linoleic-acid and 9-11-linoleic-acid

A meta-analysis was conducted using the results of 82 experiments (78 publications, 266 treatments) to investigate the importance of dietary C18 fatty acids (FA) and feeding regimen for milk C18 FA profile and apparent recovery of selected FA relative to intake of these FA or their precursors. Feeding treatments based on lipid-supplemented diets were excluded. Feeding regimens were defined as grazing [including partial and full-time grazing, at dietary concentrate proportions from 0 to 44% dry matter (DM)], forage-based indoor feeding [>65% forage of total DM intake (DMI)], and concentrate-based indoor feeding (forage DMI ≤65% of DMI). Linoleic acid (LLA), α-linolenic acid (ALA), and total C18 FA proportions in milk fat increased linearly with the respective dietary FA content in all feeding regimens tested. This effect was highest in the forage-based indoor feeding. Slopes were lowest for the grazing regimens, especially regarding ALA and the sum of all C18 FA, whereas the intercepts of the prediction equations of milk ALA and total C18 FA proportions were highest for grazing regimens. This indicates that, in grazing cows, factors other than dietary FA contents determine the C18 FA composition of the milk fat. At equal dietary LLA contents, the type of feeding regimen showed no significant effect on LLA proportion in milk fat. Milk fat proportions of rumenic acid and vaccenic acid were positively related to the sum of dietary ALA and LLA contents. Grazing regimens led to the strongest enrichment of rumenic acid and vaccenic acid in milk fat. The apparent recovery of ALA, LLA, and total C18 FA (secreted, % of intake), an estimate for transfer efficiency, decreased with increasing dietary content. This relationship followed a nonlinear decay function. When the dietary content of these FA exceeded a certain threshold (about 0.2, 0.8, and 2.8% of DM for ALA, LLA, and total C18 FA, respectively) the recovery in milk remained constant at about 5, 10, and 82% of the ingested ALA, LLA, and total C18 FA, respectively. At dietary proportions below 0.01% ALA and 1.5% total C18 FA of DM, their apparent recovery in milk fat exceeded 100%. In conclusion, a general inverse relationship between dietary C18 FA and the corresponding apparent recovery in milk fat seems to exist. Within this frame, the effect of different types of feeding regimens on the eventual milk C18 FA profile varies. Among them, grazing pasture appears to provide the most variable properties.

Topics: alpha-Linolenic Acid; Animal Feed; Animals; Cattle; Diet; Dietary Fats; Fatty Acids, Unsaturated; Linear Models; Linoleic Acid; Linoleic Acids, Conjugated; Milk

Conjugated Linoleic Acids (CLA) are of great interest for analysts since techniques have been developed to determine the dietary occurrence of CLA with a good accuracy. CLA is found in animal products from ruminant sources as the result of biohydrogenation of polyunsaturated fatty acids in the rumen and as the consequence of the delta-9 desaturation of vaccenic acid in animal tissues. CLA can also be obtained in the laboratory by isomerisation of linoleic acid or by total chemical synthesis. While the "natural" isomer is rumenic acid (9c,11t-18:2), synthetic mixtures contain mainly two isomers: the 9c,11t- and the 10t,12c-18:2. Although CLA have been shown to be metabolized into desaturated and chain elongated products, it remains unclear whether these so-formed conjugated metabolites may be involved in the effects of CLA on fatty acid metabolism. Experiments carried out on animal models with CLA have shown different health benefits: anticarcinogenic, antiatherosclerotic effects, modulation of body composition , the "natural" CLA (9c,11t-18:2) being closely related to the protection against cancer and the 10t,12c-18:2 to the reduction of the fat mass. Nevertheless, recent findings have suggested adverse effects in mice. Most of the studies carried out on humans concern the influence of CLA on body composition and its possible inverse association with cancer. Since the results are still controversial and since very few data dealing with the safety of using CLA in long term feeding studies have so far been published, further works are warranted to consider the benefits of CLA for humans.

Topics: Animals; Arteriosclerosis; Body Composition; Disease Models, Animal; Humans; Linoleic Acid; Linoleic Acids, Conjugated; Neoplasms; Oleic Acids; Trans Fatty Acids

The objective of this study was to examine the effect of ruminal pulse dose of free linoleic acid (LA) and free docosahexaenoic acid (DHA) on microbial populations in the rumen, duodenal fatty acid (FA) flow, milk composition, and milk FA profiles of Chinese Holstein dairy cows. Four rumen- and duodenal-fistulated Chinese Holstein cows in mid lactation (138.5 ± 10d in milk) were randomly assigned to 3 treatment groups and 1 control group in a 4 × 4 Latin square design over 4 periods (3 wk per period). Diets contained either no LA or 2.7% LA and either no DHA or 0.5% DHA in a 2 × 2 factorial arrangement of treatments. Ruminal pulse dose with DHA increased counts of Megasphaera elsdenii, decreased Fibrobacter succinogenes, but did not affect Butyrivibrio fibrisolvens or Ruminococcus flavefaciens. The pulse dose of LA at 2.7% dry matter had no effect on the population sizes of the 3 major cellulolytic bacterial species or M. elsdenii, and no interaction was observed between LA and DHA. The pulse dose of LA or DHA, either alone or in combination, increased the duodenal flow of vaccenic acid (VA). The milk VA and cis-9,trans-11 conjugated linoleic acid (CLA) contents also increased in response to the fatty acid pulse dose, and the pulse dose of both LA and DHA together had the most profound stimulatory effect. This study indicated that ruminal pulse dose of LA or DHA could be used to increase duodenal flow of VA and the milk contents of potentially health-promoting FA, such as VA and cis-9,trans-11 CLA. These results might be useful in formulating dietary interventions to improve milk cis-9,trans-11 CLA contents.

Topics: Animals; Cattle; Diet; Docosahexaenoic Acids; Duodenum; Female; Lactation; Linoleic Acid; Linoleic Acids, Conjugated; Milk; Oleic Acids; Rumen

1. Diene-conjugated fatty acids are one of the products of free-radical attack upon lipids and therefore have been used as markers of such attack. The major diene-conjugated fatty acid in human tissue and serum is an isomer of linoleic acid (9,12-octadecadienoic acid), namely 9,11-octadecadienoic acid. Diet may be another source of this isomer, raising questions as to its value as a free-radical marker. The aim of this study was to determine the importance of diet as a source of 9,11-octadecadienoic acid in phospholipid esterified fatty acids in human serum. 2. Foodstuffs rich in 9,11-octadecadienoic acid were identified. Fourteen subjects volunteered to alter their diets, either increasing ('high diet') or decreasing ('low diet') their intake of these foodstuffs for 3 weeks. Where subjects undertook both diets, a washout period of at least 3 weeks was allowed between phases. 3. Seven-day diet histories were kept and scored with respect to their content of 9,11-octadecadienoic acid. The concentrations of 9,11-octadecadienoic acid and linoleic acid in serum phospholipids were measured by h.p.l.c. with u.v. detection. 4. The percentage molar ratio of 9,11-octadecadienoic acid to linoleic acid was calculated. The percentage molar ratio rose significantly on the 'high diet' [1.3(0.4) versus 1.9(0.7), P = 0.01, mean (SD)] and fell significantly on the 'low diet' [1.6(0.4) versus 1.1(0.4), P = 0.004, means (SD)]. There was a significant correlation between the change in dietary intake of 9,11-octadecadienoic acid and the change in the percentage molar ratio (r = 0.829, P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Diet; Fatty Acids, Unsaturated; Female; Free Radicals; Humans; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Male; Phospholipids

Two common conjugated linoleic acids (LAs), cis-9, trans-11 CLA (c9,t11 CLA) and trans-10, cis-12 CLA (t10,c12 CLA), exert various biological activities. However, the effect of CLA on the generation of neurotoxic amyloid-β (Aβ) protein remains unclear. We found that c9,t11 CLA significantly suppressed the generation of Aβ in mouse neurons. CLA treatment did not affect the level of β-site APP-cleaving enzyme 1 (BACE1), a component of active γ-secretase complex presenilin 1 amino-terminal fragment, or Aβ protein precursor (APP) in cultured neurons. BACE1 and γ-secretase activities were not directly affected by c9,t11 CLA. Localization of BACE1 and APP in early endosomes increased in neurons treated with c9,t11 CLA; concomitantly, the localization of both proteins was reduced in late endosomes, the predominant site of APP cleavage by BACE1. The level of CLA-containing phosphatidylcholine (CLA-PC) increased dramatically in neurons incubated with CLA. Incorporation of phospholipids containing c9,t11 CLA, but not t10,c12 CLA, into the membrane may affect the localization of some membrane-associated proteins in intracellular membrane compartments. Thus, in neurons treated with c9,t11 CLA, reduced colocalization of APP with BACE1 in late endosomes may decrease APP cleavage by BACE1 and subsequent Aβ generation. Our findings suggest that the accumulation of c9,t11 CLA-PC/LPC in neuronal membranes suppresses the production of neurotoxic Aβ in neurons.

Topics: Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Cells, Cultured; Dietary Supplements; Endosomes; Immunohistochemistry; Linoleic Acid; Linoleic Acids, Conjugated; Male; Mice; Mice, Inbred C57BL; Neurons; Phosphatidylcholines

Lactobacillus plantarum YW11 capability to convert linoleic acid into conjugated linoleic acid and other metabolites was studied in a dose-dependent manner by supplementing LA at different concentrations. L. plantarum YW11 displayed a uniform distinctive growth curve of CLA and other metabolites at concentrations of LA ranging from 1% (w/v) to 10% (w/v), with slightly increased growth at higher LA concentrations. The biotransformation capability of L. plantarum YW11 evaluated by GC-MS revealed a total of one CLA isomer, i.e. 9-cis,11-trans-octadecadienoic acid, also known as the rumenic acid (RA), one linoleic acid isomer (linoelaidic acid), and LA metabolites: (E)-9-octadecenoic acid ethyl ester, trans, trans-9,12-octadecadienoic acid, propyl ester and stearic acid. All the metabolites of linoleic acid were produced from 1 to 10% LA supplemented MRS media, while surprisingly the only conjugated linoleic acid compound was produced at 10% LA. To assess the presence of putative enzymes, responsible for conversion of LA into CLA, in silico characterization was carried out. The in silico characterization revealed presence of four enzymes (10-linoleic acid hydratase, linoleate isomerase, acetoacetate decarboxylase and dehydrogenase) that may be involved in the production of CLA (rumenic acid) and LA isomers. The biotransformation ability of L. plantarum YW11 to convert LA into RA has great prospects for biotechnological and industrial implications that could be exploited in the future scale-up experiments.

Topics: Biotransformation; Computer Simulation; Food Microbiology; Gas Chromatography-Mass Spectrometry; Humans; Isomerism; Lactobacillus plantarum; Linoleic Acid; Linoleic Acids, Conjugated

The protozoal fatty acid (FA) composition and community structure are important to dairy cattle nutrition and their products. The purpose of the study was to observe if the rumen protozoal FA profiles and protozoal community structure differed by breed and lactation stage. At 93, 183, and 273 days in milk (DIM), whole rumen digesta samples were collected from seven co-housed Holstein (H), eight Jersey (J), and seven Holstein-Jersey crossbreed (C) cows. Rumen protozoal linoleic acid was higher at 183 DIM (8.1%) and 273 DIM (8.3%) than at 93 DIM (5.7%). Oleic acid was the most abundant protozoal unsaturated FA (10.1%). Protozoal rumenic acid and protozoa of the genus Metadinium were higher in J (9.9%) than in H (0.52%) and C (0.96%). Protozoa belonging to the genus Entodinium were more abundant in H (45.2%) than in J (23.4%) and C (30.2%). In conclusion, breed and DIM affected several protozoal FAs and genera.

Topics: Animals; Breeding; Cattle; Ciliophora; DNA, Protozoan; Fatty Acids; Female; Lactation; Linoleic Acid; Linoleic Acids, Conjugated; Oleic Acid; Parity; Polymerase Chain Reaction; RNA, Ribosomal, 18S; Rumen; Species Specificity

Ricinoleic acid (RA; 12-hydroxy-cis-9-18:1) is the main fatty acid component of castor oil. Although a precursor for CLA synthesis in lactic acid bacteria, RA was found previously not to form CLA in ruminal digesta but to have some inhibitory properties. The present study was undertaken to evaluate the potential of RA to modulate ruminal biohydrogenation and methanogenesis. Ruminal digesta from 4 sheep receiving a mixed hay-concentrate diet was incubated in vitro with 0.167 g/L of linoleic acid (LA; cis-9,cis-12-18:2) or with a combination of LA and RA or LA and castor oil (LA, RA, and castor oil added to a final concentration of 0.167 g/L) in the presence and absence of lipase. The CLA rumenic acid (cis-9,trans-11-18:2) accumulated when either RA or castor oil and lipase was present. Vaccenic acid (VA; trans-11-18:1) also accumulated, and a decrease of the rate of production of stearic acid (SA; 18:0) was observed. When LA was incubated with castor oil in the absence of lipase, no effects on biohydrogenation were observed. Ricinoleic acid at 0.02 g/L did not affect growth of Butyrivibrio fibrisolvens but it inhibited growth of Butyrivibrio proteoclasticus. Butyrivibrio proteoclasticus but not B. fibrisolvens metabolized RA to 12-hydroxystearate. Linoleic acid metabolism by B. proteoclasticus appeared to be unaffected by RA addition whereas rumenic acid accumulation increased (P = 0.015 at 12 h) when RA was added. A 28% decrease (P = 0.004) in methane was obtained in 24 h in vitro incubations of diluted buffered ruminal fluid with added 0.2 g RA/L. There was no effect on the total concentration of VFA after 24 h as a result of RA addition, but the molar proportions of acetate and butyrate were decreased (P = 0.041 and P < 0.001, respectively) whereas that of propionate increased (P < 0.001). It was concluded that, at least in vitro, RA or the combination of castor oil and lipase inhibit biohydrogenation, causing the accumulation of rumenic acid and VA, with potential health benefits for ruminant products. The effect appeared to be mediated via an inhibitory effect on the biohydrogenating activity of B. proteoclasticus. An added environmental benefit could be a concomitant decrease in methane emissions. In vivo studies are now required to confirm the potential of these additives.

Topics: Animals; Butyrivibrio; Castor Oil; Diet; Fatty Acids, Volatile; Gastrointestinal Contents; Hydrogenation; Linoleic Acid; Linoleic Acids, Conjugated; Methane; Oleic Acids; Propionibacterium acnes; Ricinoleic Acids; Rumen; Sheep, Domestic; Species Specificity

A simple and accurate method for screening of bacterial strains with the ability to convert free linoleic acid into specific conjugated linoleic acid (CLA) isomers has been developed by combining the ultraviolet spectral scan and capillary electrophoresis analysis. The ultraviolet spectral scan was carried out for preliminary screening of bacterial strains with the capacity to biosynthesize CLA, and the absorption peak at 228-235 nm was used for assessing the possible production of CLA by bacteria. The capillary electrophoresis analysis was used as the follow-up confirmation to definitively conclude CLA production and the composition of CLA isomers. Linoleic acid at the concentration of 25 μg/mL, which showed little inhibitory effect on the growth of bacteria, was used for initial screening of CLA-producing strains. The strains with the ability to produce specific CLA isomers can be selected quickly from a large number of bacteria by this high-throughput method.

Topics: Bacteria; Electrophoresis, Capillary; High-Throughput Screening Assays; Isomerism; Linoleic Acid; Linoleic Acids, Conjugated; Molecular Biology; Spectrophotometry, Ultraviolet

Digesta samples from the ovine rumen and pure ruminal bacteria were incubated with linoleic acid (LA) in deuterium oxide-containing buffer to investigate the mechanisms of the formation of conjugated linoleic acids (CLAs). Rumenic acid (RA; cis-9,trans-11-18:2), trans-9,trans-11-18:2, and trans-10,cis-12-18:2 were the major CLA intermediates formed from LA in ruminal digesta, with traces of trans-9,cis-11-18:2, cis-9,cis-11-18:2, and cis-10,cis-12-18:2. Mass spectrometry indicated an increase in the n+1 isotopomers of RA and other 9,11-CLA isomers, as a result of labeling at C-13, whereas 10,12 isomers contained minimal enrichment. In pure culture, Butyrivibrio fibrisolvens and Clostridium proteoclasticum produced mostly RA with minor amounts of other 9,11 isomers, all labeled at C-13. Increasing the deuterium enrichment in water led to an isotope effect, whereby (1)H was incorporated in preference to (2)H. In contrast, the type strain and a ruminal isolate of Propionibacterium acnes produced trans-10,cis-12-18:2 and other 10,12 isomers that were minimally labeled. Incubations with ruminal digesta provided no support for ricinoleic acid (12-OH,cis-9-18:1) as an intermediate of RA synthesis. We conclude that geometric isomers of 10,12-CLA are synthesized by a mechanism that differs from the synthesis of 9,11 isomers, the latter possibly initiated by hydrogen abstraction on C-11 catalyzed by a radical intermediate enzyme.

Topics: Animals; Bacteria; Deuterium Oxide; Fatty Acids; Gastrointestinal Tract; Isomerism; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Models, Biological; Protein Isoforms; Ruminants; Sheep; Time Factors

To study the effects of c9, t11-conjugated linoleic acid (c9, t11-CLA) on the critical enzyme (COX-2) and its product - prostaglandin E2 (PGE2) of linoleic acid metabolism path in human gastric adenocarcinoma cell line (SGC-7901).. Expression of COX-2 mRNA and protein were measured by reverse transcription polymerase chain reaction (RT-PCR) and Western blot, PGE2 was determined by radioimmunoassay (RIA).. At the concentrations of 25, 50, 100, 200 pmol/L, c9, t11-CLA suppressed the expression of COX-2 mRNA, protein and PGE.. COX-2 is involved anti-cancer action of c9, t11-CLA and is likely to act as an important target.

Topics: Adenocarcinoma; Cell Line, Tumor; Cell Proliferation; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Dinoprostone; Humans; Linoleic Acid; Linoleic Acids, Conjugated; RNA, Messenger; Stomach Neoplasms

Two experiments were undertaken to evaluate the effect on milk and cheese fatty acid composition of feeding different fresh forages to dairy sheep both in winter (experiment 1, growing stage of the forages, early lactating ewes) and in spring (experiment 2, reproduction stage of the forages, midlactating ewes). Four forage species were compared: annual ryegrass (RY, Lolium rigidum Gaudin), sulla (SU, Hedysarum coronarium L.), burr medic (BM, Medicago polymorpha L.), and a daisy forb (CH, Chrysanthemum coronarium L.). The forages were cut twice daily and offered ad libitum to 4 replicate groups of Sarda dairy sheep (groups RY, SU, BM, and CH). The CH forage was particularly rich in linoleic acid in both periods, whereas BM and SU forages were rich in linolenic acid in winter and spring, respectively. Milk fatty acid composition was affected by the forage in both experiments. Milk conjugated linoleic acid and vaccenic acid contents were higher in CH and BM groups (winter) and CH group (spring) than in the other groups. No differences were observed when comparing fatty acid profile between milk, 1-d-old cheeses, and 60-d-old cheeses within experimental groups, suggesting that the fatty acid recovery rates during cheese making and ripening were not affected by the feeding regimens. After stepwise discriminant analyses of the pooled data, the milks and cheeses sourced in the different feeding regimens differed among them. Based on these results, we conclude that it is possible to manipulate the fatty acid profile of sheep dairy produce to maximize the content of beneficial fatty acids by the use of appropriate fresh forage-based regimens.

Topics: alpha-Linolenic Acid; Animals; Cheese; Chrysanthemum; Diet; Fabaceae; Fatty Acids; Female; Food Handling; Lactation; Linoleic Acid; Linoleic Acids, Conjugated; Lolium; Medicago; Mediterranean Region; Milk; Oleic Acids; Seasons; Sheep

Conjugated linoleic acid (CLA), an anticarcinogenic compound with numerous other health benefits, is present mainly in dairy and beef lipids. The main CLA isomer present in dairy and beef lipids is cis 9, trans 11 CLA at a 0.5% concentration. The typical minimum human dietary intake of CLA is 10 times less than the 3 g/d suggested requirement that has been extrapolated from animal and cell-line studies. The objectives of this study were to produce CLA isomers from soybean oil by photoisomerization of soybean oil linoleic acid and to study the oxidation status of the oil. Refined, bleached, and deodorized soybean oil with added iodine concentrations of 0, 0.1, 0.25, and 0.5% was exposed to a 100-W mercury lamp for 0 to 120 h. An SP-2560 fused-silica capillary GC column with FID was used to analyze the esterified CLA isomers in the photoisomerized oil. The CLA content of the individual isomers was optimized by response surface methodology. Attenuated total reflectance (ATR)-FTIR spectra in the 3400 to 3600 cm(-1) range and 1H NMR spectra in the 8 to 12 ppm range of the photoisomerized soybean oil were obtained to follow hydroperoxide formation. The largest amount of cis 9, trans 11 CLA isomer in soybean oil was 0.6%, obtained with 0.25% iodine and 84 h of photoisomerization. Lipid hydroperoxide peaks in the ATR-FTIR spectra and aldehyde peaks in the 1H NMR spectra were not observed in the photoisomerized soybean oil, and the spectra were similar to that of fresh soybean oil. This study shows that CLA isomers can be produced simply and inexpensively from soybean oil by photoisomerization.

Topics: Hydrogen Peroxide; Isomerism; Linoleic Acid; Linoleic Acids, Conjugated; Photochemistry; Soybean Oil; Spectrum Analysis

Conjugated linoleic acid (CLA) isomers are potent inhibitors of mammary tumor cell growth. Evidence suggests that CLA modulates essential fatty acid (EFA) metabolism; however, it is not clear which parts of this pathway are important regulatory points modulated by CLA. Enriched mixtures of D9-cis,11-trans (D9c,11t)- and D10-trans,12-cis (D10t,12c)-18:2 were used to assess outcome measures of EFA metabolism pertaining to membrane phospholipid incorporation, tumor cell growth, and prostaglandin E2 (PGE2) synthesis in the MDA-MB-231 mammary tumor cell line. Tumor cells were treated with linoleic acid (LA), an equal mixture (Mix), or enriched preparations of D9c,11t- or D10t,12c-18:2. Treatment with Mix or the enriched mixture of D10t,12c-18:2 significantly inhibited the synthesis of arachidonic acid (AA) from LA, resulting in increased levels of LA and decreased levels of AA in membrane phosphatidylcholine and phosphatidylethanolamine (P < 0.05). LA and AA levels were not altered in cells treated with enriched D9c,11t-18:2 and were similar to those in LA control treated cells. All CLA treatments reduced [3H]thymidine uptake, an indicator of tumor cell growth, by more than one-half relative to LA controls. MDA-MB-231 cells challenged with AA in the presence of all CLA mixtures resulted in significantly reduced PGE2 synthesis relative to controls treated with LA (P < 0.05). It is evident that individual isomers exert inhibitory effects at specific steps of EFA metabolism, which correspondingly leads to a reduction in PGE2 synthesis and, ultimately, tumor growth.

Topics: Analysis of Variance; Arachidonic Acid; Breast Neoplasms; Dinoprostone; Female; Glycerophospholipids; Humans; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Stereoisomerism; Time Factors; Tumor Cells, Cultured

Lipid peroxidation, as measured by the thiobarbituric acid test, has been reported to have increased in hemodialysis (HD) patients, even though the test has low specificity in vivo. Conjugated diene fatty acid (CDFA) hydroperoxides are formed during lipid peroxidation, but not all conjugated dienes (CD) detected in humans originate from lipid peroxidation: octadeca-9,11-dienoic acid, a nonhydroperoxide CD derivative of linoleic acid (CDLA), has a dietary origin. We evaluated CDFA hydroperoxides, CDLA and linoleic acid, using high-performance liquid chromatography, in lipids extracted from plasma, adipose tissue and RBC membranes obtained from 25 patients treated with HD, 16 patients treated with hemodiafiltration (HDF) and 29 controls. No differences in the levels of CDFA hydroperoxides and linoleic acid were seen in any of the groups. Concentrations of CDLA were found to be significantly high in the adipose tissue and low in the RBC membranes of HD patients. HDF-treated patients showed the same results as HD patients. No direct evidence of increased lipid peroxidation was found in HD patients. This does not exclude the possibility that lipid peroxidation is increased and escapes direct detection due to the body's homeostatic control eliminating the increased production of hydroperoxides. Both HD- and HDF-treated patients showed a significant change in CDLA concentrations, either in the adipose tissue, or in the RBC membranes. These dietary CD may be mistaken for markers of lipid peroxidation by conventional methodologies.

Topics: Adipose Tissue; Chromatography, High Pressure Liquid; Erythrocyte Membrane; Free Radicals; Humans; Kidney Failure, Chronic; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Lipid Peroxidation; Lipid Peroxides; Middle Aged; Plasma; Regression Analysis; Renal Dialysis; Thiobarbituric Acid Reactive Substances

The diene conjugated linoleic acid isomer is currently used as an assay of free radical activity, but recent studies have cast doubt on the specificity of the assay. Therefore, 180 strains of common bacterial lung pathogens were studied to determine whether they could produce the diene conjugated isomer of linoleic acid in vitro. The various strains were grown in tissue culture fluid spiked with linoleic acid. Concentrations of the diene conjugated 18:2 [9,11] linoleic acid isomer and the parent compound, 18:2 [9,12] linoleic acid were then determined using a high performance liquid chromatography method. The percentage molar ratio of these two isomers was found to be significantly elevated in 12.8% of all bacterial strains examined. In contrast the thiobarbituric acid reactivity, a non-specific measure of lipid peroxidation, was not elevated in any of the strains incubated in an identical fashion. These results suggest that the diene conjugated linoleic assay may not be a reliable marker of the free radical processes in the lung in the presence of certain bacterial infections.

Topics: Bacteria; Biomarkers; Chromatography, High Pressure Liquid; Culture Media; Free Radicals; Humans; Isomerism; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Respiratory Tract Infections; Spectrophotometry, Ultraviolet; Thiobarbituric Acid Reactive Substances

Free-radical generation after successful thrombolysis in acute myocardial infarction may jeopardize ischaemic but viable myocardium, thus limiting the optimal benefits of reperfusion.. Circulating free-radical activity was assessed in 25 consecutive patients with acute myocardial infarction. Those who successfully reperfused (Group A) were compared with those who did not (Group B). We also compared patients who had or had not developed Q waves and patients with and without previous angina or myocardial infarction. All patients presented within 6 h of the onset of chest pain and received standard intravenous streptokinase therapy. Free-radical activity in serial serum samples collected over 72 h was measured using the percentage molar ratio (PMR) of the concentrations of 9,11-linoleic acid to 9,12-linoleic acid, and malonaldehyde concentration.. Throughout the study period Group A (n = 11) showed significantly greater change in serum PMR and malonaldehyde levels compared with Group B (n = 14) (P < 0.01). PMR differences between the two groups were most pronounced at 3 and 12 h (P < 0.001). Patients with non-Q-wave myocardial infarction (n = 5) showed significantly greater changes in serum PMR and malonaldehyde levels (P < 0.01) compared with those with Q-wave infarction (n = 20). A history of previous infarction or angina had no apparent effects on the changes in serum free-radical activity.. Successful early reperfusion and non-Q-wave myocardial infarction are both associated with a significantly greater increase in the levels of markers of serum free-radical activity immediately after infarction. The results support present concepts of free-radical-mediated reperfusion injury. Use of these assays may identify those patients who may be at risk from free-radical-mediated reperfusion injury.

Topics: Aged; Biomarkers; Female; Free Radicals; Humans; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Male; Malondialdehyde; Middle Aged; Myocardial Infarction; Myocardial Reperfusion Injury; Thrombolytic Therapy; Treatment Outcome

Linoleic acid (18:2(9,12)) and its diene-conjugated isomer (18:2(9,11)) were measured in 65 cervical biopsy samples. Both the 18:2(9,11) concentration and the 18:2(9,11)/18:2(9,12) molar ratio showed highly significant differences between the normal and precancerous groups. Both showed a further significant increase in 4 invasive carcinomas. The findings in histologically normal areas from organs with precancer correlated significantly with the results in the precancerous lesions.

Topics: Biopsy; Chromatography, High Pressure Liquid; Female; Free Radicals; Humans; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Precancerous Conditions; Uterine Cervical Neoplasms

The molar ratio between a diene-conjugated linoleic-acid isomer (18:2(9,11)) and the parent linoleic acid (18:2(9,12)), both esterified as phospholipids, was significantly different in exfoliated cells from normal cervices and from cervices with colposcopic and cytological evidence of precancer. The measurement may provide a simple and perhaps improved alternative to cytological screening.

Topics: Adult; Biopsy; Colposcopy; Female; Humans; Linoleic Acid; Linoleic Acids; Linoleic Acids, Conjugated; Precancerous Conditions; Uterine Cervical Neoplasms; Vaginal Smears