Ontogenesis of lipids in chick embryo retina

PURPOSE: The effects of embryonic development on lipid composition in the retina were studied in 7, 11, 15, and 18-day-old chick embryos and newly hatched chicks. METHODS: The proportions of phospholipids, free and esterified cholesterol, diacylglycerides, and free fatty acids were determined using the Iatroscan TLC/FID procedure. Gas chromatography and mass spectrometry were used to determine the fatty acid composition. RESULTS: The major phospholipid species were phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, lysophosphatidylcholine, and sphingomyelin. Concentrations of the analyzed components have been related to the chronology of concrete stages of retinal development. The fatty acid composition of the total lipids, (n-6):(n-3) and saturated: unsaturated fatty acid ratios, and other parameters are reported. The proportions of total saturated and total monounsaturated fatty acids decreased very little from day 7 to hatching, whereas total polyunsaturated fatty acids nearly doubled over the same period. The increase in C18:2(n-6) from day 11 onwards was not followed by a similar increase in C20:4(n-6), hence the C20:4 to C18:2 ratio decreased with age. CONCLUSIONS: The cholesterol:phospholipid ratio decreased from day 7 to day 15 and increased from day 15 to hatching. High proportions of esterified cholesterol, very probably originating in the retinal pigment epithelium, were also recorded. Total saturated and monounsaturated fatty acids decreased, while polyunsaturated fatty acids increased during the period of initial retinal growth.     

Net transfer and incorporation of yolk n-3 fatty acids into developing chick embryos

The effect of egg yolk fatty acid composition on the uptake and utilization of essential n-6 and n-3 fatty acids by the developing chick embryo was studied. Eggs were enriched with n-9, n-3, or n-6 fatty acids by incorporating sunflower seed high in oleic acid (C18:1 n-9), flax seed rich in linolenic acid (C18:3 n-3), or sunflower seed high in linoleic acid (C18:2 n-6) into the laying hen diets. Fertile eggs were collected and incubated. The fatty acid composition of eggs and newly hatched chicks were compared. Feeding diets containing flax seed increased (P < .05) total n-3 fatty to 528.4 mg compared with 53.9 and 39.3 mg for eggs from hens fed diets with high oleic acid or regular sunflower seed, respectively. Levels of C18:2 n-6 and monounsaturated fatty acids were higher in eggs from hens fed diets containing regular or high oleic acid sunflower seeds. Dietary fat did not influence the total lipid content of the egg yolk or total lipids of chick tissues. The fatty acid composition of the hatched progeny was significantly altered by egg yolk lipids. However, the percentage incorporation of essential n-6 and n-3 fatty acids into the progeny increased when yolk sources of these fatty acids were low. The developing chick embryo appeared to preferentially take up docosahexaenoic acid and arachidonic acid from the yolk lipids. Evidence also suggests that conversion of C18:2 n-6 and C18:2 n-3 to longer chain n-3 or n-6 fatty acids occurs during the incubation period.     

Biomechanic effects of a contralateral shoe-lift on walking with an immobilized knee

The molecular species compositions of the main diacyl phosphoglyceride classes and ether-linked subclasses from sperm of three species of fish, sea bass Dicentrarchus labrax, Atlantic salmon Salmo salar and Chinook salmon Onchorhynchus tsawytscha, were determined. The phospholipids from sperm were highly unsaturated, dipolyunsaturated fatty acid (diPUFA) molecular species comprised 64.6 to 71.8% of phosphatidylserine (PS), 10.1 to 17.4% of phosphatidylethanolamine (PE), and 3.3 to 10.1% of phosphatidylcholine (PC). In sea bass sperm, di22:6n-3 phospholipid was the predominant diPUFA molecular species, but in both salmon species 22:5n-3/22:6n-3 was also a major constituent of PS. Phospholipids containing 22:6n-3 dominated in sea bass sperm with 16:0/22:6n-3 as a major component of PC and PE, and 18:0/22:6n-3 of PE and PS in addition to di22:6n-3 in the latter two classes. In contrast, both salmon species contained much more 20:5n-3 and less 22:6n-3 so that saturated/20:5n-3 and monounsaturated/20:5n-3 molecular species were more abundant than the corresponding molecules containing 22:6n-3. Ether-linked lipids comprised 11.3-36.3% of choline and ethanolamine phosphoglycerides in each fish species. Molecular species containing 22:6n-3 were the major components of 1-O-alkyl-2-acyl-glycerophosphocholine, especially 16:0a/22:6n-3 in sea bass and 18:1a/22:6n-3 in the two salmon species, while in 1-O-alk-1'-enyl-2-acyl-glycerophosphoethanolamine, 16:0a/22:6n-3 was the major component in both salmon and 18:0a/22:6n-3 in sea bass with 18:1a/22:6n-3 abundant in all three species. In Atlantic salmon 1-O-alkyl-2-acyl-glycerophosphoethanolamine comprised 24.6% of ethanolamine glycerophospholipids which were predominantly 16:0a/22:6n-3 and 18:1a/22:6n-3. Phosphatidylinositol from sperm was dominated by stearoyl/C20 PUFA molecular species, in sea bass overwhelmingly 18:0/20:4n-6, while in both salmon species 18:0/20:4n-6 and 18:0/20:5n-3 were equally abundant.     

Uneven distribution of desmosterol and docosahexaenoic acid in the heads and tails of monkey sperm

Previously we demonstrated high concentrations of desmosterol and docosahexaenoic acid (DHA, 22:6 n-3) in monkey testes and sperm. Desmosterol, a cholesterol precursor, is not present elsewhere in the body. High concentrations of DHA are found elsewhere only in the retina and brain. To examine the distribution of these compounds in the heads and tails of sperm, we separated them and determined their sterol, fatty acid, and phospholipid molecular species composition. Desmosterol predominated in tails (134.4 vs. 1.7 microg/10(9) cells in heads). The cholesterol content was also greater in the tails (66.2 vs. 30.3 microg/10(9) cells in heads). Sperm tails had more polyunsaturated fatty acids than the heads (34.1 vs. 12.1% of total fatty acids) which resulted mainly from the higher contents of DHA (19.6 vs. 1.1%) and arachidonic acid (20:4 n-6) (6.4 vs. 1.6%) in the tails. These differences in fatty acid composition occurred mainly in phospholipids: phosphatidyl choline and phosphatidyl ethanolamine for n-3 fatty acids and phosphatidyl serine and cardiolipin for n-6 fatty acids. Fifteen phospholipid molecular species were identified. Sperm tails had more molecular species containing unsaturated fatty acids than the heads. Our results reveal the large differences in membrane lipid composition between the heads and tails of sperm. Most (99%) of the desmosterol and DHA in sperm is located in the tail. These differences may be responsible for the different functions of these two components of sperm. The large number of double bonds in DHA, six, and in desmosterol, two, may contribute to the membrane fluidity necessary for the motility of the sperm tails.     

Changes in adipose tissue composition in malnourished patients before and after liver transplantation: a carbon-13 magnetic resonance spectroscopy and gas-liquid chromatography study

We investigated adipose tissue fatty acid composition in 22 moderately to severely malnourished patients with cirrhosis and in 22 healthy volunteers by in vivo carbon-13 magnetic resonance spectroscopy (MRS). Gas-liquid chromatography (GLC) of adipose tissue samples was also performed in 11 of the patients and in 4 volunteers. In vivo 13C magnetic resonance spectra were obtained from the subcutaneous adipose tissue before and after eight weeks following orthotopic liver transplantation (OLT). Adipose tissue biopsy samples were obtained for GLC analysis at the time of transplantation in the patients and at inguinal hernia repair in the 4 volunteers. No significant differences were found in the subcutaneous adipose tissue total-saturated, -polyunsaturated or -monounsaturated fatty acid composition between patients and healthy volunteers by in vivo 13C MRS. GLC analysis of adipose tissue samples confirmed that total levels of saturated, poly-, and monounsaturated fatty acids remained the same but revealed significant differences in levels of individual fatty acids, particularly n-3 fatty acids (total n-3, cirrhotics: .84% +/- .07% vs. controls: 1.36% +/- .13%, P < .01). Eight weeks following transplantation, recipients showed a considerable increase in body mass (pretransplantation: 59.3 +/- 3.2 vs. posttransplantation: 63.2 +/- 3 kg, P < .01). 13C MRS revealed a significant increase in saturated fatty acids (pretransplantation: 21.6 +/- 2.8 vs. posttransplantation: 25.5% +/- 1.2%, P < .05) and a significant decrease in unsaturated fatty acids. The application of noninvasive MRS techniques may be important to identify the differential uptake of fats, examining both specific fatty acids and different body fat compartments. In the future, this may be useful in optimizing the dietary management of severely malnourished patients with chronic liver disease before liver transplantation.     

Dietary monounsaturated fatty acids promote aortic atherosclerosis in LDL receptor-null, human ApoB100-overexpressing transgenic mice

In mice with genetically engineered high levels of plasma low density lipoprotein (LDL), we tested the hypothesis that an increase in the dietary content of monounsaturated fatty acids but not of polyunsaturated fatty acids would promote atherosclerosis. The mouse model used was an LDL receptor-null, human apoB100-overexpressing strain. Six experimental groups of 19 to 38 mice of both sexes were established when the animals had reached 8 weeks of age. For the next 16 weeks, individual groups were fed either a commercial diet or prepared diets including fat as 10% of energy, with 5 different fatty acid enrichment patterns including the following: saturated (sat), cis and trans monounsaturated (mono), and n-3 and n-6 polyunsaturated (poly). Highly significant differences (ANOVA, P<0. 0001) in LDL cholesterol (in mg/dL) were found, with the rank order at 16 weeks being trans mono (mean, 1390)>sat (922)=cis mono (869)=n-6 poly (868)>n-3 poly (652)>commercial diet (526). Significant elevations in very low density lipoprotein cholesterol were also found in the trans and cis mono and sat groups, and triacylglycerol concentrations were also elevated in all groups. High density lipoprotein cholesterol concentrations were consistently low (20 to 50 mg/dL) in all groups. Highly significant differences (ANOVA, P<0.0001) in atherosclerosis, quantified by measurement of aortic cholesteryl ester concentration (mg/g protein) among dietary fatty acid groups were found, with the order being trans mono (mean, 50.4)>sat (35.6)=cis mono (34.6)>n-6 poly (18. 3)=n-3 poly (9.7)=commercial diet (7.8). Therefore, in this mouse model of hypercholesterolemia, dietary cis or trans monounsaturated fat did not protect against atherosclerosis development, whereas aortic atherosclerosis in either of the polyunsaturated fat groups was significantly less than in the saturated fat group.     

Fatty acid composition of fertilization-failed human oocytes

The aim of the study was to assess the fatty acid composition of human fertilization-failed oocytes. A total of 150 unfertilized oocytes from 43 women undergoing in-vitro fertilization (IVF) were analysed using capillary gas chromatography. The majority of fatty acids were saturated (79.22%), of which stearic (38.65%) and palmitic (32.66%) acids were the most abundant. Of the monounsaturated fatty acids (14.27%) oleic acid was the most abundant (9.77%). Polyunsaturated fatty acids comprised 6.50% of fatty acids, the n-6:n-3 ratio being 7.73. The ratio of eicosapentaenoic acid:docosahexaenoic acid was approximately 5. It is concluded that the most common fatty acids in human unfertilized oocytes are either saturated or monounsaturated fatty acids, whose main function is to provide an energy source. A number of differences in fatty acid composition were observed, in comparison with other biological samples. In particular, stearic and eicosapentaenoic acids were more prominent, and oleic and linoleic acids were less prominent; this may reflect some specific peculiarity of oocyte metabolism.     

Dietary fatty acid profile affects endurance in rats

Typically athletes are advised to increase their consumption of carbohydrates for energy and, along with the general population, to reduce consumption of saturated fats. It is now recognized that fats are not identical in their influence on metabolism, and we argue that the composition of the polyunsaturated fat component should not be ignored. The aim of this study was to manipulate the dietary fatty acid profile in a high-carbohydrate diet in order to investigate the effect of dietary polyunsaturates on submaximal endurance performance in rats. Rats were fed one of three isoenergetic diets containing 22 energy percentage (E%) fat for 9 wk. The diets comprised an essential fatty acid-deficient diet (containing mainly saturated fatty acids); a diet high in n-6 fatty acids, High n-6; and a diet enriched with n-3 fatty acids, High n-3. Submaximal endurance in rats fed the High n-3 diet was 44% less than in rats fed the High n-6 diet (P < 0.02). All rats were then fed a standard commercial laboratory diet for a 6-wk recovery period, and their performances were reevaluated. Although endurance in all groups was lower then at 9 wk, it was again significantly 50% lower in the High n-3 group than the High n-6 group (P < 0.005). Although n-3 fats are considered beneficial for cardiovascular health, they appear to reduce endurance times, and their side effects need to be further investigated.     

Dietary (n-3) and (n-6) polyunsaturated fatty acids rapidly modify fatty acid composition and insulin effects in rat adipocytes

The influence of dietary (n-3) compared with (n-6) polyunsatured fatty acids (PUFA) on the lipid composition and metabolism of adipocytes was evaluated in rats over a period of 1 week. Isocaloric diets comprised 16.3 g/100 g protein, 53.8 g/100 g carbohydrate and 21.4 g/100 g lipids, the latter containing either (n-3) PUFA (32.4 mol/100 mol) or (n-6) PUFA (37.8 mol/100 mol) but having identical contents of saturated, monounsaturated and total unsaturated fatty acids and identical polyunsaturated to saturated fatty acid ratios and double bond indexes. Despite comparable food intake, significantly smaller body weight increments and adipocyte size were observed in rats of the (n-3) diet group after feeding for 1 wk. Rats fed the (n-3) diet also had significantly lower concentrations of serum triglycerides, cholesterol and insulin compared with those fed the (n-6) diet, although levels of serum glucose and free fatty acids did not differ in the two dietary groups. In the (n-6) diet group, the (n-6) and (n-3) PUFA contents of plasma triglycerides, free fatty acids and phospholipids were 30-60% higher and 60-80% lower, respectively, than in the (n-3) diet group, whereas adipocyte plasma membrane phospholipids showed a significantly higher unsaturated to saturated fatty acid ratio and greater fluidity. Glycerol release in response to noradrenaline was significantly higher in the adipocytes of rats fed the (n-3) diet, whereas the antilipolytic effect of insulin generally did not differ in the two groups. Finally, insulin stimulated the transport of glucose and its incorporation into fatty acids to a lesser extent in adipocytes of (n-3) diet fed rats compared with (n-6) diet fed rats. This reduction in the metabolic effects of insulin in rats fed a (n-3) diet for 1 wk could be related to smaller numbers and a lower binding capacity of the insulin receptors on adipocytes and/or to a lesser degree of phosphorylation of the 95 kDa beta subunit of the receptor. In conclusion, dietary intake for 1 wk of (n-3) rather than (n-6) PUFA is sufficient to induce significant differences in the lipid composition and metabolic responses to insulin of rat adipocytes.     

Changes in plasma and colonic mucosa fatty acid profiles in rats with ulcerative colitis induced by trinitrobenzene sulfonic acid

Polyunsaturated fatty acids have a key role in the pathogenesis of inflammatory bowel disease since some of the arachidonic acid-derived eicosanoids have been found to be increased in inflamed intestinal mucosa in the acute phase of human disease. The aim of this study was to prospectively assess plasma and colon mucosa fatty acid patterns in rats with experimental ulcerative colitis. Twenty rats were treated with trinitrobenzene sulfonic acid and 20 with NaCl; two groups were killed after one week and two after two weeks to evaluate colon damage. Plasma was obtained by aortic puncture and colonic mucosa was scraped off and the fatty acid pattern was determined by gas-liquid chromatography. Total, saturated, and monounsaturated plasma fatty acids were significantly higher in both periods of ulcerative colitis as compared to controls. Plasma n-6 fatty acids were increased after treatment, but no significant changes were observed concerning to n-3 fatty acids. With regard to colon mucosa, saturated and monounsaturated fatty acids did not change because of the disease; however, n-6 fatty acids decreased in the first week and increased in the second week and n-3 fatty acids were increased. Changes on the fatty acid distribution in plasma did not parallel to those of colonic mucosa except for 22:6(n-3). We have also found that experimental ulcerative colitis induced by trinitrobenzene sulfonic acid reproduces many of the features related to changes in plasma and colon mucosa fatty acids observed in the human disease.     

Fatty acid composition of human brain phospholipids during normal development

The fatty acid composition of phosphatidylethanolamine (PE), ethanolamine plasmalogens (EPs), phosphatidylserine (PS), phosphatidylcholine (PC), and sphingomyelin was studied in 22 human forebrains, ranging in age from 26 prenatal weeks to 8 postnatal years. Phospholipids were separated by two-dimensional TLC, and the fatty acid methyl esters studied by capillary column GLC. Docosahexaenoic acid (22:6n-3) increased with age in PE and PC, whereas arachidonic acid (20:4n-6) remained quite constant. In EP, 22:6n-3 increased less markedly than 20:4n-6, adrenic (22:4n-6) and oleic (18:1n-9) acids being the predominant fatty acids during postnatal age. In PS, 18:1n-9 increased dramatically throughout development, and 20:4n-6 and 22:4n-6 increased only until approximately 6 months of age. Although 22:6n-3 kept quite constant during development in PS, its percentage decreased due to the accretion of other polyunsaturated fatty acids (PUFAs). As a characteristic myelin lipid, sphingomyelin was mainly constituted by very long chain saturated and monounsaturated fatty acids. Among them, nervonic acid (24:1n-9) was the major very long chain fatty acid in Sp, followed by 24:0, 26:1n-9, and 26:0, and its accretion after birth was dramatic. As myelination advanced, 18:1n-9 increased markedly in all four glycerophospholipids, predominating in EP, PS, and PC. In contrast, 22:6n-3 was the most important PUFA in PE in the mature forebrain.     

The influence of gastric juice acidity on the occurrence of esophageal reflux]

Protective properties of n-3 and n-6 polyunsaturated, monosaturated and saturated fatty acids (respectively, n-3 PUFA, n-6 PUFA, MUFA and SFA) against ethanol induced hemorrhagic gastric mucosal lesions were compared. Female Wistar rats (90-100 g) were fed to four weeks semisyntethic diets containing 9% butter (SFA-diet), 6% butter and 3% olive oil (MUFA-diet), 6% butter and 3% sunflower oil (n-6 PUFA-diet) or 6% butter and 3% concentrate of n-3 PUFA ethyl esters (n-3 PUFA-diet). One group of rats received a non-lipid diet. Under all types of lipid containing diets, development of ethanol-induced hemorrhagic gastric mucosal lesions was reduced in compared with non-lipid diet. Cytoprotective effect of n-3 PUFA-E was greater than MUFA and SFA, but smaller than n-6 PUFA.     

Quality of care in outpatient clinic for female diseases. A study of the perception of patients with infertility problems

Influence of dietary w-6 and w-3 polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA) and saturated fatty acids (SFA) on development of rat paw edema induced by dextran subplantar injection was studied. Female Wistar rats the initial weight 150-160 g were bed fo four weeks diets containing as lioid components 6% butter and 3% sunflower oil (w-6 PUFA-diet), 6% butter and 3% fish oil (w-3 PUFA-diet), 6% butter and 3% olive oil (MUFA-diet) or butter (SFA-diet). One group of rats received a non-lipid diet. The development of rat paw edema was reduced under the w-3 PUFA-diet in comparison with the w-6 PUFA-diet, but more intensive then under the non-lipid diet. No differences were detected in effects on inflammation induced w-3 PUFA-, MUFA-, and SFA-diets.     

Which operations can be done without general anesthesia?

The fatty acid composition of erythrocytes, platelets, and serum lipids was compared between subjects who had been eating a strict uncooked vegan diet ("living food") for years and omnivore controls. The vegan diet contains equal amounts of fat but more monounsaturated and polyunsaturated and less saturated fatty acids than the mixed diet of the control group. In vegans, the proportion of linoleic acid was greater in all lipid fractions studied. Also, the levels of other n-6 fatty acids were greater, with the exception of arachidonic acid levels, which were similar in most fractions. In erythrocytes, platelets and serum phospholipid fractions, this increase was mainly at the expense of the n-3 fatty acids. The proportions of eicosapentaenoic and docosahexaenoic acid were only 29-36% and 49-52% of those in controls, respectively. In vegans the ratio of n-3 to n-6 fatty acids was only about half that in omnivores. In addition to the lower levels of n-3 fatty acids, the proportions of palmitic and stearic acids were lower in serum cholesteryl esters, triglycerides and free fatty acids of vegans. The proportion of oleic acid was slightly lower only in serum cholesteryl esters and erythrocyte phosphatidylserine. The results show that, in the long term, the vegan diet has little effect on the proportions of oleic and arachidonic acids, whereas the levels of n-3 fatty acids are depressed to very low levels with prolonged consumption of the high linoleic and oleic acid components of this diet.     

Effect of diet on the rate of depletion of n-3 fatty acids in the retina of the guinea pig

This study has assessed the influence of maternal n-3 long chain polyunsaturated fatty acid supply and dietary manipulation after weaning on the retinal polyunsaturated fatty acid profile. Infant guinea pigs born of dams fed one of two commercial chow diets (differing in the amount of eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) were raised in two separate experiments, and subsequently partitioned into two diet groups, one supplied with a high level of alpha-linolenic acid (canola oil supplemented), the other with a very low level of alpha-linolenic acid (safflower oil supplemented). Guinea pigs born of dams supplied with the longer chain n-3 fatty acids in the commercial pellets (experiment 2) showed higher levels of retinal docosahexaenoic acid at weaning compared with those born to dams fed chow containing only alpha-linolenic acid (experiment 1). The rate of depletion of retinal docosahexaenoic acid after weaning onto the safflower oil diet was described by a two-stage exponential decay, possibly reflecting systemic and local conservation mechanisms, in conditions of dietary n-3 fatty acid deprivation. The rate of docosahexaenoic acid depletion in the group with the lower retinal docosahexaenoic acid at weaning was more than double the rate of depletion in the group with the higher weaning docosahexaenoic acid value. The endpoint retinal docosahexaenoic acid level at 16 weeks post-weaning after dietary n-3 fatty acid depletion on the safflower oil diet in the group, which started with the lower retinal docosahexaenoic acid level, was approximately half that compared with the group from the dams fed long chain n-3 fatty acids (experiment 1, 5% (interpolated), experiment 2, 9%). These results suggest that an adequately supplied mother is capable of providing an infant with enough n-3 fatty acids to withstand a longer period of dietary deprivation imposed after weaning.     

Polyunsaturated fatty acid metabolism in retinal and cerebral microvascular endothelial cells

Docosahexaenoic acid (22:6n-3), an n-3 essential fatty acid derived from elongation and desaturation of linolenic acid (18:3n-3), is found in abundant proportion in the brain and the retina. It is generally assumed that the liver is the major source of 22:6n-3 for these organs, although some retinal and cerebral cells, such as retinal pigment epithelium (Wang and Anderson, 1993. Biochemistry. 32:13703-13709) and brain astrocytes (Moore et al. 1991. J. Neurochem. 56:518-524) have the ability to produce 22:6n-3. The aim of the present study was to determine whether retinal and cerebral microvascular endothelium could synthesize 22:6n-3. After incubation of both cultured bovine retinal and rat cerebral endothelial cells with [3-14C] 22:5n-3 in presence of serum, radioactivity was primarily recovered in 20:5n-3, indicating active retroconversion reactions in both tissues. However, 22:6n-3, 24:5n-3, and 24:6n-3 were also labeled. All of these metabolites were released in the medium as free fatty acids. Retinal endothelial cells preferentially released labeled 24-carbon metabolites, whereas cerebral endothelial cells released relatively more 20:5n-3 and 22:6n-3. With heat-inactivated serum or no serum, both endothelial cell preparations showed relatively higher retroconversion levels. However, in serum-deprived cells, the elongation/desaturation pattern was affected in retinal cells only, with an accumulation of 24:5n-3 relative to a decrease of 24:6n-3 and 22:6n-3. Fatty acid composition analyses revealed a decrease in long-chain polyunsaturated n-6 and n-3 fatty acids in retinal cells maintained in inactivated serum compared to normal serum, while no change was found in cerebral cells. Taken together, these results suggest that 1) the synthesis of 22:6n-3 by both retinal and cerebral endothelial cells is independent of a delta4-desaturase; 2) retinal and cerebral endothelia could be a source of 22:6n-3 for the retina and the brain, respectively; and 3) retinal endothelial delta6-desaturase, which converts 24:5n-3 to 24:6n-3, could be stimulated by serum components.     

Influence of dietary fats upon systolic blood pressure in the rat

Studies were performed to determine whether feeding diets with differing fatty acid content and composition had an influence on systolic blood pressure in the rat. Weanling male rats were fed standard laboratory chow (2.9% fat in total), or synthetic diets (10% fat in total) containing fish oil, butter, coconut oil or corn oil, for 5 weeks. Coconut oil and butter diets were rich in saturated fatty acids, whilst fish oil and corn oil were rich in the n-3 and n-6 unsaturated fatty acids respectively. Systolic blood pressure was measured using an indirect tail-cuff method at the end of the feeding period, and compared to a group of weanling rats. Feeding the different diets did not alter the growth of the rats, so all animals were of similar weights at the time of blood pressure determination. Control (chow fed) animals, at nine weeks of age, had higher systolic blood pressures than the weanling, baseline control group. Fish oil fed rats had similar pressures to the chow fed rats. Corn oil fed rats had significantly lower systolic pressures than the controls. The rats led the diets rich in saturated fatty acids (butter and coconut oil) had significantly higher blood pressures than all other groups. Systolic blood pressure was found to be significantly related to the dietary intakes of saturated and unsaturated fatty acids. The dietary intake of linoleic acid was significantly higher in corn oil fed rats than in other groups. Systolic blood pressure was inversely related to linoleic acid intake. Feeding a diet rich in saturated fatty acids significantly increases blood pressure in the rat. A high intake of n-6 fatty acids, and in particular linoleic acid, appears to have a hypotensive effect. Prenatal exposure of the rats to a maternal low protein diet, abolished the hypertensive effects of the coconut oil diet and the hypotensive effect of the corn oil diet upon young adult females. The intrauterine environment may, therefore, be an important determinant of the effects of these fatty acids on blood pressure in later life.     

Effects of dietary fat saturation on eicosanoid production, platelet aggregation and blood pressure

The effects of dietary fat saturation on eicosanoid urinary excretion, platelet aggregation (PA) and blood pressure (BP) were studied in 42 healthy subjects. They consumed four consecutive diets differing in their fat saturation [saturated (SFA); monounsaturated (MUFA); polyunsaturated n-6 (PUFA n-6); and polyunsaturated n-6/n-3, (PUFA n-3)]. Each diet period lasted 5 weeks. There were no differences in 24-h 2,3-dinor-6- keto-prostaglandin F1 alpha excretion among dietary periods. A significant effect was noted regarding the excretion of 11-dehydro-thromboxane B2 (P < 0.0001). During the PUFA n-6 phase the excretion was significantly higher than during SFA and MUFA periods. Dietary fatty acid composition had a significant effect on ADP (1 mumolL-1) and collagen (2 mgL-1) induced PA. Dietary fat also had a significant effect on systolic and diastolic blood pressure (P < 0.0001). Both were significantly higher during the SFA period than during the other three periods. Our findings suggest that changes in dietary fatty acids may have mild, but significant, effects on eicosanoid production, platelet aggregation and blood pressure.     

Origins of neural crest cell diversity

The effect of diets containing 50% of fat calories from butter, butter enriched with mono- and polyunsaturated fatty acids, and margarines with and without trans fatty acids on the serum lipids of 38 healthy men in a free-living condition have been determined. Serum lipid responses to the high level of individual dietary fats were unexpectedly small. The butter diet produced a small, but significant rise (5%) in the total serum cholesterol and low density lipoprotein (LDL)-cholesterol, relative to all other diets. Enrichment of butter with either olive oil (50/50) or sunflower oil (50/50) failed to reduce serum lipid levels below habitual diet values. Hard margarine, containing 29% trans fatty acids, caused a decrease in apolipoprotein A-I and B levels, but did not change total serum cholesterol or LDL-cholesterol levels, relative to habitual diet values. A soft margarine, high in linoleate, with no trans fatty acids reduced total cholesterol, LDL-cholesterol, and apolipoprotein B significantly, relative to all diets. Soft margarine high density lipoprotein (HDL)-cholesterol levels remained unchanged, but apolipoprotein A-I values were decreased relative to habitual and butter diets. The quantities of saturated fatty acids and the sum of monounsaturated and polyunsaturated fatty acids consumed on the hard and soft margarines were equal; therefore, the different response of serum cholesterol and LDL-cholesterol between these two diets is attributable to the trans fatty acids in the hard margarine. The data indicate that trans fatty acids are not metabolically equivalent to the natural cis isomers and that they affect the serum lipid profile adversely.     

Simultaneous measurement of [18F]FDOPA metabolism and cerebral blood flow in newborn piglets

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.