Uptake and metabolism of 3H-fatty acid labelled lecithin by normal and atherosclerotic intima in vivo and in vitro

Lipid Replacement Therapy: a natural medicine approach to replacing damaged lipids in cellular membranes and organelles and restoring function

Lipid Replacement Therapy, the use of functional oral supplements containing cell membrane phospholipids and antioxidants, has been used to replace damaged, usually oxidized, membrane glycerophospholipids that accumulate during aging and in various clinical conditions in order to restore cellular function. This approach differs from other dietary and intravenous phospholipid interventions in the composition of phospholipids and their defense against oxidation during storage, ingestion, digestion and uptake as well as the use of protective molecules that noncovalently complex with phospholipid micelles and prevent their enzymatic and bile disruption. Once the phospholipids have been taken in by transport processes, they are protected by several natural mechanisms involving lipid receptors, transport and carrier molecules and circulating cells and lipoproteins until their delivery to tissues and cells where they can again be transferred to intracellular membranes by specific and nonspecific transport systems. Once delivered to membrane sites, they naturally replace and stimulate removal of damaged membrane lipids. Various chronic clinical conditions are characterized by membrane damage, mainly oxidative but also enzymatic, resulting in loss of cellular function. This is readily apparent in mitochondrial inner membranes where oxidative damage to phospholipids like cardiolipin and other molecules results in loss of trans-membrane potential, electron transport function and generation of high-energy molecules. Recent clinical trials have shown the benefits of Lipid Replacement Therapy in restoring mitochondrial function and reducing fatigue in aged subjects and patients with a variety of clinical diagnoses that are characterized by loss of mitochondrial function and include fatigue as a major symptom. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Histochromatographical determination of cholesteryl ester composition in the human atherosclerotic aorta

In 14 human aortas, the cholesteryl ester (CE) composition of fatty spots was investigated histochromatographically. By a special method the intracellular lipid (foam cells) lying in the inner intima could be separated from the extracellular lipid found in the depth of the intima in many cases. The fatty acid pattern of CE of the intracellular lipid differed from that of the extracellular lipid by a relative increase in monoenoic acids (M) and trienoic acids (Tr) as well as by a relative decrease in linoleic acid (D), tetraenoic acids (Ar), and saturated fatty acids (S). In every case, the sum of the polyunsaturated fatty acids (PU) of CE (with 2 to 6 double bonds) was lower in the intracellular than in the extracellular lipid (highest difference: 23,2%, lowest difference: 5,7%). High differences of the PU-values between intra- and extracellular CE were associated with high or low D-values and with low values for Tr, Ar, and HU (high unsaturated fatty acids with more than 4 double bonds) of intracellular CE. Low differences of the PU-values between intra- and extracellular CE were accompanied with high D-values and medium or high values for Tr, Ar, and HU of intracellular CE. The results suggest that the cholesteryl esters in the intracellular lipid lose polyunsaturated fatty acids by the processes of hydrolysis and reesterification which are possibly used for other metabolic processes.

A system for long-term perfusion of rabbit aorta in vitro

In an in vitro system for the perfusion of arterial tissue, the volume of the incubation chamber should be small, and the composition of the medium should be easily modified. The tissue should consist of media and intima only, and the interaction with the medium should occur via the intimal side. Consecutive sampling of the medium and the tissue should be possible. This paper describes a system with these characteristics. Scanning and transmission electron microscopy of the perfused tissue indicated that the endothelium was intact during the first day and that it still covered more than 95% of the surface after 3 days. On the 2nd day, the nonthrombogenic properties of the endothelium were maintained. The medial smooth muscle cells of the inner two-thirds of the preparation were viable during the perfusion, while the cells in the outer one-third were dead from the start. Still, the metabolic activity of the tissue was stable, at least during the 2nd day as assessed by the study of DNA, protein, and lipid synthesis, as well as by oxygen consumption. We conclude that the perfusion system presented here might be useful in the study of the interaction between cellular and humoral components of the blood and the arterial wall.

Removal of fatty acid labelled cholesterol ester, phospholipid and triglyceride from atherosclerotic rabbit aorta in vitro

An organ culture technique was used to investigate the removal of fatty acids incorporated into various lipid fractions in intimal segments of atherosclerotic rabbit aorta. Segments of aorta were pulse-labelled in vitro with [9,10-3H]oleic acid and [1-14C]linoleic acid for 24 h. The incubation medium was replaced with non-radioactive medium and the removal of the endogenously labelled phospholipid, triglyceride and cholesterol ester was followed for a further period of 10 days. Fatty acids incorporated into phospholipid and triglyceride were removed rapidly from the aortic intima, with fractional half-times of 4--5 days. Cholesterol ester fatty acids were removed more slowly from the aortic intima with fractional half-times of 9--12 days. When the removal rate of oleic acid incorporated into phospholipid, triglyceride and cholesterol ester was compared with that of linoleic acid incorporated into the same lipid fractions, no difference between removal of the two fatty acids could be detected with respect to any of the 3 lipid fractions.

[Long-term tissue culture of normal and atherosclerotic human arterial explants (author's transl)]

A method for longterm tissue culture of human arterial explants is described. The explants of normal and atherosclerotic femoral arteries, removed immediately post mortem, were kept in culture for up to 14 days in a biochemically active state. Viability was checked by glucose uptake and lactate production, with daily changes of incubation media and sterility controls. Compared to the well established short term incubation systems where metabolic activity decreases progressively after 6 h, glucose uptake, lactate production and uptake of 3H-oleic acid are linear within 4-14 h. The highest incorporation of 3H-oleic acid is found in phospholipids, the lowest in cholesterol ester. But whilst activity, after the pulse label of 24 h, progressively decreases in phospholipids, it constantly increases in the cholesterol ester fraction as a consequence of the persistant cholesterol esterification.