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At least 991 records · Page 55Linked to original sources
PubMed2005

[Unsaturated fatty acids intake and breast cancer risk: epidemiological data review].

The relationship between fatty acids and breast cancer has been debated for long, because of the high frequency of breast cancer and the contradictory results from the numerous studies devoted to this issue. The present review includes case-control and prospective studies, according to specified methodological criteria, which estimated the exposure to monounsaturated fatty acids (MUFA) and n-6 and n-3 polyunsaturated fatty acids (PUFA) using dietary questionnaires or markers (plasma, erythrocytes, adipose tissue). The relationship between MUFA intake and breast cancer risk seems to depend on the contributing food : neutral or beneficial for vegetable oil, rather deleterious for animal products. Contrary to data from animal experiments, human studies do not show an increase of breast cancer risk with n-6 PUFA intake. Estimating the risk associated with alpha-linolenic acid appears difficult due to the incompleteness of food composition tables and studies on biomarkers remain few. The same applies to long-chain n-3 PUFA despite the suggestion of a decrease in risk, in agreement with animal studies. However, it is difficult in human to disentangle the effect of nutrient intake from that of contributing foods or even nutritional profile.

Antioxidants↗
PubMed1980

Incorporation of saturated and cis- and trans-unsaturated long chain fatty acids in rat myocytes and increased susceptibility to arrhythmias.

Neonatal rat heart myocytes cultured for 3 days in fatty acid-enriched (5 X 10(5) M stearate, oleate, elaidate, linoleate, linoelaidate or arachidonate at a 3 : 1, fatty acid (FA/albumin ratio) were analyzed by high-pressure liquid chromatography (HPLC) for the FA content of their neutral lipid, glyco-cardiolipid and phospholipid fractions and were tested for their susceptibility to arrhythmias produced by hypoxic/normoxic medium changes. Increases in the relative amount of FA in the above lipid fractions were generally in the order: elaidate = linoelaidate greater than linoleate = arachidonate greater than stearate = oleate. Cell morphology was unaffected by such treatment, but the cultures were more susceptible to induced arrhythmias. Cultures enriched with trans-FA, elaidate or linoelaidate, became markedly arrhythmic; arrhythmias in stearate-enriched cultures were of short duration; whereas the other FA produced intermediate increases. Susceptibility to arrhythmias could not be correlated with polyunsaturated fatty acid (PUFA/saturated fatty acid (SATFA) ratios of FA in the phospholipid fraction.

Animals↗
PubMed1995

Replacing cis octadecenoic acid with trans isomers in media containing rat adipocytes stimulates lipolysis and inhibits glucose utilization.

On the basis of earlier reports of reduced growth rate and fat accumulation in animals fed trans 18:1, a study was conducted to determine whether the effects of trans 18:1 on lipolysis and glucose utilization by adipocytes differed from effects of the cis isomer. Two experiments compared three fatty acid isomers (oleic, elaidic and vaccenic acids) at several concentrations and at several fatty acid to albumin ratios in cell media. Adipocytes were isolated from adipose tissue of rats by collagenase digestion and incubated for 2 h in media containing added fatty acids. Compared with oleic acid, both trans isomers reduced (P < 0.01) the amount of glucose converted to cell lipid in both experiments. Glucose oxidation to carbon dioxide also was lower for both trans fatty acids in Experiments 1 (P < 0.05) and 2 (P < 0.06). Lipolytic rates were increased (P < 0.01) in both experiments by replacing oleic acid with either of the trans isomers. Trans isomers of octadecenoic acid had catabolic effects on adipocyte metabolism that occurred regardless of the position of the double bond, the fatty acid concentration in media or the fatty acid to albumin ratio. These catabolic effects explain previous observations of reduced growth rate and fat accumulation when oleic acid in animal diets is replaced with a trans isomer.

Adipocytes↗
PubMed2005

Trans lipids: the free radical path.

Free radical-catalyzed cis-trans isomerization of unsaturated lipids and its outcome in biomimetic conditions are reviewed. They provided indications for an endogenous origin of trans unsaturated fatty acids in humans by the attack of thiyl radicals. A multidisciplinary approach highlights the relevance of this topic. The role of cis lipid geometry and its maintenance in the biological environment is an emerging question, with future developments in the fields of lipidomics, biology, and medicine.

Free Radicals↗
PubMed2000

Assessment of individual fatty acid intake.

Dietary assessment of individual fatty acid intake is difficult due to a number of limitations. Information regarding the type, quantity and brand-name of fat used in cooking and at the table is required. In addition, margarine manufacturers may change the component oils used for reasons of cost, which changes the fatty acid composition of their products from season-to-season. Independent markers of fatty acid intake are required, therefore, to compensate for these limitations. Adipose tissue concentrations have been used as a measure of habitual intake of fatty acid groups and individual fatty acids in numerous studies. Saturated (SFA) and monounsaturated fatty acids (MUFA) are generally poorly correlated with adipose tissue concentrations, which can be explained partly by endogenous synthesis. In general, adipose tissue concentrations of exogenously-produced fatty acids (n-3 and n-6 polyunsaturated fatty acids (PUFA)) are well correlated with estimates of habitual intake. Correlations between dietary trans unsaturated fatty acids (TUFA) and adipose tissue concentrations vary between countries, which may be due to differences in dietary sources. Correlations may be affected by differences in bioavailability or selective retention of fatty acids in certain tissue lipids.

Adipose Tissue↗
PubMed1988

Membrane surface pressure can account for differential activities of membrane-penetrating molecules.

It is a common observation that cis-unsaturated and branched chain fatty acids, which are usually liquid, affect membrane function differently from saturated and trans-unsaturated fatty acids, which are usually solid. We also found that the former are much more potent than the latter in inhibiting viral hemolytic activity. A search for the origin of this difference revealed a correlation between inhibition and equilibrium surface pressure (the surface pressure at the air/water interface of a solution of the substance in question). Using a simple but rigorous thermodynamic analysis, we show that penetration of a lipid bilayer is correlated with equilibrium surface pressure of the penetrating molecule. We therefore conclude that an important reason for the difference in effects of liquid and solid fatty acids on membranes is the greater penetrability of the former relative to the latter. We suggest that attributing such effects to fluidity changes in the membrane should await demonstration of actual intramonolayer residence of the fatty acid in the membrane. The thermodynamic analysis is readily generalized and, in the absence of specific interactions between penetration and bilayer molecules, provides a convenient method for predicting membrane penetration by virtually any type of exogenous molecule.

Fatty Acids, Nonesterified↗
PubMed1996

Unusual fatty acids in the depot fat of the Canadian beaver (Castor canadensis).

Unusual fatty acids in the adipose tissue of the Canadian beaver were analysed by argentation thin-layer chromatography, gas-liquid chromatography and gas chromatography-mass spectrometry of several adducts and spectroscopic measurements. The total proportion of trans-octadecenoic fatty acids and the distribution of double bonds in these acids resembled those of ruminant fats. Because trans-11-18:1 was the main trans-18:1 isomer of beaver fat and a conjugated diene cis-9, trans-11-18:2 was also detected, it can be deduced that linoleic acid (cis-9, cis-12-18:2) is biohydrogenated in the beaver. The ideas that microbial processes intervene before normal absorption and fatty acid metabolism of the beaver is also supported by the larger amounts of anteiso odd-chain fatty acids with respect to the corresponding iso acids in the beaver depots. In addition, the distribution of double bonds in the cis-octadecenoic acids was wide, as it is in the depot fats of ruminants.

Adipose Tissue↗
PubMed1999

Effects of different forms of dietary hydrogenated fats on serum lipoprotein cholesterol levels.

BACKGROUND: Metabolic studies suggest that fatty acids containing at least one double bond in the trans configuration, which are found in hydrogenated fat, have a detrimental effect on serum lipoprotein cholesterol levels as compared with unsaturated fatty acids containing double bonds only in the cis configuration. We compared the effects of diets with a broad range of trans fatty acids on serum lipoprotein cholesterol levels. METHODS: Eighteen women and 18 men consumed each of six diets in random order for 35-day periods. The foods were identical in each diet, and each diet provided 30 percent of calories as fat, with two thirds of the fat contributed as soybean oil (<0.5 g of trans fatty acid per 100 g of fat), semiliquid margarine (<0.5 g per 100 g), soft margarine (7.4 g per 100 g), shortening (9.9 g per 100 g), or stick margarine (20.1 g per 100 g). The effects of those diets on serum lipoprotein cholesterol, triglyceride, and apolipoprotein levels were compared with those of a diet enriched with butter, which has a high content of saturated fat. RESULTS: The mean (+/-SD) serum low-density lipoprotein (LDL) cholesterol level was 177+/-32 mg per deciliter (4.58+/-0.85 mmol per liter) and the mean high-density lipoprotein (HDL) cholesterol level was 45+/-10 mg per deciliter (1.2+/-0.26 mmol per liter) after subjects consumed the butter-enriched diet. The LDL cholesterol level was reduced on average by 12 percent, 11 percent, 9 percent, 7 percent, and 5 percent, respectively, after subjects consumed the diets enriched with soybean oil, semiliquid margarine, soft margarine, shortening, and stick margarine; the HDL cholesterol level was reduced by 3 percent, 4 percent, 4 percent, 4 percent, and 6 percent, respectively. Ratios of total cholesterol to HDL cholesterol were lowest after the consumption of the soybean-oil diet and semiliquid-margarine diet and highest after the stick-margarine diet. CONCLUSIONS: Our findings indicate that the consumption of products that are low in trans fatty acids and saturated fat has beneficial effects on serum lipoprotein cholesterol levels.

Aged↗
PubMedDate not supplied

Methods for analysis of conjugated linoleic acids and trans-18:1 isomers in dairy fats by using a combination of gas chromatography, silver-ion thin-layer chromatography/gas chromatography, and silver-ion liquid chromatography.

Conjugated linoleic acids (CLA) are octadecadienoic acids (18:2) that have a conjugated double-bond system. Interest in these compounds has expanded since CLA were found to be associated with a number of physiological and pathological responses such as cancer, metastases, atherosclerosis, diabetes, immunity, and body fat/protein composition. The main sources of these conjugated fatty acids are dairy fats. Rumen bacteria convert polyunsaturated fatty acids, especially linoleic and linolenic acids, to CLA and numerous trans- containing mono- and diunsaturated fatty acids. It has been established that an additional route of CLA synthesis in ruminants and monogastric animals, including humans, occurs via delta9 desaturation of the trans-18:1 isomers. To date, a total of 6 positional CLA isomers have been found in dairy fats, each occurring in 4 geometric forms (cis,trans; trans,cis; cis,cis; and trans,trans) for a total of 24. All of these CLA isomers can be resolved only by a combination of gas chromatography (GC), using 100 m highly polar capillary columns, and silver-ion liquid chromatography, using 3 of these 25 cm columns in series. Complete analysis of all the trans-18:1 isomers requires prior isolation of trans monoenes by silver-ion thin-layer chromatography (TLC), followed by GC analysis using the same 100 m capillary columns operated at low temperatures starting from 120 degrees C. These analytical techniques are required to assess the purity of commercial CLA preparations, because their purity will affect the interpretation of any physiological and/or biochemical response obtained. Prior assessment of CLA preparations by TLC is also recommended to determine the presence of any other impurities. The availability of pure CLA isomers will permit the evaluation and analysis of individual CLA isomers for their nutritional and biological activity in model systems, animals, and humans. These techniques are also essential to evaluate dairy fats for their content of specific CLA isomers and to help design experimental diets to increase the level of the desired CLA isomers in dairy fats. These improved techniques are further required to evaluate the CLA profile in monogastric animals fed commercial CLA preparations for CLA enrichment of animal products. This is particularly important because absorption and metabolism will alter the ingested-CLA profile in the animal fed.

Animals↗
PubMed2006

Continuous enzymatic transesterification of sesame oil and a fully hydrogenated fat: effects of reaction conditions on product characteristics.

An immobilized lipase from Thermomyces lanuginosus (TL IM) was employed to mediate the continuous transesterification of sesame oil and fully hydrogenated soybean oil (FHSBO) in a packed-bed reactor operating at 70 degrees C. Reactions between sesame oil (rich in LLL (15.97%), LOL (31.56%), and OLO (21.15%) [L = linoleic; O = oleic]) and the fully hydrogenated fat ((73.7% SSS, 26.3% SPS) [S = stearic; P = palmitic]) produced semi-solid fats. These products are complex mixtures of triacylglycerol (TAG) species whose compositions depend on reaction conditions. The dependence of the steady state product TAG profile on space time was determined for four initial weight ratios of sesame oil to hydrogenated fat (90:10, 80:20, 70:30, and 60:40). Except for the trial involving a weight ratio of sesame oil to FHSBO of 60:40, near equilibrium conditions were achieved at space times of 30 min-1 h. The chemical, physical, and functional properties of the product semi-solid fats were characterized. The predominant TAG species in the quasi-equilibrium products obtained from the mixture initially containing 90% (w/w) sesame oil and 10% FHSBO were LOL (26.22%) and OLO (21.92%). For transesterification of 80% sesame oil and 20% FHSBO, the major product species were OOP (21.27%), LOL (17.46%), and OLO (13.93%). OOP (24.38%) was the major product for reaction of 70% sesame oil with 30% FHSBO. Appropriate choices of reaction conditions and initial ratios of sesame oil to FHSBO lead to TAG with melting profiles and solid fat contents (SFC) similar to those of a variety of commercial products.

Ascomycota↗
PubMed2001

Effect of fatty acids on phase behavior of hydrated dipalmitoylphosphatidylcholine bilayer: saturated versus unsaturated fatty acids.

The effect of some fatty acids on the phase behavior of hydrated dipalmitoylphosphatidylcholine (DPPC) bilayer was investigated with special interest in possible difference between saturated and unsaturated fatty acids. The phase behavior of hydrated DPPC bilayer was followed by a differential scanning calorimetry and a Fourier transform infrared spectroscopy. The addition of palmitic acid (PA) increased the bilayer phase transition temperature with the increase of the PA content in the mixture. In addition, DPPC molecules in gel phase bilayer became more rigid in the presence of PA compared with those in the absence of PA. This effect of PA on the phase behavior of hydrated DPPC bilayer is common to other saturated fatty acids, stearic acid, myristic acid, and also to unsaturated fatty acid with trans double bond, elaidic acid. Contrary to these fatty acids, oleic acid (OA), the unsaturated fatty acid with cis double bond in the acyl chain, exhibited quite different behavior. The effect of OA on the bilayer phase transition temperature was rather small, although a slight decrease in the temperature was appreciable. Furthermore, the IR spectral results demonstrated that the perturbing effect of OA on the gel phase bilayer of DPPC was quite small. These results mean that OA does not disturb the hydrated DPPC bilayer significantly.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

Arachidonic acid as a second messenger. Interactions with a GTP-binding protein of human neutrophils.

Arachidonic acid (20:4) and other cis-unsaturated fatty acids exert direct effects on a variety of cells, effects that do not depend on the metabolism of fatty acids via cyclooxygenase or lipoxygenase pathways. In these studies arachidonic acid and other cis-unsaturated fatty acids (but not trans-unsaturated or saturated fatty acids) increased the specific binding of the nonhydrolyzable analog of GTP, [35S]GTP gamma S, to purified neutrophil membrane preparations and elicited superoxide anion generation from intact neutrophils. There was a positive correlation (r = 0.70) between the capacity of fatty acids to increase nucleotide binding and to elicit the respiratory burst. Scatchard plot analysis of binding at equilibrium demonstrated an increase in the number of available GTP binding sites in the presence of 50 microM arachidonic acid. Nonsteroidal antiinflammatory agents interfered with the arachidonic acid effect on [35S]GTP gamma S binding. ADP-ribosylation of the pertussis toxin substrate Gi alpha within the plasmalemma-reduced specific [35S]GTP gamma S binding and blocked arachidonate-dependent enhancement of binding. Moreover, pertussis toxin treatment of intact neutrophils inhibited arachidonic acid-induced superoxide anion generation. The data indicate that arachidonic acid directly activates a GTP binding protein in the neutrophil plasma membrane and may thereby act as a second messenger in signal transduction.

Adenosine Triphosphate↗
PubMedDate not supplied

The influence of C18 fatty acids on the growth of a 3T6 derived cell line.

The effects of the 18 carbon chain length series of fatty acids on the viability of a 3T6 derived mouse fibroblast cell line were tested. An overall concentration dependent cytotoxic effect was demonstrated with the saturated fatty acid, and cis- and trans- mono- and dienoic fatty acids; however, within a narrow range of concentrations, cell growth was stimulated. As a result of the increase in cell viability over this concentration range, more than one ID50 value is calculable. The most dramatic cytotoxic effects were shown by cis-C18:3 omega 3 and cis-C18:3 omega 6 with ID50 values of +/- 30 micrograms/ml. cis-C18:4 omega 3 showed an initial cytotoxic effect at fatty acid concentrations of 0-20 micrograms/ml, whilst with fatty acid concentrations of 20-100 mg/ml a cytostatic effect was observed. Furthermore, the effects observed do not appear to be dependent upon the 48 hour incubation period or the presence of fetal bovine serum, and thus would seem to be related to the changes in free fatty acid concentration.

Animals↗
PubMed2006

Facts on fats.

Cardiovascular disease and age-related macular degeneration (AMD) may share common risk factors in their causal pathways. Decades of research from the cardiovascular sciences on fats have led investigators to focus on specific types of fats rather than total fat as a whole. They have established that saturated and trans-unsaturated fats (trans fats) are damaging to cardiovascular health while polyunsaturated fats, particularly the marine omega 3 fatty acids appear protective. This has led to a number of studies investigating the associations of fat and AMD. Though the causal relationship between fats and AMD remain unproven, some studies suggest that an association may be present. To be able to understand and interpret the study results and their implications, an understanding of the fats in the diet is important. This review aims to give an overview of fatty acids, particularly the trans-unsaturated fatty acids, and the relevant food groups.

Dietary Fats↗
PubMed2005

Cis-trans isomerase gene in psychrophilic Pseudomonas syringae is constitutively expressed during growth and under conditions of temperature and solvent stress.

In a recent study, we established that psychrophilic Pseudomonas syringae (Lz4W) requires trans-monounsaturated fatty acid for growth at higher temperatures (Kiran et al. in Extremophiles, 2004). It was also demonstrated that the cti gene was highly conserved and exhibited high sequence identity with cti of other Pseudomonas spp. (Kiran et al. in Extremophiles, 2004). Therefore it would be interesting to understand the expression of the cti gene so as to unravel the molecular basis of adaptation of microorganisms to high temperature. In the present study, the expression of cti was monitored by RT-PCR analysis during different growth stages and under conditions of high temperature and solvent stress in P. syringae. Results indicated that the cti gene is constitutively expressed during different stages of growth and the transcript level is unaltered even under conditions of temperature and solvent stress implying that the observed increase in trans-monounsaturated fatty acids (Kiran et al. in Extremophiles, 2004) is not under transcriptional control. A putative promoter present in the intergenic region of the metH and cti gene has also been characterized. The translation start site ATG, the Shine-Dalgarno sequence AGGA and the transcription start site "C" were also identified. These results provide evidence for the first time that the cti gene is constitutively expressed under normal conditions of growth and under conditions of temperature and solvent stress thus implying that the Cti enzyme is post-transcriptionally regulated.

Base Sequence↗
PubMed1981

cis-Unsaturated fatty acids induce the fusion of chromaffin granules aggregated by synexin.

When isolated chromaffin granules were aggregated by synexin (a Ca2+-binding protein present in chromaffin and other secretory tissues) and then exposed to cis-unsaturated fatty acids at 37 degrees C, they fused together to form large vesicles. The fusion was monitored by phase and electron microscopy and by turbidity measurements on the granule suspension. Arachidonic acid was the most effective fusogen, whereas trans-unsaturated fatty acids, saturated fatty acids, detergents or lysolecithin were inactive. During fusion some of the epinephrine of the granules was released but the soluble core proteins remained trapped in the resulting vesicles. These vesicles swelled to enclose the maximum volume. Although this swelling could be inhibited by increasing the osmotic strength of the medium, it did not appear to depend on the chemiosmotic properties of the granule membranes as it was not influenced by ATP, a proton ionophore, or an anion transport inhibitor. The regulators of this in vitro fusion--Ca2+, synexin, and free, cis-unsaturated fatty acids--may be present in the cytoplasm of the chromaffin cell when it is stimulated to release epinephrine and granule proteins by exocytosis. Therefore, this fusion event may be the same that occurs between chromaffin granules undergoing compound exocytosis.

Animals↗
PubMed2005

Modulation of native T-type calcium channels by omega-3 fatty acids.

Low voltage-activated, rapidly inactivating T-type Ca(2+) channels are found in a variety of cells where they regulate electrical activity and Ca(2+) entry. In whole-cell patch clamp recordings from bovine adrenal zona fasciculata cells, cis-polyunsaturated omega-3 fatty acids including docosahexaenoic acid (DHA), eicosapentaenoic acid, and alpha-linolenic acid inhibited T-type Ca(2+) current (I(T-Ca)) with IC(50)s of 2.4, 6.1, and 14.4microM, respectively. Inhibition of I(T-Ca) by DHA was partially use-dependent. In the absence of stimulation, DHA (5microM) inhibited I(T-Ca) by 59.7+/-8.1% (n=5). When voltage steps to -10mV were applied at 12s intervals, block increased to 80.5+/-7.2%. Inhibition of I(T-Ca) by DHA was accompanied by a shift of -11.7mV in the voltage dependence of steady-state inactivation, and a smaller -3.3mV shift in the voltage dependence of activation. omega-3 fatty acids also selectively altered the gating kinetics of T-type Ca(2+) channels. DHA accelerated T channel recovery from inactivation by approximately 3-fold, but did not affect the kinetics of T channel activation or deactivation. Arachidonic acid, an omega-6 polyunsaturated fatty acid, also inhibited T-type Ca(2+) current at micromolar concentrations, while the trans polyunsaturated fatty acid linolelaidic acid was ineffective. These results identify cis polyunsaturated fatty acids as relatively potent, new T-type Ca(2+) channel antagonists. omega-3 fatty acids are essential dietary components that have been shown to possess remarkable neuroprotective and cardioprotective properties that are likely mediated through suppression of electrical activity and associated Ca(2+) entry. Inhibition of T-type Ca(2+) channels in neurons and cardiac myocytes could contribute significantly to their protective actions.

Adrenal Glands↗