scholarly journals Trans-stimulation and trans-inhibition of uridine efflux from human erythrocytes by permeant nucleosides

1986 ◽  
Vol 233 (1) ◽  
pp. 295-297 ◽  
Author(s):  
S M Jarvis
Keyword(s):  
Human Erythrocyte ◽  
Maximum Velocity ◽  
Human Erythrocytes ◽  
Lower Maximum

The ability of nucleoside permeants to accelerate the efflux of uridine from human erythrocytes has been compared. In contrast to uridine, 2-chloroadenosine acted as a trans-inhibitor of uridine efflux from fresh human erythrocytes, and adenosine had little effect. These results are consistent with the lower maximum velocity for influx of 2-chloroadenosine and adenosine as compared with uridine and demonstrate that trans acceleration experiments do not discriminate between transported and non-transported permeants for the human erythrocyte nucleoside carrier.

Elemental analysis of human erythrocytes

1989 ◽  
Vol 47 ◽  
pp. 242-243
Author(s):  
S. A. Livesey ◽  
A. A. del Campo ◽  
E. S. Griffey ◽  
D. Ohlmer ◽  
T. Schifani ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Elemental Analysis ◽  
Human Erythrocyte ◽  
Spectroscopic Analysis ◽  
Model System ◽  
Human Erythrocytes ◽  
List Type ◽  
Chemical Fixation ◽  
Ethanol Dehydration ◽  
Lowicryl K4m

The aim of this study is to compare methods of sample preparation for elemental analysis. The model system which is used is the human erythrocyte. Energy dispersive spectroscopic analysis has been previously reported for cryofixed and cryosectioned erythrocytes. Such work represents the reference point for this study. The use of plastic embedded samples for elemental analysis has also been documented. The work which is presented here is based on human erythrocytes which have been either chemically fixed and embedded or cryofixed and subsequently processed by a variety of techniques which culminated in plastic embedded samples.Heparinized and washed erythrocytes were prepared by the following methods for this study :(1). Chemical fixation in 4% paraformaldehyde/0.25% glutaraldehyde/0.2 M sucrose in 0.1 M Na cacodylate, pH 7.3 for 30 min, followed by ethanol dehydration, infiltration and embedding in Lowicryl K4M at -20° C.

Lead and calcium transport in human erythrocyte

1999 ◽  
Vol 18 (5) ◽  
pp. 327-332 ◽  
Author(s):  
J V Calderón-Salinas ◽  
M A Quintanar-Escorcia ◽  
M T González-Martínez ◽  
C E Hernández-Luna
Keyword(s):  
Transport System ◽  
Human Erythrocyte ◽  
Calcium Transport ◽  
Human Erythrocytes ◽  
The Other ◽  
Erythrocyte Ghosts ◽  
Passive Transport ◽  
Ca Uptake

In this paper we report the lead (Pb) and calcium (Ca) uptake by erythrocyte ghosts. In both cases the transport was carried out by a passive transport system with two kinetic components (Michaelis-Menten and Hill). Pb and Ca were capable of inhibiting the transport of the other metal in a non-competitive way. Under hyperpolarization, the uptakes of Ca and Pb were enhanced and the Michaelis-Menten component prevailed. Both Ca and Pb uptakes were inhibited by N-ethyl-maleimide to the same extent. These results indicate that Pb and Ca share the same permeability pathway in human erythrocytes and that this transport system is electrogenic.

scholarly journals A carbohydrate-deficient membrane glycoprotein in human erythrocytes of phenotype S-s-

1977 ◽  
Vol 165 (1) ◽  
pp. 157-161 ◽  
Author(s):  
M J A Tanner ◽  
D J Anstee ◽  
P A Judson
Keyword(s):  
Blood Group ◽  
Arachis Hypogaea ◽  
Human Erythrocyte ◽  
Structure And Function ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Membrane Glycoprotein ◽  
Blood Group Antigens ◽  
And Function ◽  
Normal Erythrocyte

1. We investigated the membranes of human erythrocytes which completely lack the blood-group antigens S and s (denoted as S-s-) as part of a study of the structure and function of the surface glycoproteins of the human erythrocyte. 2. The S-s-erythrocyte-membrane glycoprotein PAS-3 band was much less intensely stained in comparison with that of the glycoprotein from normal erythrocyte membranes. The S-s-membrane glycoprotein PAS-4 band also showed decreased staining. 3. Examination with the lectins from Maclura aurantiaca (Osage orange) and Arachis hypogaea (groundnut) showed that the PAS-3 glycoprotein of S-s-erythrocyte membranes lacked the receptors for these lectins that are present on glycoprotein PAS-3 from normal erythrocytes. 4. Radioiodination with lactoperoxidase showed the presence of the polypeptide of glycoprotein PAS-3 in S-s-cells, although it was more weakly labelled than the protein in the normal erythrocyte. 5. Our results show that the PAS-3 glycoprotein of S-s-erythrocytes is deficient in some of the carbohydrates present in the protein from normal erythrocytes. Glycoprotein PAS-4 of normal erythrocytes is shown to be a complex containing both glycoproteins PAS-1 and PAS-3.

scholarly journals Quantitation of adenosine-5'-triphosphate used for phosphoinositide metabolism in human erythrocytes

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1133-1137 ◽  
Author(s):  
GL Dale
Keyword(s):  
Steady State ◽  
Human Erythrocyte ◽  
Human Erythrocytes ◽  
Phosphoinositide Metabolism ◽  
Quasi Steady State ◽  
Futile Cycle ◽  
Independent Measure

Abstract The human erythrocyte actively phosphorylates and dephosphorylates phosphatidylinositol present in the membrane in an apparent “futile cycle.” Recent reports have proposed that this phosphorylation/dephosphorylation cycle is a significant consumer of adenosine-5′-triphosphate (ATP) in the erythrocyte. This study details two independent techniques for quantitating the ATP consumed by this phosphoinositide futile cycle. With the first technique a quasi-steady- state labeling of erythrocyte ATP with 32P-phosphate was obtained, and the rate of synthesis of 32P-phosphoinositides was then monitored. The second technique used a novel labeling strategy that allowed only ATP to be labeled with 32P; the transfer of 32P from ATP to phosphoinositides was then an independent measure of the ATP consumed for phosphoinositide synthesis. These two techniques documented that 0.5% to 1.0% of net ATP produced by the erythrocyte is used for phosphoinositide synthesis.

Physiological changes in human erythrocyte cholinesterase as measured with the "pH-stat".

1988 ◽  
Vol 34 (10) ◽  
pp. 2133-2135 ◽  
Author(s):  
J A Garcia-López ◽  
M Monteoliva
Keyword(s):  
Human Erythrocyte ◽  
Cholinesterase Activity ◽  
Human Erythrocytes ◽  
Physiological Changes ◽  
Individual Values ◽  
Blood Samples ◽  
Age Related ◽  
Population Average ◽  
Ph Stat ◽  
Stat Method

Abstract Cholinesterase activity in human erythrocytes was determined in 1903 blood samples by the "pH-stat" method. Differences in activity were examined as a function of sex, age, and pregnancy. Reliability intervals for the population average and approval or normality intervals for individual values were established. Sex- and age-related differences were very significant.

scholarly journals Stimulating Effect of Terfenadine on Erythrocyte Cell Membrane Scrambling

2016 ◽  
Vol 38 (4) ◽  
pp. 1425-1434 ◽  
Author(s):  
Elena Signoretto ◽  
Michela Castagna ◽  
Abdulla Al Mamun Bhuyan ◽  
Florian Lang
Keyword(s):  
Cell Membrane ◽  
Human Erythrocyte ◽  
Haemoglobin Concentration ◽  
Annexin V ◽  
Human Erythrocytes ◽  
Forward Scatter ◽  
Erythrocyte Surface ◽  
Suicidal Death ◽  
Phosphatidylserine Translocation ◽  
Surface Signaling

Background/Aims: The antihistaminic drug Terfenadine may trigger apoptosis of tumor cells, an effect unrelated to its effect on histamine receptors. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, the suicidal death of erythrocytes characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling triggering eryptosis include increase of cytosolic Ca2+ activity ([Ca2+]i), oxidative stress, and ceramide. The present study explored, whether Terfenadine is capable to trigger eryptosis. Methods: Flow cytometry was employed to estimate phosphatidylserine abundance at the erythrocyte surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, abundance of reactive oxygen species (ROS) from 2′,7′-dichlorodihydrofluorescein (DCF) diacetate dependent fluorescence, and ceramide abundance at the human erythrocyte surface utilizing specific antibodies. Hemolysis was quantified from haemoglobin concentration in the supernatant. Results: A 48 hours exposure of human erythrocytes to Terfenadine (≥ 5 µM) significantly increased the percentage of annexin-V-binding cells and triggered hemolysis without significantly modifying the average forward scatter. Terfenadine (7.5 µM) significantly increased Fluo3-fluorescence, but did not significantly modify DCF fluorescence or ceramide abundance. The effect of Terfenadine on annexin-V-binding was significantly blunted but not abolished by removal of extracellular Ca2+. Exposure of human erythrocytes to Ca2+ ionophore ionomycin (1 µM, 15 min) triggered annexin-V-binding, an effect augmented by Terfenadine pretreatment (10 µM, 48 hours). Conclusions: Terfenadine triggers phospholipid scrambling of the human erythrocyte cell membrane, an effect in part due to entry of extracellular Ca2+ and in part due to sensitizing human erythrocyte cell membrane scrambling to Ca2+.

THE INFLUENCE OF TRUCKS ON TRAFFIC FLOW — AN INVESTIGATION ON THE NAGEL–SCHRECKENBERG-MODEL

2000 ◽  
Vol 11 (04) ◽  
pp. 837-842 ◽  
Author(s):  
ANJA EBERSBACH ◽  
JOHANNES SCHNEIDER ◽  
INGO MORGENSTERN ◽  
RAINER HAMMWÖHNER
Keyword(s):  
Traffic Flow ◽  
Maximum Velocity ◽  
Time Development ◽  
Basic Properties ◽  
Lower Maximum

A few years ago Nagel and Schreckenberg introduced a model for traffic flow,1 which, though quite simple, is able to reproduce the basic properties of traffic. Meanwhile many variations of the model have been developed, part of them concentrate on introducing an inhomogenous fleet of cars with different maximum velocities. Here we also want to study the effect of introducing a certain fraction of vehicles with a lower maximum velocity ("trucks") to the Nagel–Schreckenberg-model. We give a detailed description of this effect and focus on the time development of the influence of trucks on traffic flow.

The influence of chlorpromazine on the potential-induced shape change of human erythrocyte

1991 ◽  
Vol 11 (4) ◽  
pp. 213-221 ◽  
Author(s):  
J. Hartmann ◽  
R. Glaser
Keyword(s):  
Red Blood Cells ◽  
Human Erythrocyte ◽  
Blood Cells ◽  
Characteristic Time ◽  
Time Course ◽  
Transmembrane Potential ◽  
Shape Change ◽  
Human Erythrocytes

The effect of chlorpromazine (CPZ) on the shape of human erythrocytes with different values of transmembrane potential (TMP) was investigated. The shape of red blood cells with negative values of the TMP remained unchanged after the formation of stomatocytes by chlorpromazine, while cells with positive TMP showed a characteristic time course of shape change during the incubation with CPZ. Experiments with vanadate show that this might be due to a difference in the activity of the phospholipid-translocase at different values of TMP.

scholarly journals Oxidation and enzyme-activated irreversible inhibition of rat liver monoamine oxidase-B by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

1986 ◽  
Vol 240 (2) ◽  
pp. 379-383 ◽  
Author(s):  
K F Tipton ◽  
J M McCrodden ◽  
M B Youdim
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Maximum Velocity ◽  
Monoamine Oxidase B ◽  
Half Time ◽  
Inhibitory Process ◽  
Irreversible Inhibitor ◽  
Irreversible Inhibition ◽  
Km Value ◽  
Lower Maximum

The compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces symptoms resembling Parkinson's disease in humans, acts both as a substrate and an enzyme-activated irreversible inhibitor of the B-form of monoamine oxidase from rat liver. Analysis of the inhibitory process showed the compound to be considerably more efficient as a substrate than as an irreversible inhibitor, with about 17000 mol of product being formed per mol of enzyme inactivated. The half-time of the inhibitory process was about 22 min. With the A-form of the enzyme, the compound had a lower Km value and a considerably lower maximum velocity than the corresponding values obtained with the B-form. Under the conditions used in the present work the inhibition of the A-form of the enzyme was largely reversible.

scholarly journals Analysis of Receptor for Vibrio choleraeEl Tor Hemolysin with a Monoclonal Antibody That Recognizes Glycophorin B of Human Erythrocyte Membrane

1999 ◽  
Vol 67 (10) ◽  
pp. 5332-5337 ◽  
Author(s):  
Dongyan Zhang ◽  
Junko Takahashi ◽  
Taiko Seno ◽  
Yoshihiko Tani ◽  
Takeshi Honda
Keyword(s):  
Monoclonal Antibody ◽  
Vibrio Cholerae ◽  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Mammalian Cells ◽  
Biochemical Characterization ◽  
Human Erythrocytes ◽  
Human Erythrocyte Membrane ◽  
El Tor ◽  
Glycophorin B

ABSTRACT El Tor hemolysin (ETH), a pore-forming toxin secreted byVibrio cholerae O1 biotype El Tor and most Vibrio cholerae non-O1 isolates, is able to lyse erythrocytes and other mammalian cells. To study the receptor for this toxin or the related molecule(s) on erythrocyte, we first isolated a monoclonal antibody, B1, against human erythrocyte membrane, which not only blocks the binding of ETH to human erythrocyte but also inhibits the hemolytic activity of ETH. Biochemical characterization and immunoblotting revealed that this antibody recognized an epitope on the extracellular domain of glycophorin B, a sialoglycoprotein of erythrocyte membrane. Erythrocytes lacking glycophorin B but not glycophorin A were less sensitive to the toxin than were normal human erythrocytes. These results indicate that glycophorin B is a receptor for ETH or at least an associated molecule of the receptor for ETH on human erythrocytes.

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