Polyunsaturated Fraction Research Articles

Bayesian analysis of cultivar and climate effects on seed and oil production in linseed

Linseed oil is utilised in a broad range of industrial and food applications, which make desirable a thorough understanding of the factors that influence its yield and quality. In this study, we used a Bayesian hierarchical model to investigate the impact of genotype and climatic variables on linseed seed and oil yield, as well as fatty acid composition, by utilising a germplasm collection database. Data were collected for 25 years at two nearby locations in Northern Italy, covering between 192 and 252 cultivars. After model optimisation, the cultivar-specific intercept coefficient exhibited the highest degree of differentiation across cultivars for all the variables under investigation. The response to temperature showed on the other hand no difference among cultivars, but it was generally negative for seed yield and seed oil content while it did not impact on fatty acids except for reducing the ratio of polyunsaturated to saturated fats in a few cultivars. A higher variability was detected for the cultivar response to rainfall, which affected seed yield and oil content either negatively or positively. Rainfall also influenced fatty acid composition, in particular the fraction of monounsaturated acids which were negatively impacted in all cultivars. Overall, the seed yield was the variable most affected by weather factors, which accounted for a value ranging between −27.9 % and 14.9 % on the average characteristic value of the cultivar, whereas for all other variables, the deviation was always less than 8 % in absolute value. The study also analysed the effect of autumn sowing compared to spring sowing, more commonly practiced in the study sites. Autumn sowing increased seed yield by up to 79.4 %, whereas oil content rose by no more than 1.6 %. While the saturated and monounsaturated fractions of fatty acids decreased, the polyunsaturated fraction rose to a maximum of 13.1 %. The ratio of polyunsaturated to saturated fats was increased up to 29.4 %.

Nutritional characterization of Trachurus lathami discarded by the Argentine fishing industry: first step towards the sustainable valorization of the species

In the Argentine Continental Shelf pelagic fisheries, rough scad (Trachurus lathami) is incidentally caught, being discarded by the commercial fleet despite its high abundances. With the aim of promoting the sustainable use of this species, the nutritional characterization of T. lathami is reported here for the first time. High protein (16%) and lipid (5.4%) content in whole individuals indicated that this is a moderately fat species. In the edible portion, within total lipids (4.8%), the n-3 polyunsaturated fraction was represented by docosahexaenoic (16.8%) and eicosapentaenoic (5.6%) acids. Results encourage potential strategies towards the developing of restructured products for human consumption.

Amino acid and fatty acid compositions of texturized vegetable proteins

Texturized proteins are the main ingredients of meat analogues. This paper evaluated the amino acid and the fatty acid compositions of texturized proteins produced by pea isolates, soy isolates, or dry-fractionated pea proteins, all combined with oat proteins. The nutritional composition was significantly affected by the protein sources. All the texturized proteins had a balanced amino acid profile, complying with the recommendations by FAO/WHO, except for the sulfur amino acids. The fatty acid profile showed the predominance of the polyunsaturated fraction, which was the highest in the dry-fractionated pea mixes. The trans-isomers’ content was lower than 0.5%.

Clinical effect, changes in the lipid structure of the erythrocyte membrane and microcirculation in patients with arterial hypertension in combination with coronary heart disease under the influence of laser therapy

To evaluate the clinical effect of LT in patients with hypertension in combination with coronary artery disease and trace its relationship with the dynamics of the structure of the lipid bilayer of the erythrocyte membrane and changes in the microvascular bed. We examined 65 male patients (mean age 50.9±6.3 years) with II-III degree AH in combination with coronary artery disease with angina pectoris. Among them, 40 patients received a 10-day course of LT, and 25 patients underwent simulated laser irradiation. At the initial stage and after 1 month, all patients underwent a bicycle exercise test, a study of the lipid composition of the erythrocyte membrane, including the main fractions of phospholipids and free cholesterol, as well as the level of intracellular Ca2+ and lipid peroxidation products - malondialdehyde and diene conjugates. Microcirculation was assessed using the method of conjunctival biomicroscopy. One month after the course of LT, patients showed a significant increase in exercise tolerance by 37.8%, a decrease in systolic blood pressure with a standard load by 9.9%. The improvement of the clinical picture occurred against the background of a decrease in the activity of lipid peroxidation and structural changes in the cell membrane: an increase in polyunsaturated fractions of phospholipids and a decrease in the cholesterol content, as well as a decrease in the Ca2+ level in the cell from 0.23 [0.19; 0.32] to 0.20 [0.16; 0.26] mmol/l. The results of the analysis of conjunctival biomicroscopy demonstrated a statistically significant decrease in the ratio of arteriolovenular calibers, a limitation of the severity of sludge syndrome by 59%, and an almost twofold (from 3.9±0.52 to 7.2±1.23 cap/mm2) increase in capillary density. The data obtained showed that in patients with hypertension in combination with coronary artery disease, LT causes positive changes in the lipid structure of the cell membrane and microcirculation parameters, which is accompanied by a hypotensive effect and an improvement in the clinical and functional state of patients.

Lipid Profile and Hepatic Fat Content Measured by 1H MR Spectroscopy in Patients before and after Liver Transplantation.

Increased hepatic fat content (HFC) is a hallmark of non-alcoholic fatty liver (NAFL) disease, a common condition in liver transplant recipients. Proton MR spectroscopy (1H MRS) and MR imaging-based proton density fat fraction as the only diagnosis modality enable precise non-invasive measurement of HFC and, also, fatty acid profiles in vivo. Using 1H MRS at 3T, we examined 47 liver transplantation candidates and 101 liver graft recipients. A point-resolved spectroscopy sequence was used to calculate the steatosis grade along with the saturated, unsaturated and polyunsaturated fractions of fatty acids in the liver. The steatosis grade measured by MRS was compared with the histological steatosis grade. HFC, represented by fat fraction values, is adept at distinguishing non-alcoholic steatohepatitis (NASH), NAFL and non-steatotic liver transplant patients. Relative hepatic lipid saturation increases while unsaturation decreases in response to increased HFC. Additionally, relative hepatic lipid saturation increases while unsaturation and polyunsaturation both decrease in liver recipients with histologically proven post-transplant NASH or NAFL compared to non-steatotic patients. HFC, measured by in vivo 1H MRS, correlated well with histological results. 1H MRS is a simple and fast method for in vivo analysis of HFC and its composition. It provides non-invasive support for NAFL and NASH diagnoses.

Simulating oilseed fatty acid composition through a stochastic modelling approach

A simulation model was developed to study the accumulation dynamics of seed oil fatty acids (FAs) in response to environmental stimuli. The Petri Net (PN) formalism was used to encode a virtual analogue of the FA biosynthetic pathway, where the process is governed by rules targeting enzymatic regulatory mechanisms. Four alternative types of rules were conceived: i) constant enzymatic activity throughout seed development; ii) enzymatic activity regulated by temperature; iii) enzymatic activity regulated by time-dependent gene expression; iv) combination of temperature- and time-dependent regulatory mechanisms. A set of 10 PN-based candidate models were built upon these rules to be evaluated against real oil composition data gathered during seed development.Camelina sativa (L.) Crantz was chosen as a case-study crop to test model performance. Published experimental datasets from Italy, Spain and the USA were used to calibrate and validate the models through a cross-validation procedure.Models incorporating endogenous time-based regulation showed higher predictive power than those built upon temperature-based rules, but the best results were obtained when combinations of both types of rules were used. The highest scoring model used the beta function to model endogenously regulated time-dependency of enzymatic activity, and the response to temperature. The fitted model correctly reproduced time-course FA accumulation. In order to assess its behaviour under climate change, sample simulations were run under two artificial scenarios, one characterized by increased air temperature, and the other by imposed restriction to photosynthetic carbon supply to the seed. The latter scenario was intended to mimic drought stress in particular. At higher temperatures the model predicted an increase in saturated and monounsaturated FAs, with a concomitant decrease of the polyunsaturated fraction.Under simulated carbon restrictions the prevailing behaviour was a lowering of monounsaturated FAs whereas the polyunsaturated fraction markedly increased. In both case-studies the predicted responses were found to be consistent with previous literature reports.

Black Soldier Fly (Hermetia Illucens) as Dietary Source for Laying Quails: Live Performance, and Egg Physico-Chemical Quality, Sensory Profile and Storage Stability.

Simple SummaryThe search for alternative and sustainable protein sources in poultry production is an issue of major importance due to the increasing demand of products of animal origin and, consequently, of feedstuffs to feed food-producing animals. The latter is exacerbating the overexploitation of natural resources, thus increasing the environmental impact of animal farming, as well as the prices of raw materials. In this sense, insects have been indicated as one of the possible alternatives to solve this problem, thus research efforts to test the feasibility of a practical application to the poultry sector are required. Therefore, the present study tested different inclusion levels of a defatted black soldier fly larvae protein meal in the diets for laying quails as an alternative ingredient to the soybean meal and oil. Results of the present study showed that the insect meal can technically be applied to laying quails’ feed formulations, providing optimal performance and health status. Egg nutritional quality and sensory profile too did not worsen when quails were fed with the insect meal supplementation. Further research efforts should be performed to improve the healthiness of the lipid fraction of the tested insect larvae and, in turn, the lipid quality of the eggs obtained from insect-fed quails. Insects are promising candidates as alternative sustainable sources of protein for poultry species. The present research studied the effect of a dietary inclusion of a defatted black soldier fly (BSF) larvae meal as an alternative protein source in the diets of laying quails, on productive performance, egg physicochemical quality, fatty acid profile, sensory traits and storage stability. A total of 225 laying quails were divided into 3 dietary groups (5 replicates/each). A conventional soybean meal-based diet was formulated (Control group), and two other diets were formulated including either 10% (BSF10) or 15% (BSF15) defatted BSF larvae meal. Laying quails showed satisfactory productive performance throughout the trial. BSF10 and BSF15 eggs had the highest shape index (p < 0.01), shell weight and percentage (p < 0.001) and the most intense yolk color (p < 0.001). Defatted BSF larvae meal increased the eggs’ saturated fatty acid content (p < 0.001) to the detriment of the polyunsaturated fraction (p < 0.001). Overall the eggs’ sensory profile was not affected by the dietary treatment, but BSF15 eggs had a higher feed off-flavor vs Control group (p < 0.05). At day 28 of storage, oxidative stability was higher in BSF10 vs. Control eggs (p < 0.01). Defatted BSF larvae meal can be considered a possible alternative ingredient to soybean meal in laying quail diets, up to the 15% inclusion level.

The role of thyroid hormones in regulating of fatty acid spectrum of brain lipids: ontogenetic aspect.

In experiments on rats of three age groups the role of thyroid hormones in the regulation of fatty acid spectrum of cortical and hippocampus lipids was studied. It was found that on the background of decreased thyroid status content of polyunsaturated fractions of free fatty acids, significantly changed depending on the age of the animals. In particular, in juvenile rats hypothyroidism was accompanied by a decrease almost twice the number of pentacodan acid decreased lipids viscosity in neurocortex. In old rats reduce of pentacodan acid in the cortex (38%) was supplemented by significant (77%) decrease in linoleic and linolenic acids. Unlike the two age groups deficiency of thyroid hormones in young animals caused accumulation of free polyunsatarated fatty acids (C18: 2.3) in the cerebral cortex by 74%, which may be associated with a decrease of this fraction in fatty acid spectrum of lipids and increase of viscosity properties of the membranes. These restruc­turing may be associated with modulation of synaptic transmission of specific neurotransmitter systems in the brain.

Phospholipase C and Protein Kinase C-β 2 Mediate Insulin-Like Growth Factor II-Dependent Sphingosine Kinase 1 Activation

We recently reported that IGF-II binding to the IGF-II/mannose-6-phosphate (M6P) receptor activates the ERK1/2 cascade by triggering sphingosine kinase 1 (SK1)-dependent transactivation of G protein-coupled sphingosine 1-phosphate (S1P) receptors. Here, we investigated the mechanism of IGF-II/M6P receptor-dependent sphingosine kinase 1 (SK1) activation in human embryonic kidney 293 cells. Pretreating cells with protein kinase C (PKC) inhibitor, bisindolylmaleimide-I, abolished IGF-II-stimulated translocation of green fluorescent protein (GFP)-tagged SK1 to the plasma membrane and activation of endogenous SK1, implicating PKC as an upstream regulator of SK1. Using confocal microscopy to examine membrane translocation of GFP-tagged PKCα, β1, β2, δ, and ζ, we found that IGF-II induced rapid, transient, and isoform-specific translocation of GFP-PKCβ2 to the plasma membrane. Immunoblotting of endogenous PKC phosphorylation confirmed PKCβ2 activation in response to IGF-II. Similarly, IGF-II stimulation caused persistent membrane translocation of the kinase-deficient GFP-PKCβ2 (K371R) mutant, which does not dissociate from the membrane after translocation. IGF-II stimulation increased diacylglycerol (DAG) levels, the established activator of classical PKC. Interestingly, the polyunsaturated fraction of DAG was increased, indicating involvement of phosphatidyl inositol/phospholipase C (PLC). Pretreating cells with the PLC inhibitor, U73122, attenuated IGF-II-dependent DAG production and PKCβ2 phosphorylation, blocked membrane translocation of the kinase-deficient GFP-PKCβ2 (K371R) mutant, and reduced sphingosine 1-phosphate production, suggesting that PLC/PKCβ2 are upstream regulators of SK1 in the pathway. Taken together, these data provide evidence that activation of PLC and PKCβ2 by the IGF-II/M6P receptor are required for the activation of SK1.

In vivo determination of human breast fat composition by 1H magnetic resonance spectroscopy at 7 T

The role of diet and fat consumption in the pathogenesis of breast cancer is an important subject. We report a method for noninvasive determination of lipid composition in human breast by proton magnetic resonance spectroscopy (MRS) at 7 T. Two respiratory-triggered TE-averaged stimulated echo acquisition mode (STEAM) acquisitions were performed on the adipose tissue of 10 healthy volunteers where the second acquisition had all gradients inverted. This acquisition protocol allows the suppression of modulation sidebands that complicate spectral analysis at the short TE(avg) = 24.5 ms. The entire acquisition takes ∼10 min. Ten lipid peaks were typically resolved. T(1) and T(2) were also measured and used to correct the peak intensities. The calculated average lipid composition for saturated was 28.7 ± 8.4%, monounsaturated, 48.5 ± 7.9%, and polyunsaturated, 22.7 ± 3.1%, in close agreement with reported values from subcutaneous adipose measurements. Intrasubject variability was 2.0, 1.6, and 3.6% for the saturated, monounsaturated, and polyunsaturated fractions, respectively. In conclusion, we have shown that a chemical analysis of lipids in breast tissue can be determined quite simply, quickly, and noninvasively by proton MRS at 7 T.

The Lipid Quality Assessment of Schizothorax zarudnyi and Schizocypris altidorsalis by Fatty Acid Analysis

The proximate and fatty acid composition of two locally important freshwater fish, Schizothorax zarudnyi and Schizocypris altidorsalis, from Sistan Province in Iran were investigated for their nutritional value. The protein and lipid content in the S. zarudnyi were 14.67 and 6.36%, respectively. In S. altidorsalis, protein and lipid content were 13.03 and 4.52%. There was quantitative difference between individual fatty acids of these two fish. Totally 18 fatty acids were found. In S. zarudnyi, DHA was the highest among the poly-unsaturated fatty acids with 42.85%, followed by EPA with 29.62% of the total poly-unsaturated fraction. In S. altidorsalis, EPA was the highest among the poly-unsaturated fatty acids with 45.05%, followed by DHA with 27.87% the total poly-unsaturated fraction. The n-6/n-3 ratio was 0.26 and 0.20 for S. zarudnyi and S. altidorsalis, respectively. High n-3 fatty acids content in these fish revealed that they have high nutritional value. Schizothorax zarudnyi showed better nutritional value in comparison to protein and lipid content of S. altidorsalis.

DSC analysis of human fat tissue in steroid induced osteonecrosis

Osteonecrosis (ON) of the femoral frequently occurs after steroid medication. One of the final pathways leading to steroid induced ON is thought to be pathologic fat metabolism. The pathobiological mechanism underlying the induction of fat metabolism outslides by steroids leading to ON has not been fully elucidated. The purpose of this study was to examine the intraoperative obtained gluteal fat tissue from ON patients with histology, gas chromatography (GC) and differential scanning calorimetry (DSC) and to compare them with otherwise healthy patient’s samples. The histological sections showed no significant differences compared with the control group. GC revealed that fraction of saturated fatty acids decreased in ON samples from mean values of controls of 24% to 21, the polyunsaturated fraction from 20 to 14%. The monounsaturated acids showed an increase from mean rate of 52% of the controls to 65% of steroid treated samples. DSC curves correlate with chromatographic analysis of the tissue fatty acids (Steroid treated, heating between 0–100°C: Tm=5.7°C, ΔH= −15.8J/g−1; heating between −20–100°C: Tm= −9.96 and 5.85°C, ΔH= −59.17 and −16.2 J g−1. Non-necrotic, heating between 0–100°C: two separable transition with Tm=5.7 and 9.9°C, total ΔH= −20.8 J g−1; heating between −20–100°C: Tm= −10.9 and 4.95°C, total ΔH= −75.8 J g−1.)

Effects of oilseed supplements on milk production and quality in dairy cows fed a hay-based diet

The influence of rapeseed (Brassica napus L.) and linseed (Linum usitatissimum L.) on feed consumption, milk yield, composition and fatty acid (FA) profile was investigated in lactating dairy cows. According to a Latin square design, twelve cows were assigned to three experimental settings which received a hay-based diet supplemented with one of the following mixtures: cracked barley (1.0 kg) and cracked maize (0.5 kg) as Control diet (C-diet); full fat ground rapeseed (1.0 kg), cracked barley (1.0 kg) and cracked maize (0.5 kg) as Rapeseed diet (R-diet) and extruded linseed (1.2 kg), cracked barley (1.0 kg) and cracked maize (0.5 kg) as Linseed diet (L-diet). Diet supplemented with rape- and linseed did not affect dry matter intake. As result of the high amount of dietary ether extract R- and L-diet showed higher crude fat intake as compared to the control. Despite the higher intake of crude fat and, in particular, of the polyunsaturated fraction, milk yield and composition resulted similar among treatments. Compared to C-diet, R-diet resulted in milk containing significantly lower amounts of saturated fatty acids (SFA) (60.9 vs 66.9% of total detected SFA) as well as higher amounts of monounsaturated fatty acids (MUFA) (30.6 vs 24.2%). However, R-diet had no effect on polyunsaturated fatty acid content (PUFA). With respect to C-diet, L-diet also significantly reduced the content of SFA (59.8 vs 66.9%) and increased both MUFA (29.1 vs 24.2%) and PUFA (4.7 vs 4.1%) contents. Feeding about 1 kg of whole oilseeds per head per day had no clear effects on milk vaccenic acid and conjugated linoleic acid contents. The inclusion of rapeseed in the diet significantly reduced the content of n-6 FA in the milk, whereas the linseed-supplemented diet significantly increased the content of n-3 FA. In comparison to C-diet, n-6/n-3 ratio was lower in L-diet milk and intermediate in R-diet milk. Feeding lactating dairy cows with oilseeds rich in unsaturated fatty acids (UFA) did not exert any effects on productive performance. Considering the increase in PUFA and the reduction of n-6/n-3 ratio as a desirable enrichment of milk fat for human health, under our experimental condition feeding linseed appears to improve the nutritional value of milk better than rapeseed.

Effect of dietary conjugated linoleic acid on muscle, liver and visceral lipid deposition in rainbow trout juveniles ( Oncorhynchus mykiss)

Some of the conjugated linoleic acids (CLA), cis-9, trans-11 and trans-10, cis-12 isomers, may present a wide range of health benefits. Taking into account these beneficial effects and the relative low amounts of CLA in fish products, commercial diets for juvenile rainbow trout were supplemented with graded levels (0, 0.5, 0.75, 1 and 2%) of CLA. Duplicated groups of 5.3 g fish were fed to satiation, twice a day, over a period of 12 weeks with a CLA mixture, containing mainly the bioactive cis-9, trans-11 and trans-10, cis-12 isomers. The increase of dietary CLA levels did not affect growth performance, feed conversion ratio (FCR), hepatosomatic index (HSI) or viscerosomatic index (VSI) of the rainbow trout juveniles. Total lipids in muscle and liver were similar among treatments. In viscera, CLA supplementation reduced total lipids, but only the 0.5% CLA treatment differed significantly from the control. The fatty acid profile was affected by the dietary inclusion of CLA, resulting in a significant increase of the saturated and polyunsaturated fractions and a general decrease of the monounsaturated one, in both muscle and viscera. Nevertheless, in liver only fish fed 1% CLA had a significantly higher saturated fraction. The general decreases of monounsaturated fatty acid level in tissues with the saturated increase suggest a reduction of Δ-9 desaturase activity. CLA was deposited in all tissues and reflected the dietary CLA level. The highest concentration was attained when the 2% diet was used (6.9 g/100 g lipids in muscle). In conclusion, rainbow trout are capable of incorporating CLA in muscle, liver and viscera better than any other vertebrate, showing that this species is a potential route to increase human CLA ingestion.

Nutritional quality of red shrimp, Aristeus antennatus (Risso), pink shrimp, Parapenaeus longirostris (Lucas), and Norway lobster, Nephrops norvegicus (Linnaeus)

AbstractThe proximate composition, amino acid and fatty acid profiles, lipid classes and cholesterol and glycogen contents were determined in the edible part of red shrimp, Aristeus antennatus (Risso), pink shrimp, Parapenaeus longirostris (Lucas), and Norway lobster, Nephrops norvegicus (Linnaeus), in two distinct periods of the year. The proximate composition did not vary significantly between species or between periods of sampling. Significant differences in glycogen content were obtained between winter and summer; the lowest values were attained in winter (1.2, 1.1 and 1.0% wet weight for red shrimp, pink shrimp and Norway lobster respectively). With the exception of Norway lobster, an opposite trend was obtained for cholesterol content, ie lower values in summer (60.8 and 57.8 mg per 100 g wet weight for red shrimp and pink shrimp respectively). The major essential amino acids (EAA) were arginine, lysine and leucine and the limiting amino acid was methionine in all three crustacean species. The most important non‐essential amino acids (NEAA) were glutamic acid, aspartic acid, proline and glycine. In respect to lipid classes, phospholipids and free cholesterol predominated. The major fatty acids were 16:0, 18:1n‐9, 20:5n‐3 and 22:6n‐3. The polyunsaturated fraction was dominant (42.1–48.4%), followed by the monounsaturated (26.3–34.6%) and saturated (22.9–27.4%) fatty acids. In conclusion, the nutritional quality of these shellfish species is similar, they are valuable protein and lipid sources for the human diet and are adequate elements of the traditional Portuguese diet. Copyright © 2003 Society of Chemical Industry

Growth and fatty acid composition of freshwater prawn, Macrobrachium rosenbergii, larvae fed diets containing various ratios of cod liver oil-corn oil mixture

Summary A feeding trial was conducted to determine the effect of replacing costly cod liver oil with corn oil as a source of dietary lipid on the growth and fatty acid composition of the larval freshwater prawn, Macrobrachium rosenbergii de Man. Prawn larvae were weaned to artificial diets containing cod liver oil and corn oil either singly or in various combinations (2 : 1, 1 : 1, 1 : 2, w/w). Weaning to artificial diets from Artemia nauplii commenced at larval stage III with complete substitution by stage X. The reference group was reared solely on Artemia nauplii during the entire experiment. Incorporation of corn oil at 33–67% of dietary supplemental oil did not have significant effects on the post-larval production. However, larvae fed with corn oil alone revealed a significantly lower post-larval production compared to other experimental diets as well as to the reference group. No significant differences (P > 0.05) were observed in dry weight, protein and lipid concentration among larvae fed on various dietary treatments. Palmitic (16 : 0) and oleic/vaccenic (18 : 1) acids were the dominant saturated and monounsaturated fatty acids in larval tissues, respectively, whereas the polyunsaturated fraction was dominated by eicosapentaenoic (20 : 5n-3) acid. The polyunsaturated fatty acid composition was dominated by n-3 acids rather than n-6 fatty acids. The fatty acid composition of the prawn in general reflected that of the diet. Larvae on diets containing higher concentrations of corn oil rich in linoleic (18 : 2n-6) acid showed a higher concentration of this acid in their tissues. No evidence of de novo synthesis of linoleic (18 : 2n-6) acid was found. Higher levels of stearic (18 : 0), arachidonic (20 : 4n-6) and eicosapentaenoic (20 : 5n-3) acids found in larvae as compared with those fed Artemia and artificial diets strongly indicated the larval ability in chain elongation and desaturation of palmitic (16 : 0), linoleic (18 : 2n-6) or linolenic (18 : 3n-3) acids, respectively. Despite a large variation of n-3 to n-6 ratios of the live and artificial diets, larval n-3 to n-6 ratios were relatively stable among different dietary treatments, possibly indicative of the importance of such a ratio in the larval fatty acid metabolism.

Vitamin E, lipid profile, and peroxidation in hemodialysis patients

Hypertriglyceridemia, lipid peroxidation, and abnormalities of the plasma fatty acid (PUFA) profile may be important risk factors for the atherosclerotic cardiovascular disease in hemodialysis (HD) patients. We investigated how these factors are affected by vitamin E supplementation carried out by oral administration (clinical study 1) and dialysis with vitamin E-modified dialyzers (clinical study 2). In the HD patients, conditions of relative vitamin E deficiency were observed [lowered vitamin E/triglyceride (TG) ratio] in the presence of high levels of thiobarbituric acid reactants (TBARs) and decreased levels of the polyunsaturated fraction of PUFAs paired with an increased amount of monounsaturated ones (MUFA). In both studies, vitamin E supplementation significantly increased the levels of vitamin E in the plasma without affecting TG levels and provided a partial correction of TBAR levels. Of note was the relative increase in the PUFA fraction, which gave solid proof of an anti(per)oxidant effect of vitamin E supplementation in HD patients. Vitamin E supplementation was also observed to increase plasma levels of reduced glutathione and NOx (NO2 + NO3). The results suggest that vitamin E supplementation may be an effective accessory therapy to combat oxidative stress-lowering lipid peroxidation in HD patients.

Separation of molecular species of triacylglycerols by high-performance liquid chromatography with a silver ion column

Molecular species representative of the wide range of triacylglycerols occurring in nature, ranging from relatively saturated fats such as that from sheep adipose tissue through polyunsaturated seed oils, including sunflower and linseed oils, to an oligounsaturated fish oil, have been resolved by high-performance liquid chromatography in the silver ion mode. The stationary phase consisted of an ion-exchange medium, which was a silica gel matrix with bonded sulphonic acid moieties, loaded with silver ions. The mobile phase for the more saturated fractions was a gradient of acetone into 1,2-dichloroethane-dichloromethane, then acetonitrile was introduced to elute polyunsaturated fractions. A mass detector was employed to monitor separations. Fractions were collected via a stream-splitter for identification and quantification by gas chromatography as methyl esters. Excellent resolution was obtained on the silver ion column with no contamination of fractions with silver ions, while the column was stable and retained its activity in prolonged use.

A novel group of very long chain polyenoic fatty acids in dipolyunsaturated phosphatidylcholines from vertebrate retina.

Dipolyunsaturated phosphatidylcholines from bovine retina contain a whole series of unusual fatty acids. Methyl esters from these acids are very strongly retained on polar and nonpolar gas-liquid chromatography stationary phases. On thin layers of silica-AgNO3, they separate as tetra-, penta-, and hexaenoic fatty acid methyl esters. After hydrogenation, the three polyunsaturated fractions give the same series of saturated methyl esters, having 20 (or 22)-36 carbon atoms. High pressure liquid chromatography, as well as gas-liquid chromatography, indicates that the new components of the three fractions are even-carbon homologs of well known polyenoic fatty acids of the n-6 and n-3 families, since they behave as series of 20-36-carbon tetraenoic (n-6), pentaenoic (n-3 and n-6), and hexaenoic (n-3) fatty acids. Their occurrence in phospholipid molecules also having docosahexaenoate (22:6) explains the separation of major dipolyunsaturated phosphatidylcholines from retina into dodecaenoic, undecaenoic, and decaenoic fractions after argentation thin layer chromatography. Using high pressure liquid chromatography, the latter are resolved into individual species having 10-12 double bonds and 42-58 carbon atoms. The unusual PCs are thus endowed not only with the highest degree of unsaturation, but with the longest hydrocarbon chains yet reported for vertebrate glycerophospholipids. It is shown that phosphatidylcholines containing the novel fatty acids are highly concentrated in photoreceptor membranes and that they occur in the retina of vertebrates so distant in evolution as fish, birds, and various mammals.