Search results for "Membrane Lipids"
showing 10 items of 80 documents
Vitamin A deficiency causes oxidative damage to liver mitochondria in rats.
2000
Mitochondrial damage in rat liver induced by chronic vitamin A-deficiency was studied using three different groups of rats: (i) control rats, (ii) rats fed a vitamin A-free diet until 50 d after birth and (iii) vitamin A-deficient rats re-fed a control diet for 30 d. No statistical difference in body weight and food intake was found between control and vitamin A-deficient rats. Liver GSH concentration was similar in both groups. However, in vitamin A-deficient rats, the mitochondrial GSH/GSSG ratio was significantly lower and the levels of malondialdehyde (MDA) and 8-oxo-7, 8-dihydro-2'-deoxyguanosine (oxo8dG) were higher when compared to control rats. These values were partially restored i…
Vitamin A Inhibits Doxorubicin-Induced Membrane Lipid Peroxidation in Rat Tissues in Vivo
1993
The antioxidant activity of vitamin A against lipid peroxidation induced by doxorubicin in rat tissues in vivo was investigated. A single ip injection of doxorubicin (30 mg/kg body wt) markedly raised the level of peroxidated lipids measured as TBARS and conjugated dienes in heart and brain membrane preparations. Other tissues, such as retina and liver, did not show any increase of lipid peroxides over control values. Pretreatment of rats with two daily subcutaneous injections of retinol palmitate (0.25 g/kg body wt), for 2 days, before injecting doxorubicin, inhibited peroxidation of heart and brain membrane lipids. The antioxidant action of vitamin A does not appear to be mediated by enha…
A minimal hydrophobicity is needed to employ amphiphilic p(HPMA)-co-p(LMA) random copolymers in membrane research.
2014
Because a polymer environment might be milder than a detergent micelle, amphiphilic polymers have attracted attention as alternatives to detergents in membrane biochemistry. The polymer poly[N-(2-hydroxypropyl)-methacrylamid] [p(HPMA)] has recently been modified with hydrophobic lauryl methacrylate (LMA) moieties, resulting in the synthesis of amphiphilic p(HPMA)-co-p(LMA) polymers. p(HPMA)-co-p(LMA) polymers with a LMA content of 5 or 15% have unstable hydrophobic cores. This, on one hand, promotes interactions of the hydrophobic LMA moieties with membranes, resulting in membrane rupture, but at the same time prevents formation of a hydrophobic, membrane mimetic environment that is suffici…
Proteins and enzymes of the peroxisomal membrane in mammals.
1993
Proteins of the peroxisomal membrane can be schematically divided into two groups, one being made up of more or less characterized proteins with generally unknown functions and the other consisting of enzyme activities of which the corresponding proteins have not been characterized. In the present report, these proteins and enzymes are described with the addition of unpublished results regarding their induction by peroxisome proliferators at the post-transcriptional level. Integral membrane proteins (IMPs) can be isolated using an alkaline solution of sodium carbonate. A dozen of preponderant IMPs can be seen on sodium dodecyl sulfate polyacrylamide gel electrophoresis, and the major band c…
Organic derivatives of mercury and tin as promoters of membrane lipid peroxidation.
2008
The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement …
Mixtures of lecithin with polymerizable derivatives of cholesterol. A monolayer film balance study.
1986
One of the best investigated binary lipid mixtures is the lecithin-cholesterol system. We show here that it is possible to modify the cholesterol in such a way that it can be polymerized without changing its behaviour in mixtures with lecithin. The polymerizable derivatives exhibit a very similar phase diagram in the mixture with dipalmitoyl-phosphatidylcholine as the cholesterol itself. This is demonstrated by filmbalance measurements.
Role of RNA Motifs in RNA Interaction with Membrane Lipid Rafts: Implications for Therapeutic Applications of Exosomal RNAs
2021
RNA motifs may promote interactions with exosomes (EXO-motifs) and lipid rafts (RAFT-motifs) that are enriched in exosomal membranes. These interactions can promote selective RNA loading into exosomes. We quantified the affinity between RNA aptamers containing various EXO- and RAFT-motifs and membrane lipid rafts in a liposome model of exosomes by determining the dissociation constants. Analysis of the secondary structure of RNA molecules provided data about the possible location of EXO- and RAFT-motifs within the RNA structure. The affinity of RNAs containing RAFT-motifs (UUGU, UCCC, CUCC, CCCU) and some EXO-motifs (CCCU, UCCU) to rafted liposomes is higher in comparison to aptamers withou…
Binding of RNA Aptamers to Membrane Lipid Rafts: Implications for Exosomal miRNAs Transfer from Cancer to Immune Cells
2020
Intraluminal vesicles (ILVs) are released into the extracellular space as exosomes after the fusion of multivesicular bodies (MVBs) with the plasma membrane. miRNAs are delivered to the raft-like region of MVB by RNA-binding proteins (RBPs). RNA loading into exosomes can be either through direct interaction between RNA and the raft-like region of the MVB membrane, or through interaction between an RBP&ndash
Platelet membrane fluidity and platelet membrane lipid pattern in essential hypertension
1995
In a group of subjects with essential hypertension platelets were studied in resting conditions: platelet membrane fluidity was measured with the fluorescent probe 1.4-(trimethylamino)-phenyl-4-phenylhexatriene (TMA-DPH), platelet membrane cholesterol/phospholipid ratio was evaluated separating the membrane lipids with column chromatography, and platelet membrane individual phospholipids were determined using two-dimensional thin-layer chromatography. From the obtained results, it is evident that platelet membrane fluidity does not differentiate normals from hypertensives; platelet membrane cholesterol/phospholipid ratio is increased in hypertensives, while of the platelet membrane individu…
Chapter 23: Choline, a precursor of acetylcholine and phospholipids in the brain
1993
Publisher Summary The plasma level of free choline is remarkably constant at about 10 pM in animals and human. Ingestion of food, especially when rich in choline or lecithin, transiently elevates the plasma choline level up to 20 pM or more. In contrast, choline-deficient diet leads to a reduction of the plasma level by about 50%. Choline is considered an essential nutrient, which is predominantly supplied as phosphatidylcholine (lecithin). For a long time, neuroscientists have been intrigued by the fact that choline is a precursor for the biosynthesis of both acetylcholine (ACh) and phospholipids. For 50 years, lecithin has been marketed in Europe as a drug that was claimed to prevent exha…