Erythrocyte Membrane Research Papers - Academia.edu (original) (raw)

To determine whether supplementation with the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) affects behavioral symptoms and cognitive impairments in children 6-12 years of age diagnosed with attention-deficit/hyperactivity disorder (ADHD). The randomized, double-blind placebo-controlled 16 weeks trial was conducted with 95 children diagnosed with ADHD according to DSM-IV criteria. Behavior was assessed by parents, teachers and investigators using standardized rating scales and questionnaires. Further outcome variables were working memory, speed of information processing and various measures of attention. For a subgroup of 81 participants, erythrocyte membrane fatty acid composition was analyzed before and after the intervention. Supplementation with the omega-3 fatty acid mix increased EPA and DHA concentrations in erythrocyte membranes and improved working memory function, but had no effect on other cognitive measures and paren...

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- Cognition, Attention, Medicine, Child Behavior

We have devised an analytical method for the determination of fatty acid composition of erythrocyte membrane sphingomyelin by chemical ionization mass spectrometry combined with capillary column gas-liquid chromatography. Fatty acid composition of erythrocyte membrane sphingomyelin from 8 patients with adrenoleukodystrophy (ALD) and 16 healthy controls were exam-

- by Toshio Ariga
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- Chemistry, Neurochemistry, Fatty acids, Sphingomyelin
- by Stephen Koury
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- Membrane Proteins, Cellular, Neuropeptides, Cellular Physiology

Blood doping represents one main trend in doping strategies. Blood doping refers to the practice of boosting the number of red blood cells (RBCs) in the bloodstream in order to enhance athletic performance, by means of blood transfusions, administration of erythropoiesis-stimulating substances, blood substitutes, natural or artificial altitude facilities, and innovative gene therapies. While detection of recombinant EPO and homologous transfusion is already feasible through electrophoretic, mass spectrometry or flow cytometry-based approaches, no method is currently available to tackle doping strategies relying on autologous transfusions. We exploited an in vitro model of autologous transfusion through a 1:10 dilution of concentrated RBCs after 30 days of storage upon appropriate dilution in freshly withdrawn RBCs from the same donor. Western blot towards membrane Prdx2 and Percoll density gradients were exploited to assess their suitability as biomarkers of transfusion. Membrane Pr...

- by Angelo D'Alessandro
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- Biological markers, Erythrocyte Membrane, Erythrocytes, Doping in Sports

The distribution of blood-group A and B determinants was studied by isolating blood-group ABH-active polyglycosyl peptides from delipidated human blood-group AB erythrocyte membranes after extensive digestion with pronase followed by chromatography on Bandeiraea simplicifolia I (BsI) lectin coupled to Sepharose. 20% of the polyglycosyl peptides were bound to BsI lectin. The glycopeptides bound were further fractionated using the blood-group-A-specific lectin from Vicia cracca (Vc). Approximately half of these were bound to the Vc lectin. The glycopeptides, which were bound to the Vc column, were not bound to the blood-group-B-specific isolectin from B. simplicifolia (BsIB4) whereas the Vc-unbound glycopeptides readily bound. The results indicate that in the polyglycosyl peptides isolated from AB erythrocytes A and B determinants are located in different carbohydrate chains. The polyglycosyl peptides, which did not bind to BsI lectin, were composed on the average of 30 monosaccharide units and those that bound contained on the average 55 monosaccharide units. The sugar composition was similar in both fractions except that N-acetylgalactosamine was found only in the BsI-bound glycopeptides. The substitution patterns of the monosaccharides were quite similar in both fractions except 2,3-O-linked galactose, which was enriched 7.5-fold in the BsI-bound glycopeptides and 3,6-O-linked galactose, which also enriched in the BsI-bound glycopeptides suggesting that these have a more branched structure than the BsI-unbound glycopeptides. Glycopeptides derived from bands 3 and 4.5 were prepared from A1B-blood-group erythrocyte membranes and fractionated as above. 25% of the glycopeptides were bound to BsI-lectin from both samples. 70% of the BsI-bound material from band 3 was bound to Vc lectin and 60% from band 4.5. The results indicate heterogeneity in the glycosylation of these bands.

- by Jukka Finne
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- Affinity chromatography, Molecular weight, Erythrocyte Membrane, Erythrocytes

could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise. Objectives: To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n-3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses. Methods: Twelve healthy and regularly trained horses were divided randomly into 2 groups: group S received an oral antioxidant cocktail enriched in n-3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) whereas group P was placebotreated. At the end of 4 weeks, all horses performed a standardised exercise test (ET) under field conditions. Venous blood was sampled before starting treatment (T0), immediately before (T1) as well as 15 mins (T2) and 24 h (T3) after ET. Spin labelled (16-DOXYL-stearic acid) red blood cell membranes were characterised using the relaxation correlation time (Tc in inverse proportion to EMF). Fatty acid composition (%) of the membrane was determined by gas-liquid chromatography. Results: Supplementation (group S) did not induce changes in EMF (T1 vs. T0) but significant changes in membrane composition were observed and there were increases in n-3 polyunsaturated fatty acid PUFA, n-3/n-6 ratio, and total n-3 fatty acids. Exercise (T2 vs. T1) induced a significant decrease of EMF in group P (Tc: +19%, P<0.05) and nonsignificant decrease in group S (Tc: +5%), whereas membrane fatty acid composition did not change in either group. During the recovery period (T3 vs. T2), EMF decreased significantly in group S (Tc: +29%, P<0.05) and nonsignificantly in group P (Tc: +18%) without any significant changes in fatty acid composition. Conclusion and potential relevance: An enriched oral antioxidant supplementation induced changes in membrane composition, which modulated the decrease in EMF induced by exercise. Long chain n-3 fatty acid supplementation might therefore be beneficial.

- by P. Lekeux and +1
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- Biological Sciences, Antioxidants, Fatty acids, Omega-3 fatty acids

This pilot study of ethyl-eicosapentaenoate (ethyl-EPA) in the treatment of Alzheimer's disease aimed to estimate the magnitude of any change in measures of cognition during a 12-week treatment period. A simple linear design was used in which each patient had a baseline period of 12 weeks without treatment, followed by 12 weeks' treatment with ethyl-EPA. Blood samples were taken both before and after the treatment period to measure erythrocyte membrane fatty acids. Assessments comprised cognitive measures and visual analogue ratings of overall assessment of functioning.

- by Crispin Bennett
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- Cognition, Fatty acids, Blood sampling, Clinical Sciences
- by Aurora Cerasi
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- Dialysis, Drug delivery, Macrophages, Drug Delivery Systems

The phospholipid organization in monkey erythrocytes upon Plasmodium knowlesi infection has been studied. Parasitized and nonparasitized erythrocytes from malaria-infected blood were separated and pure erythrocyte membranes from parasitized cells were isolated using Affi-Gei beads. In this way, the phospholipid content and composition of (i) the membrane of nonparasitized cells, (ii) the erythrocyte membrane of parasitized cells and (iii) the parasite could be determined. The phospholipid content and composition of the erythrocyte membranes of nonparasitized and parasitized cells and erythrocytes from chloroquine-treated monkeys cured from malaria, were the same as in normal erythrocytes. The phnspholipid content of the parasite increased during its development, but its composition remained unchanged. Three independent techniques, i.e., treatment of intact cells with phospholipase A 2 and sphingomyelinase C, fluorescamine labeling of aminophospholipids and a phosphatidylcholine-transfer protein-mediated exchange procedure have been applied to assess the disposition of phnspholipids in: (i) erythrocytes from healthy monkeys, (ii) nonparasitized and parasitized erythrocytes from monkeys infected with Plasmodium knowlesi, and (iii) erythrocytes from monkeys that had been cured from malaria by chloroquine treatment. The results obtained by these experiments do not show any abnormality in phospholipid asymmetry in the erythrocyte from malaria-infected (splenectomized) monkeys, neither in the nonparasitized cells, nor in the parasitized cells at any stage of parasite development. Nevertheless, a considerable degree of lipid bilayer destabilization in the membrane of the parasitized cells is apparent from the enhanced exchangeability of the PC from those cells, as well as from their increased permeability towards fluorescamine.

- by H. Vial
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- Chemical Engineering, Malaria, Phospholipids, Plasmodium

The bphospholipid hypothesisQ attributes a pathophysiologic role to the polyunsaturated fatty acid (PUFA) composition of phospholipids in depression. The aim of the present study was to determine whether the hypothesis is relevant to social anxiety disorder (SAD). The study sample consisted of 27 untreated, nondepressed patients with SAD (DSM-IV) and 22 controls. Severity of SAD was assessed with the Liebowitz Social Anxiety Scale (LSAS). Erythrocyte PUFA concentrations were measured by gas-liquid chromatography. Concentrations of most n-3 PUFAs were lower in the patients: 18 : 3n-3 by 32% (p b 0.002), 20 : 3n-3 by 34%, 20 : 5n-3 by 36% (all p b 0.001) and 22 : 6n-3 by 18% (p = 0.002). No significant differences were observed in other fatty acids. Significant inverse correlations were obtained between levels of n-3 PUFAs and LSAS scores. In conclusion, the phospholipid hypothesis may apply to SAD, thereby opening new therapeutic options. The robust relationship between low erythrocyte n-3 PUFA concentrations and SAD justifies exploration of relevant neuropathophysiological mechanisms.

- by Sofi Marom
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- Fatty acids, Omega-3 fatty acids, Regression Analysis, European

The malaria parasite Plasmodium falciparum infects human erythrocytes, and it induces an increased rate of uptake into the infected cell of a range of solutes, including essential nutrients required for parasite development. Several models have been proposed for the mechanism(s) underlying parasite-induced solute uptake, each differing with respect to the site of entry into infected cells. We show that a biotin derivative that is excluded from non-infected erythrocytes gains access to infected erythrocytes via a pathway that is inhibited by compounds shown previously to block the pathways responsible for the increased uptake of solutes. The derivative was found to bind erythrocyte cytoskeletal proteins and to hemoglobin, providing evidence that the novel pathways are in the erythrocyte membrane and allow direct access of solutes to the erythrocyte cytosol. The derivative inhibited its own uptake and blocked the parasite-induced transport of other solutes. In whole-cell patch-clamp analyses, biotinylation of infected erythrocytes caused significant decrease in a parasite-induced outward rectifying conductance. In vitro, biotinylation of trophozoite-stage parasitized erythrocytes delayed parasite development. Treatment of infected cells in the final developmental stage abrogated the parasite's ability to complete development. The data are consistent with the novel pathways playing an important role in parasite growth.

- by Stefan Baumeister
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- Patch-clamp and imaging techniques, Biological Sciences, Molecular, Biotin
- by Narcisa Bandarra
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- Nutrition, Obesity, Multidisciplinary, Hunger

Plasma membrane permeabilization by saponin and anticancer avicins was studied using light dispersion measurements, since high correlation between light dispersion changes and hemolysis has been demonstrated. Nevertheless, we observed that rat red blood cell swelling in moderately hypotonic media was accompanied by up to 20% decrease of light dispersion, when hemolysis was not yet detectable. Avicin G and avicin D were significantly more efficient than saponin in inducing cytotoxicity in PC3 human prostate cancer cells. We found that the preincubation of avicins with the plasma membrane, but not with the cytosolic fraction of previously lysed red blood cells, completely protected fresh cells against permeabilization. The data suggest that the plasma membrane can tightly bind the avicins, but not the saponin. Using the "osmotic protection" method with 100 mOsm PEGs of increasing molecular weight in isotonic media, the size of the pores generated by avicin G and avicin D in the plasma membrane was estimated to be higher than the hydrodynamic radius of PEG-8000. The obtained results indicate that the anticancer activity of avicin G and avicin D could be related, at least partially, to their high ability to permeabilize biological membranes. These data might represent interest for possible applications of these anticancer drugs in vivo.

- by victor jairo
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- Chemical Engineering, Prostate Cancer, Saponins, Biological Sciences

A~t~ct-Affinity, specificity and kinetics for [3H]-DHA binding to human red cell ghost were determined by ultra-filtration. At 2" an apparent dissociation constant of 0.96 nM was found with maximum specific binding of 29 fmoles per mg protein. The low dissociation constant was confirmed by kinetic studies with a value of 0.86 nM. Propranolol and isoproterenol inhibited t3H]-DHA binding stereospecifically. Agonist potency (IPR > EPI > NE) indicated that human erythrocytes had an adtenergic receptor of be&z-2 subtype. Isoproterenol in the presence of theophylline resulted in a concentrationdependent increase of intracellular CAMP levels in intact cells. Basal and maximal levels were 2.3 and 7.5 pmoles/lOa cells respectively after 2.5 min stimulation. Et& for isoproterenol was 0.27 PM. Propranolol shifted the isoproterenol concentration response curve to the right. The present results show that human erythrocytes possess recognition sites for beta-adrenergic ligands with binding characteristics similar to that of adrenergic receptors of beta-2 subtype. At least a small number of these binding sites are functionally coupled to adenylate cyclase.

- by Georg Sager
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- Kinetics, cyclic AMP, Radioligand Assay, BIOCHEMICAL PHARMACOLOGY

If we compare aquaporin (as a proteic pathway for water permeation across biological membranes) with a child we can say that he had a very long gestation period. His possible existence was predicted for a long time (Overton in 1985, Stein and, some of his features (transport of water and its reversible inhibition) were assigned by Macey and Farmer in 1970, however this child was first detected by Benga and coworkers in 1986. We clearly demonstrated for the first time the presence and location of a water channel at the human RBC membrane among the polypeptides migrating in the region having 35-60 kDa on the electrophoretogram of RBC membranes, labeled with 203 Hg-PCMBS in the conditions of specific inhibition of water diffusion; I suggested that a minor membrane protein that binds PCMBS is involved in water transport and also indicated the way in which the specific protein could be further characterized: by purification and reconstitution in liposomes. Our landmark papers in 1986 can be compared with the first detection of a child "in utero" by ultrasonography, since we discovered one of the essential components of the "aquaporin child" (a molecular weight of 35-60 kDa for the glycosylated component); we have also indicated the way to recognize him after birth (among other children of his group!): placing the isolated children in a certain environment and asking them to perform the same task (one should read: reconstitution studies in liposomes and measurement of water permeability), like aligning athletes for a running test. This was the only certain way to know that the child is really the fastest runner and not just one that is helping (by various means) another child to be fastest runner. A "new child" was observed in 1988 by Agre and coworkers, who identified a novel integral membrane protein in human RBCs having a non-glycosylated component of 28 kDa and a glycosylated component migrating as a diffuse band of 35-60 kDa; they suggested that the new protein (nick-named CHIP28 in 1991) may play a role in linkage of the membrane skeleton to the lipid bilayer. In 1992 Agre and coworkers suggested that CHIP28 is a functional unit of membrane water channels; by reconstitution in liposomes it was demonstrated that CHIP28 is a water channel itself rather than a water channel regulator. In other words the child we first detected was recognized as having the predicted qualities only in 1992. In 1993 CHIP28 was renamed aquaporin 1. Looking in retrospect, asking the crucial question, when was the first water channel protein, aquaporin 1, discovered, a fair and clear cut answer would be: the first water channel protein, now called aquaporin 1, was identified or "seen" in situ in the human RBC membrane by Benga and coworkers in 1986. It was again "seen" when it was by chance purified by Agre and coworkers in 1988 and was again identified when its main feature, the water transport property was found by Agre and coworkers in 1992. If a comparison with the discovery of The New World of America is made, the first man who has "seen" a part, very small indeed, of The New Land was Columbus; later, others, including Amerigo Vespucci (from whom the name derived), have better "seen" a larger part of the new Continent and in the subsequent years many explorers discovered the complexity of the Americas! 2003 Published by Elsevier Ltd.

- by Gheorghe Benga
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- Water, Cell Biology, Aquaporins (AQP), Ultrasonography

This work analyzed the effects of the aqueous crude extracts of Artemisia absinthium L., Lippia sp., Bryophyllum sp., Solidago microglossa DC, Cymbopogon citratus DC and Mentha x villosa HUDSON on the osmotic stability of human erythrocytes. Hemolysis was monitored by measurement of absorbance at 540 nm following addition of erythrocytes to NaCl solutions of varying concentration. Absorbance was fitted to sigmoid regression curves given by the Boltzmann equation, and hemolysis was characterized by the NaCl concentration leading to lysis of 50% of cells (H 50 ), and by the intensity (H) and the amplitude (dS) of the lysis effect. The parameters were determined in the absence and presence of the crude extracts. The extracts of Artemisia absinthium, Lippia sp., C. citratus and M. villosa protected human erythrocytes against hypotonic shock, as evidenced by a decrease in the values of H and H 50 compared to the control solution (p < 0.05). The extracts of Bryophyllum sp. and S. microglossa enhanced hemolysis, since their H 50 values were higher than in the control group (p < 0.05), but they also showed protective effects, as evidenced by a decrease in H and an increase in dS.

- by Rita Netto
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- Medicinal Plants, Adolescent, Regression Analysis, Artemisia

The binding of [*03Hg] p(ch1oromercuri)benzenesulfonate to the membrane proteins of human erythrocytes and erythrocyte ghosts was examined under conditions where binding to the bulk of membrane sulfhydryl groups was blocked by N-ethylmaleimide. Binding was essentially complete within 90 min when approximately 40 nmol was bound per milligram of membrane protein. This binding was correlated with the inhibition of water transport measured by an N M R technique. Maximal inhibition was observed with the binding of approximately 10 nmol of p-(chloromercuri)benzenesulfonate/mg of membrane protein. Under these conditions, both band 3 and band 4.5 bound 1 mol of inhibitor/mol of protein. In contrast to previous experiments, these results indicate that band 4.5 proteins as well as band 3 have to be considered as playing a role in water transport.

- by O. Popescu
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- Biochemistry, Thermodynamics, Kinetics, Membrane Proteins

Accidental transfusion of ABO-incompatible red blood cells (RBCs) is a leading cause of fatal transfusion reactions. To prevent this and to create a universal blood supply, the idea of converting blood group A and B antigens to H using specific exo-glycosidases capable of removing the immunodominant sugar residues was pioneered by Goldstein and colleagues at the New York Blood Center in the early 1980s. Conversion of group B RBCs to O was initially carried out with a-galactosidase extracted from coffee beans. These enzyme-converted O (ECO) RBCs appeared to survive normally in all recipients independent of blood group. The clinical trials moved from small infusions to single RBC units and finally multiple and repeated transfusions. A successful phase II trial utilizing recombinant enzyme was reported by Kruskall and colleagues in 2000. Enzymatic conversion of group A RBCs has lagged behind due to lack of appropriate glycosidases and the more complex nature of A antigens. Identification of novel bacterial glycosidases with improved kinetic properties and specificities for the A and B antigens has greatly advanced the field. Conversion of group A RBCs can be achieved with improved glycosidases and the conversion conditions for both A and B antigens optimized to use more cost-efficient quantities of enzymes and gentler conditions including neutral pH and short incubation times at room temperature. Of the different strategies envisioned to create a universal blood supply, the ECO concept is the only one, for which human clinical trials have been performed. This paper discusses some biochemical and clinical aspects of this developing technology.

- by Humberto de la Vega
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- Clinical Trial, Kinetics, Forecasting, Blood groups

The hypothesis that physiologically activeconcentrations of salicylic acid (SA) and itsderivatives can confer stress tolerance in plants wasevaluated using bean (Phaseolus vulgaris L.) andtomato (Lycopersicon esculentum L.). Plantsgrown from seeds imbibed in aqueous solutions (0.1--0.5 mM) of salicylic acid or acetyl salicylic acid(ASA) displayed enhanced tolerance to heat, chillingand drought stresses. Seedlings acquired similarstress tolerance when SA or ASA treatments wereapplied as soil drenches. The fact that seedimbibition with SA or ASA confers stress tolerance inplants is more consistent with a signaling role ofthese molecules, leading to the expression oftolerance rather than a direct effect. Induction ofmultiple stress tolerance in plants by exogenousapplication of SA and its derivatives may have asignificant practical application in agriculture,horticulture and forestry.

- by Darren Touchell
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- Plant Biology, Drought Stress, Stress tolerance, Tomato

Propolis is a resinous substance collected from plants by bees. Its composition depends on the vegetation, the season, and the source area. It usually contains many chemical compounds such as polyphenols, steroids and amino acids.

- by Leticia Estevinho and +1
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- Flavonoids, Propolis, Seasonality, Apis mellifera
- by Faouzi Baklouti
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- British, Membrane Proteins, Neuropeptides, Sequence alignment

The membrane of most eukaryotic cells comprises lipid, cholesterol, and protein molecules. The precise three-dimensional arrangement of the components of a cell membrane imparts its unique functions via several specific molecular interactions. The fluid-mosaic model of Singer and Nicholson gives us a picture of two asymmetric lipid lamellae into which proteins are intercalated to varying extents.l The lipid phase of the membrane is also arranged asymmetrically in the familiar bilayer structure. Basically, the two different types of proteins are classified by Singer and Nicho1son.l integral and peripheral, depending on their ease of isolation from the membrane. Peripheral proteins are generally at the bilayer surface, held (loosely) by electrostatic interactions; integral proteins penetrate the lipid phase of the membrane to varying degrees and frequently traverse the entire bilayer.

- by Lawrence Berliner
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- Chemistry, Membrane Proteins, Multidisciplinary, Protein Conformation

In human and experimental CCl4-1iver damage, S-adenosyl-l-methionine-synthetase and/or the intrahepatic content of Sadenosyl-l-methionine, are diminished and in human cirrhosis phospholipid methyltransferase is markedly reduced. Therefore the aim of this study was to investigate the effect of S-adenosyl-l-methionine administration on liver damage induced by 15-day bile duct ligation. Liver damage was analyzed by histological, ultrastructural and biochemical techniques. Biliary obstruction produced an increase in collagen content, dilation of the bile canaliculi and disorganization of mitochondria. These effects were not observed in the bile-duct-ligated group receiving S-adenosyl-l-methionine. Biochemical results showed that bile duct ligatidn increased serum bilirubins, and alkaline phosphatase and ~-glutamyl transpeptidase activities. These effects were prevented significantly by S-adenosyl-l-methionine. On the other hand, glycogen content in the liver was depleted while lipid peroxidation was increased by biliary obstruction, S-adenosyl-l-methionine administration prevented these effects. In the bile-duct-ligated group, hepatocyte and erythrocyte plasma membrane Na+/K + and Ca2+-ATPases were lower than in the control group (p<0.05). Administration of S-adenosyl-l-methionine preserved ATPase activities. The exogenous S-adenosyl-l-methionine supply is probably responsible for restoring transmethylation lost in liver diseases. © Journal of Hepatology.

- by Pedro Yojcom Gonzalez
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- Hepatology, ATPase, Liver, Lipid peroxidation

The risk of developing multiple sclerosis (MS) is associated with increased dietary intake of saturated fatty acids. For many years it has been suspected that this disease might be associated with an imbalance between unsaturated and saturated fatty acids. We determined erythrocyte membrane fatty acids levels in Hot nature dietary intervention with co-supplemented hemp seed and evening primrose oils in multiple sclerosis patients. To determine the erythrocyte membrane fatty acids levels and correlate it with expanded disability status scale (EDSS) at baseline after 6 months intervention in MS patients by gas chromatography, in this double blind, randomized trial, 100 RRMS patients with EDSS<6 were allocated into three groups: "Group A" that received co-supplemented hemp seed and evening primrose oils with advised Hot nature diet. "Group B" received olive oil and "Group C" received the co-supplemented oils. The results showed that the mean follow-up was 180±2.9SD days (N=65, 23 M and 42 F aged 34.25±8.07 years with disease duration of 6.80±4.33 years). There was no significant difference in the study parameters at baseline. After 6 months, EDSS, Immunological parameters and the erythrocyte cell membrane with regard to specific fatty acids showed improvement in the group A and C, whereas there was worsening condition for the group B after the intervention. We concluded that Hot-nature dietary intervention with co-supplemented hemp seed and evening primrose oils caused an increase PUFAs in MS patients and improvement in the erythrocyte membrane fatty acids composition. This could be an indication of restored plasma stores, and a reflection of disease severity reduction.

- by Mehdi Farhoudi
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- Treatment Outcome, Fatty acids, Dietary Supplements, Gas Chromatography

Background: Among the red cell membrane disorders, hereditary spherocytosis (HS) is one of the most common causes of inherited hemolytic anemia. The aim of this study was to compare the flow-cytometric approach for screening of red cell membrane disorders based on osmotic fragility with the eosin-5-maleimide (E5 0 M) dye test. A group of b-thalassemia heterozygotes were also studied.

Objective Recent observations showed that long chain omega 3 polyunsaturated fatty acids (n-3 LCPUFA) could represent a potential treatment for elderly depression. To determine if a n-3 LCPUFA containing supplement improves depressive symptoms, changes phospholipids acids profile and ameliorates Health related quality of life (HRQoL) in depressed elderly patients. Design Two-months, randomized, double-blind, placebo-controlled trial. Setting Nursing home in Pavia, Italy. Subjects Forty-six depressed

- by Mariangela Rondanelli
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- Engineering, Psychiatry, Autism, Depression
- by Antonella Pantaleo
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- Hematology, Cytoskeleton, Blood, Phosphorylation

Cryohydrocytosis' is an unusual human haemolytic anaemia of the 'hereditary stomatocytosis' group, in which the red cell membrane is abnormally permeable to Na and K + at both body and (even more prominently) refrigerator temperatures. If whole cryohydrocytosis blood is anticoagulated in heparin or EDTA and stored on ice overnight, about 50% of the cells will lyse. Citrate phosphate dextrose adenine (CPDa) anticoagulant, empirically verified as an optimal anticoagulant for storage of normal blood before transfusion, very markedly ameliorated this overnight lysis, suggesting that these cells might form an informative model in which cold storage of the red cell could be studied in a short time scale. Accordingly, we conducted studies of ion flux, cell swelling and lysis in different media used historically for blood preservation and compared the experimental data with an 'integrated red cell model', which seeks mathematically to model the osmotic behaviour of red cells under different conditions. Upon experiment, lysis in these cells was reduced by additives that could be regarded as impermeant extracellular solutes (citrate, mannitol) and by low pH, but not by those agents that are regarded as protecting the cell against energy depletion or oxidation (adenine, glucose, nicotinic acid). The protective effects of these extracellular additives were all reproduced by the computer simulation, confirming the validity of this model, although the effect of pH could be simulated only semiquantitatively, possibly because Na + permeability itself depends on pH.

- by Helen Jarvis
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- Cryopreservation, Computer Simulation, Iron, Storage

Rh (Rhesus) proteins (D, CcEe) are expressed in red cells (RBC) in association with other membrane proteins (RhAG, LW, CD47 and GPB). By interacting with the spectrin-based skeleton through protein 4.2 and ankyrin, the Rh complex contributes to the maintenance of the mechanical properties of the erythrocyte membrane. The RH system is one of the most immunogenic and polymorphic human blood group system. Molecular basis of most Rh phenotypes, including the Rh null phenotype associated with hemolytic anemia, have been determined. The demonstration that the RHD-positive locus is composed of the RHD and RHCE genes, whereas the RHD gene is deleted in most RhD-negative individuals, allowed fetal RhD genotyping by non-invasive PCR assays for antenatal diagnosis of pregnancy at risk for Rh hemolytic disease of the newborn. In mammals, the Rh protein family includes two non-erythroid members, RhBG and RhCG, mainly expressed in liver and kidney, two organs specialized in ammonia genesis and excretion. Functional analyses in heterologous systems revealed that RhAG, RhBG and RhCG can mediate ammonium (NH 3 and/or NH þ 4 ) transport across the cell membrane and might represent mammalian specific ammonium transporters. Furthermore, recent studies performed in human and murine red blood cells (RBC) indicate that RhAG facilitates CH 3 NH 2 /NH 3 movement across the membrane and represents a potential example of gas channel. The crystallographic structure of the bacterial ammonia channel AmtB and functional studies showing that AmtB conducts NH 3 into reconstituted vesicles is fully consistent with these latter studies. In RBCs, RhAG may transport NH 3 to detoxifying organs like kidney and liver and with non-erythroid tissues orthologs may contribute to regulation of the acid-base balance.

- by Jean-pierre Cartron
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- Polymorphism, Protein Structure and Function, Pregnancy, Mice

Background/Aims: The viral integrase enzyme inhibitor dolutegravir is utilized for the treatment of immunodeficiency virus (HIV) infection. Knowledge on cytotoxicity of dolutegravir is limited. The present study thus explored, whether dolutegravir is able to trigger suicidal erythrocyte death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Cellular mechanisms involved in the triggering of eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, ceramide, and activation of protein kinase C, p38 kinase, casein kinase, and caspases. The present study explored, whether Dolutegravir induces eryptosis and, if so, to gain insight into cellular mechanisms involved. Methods: Utilizing flow cytometry, phosphatidylserine exposure at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ROS formation f...

- by Abdulla Bhuyan
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- Flow Cytometry, Calcium, Oxidative Stress, Reactive Oxygen Species

Nitric oxide (NO) plays a fundamental role in maintaining normal vasomotor tone. Recent data implicate a critical function for hemoglobin and the erythrocyte in regulating the activity of NO in the vascular compartment. Intravascular hemolysis releases hemoglobin from the red blood cell into plasma (cell-free plasma hemoglobin), which is then able to scavenge endothelium-derived NO 600-fold faster than erythrocytic hemoglobin, thereby disrupting NO homeostasis. This may lead to vasoconstriction, decreased blood flow, platelet activation, increased endothelin-1 expression (ET-1), and end-organ injury, thus suggesting a novel mechanism of disease for hereditary and acquired hemolytic conditions such as sickle cell disease and cardiopulmonary bypass. Furthermore, therapy with NO gas inhalation or infusion of sodium nitrite during hemolysis may attenuate this disruption in vasomotor balance by oxidizing plasma cell-free hemoglobin, thereby preventing the consumption of endogenous NO and the associated pathophysiological changes. In addition to providing an NO scavenging role in the physiological regulation of NO-dependent vasodilation, hemoglobin and the erythrocyte may deliver NO as the hemoglobin deoxygenates. While this process has previously been ascribed to S-nitrosated hemoglobin, recent data from our laboratories suggest that deoxygenated hemoglobin reduces nitrite to NO and vasodilates the human circulation along the physiological oxygen gradient. This newly described role of hemoglobin as a nitrite reductase is discussed in the context of blood flow regulation, oxygen sensing, and nitrite-based therapeutics.

- by Rakesh Patel
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- Free Radicals, Free Radical, Anoxia, Nitric oxide

We describe the organization of wet-lab special-study modules (SSMs) in the Central Research Laboratory of Dokuz Eylü l Medical School, Izmir, Turkey with the aim of discussing the scientific, laboratory, and pedagogical aspects of this educational activity. A general introduction to the planning and functioning of these SSMs is given, along with specific examples. The wet-lab SSMs incorporate several innovative pedagogies: problem-based learning, research-based learning, practical laboratory education, team-based learning, and project-based learning. Oral and written evaluations show that the students find this activity rewarding. The wet-lab SSM model applied in the Research-Lab of Dokuz Eylü l School of Medicine represents a format which is effective in training the students in research methodology, practical laboratory work, and independent learning.

- by Zahide Cavdar
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- Biochemistry, Research Methodology, Research Design, Molecular Biology
- by john carney
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- Pharmacology, Free Radicals, Membrane Proteins, Western blotting

With the increasing use of artificial organs, blood damage has been raising ever more clinical concern. Blood trauma is in fact a major complication resulting from the implantation of medical devices and the use of life support apparatuses. Red blood cells damage predictive models furnish critical information on both the design and the evaluation of artificial organs, because their correct usage and implementation are thought to provide clear and rational guidance for the improvement of safety and efficacy. The currently adopted power-law shear-induced haemolysis prediction model lacks sensitivity with respect to the cumulative effect of previously applied stress magnitudes. An alternative model is proposed where a mechanical quantity was defined, able to describe the blood damage sustained by red cells under unsteady stress conditions, taking into account the load history. The proposed formulation predicted the same trend as the available experimental data. The obtained results have to be considered a preliminary validation of the basic hypothesis of this modified red blood cell damage prediction model. To date, the necessity to design further experiments to validate the proposed damage function clashes with the limitations inherent to current systems to get the time-varying shear stress completely under control.

- by Mauro Grigioni
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- Mechanical Engineering, Algorithms, Biomedical Engineering, Modeling

The red cell membrane Li+/Na+exchange is a heteroexchange that operates in either direction across the cell membrane. It binds either Li+ or Na+ on one side of the membrane and it exchanges the transported species for either Li+ or Na+ on the opposite side in a stoichiometric ratio of 1:1. In the population, Li+/Na+exchange is unimodally distributed but skewed to the right. Such distribution results from superimposition of two normal distributions. Many laboratories have shown that red-cell Li+/Na+ exchange is increased in patients with essential hypertension, compared with normotensive controls. Among the various alterations of cell membrane cation transport reported in hypertension, the increase of red-cell Li+/Na+ exchange has been most widely investigated and confirmed. Moreover, increased Li+/Na+ exchange has been found in some clinical conditions related to hypertension, such as overweight and diabetes. Among diabetic patients, Li+/Na+ exchange is particularly high in patients...

- by Andrea Semplicini
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- Lithium, Hypertension, Sodium, Erythrocyte Membrane

A role of indices of oxidative stress, oxidative injury, and abnormal membrane phospholipid, specifically the phospholipid essential polyunsaturated fatty acids (EPUFAs) metabolism has been suggested based on studies in separate groups of patients with or without medication. The current study investigated the relationship between these biochemical measures in first-episode psychotic patients (N=16) at baseline and after 6 months of antipsychotic treatment (N=5 each with risperidone and olanzapine) and compared them to matched normal subjects. The indices of oxidative stress included: antioxidant enzymes; superoxide dismutase, glutathione peroxidase and catalase; and the oxidative injury as the levels of plasma lipid peroxides. The key membrane EPUFA's been; linolenic acid, arachidonic acid, nervonic acid, docosapentaenoic acid and docosahexaenoic acid. Furthermore, the changes in these biochemical measures were correlated with clinical symptomatology. Data indicated that, at bas...

- by Vinay Parikh
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- Oxidative Stress, Antioxidants, Omega-3 fatty acids, Catalase

Plant flavonoids are emerging as potent therapeutic drugs effective against a wide range of free radical mediated diseases. Hence their interactions with cell membranes, which generally serve as targets for lipid peroxidation, are of enormous interest. Here we report in vitro studies, via absorption and fluorescence spectroscopy, on the effects of several flavonoids (namely fisetin, quercetin, chrysin, morin, and 3-hydroxyflavone, 3-HF) in goat RBC membranes. Owing to the presence of functionally relevant membrane protein components embedded in the lipid bilayer RBC ghosts provide a more realistic system for exploring drug actions in biomembranes than simpler membrane models like phosphatidylcholine liposomes used in our previous studies [e.g. B. Sengupta, A. Banerjee, P.K. Sengupta, FEBS Lett. 570 ]. Here, we demonstrate that binding of the flavonoids to the RBC membranes significantly inhibits lipid peroxidation, and at the same time enhances their integrity against hypotonic lysis. Interestingly, the antioxidant and antihemolytic activities are found to be crucially dependent on the locations of the flavonoids in the membrane matrix as revealed by fluorescence studies. Furthermore, we observe that FRET (from membrane protein tryptophans to flavonoids) occurs with significant efficiency indicating that the flavonoid binding sites lie in close proximity to the tryptophan residues in the ghost membrane proteins.

- by Bidisa Sengupta and +1
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- Fluorescence Spectroscopy, Membrane Proteins, Flavonoids, Fluorescence Resonance Energy Transfer

The plasma membrane calcium ATPase (PMCA) reaction cycle is associated with conformational changes. Results: We identified different conformations after the association of Ca 2ϩ , ATP, and vanadate to PMCA. Conclusion: PMCA forms a stable complex with Ca 2ϩ and vanadate; ATP can bind to all pump conformations. Significance: This study found a new intermediate in the PMCA reaction cycle; all of the intermediates interact with ATP.

- by Irene Mangialavori and +1
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- Biological Chemistry, Biological Sciences, CHEMICAL SCIENCES, Ion Transport

The occurrence of the Haber-Weiss reaction and other interactions between free radicals has been investigated in the effects of mixtures of free radicals on the permeability of resealed erythrocyte ghosts and on the activity of membrane-bound glyceraldehyde-3-phosphate dehydrogenase. The following mixtures were found to induce damage greater than that which could be accounted for by the independent actions of the constituent free radicals: (i) .OH + H,O*, and (ii) .OH + H,O, + 0;. In contrast, the following mixtures were found to induce less damage than that predicted on the basis of independent actions of constituent free radicals: (i) H,O1 + OF, and (ii) oxidizing radicals ('OH, HzO,) + reducing radicals (e-, H '). These results suggest a Haber-Weiss-like interaction between H,O, and 0; and an interaction between H,O, and 'OH to produce a species more potent than either in causing increased permeability. The decrease in damage observed in the simultaneous presence of oxidizing and reducing radicals suggests an antagonistic effect by which each tends to moderate damage by the other. Inactivation of glyceraldehyde-3-phosphate dehydrogenase was found to be more sensitive to radiation than permeability by an order of magnitude, while permeability was more sensitive to the enhancement of damage by oxygen. Comparison of the effectiveness of free radical scavengers in inhibiting the increase in permeability caused by free radicals showed the following order of effectiveness, expressed in terms of percentage protection: formate (90%) > nitrogen (65%) > catalase (60%) > dismutase (32%), and with respect to enzymatic inactivation, nitrogen (100%) > formate (77%) > dismutase (48%) > catalase (44%). The relative rates observed anaerobically and aerobically in the presence and absence of the above scavengers suggest that (at least in the case of radiation damage to the membranes of erythrocyte ghost cells) the "oxygen effect" is due to the interaction of oxygen with e-and H., producing 0; which aggravates damage under conditions which allow consequent Haber-Weiss-like reactions. The further increase in damage when oxygen concentration is raised yet higher is due to the interaction of oxygen with the sites of initial damage.

- by Allan Davison
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- Free Radicals, Kinetics, Hydrogen Peroxide, Oxygen

Sifuvirtide is a gp41 based peptide that inhibits HIV-1 fusion with the host cells and is currently under clinical trials. Previous studies showed that sifuvirtide partitions preferably to saturated phosphatidylcholine lipid membranes, instead of fluid-phase lipid vesicles. We extended the study to the interaction of the peptide with circulating blood cells, by using the dipole potential sensitive probe di-8-ANEPPS. Sifuvirtide decreased the dipole potential of erythrocyte and lymphocyte membranes in a concentration dependent manner, demonstrating its interaction. Also, the lipid selectivity of the peptide towards more rigid phosphatidylcholines was confirmed based on the dipole potential variations. Overall, the interaction of the peptide with the cell membranes is a contribution of different lipid preferences that presumably directs the peptide towards raft-like domains where the receptors are located, facilitating the reach of the peptide to its molecular target, the gp41 in its pre-fusion conformation.

- by Pedro Matos
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- Clinical Trial, HIV, Lipid Membranes, Peptides
- by Z. Gluvic and +2
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- Yugoslavia, Treatment Outcome, Linear models, Multivariate Analysis

Plasmodium falciparum histidine-rich protein 2 (PfHRP2) has been suggested to be an initiator of the polymerization of heme, which is produced as by-product on the digestion of hemoglobin, and a promoter of the H 2 O 2 -induced degradation of heme in food vacuoles of the malarial parasite. In this work, we have designed PfHRP2 model peptides, R18 and R27 (18 and 27 residues, respectively), and used them for optical and electron spin resonance spectroscopic measurements to confirm that the axial ligands of the heme-PfHRP2 complex are the nitrogenous donors derived from the imidazole moieties of histidine residues of PfHRP2. In addition, we revealed that the affinities of R18 and R27 for heme (K d = 2.21 ´ 10 -6 M and 0.71 ´ 10 -6 M, respectively) might be as high as that of PfHRP2 (K d = 0.94 ´ 10 -6 M). The R27 peptide can remove heme from membrane-intercalated heme and inhibit heme-induced hemolysis. Therefore, we suggest another function of PfHRP2: it may play an important role in the neutralization of toxic heme in the parasite cytoplasm and infected erythrocytes by removing heme from heme-bound membranes or reducing heme-induced hemolysis. tyl. We defined ferric protoporphyrin IX as heme or protoheme, and ferric mesoprotoporphyrin IX as mesoheme.

- by Nguyen Tien Huy
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- Biochemistry, Spectrophotometry, Proteins, Heme

It is a long-standing mystery why erythrocyte actin filaments in the junctional complex (JC) are uniformly ∼37 nm and the membrane skeleton consists of hexagons. We have previously proposed that a “molecular ruler” formed by E-tropomodulin and tropomyosin 5 or 5b functions to generate protofilaments of 12 G actin under mechanical stress. Here, we illustrate that intrinsic properties of actin filaments, e.g., turns, chemical bonds, and dimensions of the helix, also favor fragmentation into protofilaments under mechanical stress. We further construct a mechanical model in that a pair of G actin is wrapped around by a split α and β spectrin, which may spin to two potential positions, and stabilize to one when the tail end is restricted. A reinforced protofilament may function as a mechanical axis to anchor three (top, middle, and bottom) pairs of Sp. Each Sp pair may wrap around the protofilament with a wide dihedral angle (∼166.2°) and a minimal axial distance (2.75 nm). Such three Sp pairs may spiral down (right handed) the protofilament from the pointed end with a dihedral angle of ∼55.4° in between the Sp pairs. This first three-dimensional model of JC may explain the hexagonal geometry of the erythrocyte membrane skeleton. © 2003 Biomedical Engineering Society. PAC2003: 8716Ka, 8716Dg, 8714Ee, 8716Ac

- by Carlos Vera
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- Engineering, Biomedical Engineering, Membrane Proteins, Computer Simulation

The resonance energy transfer from donors embedded in the membrane of erythrocytes to the cytosol hemoglobin has been measured by comparing the donors' fluorescence decay in ghosts and in intact cells. A series of n -(9-anthroyloxy) stearic acids (n-AS) (n = 2, 6, 9, 12) and similar probes were used as donors, and their locations within the outer leaflet of the phospholipid bilayer were determined from their average efficiency of energy transfer, ( T ). The energy transfer data for several membrane probes were analyzed according to a simple semiempirical model, in which the heme acceptors are assumed to form a semiinfinite continuum beyond a plane, whose normal distance (d) from particular donors may be determined if the heme density in the cytosol boundary layer is known. The hemoglobin concentration in the erythrocytes was varied by suspending the cells in buffers of different ionic strengths. This made it possible to study the ionic strength dependence of the heme concentration averaged over the cell (hc), as well as that in the boundary layer (hb). Both level off above approximately 600 mosM, as does the ratio hb/hC. By using the maximum heme concentration that can be obtained in osmotically shrunken cells as a limiting value, hb is estimated to be 17 mM or less, under physiological conditions; and from the measured (T ) for various probes, the distance d was found to range from 40 A for 2-AS to 31 A for 12-AS and 26 A for 9-vinyl anthracene (9-VA). It is concluded that the hydrophobic probe 9-VA is located near the center of the phospholipid bilayer and that the cytosol hemoglobin is in contact with the inner membrane surface, or nearly so. This conclusion is valid for oxy-and deoxy-hemoglobin, and is shown to be independent of several systematic errors that might arise from the simple assumptions of the model used. The steady-state fluorescence anisotropy of the probes was found to decrease as they approach the bilayer's central plane. The methodology developed here may be used to extend studies of cytosol membrane interactions in ghost systems to intact cells, and is useful in the investigation of the morphology of normal and pathological intact erythrocytes.

- by Jorge Flores
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- Mathematics, Biophysical Chemistry, Biological Sciences, Physical sciences

Vegan Vegetarian Biomarkers Omega-3 index Ageing Omega-3 fatty acids s u m m a r y Background & aims: Several studies have demonstrated that vegetarians and vegans have much lower plasma concentrations of omega-3 fatty acids (i.e., docosahexaenoic and eicosapentaenoic acids) when compared to those who eat fish. The purposes of this study were 1) to define the age and/or sex-specific docosahexaenoic plus eicosapentaenoic acids levels in red blood cell membranes (expressed as a percent of total fatty acids; hereafter the omega-3 index) in long-term vegans, and 2) to determine the effects of a vegetarian omega-3 supplement (254 mg docosahexaenoic plus eicosapentaenoic acids/day for 4 months) on the omega-3 index. Methods: A sample (n ¼ 165) of vegans was recruited, and their omega-3 index was determined using a dried blood spot methodology. A subset of 46 subjects with a baseline omega-3 index of <4% was given a vegetarian omega-3 supplement for 4 months and then retested. Results: The mean AE SD omega-3 index was 3.7 AE 1.0% which was similar to that of a cohort of omnivores (deployed US soldiers) from a recently-reported study. Among the vegan cohort, the index was significantly higher in females than males (3.9 AE 1.0% vs. 3.5 AE 1.0%; p ¼ 0.026) and was directly related to age (p for trend ¼ 0.009). The omega-3 index increased from 3.1 AE 0.6% to 4.8 AE 0.8% (p ¼ 0.009) in the supplementation study. Conclusions: We conclude that vegans have low baseline omega-3 levels, but not lower than omnivores who also consume very little docosahexaenoic and eicosapentaenoic acids. The vegans responded robustly to a relatively low dose of a vegetarian omega-3 supplement.

- by Barbara Sarter
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- Nutrition and Dietetics, Biomarkers, Treatment Outcome, Clinical Nutrition

Exposure of cellular membranes to dehydroascorbic acid can result in a loss of membrane integrity. Renal brush border or basolateral membrane vesicles pre-incubated with dehydroascorbic acid demonstrate a decrease in initial transport rates of D-glucose and a loss of intravesicular volume. The activity of brush border membrane specific leucine aminopeptidase is increased in vesiculated membrane preparations following exposure of the vesicles to either dehydroascorbic acid or Triton X-100. Erythrocytes in isotonic buffer with dehydroascorbic acid lose membrane integrity as demonstrated by a release of hemoglobin.

- by Richard Rose
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- Toxicology, Glucose, Rats, Erythrocyte Membrane

Sphingosine, at 5-15 mol % total lipids, remarkably increases the permeability to aqueous solutes of liposomal and erythrocyte ghost membranes. The increased permeability cannot be interpreted in terms of leakage occurring at the early stages of a putative membrane solubilization by sphingosine, nor is it due to a sphingosine-induced generation of nonlamellar structures, or flipflop lipid movement. Instead, sphingosine stabilizes (rigidifies) gel domains in membranes, raising their melting temperatures and increasing the transition cooperativity. Structural defects originating during the lateral phase separation of the ''more rigid'' and ''less rigid'' domains are likely sites for the leakage of aqueous solutes to the extravesicular medium. The presence of coexisting domains in the plasma membrane makes it a target for sphingosine permeabilization. The sphingosine-induced increase in rigidity and breakdown of the plasma membrane permeability barrier could be responsible for some of the physiological effects of sphingosine.

- by Jesús Sot
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- Water, Biophysical Chemistry, Biological Sciences, Differential scanning calorimetry
- by Mats Wahlgren
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- Biology, Malaria, Plasmodium falciparum, Protozoan Proteins