Search

Vascular aging, characterized by structural and functional alterations of the vascular wall, is a hallmark of aging and is tightly related to the development of cardiovascular mortality and age-associated vascular pathologies. Over the last years, extensive and ongoing research has highlighted several sophisticated molecular mechanisms that are involved in the pathophysiology of vascular aging. A more thorough understanding of these mechanisms could help to provide a new insight into the complex biology of this non-reversible vascular process and direct future interventions to improve longevity. In this review, we discuss the role of the most important molecular pathways involved in vascular ageing including oxidative stress, vascular inflammation, extracellular matrix metalloproteinases activity, epigenetic regulation, telomere shortening, senescence and autophagy.

In this study, a novel viscosity measurement technique based on measuring the deflection of flexible (poly) dimethylsiloxane (PDMS) micropillars is presented. The experimental results show a nonlinear relationship between fluid viscosity and the deflection of micropillars due to viscoelastic properties of PDMS. A calibration curve, demonstrating this nonlinear relationship, is generated, and used to determine the viscosity of an unknown fluid. Using our method, viscosity measurements for Newtonian fluids (glycerol/water solutions) can be performed within 2-100 cP at shear rates gamma = 60.5-398.4 s(-1). We also measured viscosity of human whole blood samples (non-Newtonian fluid) yielding 2.7-5.1 cP at shear rates gamma = 120-345.1 s(-1), which compares well with measurements using conventional rotational vis-cometers (3.6-5.7 cP). With a sensitivity better than 0.5 cP, this method has the potential to be used as a portable microfluidic viscometer for real-time rheological studies. (C) 2020 Elsevier B.V. All rights reserved.

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

Thermoresponsive hydrogels are three-dimensional polymer networks which undergo conformational changes in aqueous media depending on the external temperature. As the lower critical temperature (LCST) is close to the body temperature, poly(N-isopropylacrylamide) (PNIPAM) is the main thermoresponsive hydrogel used for biomedical applications. Below LCST, PNIPAM hydrogels swell in aqueous media, above LCST they become insoluble and shrink. This behavior makes it possible to design drug release systems controlled by external temperature. Swelling/shrinking response of PNIPAM hydrogel depends on several factors such as crosslinker type, crosslinking density, hydrophobic/hydrophilic balance and initiator type. In this study, the effects of the initiation system and the crosslinker type on different thermoresponsive hydrogels were compared. For this purpose, thermoresponsive hydrogels were synthesized by using ethylene glycol dimethylacrylate (EGDMA) and N,N′-ethylene bisacrylamide (EBAM) as crosslinkers via photo and thermal initiation systems. The hydrogels were characterized by scanning electron microscope (SEM) and FTIR spectroscopy. Effects of the initiation system and the crosslinker type on the release, swelling behavior, morphology and the biocompatibility behavior of the hydrogels were investigated. The hydrogels synthesized with EBAM demonstrated more promising results compared to the one synthesized EGDMA. It was concluded that poly(EBAM-co-NIPAM)-P has the highest swelling ratio and poly(EBAM-co-NIPAM)-T is the most biocompatible hydrogel. In terms of release characteristics, there was not a significant difference between the hydrogels, even though their swelling characteristics differ.

BACKGROUND: Measurement of abnormal Red Blood Cell (RBC) deformability is a main indicator of Sickle Cell Anemia (SCA) and requires standardized quantification methods. Ektacytometry is commonly used to estimate the fraction of Sickled Cells (SCs) by measuring the deformability of RBCs from laser diffraction patterns under varying shear stress. In addition to estimations from model comparisons, use of maximum Elongation Index differences (ΔEImax) at different laser intensity levels was recently proposed for the estimation of SC fractions. OBJECTIVE: Implement a convolutional neural network to accurately estimate rigid-cell fraction and RBC concentration from laser diffraction patterns without using a theoretical model and eliminating the ektacytometer dependency for deformability measurements. METHODS: RBCs were collected from control patients. Rigid-cell fraction experiments were performed using varying concentrations of glutaraldehyde. Serial dilutions were used for varying the concentration of RBC. A convolutional neural network was constructed using Python and TensorFlow. RESULTS and CONCLUSIONS: Measurements and model predictions show that a linear relationship between ΔEImax and rigid-cell fraction exists only for rigid-cell fractions less than 0.2. The proposed neural network architecture can be used successfully for both RBC concentration and rigid-cell fraction estimations without a need for a theoretical model.

Identifying a hypercoagulable state in patients with COVID-19 may help identify those at risk for virus–induced thromboembolic events and improve clinical outcomes using personalized therapeutic approaches. Herein, we aimed to perform a global assessment of the patients’ hemostatic system with COVID-19 using rotational thromboelastometry (ROTEM) and to describe whether patients with different disease severities present different coagulation profiles. Together with 37 healthy volunteers, a total of 65 patients were included and then classified as having mild, moderate, and severe disease depending on clinical severity. Peripheral blood samples were collected and analyzed using a ROTEM Coagulation Analyzer. Also, complete blood count and coagulation parameters including prothrombin time, activated partial thromboplastin time, fibrinogen levels, and D-dimer levels were measured at admission. EXTEM and INTEM MCF (P < 0.001) values were significantly higher and the EXTEM CFT (P = 0.002) value was significantly lower in patients with COVID-19 when compared with controls. In particular, patients with the severe disease showed a significant decrease in CFT (P < 0.001) and an increase in MCF (P < 0.001) in both INTEM and EXTEM assays compared with patients with the non-severe disease. Correlation analysis revealed significant correlations between ROTEM parameters and other coagulation parameters. There were significant positive correlations between fibrinogen, D-dimer, platelet count, and MCF in both EXTEM and INTEM assays. Our data demonstrate thromboelastographic signs of hypercoagulability in patients with COVID-19, which is more pronounced in patients with increased disease severity. Therefore, ROTEM analysis can classify subsets of patients with COVID-19 at significant thrombotic risk and assist in clinical decisions., NA

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.

Biyouyumlu hidrojeller, doku iskeleleri, ilaç taşıyıcı sitemler ve biyosensörler dahil olmak üzere çeşitli biyomedikal uygulamalarda kullanılmaktadırlar. Biyomedikal uygulamaların sayısı ve biyomalzemelere olan ihtiyaç arttıkça hidrojel sentezinde kullanılacak yeni ve işlevsel monomerlere olan talep artmaktadır. Çalışmanın amacı, yenilenebilir malzemelerden özgün hidrojeller geliştirmektir. Yenilenebilir malzeme olarak bitkisel yağ bazlı bir monomer olan akrillenmiş metil risinoleat kullanılmıştır. Akrillenmiş metil risinoleat / N-izopropil akrilamid mol oranının hidrojellerin yapısal özellikleri, termal dayanıklılıkları ve in vitro sitotoksisiteleri üzerindeki etkileri incelenmiştir. Hidrojellerin yapısal özelliklerini karakterize etmek için FTIR spektroskopisi kullanılırken, termal özellikleri karakterize etmek için TGA kullanılmıştır. HEK293 ve Cos-7 hücre hatları, monomerlerin ve hidrojellerin sitotoksisitesini test etmek için kullanılmıştır. Akrillenmiş metil risinoleat ve N-izopropil akrilamid için IC50 değerlerinin 25 mg/mL'den büyük olduğu bulunmuştur. %50 veya daha fazla akrillenmiş metil risinoleat içeren hidrojellerin hücre canlılığı %60'ın üzerinde iken, hidrojellerin biyouyumluluğu, akrillenmiş metil risinoleatın hidrojel içerisindeki mol oranı azaldıkça azalmaktadır. Hücreler, hidrojellerin bozunma ürünlerinde inkübe edildiklerinde minimum %80 canlılık göstermiştir. Sonuç olarak, çevre dostu bir sentez yöntemi geliştirilmiş olup, biyomedikal uygulamalarda kullanılmak üzere yenilenebilir malzemelerden özgün biyouyumlu hidrojeller üretilmiştir., Biocompatible hydrogels are used in a variety of biomedical applications, including tissue scaffolds, drug delivery systems, lab/organ-on-a-chips, biosensors, cell-culture studies and contact lenses. The demand for novel and functional monomers to be used in hydrogel synthesis is increasing as the number of biomedical applications and need for biomaterials increase. The purpose of the study was to develop novel hydrogels from renewable materials. Acrylated methyl ricinoleate, a plant oil-based monomer, was used as the renewable material. The effects of acrylated methyl ricinoleate/N-isopropyl acrylamide molar ratio on hydrogel structural properties, thermal stability and in vitro cytotoxicity were studied. FTIR spectroscopy was used to characterize the structural properties of the hydrogels, while TGA was used to characterize the thermal properties. HEK293 and Cos-7 cell lines were used to test the cytotoxicity of the monomers and hydrogels. IC50 values for acrylated methyl ricinoleate and N-isopropyl acrylamide were found to be greater than 25 mg/mL. Cell viability of hydrogels containing 50% or more acrylated methyl ricinoleate was greater than 60%, while hydrogel biocompatibility decreased with decreasing molar ratio of acrylated methyl ricinoleate. Cells showed a minimum viability of 80% when incubated in hydrogel degradation products. An environmentally friendly synthesis method was developed and novel biocompatible hydrogels from renewable materials were produced for biomedical applications.

Amaç: Ani işitme kaybının (AİK) patofizyolojisi hakkında yeterli bilgi olmamakla birlikte,çeşitli yayınlarda, koklear kan akımında azalma, perilenfada oksijenlenmenin azalması gibinedenler bildirilmiştir. Bu nedenle, ilaç tedavisinin yanında sıklıkla hiperbarik oksijen tedavisi(HBOT) de uygulanmaktadır. Ancak, bu tedavinin sonunda, çoğunlukla işitme geri gelse de bazenkulak çınlamasının devam etmesi, bu hastalarda koklear kan akımını etkileyen başka faktörlerinolabileceğini düşündürmektedir. Bu çalışmada, AİK sendromu ile kan akımı faktörlerininilişkisini araştırmak amacı ile bu hastaların hemoreolojik parametreleri incelenmiştir.Gereç ve Yöntem: Bu çalışmaya 14 AİK hastası (yaş: 49.3 ± 12.5) ve diğer bölümlerden 15normal işitmeli gönüllü (yaş: 46.8 ± 11.1) katılmıştır. Kan ve plazma viskoziteleri, koni / düzlemviskozimetresi (Wells-Brookfield) kullanılarak ölçülmüştür. Eritrosit deformabilite (ED) veagregasyon (EA) parametreleri ise lazer uyumlu bir Ektasitometre (LO®RCA, Mechatronics)ile ölçülmüştür. İstatistiksel analizler, Student-t ve Mann-Whitney U testleri kullanılarakyapılmıştır.Bulgular: İki grup arasında yapılan analizlerde, agregasyon sonuçları arasındaki farklar (hasta/kontrol) plazmada: amplitüd [AMP (au)]: 25.49/28.38 (p

To evaluate clotting dynamics by a new tool called rotational tromboelastometry (ROTEM) in retinal vein occlusion.Thirty-six patients who were diagnosed with retinal vein occlusion and 43 age and sex matched healthy controls were included in this study. Diabetes and use of anticoagulant therapy were exclusion criteria. All study participants underwent detailed ophthalmologic and systemic medical examination, including blood pressure measurement, hemoglobin-hematocrit levels, platelet count, coagulation parameters including prothrombin time, activated partial thromboplastin time, fibrinogen levels, and D-dimer levels. Peripheral blood samples were collected and analyzed with ROTEM Coagulation Analyzer (Tem International, Munich, Germany).The RVO patients and controls did not differ with respect to age, sex, hemoglobin, hematocrit, platelet numbers, prothrombin time, activated partial thromboplastin time, fibrinogen levels, D-dimer levels, and glucose levels. When extrinsic thromboelastometry results were analyzed, RVO patients showed a significantly decreased clotting time (76.5 ± 15.0 vs. 95.0 ± 21 s, respectively; p = 0.01) and clot formation time (83.3 ± 22 vs. 99.7 ± 24s; p = 0.01) as compared with healthy controls. Other ROTEM parameters did now show any difference between two groups.Patients with retinal vein occlusion showed faster clotting time and shorter clotting formation time as compared with healthy controls. ROTEM detects the altered clotting dynamics and may be a useful tool to elucidate the disease pathophysiology. Further studies are needed to investigate if it can be used as a screening test for individuals who are under risk to develop RVO or as a first step test to evaluate hypercoagulable state in RVO.

Adaptation to hypoxia requires compensatory mechanisms that affect O2transport and utilization. Decreased hemoglobin (Hb) O2affinity is considered part of the physiological adaptive process to chronic hypoxia. However, this study explores the hypothesis that increased Hb O2affinity can complement acute physiological responses to hypoxia by increasing O2uptake and delivery compared with normal Hb O2affinity during acute severe hypoxia. To test this hypothesis, Hb O2affinity in mice was increased by oral administration of 2-hydroxy-6-{[(2 S)-1-(pyridine-3-carbonyl)piperidin-2yl] methoxy}benzaldehyde (GBT1118; 70 or 140 mg/kg). Systemic and microcirculatory hemodynamics and oxygenation parameters were studied during hypoxia in awake-instrumented mice. GBT1118 increased Hb O2affinity and decreased the Po2at which 50% of Hb is saturated with O2(P50) from 43 ± 1.1 to 18.3 ± 0.9 mmHg (70 mg/kg) and 7.7 ± 0.2 mmHg (140 mg/kg). In a dose-dependent fashion, GBT1118 increased arterial O2saturation by 16% (70 mg/kg) and 40% (140 mg/kg) relative to the control group during 5% O2hypoxia. In addition, a GBT1118-induced increase in Hb O2affinity reduced hypoxia-induced hypotension compared with the control group. Moreover, microvascular blood flow was higher during hypoxia in GBT1118-treated groups than the control group. The increased O2saturation and improved blood flow in GBT1118-treated groups preserved higher interstitial tissue Po2than in the control group during 5% O2hypoxia. In conclusion, increased Hb O2affinity enhanced physiological tolerance to hypoxia, as evidenced by improved hemodynamics and tissue oxygenation. Therefore, pharmacologically induced increases in Hb O2affinity become a potential therapeutic approach to improve tissue oxygenation in pulmonary diseases characterized by severe hypoxemia.NEW & NOTEWORTHY This study establishes that pharmacological modification of hemoglobin O2affinity can be a promising and novel therapeutic strategy for the treatment of hypoxic hypoxia and paves the way for the clinical development of molecules that prevent hypoxemia.

BACKGROUND Erythrocyte deformability is impaired in sickle cell disease (SCD). The regulation of cytoskeletal protein organization plays a key role in erythrocyte deformability. The activation of adenylyl cyclase (AC)/cAMP/Protein kinase A (PKA) signaling pathway was associated with increased deformability in healthy erythrocytes, however the role of this pathway in SCD is unknown. OBJECTIVE We evaluated mechanical responses of sickle red blood cells under physiological levels of shear stress and the possible link between their deformability and AC/cAMP/PKA signaling pathway. METHODS The shearing of sickle red blood cells at physiological level (5 Pa) and the measurement of deformability were performed by a laser assisted optical rotational cell analyzer (LORRCA). RESULTS Red blood cell deformability increased of 2.5-6.5% by blocking the activity of phosphodiesterase with Pentoxifylline (10μM) (p

The mechanical properties and deformability of Red Blood Cells (RBCs) are important determinants of blood rheology and microvascular hemodynamics. The objective of this study is to quantify the mechanical properties and wall shear stress experienced by the RBC membrane during capillary plug flow in vivo utilizing high speed video recording from intravital microscopy, biomechanical modeling, and computational methods. Capillaries were imaged in the rat cremaster muscle pre- and post-RBC transfusion of stored RBCs for 2-weeks. RBC membrane contours were extracted utilizing image processing and parametrized. RBC parameterizations were used to determine updated deformation gradient and Lagrangian Green strain tensors for each point along the parametrization and for each frame during plug flow. The updated Lagrangian Green strain and Displacement Gradient tensors were numerically fit to the Navier-Lame equations along the parameterized boundary to determined Lame's constants. Mechanical properties and wall shear stress were determined before and transfusion, were grouped in three populations of erythrocytes: native cells (NC) or circulating cells before transfusion, and two distinct population of cells after transfusion with stored cells (SC1 and SC2). The distinction, between the heterogeneous populations of cells present after the transfusion, SC1 and SC2, was obtained through principle component analysis (PCA) of the mechanical properties along the membrane. Cells with the first two principle components within 3 standard deviations of the mean, were labeled as SC1, and those with the first two principle components greater than 3 standard deviations from the mean were labeled as SC2. The calculated shear modulus average was 1.1 +/- 0.2, 0.90 +/- 0.15, and 12 +/- 8 MPa for NC, SC1, and SC2, respectively. The calculated young's modulus average was 3.3 +/- 0.6, 2.6 +/- 0.4, and 32 +/- 20 MPa for NC, SC1, and SC2, respectively. o our knowledge, the methods presented here are the first estimation of the erythrocyte mechanical properties and shear stress in vivo during capillary plug flow. In summary, the methods introduced in this study may provide a new avenue of investigation of erythrocyte mechanics in the context of hematologic conditions that adversely affect erythrocyte mechanical properties., Heart Lung and Blood Institute, NIH Grants

Objectives A continuous-flow centrifugal blood pump system has been recently developed as an implantable left ventricular assist device for patients with endstage heart failure. The objective of this study was to evaluate the initial in vivo performance of a newly developed left ventricular assist device (iHeart or Istanbul heart; Manufacturing and Automation Research Center, Koc University, Istanbul, Turkey) in an acute setting using a pig model. Materials and methods Three pigs (77, 83, 92 kg) received implants via a median sternotomy, with animals supported for up to 6 hours. An outflow cannula was anastomosed to the ascending aorta. Anticoagulation was applied by intravenous heparin administration. During the support period, pump performance was evaluated under several flow and operating conditions. All pigs were humanely sacrificied after the experiments, and organs were examined macroscopically and histopathologically. Results Flow rate ranged between 1.5 and 3.6 L/min with pump speeds of 1500 to 2800 revolutions/min and motor current of 0.6 to 1.3 A. Initial findings confirmed thatthe iHeart ventricular assist device had sufficient hydraulic performance to support the circulation. During the experimental period, plasma free hemoglobin levels were found to be within normalranges.Thrombus formation was not observed inside the pump in all experiments. Conclusions The iHeart ventricular assist device demonstrated encouraging hemodynamic performance and good biocompatibility in the pig model for use as an implantable left ventricular assist device. Further acute in vivo studies will evaluate the short-term pump performance prior to chronic studies for long-term evaluation.

Acclimatization to hypoxia or high altitude involves physiological adaptation processes, to influence oxygen (O2) transport and utilization. Several natural products, including aromatic aldehydes and isothiocyanates stabilize the R-state of hemoglobin (Hb), increasing Hb-O2 affinity and Hb-O2 saturation. These products are a counter intuitive therapeutic strategy to increase O2 delivery during hypoxia. 5-Hydroxymethylfurfural (5-HMF) is well known Amadori compound formed during the Maillard reaction (the non-enzymatic browning and caramelization of carbohydrate-containing foods after thermal treatment), with well documented effects in Hb-O2 affinity. This study explores the therapeutic potential of 5-HMF on left ventricular (LV) cardiac function (LVCF) during hypoxia. Anesthetized Golden Syrian hamsters received 5-HMF i.v., at 100 mg/kg and were subjected to stepwise increased hypoxia (15, 10, and 5%) every 30 min. LVCF was assessed using a closed chest method with a miniaturized conductance catheter via continuous LV pressure-volume (PV) measurements. Heart hypoxic areas were studied using pimonidazole staining. 5-HMF improved cardiac indices, including stroke volume (SV), cardiac output (CO), ejection fraction (EF), and stroke work (SW) compared to the vehicle group. At 5% O2, SV, CO, EF, and SW were increased by 53, 42, 33, and 51% with 5-HMF relative to vehicle. Heart chronotropic activity was not statistically changed, suggesting that differences in LV-CF during hypoxia by 5-HMF were driven by volume dependent effects. Analysis of coronary blood flow and cardiac muscle metabolism suggest no direct pharmacological effects from 5-HMF, therefore these results can be attributed to 5-HMF-dependent increase in Hb-O2 affinity. These studies establish that naturally occurring aromatic aldehydes, such as 5-HMF, produce modification of hemoglobin oxygen affinity with promising therapeutic potential to increase O2 delivery during hypoxic hypoxia., National Institutes of Health (NIH); Heart Lung and Blood Institute (HLBI)

Anthracycline chemotherapy (e.g., doxorubicin or DOX) is associated with a cumulative dose-dependent cardiac dysfunction that may lead to congestive heart failure, which limits both its use and usefulness in the clinic. The cardiotoxicity may manifest acutely and/or months or years after treatment with doxorubicin has ended. Experimental and human data have demonstrated that angiotensin-converting enzyme/angiotensin-receptor antagonists mediate a cardioprotective effect against anthracycline toxicity. In this study, with the angiotensin receptor blocker, candesartan, as a positive control, we evaluated whether pretreatment with the hypoxic nitric oxide generating anticancer agent, RRx-001, could reduce acute DOX-induced cardiotoxicity. A total of 24 BALB/c mice were randomized for prophylactic treatment with vehicle, RRx-001, candesartan, or no-intervention control. Within each of the three intervention arms, mice received treatment with DOX. Murine pressure-volume analysis was performed with microconductance catheters to characterize the degree of cardiovascular dysfunction within each group. The following hemodynamic parameters were monitored: left ventricular systolic pressure (LVSP), heart rate, and maximal rate of increase of left ventricular pressure (±d P/d tmax). Five days after doxorubicin injection, untreated (with RRx-001) mice displayed significantly impaired systolic (LVSP, -27%; d P/d tmax, -25%; left ventricular developed pressure (LVDP), +33%; P < 0.05) and global (stroke volume (SV), -52%; ejection fraction (EF), -20%; stroke work (SW), -62.5%; heart rate (HR), -18%; cardiac output (CO), -57%; mean blood arterial pressure (MAP), -30%; systemic vascular resistance (SVR), +20%; P < 0.05) LV functions when compared with the untreated (with RRx-001) group. In contrast, RRx-001-treated mice showed improved variables of systolic (LVSP, +27%; d P/d tmax, +25%; LVDP, -33%; P < 0.05) and global (SV, +52%; EF, +20%; SW, +62.5%; HR, +18%; CO, +57%; MAP, +30%; SVR, -20%; P < 0.05) LV functions compared with untreated doxorubicin mice. Similar to the positive control, candesartan, the cardiotoxic effects of DOX in mice were partially attenuated by the prophylactic administration of RRx-001. These results suggest that RRx-001 as a multifunctional anticancer agent, which sensitizes cancer cells to the cytotoxic effects of chemotherapy and radiation, may also have beneficial cardioprotective effects.

Red blood cells (RBCs) from sickle cell patients exposed to a low oxygen tension reveal highly heterogeneous cell morphologies due to the polymerization of sickle hemoglobin (HbS). We show that angle‐resolved light scattering approach with the use of image‐based flow cytometry provides reliable quantitative data to define the change in morphology of large populations of RBCs from sickle cell patients when the cells are exposed for different times to low oxygen. We characterize the RBC morphological profile by means of a set of morphological and physical parameters, which includes cell shape, size, and orientation. These parameters define the cell as discocyte, sickle, elongated, as well as irregularly or abnormal RBC shaped cells, including echinocytes, holly‐leaf, and granular structures. In contrast to microscopy, quick assessment of large numbers of cells provides statistically relevant information of the dynamic process of RBC sickling in time. The use of this approach facilitates the understanding of the processes that define the propensity of sickle blood samples to change their shape, and the ensuing vaso‐occlusive events in the circulation of the patients. Moreover, it assists in the evaluation of treatments that include the use of anti‐sickling agents, gene therapy‐based hemoglobin modifications, as well as other approaches to improve the quality of life of sickle cell patients. © 2019 International Society for Advancement of Cytometry Alexander von Humboldt Foundation IEEE Antennas and Propagation Society (AP‐S) Doctoral Research Grant

Objective Hemorrhage is the leading cause of injury-related prehospital mortality. We investigated worst-case scenarios and possible requirements of the Turkish military. As we plan to use blood resources during casualty transport, the impact of transport-related mechanical stress on packed red blood cells (PRBCs) was analyzed. Materials and methods The in vitro experiment was performed in the environmental test laboratories of ASELSAN®. Operational vibrations of potential casualty transport mediums such as Sikorsky helicopters, Kirpi® armored vehicles, and the NATO vibration standard MIL-STD-810G software program were recorded. The most powerful mechanical stress, which was created by the NATO standard, was applied to 15 units of fresh (≤7 days) and 10 units of old (>7 days) PRBCs in a blood cooler box. The vibrations were simulated with a TDS v895 Medium-Force Shaker Device. On-site blood samples were analyzed at 0, 6, and 24 h for biochemical and biomechanical analyses. Results The mean (±standard deviation) age of fresh and old PRBCs was 4.9±2.2 and 32.8±11.8 days, respectively. Six-hour mechanical damage of fresh PRBCs was demonstrated by increased erythrocyte fragmentation rates (p=0.015), hemolysis rates (p=0.003), and supernatant potassium levels (p=0.003) and decreased hematocrit levels (p=0.015). Old PRBC hemolysis rates (p=0.015), supernatant potassium levels (p=0.015), and supernatant hemoglobin (p=0.015) were increased and hematocrit levels were decreased (p=0.015) within 6 h. Two (13%) units of fresh PRBCs and none of the old PRBCs were eligible for transfusion after 6 h of mechanical stress. Conclusion When an austere combat environment was simulated for 24 h, fresh and old PRBC hemolysis rates were above the quality criteria. Currently, the technology to overcome this mechanical damage does not seem to exist. In light of the above data, a new national project is being performed.

New Findings What is the central question of this study? The aim was to evaluate the effect of perfusion pressure on blood flow in small arterioles. The hypothesis was that blood flow regulates the thickness of the red-cell-free layer and, therefore, blood flow determines blood apparent viscosity and local vascular resistance in vascular networks with limited myogenic or metabolic regulation of blood flow. What is the main finding and its importance? Reduced perfusion pressures lowered volumetric flow rates and increased local vascular resistance, due to increased blood apparent viscosity. Thus, the local vascular resistance of small arterioles with limited myogenic or metabolic regulation of blood flow, appeared to be determined by changes in blood rheology rather than blood vessel diameter. The study of blood flow regulation is important to understand and resolve pathological conditions. As blood is a complex non-Newtonian multiphase system, the foundations of blood rheological properties have been obtained mostly in viscometers. However, blood rheological behaviour in vivo depends on the concentration of red blood cells (RBCs), their mechanical properties and the RBC hydrodynamics, including RBC migration away from the vessel wall in shear flow. This migration promotes the formation of a RBC-depleted zone, or cell-free layer (CFL), which reduces the apparent viscosity of blood. We hypothesize that perfusion pressure determines blood apparent viscosity in microvessels, as shear rate affects axial migration of RBCs by influencing the CFL thickness. In this study, we analysed the effects of perfusion pressure on blood flow in individual arterioles within the rat cremaster muscle preparation. Perfusion pressures to this microvascular bed were controlled by occlusions of the iliac artery using a pressure cuff. Blood flow measurements were obtained from direct measurements of blood flow velocity profile, as well as determination of CFL thickness using intravital microscopy. Our results indicate that perfusion pressure determines shear rates and the CFL thickness and its variations. In addition, blood flow reduction increased local vascular resistance by augmenting blood apparent viscosity rather than vascular hindrance. In conclusion, blood rheology could act as an intrinsic mechanism to further limit blood flow to tissue with limited myogenic and metabolic responses at low perfusion pressures.

The aim of this work was to analyze a shrouded impeller pediatric ventricular assist device (SIP-VAD). This device has distinctive design characteristics and parameter optimizations for minimization of recirculation flow and reduction in high-stress regions that cause blood damage. Computational Fluid Dynamics (CFD) simulations were performed to analyze the optimized design. The bench-top prototype of SIP-VAD was manufactured with biocompatible stainless steel. A study on the hydrodynamic and hemodynamic performance of the SIP-VAD was conducted with predictions from CFD and actual experimentation values, and these results were compared. The CFD analysis yielded a pressure range of 29–90 mmHg corresponding to flow rates of 0.5–3 L/min over 9000–11000 rpm. The predicted value of the normalized index of hemolysis (NIH) was 0.0048 g/100 L. The experimental results with the bench-top prototype showed a pressure rise of 30–105 mmHg for the flow speed of 8000–12000 rpm and flow rate of 0.5–3.5 L/min. The maximum difference between CFD and experimental results was 4 mmHg pressure. In addition, the blood test showed the average NIH level of 0.00674 g/100 L. The results show the feasibility of shrouded impeller design of axial-flow pump for manufacturing the prototype for further animal trials.

International audience; OBJECTIVES:To investigate the associations between several sickle cell disease genetic modifiers (beta-globin haplotypes, alpha-thalassemia, and glucose-6-phosphate dehydrogenase deficiency) and the level of oxidative stress and to evaluate the association between oxidative stress and the rates of vaso-occlusive events.STUDY DESIGN:Steady-state oxidative and nitrosative stress markers, biological variables, genetic modulators, and vaso-occlusive crisis events requiring emergency admissions were measured during a 2-year period in 62 children with sickle cell anemia (58 SS and 4 Sβ0). Twelve ethnic-matched children without sickle cell anemia also participated as healthy controls (AA) for oxidative and nitrosative stress level measurement.RESULTS:Oxidative and nitrosative stress were greater in patients with sickle cell anemia compared with control patients, but the rate of vaso-occlusive crisis events in sickle cell anemia was not associated with the level of oxidative stress. The presence of alpha-thalassemia, but not glucose-6-phosphate dehydrogenase deficiency or beta-globin haplotype, modulated the level of oxidative stress in children with sickle cell anemia.CONCLUSION:Mild hemolysis in children with alpha-thalassemia may limit oxidative stress and could explain the protective role of alpha-thalassemia in hemolysis-related sickle cell complications.

BACKGROUND: Previous studies have demonstrated that red blood cells (RBC) either lyse or at least experience mechanical damage following prolonged exposure to high shear stress (=100 Pa). Conversely, prolonged shear stress exposure within the physiological range (5-20 Pa, 300 s) was recently reported to improve RBC deformability. This study investigated the relationships between shear stress and RBC deformability to determine the breakpoint between beneficial vs. detrimental exposure to shear stress (i.e., "subhemolytic threshold"). A second aim of the study was to determine whether the frequency of intermittent application of shear stress influenced the subhemolytic threshold. METHODS: RBC were exposed to various levels of shear stress (0-100 Pa) in a Couette type shearing system for 300 s. RBC deformability was then immediately measured via ektacytometry. Parallel experiments were conducted at the same shear stresses, except the application time differed while keeping constant the total exposure time: shear stress was applied either for 30 s and repeated 10 times (10׳0 s) or applied for 15 s and repeated 20 times (20ױ5 s). RESULTS: For a range of donors, the subhemolytic threshold with constant shear stress application was between 30-40 Pa. When physiological shear stress was applied in an intermittent manner, more frequent applications tended to improve (i.e., increase) RBC deformability. However, when supra-physiological shear stress was applied, both continuous and intermittent protocols damaged RBC. Changes of RBC mechanical behavior occurred without increases of hemoglobin in the suspending media, thus attesting to the absence of hemolysis. CONCLUSION: Shear stress has a biphasic effect on the mechanical properties of RBC, with the duration and rate of exposure appearing to have minimal impact on the subhemolytic threshold when compared with the magnitude of applied shear stress.

The microcirculation presents functional organic structures in the range of 1-100 micrometers, commensurate with the upper end of nanotechnology constructs. When devices are designed and deployed to deliver treatment via the circulation they ultimately contend with the smallest dimensions of both healthy and impaired microvessels, particularly the capillary system whose ability to sustain the tissue is assessed by measuring "functional capillary density" (FCD). FCD is directly determined by hydrostatic and osmotic pressures and indirectly by the effect of cardiovascular regulators, particularly the bioavailability of nitric oxide (NO) resulting from fluid mechanical effects and transport in the submicroscopic cell free plasma layer (CFL) located between blood and microvascular wall. Macromolecules using colloids as templates that are surface decorated with polyethylene glycol (PEG) become immuno-invisible and can be introduced into the circulation to manipulate the NO environment in blood and the endothelium. PEG-albumin is a class of molecules with novel plasma expansion properties that directly interacts with the microcirculation via CFL related effects. The principal application of this technology is in transfusion medicine and the plasma expanders used to treat blood losses and concomitant effects on microvascular function due to related acute inflammatory conditions and ischemia.

BACKGROUND: Erythrocytes undergo irreversible morphological and biochemical changes during storage. Reduced levels of deformability have been reported for stored erythrocytes. Erythrocyte deformability is essential for healthy microcirculation. OBJECTIVE: The aim of this study is to evaluate shear stress (SS) induced improvements of erythrocyte deformability in stored blood. METHODS: Deformability changes were evaluated by applying physiological levels of SS (5 and 10 Pa) in metabolically depleted blood for 48 hours and stored blood for 35 days with citrate phosphate dextrose adenine-1 (CPDA-1). Laser diffractometry was used to measure erythrocyte deformability before and after application of SS. RESULTS: Erythrocyte deformability, as a response to continuous SS, was significantly improved in metabolically depleted blood, whereas it was significantly impaired in the blood stored for 35 days with CPDA-1 (p, Scientific and Technological Research Council of Turkey (TÜBİTAK)