Modulation of polymorphic properties of dielaidoylphosphatidylethanolamine by the antineoplastic ether lipid 1-O-octadecyl-2-O-methyl-glycero-3-phosphocholine.

The capacity of the antineoplastic ether lipid 1-O-octadecyl-2-O-methyl-glycero-3-phosphocholine (ET-18-OCH3) to modulate the polymorphic properties of dielaidoylphosphatidylethanolamine has been studied using biophysical techniques. Differential scanning calorimetry showed that ET-18-OCH3 depresses the onset of the Lbeta to Lalpha phase transition, decreasing also DeltaH of the transition. At the same time, the onset of the transition from Lalpha to inverted hexagonal HII phase was gradually increased as the ether lipid concentration was increased, totally disappearing at concentrations higher than 5 mol%. Small-angle X-ray diffraction and 31P-NMR confirmed that ET-18-OCH3 induced that the appearance of the inverted hexagonal HII phase was shifted towards higher temperatures completely disappearing at concentrations higher than 5 mol%. These results were used to elaborate a partial phase diagram and they were discussed as a function of the molecular action of ET-18-OCH3.

Cholesterol levels in untreated Spanish hypertensive patients. The Compas Study Group, Spanish Hypertension Society.

In daily practice, arterial hypertension (AHT) and hypercholesterolaemia are frequently associated with the existence of multiple common etiopathogenic interrelationships. This situation leads to an exponential increase in cardiovascular risk for these patients, so it is essential to know the prevalence and therapeutic management of hypercholesterolaemia in the hypertensive patient. This national study analyses the distribution of total cholesterol levels and low-density lipoprotein cholesterol as well as hypercholesterolaemia prevalence and its therapeutic management in the uncontrolled hypertensive Spanish population. We observed mean total cholesterol levels of 227+/-41 mg/dl with a high prevalence of hypercholesterolaemia (34.2%) among hypertensive patients, and the percentage of those patients with "desirable" total cholesterol levels (<200 mg/dl) was <25%. The treated hypertensive patients presented both significantly higher mean cholesterol levels and greater hypercholesterolaemia prevalence than the untreated hypertensive patients. It appears that total cholesterol levels are scarcely related to the presence or non-presence of obesity, diabetes or smoking. Regarding treatment, only 14.6% of the hypercholesterolaemic hypertensive patients received hypolipaemic treatment with statins. These results support the need to introduce measures for better diagnostic and therapeutic management of hypercholesterolaemic hypertensive patients that will lead to a much higher reduction in cardiovascular risk for these patients.

Importance of the tryptophans of gramicidin for its lipid structure modulating activity in lysophosphatidylcholine and phosphatidylethanolamine model membranes. A comparative study employing gramicidin analogs and a synthetic alpha-helical hydrophobic polypeptide.

The importance of the tryptophan residues of gramicidin for the lipid structure modulating activity of this pentadecapeptide was investigated by studying the interaction of gramicidin analogs A, B, C (which have a tryptophan, phenylalanine and tyrosine in position 11, respectively) and tryptophan-N-formylated gramicidin (in which the four tryptophan residues have been formylated) with several phospholipid systems. In addition an alpha-helical model pentadecapeptide (P15) was studied to further test the specificity of the gramicidin-lipid interaction. DSC experiments showed that all the gramicidin analogs produced a significant decrease in the gel to liquid-crystalline transition enthalpy of dipalmitoylphosphatidylcholine. The P15 peptide was much less effective in this respect. In dielaidoylphosphatidylethanolamine the gel----liquid-crystalline transition enthalpy was much less affected by the incorporation of these molecules. In this lipid system tryptophan-N-formylated gramicidin was found to be the most ineffective. 31P-NMR and small angle X-ray diffraction experiments showed that the ability of the peptides to induce bilayer structures in palmitoyllysophosphatidylcholine and HII phase promotion in dielaidoylphosphatidylethanolamine systems follows the order: gramicidin A' (natural mixture) approximately equal to gramicidin A greater than gramicidin B approximately equal to gramicidin C greater than tryptophan-N-formylated gramicidin greater than P15. These results support the hypothesis that the shape of gramicidin and its aggregational behaviour, in which the tryptophan residues play an essential role, are major determinants in the unique lipid structure modulating activity of gramicidin.