A chronic hypercoagulable state and life-long platelet activation in beta thalassemia major.

Increased frequency of thromboembolic events has been recently observed in patients with thalassemia major (TM), causing hypoxemia and cor pulmonale. Autopsy findings demonstrated "old" and recent pulmonary and renal infarcts as well as premature atherosclerosis. Studies to determine hypercoagulability showed: impaired platelet aggregation, increased circulating platelet aggregates, shortened platelet survival, enhanced excretion of urinary metabolites of thromboxane A2 (TXA2) and prostacyclin and decreased plasma levels of Protein C, Protein S or anti-thrombin III.

Characterization of the core and surface of human plasma lipoproteins. A study based on the use of five fluorophores.

The physical properties of the core and the surface of five classes of human plasma lipoproteins were investigated using five fluorescent probes. The location of the fluorescence probes in the lipoprotein assembly was determined using collisional quenching and resonance energy transfer. The fluorophores monitor different regions of the lipoproteins, as shown by fluorescence quenching.

The interaction of cholesterol and cholest-4-en-3-one with dipalmitoylphosphatidylcholine. Comparison based on the use of three fluorophores.

This study compares cholesterol-phospholipid and cholest-4-en-3-one-phospholipid interactions by their effect on thermotropic behavior of dipalmitoylphosphatidylcholine bilayers. This was approached by determining the temperature-dependent steady-state fluorescence anisotropy of three fluorophores; diphenylhexatriene (DPH), hydroxy-coumarin (HC) and trans-parinaric acid (TPA). The fluorophores monitor different lateral and vertical locations of the lipid bilayers; DPH and HC average laterally the properties of the hydrophobic and headgroup regions of the bilayer, respectively, while TPA distribution is determined by the lateral organization of the bilayer.

Interaction of trans-parinaric acid with phosphatidylcholine bilayers: comparison with the effect of other fluorophores.

The effect of the fluorophore trans-parinaric acid on the structure of lipid bilayer was studied and compared with the effect of other 'perturbants'. These include commonly used fluorophores (diphenylhexatriene, heptadecylhydroxycoumarin, cis-parinaric acid and two fatty acids, palmitic and oleic acids). Differential scanning calorimetry (DSC) and proton nuclear magnetic resonance techniques were used to evaluate structural changes in the lipid bilayers.

Characterization of the fluorophore 4-heptadecyl-7-hydroxycoumarin: a probe for the head-group region of lipid bilayers and biological membranes.

The fluorophore 4-heptadecyl-7-hydroxycoumarin was used as a probe to study the properties of phospholipid bilayers at the lipid-water interface. To this end, the steady-state fluorescence anisotropy, the differential polarized phase fluorometry, and the emission lifetime of the fluorophore were measured in isotropic viscous medium, in lipid vesicles, and in the membrane of vesicular stomatitis virus. In the isotropic medium (glycerol), the probe showed an increase in the steady-state fluorescence anisotropy with a decrease in temperature, but the emission lifetime was unaffected by the change in temperature.