Latest Research News on Lipemia: Dec 2020

Postprandial lipemia and cardiovascular disease

Postprandial lipemia, characterized by a rise in triglyceride-rich lipoproteins after eating, is a dynamic, nonsteady-state condition in which humans spend the majority of time. There are several lines of evidence suggesting that postprandial lipemia increases risk of atherogenesis. Clinical data show a correlation between postprandial lipoproteins and the presence/progression of coronary artery disease and carotid intimal thickness. Mechanistic studies demonstrate that triglyceride-rich lipoprotein remnants may have adverse effects on endothelium and can penetrate into the subendothelial space. Exchange of core lipids between postprandial lipoproteins and low-density lipoprotein (LDL)/high-density lipoprotein (HDL) is increased during prolonged lipemia, resulting in small, dense LDL particles and reduced HDL cholesterol levels. Hemostatic variables, including clotting factors, platelet reactivity, and monocyte cytokine expression, may be increased during postprandial lipemia. Collectively, these data suggest that assessment and treatment of atherosclerosis should include parameters related to postprandial lipemia. [1]

Dietary habits and their relations to insulin resistance and postprandial lipemia in nonalcoholic steatohepatitis

The relations of dietary habits to insulin sensitivity and postprandial triglyceride metabolism were evaluated in 25 patients with nonalcoholic steatohepatitis (NASH) and 25 age-, body mass index (BMI)-, and gender-matched healthy controls. After a 7-day alimentary record, they underwent a standard oral glucose tolerance test (OGTT), and the insulin sensitivity index (ISI) was calculated from the OGTT; an oral fat load test was also performed in 15 patients and 15 controls. The dietary intake of NASH patients was richer in saturated fat (13.7% ± 3.1% vs. 10.0% ± 2.1% total kcal, respectively, P = .0001) and in cholesterol (506 ± 108 vs. 405 ± 111 mg/d, respectively, P = .002) and was poorer in polyunsaturated fat (10.0% ± 3.5% vs. 14.5% ± 4.0% total fat, respectively, P = .0001), fiber (12.9 ± 4.1 vs. 23.2 ± 7.8 g/d, respectively, P = .000), and antioxidant vitamins C (84.3 ± 43.1 vs. 144.2 ± 63.1 mg/d, respectively, P = .0001) and E (5.4 ± 1.9 vs. 8.7 ± 2.9 mg/d, respectively, P = .0001). The ISI was significantly lower in NASH patients than in controls. Postprandial total and very low density lipoproteins triglyceride at +4 hours and +6 hours, triglyceride area under the curve, and incremental triglyceride area under the curve were higher in NASH compared with controls. Saturated fat intake correlated with ISI, with the different features of the metabolic syndrome, and with the postprandial rise of triglyceride. Postprandial apolipoprotein (Apo) B48 and ApoB100 responses in NASH were flat and strikingly dissociated from the triglyceride response, suggesting a defect in ApoB secretion. In conclusion, dietary habits may promote steatohepatitis directly by modulating hepatic triglyceride accumulation and antioxidant activity as well as indirectly by affecting insulin sensitivity and postprandial triglyceride metabolism. Our findings provide further rationale for more specific alimentary interventions, particularly in nonobese, nondiabetic normolipidemic NASH patients. [2]

Interchange of Apolipoproteins between Chylomicrons and High Density Lipoproteins during Alimentary Lipemia in Man

Apolipoproteins of the “C” group in human blood plasma, which contain the activator of the lipoprotein lipase-substrate interaction, were found to be transferred specifically from serum to phospholipid-stabilized fat emulsion. Content and distribution of apoprotein activator were measured in healthy men in the postabsorptive state and 4 h after ingestion of meals containing 100 g fat. Content of activator protein in whole serum did not change after ingestion of the fat-rich meals but that contained in triglyceride-rich lipoproteins of density (d) <1.006 approximately doubled whereas that of high density lipoproteins fell by half. The increased activator content of triglyceride-rich lipoproteins was virtually confined to chylomicrons and its concentration in chylomicron apoprotein was substantially greater than that in very low density lipoproteins. This difference could be ascribed largely to a higher content of C apoproteins in chylomicron protein since both the concentration of C apoproteins and of apoprotein activator were directly proportional to particle diameter while the pattern of fast-migrating C apoproteins in polyacrylamide gels was similar among chylomicrons and subfractions of very low density lipoproteins. Apparent concentration of activator protein was much greater in the high density lipoprotein subfraction of d 1.063-1.125 than in the subfraction of d 1.125-1.21. In the subfraction of d 1.063-1.125, the concentration of activator protein and of fast-migrating C apoproteins in polyacrylamide gels decreased after the fat-rich meal. Concentration of phospholipids in this fraction increased gradually to a peak 43% above the basal value 6 h after the meal. The results obtained demonstrate that high density lipoproteins contribute certain functionally important polar constituents to chylomicrons during alimentary lipemia in man and suggest that they also receive surface constituents from chylomicrons during the course of their metabolism. [3]

Portulaca oleracea Reduces Lipemia, Glycemia, and Oxidative Stress in Streptozotocin-induced Diabetic Rats Fed Cholesterol-enriched Dietq

Aims: In this study, the effects of Portulaca oleracea (Po) in the treatment of hypercholesterolemia combined with diabetes in rats were investigated.

Place and Duration of Study: Laboratory of Clinical and Metabolic Nutrition, Department of Biology, Nature and Life Sciences Faculty, University of Oran1, Algeria, between September and July 2017.

Study Design: The effects of an aqueous extract from the leaves of Po were studied on glucose homeostasis, lipid parameters, and oxidative stress markers, in streptozotocin (STZ) induced diabetic rats on a cholesterol-enriched diet.

Methodology: Experimental hypercholesterolemia was induced by feeding rats with 1% cholesterol-enriched diet for 15 days. Hypercholesterolemic male Wistar rats (n=28) were rendered diabetic by a single intraperitoneal injection dose (55 mg/kg BW) of STZ. Hypercholesterolemic diabetic rats were divided into two groups (n=10): Hypercholesterolemic diabetic group (HC-D), and hypercholesterolemic-diabetic group supplemented with 1% of Po aqueous extract (HC-DPo) during 28 days. Assessed parameters were blood glucose, insulinemia, glycosylated haemoglobin (HbA1c), liver and plasma lipids, lipid peroxidation, and antioxidant enzymes in plasma, red blood cells (RBCs), and tissues.

Results: A significant increase in final body weight was found between both groups. In HC-DPo vs HC-D group, glycemic parameters were improved by decreasing glucose, HbA1C levels, and by enhancing insulinemia. Low plasma values of  total cholesterol (TC) (-42%), triacylglycerols (TG) (-63%), very low and low density lipoprotein cholesterol (VLDL-C, LDL-C) (-66% and -80%), and increase of high density lipoprotein cholesterol (HDL-C) (-26%), leading to decreased atherogenic indices TC/HDL-C (-57%) and LDL-C/HDL-C (-85%) were noted in rats treated by Po compared to untreated group. In the liver, heart and aorta, lipid peroxidation was lowered, and inversely, antioxidant enzymes activities were increased after treatment with Po.

Conclusion: On the basis of these finding, it can be concluded that the Po aqueous extract is an interesting natural product to prevent hypercholesterolemia in diabetic rats. Protocols in hypercholesterolemia diabetic patients are needed to verify and validate these results. [4]

Performance of Brioler Chickens and mRNA Expression of Liver Fatty Acid Binding Protein Gene Fed with Soybean

Aims: An experiment was conducted to investigate the effects of different levels of processed full-fat soy bean on performance, Lipid blood carcass quality and mRNA expression levels of liver fatty-acid binding protein (LFABP) in broiler chicks.

Study Design: A total of 240 day-old male broilers (Ross 308) was used in a completely randomized design.

Place and Duration of Study: Islamic Azad University, Kashmar Branch Farm, 42 days.

Methodology: Experimental treatments included a control treatment (corn-soybean meal), levels 8 and 12% roasted full-fat soybean and levels 8 and 12% extruded full-fat soybean in rations .Each dietary treatment was assigned to four replicate pens holding 12 male broiler chicks. Roasting was conducted for 20 seconds at a temperature of 110°c and extruding for 90 seconds at a temperature of 170°C. Weight gains, feed intake and feed conversion ratio were measured at the end of each experimental period (10, 24, and 42 days of age). At the end of experimental periods, blood samples were collected from wing vein to measure the serum trigeliserids cholesterol, LDL and HDL levels.

Results: The effect of diets on feed conversion ratio was significant at each periods, as well as total period although it was just significant on increasing of growth rate and decreasing of feed intake at grower and finisher periods (p<0.05). Results of the carcass evaluation were not significant. Reduction of pancreas relative weight was only observed in treatments contained roasted and extruded soybean. Replacing extruded and roasted soybean with soybean meal caused a reduction trend of blood cholesterols, triglyceride and LDL, which was statistically significant. The results showed that the mRNA expression of LFABP in treatments containing 12% roasted full-fat soybean and extruded full-fat soybean was higher than the control (p<0.01).

Conclusion: The results showed improvement of performance by including roasted or extruded soybean in broiler diets. The mRNA level of LFABP would be increased by increasing the full-fat soybean levels. [5]

Reference

[1] Hyson, D., Rutledge, J.C. and Berglund, L., 2003. Postprandial lipemia and cardiovascular disease. Current atherosclerosis reports, 5(6), pp.437-444.

[2] Musso, G., Gambino, R., De Michieli, F., Cassader, M., Rizzetto, M., Durazzo, M., Fagà, E., Silli, B. and Pagano, G., 2003. Dietary habits and their relations to insulin resistance and postprandial lipemia in nonalcoholic steatohepatitis. Hepatology, 37(4), pp.909-916.

[3] Havel, R.J., Kane, J.P. and Kashyap, M.L., 1973. Interchange of apolipoproteins between chylomicrons and high density lipoproteins during alimentary lipemia in man. The Journal of clinical investigation, 52(1), pp.32-38.

[4] Djellouli, F., Krouf, D., Lacaille-Dubois, M. A. and Bouchenak, M. (2018) “Portulaca oleracea Reduces Lipemia, Glycemia, and Oxidative Stress in Streptozotocin-induced Diabetic Rats Fed Cholesterol-enriched Dietq”, Journal of Pharmaceutical Research International, 23(4), pp. 1-12. doi: 10.9734/JPRI/2018/43495.

[5] Vakili, R. (2014) “Performance of Brioler Chickens and mRNA Expression of Liver Fatty Acid Binding Protein Gene Fed with Soybean”, Annual Research & Review in Biology, 4(13), pp. 2163-2173. doi: 10.9734/ARRB/2014/8781.

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