

The findings suggest that continuing antiplatelet therapy in septic patients admitted to intensive care units could be associated with a significant survival benefit without substantially increasing the need for transfusion. These results highlight the importance of a nuanced approach to managing antiplatelet medication in the context of severe sepsis and septic shock.

Gender is Independently Associated With Red Blood Cell and Platelet Transfusion in Patients Undergoing Coronary Artery Bypass Grafting: Data From the Netherlands Heart Registration

OBJECTIVES

The aim of this study was to evaluate the incidence of transfusions, including red blood cells (RBC), platelets, and fresh frozen plasma (FFP) during and after coronary artery bypass grafting (CABG) in the Netherlands. Furthermore, the authors aimed to identify the impact of sex on blood product transfusion.

DESIGN

A retrospective multicenter cohort study. Data were collected from January 2013 to December 2021 from the Netherlands Heart Registration (NHR) database.

SETTING

The NHR receives its data from 16 heart centers in the Netherlands.

PARTICIPANTS

Patients older than 18 years who underwent CABG in the Netherlands.

INTERVENTIONS

Coronary artery bypass grafting with extracorporeal circulation or off-pump coronary artery bypass grafting.

MEASUREMENTS AND MAIN RESULTS

The incidence of blood transfusion, defined as transfusions intraoperatively and during the length of the hospital admission after CABG. In addition, a differentiation was made according to the type of transfusion (packed RBC, platelets, and FFP). In the overall cohort (N = 42,388), the number of patients who received a transfusion of any type was 27.0% (n = 11,428). Women received more often RBC transfusions compared with men (45.4% v 15.6%, respectively, p < 0.001). There was a significant difference between the 2 sexes regarding platelet transfusion (women 10.0% v men 11.1%, p = 0.005) but not in FFP transfusion. Female sex was independently associated with RBC transfusion, using the multivariate logistic regression analysis.

CONCLUSIONS

The incidence of any blood transfusion was 27.0%, and was higher in women than in men. The female sex was independently associated with receiving RBC during and after CABG.

A Simplified Method for Calculating Surface Area of Mammalian Erythrocytes

Knowledge of the geometric quantities of the erythrocyte is useful in several physiological studies, both for zoologists and veterinarians. While the diameter and volume (MCV) are easily obtained from observations of blood smears and complete blood count, respectively, the thickness and surface area are instead much more difficult to measure. The precise description of the erythrocyte geometry is given by the equation of the oval of Cassini, but the formulas deriving from it are very complex, comprising elliptic integrals. In this article, three solids are proposed as models approximating the erythrocyte: sphere, cylinder and a spheroid with concave caps. The volumes and surface areas obtained with these models are compared to those effectively measured. The spheroid with concave caps gives the best approximation and can be used as a simple model to determine the erythrocyte surface area. With this model, a simple method that allows one to estimate the surface area by knowing only the diameter and MCV is proposed.

Assessment of Erythrocyte Osmotic Fragility and Its Determinants, and Comparison of Hematological Indices Among Type 2 Diabetes Mellitus Patients on Follow-Up at Jimma Medical Center, Southwest Ethiopia

Background

Diabetes Mellitus (DM) is one of the most prevalent non-communicable diseases worldwide. Approximately 9.3% of the general population was estimated to have DM globally in 2019. Erythrocyte osmotic fragility (EOF) in hyperglycemic patients is expected to increase and determine the rate of erythrocyte hemolysis.

Purpose

This study aimed to assess erythrocyte osmotic fragility (EOF) and its determinants and to compare hematological indices among T2DM patients on follow-up at the Jimma Medical Center (JMC), Jimma, Southwest Ethiopia.

Methods

A facility-based cross-sectional study involving 124 participants (each 62) of T2DM patients and controls was conducted from October to November 2020 using a structured questionnaire. 5 mL of venous blood was drawn to assess OF, complete blood count, and blood glucose levels. EOF was investigated using a series hypotonic solution of NaCl. The supernatant of the centrifuged sample was transferred to cuvette test tubes, and the hemolysis stage was read on a spectrophotometer. The collected data were coded and entered into Epi-data Version 3.1. The analysis was performed using SPSS Version 23.

Results

Compared with non-diabetic controls, patients with T2DM had significantly increased EOF. FBG >126mg/dl (AOR=7.741, 95% CI: 1.562-38.360), PPBG >200 mg/dl (AOR=7.576, 95% CI: 1.519-37.791), RDW (AOR=4.558, 95% CI: 1.136-18.284) were significantly associated with abnormal EOF. A statistically significant increase in total white blood cells and absolute neutrophil counts (P < 0.001) were observed in T2DM patients. From RBC indices, red blood cell distribution width (RDW) and mean corpuscular volume (MCV) were significantly increased in T2DM patients (P < 0.001).

Conclusion

This study suggests that EOF was greater in patients with T2DM than in non-diabetic controls and was determined by FBG, PPBG, and RDW. The study also demonstrated that hematological index alterations were higher in T2DM subjects than in non-diabetic controls.

Pegylation, a Successful Strategy to Address the Storage and Instability Problems of Blood Products: Review 2011-2021

Conjugation of polyethylene glycol (PEGylation) to blood proteins and cells has emerged as a successful approach to address some of the issues attributed to the storage of blood products, including their short half-life and instability. In this regard, this review study aims to compare the influence of different PEGylation strategies on the quality of several blood products like red blood cells (RBCs), platelets, plasma proteins, i.e., albumin, coagulation factor VIII, and antibodies. The results indicated that conjugating succinimidyl carbonate methoxyPEG (SCmPEG) to platelets could improve blood transfusion safety by preventing these cells from being attached to low-load hidden bacteria in blood products. Moreover, coating of 20 kD succinimidyl valerate (SVA)-mPEG to RBCs was able to extend the half-life and stability of these cells during storage, as well as immune camouflage their surface antigens to prevent alloimmunisation. As regards albumin products, PEGylation improved the albumin stability, especially during sterilization, and there was a relationship between the molecular weight (MW) of PEG molecules and the biological half-life of the conjugate. Although coating antibodies with short-chain PEG molecules could enhance their stabilities, these modified proteins were cleared from the blood faster. Also, branched PEG molecules enhanced the retention and shielding of the fragmented and bispecific antibodies. Overall, the results of this literature review indicate that PEGylation can be considered a useful tool for enhancing the stability and storage of blood components.

Not as "D"eadly as once thought - the risk of D-alloimmunization and hemolytic disease of the fetus and newborn following RhD-positive transfusion in trauma

The use of blood products to resuscitate injured and massively bleeding patients in the prehospital and early in-hospital phase of the resuscitation is increasing. Using group O red blood cells (RBC) and low titer group O whole blood (LTOWB) avoids an immediate hemolytic reaction from recipient's naturally occurring anti-A and - B, but choosing the RhD type for these products is more nuanced and requires the balancing of product availability and survival benefit against the risk of D-alloimmunization, especially in females of childbearing potential (FCP) due to the possible future occurrence of hemolytic disease of the fetus and newborn (HDFN). Recent models have estimated the risk of fetal/neonatal death from HDFN resulting from D-alloimmunization of an FCP during her trauma resuscitation at between 0-6.5% depending on her age at the time of the transfusion and other societal factors including trauma mortality, her age when she becomes pregnant, frequency of different RHD genotypes in the population, and the probability that the woman will have children with different fathers; this is counterbalanced by an approximately 24% risk of death from hemorrhagic shock. This review will discuss the different models of HDFN outcomes following RhD-positive transfusion as well as the results of recent surveys where the public was asked about their preferences for urgent transfusion in light of the risks of fetal/neonatal adverse events.

Lysosomal-targeted doxorubicin delivery using RBC-derived vesicles to overcome drug-resistant cancer through mitochondrial-dependent cell death

Multidrug resistance (MDR) is a major challenge in cancer chemotherapy. Nanoparticles as drug delivery systems (DDSs) show promise for MDR cancer therapy. However, current DDSs require sophisticated design and construction based on xenogeneic nanomaterials, evoking feasibility and biocompatibility concerns. Herein, a simple but versatile biological DDS (bDDS) composed of human red blood cell (RBC)-derived vesicles (RDVs) with excellent biocompatibility was surface-linked with doxorubicin (Dox) using glutaraldehyde (glu) to form Dox-gluRDVs that remarkably suppressed MDR in uterine sarcoma through a lysosomal-mitochondrial axis-dependent cell death mechanism. Dox-gluRDVs can efficiently deliver and accumulate Dox in lysosomes, bypassing drug efflux transporters and facilitating cellular uptake and retention of Dox in drug-resistant MES-SA/Dx5 cells. The transfer of lysosomal calcium to the mitochondria during mitochondria-lysosome contact due to lysosomal Dox accumulation may result in mitochondrial ROS overproduction, mitochondrial membrane potential loss, and activation of apoptotic signaling for the superior anti-MDR activity of Dox-gluRDVs in vitro and in vivo. This work highlights the great promise of RDVs to serve as a bDDS of Dox to overcome MDR cancers but also opens up a reliable strategy for lysosomal-mitochondrial axis-dependent cell death for fighting against other inoperable cancers.

High-precision non-invasive RBC and HGB detection system based on spectral analysis

Non-invasive blood composition analysis based on dynamic spectrum (DS) theory has gained significant attention due to its non-invasive, simple, and fast performance. However, most of the multi-wavelength photoplethysmography (PPG) detection devices used to obtain DS are composed of halogen light sources and spectrometers and cannot detect effective PPG signals in the visible light short band (400-620 nm), which limits the detection accuracy of blood components with significant absorption spectral differences in that band. Therefore, this paper designs a multi-wavelength spectral acquisition system that can measure high signal-to-noise ratio (SNR > 65 dB) PGG signals at wavelengths of 405, 430, 450, 505, 520, and 570 nm and combines this system with a halogen lamp spectrometer acquisition system for non-invasive blood component detection. Furthermore, this paper collects the DS of 272 subjects with the combined system and establishes a predictive model for DS with the content of red blood cell (RBC) and hemoglobin (HGB) components. The results show that, compared with the halogen lamp spectrometer acquisition system, the correlation coefficient (Rp) of RBC and HGB prediction model established by the combined system has increased by 0.0619 and 0.0489, respectively, and the root mean square error (RMSE) has decreased by 0.08 1e12/L and 0.85 g/L, which confirm the feasibility of the designed multi-wavelength spectrum acquisition system to enhance the accuracy of blood component detection.

Low-Dose Dietary Fish Oil Improves RBC Deformability without Improving Post-Transfusion Recovery in Mice

Long-chain polyunsaturated fatty acids (LC-PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary LC-PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. Female C57BL/6J mice consumed diets containing increasing amounts of fish oil (FO) ad libitum for 8 weeks. RBC deformability, filterability, and post-transfusion recovery (PTR) were evaluated before and after cold storage. Lipidomics and lipid peroxidation markers were evaluated in fresh and stored RBCs. High-dose dietary FO (50%, 100%) was associated with a reduction in RBC quality (i.e., in vivo lifespan, deformability, lipid peroxidation) along with a reduced 24 h PTR after cold storage. Low-dose dietary FO (6.25-12.5%) improved the filterability of fresh RBCs and reduced the lipid peroxidation of cold-stored RBCs. Although low doses of FO improved RBC deformability and reduced oxidative stress, no improvement was observed for the PTR of stored RBCs. The improvement in RBC deformability observed with low-dose FO supplementation could potentially benefit endurance athletes and patients with conditions resulting from reduced perfusion, such as peripheral vascular disease.

Diverse associations observed between pregnancy complications and RBC or plasma folates determined by an in-house developed LC-MS/MS method

BACKGROUND

As folates are essential for embryonic development and growth, it is necessary to accurately determine the levels of folates in plasma and red blood cells (RBCs) for clinical intervention. The aims of this study were to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantitation of folates in plasma and RBCs and to examine the association between plasma and RBC folate concentrations and gestational diabetes mellitus (GDM), gestational hypertension (GH) and preeclampsia (PE).

METHODS

With the in-house developed LC-MS/MS, a retrospective cross-sectional study was conducted. The healthy pregnant women of first- (n = 147), second- (n = 84) and third-trimester (n = 141) or the women diagnosed with GDM (n = 84), GH (n = 58) or PE (n = 23), that were aged between 22 and 46 years old and registered at our institute, were subjected for measurement of folic acid (FA) and 5-methyltetrahydrofolate (5-MTHF), followed by appropriate statistical association analysis.

RESULTS

The assay for simultaneous quantitation of FA and 5-MTHF in plasma and RBCs was linear, stable, with imprecision less than 15% and recoveries within ±10%. The lower limits of quantification for FA and 5-MTHF measurement in whole blood were 0.57 and 1.09 nmol/L, and in plasma were 0.5 and 1 nmol/L, respectively. In the association analysis, the patients with lower RBC folate level (<906 nmol/L) presented higher risks of PE development (OR 4.861 [95% CI 1.411-16.505]) by logistic regression and restricted cubic spline (RCS) regression in a nonlinear fashion. In addition, higher level of plasma folates in pregnancy was significantly associated with GH risk but may be protective for the development of GDM.

CONCLUSIONS

The in-house developed LC-MS/MS method for folates and metabolites in plasma or RBC showed satisfactory analytical performance for clinical application. Further, the levels of folates and metabolites were diversely associated with GDM, GH and PE development.

Red blood cell count and risk of adverse outcomes in patients with mildly reduced left ventricular ejection fraction

BACKGROUND

Anemia is associated with increased rates of heart failure (HF)-related mortality and hospitalization. No studies have focused on the association between the red blood cell (RBC) count and the prognosis of patients with HF with mildly reduced left ventricular ejection fraction (HFmrEF). We retrospectively analyzed the effect of the RBC count on outcome events in patients with HFmrEF.

METHODS

We investigated the association of the RBC count with outcome events in 1691 patients with HFmrEF (mean age: 68 years; 35% female) in Xiangtan Central Hospital. Using Cox proportional hazards models, the RBC count was assessed as both a continuous and categorical variable.

RESULTS

During follow-up (median: 33 months), cardiovascular death occurred in 168 patients (114 men and 54 women). After adjusting for established risk factors, each 1.0 × 1012 cell/L increase in the RBC count was associated with a 28% lower risk of cardiovascular death in men and a 43% lower risk in women. Patients with low RBC counts had a 0.5-fold higher risk of cardiovascular death than those with normal RBC counts. The hazard ratio for men was 1.42 (95% confidence interval [CI]: 1.07-1.89), and the hazard ratio for women was 1.79 (95% CI: 1.20-2.67). The RBC count was not significantly associated with the composite endpoint of cardiovascular death and HF readmission (cardiovascular events) (p > .05).

CONCLUSIONS

A decreased RBC count is associated with increased cardiovascular mortality in patients with HFmrEF. Correcting a low RBC count might potentially reduce the risk of cardiovascular death in patients with HFmrEF.

Production of Feline Universal Erythrocytes with Methoxy Polyethylene Glycol

Blood group mismatch in veterinary medicine is a significant problem in blood transfusion, sometimes leading to severe transfusion reactions and even patient death. Blood groups vary from species to species and there are three known blood groups in cats: A, B and AB. While A-type cats are most common, there is a shortage of feline B-type blood groups in cats. By using methoxy polyethylene glycol (mPEG) to protect antigenic epitopes on red blood cells (RBCs), we aimed to find the optimal conditions for the production of feline universal RBCs. The surfaces of feline A-type RBCs were treated with mPEG at various molecular weights and concentrations. Agglutination tests showed that the coating of feline A-type RBCs with mPEG of 20 kDa and 2 mM blocked hemagglutination to feline anti-A alloantibodies over 8 h. While no differences in RBC size and shape between intact and mPEG-treated RBCs were seen, coating RBCs with mPEG inhibited the binding of feline anti-A alloantibodies. Furthermore, the mPEG-treated RBCs did not cause spontaneous hemolysis or osmotic fragility, compared to control RBCs. According to a monocyte monolayer assay, mPEG treatment significantly reduced feline anti-A antibody-mediated phagocystosis of RBCs. These results confirm the potential of using activated mPEG on feline A-type RBC to create universal erythrocytes for transfusion to B-type cats.

Transfusion trigger in the critically ill with sepsis or septic shock: A prospective study

Background & objectives

Current practice around transfusion trigger in critically ill sepsis patients is not clear. Moreover, any association of haemoglobin trigger and other transfusion parameters such as age of red blood cells (RBCs) at transfusion and number of units of RBCs transfused with mortality and other adverse outcomes need further assessment.

Methods

In this prospective study, patients aged 18-70 yr and admitted to intensive care with a diagnosis of sepsis were included (n=108). Baseline demographic, clinical and laboratory parameters were noted and various transfusion data, i.e., haemoglobin trigger, number of units of RBCs and the age of RBCs were recorded. Following outcome data were collected: 28 and 90 day mortality, duration of mechanical ventilation, vasopressor therapy, intensive care unit (ICU) and hospital stay and requirement of renal replacement therapy.

Results

Of the total 108 participants, 78 (72.2%) survived till 28 days and 66 (61.1%) survived till 90 days. Transfusion trigger was 6.9 (6.7-7.1) g/dl [median (interquartile range)]. On multivariable logistic regression analysis, acute physiology and chronic health evaluation (APACHE) II [adjusted odds ratio (aOR) (95% confidence interval {CI}): 0.86 (0.78, 0.96); P=0.005], cumulative fluid balance (CFB) [aOR (95% CI): 0.99 (0.99, 0.99); P=0.005] and admission platelet count [aOR (95% CI): 1.69 (1.01, 2.84); P=0.043] were the predictors of 28 day mortality [model area under the receiver operating characteristics (AUROC) 0.81]. APACHE II [aOR (95% CI): 0.88 (0.81, 0.97); P=0.013], CFB [a OR (95% CI): 0.99977 (0.99962, 0.99993); P=0.044] and transfusion trigger [aOR (95% CI): 3 (1.07, 8.34); P=0.035] were the predictors of 90 day mortality (model AUROC: 0.82).

Interpretation & conclusions

In sepsis, patients admitted to the ICU, current practice suggests transfusion trigger is below 7 g/dl and it does not affect any adverse outcome including 28 day mortality.

Massive Transfusion Increases Serum Magnesium Concentration

(1) Background: The massive transfusion of packed red blood cells (RBCs) is a lifesaving procedure, but it is associated with complications, e.g., dysmagnesemia. Since magnesium is an intracellular ion, the transfused RBCs can significantly influence the magnesium concentration in the recipient's blood. (2) Methods: A retrospective study was performed among 49 patients hospitalized in the Central Clinical Hospital of the Medical University of Warsaw who received a massive blood transfusion (≥4 units/h). Data on laboratory results and patient history were collected from the hospital database. The intracellular RBCs magnesium concentration was measured in 231 samples using the colorimetric method. (3) Results: There were statistically significant changes in the mean serum magnesium concentration preoperatively and 24 h postoperatively (0.87 ± 0.13 vs. 1.03 ± 0.14, p < 0.00001) and 48 h postoperatively (0.87 ± 0.13 vs. 1.06 ± 0.15, p < 0.00001). Patients who died had significantly higher serum magnesium concentrations (p < 0.05). The median intracellular magnesium concentration in RBCs was 0.91 (0.55-1.8) mmol/L, which is below the reference values of 1.65-2.65 mmol/L. (4) Conclusions: Transfused RBCs significantly increased the serum magnesium concentration 24 h and 48 h postoperatively. It could be a result of mild hemolysis, as the median intracellular magnesium concentration in RBCs was below the reference values.

Alterations in the expression pattern of RBC membrane associated proteins (RMAPs) in whole body γ-irradiated Sprague Dawley rats

PURPOSE

Peripheral blood serum/plasma proteins are frequently studied for their potential use as radiation exposure biomarkers. Here we report RBC membrane associated proteins (RMAPs), which show alterations in expression level following whole-body γ-irradiation of rats at sub-lethal/lethal doses.

MATERIALS AND METHODS

RBCs from peripheral blood of Sprague Dawley rats were segregated using the Ficoll-Hypaque method, and membrane fractions were hypotonically isolated at various time points (6 h, 24 h, 48 h) after γ-irradiation at 2 Gy, 5 Gy, and 7.5 Gy doses. Following purification of proteins from these fractions, two-dimensional electrophoresis (2-DE) was carried out. Treatment induced differentially expressed protein spots (≥2 fold increase/decrease) were picked up, trypsinized, and identified using LC-MS/MS analysis. Western immunoblots using protein specific antibodies were used to confirm the results. Gene ontology and interactions of these proteins were also studied.

RESULTS

From a number of differentially expressed radiation-responsive 2-DE protein spots detected, eight were identified unequivocally using LC-MS/MS. Out of these, actin, cytoplasmic 1 (ACTB) showed detectable yet insignificant variation (<50%) in expression. In contrast, peroxiredoxin-2 (PRDX2) and 26S proteasome regulatory subunit RPN11 (PSMD14) were the two most prominently over-expressed proteins. Five more proteins, namely tropomyosin alpha-3 chain (TPM3), exosome component 6 (EXOSC6), isoform 4 of tropomyosin alpha-1 chain (TPM1), serum albumin (ALB), and the 55 kDa erythrocyte membrane protein (P55) showed distinct alteration in their expression at different time-points and doses. ALB, EXOSC6, and PSMD14 were the most responsive at 2 Gy, albeit at different time-points. While EXOSC6 and PSMD14 showed maximum over-expression (5-12 fold) at 6 h post-irradiation, ALB expression increased progressively (4 up to 7 fold) from 6 h to 48 h. TPM1 showed over-expression (2-3 fold) at all doses and time-points tested. TPM3 showed a dose-dependent response at all time-points studied; with no variation at 2 Gy, ∼2 fold increase at 5 Gy, and 3-6 fold at the highest dose used (7.5 Gy). The p55 protein was over-expressed (∼2.5 fold) only transiently at 24 h following the lethal (7.5 Gy) dose.

CONCLUSION

This is the first study to report γ-radiation induced alterations in the RBC membrane associated proteins. We are further evaluating the potential of these proteins as radiation biomarkers. Due to the abundance and easy use of RBCs, this approach can prove very useful for detecting ionizing radiation exposure.

Pentachlorophenol-induced hemotoxicity diminishes antioxidant potential and oxidizes proteins, thiols, and lipids in rat blood: An in vivo study

Pentachlorophenol (PCP) is an excessively used wood preservative and pesticide, which has resulted in human exposure raising concerns about its potential toxic effects. This study is designed to evaluate the hemotoxicity of PCP in adult rats. Wistar rats were orally administered PCP (25-150 mg/kg bw) for five days while untreated (control) rats received corn oil. Animals were sacrificed, blood was taken and fractionated into plasma and red blood cells (RBC). PCP administration increased methemoglobin formation but decreased methemoglobin reductase activity. Significantly increased hydrogen peroxide level indicates initiation of oxidative stress condition in blood. PCP increased the oxidation of thiols, proteins and lipids, lowered glutathione levels, and compromised the antioxidant status of RBC in treated rats. Enzymes of the pathways of glucose breakdown, glycolysis and phosphogluconate pathway, were inhibited. Markers of liver damage were increased in the plasma of PCP-treated rats suggesting hepatotoxicity. This was confirmed by histopathological analysis of stained liver sections. Activity of xanthine oxidase, a reactive oxygen species (ROS) generating pro-oxidant enzyme, was increased. These hematological changes could be a result of the increased generation of ROS or direct chemical transformation by transient reaction species. These results show that PCP induces redox imbalance, diminishes antioxidant potential, inhibits metabolic pathways, and oxidizes cellular components in rat blood. This study suggests an elaborated possible molecular mechanism of PCP toxicity, and similar compounds so that methods can be devised to minimize its damaging effect.

Causes of red blood cell loss during extracorporeal membrane oxygenation

BACKGROUND

Pediatric patients on extracorporeal membrane oxygenation (ECMO) often receive repeated red blood cell (RBC) transfusions. This study aims to quantify and characterize causes of RBC loss on ECMO.

METHODS

This retrospective, single-center, observational study includes 91 ECMO patients (age 1 day-20 years). An RBC loss index (RLI), equal to ml RBCs lost per liter of patient + circuit volume per hour, was calculated from the changes in hematocrit and transfused RBCs. To measure the contribution of RBC injury/activation, RBC extracellular vesicle (REV) generation was measured by flow cytometry.

RESULTS

Median RLI on ECMO was 1.9 ml/L/h, 13-fold higher than normal RBC production rate (0.15 ml/L/h) and equivalent to a 4.6 drop in hematocrit/day. Median RBC loss was higher in patients who died (2.95 ml/L/h) versus survived (1.70 ml/L/h, p = .0008). RLI correlated with transfusion rate (r2  = 0.71); however, transfusion rate (ml/kg) underestimated RBC loss in patients with large changes in hematocrit and over-estimated RBC loss in neonates where the circuit volume is greater than the patient blood volume. In non-bleeding patients, intravascular hemolysis represented 16% of total RBC loss and diagnostic phlebotomy 24%, suggesting that ~60% of RBC loss was due to other causes. REV generation was increased sevenfold to ninefold during ECMO.

DISCUSSION

RLI (ml/L/h) is a more reliable quantitative indicator of RBC loss than transfusion rate (ml/kg) for pediatric patients on ECMO. Phlebotomy and intravascular hemolysis only account for 40% of RBC loss in non-bleeding ECMO patients. High REV generation suggests sublethal damage and extravascular clearance may be a cause of RBC loss on ECMO.

Curcumin from Curcuma longa Linn. (Family: Zingiberaceae) attenuates hypochlorous acid-induced cytotoxicity and oxidative damage to human red blood cells

Hypochlorous acid (HOCl) is a major oxidant produced by activated neutrophils via the myeloperoxidase catalyzed reaction. The production of HOCl eliminates a wide range of pathogens. However, HOCl can also cause significant oxidative damage in cells and tissues where it is generated. The protective effect of curcumin was studied on HOCl-induced oxidative damage to human red blood cells (RBC). Isolated RBC were incubated with HOCl at 37 °C in absence or presence of different concentrations of curcumin. Hemolysates were prepared and assayed for various biochemical parameters. Treatment of RBC with HOCl alone increased hemolysis, protein carbonyls, heme degradation and chloramines as compared to untreated control cells. This was accompanied by reduction in glutathione level, total sulfhydryls and free amino groups. HOCl also lowered the activities of major antioxidant enzymes and diminished the antioxidant power of RBC. Pre-treatment of RBC with different concentrations of curcumin resulted in concentration-dependent attenuation in all these parameters while curcumin alone had no significant effect. Scanning electron microscopy showed that curcumin prevented HOCl-induced morphological changes in RBC and restored their normal biconcave shape. Thus curcumin can be used as a chemoprotective agent to mitigate HOCl-induced oxidative damage to cells. These results also explain the beneficial effects of curcumin against Helicobacter pylori induced stomach ulcers, caused by excessive production of HOCl at the site of bacterial infection.

Perioperative transfusion and long-term mortality after cardiac surgery: a meta-analysis

OBJECTIVES

Cardiac surgical procedures are associated with a high incidence of periprocedural blood loss and blood transfusion. Although both may be associated with a range of postoperative complications there is disagreement on the impact of blood transfusion on long-term mortality. This study aims to provide a comprehensive review of the published outcomes of perioperative blood transfusion, examined as a whole and by index procedure.

METHODS

A systematic review of perioperative blood transfusion cardiac surgical patients was conducted. Outcomes related to blood transfusion were analysed in a meta-analysis and aggregate survival data were derived to examine long-term survival.

RESULTS

Thirty-nine studies with 180,074 patients were identified, the majority (61.2%) undergoing coronary artery bypass surgery. Perioperative blood transfusions were noted in 42.2% of patients and was associated with significantly higher early mortality (OR 3.87, p < 0.001). After a median of 6.4 years (range 1-15), mortality remained significantly higher for those who received a perioperative transfusion (OR 2.01, p < 0.001). Pooled hazard ratio for long-term mortality similar for patients who underwent coronary surgery compared to isolated valve surgery. Differences in long-term mortality for all comers remained true when corrected for early mortality and when only including propensity matched studies.

CONCLUSIONS

Perioperative red blood transfusion appears to be associated with a significant reduction in long-term survival for patients after cardiac surgery. Strategies such as preoperative optimisation, intraoperative blood conservation, judicious use of postoperative transfusions, and professional development into minimally invasive techniques should be utilised where appropriate to minimise the need for perioperative transfusions.

Influence of Cucurbiturils on the Production of Reactive Oxygen Species by T- and B-Lymphocytes, Platelets and Red Blood Cells

Reactive oxygen species (ROS) are highly reactive chemical molecules containing oxygen. ROS play an important role in signaling and cell homeostasis at low and moderate concentrations. ROS could be a cause of damage to proteins, nucleic acids, lipids, membranes and organelles at high concentrations. There are a lot of cells that can produce ROS to maintain functional activity. It is known that metal nanoparticles can increase production of ROS in cells. However, the effect of cucurbiturils on ROS production is still unknown. In our study, we evaluated production of ROS by the immune (T-, B-lymphocytes, NK-cells) and non-immune cells (red blood cells, platelets), as well as tumor cells line (1301, K562) after treatment with cucurbiturils in vitro. Assessment of reactive oxide species (ROS) were provided by using dihydrorhodamine 123 (DHR 123). Fluorescence intensity and percentage DHR123 were measured by flow cytometry. Platelets, erythrocytes and activated T-helpers were changed the level of ROS production in response to stimulation with cucurbiturils. It was found that the percentage of these ROS-producing cells was reduced by cucurbiturils. Thus, cucurbiturils may affect the production of ROS by cells, but further research is needed in this area.

Visualization of multiphase pulsatile blood over single phase blood flow in a patient specific stenosed left coronary artery using image processing technique

BACKGROUND

Coronary arteries disease has been reported as one of the principal roots of deaths worldwide.

OBJECTIVE

The aim of this study is to analyze the multiphase pulsatile blood flow in the left coronary artery tree with stenosis.

METHODS

The 3D left coronary artery model was reconstructed using 2D computerized tomography (CT) scan images. The Red Blood Cell (RBC) and varying hemodynamic parameters for single and multiphase blood flow conditions were analyzed.

RESULTS

Results asserted that the multiphase blood flow modeling has a maximum velocity of 1.017 m/s and1.339 m/s at the stenosed region during the systolic and diastolic phases respectively. The increase in Wall Shear Stress (WSS) observed at the stenosed region during the diastole phase as compared during the systolic phase. It was also observed that the highest Oscillatory Shear Index (OSI) regions are found in the downstream area of stenosis and across the bifurcations. The increase in RBCs velocity from 0.45 m/s to 0.6 m/s across the stenosis was also noticed.

CONCLUSION

The computational multiphase blood flow analysis improves the understanding and accuracy of the complex flow conditions of blood elements (RBC and Plasma) and provides the progression of the disease development in the coronary arteries. This study helps to enhance the diagnosis of the blocked (stenosed) arteries more precisely compared to the single-phase blood flow modeling.

Advances in Microfluidics for Single Red Blood Cell Analysis

The utilizations of microfluidic chips for single RBC (red blood cell) studies have attracted great interests in recent years to filter, trap, analyze, and release single erythrocytes for various applications. Researchers in this field have highlighted the vast potential in developing micro devices for industrial and academia usages, including lab-on-a-chip and organ-on-a-chip systems. This article critically reviews the current state-of-the-art and recent advances of microfluidics for single RBC analyses, including integrated sensors and microfluidic platforms for microscopic/tomographic/spectroscopic single RBC analyses, trapping arrays (including bifurcating channels), dielectrophoretic and agglutination/aggregation studies, as well as clinical implications covering cancer, sepsis, prenatal, and Sickle Cell diseases. Microfluidics based RBC microarrays, sorting/counting and trapping techniques (including acoustic, dielectrophoretic, hydrodynamic, magnetic, and optical techniques) are also reviewed. Lastly, organs on chips, multi-organ chips, and drug discovery involving single RBC are described. The limitations and drawbacks of each technology are addressed and future prospects are discussed.

Personalized Dose of Adjuvant Imatinib in Patients with Gastrointestinal Stromal Tumors: Results from a Population Pharmacokinetic Analysis

Purpose

Imatinib is the first-line treatment for patients with gastrointestinal stromal tumors (GIST) after surgery. However, its pharmacokinetic profile varies remarkably between individuals and has not been well characterized in postoperative Chinese patients with GIST. Therefore, this study aimed to develop a population pharmacokinetic (PPK) model and recommend appropriate doses for different patients to achieve the target trough concentration in such a population.

Patients and Methods

A total of 110 surgically treated GIST patients were enrolled, of which 85 were applied to conduct a PPK analysis with a nonlinear mixed-effect model and 25 for external validation of the model. Demographic and biomedical covariates, as well as six single nucleotide polymorphisms were tested to explore the sources of variation in pharmacokinetic parameters of imatinib. Monte Carlo simulations were performed to establish the initial dosing regimens.

Results

A one-compartment model was established in postoperative GIST patients. The red blood cell count (RBC) and ABCG2 rs2231142 were observed to have a significant effect on the clearance of imatinib. The typical values estimated by the final model were 9.72 L/h for clearance (CL/F) and 229 L for volume of distribution (V/F). Different from the fixed dose regimen of 400 mg each day, patients carrying rs2231142 heterozygous type and with a lower level of RBC (2.9 × 10¹²/L), 300 mg imatinib daily is enough to achieve the target trough concentration. When RBC rises to 4.9 × 10¹²/L, 500 mg daily is recommended. For patients with rs2231142 GG genotype, 500 mg a day is required at RBCs of 3.9 × 10¹²/L and 4.9 × 10¹²/L.

Conclusion

RBC and rs2231142 contribute to the pharmacokinetic variation of imatinib and personalized dose recommendations based on patient characteristics may be necessary.

Prevalence and Risk Factors of Metabolic-Associated Fatty Liver Disease Among Hospital Staff

Background

The prevalence of metabolism-related fatty liver disease (MAFLD) has been rarely reported in hospital staffs. The aim of this study was to assess the prevalence and risk factors for MAFLD in hospital staffs aged ≥18 years.

Methods

Based on type B ultrasonic, hospital staffs who underwent medical examinations at the second Affiliated Hospital of Hainan Medical University from January 2022 to March 2022 were classified into health control group (661 subjects) and MAFLD group (223 subjects), demographic, biochemical and blood examination information were compared between 2 groups. Independent risk factors for MAFLD were determined by logistic regression. Predictive values of risk factors of MAFLD were evaluated by receiver operating characteristic (ROC) curves.

Results

The prevalence of MAFLD was 33.7%. Older age (OR=1.08, p<0.001), H. pylori infection (OR=0.234, p=0.02), triglyceride-glucose (TyG) (OR=7.001, p<0.001), low-density lipoprotein cholesterol (LDL-C) (OR=2.076, p=0.028), red blood cell (RBC) (OR=2.386, p=0.001), eating out (OR=0.048, p=0.001), regular exercise (OR=23.017, p<0.001), and overweight (OR=3.891, p=0.003) were independently associated factors for MAFLD. The AUC of model predicting MAFLD is 0.910 [95% CI (0.886, 0.934)], with 0.794 sensitivity, 0.908 specificity. The diagnostic value of model was higher in the female MAFLD group after stratified analysis according to gender. The model showed that TyG was the factor contributing more to MAFLD. The diagnostic value of TyG was higher in the female MAFLD group than male MAFLD group.

Conclusion

The prevalence of MAFLD among hospital staffs was 33.7%. TyG can be used to predict MAFLD especially for female hospital staffs for early intervention.

Circulating mitochondrial DNA is associated with anemia in newly diagnosed hematologic malignancies

Recent reports discovered that red blood cells (RBCs) could scavenge cell-free mitochondrial DNA (mtDNA), which drives the accelerated erythrophagocytosis and innate immune activation characterized by anemia and inflammatory cytokine production. However, the clinical value of the circulating mtDNA copy number alterations in hematologic malignancies is poorly understood. Our data showed that in comparison to healthy group, the patients group had significantly higher mtDNA and histone H4 levels. Moreover, we observed that RBC-bound mtDNA and histone H4 were negatively correlated with hemoglobin in patients. In addition, cytokines and chemokines levels in patients differed significantly from normal controls (21 higher, 7 lower). Our study suggested that both circulating mtDNA and histone H4 were associated with anemia in hematologic malignancies, which helps to further understand the potential mechanism of anemia development in patients with hematologic malignancies. This information may play a vital role in the specific therapeutic interventions for leukemia in the future.

Determination of the Assigned Values of Blood Cells by an Impedance Method for Hematological Reference Samples Used in Hematology External Quality Assessment (EQA) Programs

The research into and production of hematological reference samples used to implement an external quality assessment (EQA) to check the quality of hematology tests are necessary for hematology laboratories in Vietnam. In this research, the study team determined the assessment values of blood cell count (human RBCs, pseudo-leucocytes, and pseudo-platelets) by the impedance method used in hematology EQA programs. The hematological reference samples were controlled at three concentration levels: low, normal, and high. Determination of the assigned value (mean ± 2SD) was performed for the following hematology analyzer series by impedance method: ABX Micros 60, Celldyn 1700, and Mindray BC 2000. Each device was sent to 10 different laboratories for evaluation. Research results for assigned values of each model (ABX Micros 60, Celldyn 1700, and Mindray BC 2000) were determined at the three concentrations. For the ABX Micros 60 and Celldyn 1700 series, 80% of laboratories had analytical results within assigned values. For the Mindray BC 2000 series, 100% of laboratories had analytical results within assigned values. The measurement results for the number of human RBCs, pseudo-leucocytes, and pseudo-platelets on each analyzer were similar between the 10 laboratories; the results of the three hematology analyzer series using the impedance method were different and the difference was statistically significant (p < 0.05). Thus, hematological reference samples for measuring the number of blood cells meeting the standards so that they can evaluate the results of laboratories using the impedance method: ABX, Celldyn 1700, Mindray BC 2000.

Red Blood Cell Malfunction in COVID-19: Molecular Mechanisms and Therapeutic Targets

The world has been facing a pandemic for the past 2 years. COVID-19 still leads to millions of deaths worldwide, while deteriorating the global economy. The need for therapeutic targets, thus, remains. Interestingly, red blood cells, apart from gas exchange, also serve as modulators of innate and adaptive immunity. This function is accommodated mainly by surface molecules (proteins, lipids, and carbohydrates) and increased antioxidant capacity. However, under the circumstances of a disease state, red blood cells can become proinflammatory cells. Recent evidence has shown that, in the context of COVID-19, erythrocytes present protein oxidation, decreased antioxidant capacity, increased glycolysis, altered membrane lipidome, increased binding of Cytosine-Guanine (CpG) DNA and complement proteins, and low CD47 levels. These changes lead to an erythrocyte-dependent inflammation, which possibly participates in the hyperinflammation status of COVID-19. The current knowledge for the dysfunction of red blood cells during COVID-19 implies that the BAND3 protein and toll-like receptor 9 are potential therapeutic targets for COVID-19.

Impact of KIT Editing on Coat Pigmentation and Fresh Meat Color in Yorkshire Pigs

The white coat color of Yorkshire pigs is caused by the dominant white I allele, which has been associated with at least one copy of the 450-kb duplication encompassing the entire KIT gene and a splice mutation (G > A) at the first base of intron 17. The splice mutation in KIT has an adverse effect on pigmentation in mice. Therefore, removing the 450 kb duplications harboring the KIT copy with splice mutations is expected to affect Yorkshire pig pigmentation. In this study, we describe the use of a Yorkshire pig kidney cell strain with the I^?/I^Be-ed genotype, previously created by CRISPR-Cas9, as donor cells for somatic cell nuclear transfer to generate gene-edited Yorkshire pigs. The removal of the 450 kb duplications harboring the KIT copy with splice mutation did not alter the white coat color of Yorkshire pigs, which was confirmed by the absence of fully mature melanocytes and melanin accumulation in the hair follicles. Except for the improved transcription of tyrosinase, and slight increase in microphthalmia transcription factor and tyrosinase-related protein 1 protein expression, there was no significant impact of the removal of splice mutations on genes and signaling pathways (PI3K/AKT) involved in melanogenesis. However, the removal of the 450 kb duplications harboring the KIT copy with splice mutation substantially improved fresh meat color accompanied by significantly increased red blood cell number, which merits further investigation. Our study provides new insights into the role of structural mutations of the KIT gene in the formation of white coat color and erythropoiesis in Yorkshire pigs.

Urinary phthalate metabolites and anemia: Findings from the Korean National Environmental Health Survey (2015-2017)

BACKGROUND

Several animal studies have suggested an association between phthalate exposure and decreased hemoglobin levels. To address the lack of epidemiological evidence, we evaluated the association between urinary phthalate metabolite concentrations and hematologic indices by using nationally representative data from Korea.

METHODS

Data from 3722 adults included in the third stage (2015-2017) of the Korean National Environmental Health Survey (KONEHS) were used. The association between various urinary phthalate metabolites and hematologic indices (hemoglobin, hematocrit, mean corpuscular volume [MCV], and red blood cell [RBC], white blood cell [WBC], and platelet counts) was evaluated using linear regression analysis adjusted for potential confounders. Sex-stratified analysis was performed.

RESULTS

All urinary phthalate metabolites were negatively associated with hemoglobin levels. A two-fold increase in urinary mono-(2-ethyl-5-carboxy-pentyl) phthalate (MECPP), mono-carboxyoctyl phthalate (MCOP), mono-carboxyonyl phthalate (MCNP), and mono-(3-carboxypropyl) phthalate (MCPP) levels was associated with a -0.099 g/dL (95% confidence interval (CI), -0.137 to -0.060), -0.116 g/dL (95% CI, -0.156 to -0.076), -0.111 g/dL (95% CI, -0.154 to -0.068), and -0.144 g/dL (95% CI, -0.198 to -0.089) change in hemoglobin levels, respectively. The RBC count and MCV showed negative and positive associations, respectively, with urinary phthalate metabolite concentrations. WBC counts were positively associated with MECPP, MCOP, MCNP, and MCPP levels, whereas the platelet count showed no association with urinary phthalate metabolites.

CONCLUSIONS

Urinary phthalate metabolite concentration showed a negative association with hemoglobin level. Since this was a cross-sectional study, further longitudinal and experimental studies are needed to identify a clear causal linkage and the pathological mechanism underlying phthalate exposure and anemia.

Deep learning prediction of stroke thrombus red blood cell content from multiparametric MRI

BACKGROUND AND PURPOSE

Thrombus red blood cell (RBC) content has been shown to be a significant factor influencing the efficacy of acute ischemic stroke treatment. In this study, our objective was to evaluate the ability of convolutional neural networks (CNNs) to predict ischemic stroke thrombus RBC content using multiparametric MR images.

MATERIALS AND METHODS

Retrieved stroke thrombi were scanned ex vivo using a three-dimensional multi-echo gradient echo sequence and histologically analyzed. 188 thrombus R2*, quantitative susceptibility mapping and late-echo GRE magnitude image slices were used to train and test a 3-layer CNN through cross-validation. Data augmentation techniques involving input equalization and random image transformation were employed to improve network performance. The network was assessed for its ability to quantitatively predict RBC content and to classify thrombi into RBC-rich and RBC-poor groups.

RESULTS

The CNN predicted thrombus RBC content with an accuracy of 62% (95% CI 48-76%) when trained on the original dataset and improved to 72% (95% CI 60-84%) on the augmented dataset. The network classified thrombi as RBC-rich or poor with an accuracy of 71% (95% CI 58-84%) and an area under the curve of 0.72 (95% CI 0.57-0.87) when trained on the original dataset and improved to 80% (95% CI 69-91%) and 0.84 (95% CI 0.73-0.95), respectively, on the augmented dataset.

CONCLUSIONS

The CNN was able to accurately predict thrombus RBC content using multiparametric MR images, and could provide a means to guide treatment strategy in acute ischemic stroke.

Niche differentiation and symbiotic association among ammonia/nitrite oxidizers in a full-scale rotating biological contactor

Although the distribution of ammonia/nitrite oxidizers had been profiled in different habitats, current understanding is still limited regarding their niche differentiation in the integrated biofilm reactors, the symbiotic associations of ammonia/nitrite oxidizers, as well as the parasitic interaction between viruses and those functional organisms involved in the nitrogen cycle. Here, the integrated metagenomics and metatranscriptomics are applied to profile the ammonia/nitrite oxidizers communities and transcriptional activities changes along the flowpath of a concatenated full-scale rotating biological contactor (RBC) (frontend Stage-A and backend Stage-B). 19 metagenome-assembled genomes (MAGs) of ammonia/nitrite oxidizers were recovered by using a hybrid assembly approach, including four ammonia-oxidizing bacteria (AOB), two ammonia-oxidizing archaea (AOA), two complete ammonia oxidation bacteria (comammox), eight nitrite-oxidizing bacteria (NOB), and three anaerobic ammonium oxidation bacteria (anammox). Diverse AOB and anammox dominated Stage-A and collectively contributed to nitrogen conversion. With the decline of ammonia concentration along the flowpath, comammox and AOA appeared and increased in relative abundance in Stage-B, accounting for 8.8% of the entire community at the end of this reactor, and their dominating role in nitrogen turnover was indicated by the high transcription activity of their corresponding function genes. Moreover, the variation in the abundance of viruses infecting ammonia and nitrite oxidizers suggests that viruses likely act as a biotic factor mediating ammonia/nitrite oxidizer populations. This study demonstrates that complex factors shaped niche differentiation and symbiotic associations of ammonia/nitrite oxidizers in the RBC and highlights the importance of RBCs as model systems for the investigation of biotic and abiotic factors affecting the composition of microbiomes.

Novel O-Methylglucoside Derivatives of Flavanone in Interaction with Model Membrane and Transferrin

Flavonoids were biotransformed using various microorganisms, in order to obtain new compounds with potentially high biological activity. The aim of this work was to determine and compare the biological activity of four novel 6-methylflavanone O-methylglucosides. The tested compounds have the same flavonoid core structure and an attached O-methylglucose and hydroxyl group at different positions of ring A or B. The studies on their biological activity were conducted in relation to phosphatidylcholine membrane, erythrocytes and their membrane, and with human transferrin. These studies determined the compounds' toxicity and their impact on the physical properties of the membranes. Furthermore, the binding ability of the compounds to holo-transferrin was investigated. The obtained results indicate that used compounds bind to erythrocytes, change their shape and decrease osmotic fragility but do not disrupt the membrane structure. Furthermore, the used compounds ordered the area of the polar heads of lipids and increased membrane fluidity. However, the results indicate the binding of these compounds in the hydrophilic region of the membranes, like other flavonoid glycosides. The used flavanones formed complexes with transferrin without inducing conformational changes in the protein's structure. The relationship between their molecular structure and biological activity was discussed.

The amino acid sensor GCN2 controls red blood cell clearance and iron metabolism through regulation of liver macrophages

GCN2 (general control nonderepressible 2) is a serine/threonine-protein kinase that controls messenger RNA translation in response to amino acid availability and ribosome stalling. Here, we show that GCN2 controls erythrocyte clearance and iron recycling during stress. Our data highlight the importance of liver macrophages as the primary cell type mediating these effects. During different stress conditions, such as hemolysis, amino acid deficiency or hypoxia, GCN2 knockout (GCN2-/-) mice displayed resistance to anemia compared with wild-type (GCN2+/+) mice. GCN2-/- liver macrophages exhibited defective erythrophagocytosis and lysosome maturation. Molecular analysis of GCN2-/- cells demonstrated that the ATF4-NRF2 pathway is a critical downstream mediator of GCN2 in regulating red blood cell clearance and iron recycling.

Randomized clinical split-mouth study on a novel self-adhesive bulk-fill restorative vs. a conventional bulk-fill composite for restoration of class II cavities - results after three years

OBJECTIVES

This randomized prospective split-mouth study evaluated the clinical performance of a novel, tooth-colored, self-adhesive bulk-fill restorative (SABF, 3M) for restoration of class II cavities as compared to a conventional bulk-fill composite (Filtek One, 3M; FOBF) over 36 months. The null-hypothesis was that both materials perform equally regarding clinical success and performance according to the FDI clinical criteria and scoring system.

METHODS

30 patients received one SABF and one FOBF restoration each. For FOBF, Scotchbond Universal (3M) was used as adhesive (self-etch mode), whereas SABF was applied without adhesive. Two blinded examiners evaluated the restorations at baseline, 24 and 36 months using FDI criteria. Data were analyzed non-parametrically (χ²-tests; α=0.05).

RESULTS

29 patients were available for the 24- and 36-month examinations. Clinical success rate was 96.6% for both materials at 36-mo (one restoration failure due to secondary caries each). All other restorations revealed clinically acceptable FDI scores at all recalls. FOBF performed significantly better than SABF at all time points regarding surface lustre (p<0.001) and color match and translucency (p<0.001) and regarding marginal staining at 36-months (p=0.008). Marginal staining and marginal adaptation deteriorated significantly over time for both materials (both p<0.001).

CONCLUSIONS

The null-hypothesis could only partially be rejected. Both materials performed similarly regarding clinical success and performance within 36 months of clinical service, but SABF exhibited significantly inferior, but clinically fully acceptable esthetic properties as compared to FOBF. Both restorative materials showed clinically fully acceptable results over 36 months of clinical service and thus may be recommended for clinical use.

CLINICAL SIGNIFICANCE

The novel tooth-colored self-adhesive bulk-fill restorative exhibited clinically fully acceptable results over 36 months of clinical service, similarly to a conventional bulk-fill restorative used with a universal adhesive, but with slight shortcomings in esthetic properties. Therefore, both restorative materials may be recommended for clinical use.

Quantitation of methotrexate polyglutamates in human whole blood, erythrocytes and leukocytes collected via venepuncture and volumetric absorptive micro-sampling: a green LC-MS/MS-based method

Low-dose methotrexate (MTX) plays a key role in treatment of rheumatoid arthritis. However, not all patients respond satisfactorily, and no therapeutic drug monitoring has been implemented in clinical practice, despite the fact that MTX therapy has now been available for decades. Analysis of individual intracellular MTX metabolites among rheumatoid arthritis (RA) patients is hampered by the low intracellular concentrations of MTX-PGs which require a highly sensitive method to quantify. Here, we present a rapid and highly sensitive LC (HILIC) MS/MS method with LLOQ 0.1 nM, 0.8 nmol/L for each metabolite of MTX-PG_1-5 and MTX-PG_6-7 respectively. Over a linear range of 0.1-100 nM, 0.8-100 nmol/L for each metabolite of MTX-PG_1-5 and MTX-PG_6-7, respectively, the inter- and intra- accuracy and precision were within 15% of the nominal value for all MTX metabolites. The presented assay was used to assess and compare MTX metabolite concentrations extracted from four different matrices: red blood cells, plasma, peripheral blood mononuclear cells, and whole blood that have been collected either using traditional venepuncture or volumetric absorptive micro-sampling (VAMS) sampling techniques. The presented method not only improves analyte coverage and sensitivity as compared to other published methods; it also improves the greenness.

Plasmodium manipulates the expression of host long non-coding RNA during red blood cell intracellular infection

BACKGROUND

Parasites interact with their host through "direct" and/or "indirect" mechanisms. Plasmodium, for example, either mediates direct physical interactions with host factors or triggers the immune system of the host indirectly, leading to changes in infectious outcomes. Long non-coding RNAs (lncRNAs) participate in regulating biological processes, especially host-pathogen interactions. However, research on the role of host lncRNAs during Plasmodium infection is limited.

METHODS

A RNA sequencing method (RNA-seq) was used to confirm the differential expression profiles of lncRNAs in Plasmodium yeolii 17XL (P.y17XL)-infected BALB/c mice. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to elucidate the potential functions of Plasmodium-induced genes. Subsequently, the effect of specific lncRNAs on the modulation of immune-related signaling pathways in malaria was determined by fluorescence-activated cell sorting, western blot and enzyme-linked immunosorbent assay.

RESULTS

The data showed that in P.y17XL-infected BALB/c mice, Plasmodium upregulated the expression of 132 lncRNAs and downregulated the expression of 159 lncRNAs. Differentially expressed lncRNAs clearly associated with malaria infection were annotated, including four novel dominant lncRNAs: ENMSUSG00000111521.1, XLOC_038009, XLOC_058629 and XLOC_065676. GO and KEGG pathway analyses demonstrated that these four differentially expressed lncRNAs were associated with co-localized/co-expressed protein-coding genes that were totally enriched in malaria and with the transforming growth factor beta (TGF-β) signaling pathway. Using the models of P.y17XL-infected BALB/c mice, data certified that the level of TGF-β production and activation of TGF-β/Smad_2/3 signaling pathway were obviously changed in malaria infection.

CONCLUSIONS

These differentially expressed immune-related genes were deemed to have a role in the process of Plasmodium infection in the host via dendritic/T regulatory cells and the TGF-β/Smad_2/3 signaling pathway. The results of the present study confirmed that Plasmodium infection-induced lncRNA expression is a novel mechanism used by Plasmodium parasites to modify host immune signaling. These results further enhance current understanding of the interaction between Plasmodium and host cells.

Blood cell quantification on dry blood samples: toward patient-centric complete blood counts

Background: Performing complete blood counts from patients' homes could have a transformative impact on e-based healthcare. Blood microsampling and sample drying are enabling elements for patient-centric healthcare. The aim of this study was to investigate the potential of dry blood samples for image-based cell quantification of red and white blood cells. Methods: A manual sample preparation method was developed and tested for image-based red and white blood cell counting. Results & conclusion: Dry blood samples enable image-based cell counting of red and white blood cells with a good correlation to gold standard hematology analyzer data (average coefficient of variation <6.5%; R² >0.8) and resolve the basic morphology of white blood cell nuclei. The presented proof-of-principle study is a first step toward patient-centric complete blood counts.

Clodronate inhibits alloimmunization against distinct red blood cell alloantigens in mice

BACKGROUND

Alloimmunization can be a significant barrier to red blood cell (RBC) transfusion. While alloantigen matching protocols hold promise in reducing alloantibody formation, transfusion-dependent patients can still experience RBC alloimmunization and associated complications even when matching protocols are employed. As a result, complementary strategies capable of actively preventing alloantibody formation following alloantigen exposure are warranted.

STUDY DESIGN AND METHODS

We examined whether pharmacological removal of macrophages using clodronate may provide an additional strategy to actively inhibit RBC alloimmunization using two preclinical models of RBC alloimmunization. To accomplish this, mice were treated with clodronate, followed by transfusion of RBCs expressing the HOD (HEL, OVA, and Duffy) or KEL antigens. On days 5 and 14 post transfusion, anti-HOD or anti-KEL IgM and IgG antibodies were evaluated.

RESULTS

Low dose clodronate effectively eliminated key marginal zone macrophage populations from the marginal sinus. Prior treatment with clodronate, but not empty liposomes, also significantly inhibited IgM and IgG anti-HOD alloantibody formation following transfusion of HOD RBCs. Similar exposure to clodronate inhibited IgM and IgG antibody formation following KEL RBC transfusion.

CONCLUSIONS

Clodronate can inhibit anti-HOD and anti-KEL antibody formation following RBC transfusion in preclinical models. These results suggest that clodronate may provide an alternative approach to actively inhibit or prevent the development of alloantibodies following RBC transfusion, although future studies will certainly be needed to fully explore this possibility.

Modelling haemoglobin incremental loss on chronic red blood cell transfusions

BACKGROUND AND OBJECTIVES

Understanding the impact of red blood cell (RBC) lifespan, initial RBC removal, and transfusion intervals on patient haemoglobin (Hb) levels and total iron exposure is not accessible for chronic transfusion scenarios. This article introduces the first model to help clinicians optimize chronic transfusion intervals to minimize transfusion frequency.

MATERIALS AND METHODS

Hb levels and iron exposure from multiple transfusions were calculated from Weibull residual lifespan distributions, the fraction effete RBC removed within 24-h (X_e ) and the nominal Hb increment. Two-unit transfusions of RBCs initiated at patient [Hb] = 7 g/dl were modelled for different RBC lifespans and transfusion intervals from 18 to 90 days, and X_e from 0.1 to 0.5.

RESULTS

Increased X_e requires shorter transfusion intervals to achieve steady-state [Hb] of 9 g/dl as follows: 30 days between transfusions at X_e  = 0.5, 36 days at X_e  = 0.4, 42 days at X_e  = 0.3, 48 days at X_e  = 0.2 and 54 days at X_e  = 0.1. The same transfusion interval/X_e pairs result in a steady-state [Hb] = 8 g/dl when the RBC lifespan was halved. By reducing transfused RBC increment loss from 30% to 10%, annual transfusions were decreased by 22% with iron addition decreased by 24%. Acute dosing of iron occurs at the higher values of X_e on the day after a transfusion event.

CONCLUSION

Systematic trends in fractional Hb incremental loss X_e have been modelled and have a significant and calculatable impact on transfusion intervals and associated introduction of iron.

Effect of modern infusion pumps on RBC quality

BACKGROUND

Mechanical stress on red blood cells is associated with using infusion pumps for blood administration. Current standards in North America leave it to healthcare facilities to consult with manufacturers about infusion pump safety for transfusion; studies on various pumps and red blood cell (RBC) conditions are scarce.

STUDY DESIGN AND METHODS

RBC units were pumped through four infusion pumps on d22 (22 days postcollection), d40, d28 after gamma irradiation on d14 (I14d28), and d22 after irradiation on d21 (I21d22). For each experiment, three units were pooled and split among four bags. Samples were collected at gravity and after pumping at clinical nonemergency rates. Hemolysis %, microvesicles, potassium, lactate dehydrogenase, mechanical fragility index levels, and morphology evaluations were performed (n = 5-6).

RESULTS

Hemolysis levels of Piston and Linear Peristaltic pump samples were not different from hemolysis of corresponding gravity samples. Peristaltic samples had significantly higher hemolysis compared to gravity, and other pumps, however, maximum mean difference was limited to 0.05%. Pumping at 50 mL/h resulted in the highest hemolysis level. Change in hemolysis % due to pumping was significantly higher in d40 and I21d22 units. No combination of pumps and RBCs conditions led to hemolysis >0.8%. Besides hemolysis, lactate dehydrogenase release was the only marker that demonstrated some differences between infusions via pump versus gravity.

CONCLUSION

The pump design affects the degree of hemolysis. However, for all tested pumps and RBC conditions, this increase was minimal. Hemolysis measurement on d40 and I21d22 at 50 mL/h were concluded to be appropriate parameters for pump evaluation.

α-Synuclein-containing erythrocytic extracellular vesicles: essential contributors to hyperactivation of monocytes in Parkinson's disease

Background

Immune system dysfunction, including higher levels of peripheral monocytes and inflammatory cytokines, is an important feature of Parkinson’s disease (PD) pathogenesis, although the mechanism underlying the process remains to be investigated. In the central nervous system, it is well-known that α-synuclein (α-syn), a key protein involved in PD, activates microglia potently, and it is also reported that α-syn exists in the peripheral system, especially in erythrocytes or red blood cells (RBC) at exceedingly high concentration. The current study focused on the possibility that RBC-derived α-syn mediates the sensitization of peripheral monocytes in PD patients.

Methods

The hyperactivation of monocytes was assessed quantitatively by measuring mRNA levels of typical inflammatory cytokines (including IL-1β, IL-6 and TNF-α) and protein levels of secreted inflammatory cytokines (including pro-inflammatory cytokines: IL-1β, IL-6, TNF-α, IL-8, IFN-γ, IL-2, and IL-12p70 and anti-inflammatory cytokines: IL-4, IL-10, and IL-13). Western blot, nanoparticle tracking analysis and electron microscopy were used to characterize RBC-derived extracellular vesicles (RBC-EVs). Inhibitors of endocytosis and leucine-rich repeat kinase 2 (LRRK2), another key protein involved in PD, were used to investigate how these two factors mediated the process of monocyte sensitization by RBC-EVs.

Results

Increased inflammatory sensitization of monocytes was observed in PD patients and PD model mice. We found that α-syn-containing RBC-EVs isolated from PD model mice or free form oligomeric α-syn induced the inflammatory sensitization of THP-1 cells, and demonstrated that endocytosis was a requirement for this pathophysiological pathway. Furthermore, the hyperactivation of THP-1 cells induced by RBC-EVs was associated with increased LRRK2 production and kinase activity. The phenomenon of inflammatory sensitization of human monocytes and increased LRRK2 were also observed by the treatment of RBC-EVs isolated from PD patients.

Conclusions

Our data provided new insight into how hyperactivation of monocytes occurs in PD patients, and identified the central role played by α-syn-containing RBC-EVs in this process.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02413-1.

Inhibition of the Aquaporin-1 Cation Conductance by Selected Furan Compounds Reduces Red Blood Cell Sickling

In sickle cell disease (SCD), the pathological shift of red blood cells (RBCs) into distorted morphologies under hypoxic conditions follows activation of a cationic leak current (Psickle) and cell dehydration. Prior work showed sickling was reduced by 5-hydroxylmethyl-2-furfural (5-HMF), which stabilized mutant hemoglobin and also blocked the Psickle current in RBCs, though the molecular basis of this 5-HMF-sensitive cation current remained a mystery. Work here is the first to test the hypothesis that Aquaporin-1 (AQP1) cation channels contribute to the monovalent component of Psickle. Human AQP1 channels expressed in Xenopus oocytes were evaluated for sensitivity to 5-HMF and four derivatives known to have differential efficacies in preventing RBC sickling. Ion conductances were measured by two-electrode voltage clamp, and osmotic water permeability by optical swelling assays. Compounds tested were: 5-HMF; 5-PMFC (5-(phenoxymethyl)furan-2-carbaldehyde); 5-CMFC (5-(4-chlorophenoxymethyl)furan-2-carbaldehyde); 5-NMFC (5-(2-nitrophenoxymethyl)-furan-2-carbaldehyde); and VZHE006 (tert-butyl (5-formylfuran-2-yl)methyl carbonate). The most effective anti-sickling agent, 5-PMFC, was the most potent inhibitor of the AQP1 ion conductance (98% block at 100 µM). The order of sensitivity of the AQP1 conductance to inhibition was 5-PMFC > VZHE006 > 5-CMFC ≥ 5-NMFC, which corresponded with effectiveness in protecting RBCs from sickling. None of the compounds altered AQP1 water channel activity. Combined application of a selective AQP1 ion channel blocker AqB011 (80 µM) with a selective hemoglobin modifying agent 5-NMFC (2.5 mM) increased anti-sickling effectiveness in red blood cells from human SCD patients. Another non-selective cation channel known to be expressed in RBCs, Piezo1, was unaffected by 2 mM 5-HMF. Results suggest that inhibition of AQP1 ion channels and capacity to modify hemoglobin are combined features of the most effective anti-sickling agents. Future therapeutics aimed at both targets could hold promise for improved treatments for SCD.

How I investigate acquired megaloblastic anemia

In this review of megaloblastic anemia (MA), an overview of vitamin B₁₂ and folate body requirements, biochemical pathways, and laboratory testing strategies will be provided. However, the focus of this review is the classic and unique features of MA in blood and bone marrow. Acquired MA is a benign disorder for many, but can be detrimental for some. The clinical presentation can vary considerably, and the spectrum of symptoms and signs is diverse and quite broad. Prompt recognition and therapy are critical to prevent potential irreversible damage and clinical sequelae, especially in patients with vitamin B₁₂ deficiency. A delay in diagnosis of vitamin B₁₂ deficiency can result in significant neurologic sequelae that may not fully resolve with treatment, including in neonates and young infants. The blood and bone marrow features in MA can closely mimic thrombocytopenic purpura, myelodysplasia, and other myeloid neoplasms. Both pancytopenia and normal MCV at presentation are common in MA and raise unique challenges for the diagnostician. Partially treated MA is also a significant diagnostic "trap". MA is highly responsive to treatment, and patients tend to improve rapidly upon treatment initiation. However, the broad range of clinical and hematologic features makes the rapid, successful diagnosis of MA a unique challenge for the hematopathologist. Even in the era of state-of-the-art laboratory testing, a high suspicion is required.

Deuterated Linoleic Acid Attenuates the RBC Storage Lesion in a Mouse Model of Poor RBC Storage

Background: Long-chain polyunsaturated fatty acids (PUFAs) are important modulators of red blood cell (RBC) rheology. Dietary PUFAs are readily incorporated into the RBC membrane, improving RBC deformability, fluidity, and hydration. However, enriching the lipid membrane with PUFAs increases the potential for peroxidation in oxidative environments (e.g., refrigerated storage), resulting in membrane damage. Substitution of bis-allylic hydrogens with deuterium ions in PUFAs decreases hydrogen abstraction, thereby inhibiting peroxidation. If lipid peroxidation is a causal factor in the RBC storage lesion, incorporation of deuterated linoleic acid (DLA) into the RBC membrane should decrease lipid peroxidation, thereby improving RBC lifespan, deformability, filterability, and post-transfusion recovery (PTR) after cold storage. Study Design and Methods: Mice associated with good (C57BL/6J) and poor (FVB) RBC storage quality received diets containing 11,11-D2-LA Ethyl Ester (1.0 g/100 g diet; deuterated linoleic acid) or non-deuterated LA Ethyl Ester (control) for 8 weeks. Deformability, filterability, lipidomics, and lipid peroxidation markers were evaluated in fresh and stored RBCs. Results: DLA was incorporated into RBC membranes in both mouse strains. DLA diet decreased lipid peroxidation (malondialdehyde) by 25.4 and 31% percent in C57 mice and 12.9 and 79.9% in FVB mice before and after cold storage, respectively. In FVB, but not C57 mice, deformability filterability, and post-transfusion recovery were significantly improved. Discussion: In a mouse model of poor RBC storage, with elevated reactive oxygen species production, DLA attenuated lipid peroxidation and significantly improved RBC storage quality.

Risk and Safety Perceptions Contribute to Transfusion Decisions in Coronary Artery Bypass Grafting

Variability persists in intraoperative red blood cell (RBC) transfusion rates, despite evidence supporting associated adverse sequelae. We evaluated whether beliefs concerning transfusion risk and safety are independently associated with the inclination to transfuse. We surveyed intraoperative transfusion decision-makers from 33 cardiac surgery programs in Michigan. The primary outcome was a provider's reported inclination to transfuse (via a six-point Likert Scale) averaged across 10 clinical vignettes based on Class IIA or IIB blood management guideline recommendations. Survey questions assessed hematocrit threshold for transfusion ("hematocrit trigger"), demographic and practice characteristics, years and case-volume of practice, knowledge of transfusion guidelines, and provider attitude regarding perceived risk and safety of blood transfusions. Linear regression models were used to estimate the effect of these variables on transfusion inclination. Mixed effect models were used to quantify the variation attributed to provider specialties and hematocrit triggers. The mean inclination to transfuse was 3.2 (might NOT transfuse) on the survey Likert scale (SD: .86) across vignettes among 202/413 (48.9%) returned surveys. Hematocrit triggers ranged from 15% to 30% (average: 20.4%; SE: .18%). The inclination to transfuse in situations with weak-to-moderate evidence for supporting transfusion was associated with a provider's hematocrit trigger (p < .01) and specialty. Providers believing in the safety of transfusions were significantly more likely to transfuse. Provider specialty and belief in transfusion safety were significantly associated with a provider's hematocrit trigger and likelihood for transfusion. Our findings suggest that blood management interventions should target these previously unaccounted for blood transfusion determinants.

Quantifying salt sensitivity

Inner surfaces of blood vessels and outer surfaces of erythrocytes are coated with a negatively charged protective film of proteoglycans, which serves as an effective buffer system for the positively charged sodium ions. If this protective coating is poorly developed or impaired, it loses its buffering capacity. As a consequence, the organism becomes increasingly sensitive to sodium, which in the long run leads to organ damage, especially if daily salt consumption is high. Recently, it has become possible to quantify salt sensitivity using a technically simple method - the salt blood test (SBT). Aim of this mini-review is to explain the physiological concept underlying the SBT and its potential practical relevance in the prevention of cardiovascular disease.

Automatic Detection and Counting of Blood Cells in Smear Images Using RetinaNet

A complete blood count is one of the significant clinical tests that evaluates overall human health and provides relevant information for disease diagnosis. The conventional strategies of blood cell counting include manual counting as well as counting using the hemocytometer and are tedious and time-consuming tasks. This research-based paper proposes an automatic software-based alternative method to count blood cells accurately using the RetinaNet deep learning network, which is used to recognize and classify objects in microscopic images. After training, the network automatically recognizes and counts red blood cells, white blood cells, and platelets. We tested a model trained on smear images and found that the trained model has generalized capabilities. We assessed the quality of detection and cell counting using performance measures, such as accuracy, sensitivity, precision, and F1-score. Moreover, we studied the dependence of the confidence thresholds and the number of learning epochs on the obtained results of recognition and counting. We compared the performance of the proposed approach with those obtained by other authors who dealt with the subject of cell counting and show that object detection and labeling can be an additional advantage in the task of counting objects.

The Value of a Complete Blood Count (CBC) for Sepsis Diagnosis and Prognosis

Sepsis represents an important global health burden due to its high mortality and morbidity. The rapid detection of sepsis is crucial in order to prevent adverse outcomes and reduce mortality. However, the diagnosis of sepsis is still challenging and many efforts have been made to identify reliable biomarkers. Unfortunately, many investigated biomarkers have several limitations that do not support their introduction in clinical practice, such as moderate diagnostic and prognostic accuracy, long turn-around time, and high-costs. Complete blood count represents instead a precious test that provides a wealth of information on individual health status. It can guide clinicians to early-identify patients at high risk of developing sepsis and to predict adverse outcomes. It has several advantages, being cheap, easy-to-perform, and available in all wards, from the emergency department to the intensive care unit. Noteworthy, it represents a first-level test and an alteration of its parameters must always be considered within the clinical context, and the eventual suspect of sepsis must be confirmed by more specific investigations. In this review, we describe the usefulness of basic and new complete blood count parameters as diagnostic and prognostic biomarkers of sepsis.

CAD/CAM Resin-Based Composites for Use in Long-Term Temporary Fixed Dental Prostheses

The aim of this in vitro study was to analyse the performance of CAD/CAM resin-based composites for the fabrication of long-term temporary fixed dental prostheses (FDP) and to compare it to other commercially available alternative materials regarding its long-term stability. Four CAD/CAM materials [Structur CAD (SC), VITA CAD-Temp (CT), Grandio disc (GD), and Lava Esthetic (LE)] and two direct RBCs [(Structur 3 (S3) and LuxaCrown (LC)] were used to fabricate three-unit FDPs. 10/20 FDPs were subjected to thermal cycling and mechanical loading by chewing simulation and 10/20 FDPs were stored in distilled water. Two FDPs of each material were forwarded to additional image diagnostics prior and after chewing simulation. Fracture loads were measured and data were statistically analysed. SC is suitable for use as a long-term temporary (two years) three-unit FDP. In comparison to CT, SC featured significantly higher breaking forces (SC > 800 N; CT < 600 N) and the surface wear of the antagonists was (significantly) lower and the abrasion of the FDP was similar. The high breaking forces (1100–1327 N) of GD and the small difference compared to LE regarding flexural strength showed that the material might be used for the fabrication of three-unit FDPs. With the exception of S3, all analysed direct or indirect materials are suitable for the fabrication of temporary FDPs.