Lateral organization of mixed, two-phosphatidylcholine liposomes as investigated by GPS, the slope of Laurdan generalized polarization spectra

2007 ◽  
Vol 466 (1) ◽  
pp. 145-154 ◽  
Author(s):  
Alba A. Vallejo ◽  
Jesús B. Velázquez ◽  
Marta S. Fernández
Keyword(s):  
Generalized Polarization ◽  
Phosphatidylcholine Liposomes ◽  
Polarization Spectra ◽  
Lateral Organization

Glycoproteins IIb and IIIa and Platelet Thrombospondin in a Liposome Model of Platelet Aggregation

1986 ◽  
Vol 55 (02) ◽  
pp. 240-245 ◽  
Author(s):  
M E Rybak
Keyword(s):  
Platelet Aggregation ◽  
Direct Evidence ◽  
Phospholipid Vesicles ◽  
Aggregate Formation ◽  
Membrane Glycoproteins ◽  
Protein Orientation ◽  
Phosphatidylcholine Liposomes ◽  
Calcium Dependent ◽  
Lentil Lectin ◽  
Complete Reversal

SummaryPlatelet membrane glycoproteins IIb and IIIa and platelet thrombospondin were incorporated onto phosphatidylcholine liposomes, by freeze thawing and sonication. Protein orientation on the liposomes was confirmed by susceptibility to neuraminidase cleavage and binding to lentil lectin-Sepharose (GPIIb-IIIa liposomes) and to heparin-Sepharose (thrombospondin liposomes). Glycoproteins Ilb-IIIa bound 125I-fibrinogen with Kd of 7.5 × 10™7M. Binding was reversible and calcium-dependent. Ilb-IIIa liposomes underwent fibrinogen-dependent aggregation in the presence of 10 mM CaCl2. Maximal aggregate formation was observed with a combination of IIb-IIIa liposomes and thrombospondin liposomes. This aggregation was partially inhibited by preincubation with monoclonal antibodies to the IIb-IIIa complex. Addition of EDTA caused complete reversal of aggregates. Thrombospondin liposomes also underwent fibrinogen and calcium dependent aggregation, however, this aggregation was less than that observed with the GPIIb-IIIa liposomes. Maximal aggregate formation was observed with a mixture of IIb-IIIa liposomes and thrombospondin liposomes. These studies demonstrate that GPIIb-IIIa and thrombospondin can be incorporated into phospholipid vesicles with preservation of function. Direct evidence is provided to demonstrate that glycoprotein lib and Ilia and fibrinogen are sufficient for platelet aggregation and to demonstrate that thrombospondin may also contribute to platelet aggregation.

Absorption and polarization spectra of polynuclear p-quinones

1974 ◽  
Vol 39 (6) ◽  
pp. 1532-1540 ◽  
Author(s):  
A. Novák ◽  
M. Titz ◽  
M. Nepraš
Keyword(s):  
Polarization Spectra

scholarly journals Interaction Between VLDL and Phosphatidylcholine Liposomes Generates New γ-LpE-like Particles

Lipids ◽  
2013 ◽  
Vol 49 (2) ◽  
pp. 143-153 ◽  
Author(s):  
Agnieszka Ćwiklińska ◽  
Barbara Kortas-Stempak ◽  
Anna Gliwińska ◽  
Anastasis Pacanis ◽  
Agnieszka Kuchta ◽  
...  
Keyword(s):  
Phosphatidylcholine Liposomes

scholarly journals Effect of the cholesterol content of small unilamellar liposomes on their stability in vivo and in vitro

1980 ◽  
Vol 186 (2) ◽  
pp. 591-598 ◽  
Author(s):  
Christopher Kirby ◽  
Jacqui Clarke ◽  
Gregory Gregoriadis
Keyword(s):  
Blood Plasma ◽  
Intravenous Injection ◽  
Whole Blood ◽  
Cholesterol Content ◽  
Molar Ratio ◽  
Phosphatidylcholine Liposomes ◽  
Effective Use ◽  
Positively Charged

Small unilamellar neutral, negatively and positively charged liposomes composed of egg phosphatidylcholine, various amounts of cholesterol and, when appropriate, phosphatidic acid or stearylamine and containing 6-carboxyfluorescein were injected into mice, incubated with mouse whole blood, plasma or serum or stored at 4°C. Liposomal stability, i.e. the extent to which 6-carboxyfluorescein is retained by liposomes, was dependent on their cholesterol content. (1) Cholesterol-rich (egg phosphatidylcholine/cholesterol, 7:7 molar ratio) liposomes, regardless of surface charge, remained stable in the blood of intravenously injected animals for up to at least 400min. In addition, stability of cholesterol-rich liposomes was largely maintained in vitro in the presence of whole blood, plasma or serum for at least 90min. (2) Cholesterol-poor (egg phosphatidylcholine/cholesterol, 7:2 molar ratio) or cholesterol-free (egg phosphatidylcholine) liposomes lost very rapidly (at most within 2min) much of their stability after intravenous injection or upon contact with whole blood, plasma or serum. Whole blood and to some extent plasma were less detrimental to stability than was serum. (3) After intraperitoneal injection, neutral cholesterol-rich liposomes survived in the peritoneal cavity to enter the blood circulation in their intact form. Liposomes injected intramuscularly also entered the circulation, although with somewhat diminished stability. (4) Stability of neutral and negatively charged cholesterol-rich liposomes stored at 4°C was maintained for several days, and by 53 days it had declined only moderately. Stored liposomes retained their unilamellar structure and their ability to remain stable in the blood after intravenous injection. (5) Control of liposomal stability by adjusting their cholesterol content may help in the design of liposomes for effective use in biological systems in vivo and in vitro.

scholarly journals Effects of Isoflurane, Halothane, and Chloroform on the Interactions and Lateral Organization of Lipids in the Liquid-Ordered Phase

Langmuir ◽  
2011 ◽  
Vol 27 (23) ◽  
pp. 14380-14385 ◽  
Author(s):  
Serhan Turkyilmaz ◽  
Paulo F. Almeida ◽  
Steven L. Regen
Keyword(s):  
Liquid Ordered ◽  
Lateral Organization
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