Subdural electrode recording of generalized photoepileptic responses.

We evaluated the spatiotemporal distribution of photic driving (PDR), photoparoxysmal (PPR), and photoconvulsive (PCR) responses recorded by intracranial electrodes (ic-EEG) in a patient with generalized photosensitivity and right frontal lobe cortical dysplasia. Intermittent light stimulation (ILS) was performed thirteen times in nine days. Cortical responses to ILS recorded by ic-EEG were reviewed and classified as PDRs, PPRs, and PCRs. Photic driving responses were restricted to the occipital lobe at ILS frequencies below 9 Hz, spreading to the parietal and central regions at > 9 Hz. Photoparoxysmal responses commonly presented as focal, medial occipital, and parietal interictal epileptic discharges (IEDs), the latter propagating to the sensorimotor cortices. Generalized IEDs were also generated in the setting of PPRs. Photoconvulsive responses, characterized by repetitive bilateral upper extremity myoclonus sustained until the end of the stimulus, were associated with propagation of the medial parieto-occipital discharge to the primary sensorimotor and supplementary area cortices, while generalized myoclonic seizures were associated with a generalized spike-and-wave discharge with an interhemispheric posterior cingulate onset sparing the sensorimotor cortices. Both types of PCR could occur during the same stimulus. Regardless of the pathway, PCRs only occurred when PDRs involved the parietal cortices. While there may be more than one pathway underlying PCRs, parietal lobe association cortices appear to be critical to their generation.

Dietary accumulation efficiencies and biotransformation of polybrominated diphenyl ethers in farmed Atlantic salmon (Salmo salar).

The consumer safety of farm-raised salmon could be improved by determining the transfer efficiency of hazardous pollutants from fish feed to the salmon. A controlled feeding trial for 30 weeks was carried out to investigate the transfer of polybrominated diphenyl ethers (PBDEs) in Atlantic salmon (Salmo salar). Using three feed concentrations, an average of 95% of the total PBDE content of feed accumulated in whole salmon. Skinned fillet accumulated 42-59% of the PBDE intake. Equal partitioning according to the lipid content of the tissue was demonstrated. The formation of less brominated PBDEs via preferential debromination from the meta-position was thought to explain the exceptional accumulation efficiencies of BDE 47, BDE 66, BDE 75, BDE 119 and BDE 183 that were either >100% or else increasing with the exposure dose. Monitoring of a larger number of PBDE congeners is recommended to verify the biotransformation routes. The PBDE concentration in salmon of different ages, fed on a known concentration of PBDEs in fish feed, could be predicted by using the accumulation efficiencies determined in this study.

Cataract formation in Atlantic salmon, Salmo salar L., smolt relative to dietary pro- and antioxidants and lipid level.

The development of cataracts in Atlantic salmon, Salmo salar L., was studied in 16 groups of smolts fed diets differing in prooxidant (iron, copper, manganese) and antioxidant (vitamin E, vitamin C, astaxanthin) composition and lipid level for 23 weeks in sea water, using a 2(7-3) reduced factorial design. The seven dietary variables were systematically varied at low (requirement level and 150 g lipid kg(-1)) and high levels (below known toxic levels and 320 g lipid kg(-1)). A mean endpoint cataract incidence of approximately 36% was observed. High dietary levels of vitamin C and astaxanthin reduced cataract frequency, whereas high dietary lipid level, iron and manganese were associated with increased cataract frequencies. Considering the nutritional status of selected organs of the fish, only the status of ascorbic acid correlated negatively to cataract development (P < 0.05). The lens glutathione (GSH) status was not correlated to cataract frequency, nor statistically explained by the dietary variables. However, the study shows that balancing the diet with respect to pro- and antioxidant nutrients may significantly protect Atlantic salmon against development of cataracts. An incidence of reversible osmotic cataract observed at week 14 was positively correlated to plasma glucose concentration.

Lipid metabolism and tissue composition in Atlantic salmon (Salmo salar L.)--effects of capelin oil, palm oil, and oleic acid-enriched sunflower oil as dietary lipid sources.

Triplicate groups of Atlantic salmon (Salmo salar L.) were fed four diets containing different oils as the sole lipid source, i.e., capelin oil, oleic acid-enriched sunflower oil, a 1:1 (w/w) mixture of capelin oil and oleic acid-enriched sunflower oil, and palm oil (PO). The beta-oxidation capacity, protein utilization, digestibility of dietary fatty acids and fatty acid composition of lipoproteins, plasma, liver, belly flap, red and white muscle were measured. Further, the lipid class and protein levels in the lipoproteins were analyzed. The different dietary fatty acid compositions did not significantly affect protein utilization or beta-oxidation capacity in red muscle. The levels of total cholesterol, triacylglycerols, and protein in very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and plasma were not significantly affected by the dietary fatty acids. VLDL, LDL, and HDL fatty acid compositions were decreasingly affected by dietary fatty acid composition. Dietary fatty acid composition significantly affected both the relative fatty acid composition and the amount of fatty acids (mg fatty acid per g tissue, wet weight) in belly flap, liver, red and white muscle. Apparent digestibility of the fatty acids, measured by adding yttrium oxide as inert marker, was significantly lower in fish fed the PO diet compared to the other three diets.

Collagen content in farmed Atlantic salmon (Salmo salar L.).

To clarify fish flesh quality problems and softening of fish muscle tissue during chilled storage, the collagen content, types I and V, and its changes in solubility during storage on ice in muscle of farmed Atlantic salmon (Salmo salar L.) were analyzed. The contents of acid-soluble, pepsin-soluble, and insoluble collagen in white muscle were determined in fresh fish muscle and after 3 days of storage in ice. The total collagen content was 2.9 g kg(-)(1) fresh weight. During storage on ice, a progressive change in solubility of muscle collagen was found. For acid- and pepsin-soluble collagen fractions, significantly higher and lower values, respectively, were detected. The presence and quantification of types I and V collagen in the different collagen fractions was determined also, but no significant difference in solubility during storage was found. The result suggested that collagen fibers of Atlantic salmon have a high solubility in acid solutions and contain few cross-links.

Methylated eicosapentaenoic acid and tetradecylthioacetic acid: effects on fatty acid metabolism.

We introduced methyl or ethyl groups to the 2- or 3-position of the eicosapentaenoic acid (EPA) molecule to investigate whether the branching of EPA could influence its hypolipidemic effect in rats. The most effective branching involved two methyl groups in the 2-position and one methyl group in the 3-position. These EPA derivatives increased hepatic mitochondrial and peroxisomal beta-oxidation and decreased plasma lipids concomitant with suppressed acetyl-coenzyme A (CoA) carboxylase (EC 6.4.1.2) and fatty acid synthase (EC 2.3.1.85) activities. This was followed by elevated activities of camitine O-palmitoyltransferase (EC 2.3.1.21) and possibly 2,4-dienoyl-CoA reductase (EC 1.3.1.34), as well as induced mRNA levels of these enzymes and fatty acyl-CoA oxidase. The fatty acid composition in liver changed, with an increased 18:1 n-9 content, whereas the expression of delta9-desaturase remained unchanged. We investigated the flux of fatty acids in cultured hepatocytes, and found that oxidation of [1-14C]-labeled palmitic acid increased but the secretion of palmitic acid-labeled triglycerides decreased after addition of 2-methyl-EPA. The fatty acyl-CoA oxidase (EC 1.3.3.6) activity in these cells remained unchanged. A significant negative correlation was obtained between palmitic acid oxidation and palmitic acid-labeled synthesized triglycerides. To investigate whether the hypolipidemic effect occurred independently of induced peroxisomal beta-oxidation, we fed rats 2-methyl-tetradecylthioacetic acid. This compound increased the peroxisomal but not the mitochondrial beta-oxidation, and the plasma lipid levels were unchanged. In conclusion, EPA methylated in the 2- or 3-position renders it more potent as a hypolipidemic agent. Furthermore, this study supports the hypothesis that the mitochondrion is the primary site for the hypolipidemic effect.

Carnitine palmitoyltransferase I, carnitine palmitoyltransferase II, and acyl-CoA oxidase activities in Atlantic salmon (Salmo salar).

Salmon farmers are currently using high-energy feeds containing up to 35% fat; the fish's capability of fully utilizing these high-energy feeds has received little attention. Carnitine is an essential component in the process of mitochondrial fatty acid oxidation and, with the cooperation of two carnitine palmitoyltransferases (CPT-I and CPT-II) and a carnitine acylcarnitine transporter across the inner mitochondrial membrane, acts as a carrier for acyl groups into the mitochondrial matrix where beta-oxidation occurs. However, no reports are available differentiating between CPT-I and CPT-II activities in fish. In order to investigate the potential for fatty acid catabolism, the activities of key enzymes involved in fatty acid oxidation were determined in different tissues from farmed Atlantic salmon (Salmo salar), i.e., acyl-CoA oxidase (ACO) and CPT-I and CPT-II. Malonyl-CoA was a potent inhibitor of CPT-I activity not only in red muscle but also in liver, white muscle, and heart. By expressing the enzyme activities per wet tissue, the CPT-I activity of white muscle equaled that of the red muscle, both being >> liver. CPT-II dominated in red muscle whereas the liver and white muscle activities were comparable. ACO activity was high in the liver regardless of how the data were calculated. Based on the CPT-II activity and total palmitoyl-L-carnitine oxidation in white muscle, the white muscle might have a profound role in the overall fatty acid oxidation capacity in fish.

The major histocompatibility complex in fish.

The first major histocompatibility complex (MHC) molecule in fish was identified in 1990 using a polymerase chain reaction strategy with degenerate primers (thereby avoiding the problem of low sequence similarity between higher vertebrates and fish). Since that time, MHC in fish has attracted much attention, partly due to evolutionary aspects and partly because of the potential practical consequences for future fish breeding. Knowledge of the MHC molecules in fish has thus been growing extremely rapidly. All current data point to a functional MHC system in fish. There seem to be many loci and many alleles for both classes of MHC molecules, but a lack of knowledge about functional loci versus pseudogenes and non-classical loci is making it difficult at present to establish the exact number found within each species. Fish create a few surprises, such as the lack of a link between class I and class II regions in at least two teleost species. Data on other molecules which are physically or functionally linked to the MHC genes are currently emerging. To date, no studies have established the functional implications of the MHC molecules in fish but, considering the molecular data available, such an achievement will undoubtedly occur soon. Fish may well offer a unique opportunity for identifying correlations of MHC with resistance or susceptibility to diseases.

Cloning, expression and map assignment of chicken prosaposin.

Prosaposin is the precursor of four small glycoproteins, saposins A-D, that activate lysosomal sphingolipid hydrolysis. A full-length cDNA encoding prosaposin from chicken brain was isolated by PCR. The deduced amino acid sequence predicted that, similarly to human and other mammalian species studied, chicken prosaposin contains 518 residues, including four domains that correspond to saposins A-D. There was 59% identity and 76% similarity of human and chicken prosaposin amino acid sequences. The basic three-dimensional structures of these saposins is predicted to be similar on the basis of the conservation of six cysteine residues and an N-glycosylation site. Identity of amino acid sequences was higher among saposins A, B and D than in saposin C. The predicted amino acid sequence of saposin B matched exactly that of purified chicken saposin B protein. The chicken prosaposin gene was mapped to a single locus, PSAP, in chicken linkage group E11C10 and is closely linked to the ACTA2 locus. This confirms the homology between chicken and human prosaposins and defines a new conserved segment with human chromosome 10q21-q24.

Supplementary selenium influences the response to fatty acid-induced oxidative stress in humans.

The mutual influences of wheat selenium (Se) and n-3 polyunsaturated fatty acids (n-3 PUFA) on plasma Se and indicators of increased oxidative stress were investigated in a randomized, double-blind study with 31 women (23.5 +/- 3.4 yr). Groups 1 and 2 ingested 5.4 g n-3 PUFA daily (as ethyl esters), whereas groups 3 and 4 received placebo capsules. Groups 2 and 3 received 3 slices of high-Se bread daily, providing 115 micrograms Se, in addition to the 77 +/- 26 micrograms Se in the diet. Groups 1 and 4 received placebo slices. Blood samples were drawn at baseline and at 3 and 6 wk. Serum Se concentrations increased in both groups given Se-enriched bread, but significantly less in subjects given n-3 PUFA (group 2). There were no changes in the plasma ratio alpha-tocopherol:mg cholesterol or plasma ascorbic acid levels. In group 1, plasma-conjugated dienes and thiobarbituric acid-reactive substances (TBARS) rose by 130% (p < 0.005) and 126% (p < 0.005), respectively. Two-way ANOVA showed significant interaction effects of Se and n-3 PUFA on changes in conjugated dienes (p = 0.03) and TBARS (p = 0.015), Se treatment apparently modifying the peroxidative effects of n-3 PUFA. In subjects receiving n-3 PUFA, changes in conjugated dienes and TBARS were negatively correlated with changes in serum Se. In summary, n-3 PUFA modified the effect of Se supplementation, whereas Se seemed to modify the peroxidative effects of n-3 PUFA.

Effect of 3-thia fatty acids on the lipid composition of rat liver, lipoproteins, and heart.

To investigate the importance of factors influencing the fatty acid composition, lipid and lipoprotein metabolism in the rat, the effect of 3-thia fatty acids of chain-length ranging from octyl- to hexadecylthioacetic acid were studied. In liver, very low density lipoprotein (VLDL), and low density lipoprotein (LDL), the hypolipidemic 3-thia fatty acids, namely C12-S-acetic acid to C14-S-acetic acid increased the amount of monoenes, especially oleic acid (18:ln-9). In contrast, the content of polyunsaturated fatty acids in liver, VLDL, and LDL decreased, mostly attributed to a reduction of eicosapentaenoic acid (EPA, 20:5n-3). Noteworthy, the hypolipidemic 3-thia fatty acids reduced the amount of arachidonic acid (AA, 20:4n-6) in LDL and HDL. 3-Thia fatty acids accumulated in the liver. In heart, as in liver, 3-thia fatty acids replaced fatty acids of chain-length homologues. In contrast to liver, we were unable to detect any changes in 18:ln-9. However, the n-3 polyunsaturated fatty acid content increased, particularly 20:5n-3 and docosahexaenoic acid (DHA, 22:6n-3) leading to an increased n-3/n-6 ratio. In conclusion, this study demonstrates that hypolipidemic 3-thia fatty acids change the fatty acid composition of organs and lipoproteins. These changes are linked to the expression and activity of hepatic delta9-desaturase, fatty acid oxidation, and displacement of normal fatty acids by 3-thia fatty acids. The fatty acid composition is regulated differently in liver and heart after administration of hypolipidemic 3-thia fatty acids.

Segregation studies and linkage analysis of Atlantic salmon microsatellites using haploid genetics.

A genetic marker map of Atlantic salmon would facilitate the identification of loci influencing economically important traits. In the present paper we describe five new Atlantic salmon microsatellites. Segregation studies and linkage analysis of these and previously published microsatellites were carried out in pedigrees consisting of diploid dams and haploid gynogenetic offspring. We confirm earlier reports that salmon microsatellites tend to have a higher number of repeat units than those of mammals. Linkage analysis revealed that three microsatellites belong to a linkage group spanning approximately 50 cM of the genome, whereas the remaining 10 markers seem to be unlinked.

Vitamins C and E interact in juvenile Atlantic salmon (Salmo salar, L.).

A two way regression study was performed to investigate the interactions between vitamins C and E, and the influence of dietary vitamin C on the development of vitamin E deficiency in first feeding Atlantic salmon. The fish were fed three levels of all-rac-alpha-tocopheryl acetate (0, 150, and 300 mg/kg), each with six levels of ascorbate monophosphate (0, 7.5, 15, 30, 45, and 60 mg/kg ascorbic acid equivalents). Vitamin C protected the fish against vitamin E deficiency in a dose dependent manner, as seen from the data on growth, mortality, hematology, and lipid oxidation in the liver, indicated by the concentration of malondialdehyde. Vitamin C did not influence the tissue levels of vitamin E, except in vitamin C deficiency, which induced a large drop in liver vitamin E concentration. The liver level of vitamin C increased in response to supplementation of both vitamins. The results indicate two different interaction mechanisms: a synergistic effect of simultaneous protection of the water and lipid phases against oxidation, and regeneration of vitamin E from the vitamin E radical by ascorbic acid.

Sequence analysis of MHC class I alpha 2 domain exon variants in one diploid and two haploid Atlantic salmon pedigrees.

Genetic diversity in the second domain exon of Atlantic salmon (Salmo salar) major histocompatibility complex (Mhc) class I was investigated in two dams and nine of their haploid offspring by means of polymerase chain reaction (PCR) and DNA sequence analysis. A similar study was also performed on nine diploid offspring from one of these dams. The complex segregation patterns and sequence similarities between variants make definitive allele, haplotype and locus assignments difficult. There are, however, indications of six Mhc-Sasa class I loci and a fairly well-defined haplotype of four variants. One non-polymorphic variant present in most specimens could be a salmon analogue to the human non-classical loci.

Eicosapentaenoic acid, but not docosahexaenoic acid, increases mitochondrial fatty acid oxidation and upregulates 2,4-dienoyl-CoA reductase gene expression in rats.

The aim of the present study was to investigate whether eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) was responsible for the triglyceride-lowering effect of fish oil. In rats fed a single dose of EPA as ethyl ester (EPA-EE), the plasma concentration of triglycerides was decreased at 8 h after acute administration. This was accompanied by an increased hepatic fatty acid oxidation and mitochondrial 2,4-dienoyl-CoA reductase activity. The steady-state level of 2,4-dienoyl-CoA reductase mRNA increased in parallel with the enzyme activity. An increased hepatic long-chain acyl-CoA content, but a reduced amount of hepatic malonyl-CoA, was obtained at 8 h after acute EPA-EE treatment. On EPA-EE supplementation, both EPA (20:5n-3) and docosapentaenoic acid (DPA, 22:5n-3) increased in the liver, whereas the hepatic DHA (22:6n-3) concentration was unchanged. On DHA-EE supplementation retroconversion to EPA occurred. No statistically significant differences were found, however, for mitochondrial enzyme activities, malonyl-CoA, long-chain acyl-CoA, plasma lipid levels, and the amount of cellular fatty acids between DHA-EE treated rats and their controls at any time point studied. In cultured rat hepatocytes, the oxidation of [1-14C]palmitic acid was reduced by DHA, whereas it was stimulated by EPA. In the in vivo studies, the activities of phosphatidate phosphohydrolase and acetyl-CoA carboxylase were unaffected after acute EPA-EE and DHA-EE administration, but the fatty acyl-CoA oxidase, the rate-limiting enzyme in peroxisomal fatty acid oxidation, was increased after feeding these n-3 fatty acids. The hypocholesterolemic properties of EPA-EE may be due to decreased 3-hydroxy-3-methylglutaryl-CoA reductase activity. Furthermore, replacement of the ordinary fatty acids, i.e., the monoenes (16:1n-7, 18:1n-7, and 18:1n-9) with EPA and some conversion to DPA concomitant with increased fatty acid oxidation is probably the mechanism leading to changed fatty acid composition. In contrast, DHA does not stimulate fatty acid oxidation and, consequently, no such displacement mechanism operates. In conclusion, we have obtained evidence that EPA, and not DHA, is the fatty acid primarily responsible for the triglyceride-lowering effect of fish oil in rats.

Long-term effect of tetradecylthioacetic acid: a study on plasma lipid profile and fatty acid composition and oxidation in different rat organs.

Administration of tetradecylthioacetic acid (a 3-thia fatty acid) increases mitochondrial and peroxisomal beta-oxidative capacity and carnitine palmitoyltransferase activity, but reduces free fatty acid and triacylglycerol levels in plasma compared to palmitic acid-treated rats and controls. The decrease in plasma triacylglycerol was accompanied by a reduction (56%) in VLDL-triacylglycerol. Prolonged supplementation of tetradecylthioacetic acid caused a significant increase in lipogenic enzyme activities (ATP-citrate lyase and acetyl-CoA carboxylase) and diacylglycerol acyltansferase, but did not affect phosphatidate phosphohydrolase. Plasma cholesterol, LDL- and HDL-cholesterol levels were reduced. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase activity was, however, stimulated in 3-thia fatty acid-treated rats compared to controls. In addition. the mRNAs of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and LDL-receptor were increased. Tetradecylthioacetic acid administration affected the fatty acid composition in plasma and liver by increasing the amount of monoenes, especially 18:1(n-9), mostly at the expense of omega-3 fatty acids. Compared to liver a large amount of tetradecylthioacetic acid accumulated in the heart, and this accumulation was accompanied by an increase in omega-3 fatty acids, particularly 22:6(n-3) and a decrease in omega-6 fatty acids, mainly 20:4(n-6). The results show that the hypolipidemic effect of tetradecylthioacetic acid is sustained after prolonged administration and may, at least in part, be due to increased fatty acid oxidation and upregulated LDL-receptor gene expression. The increase in lipogenic enzyme activities as well as increased 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity, may be compensatory mechanisms to maintain cellular integrity. Decreased level of 20:4(n-6) combined with increased omega-3/omega-6 ratio in cardiac tissue after tetradecylthioacetic acid treatment may have influence on membrane dynamics and function.

Chronic administration of eicosapentaenoic acid and docosahexaenoic acid as ethyl esters reduced plasma cholesterol and changed the fatty acid composition in rat blood and organs.

Fish oils rich in n-3 fatty acids have been shown to decrease plasma lipid levels, but the underlying mechanism has not yet been elucidated. This investigation was performed in order to further clarify the effects of purified ethyl esters of eicosapentaenoic acid (EPA-EE) and docosahexaenoic acid (DHA-EE) on lipid metabolism in rats. The animals were fed EPA-EE, DHA-EE, palmitic acid, or corn oil (1 g/kg/d) by orogastric intubation along with a chow background diet for three months. At the end the animals were sacrificed. Plasma and liver lipids were measured, as well as lipid-related enzyme activities and mRNA levels. The fatty acid composition of plasma and different tissues was also determined. This study shows that, compared to the corn oil control, EPA-EE and DHA-EE lowered plasma cholesterol level, whereas only EPA-EE lowered the amount of plasma triacylglycerol. In liver peroxisomes, both EE preparations increased fatty acyl-CoA oxidase FAO activities, and neither altered 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase activities. In liver microsomes, EPA-EE raised HMG-CoA reductase and acyl-CoAicholesterol acyltransferase activities, whereas DHA-EE lowered the former and did not affect the latter. Neither product altered mRNA levels for HMG-CoA reductase, low density lipoprotein-receptor, or low density lipoprotein-receptor related protein. EPA-EE lowered plasma triacylglycerol, reflecting lowered very low density lipoprotein secretion, thus the cholesterol lowering effect in EPA-EE-treated rats may be secondary to the hypotriacylglycerolemic effect. An inhibition of HMG-CoA reductase activity in DHA-EE treated rats may contribute to the hypocholesterolemic effect. The present study reports that 20:5n-3, and not 22:6n-3, is the fatty acid primarily responsible for the triacylglycerol lowering effect of fish oil. Finally, 20:5n-3 was not converted to 22:6n-3, whereas retroconversion of 22:6n-3 to 20:5n-3 was observed.