Dipeptide nanotubes, with n-terminally located omega-amino acid residues, that are stable proteolytically, thermally, and over a wide range of pH

Two dipeptides containing an N-terminally positioned omega-amino acid residue (beta-alanine/delta-amino valeric acid) self-assembles to form nanotubes in the solid state as well as in aqueous solution. In spite of having hollow nanotubular structures in the solid state and in solution, their self-assembling nature in these two states are different and this leads to the formation of different internal diameters of these nanotubes in solution and in solid state structure. These nanotubes are stable proteolytically, thermally, and over a wide range of pH values (1-13). The role of water molecules in nanotube formation has been investigated in the solid state. These nanotubes can be considered as a new class of dipeptide nanotubes as they are consisting of N-terminally located protease resistant omega-amino acid residues and C-terminally positioned alpha-amino acid residues. These dipeptides can form an interesting class of short peptidic structure that can give rise to stable nanotubular structure upon self-assembly and these nanotubes can be explored in future for potential nanotechnological applications.

Fatty acids and immune function: new insights into mechanisms

Fatty acids are known to play diverse roles in immune cells. They are important as a source of energy, as structural components of cell membranes, as signaling molecules and as precursors for the synthesis of eicosanoids and similar mediators. Recent research has suggested that the localization and organisation of fatty acids into distinct cellular pools has a direct influence on the behaviour of a number of proteins involved in immune cell activation, including those associated with T cell responses, antigen presentation and fatty acid-derived inflammatory mediator production. This article reviews these studies and places them in the context of existing literature in the field. These studies indicate the existence of several novel mechanisms by which altered fatty acid availability can modulate immune responses and impact upon clinical outcomes

Fatty acids and the immune system: from basic science to clinical applications

Over the last 25 years, the effects of fatty acids on the immune system have been characterized using in vitro, animal and human studies. Advances in fatty acid biochemistry and molecular techniques have recently suggested new mechanisms by which fatty acids could potentially modify immune responses, including modification of the organization of cellular lipids and interaction with nuclear receptors. Possibilities for the clinical applications of n-3 PUFA are now developing. The present review focuses on the hypothesis that the anti-inflammatory properties of n-3 PUFA in the arterial wall may contribute to the protective effects of n-3 PUFA in CVD, as suggested by epidemiological and secondary prevention studies. Studies are just beginning to show that dietary n-3 PUFA can be incorporated into plaque lipid in human subjects, where they may influence the morphology and stability of the atherosclerotic lesion.

Composition, color, and texture of Thai indigenous and broiler chicken muscles

Chemical compositions and physical properties of mixed-sex Thai indigenous (Gallus domesticus) and broiler (commercial breed, CP707) chicken biceps femoris and pectoralis muscles were determined. Indigenous chicken muscles contained higher protein contents but lower fat and ash contents compared to broiler muscles (P < 0.001). The amino acid profile of the indigenous chicken muscles was similar to that of the broiler muscles except they were slightly richer in glutamic acid (P < 0.05). The indigenous chicken muscles contained more saturated and less polyunsaturated fatty acids than the broiler muscles. There were no differences in the monounsaturated fatty acid contents between the breeds. The total collagen contents of indigenous pectoralis and biceps femoris muscles were 5.09 and 12.85 mg/g, respectively, which were higher than those found in broiler pectoralis (3.86 mg/g) and biceps femoris muscles (8.70 mg/g) (P < 0.001). Soluble collagen contents were lower for indigenous pectoralis and biceps femoris muscles, 22.16 vs. 31.38% and 26.06 vs. 33.87%, respectively. The CIE system values of lightness (L*), redness (a*), and yellowness (b*) of indigenous chicken muscles were higher than those of broiler muscles. The shear values of indigenous chicken muscles either raw or cooked were higher than those of broiler muscles (P < 0.05). After cooking, the shear values decreased for broiler biceps femoris and pectoralis muscles (P < 0.05), whereas no change was observed for indigenous chicken biceps femoris muscle (P > 0.05). Shear values increased for indigenous chicken pectoralis muscle (P < 0.05).

Effects of dairy products naturally enriched with cis-9,trans-11 conjugated linoleic acid on the blood lipid profile in healthy middle-aged men

Background: Interest in the development of dairy products naturally enriched in conjugated linoleic acid (CLA) exists. However, feeding regimens that enhance the CLA content of milk also increase concentrations of trans-18:1 fatty acids. The implications for human health are not yet known. Objective: This study investigated the effects of consuming dairy products naturally enriched in cis-9,trans-11 CLA (and trans-11 18:1) on the blood lipid profile, the atherogenicity of LDL, and markers of inflammation and insulin resistance in healthy middle-aged men. Design: Healthy middle-aged men (n = 32) consumed ultra-heat-treated milk, butter, and cheese that provided 0.151 g/d (control) or 1.421 g/d (modified) cis-9,trans-11 CLA for 6 wk. This was followed by a 7-wk washout and a crossover to the other treatment. Results: Consumption of dairy products enriched with cis-9,trans-11 CLA and trans-11 18:1 did not significantly affect body weight, inflammatory markers, insulin, glucose, triacylglycerols, or total, LDL, and HDL cholesterol but resulted in a small increase in the ratio of LDL to HDL cholesterol. The modified dairy products changed LDL fatty acid composition but had no significant effect on LDL particle size or the susceptibility of LDL to oxidation. Overall, increased consumption of full-fat dairy products and naturally derived trans fatty acids did not cause significant changes in cardiovascular disease risk variables, as may be expected on the basis of current health recommendations. Conclusion: Dairy products naturally enriched with cis-9,trans-11 CLA and trans-11 18: 1 do not appear to have a significant effect on the blood lipid profile.

Trans-fatty acids and cancer: the evidence reviewed

The present review comes from the authors of the recent Scientific Advisory Committee on Nutrition (SACN) review Update on Trans Fatty Acids and Health, and focuses on assessing the strength of the evidence for a link between trans-fatty acid (trans-FA) intake and cancer. It evaluates a range of human ecological, case-control and prospective studies with trans-FA exposure assessed using either dietary assessment methods or trans-FA levels in tissues. Relevant animal studies are also presented in order to elucidate potential mechanisms. It concludes that there is weak and inconsistent evidence for a relationship between trans-FA and breast or colorectal cancer. Evidence for an association between trans-FA and prostate cancer is limited, but a recent large case-control study has shown a strong interaction between risk and trans-FA intake for the RNASEL QQ/RQ genotype that is present in about 35% of the population. This potential association requires further investigation. The single study on non-Hodgkin's lymphoma reported a strong positive association, but out), used a single assessment of dietary trans-FA made at the start of the study in 1980, and the significant changes it) trans-FA intakes between then and the end Of follow-up in 1994 limit the reliability of this observation. There is insufficient evidence to allow any differentiation between the effects of trans-FA from animal or vegetable origin on cancer risk.

Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial

Background N-3 polyunsaturated fatty acids (PUFAs) from oily fish protect against death from cardiovascular disease. We aimed to assess the hypothesis that incorporation of n-3 and n-6 PUFAs into advanced atherosclerotic plaques increases and decreases plaque stability, respectively. Methods We did a randomised controlled trial of patients awaiting carotid endarterectomy. We randomly allocated patients control, sunflower oil (n-6), or fish-oil (n-3) capsules until surgery. Primary outcome was plaque morphology indicative of stability or instability, and outcome measures were concentrations of EPA, DHA, and linoleic acid in carotid plaques; plaque morphology; and presence of macrophages in plaques. Analysis was per protocol. Findings 188 patients were enrolled and randomised; 18 withdrew and eight were excluded. Duration of oil treatment was 7-189 days (median 42) and did not differ between groups. The proportions of EPA and DHA were higher in carotid plaque fractions in patients receiving fish oil compared with those receiving control (absolute difference 0.5 [95% CI 0.3-0.7], 0.4 [0.1-0.6], and 0.2 [0.1-0.4] g/100 g total fatty acids for EPA; and 0.3 [0.0-0.8], 0.4 [0.1-0.7], and 0.3 [0.1-0.6] g/100 g total fatty acids for DHA; in plaque phospholipids, cholesteryl esters, and triacylglycerols, respectively). Sunflower oil had little effect on the fatty acid composition of lipid fractions. Fewer plaques from patients being treated with fish oil had thin fibrous caps and signs of inflammation and more plaques had thick fibrous caps and no signs of inflammation, compared with plaques in patients in the control and sunflower oil groups (odds ratio 0.52 [95% CI 0.24-0.89] and 1.19 [1.02-1.57] vs control; 0.49 [0.23-0.90] and 1.16 [1.01-1.53] vs sunflower oil). The number of macrophages in plaques from patients receiving fish oil was lower than in the other two groups. Carotid plaque morphology and infiltration by macrophages did not differ between control and sunflower oil groups. Interpretation Atherosclerotic plaques readily incorporate n-3 PUFAs from fish-oil supplementation, inducing changes that can enhance stability of atherosclerotic plaques. By contrast, increased consumption of n-6 PUFAs does not affect carotid plaque fatty-acid composition or stability over the time course studied here. Stability of plaques could explain reductions in non-fatal and fatal cardiovascular events associated with increased n-3 PUFA intake.

Profiling of composition and metabolic activities of the colonic microflora of growing pigs fed diets supplemented with prebiotic oligosaccharides

It is evident that quantitative information on different microbial groups and their contribution in terms of activity in the gastrointestinal (GI) tract of humans and animals is required in order to formulate functional diets targeting improved gut function and host health. In this work, quantitative information on levels and spatial distributions of Bacteroides spp, Eubacterium spp, Clostridium spp, Escherichia coli, Bifidobacterium spp and Lactobacillus/Enterococcus spp. along the porcine large intestine was investigated using 16S rRNA targeted probes and fluorescent in situ hybridisation (FISH). Caecum, ascending colon (AC) and rectum luminal digesta from three groups of individually housed growing pigs fed either a corn-soybean basal diet (CON diet) or a prebiotic diet containing 10 g/kg oligofructose (FOS diet) or trans-galactooligosaccharides (TOS diet) at the expense of cornstarch were analysed. DAPI staining was used to enumerate total number of cells in the samples. Populations of total cells, Bacteroides, Eubacterium, Clostridium and Bifidobacterium, declined significantly (P < 0.05) from caecum to rectum, and were not affected by dietary treatments. Populations of Lactobacillus/ Enterococcus and E coli did not differ throughout the large intestine. The relative percent (%) contribution of each bacterial group to the total cell count did not differ between caecum and rectum, with the exception of Eubacterium that was higher in the AC digesta. FISH analysis showed that the sum of all bacterial groups made up a small percentage of the total cells, which was 12.4%, 21.8% and 10.3% in caecum, AC and rectum, respectively. This supports the view that in swine, the diversity of GI microflora might be higher compared to other species. In terms of microflora metabolic activity, the substantially higher numerical trends seen in FOS and TOS treatments regarding total volatile fatty acid, acetate concentrations and glycolytic activities, it could be postulated that FOS and TOS promoted saccharolytic activities in the porcine colon. (c) 2006 Elsevier Ltd. All rights reserved.

Nutrient gene interactions in lipid metabolism

Purpose of review To summarize recent findings relating to the impact of dietary fat composition on whole body lipid metabolism, and common gene variants on the blood lipid response to dietary fat change. Recent findings In recent years a more comprehensive understanding of the impact of polyunsaturated fat (PUFA) intake on the regulation of transcription factors involved in lipogenesis and fatty acid and lipoprotein metabolism has emerged. The evidence is suggestive of a greater potency of the long chain n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and in particular their oxidative products, relative to n-6 Pi In the area of nutrigenetics a number of common gene variants have been identified which may be important determinants of the blood lipid response to altered dietary fat composition. However, confirmation of associations in independent cohorts, and an understanding of the size effect of individual or combinations of genotypes, is often lacking. Summary Although in the future, genotyping holds the potential as a public health tool to target and personalize dietary advice, nutrigenetics is a relatively new science, and further research is needed to address the existing inconsistencies and knowledge gaps.

Dietary fat composition and cardiovascular disease

Cardiovascular disease (CVD), which includes coronary heart disease and stroke, remains the major killer in the EU, being responsible for 42% of total mortality. The amount and composition of dietary fat is arguably the most important dietary factor contributing to disease risk. A significant body of consistent evidence indicates that a decrease in dietary saturated fat:unsaturated (polyunsaturated + monounsaturated) ratio and an increased intake of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) found in fish, is cardioprotective. Furthermore, although the evidence is currently less convincing, such a strategy is also likely to improve insulin sensitivity, the central metabolic defect in diabetes. Currently in the UK only 12% of men, 17% of women and 8% of children have an SFA intakes <10% of energy. The average intake of LC n-3 PUFA is <0.2 g/day, which is less than half the current conservative recommendation of a minimum of 0.45 g/day. Public health strategies to reverse these dietary fatty acid imbalances, aimed at educating and motivating the consumer and making affordable and acceptable food products with an ‘enhanced’ fatty acid profile more widely available, must remain a public health priority in the ‘fight’ against CVD.

In vitro determination of prebiotic properties of oligosaccharides derived from an orange juice manufacturing by-product stream

Fermentation properties of oligosaccharides derived from orange peel pectin were assessed in mixed fecal bacterial culture. The orange peel oligosaccharide fraction contained glucose in addition to rhamnogalacturonan and xylogalacturonan pectic oligosaccharides. Twenty-four-hour, temperature- and pH-controlled, stirred anaerobic fecal batch cultures were used to determine the effects that oligosaccharides derived from orange products had on the composition of the fecal microbiota. The effects were measured through fluorescent in situ hybridization to determine changes in bacterial populations, fermentation end products were analyzed by high-performance liquid chromatography to assess short-chain fatty acid concentrations, and subsequently, a prebiotic index (PI) was determined. Pectic oligosaccharides (POS) were able to increase the bifidobacterial and Eubacterium rectale numbers, albeit resulting in a lower prebiotic index than that from fructo-oligosaccharide metabolism. Orange albedo maintained the growth of most bacterial populations and gave a PI similar to that of soluble starch. Fermentation of POS resulted in an increase in the Eubacterium rectale numbers and concomitantly increased butyrate production. In conclusion, this study has shown that POS can have a beneficial effect on the fecal microflora; however, a classical prebiotic effect was not found. An increase in the Eubacterium rectale population was found, and butyrate levels increased, which is of potential benefit to the host.

Lack of effect of foods enriched with plant- or marine-derived n-3 fatty acids on human immune function

Background: Greatly increasing dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA)] or fish oil [rich in the long-chain n-3 PUFAs eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids] can reduce markers of immune cell function. The effects of more modest doses are unclear, and it is not known whether ALA has the same effects as its long-chain derivatives. Objective: The objective was to determine the effects of enriching the diet with ALA or EPA+DHA on immune outcomes representing key functions of human neutrophils, monocytes, and lymphocytes. Design: In a placebo-controlled, double-blind, parallel study, 150 healthy men and women aged 25-72 y were randomly assigned to I of 5 interventions: placebo (no additional n-3 PUFAs), 4.5 or 9.5 g ALA/d, and 0.77 or 1.7 g EPA+DHA/d for 6 mo. The n-3 PUFAs were provided in 25 g fat spread plus 3 oil capsules. Blood samples were taken at 0, 3, and 6 mo. Results: The fatty acid composition of peripheral blood mononuclear cell phospholipids was significantly different in the groups with higher intakes of ALA or EPA+DHA. The interventions did not alter the percentages of neutrophils or monocytes engaged in phagocytosis of Escherichia coli or in phagocytic activity, the percentages of neutrophils or monocytes undergoing oxidative burst in response to E. coli or phorbol ester, the proliferation of lymphocytes in response to a T cell mitogen, the production of numerous cytokines by monocytes and lymphocytes, or the in vivo delayed-type hypersensitivity response. Conclusion: An intake of f less than or equal to9.5 g ALA/d or less than or equal to1.7 g EPA+DHA/d does not alter the functional activity of neutrophils, monocytes, or lymphocytes, but it changes the fatty acid composition of mononuclear cells.

Chemical, physical, and sensory properties of dairy products enriched with conjugated linoleic acid

Recent studies have illustrated the effects of cis-9, trans-11 conjugated linoleic acid (CLA) on human health. Ruminant-derived meat, milk and dairy products are the predominant sources of cis-9, trans-11 CLA in the human diet. This study evaluated the processing properties, texture, storage characteristics, and organoleptic properties of UHT milk, Caerphilly cheese, and butter produced from a milk enriched to a level of cis-9, trans-11 CLA that has been shown to have biological effects in humans. Forty-nine early-lactation Holstein-British Friesian cows were fed total mixed rations containing 0 (control) or 45 g/kg ( on dry matter basis) of a mixture (1:2 wt/wt) of fish oil and sunflower oil during two consecutive 7-d periods to produce a control and CLA-enhanced milk, respectively. Milk produced from cows fed the control and fish and sunflower oil diets contained 0.54 and 4.68 g of total CLA/100 g of fatty acids, respectively. Enrichment of CLA in raw milk from the fish and sunflower oil diet was also accompanied by substantial increases in trans C18:1 levels, lowered C18: 0, cis-C18:1, and total saturated fatty acid concentrations, and small increases in n-3 polyunsaturated fatty acid content. The CLA-enriched milk was used for the manufacture of UHT milk, butter, and cheese. Both the CLA-enhanced butter and cheese were less firm than control products. Although the sensory profiles of the CLA-enriched milk, butter, and cheese differed from those of the control products with respect to some attributes, the overall impression and flavor did not differ. In conclusion, it is feasible to produce CLA-enriched dairy products with acceptable storage and sensory characteristics.

Apolipoprotein E enrichment of immuno-separated chylomicron and chylomicron remnants following saturated fatty acids

Aim: We examined the effect of meat fatty acids on lipid and apolipoprotein concentrations of very low density lipoprotein (VLDL) and chylomicron/chylomicron remnants in lipid fractions with a Svedberg flotation rate (S-f) 60-400 and S-f 20-60. Methods and results: Six healthy middle-aged men received in random order mixed meals enriched with saturated (SFA), polyunsaturated (PUFA) or monounsaturated (MUFA) fatty acids on 3 occasions. VLDL and chylomicron/chylomicron remnants in the lipid fractions were separated by immunoaffinity chromatography against apo B-100. In the S-f 60-400 chylomicron/chylomicron remnants, triacylglycerol and cholesterol concentrations were significantly tower following PUFA compared with SFA and MUFA (P <= 0.05). Apolipoprotein (apo) E responses were significantly higher after SFA in chylomicron/chylomicron remnants and VLDL compared with PUFA and MUFA (P < 0.007). However, apo B responses (particle number) were higher following MUFA than SFA (P = 0.039 for chylomicron/chylomicron remnants). Composition of the chylomicron/chylomicron remnants (expressed per particle) revealed differences in their triacylglycerol and apo E contents; in the Sf 60-400 fraction, SFA-rich chylomicron/chylomicron remnants contained significantly more triacylglycerol than MUFA (P = 0.028), more apo E than PUFA- and MUFA-rich particles (P < 0.05) and in the S-f 20-60 fraction, more apo E than MUFA (P = 0.009). Conclusion: There are specific differences in the composition of chylomicron/ chylomicron remnants formed after saturated compared with unsaturated fatty acid-rich meals which could determine their metabolic fate in the circulation and subsequent atherogenicity. (C) 2005 Elsevier B.V. All rights reserved.

Greater enrichment of triacylglycerol-rich lipoproteins with apolipoproteins E and C-III after meals rich in saturated fatty acids than after meals rich in unsaturated fatty acids

Background: Although there is considerable interest in the postprandial events involved in the absorption of dietary fats and the subsequent metabolism of diet-derived triacylglycerol-rich lipoproteins, little is known about the effects of meal fatty acids on the composition of these particles. Objective: We examined the effect of meal fatty acids on the lipid and apolipoprotein contents of triacylglycerol-rich lipoproteins. Design: Ten normolipidemic men received in random order a mixed meal containing 50 L, of a mixture of palm oil and cocoa butter [rich in saturated fatty acids (SFAs)], safflower oil [n-6 polyunsaturated fatty acids (PUFAs)]. or olive oil [monounsaturated fatty acids (MUFAs)] on 3 occasions. Fasting and postprandial apolipoproteins B-48. B-100, E. C-II, and C-III and lipids (triacylglycerol and cholesterol) were measured in plasma fractions with Svedberg flotation rates (S-f) >400 S-f 60-400, and S-f 20 - 60. Results: Calculation of the composition of the triacylglycerol-rich lipoproteins (expressed per mole of apolipoprotein B) showed notable differences in the lipid and apolipoprotein contents of the SFA-enriched particles in the S-f > 400 and S-f 60-400 fractions. After the SFA meal, triacylglycerol-rich lipoproteins in these fractions showed significantly greater amounts of triacylglycerol and of apolipoproteins C-II (Sf 60-400 fraction only), C-III, and E than were found after the MUFA meal (P < 0.02) and more cholesterol, apolipoprotein C-III (Sf > 400 fraction only), and apolipoprotein E than after the PUFA meal (P < 0.02). Conclusions: Differences in the composition of S-f > 400 and S-f 60-400 triacylglycerol-rich lipoproteins formed after saturated compared with unsaturated fatty acid-rich meals may explain differences in the metabolic handling of dietary fats.