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Human Red Blood Cells (human + red_blood_cell)
Selected AbstractsHuman red blood cells have an enhancing effect on the relative expansion of CD8+ T lymphocytes in vitroCELL PROLIFERATION, Issue 6 2001B. Porto The present study was designed to analyse the effect of red blood cells on T-cell proliferation and expansion. A comparative study was done in peripheral blood cell cultures stimulated with phytohemagglutinin, with or without red blood cells. The presence of red blood cells had a consistent enhancing effect on T lymphocyte proliferation, as determined by an increase in both the mitotic index and thymidine uptake. Phenotypic characterization of T cell blasts by flow cytometry revealed that, in the presence of red blood cells, expanding cells were preferentially CD8+ cells. Accordingly, proliferation of CD8+ lymphocytes from two patients with CD8+ hyperlymphocytosis was dependent on the presence of red blood cells. In contrast, proliferation of CD4+ lymphocytes from two patients with CD4+ hyperlymphocytosis was strongly inhibited by the presence of red blood cells. This is the first reported evidence that human red blood cells have an enhancing effect on the expansion of CD8+ lymphocytes in vitro. [source] Cholesterol-rich membrane coatings for interaction studies in capillary electrophoresis: Application to red blood cell lipid extractsELECTROPHORESIS, Issue 20 2006Maria V. Lindén Abstract The purpose was to develop a stable biological membrane coating for CE useful for membrane interaction studies. The effect of cholesterol (chol) on the stability of dipalmitoylphosphatidylcholine (DPPC) and sphingomyelin (SM) coatings was studied. In addition, a fused-silica capillary for CE was coated with human red blood cell (RBC) ghost lipids. Liposomes prepared of DPPC/SM with and without chol or RBC ghost lipids were flushed through the capillary and the stability of the coating was measured electrophoretically. Similar mixtures of DPPC/SM with and without chol were further studied by differential scanning calorimetry. The presence of phosphatidylcholine as a basic component in the coating solution of DPPC/SM/chol was found to be essential to achieve a good and stable coating. The results also confirmed the stability of coatings obtained with solutions of DPPC with 0,30,mol% of chol and SM in different ratios, which more closely resemble natural membranes. Finally, the electrophoretic measurements revealed that a stable coating is formed when capillaries are coated with liposomes of RBC ghost lipids. [source] Effects of clotrimazole on transport mediated by multidrug resistance associated protein 1 (MRP1) in human erythrocytes and tumour cellsFEBS JOURNAL, Issue 24 2001Antonios Klokouzas Clotrimazole has been shown to have potent anti-malarial activity in vitro, one possible mechanism being inhibition of oxidized glutathione (GSSG) export from the infected human red blood cells or from the parasite itself. Efflux of GSSG from normal erythrocytes is mediated by a high affinity glutathione S-conjugate transporter. This paper shows that transport of the model substrate, 3 µm dinitrophenyl S -glutathione, across erythrocyte membranes is inhibited by multidrug resistance-associated protein 1 (MRP1)-specific antibody, QCRL-3, strongly suggesting that the high affinity transport is mediated by MRP1. The rates of transport observed with membrane vesicles prepared from erythrocytes or from multidrug resistant tumour cells show a similar pattern of responses to applied reduced glutathione, GSSG and MRP1 inhibitors (indomethacin, MK571) further supporting the conclusion that the high affinity transporter is MRP1. In both erythrocytes and MRP1-expressing tumour cells, MRP1-associated transport is inhibited by clotrimazole over the range 2,20 µm, and the inhibitory effect leads to increases in accumulation of MRP1 substrates, vincristine and calcein, and decreases in calcein efflux from intact MRP1-expressing human tumour cells. It also results in increased sensitivity to daunorubicin of the multidrug resistant cells, L23/R but not the sensitive parent L23/P cells. These results demonstrate that clotrimazole can inhibit the MRP1 which is present in human erythrocytes, an effect that may contribute to, though not fully account for, its anti-malarial action. [source] Antibacterial and Hemolytic Activities of Quaternary Pyridinium Functionalized PolynorbornenesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 5 2008Tarik Eren Abstract In this study, amphiphilic polyoxanorbornene with different quaternary alkyl pyridinium side chains were synthesized. The biological efficiencies of these polymers, with various alkyl substituents, were determined by bacterial growth inhibition assays and hemolytic activity (HC50) against human red blood cells (RBCs) to provide selectivity of these polymers for bacterial over mammalian cells. A series of polymers with different alkyl substituents (ethyl, butyl, hexyl, octyl, decyl and phenylethyl) and two different molecular weights (3 and 10 kDa) were prepared. The impact of alkyl chain length divided the biological activity into two different cases: those with an alkyl substituent containing four or fewer carbons had a minimum inhibitory concentration (MIC) of 200 µg,·,mL,1 and a HC50 greater than 1,650 µg,·,mL,1, while those with six or more carbons had lower MICs,,,12.5 µg,·,mL,1 and HC50,,,250 µg,·,mL,1. Using MSI-78, the potent Magainin derivative which has an MIC,=,12.0 µg,·,mL,1 and HC50,=,120 µg,·,mL,1, as a comparison, the polymers with alkyl substituents ,C4 (four carbons) were not very potent, but did show selectivity values greater than or equal to MSI-78. In contrast, those with alkyl substituents ,C6 were as potent, or more potent, than MSI-78 and in three specific cases demonstrated selectivity values similar to, or better than, MSI-78. To understand if these polymers were membrane active, polymer induced lipid membrane disruption activities were evaluated by dye leakage experiments. Lipid composition and polymer hydrophobicity were found to be important factors for dye release. [source] Dysprosium-bearing red cells as potential transverse relaxation agents for MRIMAGNETIC RESONANCE IN MEDICINE, Issue 5 2001Kevin M. Johnson Abstract The cytosol of intact human red blood cells was loaded with 28.1 ± 3.4 mM of dysprosium DTPA-BMA using a hypoosmotic technique. When loaded cells were diluted with saline and control cells to give an average dysprosium concentration of 3.3 ± 0.5 mM, the transverse relaxation rate constants R and R2 increased. R increased from 7.5 ± 0.9 sec,1 to 356 ± 50 sec,1, and R2 increased from 7.4 ± 0.7 sec,1 to 148 ± 40 sec,1. After lysing, R was 6.0 ± 0.6 sec,1 in the control and 13.4 ± 1.5 sec,1 in the mixture; R2 was 6.4 ± 1.1 sec,1 and 9.8 ± 2.4 sec,1, respectively. Thus, the relaxivity effects were enhanced by sequestration of the dysprosium within intact red cells, and this effect was lost after lysis. At a circulating whole-blood concentration of 0.81 ± 0.15 mM in rats, the liver signal intensity dropped 29.9% ± 3.7% and kidney signal intensity dropped 19.4% ± 8.7%. Dysprosium-loaded cells might be useful in the study of perfusion and tissue blood volume. Magn Reson Med 45:920,923, 2001. © 2001 Wiley-Liss, Inc. [source] Saturation transfer in human red blood cells with normal and unstable hemoglobin,NMR IN BIOMEDICINE, Issue 1 2003Masaru Sogami Abstract Saturation transfer phenomena from irradiated protein protons to observed water protons in packed human red blood cells (RBCs) with normal or unstable hemoglobin (Hb), i.e. Hb Yokohama and Hb Koeln, were studied using intermolecular cross-relaxation rates [CR; 1/TIS(H2O)], action spectra {[1 ,(I,/I0)] vs f2 (ppm), where I0 and I, are the longitudinal magnetization of observed water protons before and after long-time f2 -irradiation, respectively}, CR spectra [CR vs f2 (ppm)] and CR ratio vs f2 (ppm) with f2 -irradiation from ,100 to 100,ppm at ,H2/2, of 69 or 250,Hz. RBCs (Hb Yokohama) exhibited many large Heinz bodies and strongly impaired filterability, while RBCs (Hb Koeln) showed few microscopically typical Heinz bodies and virtually normal filterability. However, increases in CR values for RBCs (Hb Koeln) and RBCs (Hb Yokohama), monitored by f2 -irradiation below ,,6 and above ,14,ppm, clearly indicated marked increases in association or aggregation of unstable Hb in RBCs compared with those in normal RBCs. CR values, monitored between ,0 and ,10,ppm, were related to not only association or aggregation of unstable Hb but also amounts of water in RBCs. Aggregation or association of unstable Hb exhibited greater effects on CR values compared with those of methemoglobin formation. Copyright © 2003 John Wiley & Sons, Ltd. [source] Multiple three-dimensional mammalian cell aggregates formed away from solid substrata in ultrasound standing wavesBIOTECHNOLOGY PROGRESS, Issue 3 2009Larisa A. Kuznetsova Abstract Single and multiple three-dimensional cell aggregates of human red blood cells (RBCs) and HepG2 cells were formed rapidly in low mega-Hertz ultrasound standing wave fields of different geometries. A single discoid aggregate was formed in a half-wavelength pathlength resonator at a cell concentration sufficient to produce a 3D structure. Multiple cell aggregates were formed on the axis of a cylindrical resonator with a plane transducer (discoid aggregates); in a resonator with a tubular transducer and in the cross-fields of plane and tubular transducers and two plane orthogonal transducers (all cylindrical aggregates). Mechanically strong RBC aggregates were obtained by crosslinking with wheat germ agglutinin (WGA, a lectin). Scanning electron microscopy showed aggregate surface porous structures when RBCs were mixed with WGA before sonication and tighter packing when ultrasonically preformed aggregates were subsequently exposed to a flow containing WGA. HepG2 cell aggregates showed strong accumulation of F-actin at sites of cell,cell contact consistent with increased mechanical stability. The aggregates had a porous surface, and yet confocal microscopy revealed a tight packing of cells in the aggregate's inner core. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Toxicity of a trivalent organic arsenic compound, dimethylarsinous glutathione in a rat liver cell line (TRL 1215)BRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2006T Sakurai Background and purpose: Although inorganic arsenite (AsIII) is toxic in humans, it has recently emerged as an effective chemotherapeutic agent for acute promyelocytic leukemia (APL). In humans and most animals, AsIII is enzymatically methylated in the liver to weakly toxic dimethylarsinic acid (DMAsV) that is a major pentavalent methylarsenic metabolite. Recent reports have indicated that trivalent methylarsenicals are produced through methylation of AsIII and participate in arsenic poisoning. Trivalent methylarsenicals may be generated as arsenical,glutathione conjugates, such as dimethylarsinous glutathione (DMAsIIIG), during the methylation process. However, less information is available on the cytotoxicity of DMAsIIIG. Experimental approach: We synthesized and purified DMAsIIIG using high performance TLC (HPTLC) methods and measured its cytotoxicity in rat liver cell line (TRL 1215 cells). Key results: DMAsIIIG was highly cytotoxic in TRL 1215 cells with a LC50 of 160 nM. We also found that DMAsIIIG molecule itself was not transported efficiently into the cells and was not cytotoxic; however it readily became strongly cytotoxic by dissociating into trivalent dimethylarsenicals and glutathione (GSH). The addition of GSH in micromolar physiological concentrations prevented the breakdown of DMAsIIIG, and the DMAsIIIG-induced cytotoxicity. Physiological concentrations of normal human serum (HS), human serum albumin (HSA), and human red blood cells (HRBC) also reduced both the cytotoxicity and cellular arsenic uptake induced by exposure to DMAsIIIG. Conclusions and implications: These findings suggest that the significant cytotoxicity induced by DMAsIIIG may not be seen in healthy humans, even if DMAsIIIG is formed in the body from AsIII. British Journal of Pharmacology (2006) 149, 888,897. doi:10.1038/sj.bjp.0706899 [source] Protective effects of N-acetyl- L -cysteine against acute carbon tetrachloride hepatotoxicity in ratsCELL BIOCHEMISTRY AND FUNCTION, Issue 1 2008Yu. Z. Maksimchik Abstract In recent years, N-acetyl- L -cysteine (NAC) has been widely investigated as a potentially useful protective and antioxidative agent to be applied in many pathological states. The aim of the present work was further evaluation of the mechanisms of the NAC protective effect under carbon tetrachloride-induced acute liver injuries in rats. The rat treatment with CCl4 (4,g/kg, intragastrically) caused pronounced hepatolysis observed as an increase in blood plasma bilirubin levels and hepatic enzyme activities, which agreed with numerous previous observations. The rat intoxication was accompanied by an enhancement of membrane lipid peroxidation (1.4-fold) and protein oxidative damage (protein carbonyl group and mixed protein-glutathione disulphide formations) in the rat liver. The levels of nitric oxide in blood plasma and liver tissue significantly increased (5.3- and 1.5-fold, respectively) as blood plasma triacylglycerols decreased (1.6-fold). The NAC administration to control and intoxicated animals (three times at doses of 150,mg/kg) elevated low-molecular-weight thiols in the liver. The NAC administration under CCl4 -induced intoxication prevented oxidative damage of liver cells, decreased membrane lipid peroxidation, protein carbonyls and mixed protein-glutathione disulphides formation, and partially normalized plasma triacylglycerols. At the same time the NAC treatment of intoxicated animals did not produce a marked decrease of the elevated levels of blood plasma ALT and AST activities and bilirubin. The in vitro exposure of human red blood cells to NAC increased the cellular low-molecular-weight thiol levels and retarded tert -butylhydroperoxide-induced cellular thiol depletion and membrane lipid peroxidation as well as effectively inhibited hypochlorous acid-induced erythrocyte lysis. Thus, NAC can replenish non-protein cellular thiols and protect membrane lipids and proteins due to its direct radical-scavenging properties, but it did not attenuate hepatotoxicity in the acute rat CCl4 -intoxication model. Copyright © 2007 John Wiley & Sons, Ltd. [source] Human red blood cells have an enhancing effect on the relative expansion of CD8+ T lymphocytes in vitroCELL PROLIFERATION, Issue 6 2001B. Porto The present study was designed to analyse the effect of red blood cells on T-cell proliferation and expansion. A comparative study was done in peripheral blood cell cultures stimulated with phytohemagglutinin, with or without red blood cells. The presence of red blood cells had a consistent enhancing effect on T lymphocyte proliferation, as determined by an increase in both the mitotic index and thymidine uptake. Phenotypic characterization of T cell blasts by flow cytometry revealed that, in the presence of red blood cells, expanding cells were preferentially CD8+ cells. Accordingly, proliferation of CD8+ lymphocytes from two patients with CD8+ hyperlymphocytosis was dependent on the presence of red blood cells. In contrast, proliferation of CD4+ lymphocytes from two patients with CD4+ hyperlymphocytosis was strongly inhibited by the presence of red blood cells. This is the first reported evidence that human red blood cells have an enhancing effect on the expansion of CD8+ lymphocytes in vitro. [source] Protective Effects of Resveratrol and its Analogues against Free Radical-Induced Oxidative Hemolysis of Red Blood Cells,CHINESE JOURNAL OF CHEMISTRY, Issue 11 2002Jian-Guo Fang Abstract The in vitro oxidative hemolysis of human red blood cells (RBCs) was used as a model to study the free radical-induced damage of biological membranes and the protective effect of resveratrol (3,5,4,-trihydroxy-trans-stilbene, 1) and its analogues, i. e., 4-hydroxy- trans -stilbene (2), 3, 5- dihydroxytrans -stilbene (3), 3,4-dihydroxy- trans -stilbene (4), 4,4,-dihydroxy- trans -stilbene (5) and 2, 4, 4,-trihydroxy- trans -stilbene (6). The hemolysis of RBCs was induced by a water-soluble free radical initiator 2, 2,-azobis (2-amidinopropane hydrochloride) (AAPH). It was found that addition of AAPH at 37 °C to the suspension of RBCs caused fast hemolysis after a short period of inhibition period, and addition of 1,6 significantly suppressed the hemolysis. Compound 4 which bears an ortho -dihydroxyl functionality showed much more effective anti-hemolysis activity than that of resveratrol and the other analogues. [source] | ||||||||||||||||