Different kinetic in incorporation and depletion of n-3 fatty acids in erythrocytes and leukocytes of mice.

n-3 PUFA are well known for their anti-inflammatory effects. However, there has been only limited study on the kinetics of incorporation and depletion of n-3 PUFA in immune cells. In the present study we investigated the incorporation and depletion of n-3 PUFA in erythrocytes and leukocytes in mice during a 6-wk feeding period. Over the first 3-wk period (the incorporation period) the mice were fed a special diet with a high n-3/n-6 PUFA ratio. In the following 3-wk period (the depletion period) the mice were fed a standard chow diet. A linear increase of the concentration of EPA and DHA in erythrocyte membranes was observed during the incorporation period, whereas a stagnation was observed after the second week for leukocytes. The level of EPA did not fall to the background level after the depletion period, and the level of DHA was kept almost constant during the depletion period in the erythrocyte membranes. In leukocytes the concentration of both EPA and DHA decreased during the depletion period, but did not reach the background level after the 3-wk depletion. In conclusion, the kinetics of EPA and DHA in the different cells are different. The rate of incorporation is faster than that of depletion for n-3 PUFA. More n-3 PUFA can be incorporated into leukocytes in comparison with erythrocytes. The ratio of n-3/n-6 PUFA is more important than the amount of n-3 FA in changing the FA compositions of membrane lipids.

Dietary structured lipids for post-weaning piglets: fat digestibility, nitrogen retention and fatty acid profiles of tissues.

In four groups of post-weaning piglets the effects of triacylglycerol structure and fatty acid profiles of four dietary fats on apparent faecal nutrient digestibility, nitrogen retention and fatty acid profiles of platelet and erythrocyte membranes, liver, adipose tissue and skeletal muscle were examined. Dietary fats included as 10% (w/w) of the diets were two structured fats of rapeseed oil interesterified with tridecanoin (R1) or coconut oil (R2), respectively, one mixture of rapeseed oil and coconut oil (R3) and rapeseed oil as control (R4). Faeces and urine from piglets weaned at 28 days of age were collected quantitatively during three periods each of 5 days, in which the piglets were kept in metabolism cages for measurement of apparent faecal nutrient and energy digestibility and nitrogen retention. Apparent faecal fat digestibilities were significantly improved in groups fed interesterified fats or the physical mixtures (R1, R2 and R3) compared with rapeseed oil (R4). Apparent faecal nitrogen digestibility and retention were similar in all four groups in the three periods, but increased with time. Apparent faecal fat digestibilities were significantly improved from the first to the third week in the groups R1 and R2. Fatty acid profiles in platelet and erythrocyte membranes and in tissues reflected the fatty acid profile of the dietary fat, except for medium-chain fatty acids, which were only found in low proportions, indicating that 10:0 was mainly used as an energy source.

Lymphatic transport of fat in rats with normal- and malabsorption following intake of fats made from fish oil and decanoic acid. Effects of triacylglycerol structure.

Fish oils contain essential polyunsaturated fatty acids of the n-3 family. In fat malabsorption the n-3 fatty acids are poorly absorbed. Absorption may be improved by modifying the fatty acid profile of fish oil through interesterification with medium chain fatty acids. We examined the absorption of fish oil interesterified with decanoic acid in rats with normal- and malabsorption compared to a physical mixture and the fish oil itself. The interesterified fats were: 1) a regiospecific fat with decanoic acid located mainly in the sn1/3-positions and a long chain fatty acid from fish oil in the sn2-position, 2) a fat with a random distribution of fatty acids in all positions of the triacylglycerol. The main mesenteric lymph duct was cannulated for collection of lymph. In the malabsorbing rats the common bile duct was cannulated as well to divert both pancreatic juice and bile. The fatty acid composition in lymph samples collected for 24 hours was determined. Accumulated transport of n-3 fatty acids from fish oil was improved in malabsorbing rats and recoveries of fatty acids after 24 hours were improved in both rats with normal- and malabsorption administered the randomized fat compared to fish oil.

Structured lipids improve fat absorption in normal and malabsorbing rats.

The presence of medium-chain fatty acids in dietary fatty acid as well as the triacylglycerol structure may influence the absorption and lymphatic transport of fatty acids. We compared the lymphatic transport and recovery of fatty acids from four intragastrically administered fats based on rapeseed oil and decanoic acid in two rat models of normal absorption and malabsorption, respectively. The fats were: 1) a fat with a regiospecific structure, 2) a similar fat but with a random distribution of fatty acids in the triacylglycerol molecule, 3) a physical mixture of tridecanoin and rapeseed oil and 4) rapeseed oil as control. Lymph samples were collected for 24 h. Significantly higher recoveries were observed of total fatty acids, oleic acid, linoleic acid and linolenic acid from the specific oil in malabsorbing rats and of linoleic acid in normal rats fed specific oil compared with those fed rapeseed oil. Furthermore, the recoveries of oleic acid and linolenic acid from the specific oil in normal rats were higher than those from the other oils. In malabsorbing rats, the transport of all fats was approximately 90% less than that of normal rats. The present study demonstrates improved hydrolysis and absorption of the specific oil compared with the other oils examined both in rats with normal absorption and in rats with malabsorption.

Lymphatic fatty acid absorption profile during 24 hours after administration of triglycerides to rats.

In this study we determined in rats the complete 24-h lymphatic fatty acid profile after administration of either rapeseed oil (RO) or rapeseed oil interesterified with 10:0 (RO/C10) with special emphasis on the transition from absorptive to postabsorptive phase. Rats were subjected to cannulation of the main mesenteric lymph duct and the next day oils were administered through a gastric feeding tube. Lymph was collected in 1-h fractions for the following 24 h. The time for maximum lymphatic transport of fatty acids was at 4 h with fast changes in fatty acid composition from the fatty acids of endogenous origin to those of the administered oils. Seven to eight hours after administration the transport was significantly lower than maximum, indicating the change from absorptive to postabsorptive phase. At 24 h after administration of either oil the transport of total fatty acids, palmitic acid (16:0), and linoleic acid (18:2n-6) together with oleic acid (18:1 n-9) after RO had not returned to the transport at baseline. In contrast, the transport of decanoic acid (10:0) and alpha-linolenic acid (18:3n-3) returned to baseline values between 12 and 15 h. This indicated that the absorption of purely exogenous fatty acids (illustrated by 10:0 and 18:3n-3) was complete at 15 h and that the fatty acids transported between 15 and 24 h were derived mostly from endogenous stores.

Staurosporine-induced cell death in Tetrahymena thermophila has mixed characteristics of both apoptotic and autophagic degeneration.

Staurosporine blocks signal transduction associated with cell survival, proliferation and chemosensory behaviour in the ciliated protozoan, Tetrahymena thermophila. Staurosporine inhibits cell proliferation and in vivo protein phosphorylation induced by phorbol ester. It also reduces the in vitro phosphorylation of the PKC-specific substrate, myelin basic protein fragment 4-14. Our results show that cell death in the presence of staurosporine is associated with morphological and ultrastructural changes similar to both apoptosis and autophagic degeneration, but these in turn can be postponed or prevented by 8-bromo-cyclic GMP, protoporphyrin IX, hemin or actinomycin D, although phorbol ester and insulin were ineffective. The results support the notion that staurosporine-induced cell death is an active process, associated with and/or requiring de novo RNA synthesis.

Effects of protein kinase C activators and staurosporine on protein kinase activity, cell survival, and proliferation in Tetrahymena thermophila.

Autocrine factors prevent cell death in the ciliate Tetrahymena thermophila, a unicellular eukaryote, in a chemically defined medium. At certain growth conditions these factors are released at a sufficient concentration by > 500 cells ml-1 to support cell survival and proliferation. The protein kinase C activators phorbol 12-myristate 13-acetate (PMA) or 1-oleyl 2-acetate glycerol (OAG) when added to 250 cells ml-1 supported cell survival and proliferation. In the presence of the serine and threonine kinase inhibitor staurosporine the cells died both at 250 cells ml-1 in cultures supplemented with either PMA or OAG, or at 2,500 cells ml-1. At 500 cells ml-1 PMA induced the in vivo phosphorylation of at least six proteins. The myelin basic protein fragment 4-14 was phosphorylated in vitro in crude extracts of a culture of 250,000 cells ml-1. Both the in vivo and the in vitro phosphorylation were inhibited by staurosporine.