Comparison of liver microsome enzyme and fatty acid composition recovery in adult and old rats deficient in 18:3n-3 refed a diet containing 18:3n-3

The effect of dietary n-3 deficiency on liver microsome enzymes activities and fatty acid composition was studied in adult (3 months old) and old rats (18 months old). At these two ages, deficient animals were refed with 18:3n-3 diet for 1 or 2 months and the recovery of these parameters was investigated. Cytochrome P 450 level was decreased by n-3 PUFA (Polyunsaturated fatty acid) deficiency. After refeeding, it returned to control values after 1 month. NADH-cytochrome b5 reductase activity was decreased, the activities of NADPH cytochrome c reductase, aminopyrine demethylase, aniline hydroxylase were also decreased, but in old rats they were increased by refeeding. N-3 PUFA deficiency caused a decrease of 18:2n-6 and 22:6n-3 and an increase in 20:4n-6, 22:5n-6 and 18:1n-9. After refeeding, in adult rats, the PUFA level remained lower; in old rats, the MUFA (Monounsaturated fatty acid) and PUFA levels returned to control values. Liver microsomal enzyme activities depend on the degree of unsaturation of fatty acids rather than the specific species of polyunsaturated fatty acids.

Effect of fish oil diet on fatty acid composition of phospholipids of brain membranes and on kinetic properties of Na+,K(+)-ATPase isoenzymes of weaned and adult rats

The influence of dietary (n-3) fatty acids (such as eicosapentaenoic and docosahexaenoic acids) as found in fish oil on Na+ sensitivity and ouabain affinity of Na+,K(+)-ATPase isoenzymes (alpha 1, alpha 2, alpha 3) was studied in whole brain membranes from weaned and adult rats fed diets for two generations. The long chain (n-3) fatty acids supplied by fish oil decreased the fatty acids of the (n-6) series compared with the standard diet, resulting in a decrease in the (n-6)/(n-3) molar ratio in both 21- and 60-day-old rats. On the basis of ouabain titration, three inhibitory processes with markedly different affinities were associated with isoenzymes, i.e., low affinity (alpha 1), high affinity (alpha 2), and very high affinity (alpha 3). It appears that the fish oil diet, in part via the modification of membrane fatty acid composition, altered the proportion and ouabain affinity of isoenzymes. Na+ sensitivity is the best criterion of physiologic change induced by fish oil diet. We calculated the Na+ activation for each isoenzyme and found one Na+ sensitivity and two Na+ sensitivities per isoenzyme in weanling and adult rats fed different diets, respectively. In contrast to alpha 2 and alpha 3, alpha 1 appears insensitive to membrane change induced by fish oil diet. Fish oil diet, which is known to confer cardioprotection, induced significant modulation of Na+,K(+)-ATPase isoenzymes at the brain level.

Alteration in membrane lipid order and composition in metabolically hyperactive fatty rat adipocytes

We have previously shown that adipose cells from young genetically obese Zucker rats are characterized by very high metabolic activity together with an increase in a wide range of membrane-mediated functions. The aim of the present study was to examine whether the physical properties of the membranes and the composition of the membrane lipids were altered in these cells. Plasma membranes and two intracellular membrane fractions were prepared by differential ultracentrifugation from inguinal adipose cells of 30-day-old obese (fa/fa) and lean (Fa/fa) littermates. The lipid order as measured by steady-state fluorescence polarization of diphenylhexatriene used as probe was markedly decreased in the plasma membranes of obese rat adipose cells. Consistent with this, the cholesterol-to-phospholipid ratio was significantly decreased, and the degree of unsaturation of the phospholipid fatty acids was significantly increased. In intracellular membranes, none of these parameters were altered by the different genotype. In fat cells from obese rats, both plasma and intracellular membranes exhibited a 2-fold decrease in the ratios of n-6/n-3 fatty acids mainly due to an enrichment in docosahexaenoic acid (22:6n-3). The data show that the fatty genotype is a determinant of membrane lipid order and composition in adipose cells. The alterations reported here for young obese Zucker rat adipocytes might be related to the metabolic hyperactivity of these cells.

Differential secretion of alpha 1-acid glycoprotein occurs in the Golgi complex of isolated rat hepatocytes. Evidence of partial retention in the Golgi

Using weakly basic amines, we investigated the step at which the secretion kinetics of concanavalin-A-retained and nonretained alpha 1-acid glycoprotein glycoforms diverge in isolated rat hepatocytes. Both chloroquine and primaquine, whose action on protein secretion is targeted to terminal domains of the Golgi apparatus, cancelled the kinetic difference without influencing carbohydrate chain sialylation. To test for a possible interaction of alpha 1-acid glycoprotein with Golgi membranes, we also permeabilized control and primaquine-treated hepatocytes, as well as purified Golgi preparations, with saponin. In each case, we found that alpha 1-acid glycoprotein was associated with Golgi membranes, the association being more marked in primaquine-treated cells than in control cells. Membrane-bound alpha 1-acid glycoprotein appeared to be preferentially retained on concanavalin A. Such retention could account for the divergent secretion kinetics of alpha 1-acid glycoprotein glycoforms.

[Magnetic resonance imaging of pulmonary coin lesion and bronchopulmonary cancer]

Magnetic resonance imagery (MRI) is less sensitive than computed tomography (CT) for the detection of pulmonary masses and cannot detect calcifications within such masses. MRI performed during the work-up for bronchial cancers has often been compared with CT scans: neither T nor N can be evaluated with more precision. Nevertheless, there are certain specific indications such as the exploration of proximal tumours with suspected extension into the mediastinum including cardiac and vascular invasion, tumours of the aorto-pulmonary window, the Pancoast-tobias syndromes, and tumours situated near the thoracic wall or the spine.

Effects of dietary fats on nucleoside triphosphatase activity and nuclear membrane fatty acid composition of rats during development

The effect of various dietary fats on the nucleoside triphosphatase (NTPase) activity and nuclear membrane lipid composition of rat liver during development was assessed. Rats fed a fat-free diet exhibited higher specific activity of NTPase at all ages, compared with control animals. In rats fed a sunflower oil diet, the specific activity of NTPase was also found to be highest at all ages than was observed in the control group. In contrast, animals fed the fish oil diet or peanut-rapeseed oil diet showed a decrease in NTPase activity in comparison with the control group. The specific activity of NTPase was correlated positively with dietary sigma PUFA n-6 (r = 0.03, p < 0.05) and negatively with the dietary sigma PUFA n-3 (r = -0.87; p < 0.05). The fatty acid composition of liver nuclear membranes of rats fed a fat-free diet revealed high levels of 16:1 n-9, 18:1 n-9, and 20:3 n-9 acids. A dramatic decrease in 18:2 n-6, 20:4 n-6, and 22:6 n-3 acids was observed. Animals fed a sunflower oil diet showed high levels of n-6 fatty acids, particularly 22:4 n-6 and 22:5 n-6, and low levels of monounsaturated fatty acids. However, when rats were fed a fish oil diet, the liver nuclear membranes were highly enriched in 20:5 n-3, and 22:6 n-3 acids, and there was a simultaneous decrease in arachidonic acid. From these observations it is concluded that dietary fats induce changes not only in the fatty acid composition of the nuclear membrane lipids but also in the specific activity of NTPase involved in nuclear function.

Deficiency of (n-6) but not (n-3) polyunsaturated fatty acids inhibits the secretagogue effect of prolactin in lactating rat mammary epithelial cells

The repercussions of various kinds of dietary polyunsaturated fatty acid (PUFA) deficiencies on the fatty acid composition of membranes and on the secretory activity of lactating female rat mammary epithelial cells were investigated. Primiparous female rats were fed different PUFA diets from weaning: adequate (n-6) and (n-3) PUFA supply; overall PUFA deficiency; specific (n-6) PUFA deficiency or specific (n-3) PUFA deficiency. Mammary gland phospholipids contained very low amount of (n-3) PUFA in control rats, and only 1% docosahexaenoic acid. The fatty acid composition of membrane phospholipids reflected the type of diet received by the animals, i.e., the diets deficient in the (n-3) or (n-6) PUFA series resulted in lower (n-3) or (n-6) PUFA, and the (n-3) + (n-6) deficient diet caused a true overall PUFA deficiency in the membranes. The morphology of cells from overall PUFA- or (n-6) PUFA-deficient rats showed an accumulation of secretory vesicles in the cytoplasm. Basal casein secretion was independent of the diet and of the composition of membrane phospholipids. However, prolactin did not have a secretagogue effect on cells from (n-6) PUFA- or overall PUFA-deficient rats but retained this effect on cells from (n-3)-deficient rats. These results emphasize the specific role of (n-6) PUFA in the functioning of the lactating mammary epithelial cell.

Polyunsaturated fatty acid composition of human milk in France: changes during the course of lactation and regional differences

Milk samples were collected 2-5, 15, 30, 60 and 90 days postpartum from 41 individual mothers recruited in three French cities in order to obtain a general view of the polyunsaturated fatty acid (PUFA) composition in France. Considering the overall results, linoleic acid (18:2 n-6) represented between 11.6% and 13% of total fatty acids in human milk. In contrast alpha-linolenic acid (18:3 n-3) accounted only for about 0.6%, and hence the 18:2 n-6 to 18:3 n-3 ratio was close to 20. Amounts of n-6 and n-3 long-chain PUFAs (LCPs) regularly decreased from postpartum days 2-5 (3.09%) to day 30 (1.67%), and then remained unchanged up to postpartum day 90; the n-6/n-3 LCP ratio ranged between 2.5 and 2. According to regional areas, there were significant differences (P < 0.05) only for colostrum contents of 18:3 n-3 and LCPs, the LCP ratio remaining unchanged. These data are discussed with regard to recent data on human milk fatty acid composition from Western countries and to the mechanisms involved in milk LCP balance.

Effect of an n-3 fatty acid-deficient diet on the adenosine-dependent melatonin release in cultured rat pineal

We studied the effect of a diet deficient in n-3 fatty acids on the adenosine-dependent melatonin release from cultured rat pineal gland after stimulation by 5'-N-ethylcarboxamidoadenosine (NECA), an A2 adenosine agonist. Experiments were conducted with 2-month-old rats raised on semipurified diets containing either peanut oil (n-3 deficients) or peanut plus rapeseed oil (controls). The proportion of docosahexaenoic acid (22:6 n-3) in the pineal total lipid fraction and in phosphatidylcholine and phosphatidylethanolamine was significantly decreased in n-3-deficient rats. This was compensated for partially by an increase in 22:4 n-6 and 22:5 n-6 levels. The activity of the cultured rat pineal, in terms of cyclic AMP content and N-acetylserotonin and melatonin release in the medium, was lower after stimulation by 10(-5) mol/L NECA in the group fed peanut oil than in the group fed peanut plus rapeseed oil. The increased ratio of n-6/n-3 fatty acids in pineal total lipids and the major glycerophospholipids (phosphatidylcholine and phosphatidylethanolamine) may have an important influence on the rat pineal responses. The results are discussed in the context of changes in membrane-bound proteins, including enzymes and/or receptors involved in the rat pineal gland function.

Prolactin transit through mammary epithelial cells and appearance in milk

In lactating mammary epithelial cells, prolactin (PRL) binds to its receptors, is endocytosed and carried to the milk. In order to study the transit of the hormone and its receptor respectively, the intracellular pathway of PRL and ot two monoclonal antibodies against PRL-receptor (PRL-R), labelled with biotin and colloidal gold, were monitored in incubated fragments of enzymatically dissociated mammary cells of lactating rabbits. PRL was internalised in endosomes and carried to microvesicular bodies, lysosomes, Golgi apparatus and secretory vesicles containing casein micelles. After 60 min of incubation at 37 degrees C, PRL was released in the incubation medium. M110 anti PRL-R was internalised in endosomes and detected mainly in microvesicular bodies during a one hour incubation. In contrast, A917 anti PRL-R also internalised in endosomes and in microvesicular bodies, was carried out to the Golgi apparatus and to the lumen of the acini after 5 min of incubation at 37 degrees C. These results suggest that an intracellular sorting occurs in the presence of the hormone or the different antibodies. The fatty acid composition of the mammary epithelial cell membranes influences the activity of these cells. To examine the effect of this membrane composition on the transit of PRL, the intracellular pathway of the hormone was studied in mammary cells of lactating rats previously fed with lipid deficient diets. Plasma levels of PRL were not modified in rats receiving a deficient diet compared to controls. Labelled PRL was accumulated inside the microvesicular bodies during a one-hour incubation at 37 degrees C. However, PRL was always detectable in milk, suggesting that the intracellular transit of PRL could be slowed down but not inhibited. Possible relationships between endocytosis of PRL and its secretagogue effect are discussed.

Oligosaccharide specificity of normal human hepatocyte alpha 1-3 fucosyltransferase

A purified alpha 1-3 fucosyltransferase (alpha 1-3 FT) was recovered in the Golgi fraction of isolated hepatocytes from normal human liver tissue. The efficiency of purification was controlled by measurement of fucose transfer to asialotransferrin (for alpha 1-3 FT), to phenyl-beta-D-galactose (for alpha 1-2 FT) and to 2' fucosyl lactose (for alpha 1-3/4 FT). The initial hepatocyte isolation step got rid of 97% and 94% of alpha 1-2 and alpha 1-3/4 total liver FT, respectively. After Golgi enrichment (26-fold purification and a yield of 7.6%), alpha 1-3 FT extract expressed a specific activity of 2 pM/min per mg protein. When incubated in optimized conditions with type 1, 2 or 6 oligosaccharide acceptors (10 mM), hepatocellular alpha 1-3 FT efficiently transferred fucose to N-acetyllactosamine and its 3' sialylated derivative, but poorly to lactose. When incubated with neutral or sialylated biantennary N-glycans, the enzyme expressed the highest affinity (Km = 0.38 mM) for the 3'bisialylated derivative. This suggests that hepatocellular alpha 1-3 FT is involved in the synthesis of sialosyl Le(x) determinants on cirrhotic alpha 1AGP.

Dietary alpha-linolenic acid at 1.3 g/kg maintains maximal docosahexaenoic acid concentration in brain, heart and liver of adult rats

We have previously determined the dietary alpha-linolenic requirement for membrane synthesis in the developing animal. This study measures the dietary requirement for maintaining normal membrane composition in adult rats, as determined by 22:6(n-3) (docosahexaenoic acid) concentration. Sixty-day-old rats, previously fed a diet containing both linoleic and alpha-linolenic acid, were divided into nine groups, each receiving different quantities of alpha-linolenic acid but the same amount of linoleic acid. They were killed 4 wk after initiation of the new diet to determine the minimum quantity of alpha-linolenic acid required in the diet for maintaining the 22:6(n-3) tissue concentration in brain (whole tissue, myelin and nerve endings), liver and heart. The minimal amount of dietary alpha-linolenic acid that maintained the maximal 22:6(n-3) level and minimal 22:5(n-6) level in tissues was considered to be the dietary requirement. The quantity was found to be 1.30 g/kg diet (0.26% of dietary energy). It was lower than that found for the developing animal (0.4% of energy). At lower quantities of dietary alpha-linolenic acid, 22:6(n-3) was replaced by 22:5(n-6) in the organs examined, except in nervous tissue, in which 22:6(n-3) was highly preserved.

Effect of age and alpha-linolenic acid deficiency on delta 6 desaturase activity and liver lipids in rats

The combined effects of age and of diet deficient in n-3 fatty acids on delta 6 desaturation of linoleic acid and on lipid fatty acid composition were studied in the liver of the rat at 2, 6, 12, 18 and 24 mon of age. The profiles of delta 6 desaturase activity and fatty acid composition were studied in the deficient rats refed, at these different ages, either with 18:3n-3 (mixture of peanut and rapeseed oils) or with 20:5n-3 + 22:6n-3 (fish oil) diets for 2, 4, 8 or 12 wk. Results showed that the liver delta 6 desaturation activity in the control rats remained high at 2 and 6 mon, decreased by 30% from 6 to 12 mon, and then remained stable from 12 to 24 mon. In the deficient rats, this activity remained high during the entire period studied. Thus, the profile of liver delta 6 desaturase activity after puberty was not related to age only; it also depended on the polyunsaturated fatty acid (PUFA) n-6 and n-3 balance in the diet. In the controls, in parallel with the delta 6 desaturase activity, PUFA metabolism could be divided into three periods: a "young" period, and "old age" period, separated by a period of transition between 6 and 12 mon. Recovery from PUFA n-3 deficiency occurred at all ages but in a different manner depending on whether the rats were "young" or "old". Recovery was faster if long-chain n-3 PUFA rather than alpha-linolenic acid were supplied in the diet.

Brain phospholipids as dietary source of (n-3) polyunsaturated fatty acids for nervous tissue in the rat

In a previous work, we calculated the dietary alpha-linolenic requirements (from vegetable oil triglycerides) for obtaining and maintaining a physiological level of (n-3) fatty acids in developing animal membranes as determined by the cervonic acid content [22:6(n-3), docosahexaenoic acid]. The aim of the present study was to measure the phospholipid requirement, as these compounds directly provide the very long polyunsaturated fatty acids found in membranes. Two weeks before mating, eight groups of female rats (previously fed peanut oil deficient in alpha-linolenic acid) were fed different semisynthetic diets containing 6% African peanut oil supplemented with different quantities of phospholipids obtained from bovine brain lipid extract, so as to add (n-3) polyunsaturated fatty acids to the diet. An additional group was fed peanut oil with rapeseed oil, and served as control. Pups were fed the same diet as their respective mothers, and were killed at weaning. Forebrain, sciatic nerve, retina, nerve endings, myelin, and liver were analyzed. We conclude that during the combined maternal and perinatal period, the (n-3) fatty acid requirement for adequate deposition of (n-3) polyunsaturated fatty acids in the nervous tissue (and in liver) of pups is lower if animals are fed (n-3) very long chain polyunsaturated fatty acids found in brain phospholipids [this study, approximately 60 mg of (n-3) fatty acids/100 g of diet, i.e., approximately 130 mg/1,000 kcal] rather than alpha-linolenic acid from vegetable oil triglycerides [200 mg of (n-3) fatty acids/100 g of diet, i.e., approximately 440 mg/1,000 kcal].

Age-related changes in delta 6 and delta 5 desaturase activities in rat liver microsomes

Age-related changes in delta 6 desaturation of [1-14C]alpha-linolenic acid and [1-14C]linoleic acid and in delta 5 desaturation of [2-14C]dihomo-gamma-linolenic acid were studied in liver microsomes from Wistar male rats at various ages ranging from 1.5 to 24 mon. Desaturase activities were expressed both as specific activity of liver microsomes and as the capacity of whole liver to desaturate by taking into account the total amount of liver microsomal protein. delta 6 Desaturation of alpha-linolenic acid increased from 1.5 to 3 mon and then decreased linearly up to 24 mon to reach the same desaturation capacity of liver measured at 1.5 mon. The capacity of liver to desaturate linoleic acid increased up to 6 mon and then remained constant, whereas microsomal specific activity was equal at 1.5 and 24 mon of age. The capacity of liver to convert dihomo-gamma-linolenic acid to arachidonic acid by delta 5 desaturation decreased markedly from 1.5 to 3 mon. It then increased to reach, at 24 mon, the same level as that observed at 1.5 mon. Age-related changes in the fatty acid composition of liver microsomal phospholipids at the seven time points studied and of erythrocyte lipids at 1.5 and 24 mon were consistent with the variations in desaturation capacity of liver. In particular, arachidonic acid content in old rats was slightly higher than in young rats whereas contents in linoleic and docosahexaenoic acids varied little throughout the life span.(ABSTRACT TRUNCATED AT 250 WORDS)

Impairment of consciousness induced by valproate treatment following neurosurgical operation

Eight patients, who underwent neurosurgery for various supratentorial lesions presented unexplained impairment of consciousness during the first post-operative days. These states ranged from stupor to deep coma, and two patients had an emergency re-exploration. All these patients were receiving the usual dosage (1000 to 1500 mg per day) of Valproic acid (VPA). The treatment had been initiated either several weeks or months previously in 4 cases, and was thus well tolerated, or the day before surgery in the 4 other cases. EEG recordings displayed diffuse abnormalities, delta waves and/or high voltage triphasic complexes, that led to the diagnosis of VPA intolerance and drug withdrawal. Then full clinical recovery and EEG clearing occurred within 1 to 5 days. VPA intolerances are wellknown but remain exceptional, about 1 case per 100.000. In our neurosurgical population, however, the rate was higher, approximately 2%. Wide areas of blood brain barrier destruction may contribute to the higher frequency of this easily reversible cause of post-operative stupor or coma.