Improved Erythrocyte Deformability Induced by Sodium-Glucose Cotransporter 2 Inhibitors in Type 2 Diabetic Patients.

PURPOSE: Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are antidiabetic drugs that improve cardiovascular outcomes. Hemoglobin and hematocrit values increase after SGLT-2 inhibitor administration. Although these factors increase blood viscosity and the risk of cardiovascular disease, SGLT-2 inhibitors have protective effects on the cardiovascular system. The mechanisms for this paradoxical phenomenon remain unclear, and the effect of SGLT-2 inhibitors on hemorheology has not been studied. METHODS: We evaluated the hemorheological parameters of 63 patients of whom 38 received metformin with a dipeptidyl peptidase 4 (DPP-4) inhibitor, while 25 received metformin with SGLT-2 inhibitor. Blood viscosity was measured using a cone-and-plate viscometer, erythrocyte aggregation was measured using a modified erythrocyte sedimentation rate method, and erythrocyte membrane fluctuation was measured as deformability, using a diffraction optical tomography. RESULTS: Both blood viscosity and erythrocyte aggregation increased in the SGLT-2 inhibitor group, although erythrocyte deformability was significantly improved compared with that of the DPP-4 inhibitor group (DPP-4 inhibitor 43.71 ± 5.13 nm; SGLT-2 inhibitor 53.88 ± 4.88 nm; p < 0.001). When the two groups were compared after propensity score matching, no differences in blood viscosity at high shear rates and erythrocyte aggregation were observed, although erythrocyte deformability was significantly improved in the SGLT-2 inhibitor group (DPP-4 inhibitor 45.01 ± 5.28 nm; SGLT-2 inhibitor 53.14 ± 4.72 nm; p = 0.001). CONCLUSION: This study demonstrates that erythrocyte deformability was improved in the SGLT-2 inhibitor group compared with that in the DPP-4 inhibitor group. This improvement in erythrocyte deformability is expected to have a protective effect on the cardiovascular system.

Impact of small fractions of abnormal erythrocytes on blood rheology.

Red blood cell (RBC) populations are inherently heterogeneous, given mature RBC lack the transcriptional machinery to re-synthesize proteins affected during in vivo aging. Clearance of older, less functional cells thus aids in maintaining consistent hemorheological properties. Scenarios occur, however, where portions of mechanically impaired RBC are re-introduced into blood (e.g., damaged from circulatory support, blood transfusion) and may alter whole blood fluid behavior. Given such perturbations are associated with poor clinical outcomes, determining the tolerable level of abnormal RBC in blood is valuable. Thus, the current study aimed to define the critical threshold of blood fluid properties to re-infused physically-impaired RBC. Cell mechanics of RBC were impaired through membrane cross-linking (glutaraldehyde) or intracellular oxidation (phenazine methosulfate). Mechanically impaired RBC were progressively re-introduced into the native cell population. Negative alterations of cellular deformability and high shear blood viscosity were observed following additions of only 1-5% rigidified RBC. Low-shear blood viscosity was conversely decreased following addition of glutaraldehyde-treated cells; high-resolution microscopy of these mixed cell populations revealed decreased capacity to form reversible aggregates and decreased aggregate size. Mixed RBC populations, when exposed to supraphysiological shear, presented with compounded mechanical impairment. Collectively, key determinants of blood flow behavior are sensitive to mechanical perturbations in RBC, even when only 1-5% of the cell population is affected. Given this fraction is well-below the volume of rigidified RBC introduced during circulatory support or transfusion practice, it is plausible that some adverse events following surgery and/or transfusion may be related to impaired blood fluidity.

Effects of osmolality and solutes on the morphology of red blood cells according to three-dimensional refractive index tomography.

Phosphate-buffered saline (PBS) and Alsever's solution (AS) are frequently used as media in blood-related studies, while 0.9% normal saline (NS) is frequently used in transfusion medicine. Despite the frequent use, the effects of these solutions on the shape and volume of red blood cells (RBCs) have not been reported. We collected blood samples from five healthy adults and used three-dimensional refractive index tomography to investigate the changes in the morphology of RBCs caused by changes in osmolality and solutes at the single-cell level. After diluting 2 µL of RBCs 200-fold with each solution (PBS, AS, and 0.9% NS), 40 randomly selected RBCs were microscopically observed. RBC shape was measured considering sphericity, which is a dimensionless quantity ranging from 0 (flat) to 1 (spherical). RBCs in plasma or AS showed a biconcave shape with a small sphericity, whereas those in 0.9% NS or PBS showed a spherical shape with a large sphericity. Moreover, we confirmed that sodium chloride alone could not elicit the biconcave shape of RBCs, which could be maintained only in the presence of an osmotic pressure-maintaining substance, such as glucose or mannitol. Although 0.9% NS solution is one of the most commonly used fluids in hematology and transfusion medicine, RBCs in 0.9% NS or PBS are not biconcave. Therefore, as the debate on the use of NS continues, future clinical studies or applications should consider the effect of glucose or mannitol on the shape of RBCs.

Erythrocyte Deformability and Na,K-ATPase Activity in Various Pathophysiological Situations and Their Protection by Selected Nutritional Antioxidants in Humans.

The physicochemical and functional properties of erythrocytes are worsened in a variety of diseases. Erythrocyte deformability refers to their ability to adjust their shape according to external forces exerted against them in the circulation. It is influenced by the functionality of the Na,K-ATPase enzyme, which is localized in their membranes. The proposed review is focused on knowledge regarding changes in erythrocyte Na,K-ATPase activity, and their impact on erythrocyte deformability in various pathophysiological situations observed exclusively in human studies, as well as on the potential erytroprotective effects of selected natural nutritional antioxidants. A clear link between the erythrocyte properties and the parameters of oxidative stress was observed. The undesirable consequences of oxidative stress on erythrocyte quality and hemorheology could be at least partially prevented by intake of diverse antioxidants occurring naturally in foodstuffs. Despite intensive research concerning the effect of antioxidants, only a small number of investigations on erythrocyte properties in humans is available in databases. It is worth shifting attention from animal and in vitro experiments and focusing more on antioxidant administration in human studies in order to establish what type of antioxidant, in what concentration, and in which individuals it may provide a beneficial effect on the human organism, by protecting erythrocyte properties.

Beneficial Effect of Quercetin on Erythrocyte Properties in Type 2 Diabetic Rats.

Diabetes mellitus is characterized by tissue oxidative damage and impaired microcirculation, as well as worsened erythrocyte properties. Measurements of erythrocyte deformability together with determination of nitric oxide (NO) production and osmotic resistance were used for the characterization of erythrocyte functionality in lean (control) and obese Zucker diabetic fatty (ZDF) rats of two age categories. Obese ZDF rats correspond to prediabetic (younger) and diabetic (older) animals. As antioxidants were suggested to protect erythrocytes, we also investigated the potential effect of quercetin (20 mg/kg/day for 6 weeks). Erythrocyte deformability was determined by the filtration method and NO production using DAF-2DA fluorescence. For erythrocyte osmotic resistance, we used hemolytic assay. Erythrocyte deformability and NO production deteriorated during aging-both were lower in older ZDF rats than in younger ones. Three-way ANOVA indicates improved erythrocyte deformability after quercetin treatment in older obese ZDF rats only, as it was not modified or deteriorated in both (lean and obese) younger and older lean animals. NO production by erythrocytes increased post treatment in all experimental groups. Our study indicates the potential benefit of quercetin treatment on erythrocyte properties in condition of diabetes mellitus. In addition, our results suggest potential age-dependency of quercetin effects in diabetes that deserve additional research.

Tadalafil impacts the mechanical properties of Plasmodium falciparum gametocyte-infected erythrocytes.

Plasmodium falciparum gametocytes modify the mechanical properties of their erythrocyte host to persist for several weeks in the blood circulation and to be available for mosquitoes. These changes are tightly regulated by the plasmodial phosphodiesterase delta that decreases both the stiffness and the permeability of the infected host cell. Here, we address the effect of the phosphodiesterase inhibitor tadalafil on deformability and permeability of gametocyte-infected erythrocytes. We show that this inhibitor drastically increases isosmotic lysis of gametocyte-infected erythrocytes and impairs their ability to circulate in an in vitro model for splenic retention. These findings indicate that tadalafil represents a novel drug lead potentially capable of blocking malaria parasite transmission by impacting gametocyte circulation.

Spectroscopic Signature of Red Blood Cells in a D-Galactose-Induced Accelerated Aging Model.

This work presents a semi-quantitative spectroscopic approach, including FTIR-ATR and Raman spectroscopies, for the biochemical analysis of red blood cells (RBCs) supported by the biochemical, morphological and rheological reference techniques. This multi-modal approach provided the description of the RBC alterations at the molecular level in a model of accelerated aging induced by administration of D-galactose (D-gal), in comparison to natural aging. Such an approach allowed to conclude that most age-related biochemical RBC membrane changes (a decrease in lipid unsaturation and the level of phospholipids, or an increase in acyl chain shortening) as well as alterations in the morphological parameters and RBC deformability are well reflected in the D-gal model of accelerated aging. Similarly, as in natural aging, a decrease in LDL level in blood plasma and no changes in the fraction of glucose, creatinine, total cholesterol, HDL, iron, or triglycerides were observed during the course of accelerated aging. Contrary to natural aging, the D-gal model led to an increase in cholesterol esters and the fraction of total esterified lipids in RBC membranes, and evoked significant changes in the secondary structure of the membrane proteins. Moreover, a significant decrease in the phosphorous level of blood plasma was specific for the D-gal model. On the other hand, natural aging induced stronger changes in the secondary structures of the proteins of the RBCs' interior. This work proves that research on the aging mechanism, especially in circulation-related diseases, should employ the D-gal model with caution. Nonetheless, the D-gal model enables to imitate age-related rheological alterations in RBCs, although they are partially derived from different changes observed in the RBC membrane at the molecular level.

In vitro alteration on erythrocytes mechanical properties by propofol, remifentanil and vecuronium.

Several studies report flow disturbance and microcirculation disorders upon anesthesia treatment. These alterations are often related to blood rheology changes. In this work, it was attempted to make a detailed description of the alterations in erythrocyte mechanical properties by the action of propofol, remifentanil, and vecuronium. For this, an in vitro study was performed on red blood cell samples from healthy donors incubated with solutions of propofol (4 µg/mL whole blood), remifentanil (10 ng/mL plasma), and vecuronium (0.15 µg/mL plasma). Erythrocyte viscoelastic parameters were determined by octuplicate using a Reómetro Eritrocitario. Also, a Wilcoxon signed rank-test with Yates correction for continuity was performed to analyze the overall alteration in the mechanical properties of erythrocytes. Statistical analysis showed that the three studied anesthetics changed the erythrocyte mechanical properties at different parts of the membrane. These results would imply an interaction of these anesthetics with the erythrocyte membrane. Finally, this could conduce to alterations in microcirculation.

Calcium/protein kinase C signaling mechanisms in shear-induced mechanical responses of red blood cells.

Red blood cell (RBC) deformability has vital importance for microcirculation in the body, as RBCs travel in narrow capillaries under shear stress. Deformability can be defined as a remarkable cell ability to change shape in response to an external force which allows the cell to pass through the narrowest blood capillaries. Previous studies showed that RBC deformability could be regulated by Ca2+/protein kinase C (PKC) signaling mechanisms due to the phosphorylative changes in RBC membrane proteins by kinases and phosphatases. We investigated the roles of Ca2+/PKC signaling pathway on RBC mechanical responses and impaired RBC deformability under continuous shear stress (SS). A protein kinase C inhibitor Chelerythrine, a tyrosine phosphatase inhibitor Calpeptin, and a calcium channel blocker Verapamil were applied into human blood samples in 1 micromolar concentration. Samples with drugs were treated with or without 3 mM Ca2+. A shear stress at 5 Pa level was applied to each sample continuously for 300 s. RBC deformability was measured by a laser-assisted optical rotational cell analyzer (LORRCA) and was calculated as the change in elongation index (EI) of RBC upon a range of shear stress (SS, 0.3-50 Pa). RBC mechanical stress responses were evaluated before and after continuous SS through the parameterization of EI-SS curves. The drug administrations did not produce any significant alterations in RBC mechanical responses when they were applied alone. However, the application of the drugs together with Ca2+ substantially increased RBC deformability compared to calcium alone. Verapamil significantly improved Ca2+-induced impairments of deformability both before and after 5 Pa SS exposure (p < 0.0001). Calpeptin and Chelerythrine significantly ameliorated impaired deformability only after continuous SS (p < 0.05). Shear-induced improvements of deformability were conserved by the drug administrations although shear-induced deformability was impaired when the drugs were applied with calcium. The blocking of Ca2+ channel by Verapamil improved impaired RBC mechanical responses independent of the SS effect. The inhibition of tyrosine phosphatase and protein kinase C by Calpeptin and Chelerythrine, respectively, exhibited ameliorating effects on calcium-impaired deformability with the contribution of shear stress. The modulation of Ca2+/PKC signaling pathway could regulate the mechanical stress responses of RBCs when cells are under continuous SS exposure. Shear-induced improvements in the mechanical properties of RBCs by this signaling mechanism could facilitate RBC flow in the microcirculation of pathophysiological disorders, wherein Ca2+ homeostasis is disturbed and RBC deformability is reduced.

Metabolic rejuvenation upgrades circulatory functions of red blood cells stored under blood bank conditions.

BACKGROUND: Red blood cells (RBC) change upon hypothermic conservation, and storage for 6 weeks is associated with the short-term clearance of 15% to 20% of transfused RBCs. Metabolic rejuvenation applied to RBCs before transfusion replenishes energetic sources and reverses most storage-related alterations, but how it impacts RBC circulatory functions has not been fully elucidated. STUDY DESIGN AND METHODS: Six RBC units stored under blood bank conditions were analyzed weekly for 6 weeks and rejuvenated on Day 42 with an adenine-inosine-rich solution. Impact of storage and rejuvenation on adenosine triphosphate (ATP) levels, morphology, accumulation of storage-induced microerythrocytes (SMEs), elongation under an osmotic gradient (by LORRCA), hemolysis, and phosphatidylserine (PS) exposure was evaluated. The impact of rejuvenation on filterability and adhesive properties of stored RBCs was also assessed. RESULTS: Rejuvenation of RBCs restored intracellular ATP to almost normal levels and decreased the PS exposure from 2.78% to 0.41%. Upon rejuvenation, the proportion of SME dropped from 28.2% to 9.5%, while the proportion of normal-shaped RBCs (discocytes and echinocytes 1) increased from 47.7% to 67.1%. In LORCCA experiments, rejuvenation did not modify the capacity of RBCs to elongate and induced a reduction in cell volume. In functional tests, rejuvenation increased RBC filterability in a biomimetic splenic filter (+16%) and prevented their adhesion to endothelial cells (-87%). CONCLUSION: Rejuvenation reduces the proportion of morphologically altered and adhesive RBCs that accumulate during storage. Along with the improvement in their filterability, these data show that rejuvenation improves RBC properties related to their capacity to persist in circulation after transfusion.

Effect of Hydrogen Sulfide on Deformability of Rat Erythrocytes.

The influence of a hydrogen sulfide donor NaHS (2×10-5-10-3 M) on the rat erythrocyte deformability was analyzed by laser diffractometry. NaHS (6×10-5 M) increased, while NaHS (10-3 M) reduced erythrocyte deformability. The effect of NaHS (6×10-5 M) was similar to that of NO donor sodium nitroprusside (SNP, 10-7 M). However, simultaneous use of NaHS (6×10-5 M) and SNP induced less pronounced changes in erythrocyte deformability than their individual application. It is likely H2S, similar to NO, is involved in the regulation of erythrocyte deformability in the microvascular bed.

Mixing commonly used crystalloid solutions with red blood cells in five common additives does not negatively impact hemolysis, aggregometry, or deformability.

BACKGROUND: Literature is beginning to challenge the belief that it is unsafe to coinfuse red blood cells (RBCs) with solutions other than isotonic saline. We recently showed that additive-free RBCs tolerated coincubation with Plasma-Lyte or catecholamines dissolved in normal saline (NS), though 5% dextrose in water (D5W) promoted hemolysis. Herein, we evaluate the effect of coincubating crystalloids on additive-preserved RBC hemolysis, aggregation, and membrane deformability. STUDY DESIGN AND METHODS: RBCs were coincubated 5 minutes with plasma, NS, Plasma-Lyte, lactated Ringer's (LR) or D5W (1 mL PRBC +131.3 µL solution). Samples were then assessed for hemolysis (free hemoglobin), aggregation (critical shear stress [mPa]), and membrane deformability (elongation index [EI]). Significance (P ≤ .05) by t test or ANOVA with post-hoc Tukey-Kramer test. RESULTS: Additive-prepared RBCs coincubated with crystalloid instead of plasma demonstrated: (a) no increase in hemolysis as indicated by plasma free hemoglobin levels that is likely to be clinically relevant; (b) no increase, but in some cases a decrease, in aggregation as indicated by critical shear stress; and (c) in some combinations, a deterioration in deformability. When present, the deformability decrease was likely clinically insignificant in degree, and always returned to normal when the crystalloid was subsequently diluted out with plasma. CONCLUSION: Our data suggest that additive-prepared RBCs coincubated for 5 minutes with any of four common crystalloids demonstrate no clinically relevant increased lysis, increased aggregation, or decreased deformability.

Inhibition of Band 3 tyrosine phosphorylation: a new mechanism for treatment of sickle cell disease.

Many hypotheses have been proposed to explain how a glutamate to valine substitution in sickle haemoglobin (HbS) can cause sickle cell disease (SCD). We propose and document a new mechanism in which elevated tyrosine phosphorylation of Band 3 initiates sequelae that cause vaso-occlusion and the symptoms of SCD. In this mechanism, denaturation of HbS and release of heme generate intracellular oxidants which cause inhibition of erythrocyte tyrosine phosphatases, thus permitting constitutive tyrosine phosphorylation of Band 3. This phosphorylation in turn induces dissociation of the spectrin-actin cytoskeleton from the membrane, leading to membrane weakening, discharge of membrane-derived microparticles (which initiate the coagulation cascade) and release of cell-free HbS (which consumes nitric oxide) and activates the endothelium to express adhesion receptors). These processes promote vaso-occlusive events which cause SCD. We further show that inhibitors of Syk tyrosine kinase block Band 3 tyrosine phosphorylation, prevent release of cell-free Hb, inhibit discharge of membrane-derived microparticles, increase sickle cell deformability, reduce sickle cell adhesion to human endothelial cells, and enhance sickle cell flow through microcapillaries. In view of reports that imatinib (a Syk inhibitor) successfully treats symptoms of sickle cell disease, we suggest that Syk tyrosine kinase inhibitors warrant repurposing as potential treatments for SCD.

Erythrocyte deformability and aggregation in morbidly obese women undergoing laparoscopic gastric bypass surgery and effects of oral omega-3 fatty acid supplementation.

BACKGROUND: An adequate erythrocyte function is vital for tissue oxygenation and wound healing. The erythrocyte membrane phospholipid composition plays an important role in erythrocyte function and administration of omega-3 fatty acids may provide a means to improve it. OBJECTIVE: To investigate peri-operative erythrocyte function and effects of oral omega-3 fatty acids in morbidly obese women undergoing gastric bypass surgeryMETHODS:Fifty-six morbidly obese women undergoing laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery were randomized between a low calorie diet (LCD) during 2 weeks or oral omega-3 poly-unsaturated fatty acids (n-3 PUFAs) and a normal diet during 4 weeks. Peri-operative blood samples were analyzed with the Lorrca MaxSIS Ektacytometer for erythrocyte deformability and aggregability. RESULTS: There were no significant differences in erythrocyte function between the groups at any time point. Only erythrocyte aggregability parameters were affected by surgery. At six month follow-up, aggregation index (AI) and cholesterol, glucose and insulin were significantly improved. CONCLUSIONS: In this study, oral Omega-3 supplementation did not affect erythrocyte function compared to a LCD. Six months after surgery a significant improvement in AI and metabolic parameters was observed in both groups, contributing to a reduction in the risk at thromboembolic and cardiovascular complications.

High-dose nitroglycerin administered during rewarming preserves erythrocyte deformability in cardiac surgery with cardiopulmonary bypass.

OBJECTIVE: We aimed to determine whether high-dose nitroglycerin, a nitric oxide donor, preserves erythrocyte deformability during cardiopulmonary bypass and examines the signaling pathway of nitric oxide in erythrocytes. METHODS: In a randomized and controlled fashion, forty-two patients undergoing cardiac surgery with hypothermic cardiopulmonary bypass were allocated to high-dose (N = 21) and low-dose groups (N = 21). During rewarming period, patients were given intravenous nitroglycerin with an infusion rate 5 and 1 µg·kg-1 ·min-1 in high-dose and low-dose groups, respectively. Tyrosine phosphorylation level of non-muscle myosin IIA in erythrocyte membrane was used as an index of erythrocyte deformability and analyzed using immunoblotting. RESULTS: Tyrosine phosphorylation of non-muscle myosin IIA was significantly enhanced after bypass in high-dose group (3.729 ± 1.700 folds, P = .011) but not low-dose group (1.545 ± 0.595 folds, P = .076). Phosphorylation of aquaporin 1, vasodilator-stimulated phosphoprotein, and focal adhesion kinase in erythrocyte membrane was also upregulated in high-dose group after bypass. Besides, plasma nitric oxide level was highly correlated with fold change of non-muscle myosin IIA phosphorylation (Pearson's correlation coefficient .871). CONCLUSIONS: High-dose nitroglycerin administered during cardiopulmonary bypass improves erythrocyte deformability through activating phosphorylation of aquaporin 1, vasodilator-stimulated phosphoprotein, and focal adhesion kinase in erythrocytes.

Erythrocyte deformability and aggregability in patients undergoing colon cancer surgery and effects of two infusions with omega-3 fatty acids.

BACKGROUND: An adequate erythrocyte function is vital for tissue oxygenation and wound healing. The erythrocyte membrane phospholipid composition plays an important role in erythrocyte function and administration of omega-3 fatty acids may provide a means to improve it. OBJECTIVE: To investigate peri-operative erythrocyte function and effects of omega-3 fatty acidsMETHODS:Forty-four patients undergoing elective laparoscopic colon resection for non-metastasized cancer were randomized between intravenous omega-3 poly-unsaturated fatty acids (n-3 PUFAs) or placebo (saline). Peri-operative blood samples were analyzed with a Lorrca MaxSIS Ektacytometer and erythrocyte membrane phospholipids were determined with gas chromatography. RESULTS: Patient and operation characteristics were equal between groups. There was a significant increase in erythrocyte membrane eicosapentaenoic acid (EPA) but not docosahexaenoic acid (DHA) in the n-PUFA group. There were no significant differences in erythrocyte deformability but the aggregation index (AI) was significantly lower and the aggregation half time (T½) was significantly higher in the n-3 PUFA group. CONCLUSION: This study confirms rapid changes in erythrocyte membrane phospholipid composition after administration of intravenous n-3 PUFAs. Erythrocyte deformability parameters were not affected but erythrocyte aggregability was decreased in the n-3 PUFA group. Further investigation is necessary to gain more insights in the effects of n-3 PUFA and the postoperative inflammatory response on erythrocyte function.

Nitrite may serve as a combination partner and a biomarker for the anti-cancer activity of RRx-001.

BACKGROUND: RRx-001 is an anti-cancer immunotherapeutic that increases the sensitivity of drug resistant tumors via multiple mechanisms which involve binding to hemoglobin and enhancing nitrite reductase activity of deoxyhemoglobin. OBJECTIVE: In the present study, the effect of clinically used doses of RRx-001 on erythrocyte deformability was examined. METHODS: A dose dependent effect of RRx-001 (1-1000 micro molar) on erythrocyte deformability was measured by ektacytometer under hypoxia (n = 8). Low dose RRx-001 (20 micro molar) in the presence of ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one), L-NAME (L-NG-Nitroarginine methyl ester) or nitrite were examined both in normoxia and hypoxia. Intracellular nitric oxide (NO) levels were measured fluorometrically with DAF-FM-DA. RESULTS: Higher doses of RRx-001 (100, 1000 micro molar) significantly decreased erythrocyte deformability under hypoxia (p < 0.01; p < 0.05, respectively). RRx-001 (20 micro molar), alone or in combination with ODQ or L-NAME, did not change deformability. However, RRx-001 and nitrite caused an increase in deformability (p < 0.01) under hypoxia. RRx-001 induced NO production was more pronounced in the presence of nitrite (p < 0.05). CONCLUSIONS: Co-administration of RRx-001 and nitrite under hypoxic conditions results in a significant increase in erythrocyte deformability that is related to increased NO production. We suggest that measurement of serum nitrite level in RRx-001 treated cancer patients should be routinely undertaken and supplemented if levels are low for maximal activity.

Insights into determinants of spleen injury in sickle cell anemia.

Spleen dysfunction is central to morbidity and mortality in children with sickle cell anemia (SCA). The initiation and determinants of spleen injury, including acute splenic sequestration (ASS) have not been established. We investigated splenic function longitudinally in a cohort of 57 infants with SCA enrolled at 3 to 6 months of age and followed up to 24 months of age and explored the respective contribution of decreased red blood cell (RBC) deformability and increased RBC adhesion on splenic injury, including ASS. Spleen function was evaluated by sequential 99mTc heated RBC spleen scintigraphy and high-throughput quantification of RBCs with Howell-Jolly bodies (HJBs). At 6 and 18 months of age, spleen filtration function was decreased in 32% and 50% of infants, respectively, whereas the median %HJB-RBCs rose significantly (from 0.3% to 0.74%). An excellent correlation was established between %HJB-RBCs and spleen scintigraphy results. RBC adhesion to laminin and endothelial cells increased with time. Adhesion to endothelial cells negatively correlated with splenic function. Irreversibly sickled cells (ISCs), used as a surrogate marker of impaired deformability, were detected at enrollment and increased significantly at 18 months. %ISCs correlated positively with %HJB-RBCs and negatively with splenic uptake, indicating a relationship between their presence in the circulation and spleen dysfunction. In the subgroup of 8 infants who subsequently experienced ASS, %ISCs at enrollment were significantly higher compared with the asymptomatic group, suggesting a major role of impaired deformability in ASS. Higher levels of %HJB-RBCs were observed after the occurrence of ASS, demonstrating its negative impact on splenic function.

Effect of curcumin extract against oxidative stress on both structure and deformation capability of red blood cell.

The normal deformability of erythrocytes plays an important role in ensuring blood mobility, erythrocyte longevity, and microcirculation, which is the ability of erythrocytes to change shapes in response to external forces. However, the effects of curcumin extracts on the deformability of erythrocytes have not yet been evaluated. Accordingly, in this study, we explored the effects of pre-treatment with curcumin extract on erythrocyte deformation and erythrocyte band 3 (SLC4A1; EB3) expression. We also evaluated the associations between EB3 expression and erythrocyte deformability induced by hydrogen peroxide. Blood samples were divided into the control group, pre-treatment group (treated with curcumin extract or vitamin C), and negative control group, and oxidant stress parameters, antioxidant status, erythrocyte deformability and elasticity, and EB3 modifications were evaluated using immunoblotting and immunofluorescence staining. Hydrogen peroxide significantly increased oxidative stress parameters, modulus elasticity values and clustered EB3 levels and induced conjugation of membrane proteins to form high-molecular-weight complexes (p < 0.05). Erythrocyte deformability and elasticity were significantly decreased in the treated groups compared with those in the control group. Overall, our findings suggested that pre-treatment with curcumin extracts increased antioxidant status, reduced EB3 cross-linking, and improved erythrocyte deformability, to an even better extent than vitamin C. These results provide important insights into the effects of treatment with curcumin extracts on erythrocyte damage and suggest that curcumin may have applications in antioxidant therapy.