Diana Petkova

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AIM The aim of this study was to investigate the effects of testosterone replacement therapy (TRT) on erythrocyte membrane (EM) lipid composition and physico-chemical properties in hypogonadal men. METHODS EM isolated from three patients before and after TRT with injectable testosterone undecanoate or testosterone gel were used for analysis of the(More)
Investigations were performed on the influence of resveratrol on the lipid composition, metabolism, fatty acid and peroxide level in plasma membranes of hepatocytes, isolated from aged rats. Hepatocytes were chosen due to the central role of the liver in lipid metabolism and homeostasis. The obtained results showed that the level of sphingomyelin (SM) and(More)
The changes in the phospholipid and fatty acid composition of liver plasma membranes isolated from rats, fed two different diets, containing either saturated or unsaturated fatty acids, were investigated. We established that dietary treatment can considerably modify the fatty acid as well as the phospholipid composition of liver plasma membranes. Lipid(More)
The effect of cholesterol-supplemented diet on the activities of rat liver plasma membrane sphingomyelin-metabolizing enzymes and protein kinase C was studied. Protein kinase C, phosphatidylcholine:ceramide-phosphocholine transferase, and phosphatidylethanolamine:ceramide-phosphoethanolamine transferase activities were found to increase continuously and(More)
1. The influence of insulin on rat liver membrane lipid composition, fluidity, some enzyme activities and asymmetry of microsomal phospholipids were investigated. 2. The total phospholipids and cholesterol were increased in microsomes and reduced in plasma membranes from insulin-treated rats. 3. Of all the investigated enzymes participating in the lipid(More)
The influence of the phospholipid composition and the physico-chemical properties of rat liver plasma membranes on the activity of membrane-bound phospholipase A2 has been investigated. The plasma membrane composition was modified by the aid of exogenous phospholipases A2, C and D, and by butanol treatment. The partially delipidated membranes thus obtained(More)
The changes in the phospholipid composition of spermatozoa plasma membranes after freezing were determined by thin-layer chromatography. The results showed an augmentation of the diphosphatidylglycerol and a diminution of phosphatidylglycerol, phosphatidylserine, and phosphatidylethanolamine in sperm plasma membranes after freezing. In intact sperm cells we(More)
The three-dimensional (3D) cell culture approach offers a means to study cells under conditions that mimic an in vivo environment, thus avoiding the limitations imposed by the conventional two-dimensional (2D) monolayer cell cultures. By using this approach we demonstrated significant differences in the plasma membrane phospholipid composition and(More)
Most in vitro studies use 2-dimensional (2D) monolayer cultures, where cells are forced to adjust to unnatural substrates that differ significantly from the natural 3-dimensional (3D) extracellular matrix that surrounds cells in living organisms. Our analysis demonstrates significant differences in the cholesterol and sphingomyelin content, structural(More)
The age-induced changes of some phospholipid fractions, membrane fluidity and neutral membrane-bound sphingomyelinase (EC 3.1.4.12) activity in rat liver plasma membranes have been investigated. Alterations in the percentage participation of phosphatidylcholine and sphingomyelin with aging have been established. Regression analysis indicated a positive(More)