Polyunsaturated fatty acids augment free radical generation in tumor cells in vitro

Polyunsaturated fatty acids (PUFAs) have been shown to inhibit both normal and tumor cell growth in vitro. As PUFAs are known to induce a respiratory burst and free radical generation in polymorphonuclear leukocytes and since free radicals are toxic to cells, we investigated the effect of PUFAs on a measure of free radical generation (nitroblue tetrazolium reduction) in normal human fibroblasts and breast cancer cells in vitro. Results suggested that linoleate (LA), gamma-linolenate (GLA), arachidonate (AA) and eicosapentaenoate (EPA) can enhance nitroblue tetrazolium reduction in tumor cells but not in normal cells. GLA, AA and EPA were 1 1/2 to 2 times more effective than LA in inducing free radical generation. This difference was not due to increased uptake of LA, AA and EPA by tumor cells. In fact, the uptake of LA was the same both in normal and tumor cells whereas that of AA and EPA occurred at approximately half the rate in the tumor cells compared to normal cells. This indicates that PUFA induced growth inhibition and cytotoxicity to tumor cells may, at least in part, be due to enhanced free radical generation.

A Mycoplasma genitalium protein resembling the Mycoplasma pneumoniae attachment protein

In previous studies with hyperimmune rabbit sera and monoclonal antibodies against the P1 protein of Mycoplasma pneumoniae, we obtained evidence of a shared antigenic determinant with a single protein of Mycoplasma genitalium. Because of biologic and morphologic similarities between these two human Mycoplasma species, attempts were made to characterize this cross-reacting protein of M. genitalium (designated MgPa). The protein was surface exposed and had an estimated molecular size of 140 kilodaltons. Electron microscopy with monoclonal antibodies produced against either MgPa or P1 demonstrated that MgPa is located over the surface of the terminal structure of M. genitalium which is covered by a nap layer. These immunologic and morphologic findings suggest that the MgPa protein of M. genitalium could be the counterpart of the P1 protein of M. pneumoniae.

Effect of dietary cholesterol on the release of prostacyclin from the mesenteric vascular bed in diabetic rat

Streptozotocin-induced diabetic female rats and age-matched control rats were fed a regular chow with or without the addition of 1% cholesterol in the diet. The release of 6-keto-PGF1 alpha, a prostacyclin metabolite, from the mesenteric vascular bed was significantly increased in diabetic rats. The production of PGI2 in diabetic rats was significantly reduced whereas that in the control was not affected by cholesterol feeding. The examination of the fatty acid composition of phospholipids from the mesenteric vascular bed indicated that proportions of stearic (18:0), linoleic (18:2n-6) and dihomo-gamma-linolenic (20:3n-6) acids were higher whereas those of oleic (18:1n-9) was lower in diabetic rats than those in the controls. Cholesterol feeding had no significant effect on the levels of arachidonic acid (20:4n-6) in the controls but it significantly decreased those in diabetic rats. It is suggested that cholesterol feeding lowers the release of PGI2 from the mesenteric vascular bed possibly because of a reduced level of arachidonic acid, the major precursor for prostaglandin synthesis. This could be due to an impairment of delta-5 desaturase.

Selective incorporation of n-3 and n-6 fatty acids in essential fatty acid deficient rats in response to short-term oil feeding

Essential fatty acid deficient male Sprague Dawley rats were fed for 7 days a fat-free semi-synthetic diet supplemented with 10% by weight of different oil supplements. The oil supplement was a mixture of olive, safflower and linseed oils prepared at different proportions so the dietary n-9/n-6/n-3 ratios were approximate 2/1/1, 1/2/1, 1/1/2, and 1/1/1. The fatty acid compositions of plasma and liver lipids were then examined. Our results show polyunsaturated n-6 and n-3 fatty acids were selectively incorporated into plasma and liver phospholipids, and also into plasma cholesteryl esters. A preferential incorporation of n-6 over n-3 fatty acids into plasma cholesteryl esters and phospholipids was also observed.

The influence of dietary marine oil (Polepa) and evening primrose oil (Efamol) on prostaglandin production by the rat mesenteric vasculature

The interactions of n-6 and n-3 fatty acids on prostaglandin metabolism in the isolated rat mesenteric vessels were studied. Sprague-Dawley rats (200-220 g) were fed for two weeks a fat-free semi-synthetic diet supplemented with 10% by weight of different combinations of Evening Primrose Oil (Efamol), a rich source of linoleic acid (LA) and gamma-linolenic acid (GLA), the immediate precursor of dihomo-gamma-linolenic acid (DGLA), and Polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% Efamol - 1% POL, 8% Efamol - 2% POL, 7% Efamol - 3% POL, 6% Efamol - 4% POL, 5% Efamol - 5% POL. The outflow of thromboxane (TxB2), prostacyclin (6-keto-PGF1 alpha), PGE2, and PGE1 was decreased in relation to the proportion of marine oil in the diet, except for the group which received 8% Efamol - 2% POL, and which showed an increase in 6-keto-PGF1 alpha, PGE2, and PGE1. The decrease in TxB2 was much greater than those of 6-keto-PGF1 alpha or PGE2, while PGE1 followed the same pattern as prostacyclin and PGE2. These results suggest that n-3 fatty acids, at high concentrations, inhibits conversion of both DGLA and AA to eicosanoids. Low concentrations of fish oil may, in contrast, increase formation of desirable 1 and 2 series eicosanoids.

Release of cholecystokinin and gallbladder contraction before and after gastrectomy

The contraction of the gallbladder by ultrasonography and release of cholecystokinin (CCK) by specific radioimmunoassay in response to the ingestion of oral fatty meal before and 1 month after gastrectomy in five patients with early gastric cancer was studied. Before gastrectomy, basal concentrations of CCK (13.4 +/- 2.3 pmol/L) rose significantly to a maximum of 23.3 +/- 3.6 pmol/L at 20 minutes after ingestion of oral fatty meal, and remained significantly elevated during the study. Gallbladder contraction began as CCK concentrations rose, demonstrating significant correlation with plasma CCK. One month after gastrectomy, CCK showed a rapid and greater response to the ingestion of fatty meal, attaining a maximum of 53.7 +/- 7.3 pmol/L at 10 minutes, then gradually falling to basal level. The maximal contraction of the gallbladder after gastrectomy was almost the same as before gastrectomy (62.7 +/- 4.0% of original area), showing a significant correlation with plasma CCK, but refilling of the gallbladder was induced earlier with corresponding reduction of plasma CCK. Simultaneous measurement of plasma concentrations of pancreatic polypeptide revealed a fairly similar response to plasma CCK before and after gastrectomy. The release of CCK is the chief mechanism by which the ingestion of a fatty meal causes contraction of the gallbladder even after gastrectomy as well as before gastrectomy.

Effect of dietary cholesterol and polyunsaturated fats on plasma and liver lipids in guinea pigs

Weanling male Hartley guinea pigs were fed for 6 weeks on a regular chow supplemented with 5% polyunsaturated fats (safflower, linseed, or evening primrose oil) or 5% saturated fats (hydrogenated coconut oil) with or without the addition of 1% cholesterol to the diet. Cholesterol feeding resulted in slower growth, hyperlipidemia, and a fatty liver. Cholesterol contents (predominantly in the form of cholesterol esters) in plasma and liver were increased, but the increase of plasma cholesterol was significantly reduced when unsaturated fats in place of saturated fat were added to the diet. The essential fatty acid contents in plasma and liver lipids were modulated by the dietary fats and by the cholesterol feeding. The latter reduced the proportions of 20:4 (n-6), but increased or had no effect on the levels of 18:2 (n-6). These results led to a reduced ratio of 20:4 (n-6)/18:2 (n-6), suggesting that cholesterol feeding may impair the desaturase activities.

Uptake and distribution of cis-unsaturated fatty acids and their effect on free radical generation in normal and tumor cells in vitro

We have previously shown that cis-unsaturated fatty acids (c-UFAs) possess a selective tumoricidal action that can be blocked by antioxidants. This property of c-UFAs might be due to various factors, including increased uptake, unusual distribution, or an ability to alter free radical generation in tumor but not normal cells. 14C-labelled linoleic acid (LA) uptake was almost the same in normal and tumor cells, whereas that of 14C-labelled arachidonic acid (AA) and 14C-labelled eicosapentaenoic acid (EPA) in tumor cells was substantially less than in normal cells. Tumor cells incorporate major portions of the fatty acids in the ether lipid and phospholipid fractions, whereas normal cells incorporate the fatty acids primarily in the phospholipid fraction. LA, AA, and EPA augmented nitroblue tetrazolium reduction, an indication of free radical generation, selectively in the tumor cells. These results suggest that there are significant differences between normal and tumor cells in fatty acid uptake and distribution, and in the ability of fatty acids to generate free radicals.

Protective effect of gamma-linolenic acid on aspirin-induced gastric hemorrhage in rats

The effects of feeding with gamma-linolenic acid (GLA) in comparison with linoleic acid on aspirin-induced gastric hemorrhage were studied in the rat. Gastric damage was examined macroscopically and histologically. Intragastric administration of 100 mg aspirin daily for 4 weeks produced hemorrhage in 3 of 8 rats receiving a linoleic-acid-enriched diet, but none in 8 rats receiving GLA-enriched diet. The levels of linoleic acid in plasma and liver phospholipids were significantly increased, whereas those of arachidonic acid (AA) were reduced in plasma and liver phospholipids of aspirin-treated animals fed linoleic acid. Similar, more pronounced changes occurred in those animals with hemorrhage. The reduced ratios of arachidonate/linoleate suggest that fatty acid desaturation in these animals was depressed. Treatment with GLA prevented these changes. Our results demonstrated that GLA could protect the gastric mucosa from aspirin-induced damage by bypassing the depressed delta-6-desaturation and thus providing a precursor for the synthesis of AA and prostaglandins.

Effect of removal of the cytolytic factor of Bacillus thuringiensis subsp. israelensis on mosquito toxicity

Solubilized crystal protein of Bacillus thuringiensis subsp. israelensis was fractionated by affinity chromatography using a monoclonal antibody directed against the crystal's 28 kDa peptide. The 28 kDa peptide was found to be relatively nontoxic to mosquito larvae although it does contain the hemolytic activity of the crystals. The crystal protein fraction depleted of the 28 kDa peptide was found to be nonhemolytic and to retain nearly full toxicity to mosquito larvae. These results suggest that the 28 kDa peptide is not required for the toxicity of solubilized crystal protein.

Dietary manipulation of ethanol preference in the Syrian golden hamster

Male Golden Syrian hamsters, in which ethanol preference was previously established, were fed a basal diet supplemented with essential fatty acid-rich oils (increased weekly from 10-160 g/kg diet), cholesterol (10 g/kg diet) or retinol palmitate (100 or 200 mg/kg diet), each in an independent study. Within 4-5 weeks, all three supplements were associated with significantly decreased ethanol preference. No consistent change in the fatty acid composition of liver or brain was associated with the decrease in ethanol preference but, in ethanol-fed hamsters, each of the supplements was associated with an increase in total cholesterol and the cholesterol/phospholipid ratio in liver. The essential fatty acid-induced reduction in ethanol preference was not associated with a significant change in blood ethanol elimination rate or time.

Changes of plasma lipids and long-chain n-3 and n-6 fatty acids in plasma, liver, heart and kidney phospholipids of rats fed variable levels of fish oil with or without cholesterol supplementation

Diets supplemented with 10% by weight of oil, either wholly safflower oil or proportinally (25, 50, 75 or 100%) replaced by fish oil, were given to 60 rats which had previously been deprived of dietary fat for 6 weeks. Half the animals on each dietary regimen were also given 1% of cholesterol. After 4 weeks of feeding, the plasma lipid contents and the phospholipid fatty acid compositions of plasma, liver, heart and kidney were determined. In general, the concentrations of plasma lipids were significantly reduced in animals fed a diet containing 5% or more of fish oil in comparison with those fed only safflower oil. Cholesterol feeding increased the levels of plasma cholesterol, whereas it lowered those of plasma triacylglycerols and phospholipids. The levels of 20:4(n - 6) in all four tissues were sharply reduced, whereas those of 18:2(n - 6) increased when 25% of dietary safflower oil was replaced by fish oil. Both 18:2(n - 6) and 20:4(n - 6) were decreased as the contents of dietary fish oil were further increased. The levels of long-chain n-3 fatty acids, e.g., 20:5(n - 3), 22:5(n - 3) and 22:6(n - 3) were increased as the intake of fish oil increased. The incorporation of 22:6(n - 3) was greater in plasma, liver and heart phospholipids, whereas that of 20:5(n - 3) was greater in kidney phospholipids. Cholesterol feeding also increased the levels of 18:2(n - 6) and 20:5(n - 3), whereas it decreased the levels of 20:4(n - 6) and 22:6(n - 3) in plasma and liver. However, these changes were not observed in heart and kidney.

Increased release of prostaglandins from the mesenteric vascular bed of diabetic animals: the effects of glucose and insulin

To study prostaglandin (PG) metabolism in peripheral vascular beds, PGs and TxB2 released from perfused mesenteric tissues were measured in both normal and streptozotocin (STZ)-induced diabetic rats. The release of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), thromboxane B2 (TxB2) and prostaglandin E2 (PGE2) was significantly increased in mesenteric vascular beds from diabetics in comparison with control rats. The 6-keto-PGF1 alpha/TxB2 ratio was decreased in diabetics. In order to clarify the mechanism of this imbalanced synthesis of eicosanoids, we infused buffer with 500 mg/dl glucose which was similar to the concentration of blood glucose in the diabetic rats. In response to this high glucose concentration, TxB2 released into the effluent from the mesenteric beds of normal animals was increased to the diabetic level. The release of the other PGs was not changed significantly. The 6-keto-PGF1 alpha/TxB2 ratio was decreased in control rats perfused with buffer containing 500 mg/dl glucose. We also investigated the effect of insulin (50 and 100 microU/ml) in the diabetic mesenteric vascular beds, but there were no changes in prostaglandin or TxB2 release. These data suggest that a high glucose level may have an important role in regulating TxA2 synthesis and in modulating the balance between PGI2 and TxA2 in diabetes. It is postulated that an increase in the micro-circulation of PGI2 may partially be protective against the progression of angiopathy.

The influence of dietary manipulation with n-3 and n-6 fatty acids on liver and plasma phospholipid fatty acids in rats

The interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague-Dawley rats (200-220 g) were fed a fat-free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose oil (EPO), a rich source of LA and gamma-linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% EPO-1% POL, 8% EPO-2% POL, 7% EPO-3% POL, 6% EPO-4% POL and 5% EPO-5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo-gamma-linolenic acid (DGLA) (p less than 0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid (AA) (p less than 0.01), a metabolite of DGLA through delta-5-desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA levels was found to exist (r = -0.765 in plasma and -0.792 in liver). However, there was no such relationship between AA/DGLA ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.

Effect of indomethacin treatment on prostaglandin excretion and tissue phospholipid fatty acid composition in rats bearing mammotropic pituitary tumor, MtT-F4

The hypothesis that hormonal changes induced by the mammotropic pituitary tumor, MtT-F4, might accelerate the conversion of n-6 fatty acids to prostaglandins, resulting in a partial depletion of n-6 fatty acids was examined. In tumor-bearing rats, the administration of indomethacin induced a 50% reduction of the urinary prostaglandin levels, but exerted no significant effect on the fatty acid composition of the tissue phospholipids. It is concluded that the observed depletion of n-6 fatty acids in tumor-bearing rats is not caused by an increased production of prostaglandins.

Demonstration of rectal varices by transhepatic inferior mesenteric venography

A case of rectal varices confirmed by percutaneous transhepatic inferior mesenteric venography is reported. By using the transhepatic approach, the mesenteric venous tributaries can be catheterized selectively with direct injection of the high-density dye, and the location and extent of varices are clearly demonstrated. Transhepatic inferior mesenteric venography can be used as an alternative method of angiographic investigation for rectal varices.

Triacylglycerol content of arachidonic acid varies inversely with total triacylglycerol in liver and plasma

In both liver and plasma from rats, hamsters, guinea pigs and monkeys, the correlation coefficients between percentage composition of arachidonic acid and the total triacylglycerol varied from -0.43 to -0.81 (P less than 0.01). No such relationship was present between percentage compositions of any of the essential fatty acids in phospholipids and total phospholipids.

Effect of different dietary proteins on plasma and liver fatty acid compositions in growing rats

Weanling male rats were fed semipurified diets containing 20% protein derived from casein, soy protein, or wheat gluten for 5 weeks. The fat source was 2% safflower oil (containing 79.4% 18:2n-6). In comparison with the casein-fed rats, the growth rate of rats fed plant proteins was slower, particularly that of rats fed the wheat gluten diet. The plasma cholesterol levels were significantly lower in rats fed wheat gluten than in those fed the other dietary protein regimens. The fatty acid compositions of plasma and liver lipids were also examined. The ratios of 16:1/16:0, 18:1/18:0 and 20:4n-6/18:2n-6 in both plasma and liver phospholipids and cholesteryl esters were consistently reduced in animals fed plant protein suggesting a reduced activity of fatty acid desaturation. The reduction of fatty acid desaturation may possibly be attributed to the low lysine/arginine ratio in plant proteins.

The effects of maternal murine cytomegalovirus infection on the mouse conceptus at different gestational stages

The effects of murine cytomegalovirus (MCMV) on the prenatal development of the CD-1 mouse were investigated. Two sets of experiments were performed. In the first, mice were inoculated with different doses of MCMV on gestational day 7, and in the second, pregnant animals were inoculated with a subacute injection dose at different gestational stages. The effects of maternal infection on pregnancy in terms of maternal sickness, embryo lethality, date of parturition, litter size, postnatal death, and pups' body weight on d 1 and d 3 postpartum were investigated. High-dose MCMV infection on d 7 of pregnancy resulted in a significant increase in early embryo resorption and also in a reduction of the neonatal body weight of surviving pups. Two gestational stages were identified as being especially susceptible to MCMV infection. Most embryonic death as indicated by resorption rates was found after treatment on d 9, whereas perinatal death was most frequent when treatment was done on d 13 of gestation. Still births and neonatal death within 24 h of birth were found commonly in this latter group, which also showed the most pronounced growth retardation. The phenomenon of delay in time of parturition was noted and found to be most significant in groups of animals that were inoculated on d 3 or d 13. This investigation suggests that the effects of MCMV on the CD-1 mouse vary greatly with the age of the embryo and the course of the infection.

Influence of different dietary fatty acid sources on erythrocyte lipids and plasma and liver essential fatty acids in hamsters fed ethanol

Hamsters fed ethanol were given three different dietary sources of essential fatty acids; safflower oil, evening primrose oil (both mainly n-6 fatty acids) or linseed oil (mainly n-3 fatty acids). After 7 weeks, plasma, erythrocyte and liver lipids and fatty acids were analyzed. Plasma and liver lipids were not significantly different in the ethanol-fed hamsters compared to the controls. Erythrocyte total phospholipid was increased only in the ethanol-fed groups given n-6 but not n-3 fatty acids. Some fatty acid changes induced by ethanol were predictable, e.g. lower 20:4 n-6 in hamsters fed n-6 fatty acids, but others were not predictable, e.g. higher 22:6 n-3 in all the ethanol-fed groups. The effect of ethanol on hamster lipids and fatty acid composition appears dependent on the predominant class of dietary fatty acids.

Effects of dietary saturated, N-6 and N-3 polyunsaturated fats on blood pressure and prostaglandins outflow from perfused mesenteric vascular bed in rats

Effects of the dietary administration of saturated fat and of n-6 and n-3 polyunsaturates on blood pressure, prostaglandin metabolism in small vessels, tissue fatty acid distribution and urinary PGE2 excretion were compared. Rats were divided into three groups. Diets contained 10% hydrogenated coconut oil (HCO), 10% safflower oil (SFO) or 10% cod liver oil (CLO) added to a basic fat free diet for 10 weeks. Systolic blood pressure was increased in the CLO group animals. Urinary PGE2 excretion was decreased in the HCO and CLO groups as compared to that in the SFO group animals. PGE2, 6-keto-PGF1 alpha and thromboxane (Tx) B2 outflow from isolated perfused mesenteric arterial beds were extremely decreased in the CLO group animals, and to a lesser extent in the HCO group as compared to the SFO animals. In the tissue phospholipid, 20:3n-9/20:4n-6 ratios were increased in the HCO group indicating essential fatty acid deficiency, and n-6 and n-3 polyunsaturates were elevated in the SFO and the CLO group animals respectively. Arachidonic acid concentration was highest in the SFO group, while there was no significant differences between the HCO and the CLO group. These results suggest that dietary fatty acid manipulation affects urinary PGE2 excretion and PGI2, PGE2 and TxA2 synthesis in mesenteric arterial beds and also changes the tissue fatty acid distribution. Furthermore, n-3 polyunsaturates caused an extreme reduction of 2-series PGs synthesis in small resistance vessels.

Prospective studies on nasopharyngeal carcinoma in Epstein-Barr virus IgA/VCA antibody-positive persons in Wuzhou City, China

A serological mass survey was carried out in Wuzhou City in 1980, 1,136 IgA/VCA-positive persons being followed up for 4 years. Altogether 35 NPC cases were detected, of which 15 (43%) were in stage I and 17 (48.5%) in stage II, early cases (I + II) thus amounting to 91.5%. The detection rate of early cases was 2.9 times higher than in our outpatient clinic. IgA/VCA antibody could be detected 16-41 months prior to clinical diagnosis of NPC. We conclude that, if IgA/VCA-positive individuals are examined routinely once a year, NPC can be detected in the early stages of evolution. The annual detection rate of NPC in IgA/VCA antibody-positive individuals was 31.7 times higher than that of the annual incidence of NPC in the general population in the same age group, while during the 4-year follow-up period the incidence was 7.5 times higher than in the general population for the same age group. These results further indicate that EB virus plays an important role in the development of NPC, and that serological screening and follow-up studies are valuable for the early detection of NPC.

Short-term effect of dietary cholesterol on tissue n-6 fatty acids in fat-deficient rats

Weanling female rats raised on a fat-free diet for 8 weeks were then given the same diet supplemented with 0, 0.25, 0.5, or 1% by weight of cholesterol in addition to 10% of safflower oil for 3 days. Fatty acid compositions of cholesteryl esters (CE), triglycerides (TG), and phospholipids (PL) in liver and plasma were examined. Cholesterol feeding increased plasma and liver cholesterol contents and also affected the patterns of n-6 polyunsaturated fatty acids. There were no consistent changes in either plasma and liver TG which contained little 20:3n-6 and 20:4n-6. The levels of 20:3n-6 increased in plasma and liver PL, while proportions of 20:4n-6 decreased in liver and plasma CE. However, the absolute amount of 20:4n-6 in cholesteryl esters increased because of a threefold rise in cholesteryl ester levels. The changes might be attributable to an increased utilization of 20:4n-6 for cholesterol transport and/or an inhibition of delta 5-desaturation of n-6 fatty acids by cholesterol feeding.

Effect of dietary alpha- and gamma-linolenic acid on tissue fatty acids in guinea pigs

Guinea pigs were fed regular chow diets supplemented with 5% (by weight) safflower oil, evening primrose oil, or linseed oil for 6 weeks. The unsaturated fatty acid content of these oils was 78.9% of 18:2n6, 74.1% of 18:2n6, and 9.2% of 18:3n6, or 21.5% of 18:2n6 and 46.9% of 18:3n3, respectively. In comparison with 18:2n6, dietary supplementation with 18:3n6 significantly increased the tissue levels of 18:3n6 and 20:3n6, whereas dietary 18:3n3 significantly elevated the levels of 18:3n3 in plasma and liver lipids. Dietary 18:3n3 also significantly increased 22:5n3 and 22:6n3 in total phospholipids. The tissue levels of 20:4n6, on the other hand, were not affected by either treatment. These data suggest that both delta 6- and delta 5 desaturation of n-6 fatty acids in guinea pigs are low, and that the metabolism of n-3 and n-6 fatty acids may be regulated by two different enzyme systems.

Plasma essential fatty acids in pure and mixed race American Indians on and off a diet exceptionally rich in salmon

Eskimos on a traditional diet have unusually low prevalences of cardiovascular disease and cancer. One possible reason is the high intake of eicosapentaenoic acid (EPA) which is thought to account for the high EPA and low arachidonic acid (AA) levels in Eskimo plasma. People who also consume a traditional diet exceptionally rich in EPA are the Indians of the west coast of Vancouver Island. There are about 12,000 of these people and their traditional diet has been affected much less than that of the Eskimos. When on their traditional diet the Vancouver Island Indians, like the Eskimos, have high EPA and low AA levels in plasma. When eating European food, EPA levels are in the European range, but AA levels are still exceptionally low, a finding also reported from Eskimos living in Denmark. In a small mixed race group, AA levels were intermediate between those in pure Indians and in Europeans. The high EPA levels in Eskimos and West Coast Indians are related to diet. The low AA levels, in contrast, are probably genetically determined. Unusual disease patterns in these populations cannot be entirely attributed to diet.

Plasma cholesteryl sulfate in Friedreich's ataxia

Alteration of membrane fluidity and anomalies of membrane structural proteins have been suspected in Friedreich's ataxia. Plasma lecithin:cholesterol acyltransferase (LCAT) activity is also lowered in this disease, presumably because of a substrate effect. The membrane-stabilizing effect of cholesteryl sulfate (CS) and its inhibitory effect on LCAT activity prompted us to measure this substance in the plasma of Friedreich's ataxia patients as well as in normal subjects and in patients with Charlevoix-Saguenay disease. Plasma cholesteryl sulfate concentrations were significantly higher in Friedreich's ataxia, with levels above the upper limit of normal in nearly half of the cases. This increase was unrelated to age, sex or plasma cholesterol levels, but closely associated with the severity of the disease and thus considered to be secondary. A similar phenomenon (except the association with severity) was observed in Charlevoix-Saguenay ataxia. Levels also tended to be higher in first-degree relatives of Friedreich cases. The significance of these findings is discussed in the light of recent knowledge and experimental data obtained in this laboratory on rats made deficient in essential fatty acids. The highest concentrations of CS observed in Friedreich's ataxia (1097 micrograms/dL, 6 times the normal mean) was only 25% as high as the concentrations reported to inhibit LCAT activity.

Essential fatty acids in plasma, red blood cells and liver phospholipids in common laboratory animals as compared to humans

Essential fatty acids were estimated in plasma, red blood cells and liver total phospholipids in rats, mice, hamsters, guinea pigs, rabbits and humans. There were large species differences, suggesting that different species levels should be borne in mind when choosing an animal for a particular study. The 2 species most susceptible to atheroma, the guinea pig and the rabbit, had very high levels of linoleic acid and low levels of linoleic acid metabolites. n-3 fatty acid levels were low in guinea pigs and rabbits and the ratio of n-3 to n-6 fatty acids also was low in the rat. Mice and hamsters had the highest n-3 levels, suggesting they may be the best species to use for studies on the roles of n-3 essential fatty acids. Mice and hamsters and, in some respect rats, were closest to humans in their fatty acid patterns.

The lipid content of the diabetic kidney of the rat

Rats were made diabetic by intravenous administration of streptozotocin, 100 mg/kg. Six groups of animals were studied: normal; animals given a supplement of 100% corn oil margarine; insulin-treated normoglycemic diabetic; hyperglycemic nonacidotic diabetic; ketoacidotic diabetic; and NH4Cl acidotic. The kidneys were removed from anesthetized animals. The renal cortex was separated from the medulla, freeze-clamped, and homogenized. Total lipids were extracted and measured gravimetrically. Lipid fractions were determined by thin-layer chromatography. Fatty acids of triacylglycerols and of phospholipids were analyzed by gas chromatography. Plasma triacylglycerols were elevated in hyperglycemic nonacidotic rats and more so in ketoacidotic animals. Total kidney lipids were 18% higher in nonacidotic hyperglycemic rats and 56% higher in ketoacidotic diabetic rats. This was due to accumulation of triacylglycerols while the phospholipid and cholesterol fractions did not change. Examination of long-chain fatty acids of kidney cortex triacylglycerols revealed that palmitate rose in a significant fashion while linoleate fell. This pattern was similar in all three groups of diabetic animals. The present data characterize the lipid content of the experimental rat diabetic kidney. They establish that the accumulation of lipids in the renal cortex during diabetes is related to triacyclgycerols and their palmitate content. Our study also provides a clear profile of plasma triacylglycerols during diabetes mellitus in the rat.

The effects of dietary cholesterol on blood and liver polyunsaturated fatty acids and on plasma cholesterol in rats fed various types of fatty acid diet

Male rats were fed on a fat-free diet for 8 weeks and then switched to diets containing 10% hydrogenated coconut oil (HCO), safflower oil (SFO) or evening primrose oil (EPO). Half of each group was also given 1% of cholesterol in the diet. After 5 further weeks, plasma, red cell and liver fatty acids were measured in the various lipid fractions. Plasma and liver cholesterol also were estimated. In almost all fractions and on all three diets, feeding cholesterol led to accumulation of the substrates of desaturation reactions and to deficits of the products of these reactions. The results were consistent with inhibition of delta-6, delta-5 and delta-4 desaturation of n-6 essential fatty acids. Since the diets were deficient in n-3 fatty acids, levels were very low but were also consistent with inhibition of desaturation. In contrast, cholesterol had relatively less consistent effects on 20:3n-9, suggesting that desaturation of n-9 fatty acids was less inhibited. Plasma cholesterol levels rose sharply in the HCO and SFO groups but not at all in the EPO group. EPO contains the product of delta-6-desaturation, 18:3n-6, suggesting that conversion of linoleic acid to 18:3n-6 and possibly to further metabolites may be important for the cholesterol-lowering effect of polyunsaturates.

Effect of dietary depletion and repletion of linoleic acid on renal fatty acid composition and urinary prostaglandin excretion

To study the effect of dietary modification on urinary prostaglandin E (UPGE) excretion and on renal fatty acid compositions, weanling male rats were raised on a fat-free diet for 6 weeks and were switched to a diet containing 2 energy % of linoleic acid (LA) for 8 days. During fat deprivation, UPGE excretion increased in the first week (6.9 ng/24 hours urine), fell to a minimum of 1.1 ng/24 hours at 3rd week and thereafter remained at a level lower than that in the controls (3.1 ng/24 hours). UPGE excretion returned rapidly to normal (2.7 ng/hr) only 24 hours after LA supplementation. During LA treatment, arachidonic acid (AA) concentrations in renal cholesteryl esters rapidly increased from 19% to 27% (33% in the controls), while concentrations in renal phospholipids (PL) and renal free fatty acids (FFA) did not change during the first four days but reached the normal range at the 8th day. The present studies demonstrate that chronically fat deficient animals excreted significantly less UPGE than that in the controls. However, this deficiency could be rapidly reversed by LA supplementation despite the fact that AA levels in renal lipid fractions remained well below normal. This suggests that dietary LA may be rapidly converted to AA and subsequently to PGE without AA levels rising in the lipid fractions usually thought of as being PG precursors.

Prostaglandin precursors in plasma phospholipids of patients with psoriasis: effects of treatment with coal tar

Plasma phospholipids of patients with psoriasis have significantly reduced levels of dihomogammalinolenic acid (20:3n-6), arachidonic acid (20:4n-6) and adrenic acid (22:4n-6), the precursors of the 1, 2 and homo-2 series of prostaglandins (PGs). Concentrations of the 3 series PG precursor, eicosapentaenoic acid (20:5n-3) were normal. Hospital treatment with a coal tar regime produced a rise in 20:3n-6 to levels which were significantly above normal.

Tissue phospholipid fatty acid composition in the diabetic rat

Tissue phospholipid fatty acid compositions in streptozotocin-induced diabetic rats were studied. The major changes in liver, plasma, erythrocyte and heart were increased proportions of linoleic and dihomo-gamma-linolenic acids and a decreased proportion of arachidonic acid. The latter was not significantly changed in phospholipids of kidney, adrenal gland and testis. Skin fatty acids in diabetic rats showed an increase in the proportion of arachidonic acid and a reduction in the proportion of linoleic acid. The fatty acid desaturating activity in diabetes may be regulated differently in different tissues.

Fatty acids in plasma and red cell membranes in normal humans

A detailed study was made of the fatty acid composition of plasma triglycerides, free fatty acids, phospholipids, red cell total phospholipids, phosphatidylcholine and phosphatidylethanolamine in 32 normal males and 18 normal females. No sex differences could be detected. There were substantial differences in the compositions of the various fractions and long-chain polyunsaturated fatty acids were particularly important in the red cells.

Humoral antibody response to individual viral proteins after murine cytomegalovirus infection

The purpose of this study was to identify viral proteins that played an important role in the humoral immune response to murine cytomegalovirus (MCMV). Viral proteins were separated from a purified virus preparation on polyacrylamide gels, were blotted onto nitrocellulose strips, and were reacted with antisera collected from mice on various days post infection. No antibody response was detected in serum obtained 5 days post infection, but by 10 days there was a faint response to five different proteins. Thereafter, the number of proteins eliciting an antibody response, as well as the intensity of the response, increased with time so that by 42 days post infection a response to 13 major antigens was detected. This method provides a means of separating out important immunogens from the more than 30 different MCMV proteins originally identified by polyacrylamide gel electrophoresis. Such information may improve our understanding of the pathogenesis of MCMV infection as well as host immune responses to the virus.

Humoral antibody response to individual viral proteins after murine cytomegalovirus infection

The purpose of this study was to identify viral proteins that played an important role in the humoral immune response to murine cytomegalovirus (MCMV). Viral proteins were separated from a purified virus preparation on polyacrylamide gels, were blotted onto nitrocellulose strips, and were reacted with antisera collected from mice on various days post infection. No antibody response was detected in serum obtained 5 days post infection, but by 10 days there was a faint response to five different proteins. Thereafter, the number of proteins eliciting an antibody response, as well as the intensity of the response, increased with time so that by 42 days post infection a response to 13 major antigens was detected. This method provides a means of separating out important immunogens from the more than 30 different MCMV proteins originally identified by polyacrylamide gel electrophoresis. Such information may improve our understanding of the pathogenesis of MCMV infection as well as host immune responses to the virus.

Fatty acid composition of tissue phospholipids and prostaglandin excretion in hyperlipidemia induced in rats by implantation of the mammotropic pituitary tumor MtT-F4

A mammotropic pituitary tumor, MtT-F4, was implanted into male Fisher 344 rats for a period of 4 weeks. This tumor induced growth retardation, hyperlipidemia, hepatic hypertrophy and adrenal hyperplasia. Lipids were extracted from various tissues. In tumor-bearing rats, phospholipid concentration was found to be increased in plasma, spleen and testis. Distribution among the various phospholipid classes was similar to that of controls except in liver and heart, where phosphatidylcholine was increased at the expense of phosphatidylinositol and phosphatidylserine. The main difference was in the fatty acid composition of major phospholipids. The proportion of omega 6 fatty acids was lower and that of docosahexaenoic acid of the omega 3 series (22:6 omega 3) was higher in most tissues, especially in plasma, liver, heart and kidney. Concurrently, the urinary excretion of two endogenous metabolites of PGI2 (2,3-dinor-6-keto-PGF1 alpha and 6,15-diketo-13,14-dihydro-2,3-dinor-PGF1 alpha) was found to be increased significantly in tumor-bearing rats. The results raise the hypothesis that hormonal changes induced by the MtT-F4 tumor accelerate the conversion of arachidonic acid (20:4 omega 6) to prostaglandins. This effect, perhaps coupled with a diversion of linoleic acid (18:2 omega 6) towards other metabolic processes, would account for a partial depletion of membrane phospholipids in 18:2 omega 6 and for the reduced production of longer chain omega 6 unsaturated acids from 20:4 omega 6, creating a state of "relative essential fatty acid deficiency." As a result, the metabolism of omega 3 fatty acids is altered towards an enhanced production of 22:6 omega 3 which accumulates in the lipids of cell membranes to compensate for the depletion of unsaturated acids of the omega 6 series.

Identification of human sperm antigens to antisperm antibodies

We have successfully applied SDS (sodium dodecyl sulfate) gel/protein blot radioimmunobinding method to identify the molecular size of sperm antigens that elicit antisperm antibodies from patients with unexplained infertility. Following the transfer of renatured proteins from SDS gel of human sperm extract onto nitrocellulose strips, the radioimmunobinding was performed by incubating the strips with patients' sera at 1:100 dilution and then with I125-labeled goat antihuman immunoglobulin G (IgG) or protein A as detecting probes. Unique sperm antigens that reacted with some patients' sera were identified following the autoradiography of the incubated paper strips. Among the fifty-nine standard serum samples from the Reference Bank of the World Health Organization, about one-fourth of them were found to react predominantly with a sperm protein band having the reference value (Rf value) of 0.2 and the approximate molecular weight of 90,000 dalton. A similar analysis was also performed with serum samples from vasectomized patients. Some of them also revealed a specific binding with the sperm antigen(s) of similar molecular weight. The results of this analysis were also compared with those of conventional tests for sperm antibodies as well as those of microplate radioimmunoassays and enzyme-linked immunoassays. This study suggests that SDS gel/protein blot radioimmunobinding method can be a useful tool for the molecular identification of unique human sperm antigen(s) that elicit naturally occurring antisperm antibodies in patients with unexplained infertility.

Schizophrenia: the role of abnormal essential fatty acid and prostaglandin metabolism

There are two series of essential fatty acids (EFAs), the n6 series starting with linoleic acid and the n3 series starting with alpha-linolenic acid. Members of both series are important in brain structure and can act as precursors for prostaglandin formation. Normally the desaturase enzymes which metabolize EFAs have a higher affinity for the n3 series. It is proposed that in schizophrenia mutant desaturases are present which prefer the n6 series. This change would account for the low levels of linoleic acid, dihomogammalinolenic acid and 1 series prostaglandins which have been reported in schizophrenia. It would also explain the high levels of arachidonic and alpha-linolenic acids and the recently described therapeutic response to alpha-linolenic acid. The abnormal pattern in n6 series EFAs in schizophrenics can almost exactly be imitated in rats by depriving them of n3 EFAs. This is the nearest experimental equivalent to an inability to metabolize EFAs because of an enzyme defect. Heterozygotes carrying such a mutant gene would have an advantage over either form of homozygote since they would be better able to cope with variations in dietary intake of n3 and n6 EFAs.

Effect of methyl linoleate administration on phospholipid fatty acid composition and osmotic fragility of erythrocytes in essential fatty acid deficient rats

Methyl linoleate (18:2 omega 6) was administered to rats deficient in essential fatty acids (EFA) and the effects on osmotic fragility and lipid composition of their red blood cells were studied. Even if they remained deficient in omega-3 fatty acids, the fragile red cells of EFA-deficient rats were remarkably strengthened by the linoleate treatment. It is concluded that omega-3 fatty acids are not essential for the maintenance of cell membrane integrity in rats. Since the cholesterol/phospholipid ratio in red cells was lower in untreated than in treated rats, it is suggested that this factor might be responsible in part for the higher fragility of red cells in EFA-deficient rats. Despite the prolonged administration of overload quantities of methyl linoleate, the proportion of 18:2 omega 6 in the red blood cell phospholipids of treated rats was actually lower than that in rats fed a regular stock diet, while the relative content of other omega-6 fatty acids (20:4 omega 6, 22:4 omega 6, and 22:5 omega 6) increased. These results indicate that the metabolic processes of omega-6 fatty acids in treated rats were stimulated, probably as a result of the lack of competition from omega-3 fatty acids for the same enzyme systems.

Structural and functional aspects of cultured epididymal epithelial cells isolated from pubertal rats

Acidic epididymal glycoprotein (AEG) and androgen-binding protein (ABP) antisera were used to study functional activities of primary cell cultures of the epididymal epithelium of 20--23-day-old rats. Extensive AEG immunoreactivity was associated with almost all epithelial cells of the distal caput, corpus and cauda epididymidis. ABP immunoreactivity was solely confined to some epithelial cells of the caput epididymidis. AEG and ABP immunoreactive cells were identified as principal cells. Morphological studies of enzymically dispersed aggregates of the epididymal epithelial cells showed that stromal cells were satisfactorily removed and that cell aggregates consisted of a predominant population for cells displaying the morphological characteristics of principal cells. Scanning and transmission electron microscopic studies of cultured epididymal epithelial cells in monolayers demonstrated that microvilli and pit-like invaginations of the cell surface were preserved during the first 7--10 days of culture and then gradually disappeared. Other characteristic subcellular structures such as Golgi apparatus and rough endoplasmic reticulum cisterna were preserved. Electrophoretic analysis of [35S]methionine-labelled secretory polypeptides released by epididymal epithelial cells into the culture medium demonstrated a distinct protein band pattern which differed from that observed in the medium of cultured rat Sertoli cells. These results demonstrate that primary cultures of epididymal epithelial cells isolated from sexually immature rats maintain several differentiated characteristics of the intact organ and therefore provide a valuable system for the study of epididymal epithelial cell function.

Monoclonal antibodies to human sperm antigens

To elucidate the molecular nature of human sperm autoantigens, attempts were made to raise monoclonal antibodies against these antigens, by hybridoma techniques. After successive immunizations with the particulate fractions of human sperm extract in BALB/c mice, the spleen cells were fused with P3-X63-Ag8 myeloma cells. Several clones and their subclones were obtained and shown by microplate radioimmunoassay to produce antibodies against human sperm antigens. When SDS gel/protein blot radioimmunobinding was used for further molecular analysis, three independently derived clones were shown to produce antibodies, all of which cross-reacted with the same two human sperm antigens with a molecular weight of about 10,000. Using an indirect immunofluorescence assay, antibodies produced by these clones were shown to react with antigens localized on the acrosomal regions of human spermatozoa. Monoclonal antibodies produced by other clones, however, showed no cross-reactivity with any of the blotted proteins from SDS gels of human spermatozoa. Some possible reasons for this are presented.