Alleviation of drug withdrawal symptoms by treatment with a potent mixture of natural lipids

Lamellar liquid crystals maintain keratinocytes' membrane fluidity: An AFM qualitative and quantitative study

Despite extensive investigations of lamellar liquid crystals for dermal application, the effects of these systems at the cellular level are still not well elucidated. The key aim of this study was to determine the elasticity and morphological features of keratinocytes after exposure to a lamellar liquid crystal system (LLCS) using atomic force microscopy (AFM) as the method of choice. Prior to AFM assessment, a cell proliferation test and light plus fluorescence imaging were applied to determine the sub-toxic concentration of LLCS. According to the AFM results, slightly altered morphology was observed in the case of fixed keratinocytes, while an intact morphology was visualized on live cells. From the quantitative study, decreased Young's moduli were determined for fixed cells (i.e., 8.6 vs. 15.2 MPa and 1.3 vs. 2.9 MPa for ethanol or PFA-fixed LLCS-treated vs. control cells, respectively) and live cells (i.e., ranging from 0.6 to 2.8 for LLCS-treated vs. 1.1-4.5 MPa for untreated cells), clearly demonstrating increased cell elasticity. This is related to improved membrane fluidity as a consequence of interactions between the acyl chains of cell membrane phosphatidylcholine and those of LLCS. What seems to be of major importance is that the study confirms the potential clinical relevance of such systems in treatment of aged skin with characteristically more rigid epithelial cells.

An emerging complimentary medicine-yolk oil made from heating method

Yolk oil is common in Asia. According to the Flora Sinensis, yolk oil is a multipurpose medicine, with specific dermatological and fever indications. Nowadays, it is generally used as a complimentary medicine for heart diseases. Yolk oil can be made from heating or chemical extraction method. It is generally believed that yolk oil made from heating (YOheat) method is more effective as a medicine than that from extraction (YOext). The technical details of the heating method remain an issue of argument, including the degree of char and the threat of carcinogens formed during the heating process. Most yolk oil related studies used YOext as research material. Nevertheless, animal studies have showed that YOheat reduced triglycerides and total cholesterol in rodent liver. It is expected an easy-to-make complimentary medicine like YOheat may become even more common and thus evidence based studies should be conducted to verify its pharmacological effects and safety.

An approach to AIDS therapy using hyperthermia and membrane modification

Altering the biophysical characteristics of cell membranes by diet and membrane perturbing agents markedly influences thermosensitivity of cells. Likewise, manipulation of viral envelopes either by altering their lipid composition by diet or by the use of agents that perturb the lipid envelope influence infectivity of enveloped viruses and the progression of viral disease. The use of hyperthermia and envelope modification as a combined approach to treat AIDS has until now neither been suggested nor attempted. On the basis of my previous work and a review of the literature, I theorize that the combination of hyperthermia with procedures designed to alter the viral envelope will likely result in an increased viral sensitivity and be useful clinically for treatment of patients with enveloped viral diseases such as AIDS.

Lipid requirements of human T lymphocytes stimulated with mitogen in serum-free medium. Membrane "fluidity" changes are an artefact of lipid (AL721) uptake by monocytes

A correlation has been sought between the effects of lipids on membrane fluidity and mitogen responsiveness of human peripheral blood lymphocytes (PBL). Cholesterol and the reputedly potent membrane fluidizing agent AL721 (1) were used for these studies. However, the large AL721 induced increase in membrane "fluidity", assessed by steady state polarization of the probe 1,6-diphenyl-1,3,5-hexatriene (DPH), was found to be an artefact arising from lipid uptake by monocytes. Mitogen responses were enhanced by AL721 but unaffected by cholesterol. It is concluded that AL721 does not exert its effect through enhanced triggering of cells by altered membrane fluidity but rather that lymphocytes require an exogenous source of phospholipids/triglycerides for optimal growth in vitro, although they can synthesize sufficient cholesterol to meet their own needs.

Membrane effects of ethanol: bulk lipid versus lipid domains

It has been well-established that ethanol fluidizes the bulk lipid of membranes and that this effect may alter cell function and be involved in ethanol sensitivity and tolerance. This hypothesis has been supported in several studies, however, there is also a considerable amount of data that do not support such an explanation, e.g., direct effect of ethanol on proteins, other membrane acting drugs, temperature effects, effects of ethanol on aged membranes and inconsistent effects of chronic ethanol consumption on lipid content. This review examined the bulk membrane fluidization hypothesis in light of those data and proposed a modification of the bulk membrane hypothesis that is based on recent data that show that ethanol and other alcohols have a specific effect on the structural properties of different membrane domains. This specific effect of ethanol is discussed within the context of how changes in fluidity of domains may alter membrane function.

AL721, a novel membrane fluidizer

AL721, which is a novel lipid mixture extracted from egg yolks, is believed to be a therapeutic pharmacologic agent. AL721 interacts with membranes of various types of cells with a common mode of action. AL721 modifies cellular membrane composition and fluidity through passive extraction and/or exchange of cholesterol. Physiologically diminished cell function due to rigidification of its membrane is reversible both in vitro and in vivo by AL721. Fluidization of aged membranes with AL721 has been shown to restore brain serotonin receptor function both in vitro and in vivo. AL721 can also successfully restore deficient immune responsiveness of lymphocytes to mitogen stimulation in aged subjects. Drug tolerance to morphine and ethanol develops upon elevation of the viscosity of neuronal cell membranes in order to counteract the fluidization effect of the drug. Treatment of rigidified cellular membranes with AL721 in vivo can markedly reduce withdrawal symptoms. The virucidal effect of AL721 on the human immunodeficiency virus is believed to operate by lowering of viral membrane cholesterol thus interfering with the binding of the viral antigen to the host cell. Non-toxicity of AL721 is clearly demonstrated in animal and human safety studies.

Augmentation of mitogen responsiveness in the aged by a special lipid diet AL 721

Diminished immune responses in aging may be partially due to alteration of the lipid composition of membrane and a decrease in membrane fluidity. The effect of a daily diet of 10 g active lipid (AL 721) on the mitogen responsiveness of peripheral blood mononuclear cells (PBMC) from aged volunteers was studied. AL 721 is a mixture of lipids from hen egg yolk which was formulated for in vivo rectification of rigidified cell membranes in an attempt to restore proper physiological function. After 3 weeks on the diet, six aged participants displayed a significant increase in lymphocyte responsiveness to mitogens, while in four the responsiveness was unaffected, or increased insignificantly. In all six participants, a decline in lymphocyte responsiveness was observed a week after termination of the diet. Our preliminary results indicate that improvement of immune functions in the aged may be achieved by dietary manipulation of lipids. This innocuous approach seems to be of potential value and merits further studies.

Lymphocyte membrane lipid composition and mitogen responsiveness in chickens: role of membrane "fluidity"

After establishing optimal conditions for measuring the membrane lipid packing density ("fluidity") of chicken peripheral blood lymphocytes, the fluidity was modulated in vitro by incubation in cholesterol or phospholipid ("active lipid", AL)-enriched serum-free tissue culture medium. The effect of these lipids on mitogen responsiveness was then investigated, the aim being to determine whether the observed enhancement/suppression was membrane mediated, i.e. explainable by fluidity changes. Chicken peripheral blood lymphocytes exhibited no requirement for exogenous cholesterol; low concentrations did not affect the mitogen response while the higher concentrations, which induced a measurable decrease in membrane fluidity, were usually mildly suppressive. Pre-incubation did not increase this suppressive effect and we believe it not to be membrane mediated. AL, at low concentrations which induced no changes in membrane fluidity, prolonged the phytohemagglutinin response, enhancement being evident only after the peak; we interpret this as a nutrient effect. At the higher concentrations, which induced large increases in fluidity, a transient enhancement was followed by suppression; suppression was delayed in onset when AL was added 4 h after phytohemagglutinin stimulation. It is therefore an early event which may be mediated through changes in membrane fluidity.

Neurochemical aspects of depression: the past and the future?

The role of aberrant neurochemical substrates in the etiology of depression and the neurochemical mechanisms of antidepressant therapies have been the subjects of many hypotheses in the last 30 years. Pharmacological studies of early antidepressant drugs indicated that brain monoamines were significantly affected by these drugs and these led to the formulation of the biogenic amine hypothesis of depression. Although this hypothesis has been of heuristic value in the study of drug mechanisms and has provided a basis for screening drugs for antidepressant potential, deficiencies in it have become apparent. Neuroanatomical and neurochemical considerations favour the view that brain noradrenaline and serotonin systems may serve as bias adjusting systems for each other and numerous other neural systems. As a consequence of such a relationship, a primary defect in some other neural system would appear amplified in measurements of serotonin or noradrenaline. A possible site for this primary defect may be in membrane composition and function. Recent studies have found that typical and other antidepressant therapies have a pronounced effect on membrane lipids. Thus, in view of the important functions of membrane lipids and the fact that they have been linked to the initiation and development of a number of other disease processes, it is now suggested that consideration be given to them as playing primary causal roles in the etiology of depression and as a site of action for antidepressant drugs.

A special lipid mixture for membrane fluidization

The potency for membrane fluidization of mixtures containing neutral lipids (NL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from hen egg yolk was tested on human erythrocytes and lymphocytes. A specific mixture consisting of 70% NL, 20% PC and 10% PE was found to be a potent membrane fluidizer operating almost exclusively by extracting membrane cholesterol. Spectral results and electron micrographs indicate that aqueous dispersion of this mixture consists of chylomicron-like assemblies where the neutral lipids provide the hydrophobic core on the surface of which phospholipids are spread as a monolayer.

Enhancement of the response of ageing mouse lymphocytes by in vitro treatment with lecithin

The effect of treatment with phosphatidylcholine (lecithin) has been examined on splenocytes from young (6 months) and aged (greater than 20 months) (C3H/eB X C57BL/6)F1 male mice, by probing their responsiveness to proliferative signals of mitogens and mixed lymphocyte reaction. This study was initiated since old mice have been known to manifest an increased ratio of cholesterol: phospholipids (C/PL) in their plasma membranes. Unlike the case in young mice, enhancement in proliferative responses was demonstrated on cells from the old after incubation with lecithin. This enhancement was achieved using a variety of methods by which lymphocytes were exposed to the lipids, and which were all designed to reduce the C/PL ratio in the plasma membrane. The observed differences in response to lecithin treatment between young and old did not stem from different extents of lipid incorporation, and seems unlikely to be a result of modified binding of the mitogens after treatment with the lipid. The data suggest that the normal functional performance of specific reactions, which decline with age, may be restored artificially at an appropriate age, if other complementary functions have not been damaged.