Nutritional and medical importance of gamma-linolenic acid

Lack of effect of supplementation with essential fatty acids on bone mineral density in healthy pre- and postmenopausal women: two randomized controlled trials of Efacal v. calcium alone

Randomized controlled trials of the effects of the dietary supplement Efacal (Scotia Pharmaceuticals Plc, Guildford, Surrey, UK) v. Ca only on total body bone mineral density (BMD) and markers of bone turnover were conducted in healthy pre- and postmenopausal women separately. Total daily dose for 12 months for the Efacal groups was: Ca 1.0 g, evening primrose oil 4.0 g and marine fish oil 440 mg; and for the control groups was: Ca 1.0 g. Reported compliance was better than 90% in both age groups. For the forty-three premenopausal women (age range 25-40 years), initial mean total body BMD values were similar for Efacal and control groups and both groups showed highly significant mean increases of about 1%; however, there were no significant between-group differences for the changes in BMD or markers of bone turnover. For the forty-two postmenopausal women (age range 50-65 years), initial mean total body BMD values were again well-matched across treatment groups. Both Efacal and control groups showed highly significant decreases in total body BMD of about 1%, but again there were no significant between-group differences in total body BMD or markers of bone turnover. Possible confounding variables such as initial total body BMD were explored but had no effect on the outcome in either age group. Nail quality improved in both age groups and in both Efacal and control groups. Again, there was no significant difference between treatment groups. No evidence was found to support a beneficial effect of Efacal on BMD in these women.

Effects of early nutrition on free radical formation in VLBW infants with respiratory distress

OBJECTIVE

We studied the development of essential fatty acid deficiency (EFAD) and its effects together with those of vitamin E deficiency on the free radical formation of very low birth weight (VLBW) infants with respiratory distress.

METHODS

Infants were divided into three groups based on the way each was supplied with daily total energy intake: (1) by fat free parenteral nutrition only or by nutrition composed of (2) less than or (3) higher than 25% of total daily energy intake given in oral feeding. We measured plasma lipid parameters and autoxidative susceptibility (AOS) of red blood cells (RBCs).

RESULTS

Plasma concentrations of linoleic acid were low in all the groups. After at least 14 days of feeding, eicosatrienoic acid (EA) was not detected. One week after the introduction of oral feeding, the abnormal triene/tetraene ratio of the groups had decreased, but was not normalized. Vitamin E deficiency was associated with significantly increased AOS, but EFAD was not. The two factors together caused an increase of AOS, that was additive.

CONCLUSIONS

Our data confirm that EFAD increases AOS of RBCs in VLBW infants. We assume that prevention of EFAD in VLBW infants could decrease the prevalence of complications associated with free radical formation.

Occurrence and characterization of oils rich in gamma-linolenic acid Part I: Echium seeds from Macaronesia

Nineteen species of the genus Echium (Fam. Boraginaceae) collected in Macaronesia were surveyed in a search for new sources of gamma-linolenic acid (GLA, 18:3omega6). High amounts of this acid were found in all of them, ranging from 9.15% (E. plantagineum) to 26.31% (E. callithyrsum) of total seed fatty acids. The amounts of GLA related to total seed weight were also significant, ranging from 1.77% (E. sventenii) to 5.02% (E. nervosum). In addition, considerable amounts of stearidonic acid (SA, 18:4omega3) were detected, ranging from 3.03% (E. auberianum) to 12.94% (E. plantagineum) of total fatty acids. These data allow us to consider tile members of the genus Echium from Macaronesia as one of the richest sources of gamma-linolenic acid found so far in nature. The results obtained from multivariable data analysis and the taxonomic relationships among the species is discussed.

Gamma-linolenic acid provides additional protection against ventricular fibrillation in aged rats fed linoleic acid rich diets

Ligation of the coronary artery in rats produces severe ventricular fibrillation (VF) and malignant cardiac arrhythmia. Mortality increases with the age of the animal. Diets rich in saturated fatty acids (SF) but low in linoleic acid (LA) increase, but diets high in LA and low in SF decrease the severity of VF and mortality in older animals. The effects of an LA enriched diet can be blocked by inhibition of cyclooxygenase suggesting that conversion of LA to eicosanoids is central to the development of VF. Conversion of LA to gamma-linolenic acid (GLA) via delta-6 desaturase is the first step in the process. The activity of delta-6 desaturase declines with age. Thus inclusion of GLA in the diet of older animals may provide an additional benefit over LA alone. Dietary supplements of evening primrose oil (EPO) to one year old rats reduced ischaemic VF more than a supplement of sunflower seed oil (SSO) without GLA. Substitution of borage oil (more GLA than EPO but less LA than either EPO or SSO) was without additional benefit.

Regulation of fatty acid biosynthesis as a possible mechanism for the mitoinhibitory effect of fumonisin B1 in primary rat hepatocytes

The mitoinhibitory effect of fumonisin B1 (FB1) on the mitogenic response of epidermal growth factor (EGF) was investigated in primary hepatocyte cultures with respect to the alterations in the omega6 fatty acid metabolic pathway. Fatty acid analyses of hepatocytes showed that EGF treatment resulted in a significant decrease in the relative levels of 20:4omega6 (arachidonic acid) and an increase in 18:2omega6 (linoleic acid). Supplementation of the hepatocyte cultures with 20:4omega6 in the absence of EGF resulted in an increase in the total omega6 and omega6/omega3 fatty acid ratio. Addition of 20:5omega3 (eicosapentaenoic acid) resulted in an increase of the relative levels of the long chain omega3 fatty acids at the expense of the omega6 fatty acids. When 20:4omega6 and 20:5omega3 was added in the presence of EGF, the mitogenic response of EGF was increased and decreased respectively. When compared to the fatty acid profiles in the absence of EGF, the decreased mitogenic response coincided with a decrease of total omega6 fatty acids and total polyunsaturated fatty acids (PUFA). In addition, the saturated and mono-unsaturated fatty acids increased and the polyunsaturated/saturated (P/S) fatty acid ratio decreased which implied a more rigid membrane structure. Addition of prostaglandin E2 (PGE2) and prostaglandin E1 (PGE1) stimulated and inhibited the mitogenic response respectively. Ibuprofen, a known cyclooxygenase inhibitor, and FB1 inhibited the EGF-induced mitogenic response in a dose-dependent manner. The mitoinhibitory effect of FB1 on the EGF response was counteracted by the addition of PGE2. FB1 also disrupts the omega6 fatty acid metabolic pathway in primary hepatocytes, resulting in the accumulation of C18:2omega6 in phospatidylcholine and triacylglicerol. The disruption of the omega6 fatty acid metabolic pathway and/or prostaglandin synthesis is likely to be an important event in the mitoinhibitory effect of FB1 on growth factor responses.

Delta6-fatty acid desaturase from an arachidonic acid-producing Mortierella fungus. Gene cloning and its heterologous expression in a fungus, Aspergillus

A DNA fragment was cloned from the fungal strain, Mortierella alpina 1S-4 (which is used industrially to produce arachidonic acid), after PCR amplification with oligonucleotide primers designed based on the sequence information for delta6-desaturase genes (from borage and Caenorhabditis elegans), which are involved in the desaturation of linoleic acid (delta9, delta12-18:2) to gamma-linolenic acid (delta6, delta9, delta12-18:3). This fragment was used as a probe to isolate a cDNA clone with an open reading frame encoding 457 amino acids from a M. calpina 1S-4 library. The predicted amino-acid sequence showed similarity to those of the above delta6-desaturases, and contained a cytochrome b5-like domain at the N-terminus, being different from the yeast delta9-desaturase which has the corresponding domain at the C-terminus. The full-length cDNA clone was expressed under the control of the amyB promoter in a filamentous fungus, Aspergillus oryzae, resulting in the accumulation of gamma-linolenic acid (which was not detected in the control Aspergillus) to the level of 25.2% of the total fatty acids. These findings revealed that the recombinant product has delta6-desaturase activity. The Mortierella delta6-desaturase is the first to be reported in fungi.

Cloning of delta12- and delta6-desaturases from Mortierella alpina and recombinant production of gamma-linolenic acid in Saccharomyces cerevisiae

Two cDNA clones with homology to known desaturase genes were isolated from the fungus Mortierella alpina. The open reading frame in one clone encoded 399 amino acids and exhibited delta12-desaturase activity when expressed in Saccharomyces cerevisiae in the presence of endogenous fatty acid substrate oleic acid. The insert in another clone contained an open reading frame encoding 457 amino acids and exhibited delta6-desaturase activity in S. cerevisiae in the presence of exogenous fatty acid substrate linoleic acid. Expression of the delta12-desaturase gene under appropriate media and temperature conditions led to the production of linoleic acid at levels up to 25% of the total fatty acids in yeast. When linoleic acid was provided as an exogenous substrate to the yeast cultures expressing the delta6-desaturase activity, the level of gamma-linolenic acid reached 10% of the total yeast fatty acids. Co-expression of both the delta6- and delta12-desaturase cDNA resulted in the endogenous production of gamma-linolenic acid. The yields of gamma-linolenic acid reached as high as 8% of total fatty acids in yeast.

Uptake of 13C-tracer arachidonate and gamma-linolenate by the brain and liver of the suckling rat observed using 13C-NMR

Arachidonic acid (AA; 20:4n-6) is one of the principal components of the phosphoglycerides in neural cell membranes. During the critical period of postnatal development in mammals, AA is supplied preformed, directly from the milk or derived from precursor fatty acids such as gamma-linolenic acid (GLA; 18:3n-6). In this study, 13C-NMR spectroscopy was applied to investigate the incorporation of [1-(13)C]AA and [3-(13)C]GLA into liver and brain lipids of 7-15-day-old rats. The main objective was to establish the importance of dietary GLA for tissue AA accretion relative to the contribution from preformed dietary AA. [1-(13)C]AA and [3-(13)C]GLA were injected into the stomach of 7-day-old rats as a mixture. 13C-NMR spectroscopy of lipid extracts revealed incorporation of [1-(13)C]AA and [5-(13)C]AA (the latter derived from metabolism of the injected [3-(13)C]GLA) into phosphoglycerides and triacylglycerols. Preformed AA was 10 (liver)-17 (brain) times more efficient in contributing to tissue AA than AA derived from precursor GLA. In separate experiments, NMR spectroscopy was used to assess uptake of [1-(13)C]AA directly in living rats and intact organs. Results showed that intact liver and brain contain an appreciable amount of NMR-detectable lipids. The in vivo/in vitro information obtained from organs provided details on the mobility and turnover of tissue lipids.

Identification of Delta12-fatty acid desaturase from arachidonic acid-producing mortierella fungus by heterologous expression in the yeast Saccharomyces cerevisiae and the fungus Aspergillus oryzae

Based on the sequence information for the omega3-desaturase genes (from Brassica napus and Caenorhabditis elegans), which are involved in the desaturation of linoleic acid (Delta9, Delta12-18 : 2) to alpha-linolenic acid (Delta9, Delta12, Delta15-18 : 3), a cDNA was cloned from the filamentous fungal strain, Mortierella alpina 1S-4, which is used industrially to produce arachidonic acid. Homology analysis with protein databases revealed that the amino acid sequence showed 43.7% identity as the highest match with the microsomal omega6-desaturase (from Glycine max, soybean), whereas it exhibited 38.9% identity with the microsomal omega3-desaturase (from soybean). The evolutionary implications of these enzymes will be discussed. The cloned cDNA was confirmed to encode a Delta12-desaturase, which was involved in the desaturation of oleic acid (Delta9-18 : 1) to linoleic acid, by its expression in both the yeast Saccharomyces cerevisiae and the fungus Aspergillus oryzae. Analysis of the fatty acid composition of yeast and fungus transformants demonstrated that linoleic acid (which was not contained in the control strain of S. cerevisiae) was accumulated in the yeast transformant and that the fungal transformant contained a large amount of linoleic acid (71.9%). Genomic Southern blot analysis of the transformants with the Mortierella Delta12-desaturase gene as a probe confirmed integration of this gene into the genome of A. oryzae. The M. alpina 1S-4 Delta12-desaturase is the first example of a cloned nonplant Delta12-desaturase.

Occurrence of gamma-linolenic acid in compositae: a study of Youngia tenuicaulis seed oil

Seeds of Youngia tenuicaulis and other species from the plant family Compositae (Asteraceae) were studied for their oil content and fatty acid composition. The seed oil of Y. tenuicaulis growing in Mongolia was found to contain 5.6% gamma-linolenic acid (18:3delta6cis,9cis,12cis) in addition to common fatty acids. The oil was analyzed using chromatographic [capillary gas-liquid chromatography (GLC), thin-layer chromatography] and spectroscopic (infrared, gas chromatography-mass spectrometry) techniques. Seed oil fatty acids of Saussurea amara (containing gamma-linolenic acid) and of Arctium minus (containing 18:3delta3trans,9cis,12cis), as well as delta5cis- and delta5trans-18:3 were used as GLC reference substances. The evolution in this plant family of a large number of different 18:3 acids as well as the corresponding evolution of unusual desaturases should be investigated. On the other hand, the delta6cis-desaturase required for the biosynthesis of gamma-linolenic acid may have evolved independently several times in unrelated families of the plant kingdom.

Differential effects of dietary Oenothera, Zizyphus mistol, and corn oils, and essential fatty acid deficiency on the progression of a murine mammary gland adenocarcinoma

The modulating effect of dietary enrichment in mistol seed oil (MO) containing 25% of alpha-linolenic acid (ALA), evening primrose oil (EPO) enriched in gamma-linolenic acid (GLA) and corn oil (CO) as sources of omega-6 and omega-9 fatty acids on the growth parameters of one transplantable mammary tumor were compared. Mice fed on different lipid formulae were inoculated with a mammary gland adenocarcinoma and different growth development tumor parameters were recorded. Results showed that corn oil feeding slowed down most of the tumor growth parameters, as did the EPO diet. MO also showed antitumor activity. Olein feeding, which induces an essential fatty acid deficiency (EFAD), increased the incidence and the multiplicity of metastases when compared with the controls. It may be concluded that a diet enriched in omega-6 fatty acids did not behave as a tumor promoter in this mammary gland tumor model. The antitumor activities of EPO and MO are corroborated in present experiments, suggesting that both oils may be of value in nutritional approaches of mammary gland tumor therapies. In addition, present data add further experimental proof about the proposed protumorigenic proneness induced by the EFAD state.

New gene targets related to schizophrenia and other psychiatric disorders: enzymes, binding proteins and transport proteins involved in phospholipid and fatty acid metabolism

Phospholipids make up about 60% of the brain's dry weight. In spite of this, phospholipid metabolism has received relatively little attention from those seeking genetic factors involved in psychiatric and neurological disorders. However, there is now increasing evidence from many quarters that abnormal phospholipid and related fatty acid metabolism may contribute to illnesses such as schizophrenia, bipolar disorder, depression and attention deficit hyperactivity disorder. To date the possible specific proteins and genes involved have been relatively ill-defined. This paper reviews the main pathways of phospholipid metabolism, emphasizing the roles of phospholipases of the A2 and C series in signal transduction processes. It identifies some likely protein candidates for involvement in psychiatric and neurological disorders. It also reviews the chromosomal locations of regions likely to be involved in these disorders, and relates these to the known locations of genes directly or indirectly involved in phospholipid and fatty acid metabolism.

Molecular cloning and functional characterization of rat delta-6 fatty acid desaturase

Mammalian cDNA fragments putatively encoding amino acid sequences characteristic of the fatty acid desaturase were obtained using expressed sequence tag (EST) sequence informations. These fragments were subsequently used to screen a rat liver cDNA library, yielding a 1573-bp clone. Expression of DNA fragment containing either of two possible open reading frames (nucleotide numbers 97-1431 and 148-1431) of the isolated clone in yeast led to the accumulation of gamma-linolenic acid in the presence of exogenous linoleic acid. In this system, the addition of alpha-linolenic acid also resulted in the accumulation of its Delta-6 desaturated product whereas dihomo-gamma-linolenic acid failed to be a substrate. These results indicate that the protein encoded by the rat cDNA is Delta-6 fatty acid desaturase, and the first 17 amino acids corresponding to the coding region 97-147 of the clone are not required to function in yeast.

Effects of dietary alpha- or gamma-linolenic acid on levels and fatty acid compositions of serum and hepatic lipids, and activity and mRNA abundance of 3-hydroxy-3-methylglutaryl CoA reductase in rats

The effects of diets containing equal amounts of alpha (alpha)- or gamma (gamma)-linolenic acid on lipid metabolism were compared in rats. Four groups of male Wistar rats were given the diets containing 20% perilla/corn mixed oil or borage oil in the absence (PO- and BO-diets, respectively) or presence (CPO- and CBO-diets) of cholesterol for 20 days. The PO-diet yielded lower serum cholesterol than the BO-diet, although the difference was not observed between the CPO and CBO groups. The PO and CPO groups showed lower high-density lipoprotein cholesterol than the BO and CBO groups, respectively. A similar tendency was observed in serum phospholipids. The CPO-diet gave markedly lower hepatic triglycerides than the CBO-diet. The activity of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was much lower on the PO-diet than on the BO-diet. mRNA abundance of HMG-CoA reductase was lower in rats on the PO-diet than on the BO-diet, though there was no significant difference between the CPO and CBO groups. The present results indicate that alpha-linolenic acid exhibits a larger hypocholesterolemic effect than gamma-linolenic acid, and it may be displayed mainly through the repression of the activity and mRNA expression of HMG-CoA reductase.

Randomized controlled trial of gamma-linolenic acid and eicosapentaenoic acid in peripheral arterial disease

BACKGROUND AND AIMS

epidemiological studies suggest polyunsaturated fatty acids protect against the development of atherosclerosis. The aim of this study was to perform a randomized controlled trial of gamma-linolenic and eicosapentaenoic acids in patients with lower limb atherosclerosis. Main outcome measures were: cholesterol and lipoprotein concentrations; haemostatic and rheological variables; the ankle brachial pressure index; walking distance; and cardiovascular events and death.

METHODS

120 men and women with stable intermittent claudication were randomized to 2 years treatment with either a combination of gamma-linolenic and eicosapentaenoic acids, or placebo.

RESULTS

39 (65.0 cent) of those taking fatty acids and 36 (60.0 cent) of those taking placebo completed the trial. Lipid concentrations did not differ significantly during the trial. In those taking fatty acids, haematocrit was significantly higher than in the placebo group after 6 months (46.1 cent compared with 44.6 cent, P </= 0.01), and systolic blood pressure was significantly lower after 2 years (150|mmHg compared with 161.8|mmHg, </= 0.05). There was no difference in walking distance, but there was a small reduction in non-fatal coronary events in the fatty acid group (10 cent compared with 15 cent, P > 0.05).

CONCLUSIONS

a combination of polyunsaturated fatty acids produced a statistically significant reduction in systolic blood pressure, but no other significant benefits on risk factors. The trend towards fewer coronary events in those taking fatty acids warrants further investigation.

Eicosatrienoic acid (20:3 n-9) inhibits the expression of E-cadherin and desmoglein in human squamous cell carcinoma in vitro

Eicosatrienoic acid (ETA 5,8,11, n-9) is abnormally increased by essential fatty acid deficiency (EFAD), a condition associated with alterations of cell proliferation and differentiation. In comparison to certain EFAs, addition of ETA at a low concentration resulted in a reduction in the expression of the cell-cell adhesion molecule, E-cadherin, and to a lesser degree, of desmoglein, along with increased invasion of Matrigel by human squamous cell carcinoma (SCC) cells in vitro. At higher concentrations, ETA stimulated the growth of SCC cells. As previously shown, n-6 EFAs (mainly 18:3 n-6, GLA), up-regulated the expression of E-cadherin and desmoglein. This is the first report showing that the abnormal 20:3 n-9 (Mead's acid) is a down regulator of antimetastatic E-cadherin and desmoglein expression.

Functional identification of a fatty acid delta5 desaturase gene from Caenorhabditis elegans

We have identified a cDNA from the nematode worm Caenorhabditis elegans that encodes a fatty acid delta5 desaturase. Saccharomyces cerevisiae expressing the full-length cDNA was able to convert di-homo-gamma-linolenic acid to arachidonic acid, thus confirming delta5 desaturation. The 1341 bp delta5 desaturase sequence contained an N-terminal cytochrome b5 domain and was located within a kilobase of the C. elegans delta6 desaturase on chromosome IV. With an amino acid identity of 45% it is possible that one of these genes arose from the other by gene duplication. This is the first example of a delta5 desaturase gene isolated from an animal.

Identification of Delta5-desaturase from Mortierella alpina by heterologous expression in Bakers' yeast and canola

A DNA fragment with homology to Delta6-desaturases from borage and cyanobacteria was isolated after polymerase chain reaction amplification of Mortierella alpina cDNA with oligonucleotide primers corresponding to the conserved regions of known Delta6-desaturase genes. This fragment was used as a probe to isolate a cDNA clone with an open reading frame encoding 446 amino acids from a M. alpina library. Expression of this open reading frame from an inducible promoter in Saccharomyces cerevisiae in the presence of various substrates revealed that the recombinant product had Delta5-desaturase activity. The effects of growth and induction conditions as well as host strain on activity of the recombinant Delta5-desaturase in S. cerevisiae were evaluated. Expression of the M. alpina Delta5-desaturase cDNA in transgenic canola seeds resulted in the production of taxoleic acid (Delta5,9-18:2) and pinolenic acid (Delta5,9,12-18:3), which are the Delta5-desaturation products of oleic and linoleic acids, respectively.

Fatty acid nutriture in hospitalized elderly women

OBJECTIVE

The aim of this study was to measure the fatty acid (FA) dietary intakes and the FA composition of plasma total lipids in a selected group of hospitalized elderly patients.

METHODS

Twenty-three women aged 76 to 99 years were recruited. FA were analyzed in 5-day duplicate portions and in plasma by gas liquid chromatography.

RESULTS

The hospitalized elderly women ingested an average of 5.22 megajoules (MJ) and 45.9 g of lipids per day. Polyunsaturated fatty acids (PUFA) represented 11.0% and saturated fatty acids (SFA) 53.6% of the lipid intake. Minimal recommendations for linoleic acid intake were reached in average, but 32% of the patients ingested less than 3 g of linoleic acid/d. Eighty-six percent received less than 0.5% of energy for alpha-linolenic acid and 64% had low intakes in very long-chain n-3 FA. In parallel, these patients presented several biochemical signs of essential fatty acids (EFA) insufficiency (decrease in linoleic acid, increase in monounsaturated fatty acids (MUFA), in n-7 FA and in indexes of delta-6 and delta-9 desaturase activities).

CONCLUSIONS

Hospitalized elderly patients have low PUFA intakes and show biochemical indices of EFA insufficiency. These patients might benefit from a nutritional supplementation providing both EFA and antioxidant micronutrients to limit the risk of skin troubles, immune system impairment and vascular disease often observed in institutionalized elderly subjects.

Toxicity antagonists in head and neck cancer

Clinical trials of altered fractionation and concurrent chemoradiation regimens have better elucidated the limits of both acute and late normal tissue toxicities in the head and neck. Acute effects on mucosal epithelium represent the principal barrier to intensification of radiation or chemoradiation schedules. Late soft tissue injury and organ dysfunction limit efforts to escalate radiation total dose. New insights into the cellular and molecular mechanisms of injury repair allow new strategies in the management and prevention of treatment-related toxicity. Toxicity antagonists are agents that directly interfere with the mechanism of toxicity or modulate the normal tissue response to injury. This article reviews 10 agents under development. Not only could such interventions reduce treatment-related morbidity, but they may also allow treatment intensification in advanced disease.

Comparative effects of short- and long-term feeding of safflower oil and perilla oil on lipid metabolism in rats

Diets high in linoleic acid (20% safflower oil contained 77.3% linoleic acid, SO-diet) and alpha-linolenic acid (20% perilla oil contained 58.4% alpha-linolenic acid, PO-diet) were fed to rats for 3, 7, 20, and 50 days, and effects of the diets on lipid metabolism were compared. Levels of serum total cholesterol and phospholipids in the rats fed the PO-diet were markedly lower than those fed the SO-diet after the seventh day. In serum and hepatic phosphatidylcholine and phosphatidylethanolamine, the proportion of n-3 fatty acids showed a greater increase in the PO group than in the SO group in the respective feeding-term. At the third and seventh days after the commencement of feeding the experimental diets, expressions of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA were significantly higher in the SO group than those in the PO group, although the difference was not observed in the longer term. There were no significant differences in the LDL receptor mRNA levels between the two groups through the experimental term, except 3-days feeding. These results indicate that alpha-linolenic acid has a more potent serum cholesterol-lowering ability than linoleic acid both in short and long feeding-terms.

Comparison of the fatty acid compositions in intraepithelial and infiltrating lesions of the cervix: part II, free fatty acid profiles

In the second part of this study, the emphasis is on the free fatty acids during cervical carginogenesis, since they may reflect active cell metabolism during this disease process. Lipids were extracted from biopsies of normal epithelial tissue (N) (n=36), cervical intraepithelial lesions (CIL) (n=47), and infiltrating lesions (Ca) (n=47) of the cervix. Samples, from which the free fatty acid compositions were determined, were saponified, methylated and analysed by GLC. In accordance with results obtained on total fatty acid compositions, essential fatty acid deficiency (EFAD) in the intraepithelial lesions, compared with normal tissue (linoleic acid, P< 0.01), and infiltrating lesions compared with intraepithelial lesions (linoleic acid and arachidonic acid, P< 0.01) were observed. High levels of oleic acid were also observed when infiltrating lesions were compared with normal tissue (P < 0.01). As previously mentioned by us in part I of this study, with regard to possible disturbances in metabolic pathways based on the total fatty acid profiles during stages of cervical cancer, EFAD is prevalent during cervical carcinogenesis. This EFAD in cancer cells may result in many defective cell mechanisms, since fatty acids are associated with biochemical events such as lipid peroxidation, signal transduction and immune responses. The high level of oleic acid in cancer cells is known to activate PKC and thus contribute to the continous growth stimulus thought to exist in malignant cells. From a therapeutic viewpoint, substantial changes in the fatty acid composition of the membranes can be produced in cancer cells by selective fatty acid supplementation strategies. At present, modifications of the fatty acid compositions of cell membranes represent an experimental model that has promoted increased understanding of lipid transportation, membrane remodelling, and the relationship between membrane lipids and membrane function. By addressing factors responsible for insufficient essential fatty acid levels, carginogenesis may be prevented or treated. The clinical feasibility of using modification of fatty acids in tumours or cancer by diet or perfusion as an adjunct to standard therapies should be tested.

Effect of a supplementary dietary evening primrose oil mixture on hoof growth, hoof growth rate and hoof lipid fractions in horses: a controlled and blinded trial

The lipid chemistry of the normal equine hoof, together with the effect of oral supplementation with an evening primrose oil mixture (EPOM) on its growth, growth rate and lipid content was assessed in a controlled and blinded feeding trial at the Defence Animal Centre. Twelve horses were paired as closely as possible according to sex, age, weight, height and colour and then one from each pair was randomly allocated to treatment or control groups. The treatment group received 30 ml of oral EPOM/day, otherwise the nutrition and management regimes were the same for all horses. No significant differences (P > 0.05) were seen between treatment and control groups for hoof horn growth or growth rate. However, there was a significant difference (P < 0.05) in hoof horn growth within the treatment group only between weeks 4 and 8 after the start of supplementation. The stratum medium contained significantly higher amounts of cholesterol ester (P < 0.05), triglycerides (P < 0.001) and free fatty acids (P < 0.05) than the periople. The periople contained significantly higher levels of free cholesterol and phospholipid (P < 0.001) than the stratum medium of the hoof wall. There were no significant differences (P > 0.05) between treatment and control groups for any of the lipid fractions measured for the stratum medium from the clippings of the hoof wall. However, there were differences in perioplic lipid analysis with significant increases (P < 0.05) in cholesterol esters and partial glycerides and a significant reduction (P < 0.001) in free cholesterol in the treatment group following supplementation.

Gustatory mechanisms for the detection of fat

Recent evidence suggests that free fatty acids may be one of the important stimuli used by taste receptor cells for the detection of fat. Consistent with this interpretation, the proteins necessary for the release and transport of lipophilic fatty acids are found in the oral cavity, and taste cells have recently been shown to contain fatty-acid-sensitive ion channels and transport molecules for the uptake of fatty acids.

Isolation of a Delta5-fatty acid desaturase gene from Mortierella alpina

Arachidonic acid (C20:4 Delta5,8,11,14) is a polyunsaturated fatty acid synthesized by the Delta5-fatty acid desaturation of di-homo-gamma-linolenic acid (C20:3 Delta8,11,14). In mammals, it is known to be a precursor of the prostaglandins and the leukotrienes but it is also accumulated by the filamentous fungus Mortierella alpina. We have isolated a cDNA encoding the Delta5-fatty acid desaturase from M. alpina via a polymerase chain reaction-based strategy using primers designed to the conserved histidine box regions of microsomal desaturases, and confirmed its function by expression in the yeast Saccharomyces cerevisiae. Analysis of the lipids from the transformed yeast demonstrated the accumulation of arachidonic acid. The M. alpina Delta5-desaturase is the first example of a cloned Delta5-desaturase, and differs from other fungal desaturases previously characterized by the presence of an N-terminal domain related to cytochrome b5.

Effect of dietary arachidonic acid on metabolism of deuterated linoleic acid by adult male subjects

The influence of dietary supplementation with 20:4n-6 on uptake and turnover of deuterium-labeled linoleic acid (18:2n-6[d2]) in human plasma lipids and the synthesis of desaturated and elongated n-6 fatty acids from 18:2n-6[d21 were investigated in six adult male subjects. The subjects were fed either a high-arachidonic acid (HIAA) diet containing 1.7 g/d or a low-AA (LOAA) diet containing 0.21 g/d of AA for 50 d. Each subject was then dosed with about 3.5 g of 18:2n-6[d2] as the triglyceride (TG) at 8:00 A.M., 12:00, and 5:00 P.M. The total 18:2n-6[d21] fed to each subject was about 10.4 g and is approximately equal to one-half of the daily intake of 18:2n-6 in a typical U.S. male diet. Nine blood samples were drawn over a 96-h period. Methyl esters of plasma total lipid (TL), TG, phospholipid, and cholesterol ester were analyzed by gas chromatography-mass spectroscopy. Dietary 20:4n-6 supplementation did not affect uptake of 18:2n-6[d2] in plasma lipid classes over the 4-d study period nor the estimated half-life of 24-36 h for 18:2n-6[d2]. The percentages of major deuterium-labeled desaturation and elongation products in plasma TL, as a percentage of total deuterated fatty acids, were 1.35 and 1.34% 18:3n-6[d2]; 0.53 and 0.50% 20:2n-6[d2]; 1.80 and 0.92% 20:3n-6[d2] and 3.13 and 1.51% 20:4n-6[d2] for the LOAA and HIAA diet groups, respectively. Trace amounts (<0.1%) of the 22:4n-6[d2] and 22:5n-6[d2] metabolites were present. Plasma TL concentration data for both 20:3n-6[d2] and 20:4n-6[d2] were 48% lower (P < 0.05) in samples from the HIAA diet group than in samples from the LOAA diet group. For a normal adult male consuming a typical U.S. diet, the estimated accumulation in plasma TL of 20:4n-6 synthesized from 20 g/d (68 mmole) of 18:2n-6 is 677 mg/d (2.13 mmole). Dietary supplementation with 1.5 g/d of 20:4n-6 reduced accumulation of 20:4n-6 synthesized from 20 g/d of 18:2n-6 to about 326 mg/d (1.03 mmole).

Growth, mortality, tissue histopathology and fatty acid compositions, eicosanoid production and response to stress, in juvenile turbot fed diets rich in gamma-linolenic acid in combination with eicosapentaenoic acid or docosahexaenoic acid

Three diets containing either borage oil (BO) and southern hemisphere fish oil Marinol (MO), or BO and tuna orbital oil (TO), or a northern hemisphere fish oil (FO) were fed to duplicate groups of turbot (Scophthalmus maximus) of initial mean weight 1.2 g for a period of 12 weeks. The BO/MO and BO/TO diets were enriched in gamma-linolenic (18:3n-6, GLA) and eicosapentaenoic (20:5n-3, EPA) acids, and GLA and docosahexaenoic acid (22:6n-3, DHA), respectively. No differences were observed in final weights or growth rates, either between duplicate tanks or between dietary treatments. Half of the FO-fed fish sampled showed a histopathological lesion indicative of lipoid liver degeneration while the other treatments only showed a slight incidence of the same pathology. The fatty acid compositions of carcass and tissues broadly reflected the dietary input. In general, fish fed the BO/MO diet had increased levels of 18:2n-6, 18:3n-6, 20:3n-6 and 20:5n-3, but a lower level of 22:6n-3, compared to fish fed FO. In fish fed the BO/TO diet, levels of 18:2n-6, 18:3n-6, 20:3n-6 and 20:4n-6 were increased while levels of 20:5n-3 and 22:5n-3 were reduced, compared to fish fed FO. Concentrations of thromboxanes B (TXB) and leukotrienes B (LTB), derived from 20:4n-6 and 20:5n-3, were measured in plasma and stimulated blood cells. Levels of TXB2 were greatest in fish fed the BO/TO diet compared to both other treatments, while LTB4 was decreased in fish fed the BO/MO diet compared to both other treatments. In a stress test which involved anaesthesia followed by measurement of recovery times, fish fed the BO/MO diet had significantly lower recovery times compared to fish fed the FO diet.

Differential modulation by dietary n-6 or n-9 unsaturated fatty acids on the development of two murine mammary gland tumors having different metastatic capabilities

It is widely known that dietary lipids can modify the ability of different cancers to grow up and metastasize, especially mammary gland tumors. However, it is still unclear whether n-6 fatty acids behave as tumor promoters in this gland cell population. The effect of different nutritional polyunsaturated fatty acids (PUFAs) on tumor growth parameters of two transplantable murine mammary gland adenocarcinomas of low and high metastatic ability was tested on hosts fed diets with corn oil (CO) rich in 18:2n-6, evening primrose oil (EPO) containing 18:3n-6 (GLA) and a third formula supplemented with olein (O) 18:1n-9, which induces an essential fatty acid deficiency (EFAD). Tumor growth parameters were not adversely affected in the corn oil group with respect to stock-fed controls. Furthermore, metastatic spreading diminished in this group. EPO showed a moderate antitumor activity whereas the n-9-enriched diet showed no clear-cut effects. In both mammary gland tumors, n-6 fatty acid-rich lipids formulae, containing GLA and linoleic acid, were not tumor promoters. On the contrary, both exhibited anticancer activity.

The membrane phospholipid hypothesis as a biochemical basis for the neurodevelopmental concept of schizophrenia

The neurodevelopmental hypothesis of schizophrenia is becoming an important feature of research in the field. However, its major drawback is that it lacks any biochemical basis which might draw the diverse observations together. It is suggested that the membrane phospholipid hypothesis can provide such a biochemical basis and that the neurodevelopmental phospholipid concept offers a powerful paradigm to guide future research.

Schizophrenia: the illness that made us human

Any hypotheses concerning the origins of humans must explain many things. Among these are: 1, the growth in brain size around two million years ago; 2, the presence of subcutaneous fat; 3, the near absence of change or cultural progress for around 2 million years after the brain grew in size; 4, the cultural explosion which began somewhere between fifty thousand and one hundred thousand years ago with the emergence of art, music, religion and warfare; 5, the further cultural explosion around ten thousand to fifteen thousand years ago which developed with the emergence of agriculture and which has continued since. Since the brain, like subcutaneous fat, is particularly rich in lipids, and since the microconnections of the brain are substantially lipid in nature, it is suggested that changes in lipid metabolism are what differentiated humans from the great apes. The growth in brain size and in the quality of subcutaneous adipose tissue may have occurred because of changes in the proteins which regulate the rate of delivery of fatty acids to tissues, notably lipoprotein lipases and fatty acid binding proteins. The creativity which occurred one hundred thousand years ago may have resulted from changes in phospholipid-synthesizing, -remodelling and -degrading enzymes which largely determine the microconnectivity of neurons. Family studies and adoption studies indicate that schizophrenia in a family member is associated with an increased risk of the illness in other family members. It is also associated with an increased risk of schizotypy, manic-depression, dyslexia, sociopathy and psychopathy. On the other hand it is also an indication of an increased likelihood of high creativity, leadership qualities, achievements in many fields, high musical skills and an intense interest in religion. I propose that the characteristics which entered the human race about one hundred thousand years ago and which ended around two million years of cultural near-stagnation are precisely those shown by the families of people with schizophrenia. I propose that these features are caused by variations in phospholipid biochemistry which are responsible both for schizophrenia and for our humanity. This would help to explain why schizophrenia is present to approximately the same degree in all races. It is the illness which made us human prior to the separation of the races.

Abnormal content of n-6 and n-3 long-chain unsaturated fatty acids in the phosphoglycerides and cholesterol esters of parahippocampal cortex from Alzheimer's disease patients and its relationship to acetyl CoA content

The long-chain fatty acid composition of cholesterol esters, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI) from parahippocampal cortex of Alzheimer's disease (AD) patients and control subjects was examined. In general the PC fraction contained less polyunsaturated long-chain fatty acids than did PE, PS or PI. Of the n-6 polyunsaturated long-chain fatty acids, PI contained the greatest incorporation of these acids followed by PE. There were significant differences between controls and AD patients in total n-6 EFAs. Arachidonic acid (C20:4n-6) was the predominant fatty acid of this family found to be present. In AD, PE and PS showed a deficit of adrenic acid (C22:4n-6) content and PE also contained less arachidonic acid. In AD subjects, the cholesterol esters contained significantly less n-3 polyunsaturated fatty acids with, specifically, a reduction in alpha-linolenic acid. Acetyl CoA content of hippocampal cortex was greater in AD patients than in control subjects indicating either an increased extent of oxidative metabolism or a failure to utilise acetyl CoA for anabolic processes. Abnormal magnitude of oxidative processes could give rise to the biosynthesis of PE and PS species containing less n-6 polyunsaturated fatty acids than occurs in control subjects.

Calcium metabolism, osteoporosis and essential fatty acids: a review

Essential fatty acid (EFA)-deficient animals develop severe osteoporosis coupled with increased renal and arterial calcification. This picture is similar to that seen in osteoporosis in the elderly, where the loss of bone calcium is associated with ectopic calcification of other tissues, particularly the arteries and the kidneys. Recent mortality studies indicate that the ectopic calcification may be considerably more dangerous than the osteoporosis itself, since the great majority of excess deaths in women with osteoporosis are vascular and unrelated to fractures or other bone abnormalities. EFAs have now been shown to increase calcium absorption from the gut, in part by enhancing the effects of vitamin D, to reduce urinary excretion of calcium, to increase calcium deposition in bone and improve bone strength and to enhance the synthesis of bone collagen. These desirable actions are associated with reduced ectopic calcification. The interaction between EFA and calcium metabolism deserves further investigation since it may offer novel approaches to osteoporosis and also to the ectopic calcification associated with osteoporosis which seems to be responsible for so many deaths.

Effects of dietary gamma-linolenic acid-rich borage oil combined with marine fish oils on tissue phospholipid fatty acid composition and production of prostaglandins E and F of the 1-, 2- and 3-series in a marine fish deficient in delta5 fatty acyl desaturase

The effects of gamma-linolenic acid-rich borage oil (BO), in combination with different marine oils, namely an eicosapentaenoic acid (EPA) rich oil (MO) or a DHA-rich oil (TO), on tissue fatty acid composition and prostaglandin production were investigated in turbot, a species which lacks appreciable delta5 fatty acyl desaturase activity. The juvenile turbot grew well on the experimental diets and there were no significant differences in final weights between dietary treatments. Irrespective of the marine oil component, both the BO-containing diets increased tissue phospholipid levels of 18:2n-6 and 18:3n-6, and their respective elongation products, 20:2n-6 and 20:3n-6, compared to fish fed a control diet containing a standard Northern hemisphere fish oil. Both the BO-containing diets increased the production of 1-series prostaglandins (PG), this being observed across all tissues investigated with PGF and especially PGE. The BO/MO diet also reduced 20:4n-6 in tissue phospholipids without affecting 20:5n-3, whereas the BO/TO combination decreased 20:5n-3 but increased 20:4n-6. The production of 2-series and 3-series PGs was also altered by the dietary treatments but the changes were less dependent upon the tissue levels of their respective precursor fatty acids, 20:4n-6 and 20:5n-3. The BO-containing diets had very significant effects on gross fatty acid compositions of the phospholipids including increased proportions of saturated fatty acids and n-6 polyunsaturated fatty acids (PUFA) and decreased proportions of monounsaturated fatty acids and n-3 PUFA. Overall, this study shows that eicosanoid production in turbot tissues can be influenced by dietary fatty acids, not only by changes in the absolute and relative levels of specific eicosanoid precursor PUFA in tissue phospholipids, but also by general effects on membrane composition, structure and function induced by gross fatty acid compositional changes.

Effect of evening primrose oil on gastric ulceration and secretion induced by various ulcerogenic and necrotizing agents in rats

The evening primrose oil (EPO) commercially known as Callanish evening primrose oil (omega-6 polyunsaturated fatty acid) is linoleic acid (LA) and gamma-linolenic acid (GLA)-enriched oil obtained from the seeds of Oenothera biennis L. (Fam. Onagraceae). EPO was investigated for its ability to protect the gastric mucosa against injuries caused by pylorus ligation, non-steroidal anti-inflammatory drugs (NSAIDs; aspirin, indomethacin and phenylbutazone), hypothermic restraint stress and necrotizing agents [0.6 M HCl, 0.2 M NaOH, 25% NaCl or 80% (v/v) aqueous ethanol]. It was administered by gastric intubation at doses of 5 and 10 ml/kg body weight to rats fed standard chow diet. An additional group of animals was given the same amount of corn oil in each experimental model studied. The results showed that EPO at the doses of 5 and 10 ml/kg body weight provided significant protection in various experimental models used. It produced a significant inhibition of gastric mucosal damage induced by pylorus ligation, NSAIDs, or hypothermic restraint ulcers. EPO also had a marked cytoprotective effective effect against all necrotizing agents used in this study. The results suggest that EPO rich in LA and GLA possesses both antisecretory and anti-ulcerogenic effects.

Modulation of the cell kinetics of pig skin by the topical application of evening primrose oil or Lioxasol

The daily topical application of two compounds, a cream containing 10% evening primrose oil (EPO) and Lioxasol (a compound used clinically to treat radiation burns), resulted in increased cell proliferative activity in the skin of female Large White pigs. The effect was most pronounced in the case of the EPO based cream, and was comparable in magnitude with that observed in a previous study on pig skin using orally administered EPO. There was an increase in the size of the rete pegs in the epidermis by 6 weeks after the start of application of the EPO cream. However, this did not translate into an increase in the total thickness of the viable epidermis (excluding the stratum corneum) due to a reduction in the density of rete pegs, from 2 weeks after treatment. Lioxasol had no overall effect on the size of the rete pegs. The labelling index (LI) of cells in the basal layer of the epidermis of pigs receiving a daily topical application of EPO increased progressively with time from the start of application. The LI was maximal (17.9 +/- 2.4%) at the end of the observation period (8 weeks) at which time it was a factor of approximately 2 higher than in the basal layer prior to treatment. A considerably less marked increase in the LI of the basal layer was seen after the application of Lioxasol. The overall increase was approximately 20%, relative to the LI in the untreated epidermis. Labelled cell nuclei were also counted in the papillary dermis. After the application of the EPO cream, no significant increase in the number of labelled cells was observed until week 8, at which time values were approximately twice those in untreated skin. In Lioxasol treated skin the effect on the numbers of labelled cells in the papillary dermis was more immediate, with a approximately 60% increase at 2 weeks. This enhanced level of labelling was maintained until the end of the observation period of 10 weeks. Studies on the cell kinetics of the skin using the alcohol component of the Lioxasol preparation suggested that alcohol rather than Lioxasol was the most significant ingredient. It was concluded that the EPO cream merited further evaluation as a potential modulator of skin response to ionizing radiation.

Capillary supercritical fluid chromatography--atmospheric pressure chemical ionization mass spectrometry of gamma- and alpha-linolenic acid containing triacylglycerols in berry oils

The effect of the gamma-linolenic acid (18:3n-6) residue on the elution of triacylglycerols on a 25% cyanopropyl-25% phenyl-50% methylpolysiloxane stationary phase was confirmed by using capillary supercritical fluid chromatography-atmospheric pressure chemical ionization mass spectrometry [cSFC-(APCI)MS]. The general elution rule on this stationary phase is that triacylglycerols having the same ACN + 2n value coeluted (ACN = acyl carbon number and n = combined number of double bonds in the acyl chains). The different effect of gamma- and alpha-linolenic acid residues on the retention of triacylglycerols and the use of cSFC-(APCI)MS allowed the study of the number of different linolenic acid residue isomer combinations in triacylglycerols with an identical ACN and degree of unsaturation. Stearidonic acid (18:4n=3) residue was found to have a similar effect on the retention behavior of triacylglycerols as that of gamma-linolenic acid residue. The abundance of the [M - RCOO]+ ion, formed by the loss of one fatty acid moiety of a triacylglycerol, was found to be clearly higher in the case of gamma-isomer of the linolenic acid than that of alpha-isomer in the identical regiospecific position. This indicates that the distance of the double bonds from the glycerol backbone in the acyl chain affects the stability of a triacylglycerol molecule in the (APCI)MS system. The triacylglycerol composition and the fatty acid combinations of triacylglycerols were found to be almost identical in black currant (Ribes nigrum) and alpine currant (R. alpinum) seed oils.