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Total lipid and membrane lipid analysis of normal animal and human lenses.

Comparisons of lens fiber cell membrane isolation methods were made. Although membrane lipid yield from stirring overnight in hypotonic medium followed by low-speed centrifugation was comparable to that from homogenization and high-speed centrifugation, losses in phosphatidyl ethanolamine were observed with the former method. Lyophilization with vacuum replacement by nitrogen did not exert any deleterious effects. A significant difference in total lens lipid was observed between human and the three species of animals investigated.

Aged↗

Lipids and lipoproteins in hyperlipidemia type IIa during treatment with different lipid lowering drugs.

In the present study we examined the effect of different lipid lowering drugs on lipids and lipoproteins in hyperlipoproteinemia type IIa. We have treated over 24 weeks 10 patients with 900 mg beta-pyridylcarbinol daily, 11 patients with 3 g of xantinolnicotinate, 4 patients with 600 mg bezafibrate daily and 10 patients with a combination of 2.4 g inositolnicotinate and 1.5 g clofibrate daily. One patient with familial hypercholesterolemia (untreated total cholesterol 800 mg%) received a combined drug treatment during 5 years. Total cholesterol decreased to 200 mg%, mainly due to decreases in LDL-cholesterol. However in HDL significant decreases of about 50% could be observed. Treatment with the four different drugs showed significant decrements in low density lipoproteins (LDL) whereas an increase of protective high density lipoproteins could not be observed.

Adolescent↗

[A rapid analysis of the lipid profile. A comparative study of different analytical methods for determination of blood lipids].

A simple and rapid analytical assay for determination of total cholesterol, HDL-cholesterol and triglycerides in capillary blood samples has been compared with established laboratory methods in a group of 41 test subjects. The new method produces results that are fully acceptable for determination of these three lipid parameters, and agree well with the results obtained in serum by established laboratory methods. The Cholestech LDX analyser may be useful for providing rapid and accurate measurements of the lipid profile, including total cholesterol, triglycerides and HDL-cholesterol. Its small size, the speed of analysis and the fact that it is easy to use make the Cholestech LDX a suitable instrument for use in out-patient clinics and primary care medicine.

Blood Chemical Analysis↗

[Comparative effect of polymyxin B on lipid bilayer membranes with different lipid composition].

The aim of the work was to characterize the role of negatively charged lipids (cardiolipin and lauric acid) in the increase of ionic permeability of the membrane under the action of polymyxin B. Cardiolipin or lauric acid were added into membrane-forming solution in concentration close to that in the membrane of bacterial cell. It resulted in modification of membranes by these lipids. The obtained membranes had a higher ionic permeability in the presence of polymyxin B. However the comparison of different effects can lead to the conclusion that free fatty acid are responsible for the major part of the effect. It is concluded that the character of damage of the bilayer by polymyxin is diverse: polymyxin B forms ionic canals with lauric acid, whereas there is unspecific destruction of BLM by the polymyxin interacting with cardiolipin.

Cardiolipins↗

Increased generation of lipid-derived and ascorbate free radicals by L1210 cells exposed to the ether lipid edelfosine.

Using the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone, we have detected a lipid-derived carbon-centered free radical generated from intact L1210 lymphoblastic leukemia cells that were exposed to 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (edelfosine or ET-18-OCH3) and oxidative stress. The spectral characteristics, including hyperfine splitting constants of aN = 15.61G and aH = 2.65G, were consistent with the spin trapping of an alkyl radical. Radical detection required iron and prior enrichment of cellular components with the polyunsaturated fatty acid docosahexaenoic acid; unmodified cells failed to generate detectable free radical. Ascorbate further enhanced radical generation. The detection of lipid-derived free radicals when intact cells are exposed to edelfosine provides further evidence that oxidative stress may play an important role in the cytotoxic mechanism of this class of anticancer drug.

Animals↗

Targeted mutagenesis of acyl-lipid desaturases in Synechocystis: evidence for the important roles of polyunsaturated membrane lipids in growth, respiration and photosynthesis.

Acyl-lipid desaturases introduce double bonds (unsaturated bonds) at specifically defined positions in fatty acids that are esterified to the glycerol backbone of membrane glycerolipids. The desA, desB and desD genes of Synechocystis sp. PCC 6803 encode acyl-lipid desaturases that introduce double bonds at the delta12, omega3 and delta6 positions of C18 fatty acids respectively. The mutation of each of these genes by insertion of an antibiotic resistance gene cartridge completely eliminated the corresponding desaturation reaction. This system allowed us to manipulate the number of unsaturated bonds in membrane glycerolipids in this organism in a step-wise manner. Comparisons of the variously mutated cells revealed that the replacement of all polyunsaturated fatty acids by a monounsaturated fatty acid suppressed growth of the cells at low temperature and, moreover, it decreased the tolerance of the cells to photoinhibition of photosynthesis at low temperature by suppressing recovery of the photosystem II protein complex from photoinhibitory damage. However, the replacement of tri- and tetraunsaturated fatty acids by a diunsaturated fatty acid did not have such effects. These findings indicate that polyunsaturated fatty acids are important in protecting the photosynthetic machinery from photoinhibition at low temperatures.

Calorimetry, Differential Scanning↗

[Role of lipid composition in the kinetics of free radical lipid oxidation in photoreceptor membranes].

The initial rate of lipid peroxidation (LPO) in photoreceptor membranes (PRM) of walleye pollock is 1.8--2.3 times higher than in frog PRM. Rhodopsin bleaching leads to an increase of LPO initial rate in PRM while having no effect on LPO in walleye pollack PRM. The content of unsaturated fatty acids in walleye pollock PRM is 1.4 times greater than in frog PRM. It is suggested that differences in LPO kinetics in PRM of walleye pollack and frog are caused by the differences in the lipid composition of the membranes (primarily by a high level of phospholipid molecular species with two unsaturated fatty acid residues in walleye pollock retina rod outer segments).

Animals↗

Lipid and cell membranes in the presence of gadolinium and other ions with high affinity to lipids. 1. Dipole and diffuse components of the boundary potential.

Two methods were used for monitoring the changes in the boundary and surface potentials induced by Gd3+ adsorption--the method of intramembranous field compensation applied to planar BLM and electrophoresis of liposomes, respectively. The data of both methods agree well in the case of membranes made from phosphatidylcholine (PC), in contrast to those made from phosphatidylserine (PS). In the latter case, they show a significant discrepancy between potential amplitudes even within the micromolar range of Gd3+ concentrations because of cation-induced changes in the dipole component of the boundary potential. The adsorption of these cations with extremely high affinities to lipids was described by the theory of diffuse double layer (Gouy-Chapman-Stern) combined with the condition of mass balance, which is essential in the case of limited volumes of real systems. The electrokinetic data for PS and PC liposomes are in good agreement with the modified theory and correlate well with the Gd3+ association constants of 5.10(4) and 10(3) M-1, respectively. The same theory was used to extract the changes in the dipole component from the measured changes in the PS membrane boundary potential. The dependence of this component on the number of binding sites occupied by cation was shown to be nonlinear but cooperative with the step-like increase of dipole potential up to about 140 mV (positive inside the membrane) at the Gd3+ concentration around the zero charge point of the PS membranes. This potential corresponds to the structural changes in the lipid bilayers which are discussed with respect to the Gd3+ blocking effects on the mechanosensitive channels.

Cell Membrane↗

[Lipid pores and life time of lipid bilayer membranes in gel and liquid crystal states].

The lifetime of lipid bilayer membranes formed from hydrogenated egg lecithin has been studied at the phase transition from liquid crystalline state to the gel. It was shown the lowering of the membrane stability at the phase transition temperature of hydrogenated egg lecithin. Using lifetime values and measured surface tension of bilayer the critical radius of transmembrane pore has been evaluated in comparison with experimental data, obtained by transmembrane current fluctuation registration. It was shown that lifetimes of bilayer lipid membrane in gel state conform data, derived from Deryagin-Gutop-Prokhorov's theory. The radii of pores corresponded to maximal transmembrane current fluctuations are close to critical values of pores in the gel state.

Lipid Bilayers↗

Normal canine lipid profiles and effects of experimentally induced pancreatitis and hepatic necrosis on lipids.

Normal lipid profiles (total lipids, total cholesterol, phospholipids, free fatty acids, triglycerides, and lipoproteins) were determined in 23 clinic-reared dogs and 26 client-owned dogs. A significantly higher concentration of cholesterol was found in client-owned dogs as compared with clinic-reared dogs. Hepatic necorosis, induced by CCl4, resulted only in a significant decrease in triglycerides. Acute pancreatitis, induced by major and minor pancreatic duct ligations, resulted in a significant increase in free fatty acids and low-density lipoprotein with a decrease in high-density lipoprotein-2.

Animals↗

[Comparison of effects of two kinds of soluble algae polysaccharide on blood lipid, liver lipid, platelet aggregation and growth in rats].

SD rats were fed with 1% cholesterol and 0.2% cholate for eight weeks. Sodium alginate and carrageenan, two kinds of soluble algae polysaccharide, were added to the fodder for the trial groups and none added for the control one. Results showed that 5% sodium alginate could lower lipid levels in the blood and liver and platelet aggregation (P < 0.05) in rats, but not affect their food intake and growth. Addition with 5% or 10% carrageenan had no obvious effects on lowering blood lipid and liver total cholesterol (P > 0.05), could not lower the ratio of liver weight to body weight, and had no stable (or sure) effect on lowering platelet aggregation. Ten percent of carrageenan could decrease their mean body weight by 12.17% in rats (P > 0.05), but a few rats suffered from slight diarrhea.

Alginates↗

Infantile form of so-called neuronal ceroid lipofuscinosis: lipid biochemical studies, fatty acid analysis of cerebroside sulfatides and sphingomyelin, myelin density profile and lipid composition.

The biochemical analysis of a case of infantile neuronal ceroid lipofuscinosis, as determined by clinical and neuropathological findings, is presented. A diminished amount of solids is found, the amount of lipids is 30% of the normal as expressed in lyophilized tissue. The yield of myelin isolated by the density gradient is 1.8% of the normal. Phospholipid patterns show a reduction in ethanolamine phosphoglyceride, N-acetylneuraminic acid is extremely low and sphingolipids are largely reduced, cerebrosides being most affected (2.5% of the normal). In cerebrosides and sulfatides the decrease in very long chain fatty acids is important, but the deficiency in any type (including hydroxy compounds) is not too dramatic. According to the aspect under electron microscopy, the density profile, and the biochemical composition of the subfractions, isolated myelin is close to normal. The loss of the myelin sheath appears to reflect a Wallerian degeneration in the CNS: myelin loss is a secondary effect. This disease, from a biochemical point of view, seems to be the ideal control for leukodystrophies.

Atrophy↗

[Hormonal contraception and lipid metabolism. Prospective and retrospective studies of lipid metabolic parameters during the use of contraceptives].

Remarkable changes of several parameters of lipid metabolism were observed in a retrospective study of women, who had used different oral contraceptives for a longer time, in comparison with women without any hormonal contraception. In contrast, under the conditions of a prospective double-blind study no statistically significant alterations of the same parameters were seen under the use of two oral contraceptives different in dosage. Nevertheless, oral contraceptives should not be prescribed to patients with hyperlipidaemia.

Adult↗

[Lipid metabolic disorders and lipid peroxidation in patients with the nephrotic syndrome].

Lipid metabolism was studied in 161 patients with renal diseases, 62 of them had nephrotic syndrome (NS). The measurements were made of cholesterol, triglycerides, dienic conjugates, B2-microglobulins in urine and blood, functional and morphological parameters, red cell resistance to peroxide hemolysis. It was found that NS patients, especially those with additional renal failure, displayed high-intensity lipoperoxidation (LPO). LPO intensity proved unrelated to NS etiology. NS-associated hyperlipidemia gives rise to multifunctional biomembrane instability responsible for antioxidant disorders.

Adult↗

Influences of hypothyroidism on lipid composition and inositol lipid-linked receptors responsiveness and protein kinase C (PKC) activity in the cerebral cortex of Lewis rats.

The influence of hypothyroidism (HO) induced by treatment with propylthiouracil on lipid composition, receptor responsiveness of M1-muscarinic receptors (M1AChRs) and metabotropic glutamate receptors (mGluRs) as well as on protein kinase C (PKC) activity was investigated in the cerebral cortex of Lewis rats. HO did not influence the lipid composition. There was a significant 2-fold increase of efficacy and 6-fold decrease of potency of carbachol-induced inositol phosphate (IP) accumulation in HO, with respect to control rats. The efficacy of trans-(1S,3R)-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD)-induced IP accumulation was also higher in HO (by 50%), without differences in EC50 values. The activities of soluble calcium-dependent and calcium-independent PKC were higher in HO than in control rats (both roughly 30%); membrane-associated PKCs were not modified. The data indicate that HO induces an increased responsiveness of M1AChRs and mGluRs and a rise in the soluble PKC activity that could be available and ready for translocation.

Animals↗

Maximum lipid reduction by partial ileal bypass: a test of the lipid-atherosclerosis hypothesis.

Atherosclerosis is the process responsible for our national epidemic of coronary heart disease. A primary and proven atherosclerotic risk factor is the plasma cholesterol concentration. Yet, proof that a reduction in plasma cholesterol level results in a reduction in the incidence or severity of atherosclerosis and atherosclerotic cardiovascular disease still requires conclusive documentation. The controversial methods of operation and inconclusive results of concluded first and second generation trials are reviewed. These data clearly demonstrate that a definitive test of the lipid hypothesis has not been reported. Evidence is presented to show that the partial ileal bypass operation most nearly fulfills the six features of an "ideal" lipid lowering trial modality: maximum effectiveness (50% cholesterol reduction); known mechanism of action; no response "escape" or "rebound"; obligatory effect without patient cooperation; minimal side effects; and relative safety. The basic design and protocol of the National Heart and Lung Institute Program on Surgical Control of the Hyperlipidemias, a secondary intervention trial using a combination of diet therapy and partial ileal bypass surgery, are outlined.

Arteriosclerosis↗

Cadmium leads to stimulated expression of the lipid transfer protein genes in barley: implications for the involvement of lipid transfer proteins in wax assembly.

In order to investigate the nature of genes expressed in leaf epidermal cells of higher plants, we have identified the nucleotide sequence of a cDNA designated ltp 7a2b encoding a novel nonspecific lipid transfer protein of barley (Hordeum vulgare L. cv. Gerbel). The cDNA of 755 basepairs contains an open reading frame of 366 nucleotides coding for a 12.3-kDa polypeptide. The first 29 amino acids constitute the putative signal peptide, characteristic for targeting to the secretory pathway. Analysis of mRNA levels by Northern blotting indicated that ltp 7a2b is preferentially expressed in the leaf epidermis. Levels of mRNA decreased during ageing of leaf tissue. Expression of ltp 7a2b was stimulated by a factor of 2 - 3 when the seedlings were grown in the presence of cadmium (10 - 1600 microM). Concomitantly, the primary leaves of Cd-exposed seedlings contained elevated levels of abscisic acid and thicker was layer of the cuticle. At 100 microM Cd in the hydroponic medium, the was cover was increased by 50%. The increase in abscisic acid content, ltp 7a2b mRNA and was coverage was either not seen, or seen much less, in Ni- and Zn-stressed seedlings. The data add circumstantial evidence to the recently proposed hypothesis that nonspecific lipid transfer proteins function in transfer of cutin and/or wax monomers from the site of synthesis in the cell to the cuticle.

Amino Acid Sequence↗

[Lipid lowering therapy for primary prevention of coronary heart disease--pro lipid lowering therapy].

The high rate of coronary artery disease (CAD) mortality needs preventive intervention. Several studies have documented the effectiveness of LDL-cholesterol lowering in CAD primary prevention. The West of Scotland Prevention Study resulted in risk reduction by about one third through LDL-cholesterol lowering. The data indicate that specifically patients at high risk benefit from lipid reduction. High risk patients have besides high LDL-cholesterol one or more additional risk factors such as family history of premature coronary artery disease, hypertension, smoking, low HDL-cholesterol or diabetes. Therapy primarily aims at life style changes, secession of smoking and weight reduction as well as dietary changes to achieve LDL-cholesterol levels of 115-175 mg/dl (3-4.5 mmol/L), depending on the individual risk constellation. This strategy allows to reduce the number of patients needed to treat in order to prevent one CAD event (56 in isolated hypercholesterolemia) to 14-24 in high risk persons, approaching the number (n = 13) known for effective lipid lowering in secondary prevention of coronary heart disease. Given the fact that only one third of patients suffering from a myocardial is likely to survive the first year after the event, its time for physicians to identify patients at high risk for coronary artery disease. This LDL-cholesterol lowering in primary prevention is an important and successful approach in preventive medicine. The high risk strategy for coronary primary prevention has shown to be cost effective more or at least similar to the treatment of hypertension.

Cholesterol, LDL↗