Dietary whey hydrolysate with exercise alters the plasma protein profile: a comprehensive protein analysis.

OBJECTIVE: It has been shown that dietary whey protein accelerates glucose uptake by altering glycoregulatory enzyme activity in skeletal muscle. In the present study, we investigated the effect of dietary whey protein on endurance and glycogen resynthesis and attempted to identify plasma proteins that reflected the physical condition by a comprehensive proteomics approach. METHODS: Male c57BL/6 mice were divided into four groups: sedentary, sedentary with whey protein hydrolysate, exercise, and exercise with whey protein hydrolysate. The mice in the exercise groups performed treadmill running exercise five times per week for 4 wk. Protein profiling of plasma sample obtained from individuals was performed, as were measurements of endurance performance and the glycogen content of gastrocnemius muscle. RESULTS: After the training period, the endurance of mice fed the whey diet was improved compared with that of mice fed the control diet. Muscle glycogen content was significantly increased after 4 wk of exercise, and intake of whey protein led to a further increase in glycogen. Apolipoproteins A-II and C-I and ß(2)-glycoprotein-1 were found to be altered by training combined with the intake of whey protein, without significant changes induced by exercise or whey protein alone. CONCLUSION: Results of the present study suggest that these three proteins may be potential biomarkers of improved endurance and glycogen resynthesis and part of the mechanism that mediates the benefits of whey protein.

Administration of a PPARalpha agonist increases serum apolipoprotein A-V levels and the apolipoprotein A-V/apolipoprotein C-III ratio.

Apolipoprotein A-V (apoA-V) first gained attention as a regulator of triglycerides through transgenic mouse studies. Furthermore, peroxisome proliferator-activated receptor alpha (PPARalpha) agonists such as fenofibrate increase apoA-V mRNA expression. Our group recently developed the first assay to quantitate serum apoA-V levels. Therefore, we sought to determine whether administration of a PPARalpha agonist would increase circulating apoA-V. Cynomolgus monkeys were dosed for 14 days with 0.3 mg/kg/day LY570977 L-lysine, a potent and selective PPARalpha agonist. Blood samples were drawn throughout the treatment period and after a 2 week washout. Administration of the PPARalpha agonist caused a 50% decrease in triglycerides that reversed at washout. Serum apoA-V concentrations increased 2-fold, correlated inversely with triglycerides, and were reversible at washout. The apoA-V/apoC-III ratio increased >2-fold, with this increase also reversible at washout. These data demonstrate for the first time that a PPARalpha agonist increases circulating apoA-V protein levels and the apoA-V/apoC-III ratio.

Polyunsaturated fatty acids interact with the PPARA-L162V polymorphism to affect plasma triglyceride and apolipoprotein C-III concentrations in the Framingham Heart Study.

Peroxisome proliferator-activated receptor alpha (PPARalpha) is a nuclear transcription factor regulating multiple genes involved in lipid metabolism. It was shown that a common leucine to valine (L162V) substitution at the PPARalpha gene (PPARA) is functional and affects transactivation activity of PPARalpha ligands, such as PUFA, on a concentration-dependent basis. The current study examined this gene-nutrient interaction in relation to plasma lipid variables in a population-based study consisting of 1003 men and 1103 women participating in the Framingham cohort and consuming their habitual diets. We found significant gene-nutrient interactions between the L162V polymorphism and total PUFA intake, which modulated plasma triglycerides (TG; P < 0.05) and apolipoprotein C-III (apoC-III; P < 0.05) concentrations. The 162V allele was associated with greater TG and apoC-III concentrations only in subjects consuming a low-PUFA diet (below the population mean, 6% of energy). However, when PUFA intake was high, carriers of the 162V allele had lower apoC-III concentrations. This interaction was significant even when PUFA intake was considered as a continuous variable (P = 0.031 for TG and P < 0.001 for apoC-III), suggesting a strong dose-response effect. When PUFA intake was <4%, 162V allele carriers had approximately 28% higher plasma TG than did 162L homozygotes (P < 0.01). Conversely, when PUFA intake was >8%, plasma TG in 162V allele carriers was 4% lower than in 162L homozygotes. Similar results were obtained for (n-6) and (n-3) fatty acids. Our data show that the effect of the L162V polymorphism on plasma TG and apoC-III concentrations depends on the dietary PUFA, with a high intake triggering lower TG in carriers of the 162V allele.

Circulating triacylglycerol and apoE levels in response to EPA and docosahexaenoic acid supplementation in adult human subjects.

High doses of n-3 PUFA found in fish oils can reduce the circulating concentration of triacylglycerol (TG), which may contribute to the positive impact of these fatty acids on the risk of CVD. The present study aimed to establish the differential impact of EPA and docosahexaenoic (DHA) on plasma lipids and apo in adults. Forty-two normolipidaemic adult subjects completed a double-blind placebo controlled parallel study, receiving an EPA-rich oil (4.8 g EPA/d), DHA-rich oil (4.9 g DHA/d) or olive oil as control, for a period of 4 weeks. No effects of treatment on total cholesterol, LDL-cholesterol or HDL-cholesterol were evident. There was a significant 22 % reduction in TG level relative to the control value following the DHA treatment (P=0.032), with the 15 % decrease in the EPA group failing to reach significance (P=0.258). There were no significant inter-group differences in response to treatment for plasma apoA1, -C3 or -E levels, although a significant 15 % within-group increase in apoE was evident in the EPA (P=0.006) and DHA (P=0.003) groups. In addition, a within-group decrease in the apoA1:HDL-cholesterol ratio was observed in the DHA group, suggesting a positive impact of DHA on HDL particle size. The DHA intervention resulted in a significant increase in the proportion of EPA P=0.000 and DHA P=0.000 in plasma phospholipids, whilst significant increases in EPA P=0.000 and docosapentaenoic acid P=0.002, but not DHA P=0.193, were evident following EPA supplementation (P<0.05). Our present results indicate that DHA may be more efficacious than EPA in improving the plasma lipid profile.

Fenofibrate improves the atherogenic lipid profile and enhances LDL resistance to oxidation in HIV-positive adults.

BACKGROUND: Low HDL-cholesterol, hypertriglyceridemia (HTG) and occurrence of small dense LDL could be involved in increased cardiovascular risk in HIV-infected patients. This study evaluates the effects of fenofibrate and/or Vitamin E on lipoprotein profile. DESIGN: Thirty-six HIV-positive adults with fasting triglycerides (TGs) > or =2 mmol/l and stable antiretroviral therapy (ART) were randomly assigned to receive either micronised fenofibrate (200 mg/day) or Vitamin E (500 mg/day) for a first period of 3 months and the association of both for an additional 3-month period. METHODS AND RESULTS: Total cholesterol, HDL-C, LDL-C, triglycerides, apoA1, apoB, apoCIII, lipoprotein composition, LDL size and LDL resistance to copper-induced oxidation were determined before initiation of fenofibrate or Vitamin E, and 3 and 6 months thereafter. Three months of fenofibrate treatment results in a significant decrease in triglycerides (-40%), apoCIII (-21%), total cholesterol (-14%), apoB (-17%) levels, non-HDL-C (-17%), TG/apoA1 ratio in HDL (-27%) associated with an increase in HDL-C (+15%) and apoA1 (+11%) levels. Moreover, fenofibrate increases LDL size and enhances LDL resistance to oxidation. Three months of Vitamin E supplementation only improves LDL resistance to oxidation and addition to fenofibrate results in a slightly greater effect. CONCLUSION: Fenofibrate therapy improves the atherogenic lipid profile in HIV-positive adults with hypertriglyceridemia.

Prediction of PPAR-alpha ligand-mediated physiological changes using gene expression profiles.

Peroxisome proliferator-activated receptor (PPAR)-alpha controls the transcription of a variety of genes involved in lipid metabolism and is the target receptor for the hypolipidemic drug class of fibrates. In the present study, the molecular and physiological effects of seven different PPAR-activating drugs have been examined in a rodent model of dyslipidemia. The drugs examined were selected to display varying potencies and efficacies toward PPAR-alpha. To help elucidate the link between the gene regulation elicited by PPAR-alpha ligands and the concomitant physiological changes, we have used cDNA microarray analysis to identify smaller gene sets that are predictive of the function of these ligands. A number of genes showed strong correlations to the relative PPAR-alpha efficacy of the drugs. Furthermore, using multivariate analysis, a strong relationship between the drug-induced triglyceride lowering and the transcriptional profiles of the different drugs could be found.

Effect of feeding diets of varying fatty acid composition on apolipoprotein expression in newborn swine.

The purpose of this study was to determine the effect of chronic (1 wk) feeding of dietary triacylglycerol (TG) of varying fatty acid composition on small intestinal and hepatic apolipoprotein expression, as well as serum lipid and apolipoprotein concentrations, in newborn swine. Two-day-old female swine were fed one of three diets by gavage with the following lipid composition: medium-chain TG (MCT; MCT oil), intermediate-chain saturated TG (ICST; coconut oil), and long-chain polyunsaturated TG (LCPUT; safflower oil) at 753 kJ . kg-1 . day-1 with 51% of energy from fat. After 1 wk, serum lipids and apolipoprotein concentrations were measured, and jejunal apolipoprotein B (apo B) and apo A-I mass and apo B, apo A-I, apo A-IV, and apo C-III synthesis were measured. Liver was processed for determination of apo B and apo A-I mass and apo B, apo A-I, apo C-III, and beta-actin mRNA abundance by slot blot hybridization. Compared with the MCT and LCPUT groups, the ICST group had higher total serum cholesterol, TG, high-density lipoprotein (HDL)-cholesterol, and apo A-I concentrations. There were no differences among the three groups for intestinal apolipoprotein mass or synthesis. In liver, apo A-I mass was highest in the ICST group. Liver apo A-I and apo C-III mRNA abundance was highest in the ICST group. Among all three groups, hepatic apo A-I mass correlated significantly with plasma HDL-cholesterol concentrations, and serum TG concentrations correlated with hepatic apo C-III mRNA abundance. In conclusion, we found that in the newborn piglet, chronic feeding of ICST increases serum total cholesterol, TG, HDL-cholesterol, and apo A-I concentrations and hepatic expression of apo A-I and apo C-III mRNA, compared with feeding of MCT or LCPUT. We speculate that increased hepatic apo A-I expression may contribute to the higher serum HDL and apo A-I concentrations in the ICST animals. Increased hepatic expression of apo C-III with ICST feeding may contribute to the higher serum TG concentrations by apo C-III-mediated inhibition of the catabolism of triacylglycerol-rich lipoproteins.

Hypobetalipoproteinemia associated with apo B-48.4, a truncated protein only 14 amino acids longer than apo B-48.

Familial hypobetalipoproteinemia is an autosomal codominant trait that can be caused by mutations in the apo B gene. Here we report a novel apo B gene mutation causing hypobetalipoproteinemia, that is associated with the synthesis of a truncated apo B protein in a young healthy male subject and his mother. The mutation is an A deletion at position 6627 of the apo B cDNA leading to a truncated protein of 2166 amino acids (apo B-48.4). This truncated apo B was detected mainly in VLDL, LDL and in trace amounts in HDL, but not in the lipoprotein deficient plasma fraction. Affected family members present with elevated levels of HDL-cholesterol, mainly due to an increase in HDL2 particles. Postprandial triglycerides and retinyl esters in the d < 1.006 g/ml lipoprotein in the proband showed a normal response to an oral fat load compared to a group of eight matched healthy controls. In summary this novel mutation is associated with hypobetalipoproteinemia with a normal fat absorption as expected for a protein with a length similar to that of apo B-48.

Identification, characterization, cloning, and expression of apolipoprotein C-IV, a novel sialoglycoprotein of rabbit plasma lipoproteins.

We have identified and characterized a novel proline- and arginine-rich protein component of lipoproteins, present in up to five sialylated isoforms, in rabbit blood plasma. The pI of the desialylated protein is 5.7. Based upon its N-terminal sequence, a complete cDNA sequence of 555 nucleotides was cloned from rabbit liver. The synthesized protein is predicted to contain 124 amino acids, including a typical signal peptide of 27 residues. The mature protein of 97 amino acids, designated apolipoprotein C-IV, is associated with the lipoproteins of blood plasma, primarily very low density and high density lipoproteins. It contains two potential amphipathic helices characteristic of plasma apolipoproteins and forms discoidal micelles with phosphatidylcholine. Northern analysis shows a single 0.6-kilobase apolipoprotein C-IV mRNA, detected only in the liver, and Southern analysis suggests a single copy gene. Sialylated apolipoprotein C-IV is secreted from transfected mammalian cells. Nucleotide sequence comparisons demonstrate a strong homology to portions of the upstream regions of the mouse and human apolipoprotein C2 genes, within each of which a distinct gene has recently been identified. The nucleotide sequences and the predicted amino acid sequences, as well as corresponding cDNA sequences in the rat and monkey, indicate that the apolipoprotein C4 gene has been highly conserved during mammalian evolution.

Postprandial lipoprotein(a) response to a single meal containing either saturated or omega-3 polyunsaturated fatty acids in subjects with hypoalphalipoproteinemia.

We have recently reported that the apolipoprotein (apo) B-100-apo(a) complex, the protein moiety of lipoprotein(a) [Lp(a)], has a high affinity for triglyceride(TG)-rich particles (TRP) and that this complex can affiliate with endogenous TG-rich lipoproteins. To shed more light on the apo B-100-apo(a) complex associated with plasma TRP during postprandial lipidemia, we fed five male subjects presenting with primary hypoalphalipoproteinemia (HP) and four male controls a single fat meal (60 g/m2) containing saturated fatty acids (SFA) and, 6 weeks later, an isocaloric meal containing omega-3 polyunsaturated fatty acids. The subjects were phenotyped for plasma Lp(a) and apo C-III levels, apo(a) and apo E isoforms, and lipoprotein lipase and hepatic lipase activities. Vitamin A was included in the meal as a marker of intestinally derived TRP. Following the SFA meal, three of the HP subjects showed a decrease in plasma levels of Lp(a) that lasted 10 to 12 hours in the presence of an increased hypertriglyceridemic response. Two HP subjects who had low preprandial lipoprotein lipase activity and elevated plasma apo C-III levels showed an increase in plasma Lp(a) levels along with the hypertriglyceridemic excursion. However, in all cases, inclusive of the controls, there was an elevation in plasma levels of TRP of Sf greater than 1,000 that contained apo B-100-apo(a) 6 to 8 hours after the meal. This TRP excursion appeared not to be related to the basal levels of plasma Lp(a), high-density lipoprotein (HDL) cholesterol, TGs, or apo(a) and apo E isoforms, and it did not coincide with the retinyl ester peak.(ABSTRACT TRUNCATED AT 250 WORDS)

Multivitamin supplementation of adult omnivores and lactovegetarians: circulating levels of vitamin A, D and E, lipids, apolipoproteins and selenium.

Serum levels of fat-soluble vitamins, lipids, apolipoproteins, total protein, hemoglobin, iron, and selenium were determined in healthy Finnish adults during a 7-month period beginning in January and ending in August. The subjects were either omnivores or established lactovegetarians, who had consumed their respective diets for at least 6 months prior to the study. Half of the subjects in both groups received daily multivitamin supplementation and the other half served as controls. In the beginning, the lactovegetarians differed from the omnivores in having lower serum levels of protein, apolipoproteins A-I and C-II, and higher levels of standardized alpha-tocopherol. During the study, serum retinol and standardized alpha-tocopherol (in March and May), as well as apolipoproteins A-I and C-II, and selenium decreased in the omnivores and 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, cholesterol, HDL-cholesterol, and the HDL-cholesterol/cholesterol ratio increased. Apolipoprotein B decreased and then increased. In the lactovegetarians, serum selenium and protein decreased during the study, whereas retinol and alpha-tocopherol stayed higher than in the omnivores. Consumption of the lactovegetarian diet was accompanied by lower circulating levels of cholesterol and selenium and higher levels of retinol and standardized alpha-tocopherol than the mixed diet. Multivitamin supplementation may have value especially for omnivores in northern countries, like Finland, in providing better retinol, alpha-tocopherol, vitamin D, and selenium status in late winter and early spring.

Quantification of plasma lipids and apolipoproteins in British Halflop rabbits. A comparison between normocholesterolemic rabbits, hypercholesterolemic rabbits (modified WHHL rabbits) and rabbits fed an atherogenic diet.

We have established isolation methods and developed electroimmunoassays for rabbit apolipoprotein A-I (apo A-I), apo B, apo C-III and apo E. The assays were used to characterize a hyperlipidemic strain of the British Halflop rabbits (BHL rabbits), obtained after cross-breeding with WHHL rabbits and referred to as modified WHHL rabbits, and to investigate the changes in the apolipoprotein levels induced by feeding normal BHL rabbits an atherogenic diet (0.25% cholesterol and 3% coconut oil). The modified WHHL rabbits were characterized by increased levels of apo B, apo C-III and apo E as well as cholesterol, phospholipids and triacylglycerol as compared to chow-fed BHL rabbits, while the apo A-I levels were only half of those found in the chow-fed animals. The modified WHHL rabbits had virtually no low density lipoprotein (LDL) receptor activity and a low fractional catabolic rate (FCR) of LDL. These results indicate that the modified WHHL rabbit has the homozygous form of the LDL receptor deficiency. The BHL rabbits fed the atherogenic diet showed increased levels of cholesterol, triacylglycerol, apo B, apo C-III and apo E, as compared to those of the chow-fed BHL rabbits. The apo E and apo C-III reached levels in the range of or even higher than those of the modified WHHL rabbits. The apo A-I levels on the other hand did not differ from those of the chow-fed rabbits. Feeding an atherogenic diet led to a decrease in the FCR of LDL to a level similar to that found in the modified WHHL rabbits.

Serum selenium is related to low-density lipoproteins in healthy children but not in children with diabetes.

The serum concentrations of selenium in 13 healthy children and 27 children with type 1 diabetes mellitus were evaluated in relation to serum lipoprotein and apolipoprotein concentrations. In healthy children a correlation was found between serum selenium and both serum cholesterol (r = 0.56; p less than 0.05) and serum triglycerides (r = 0.56; less than 0.05) and their low-density lipoprotein (LDL) + very low-density lipoprotein (VLDL) fractions (r = 0.60 and 0.56 respectively; p less than 0.05), but not their high-density lipoprotein fractions. Associations were also found between selenium and apolipoproteins, especially A II and C II (r = 0.57; p less than 0.05). In diabetic children serum selenium was significantly correlated with apolipoproteins A II and Apo C II, but not with any lipoprotein or lipid or any of their fractions. This study supports the hypothesis that serum selenium is an integral part of the defence system against degradation products associated with LDL and VLDL in young healthy humans. These associations were not found in diabetes, which might suggest that the defence system against lipid peroxidation is less effective in this disease.

Postprandial distribution of apolipoproteins C-II and C-III in normal subjects and patients with mild hypertriglyceridemia: comparison of meals containing corn oil and medium-chain triglyceride oil.

Five healthy male subjects and five patients with mild hypertriglyceridemia were studied following the administration of 800-kcal liquid meals containing 40% of energy from fat, 40% from carbohydrate, and 20% from protein. On the first day of the study, the fat source was corn oil (long-chain triglyceride), whereas medium-chain triglyceride (MCT) oil was used the second day. Meals were infused into the duodenum using a peristaltic pump. Plasma samples, obtained at hourly intervals for 8 hours, were analyzed for glucose, cholesterol, triglyceride, and apolipoproteins C-II and C-III. The distribution of apoC-II and apoC-III between ultracentrifugally-separated triglyceride-rich lipoproteins (TRL) and high-density lipoproteins (HDL) was also evaluated. The patient group had significantly elevated fasting levels of triglyceride, apoC-II and apoC-III, as well as much greater lipemic response to the meal containing corn oil. In both groups, TRL apoC-II and apoC-III levels were positively correlated with the triglyceride level as it increased following the corn oil meal. These correlations were also observed in the normal subjects when the MCT oil meal was administered, even though changes in plasma triglycerides were minimal. In normal subjects, whole plasma levels of apoC-II and apoC-III decreased significantly following the meal containing corn oil, whereas no net changes occurred following the MCT oil meal. In hypertriglyceridemic subjects, small decreases in plasma apoC-II and apoC-III levels occurred after both meals, although the changes in apoC-II were not statistically significant. The tendency for decreased plasma apoC levels following alimentary lipemia confirms previous reports, and provides further data to support the concept that some apoC is cleared from plasma in association with TRL remnants. The finding that mildly hypertriglyceridemic subjects responded similarly to both conventional fat and MCT may indicate that their rates of remnant clearance were similar following the two meals.