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1

Monitoring of membrane phospholipid scrambling in human erythrocytes and K562 cells with FM1-43 - a comparison with annexin V-FITC

100%
Wrobel A., Bobrowska-Hagerstrand M., Lindqvist C., Hagerstrand H.
Cellular and Molecular Biology Letters
|
2014
|
tom 19
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nr 2
The styryl dye FM1-43 becomes highly fluorescent upon binding to cell membranes. The breakdown of membrane phospholipid asymmetry in ionophore-stimulated T-lymphocytes further increases this fluorescence [Zweifach, 2000]. In this study, the capacity of FM1-43 to monitor membrane phospholipid scrambling was explored using flow cytometry in human erythrocytes and human erythrocyte progenitor K562 cells. The Ca2+-dependent phosphatidylserine-specific probe annexin V-FITC was used for comparison. The presented data show that the loss of phospholipid asymmetry that could be induced in human erythrocytes by elevated intracellular Ca2+ or by structurally different membrane intercalated amphiphilic compounds increases the FM1-43 fluorescence two- to fivefold. The profile of FM1-43 fluorescence for various treatments resembles that of phosphatidylserine exposure reported by annexin V-FITC. FM1-43 detected the onset of scrambling more efficiently than annexin V-FITC. The amphiphile-induced scrambling was shown to be a Ca2+-independent process. Monitoring of scrambling in K562 cells caused by NEM-induced Ca2+-release from intracellular stores and by Ca2+ and ionophore A23187 treatment showed that the increase in FM1-43 fluorescence correlated well with the number of annexin V-FITC-detected phosphatidylserine-positive cells. The results presented here show the usefulness of FM1-43 as a Ca2+-independent marker of dissipation in asymmetric membrane phospholipid distribution induced by various stimuli in both nucleated and non-nucleated cells.
2

Do shape transformations in erythrocytes reflect the flip rate of amphiphilic compounds?

100%
Hagerstrand H., Bobrowska-Hagerstrand M., Isomaa B.
Cellular and Molecular Biology Letters
|
1996
|
tom 01
|
nr 1
It has been shown that the time course of echinocyte to discocyte transformation caused by exogenous phospholipids is an accurate measure of the flip rate of the phospholipids in the lipid bilayer [1,2]. In order to explore whether shape changes in erythrocytes are indicative of flip rates of water- soluble amphiphiles, the time course of shape changes caused by a large number of amphiphiles was studied. In case of amphiphiles inducing echinocyte to discocyte or discocyte to stomatocyte transformation it is proposed that the time course of shape transformation may be indicative of the flip rate of the amphiphiles. The relevance of using shape changes in erythrocytes as a tool to estimate flip rates of amphiphiles is discussed.
3

Erythrocytes vesiculate at high pH

100%
Bobrowska-Hagerstrand M., Iglic A., Hagerstrand H.
Cellular and Molecular Biology Letters
|
1997
|
tom 02
|
nr 1
Human erythrocytes were incubated at alkaline pH. In samples equilibrating within 60 min to pH 11 erythrocytes underwent prelytic vesiculation (fragmentation). Erythrocytes developed large (diameter often 1-2 µm) hemoglobin-filled blebs which could be released to the outer medium as hemoglobin containing vesicles. It is suggested that the described vesiculation at high pH occurs due to an uncoupling of the membrane skeleton from the lipid bilayer. Due to the uncoupling from the skeleton the erythrocyte lipid bilayer may behave similar to the membrane of a giant lipid vesicle.
4

Gemini [dimeric] surfactant perturbation of the human erythrocyte

88%
Dubnickova M., Bobrowska-Hagerstrand M., Soderstrom T., Iglic A., Hagerstrand H.
Acta Biochimica Polonica
|
2000
|
tom 47
|
nr 3
We studied the ability of di-cationic gemini surfactantsdi (amphiphiles), i.e. 1,4-butanediammonium-N,N-dialkyl-N,N,N',N'-tetramethyl bromides (Di-Cm-di-QAS (s = 4), where m = 8,11,13,16 and s = the number of alkyl groups in the spacer) to induce shape alteration, vesiculation, haemolysis and phosphatidylserine exposure in human erythrocytes, and to protect erythrocytes against hypotonic haemolysis. At high sublytic concentrations the Di-Cm-di-QAS (s = 4) amphiphiles rapidly induced echinocytic (spiculated) shapes and a release of exovesicles, mainly in the form of tubes, from the cell surface. Following 60 min incubation erythrocytes were sphero-echinocytic and a few cells with invaginations/endovesicles were observed. No phosphatidylserine exposure was detected. The haemolytic potency increased with an increase of the alkyl chain length. At sublytic concentrations the Di-Cm-di-QAS (s = 4) amphiphiles protected erythrocytes against hypotonic haemolysis. It is suggested that the Di-Cm-di-QAS (s = 4) amphiphiles perturb the membrane in a similar way as single-chain cationic amphiphiles, but that they do not easily translocate to the inner membrane leaflet.
5

Oxyethylene chain-cation complexation; Nonionic polyoxyethylene detergents attain a positive charge and demonstrate electrostatic head group interactions

76%
Hagerstrand H., Bobacka J., Bobrowska-Hagerstrand M., Kralj-Iglic V., Fosnaric M., Iglic A.
Cellular and Molecular Biology Letters
|
2001
|
tom 06
|
nr 2
6

Torocytes - a new class of vesicle shapes

76%
Hagerstrand H., Kralj-Iglic V., Bobrowska-Hagerstrand M., Bialkowska K., Isomaa B., Iglic A.
Cellular and Molecular Biology Letters
|
1998
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tom 03
|
nr 2
Torocyte shaped endovesicles with a low relative volume were induced in human erythrocytes by polyethyleneglycol dodecylether (C12E8). It is suggested that the torocyte endovesicles are formed in a process where an initially stomatocytic invagination loses volume while maintaining its large surface area. The boundaries of the phase diagram of the observed torocytes are described.
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