Magnitude of alimentary lipemia is related to intima-media thickness of the common carotid artery in middle-aged men

Food Intake Suppresses ApoB Secretion and Fractional Catabolic Rates in Humans

BACKGROUND

Humans spend much of the day in the postprandial state. However, most research and clinical guidelines on plasma lipids pertain to blood drawn after a 12-hour fast. We aimed to study the metabolic differences of apoB lipoproteins between the fasting and postprandial states.

METHODS

We investigated plasma apoB metabolism using stable isotope tracers in 12 adult volunteers under fasting and continuous postprandial conditions in a randomized crossover study. We determined the metabolism of apoB in multiple lipoprotein subfractions, including light and dense VLDLs (very-low-density lipoproteins), IDLs (intermediate-density lipoproteins), and light and dense LDLs (low-density lipoproteins) that do or do not contain apoE or apoC3.

RESULTS

A major feature of the postprandial state is 50% lower secretion rate of triglyceride-rich lipoproteins and concurrent slowdown of their catabolism in circulation, as shown by 34% to 55% lower rate constants for the metabolic pathways of conversion by lipolysis from larger to smaller lipoproteins and direct clearance of lipoproteins from the circulation. In addition, the secretion pattern of apoB lipoprotein phenotypes was shifted from particles containing apoE and apoC3 in the fasting state to those without either protein in the postprandial state.

CONCLUSIONS

Overall, during the fasting state, hepatic apoB lipoprotein metabolism is activated, characterized by increased production, transport, and clearance. After food intake, endogenous apoB lipoprotein metabolism is globally reduced as appropriate to balance dietary input to maintain the supply of energy to peripheral tissues.

Salsalate Improves Postprandial Glycemic and Some Lipid Responses in Persons With Tetraplegia: A Randomized Clinical Pilot Trial With Crossover Design

Objectives

To investigate the effects of salsalate on fasting and postprandial (PP) glycemic, lipidemic, and inflammatory responses in persons with tetraplegia.

Methods

This study was a randomized, double-blind, cross-over design. It was conducted at a university laboratory. Ten males aged 25 to 50 years with SCI at C5-8 levels for ≥1 year underwent 1 month of placebo and salsalate (4 g/day) treatment. Blood samples were drawn before and 4 hours after breakfast and lunch fast-food meal consumption.

Results

Descriptive statistics indicate that fasting and PP glucose values were reduced with salsalate (pre-post mean difference, 4 ± 5 mg/dL and 8 ± 8 mg/dL, respectively) but largely unchanged with placebo (0 ± 6 mg/dL and -0 ± 7 mg/dL, respectively). Insulin responses were generally reciprocal to glucose, however less pronounced. Fasting free fatty acids were significantly reduced with salsalate (191 ± 216 mg/dL, p = .021) but not placebo (-46 ± 116 mg/dL, p = .878). Results for triglycerides were similar (25 ± 34 mg/dL, p =.045, and 7 ± 29 mg/dL, p = .464). Fasting low-density lipoprotein (LDL) levels were higher after salsalate (-10 ± 12 mg/dL, p = .025) but not placebo (2 ± 9 mg/dL, p = .403) treatment. Inflammatory markers were largely unchanged.

Conclusion

In this pilot trial, descriptive values indicate that salsalate decreased fasting and PP glucose response to fast-food meal challenge at regular intervals in persons with tetraplegia. Positive effects were also seen for some lipid but not for inflammatory response markers. Given the relatively "healthy" metabolic profiles of the participants, it is possible that salsalate's effects may be greater and more consistent in people with less favorable metabolic milieus.

Adipose tissue expression of UCP1 and PRDM16 genes and their association with postprandial triglyceride metabolism and glucose intolerance

AIMS

UCP1 and PRDM16 genes, primarily involved in browning of adipose tissue that can affect lipid metabolism are also associated with diabetes risk. Therefore, we planned to study the adipose tissue expression of UCP1 and PRDM 16 genes in subjects with glucose intolerance to find out its association with postprandial triglyceride (PPTg) measures and T2DM.

METHODS

A total of 30 subjects were recruited in three groups i.e., NGT, prediabetes and T2DM (NDDM + known T2DM) who were matched for age, sex and BMI. An 8-hour standardized fat challenge test was performed to study lipemic responses. UCP1 and PRDM16 genes quantification in adipose tissue was performed by real-time PCR followed by SDS PAGE.

RESULTS

UCP1 gene expression in SAT was significantly lower in T2DM and prediabetes as compared to NGT group while PRDM16 gene expression was significantly lower in T2DM group as compared to NGT group. UCP1 gene expression correlated with PPTg measures as well as with glycaemic measures while PRDM16 gene expression correlated with glycaemic measures only.

CONCLUSION

This study found downregulation of PRDM16 and UCP1 gene expression in SAT in subjects with glucose intolerance. The association of UCP1 gene expression with PPTg dysmetabolism may contribute to greater predisposition to T2DM.

Postprandial endothelial dysfunction and CIMT after oral fat challenge in patients with type 2 diabetes mellitus with and without macrovascular disease - A preliminary study

BACKGROUND

Very few studies have reported on association of postprandial lipids and endothelial dysfunction among patients with diabetes. Whether endothelial dysfunction particularly postprandial FMD is worse in patients with T2DM with macrovascular disease compared to those without and whether this difference is related to postprandial hypertriglyceridemia (PPHTg) is unclear. Therefore, present study was aimed to assess the relationship between PPHTg and endothelial function in patients with T2DM with and without macrovascular disease.

METHOD

Endothelial dysfunction by FMD and CIMT were compared in patients with T2DM with and without macrovascular disease (n = 13 each group) and 13 age, sex and BMI matched healthy individuals after an oral fat challenge.

RESULTS

There was significant postprandial deterioration of FMD 4-hr after fat challenge in patients with diabetes (P < 0.001) as well as healthy individuals (P = 0.004). Patients with diabetes with macrovascular disease had significantly lower fasting (5.7 ± 6.1% vs. 22.7 ± 10.0% and vs. 24.7 ± 5.3%) as well as postprandial (4-hr) (3.1 ± 5.0% vs. 15.3 ± 8.1% and vs. 15.4 ± 5.7%) FMD compared to other two groups. Fasting, postprandial as well as change in FMD and CIMT in patients with diabetes correlated significantly with fasting as well as postprandial triglycerides with stronger correlation in those with macrovascular disease.

CONCLUSION

Study found significant endothelial dysfunction by FMD that shows substantial further deterioration postprandially following high fat meal in patients with diabetes with macrovascular disease compared to patients with diabetes without macrovascular disease and healthy individuals. Study also indicates that PPHTg is a contributor to endothelial dysfunction. However, more studies are required to corroborate these findings.

Effect of postprandial triglycerides on DDT/ppDDE levels in subjects with varying degree of glucose intolerance

BACKGROUND

Organochlorine pesticides such as DDT as well as postprandial hypertriglyceridemia have been linked with insulin resistance and diabetes mellitus. The cardiometabolic risk of PPhTg could also be due to its potential to increase the serum levels of this highly lipophilic pesticide. We studied the effect of postprandial triglyceride responses to a standard oral fat challenge on the levels of DDT and its metabolites in subjects with varying degree of glucose intolerance METHODS: A standard fat challenge was performed in 60 subjects who were categorized as NGT, prediabetes, and NDDM based on an earlier OGTT. Fasting and postprandial levels of serum triglycerides, plasma DDT and its metabolites were estimated and compared in the 3 groups and their association with each other, and measures of glycemia and insulin resistance were also determined.

RESULTS

Peak Tg and TgAUC levels were significantly higher in NDDM group as compared to NGT and PD groups. TgAUC showed positive correlation with fasting plasma glucose (r=0.33, p=0.01), postprandial plasma glucose (r=0.39, p=0.002) and HOMA IR(r=0.63, p=0.001). ppDDE levels were found to be significantly higher in NDDM subjects compared with NGT group. ppDDE-AUC was significantly higher in the NDDM group compared with the other two study groups. Mean ppDDE levels also showed strong positive correlation with peak Tg (r=0.295 p=0.022), TgAUC (r=0.303 p=0.018), iPPTgAUC(r=0.57 p≤0.001) and iPPpeakTg(r=0.51 p≤0.001) as well as with FPG (r=0.269 p=0.038) PPPG (r=0.424 p=0.001) and HbA1c (r=0.321 p=0.012).

CONCLUSION

The findings of this study support the concept that the cardiometabolic risk associated with PPhTg may at least in part be related to the associated increase in serum levels of lipophilic OCPs like DDT.

VIIaAT complexes, procoagulant phospholipids, and thrombin generation during postprandial lipemia

INTRODUCTION

Factor VII activation occurs postprandially. A proportion of activated factor VII (VIIa) circulates in complex with antithrombin (VIIaAT). Our primary objective was to assess the effects of postprandial lipemia on circulating VIIaAT, procoagulant phospholipid (PPL) activity, and thrombin generation.

METHODS

Plasma samples from postmyocardial infarction patients (n = 40) and controls (n = 39) were taken before and at 3 and 6 hours during a standardized oral fat tolerance test (OFTT). Fasting PPL activity measurements were also made in a second cohort of 108 postinfarction patients and 109 controls. VIIaAT was analyzed with the Asserachrom VIIaAT ELISA, PPL activity with the STA-Procoag-PPL kit, and thrombin generation with calibrated automated thrombogram with PRP-Reagent as trigger (all Diagnostica Stago products).

RESULTS

Postprandially, VIIaAT increased in all samples without significant case-control differences in the overall response during the OFTT. Thrombin generation measures peak height and velocity, and PPL activity, were marginally affected by the test meal in the controls. Levels of all patient baseline measures were significantly different from controls, indicating a more hypercoagulable state, and these differences were maintained throughout the OFTT. Fasting samples from cases showed higher PPL activity than control samples.

CONCLUSION

Viewing VIIaAT quantitation as a surrogate for TF activity measurement, postprandial increase in VIIaAT may reflect a mechanism that adds to the cardiovascular risk associated with postprandial lipemia. On the other hand, the impact of postprandial lipemia on PPL activity and thrombin generation seems to be minor.

Association between carotid intima-media thickness and fasting blood glucose level: A population-based cross-sectional study among low-income adults in rural China

Aims/Introduction

Carotid intima‐media thickness (CIMT) is an established predictor of cardiovascular disease and stroke. We aimed to identify the association between CIMT and blood glucose, as well as the risk factors associated with increased CIMT in a low‐income Chinese population.

Materials and Methods

Stroke‐free and cardiovascular disease‐free residents aged ≥45 years were recruited. B‐mode ultrasonography was carried out to measure CIMT.

Results

There were 2,643 participants (71.0%) in the normal group, 549 (14.7%) in the impaired fasting glucose group and 533 (14.3%) in the diabetes mellitus group. The determinants of increased CIMT were older age; male sex; low education; hypertension; smoking; high levels of systolic blood pressure, fasting blood glucose and low‐density lipoprotein cholesterol; and low levels of diastolic blood pressure, triglycerides and high‐density lipoprotein cholesterol, after adjusting for covariates. Age and hypertension were the common risk factors for increased CIMT in all three groups. Furthermore, male sex, smoking and high low‐density lipoprotein cholesterol level were positively associated with the mean CIMT in the normal group; high triglycerides levels were negatively associated with the mean CIMT in the impaired fasting glucose group; and alcohol consumption was an independent risk factor for mean CIMT in the diabetes mellitus group. Hypertension was the greatest risk factor for increased CIMT.

Conclusions

These findings suggest that it is crucial to manage and control traditional risk factors in low‐income populations in China in order to decelerate the recent dramatic increase in stroke incidence, and to reduce the burden of stroke.

Hypertriglyceridemia and Cardiovascular Outcomes

Cardiovascular disease, particularly ischemic heart disease, is one of the most common causes of morbidity and mortality in the United States. Atherosclerosis, the root cause of ischemic heart disease, is promoted by risk factors like elevated plasma low-density lipoprotein, low plasma high-density lipoprotein, smoking, hypertension, and diabetes mellitus. Even 66 years after a relation between triglycerides (TG) and cardiovascular disease was first suspected, TGs still continue to be a controversial risk factor and target for therapy. Some previous studies did not show any significant positive relationship between TG and cardiovascular mortality; however, recent meta-analyses found otherwise. The role of elevated TG in patients with low low-density lipoprotein and interventions to lower TG to reduce cardiovascular mortality and morbidity is an area of active research.

Genetic variation of the intestinal fatty acid-binding protein 2 gene in carotid atherosclerosis

The alanine (A) to threonine (T) substitution at codon 54 of the intestinal fatty acid-binding protein 2 (FABP2) has been associated with dyslipidaemia and other characteristics of the metabolic syndrome, which in turn is a risk factor for cerebrovascular disease. The aim of this study was to investigate whether the A54T polymorphism in the FABP2 gene is associated with internal carotid artery (ICA) stenosis in stroke patients. Swedish subjects initially diagnosed with acute cerebrovascular disease (n = 196) that had been assessed with ultrasound of the carotid arteries were identified and grouped depending on whether a stenosis was found. The subjects were genotyped for the A54T polymorphism using a PCR-RFLP method. In a multivariate logistic-regression analysis, where known risk factors for atherosclerosis were fixed (diabetes, systolic blood pressure, age and smoking), having the FABP2 T allele was a significant risk factor for ICA stenosis (odds ratio 2.9; 95% confidence interval, 1.1-7.7; p = 0.04) together with diabetes (odds ratio 4.9; 95% confidence interval, 1.8-14; p < 0.01). Age, smoking and blood pressure did not reach statistical significance. In conclusion, our result supports the hypothesis that the FABP2 A54T polymorphism is associated with ICA stenosis.

The Physiological Regulation of Skeletal Muscle Fatty Acid Supply and Oxidation During Moderate-Intensity Exercise

Energy substrates that are important to the working muscle at moderate intensities are the non-esterified fatty acids (NEFAs) taken up from the circulation and NEFAs originating from lipolysis of the intramuscular triacylglycerol (IMTAG). Moreover, NEFA from lipolysis via lipoprotein lipase (LPL) in the muscle of the very-low-density lipoproteins and in the (semi) post-prandial state chylomicrons may also contribute. In this review, the NEFA fluxes and oxidation by skeletal muscle during prolonged moderate-intensity exercise are described in terms of the integration of physiological systems. Steps involved in the regulation of the active muscle NEFA uptake include (1) increased energy demand; (2) delivery of NEFA to the muscle; (3) transport of NEFA into the muscle by NEFA transporters; and (4) activation of the NEFAs and either oxidation or re-esterification into IMTAG. The increased metabolic demand of the exercising muscle is the main driving force for all physiological regulatory processes. It elicits functional hyperemia, increasing the recruitment of capillaries and muscle blood flow resulting in increased NEFA delivery and accessibility to NEFA transporters and LPL. It also releases epinephrine that augments adipose tissue NEFA release and thereby NEFA delivery to the active muscle. Moreover, NEFA transporters translocate to the plasma membrane, further increasing the NEFA uptake. The majority of the NEFAs taken up by the active muscle is oxidized and a minor portion is re-esterified to IMTAG. Net IMTAG lipolysis occurs; however, the IMTAG contribution to total fat oxidation is rather limited compared to plasma-derived NEFA oxidation, suggesting a complex role and regulation of IMTAG utilization.

Desaturation index versus isotopically measured de novo lipogenesis as an indicator of acute systemic lipogenesis

BACKGROUND

High carbohydrate feeding is known to increase plasma triglycerides as well as hepatic de novo lipogenesis (DNL) and may be implicated in the development of hepatic insulin resistance and fatty liver. Unfortunately, it is technically challenging to determine what proportion of circulating plasma triglycerides have been derived from the newly synthesized fatty acids in the postprandial period. The aims of this study were to 1) characterize the changes in the plasma postprandial total fatty acid pool in beagles following the consumption of meals containing 44% (Control) and 74% (High Sucrose) carbohydrate and 2) determine if changes in plasma fatty acid concentration and delta-9 desaturation index (DI) would be useful as simple and easy to measure biomarkers of systemic DNL.

FINDINGS

No differences in plasma total palmitic acid (16:0), stearic acid (18:0) and oleic acid (18:1) concentrations or delta-9 DI for the total 18:0 and 18:1 pools between High Sucrose and Controls were observed. However, newly synthesized 16:0 (2.6 ± 0.2% vs. 8.8 ± 2.0%; p = 0.016), 18:0 (0.93 ± 0.2% vs. 4.1 ± 1.7%; p = 0.007) and 18:1 (0.29 ± 0.09% vs. 3.5 ± 1.2%; p = 0.017) were higher in High Sucrose versus Control animals, respectively. Also, the delta-9 DI for the newly synthesized 18:0 and 18:1 pools was higher at 2 and 6 hours postprandial, with a pattern of change which supports the increased stearoyl-CoA desaturase (SCD-1) activity following high carbohydrate feeding followed by a down regulation of this enzyme.

CONCLUSIONS

Our data show that high sucrose meals increase the relative contribution of systemic DNL produced fatty acids to the total postprandial plasma fatty acid pool. These data also show that a different pattern of both fatty acid synthesis and disposal occurs depending on energy and macronutrient profile of the meal. These changes are in spite of no observable changes in the plasma concentrations or ratios of the total fatty acid pool opposed to the observed changes in the newly synthesized fatty acid pool.

Peripheral arterial disease, type 2 diabetes and postprandial lipidaemia: Is there a link?

Peripheral arterial disease, manifested as intermittent claudication or critical ischaemia, or identified by an ankle/brachial index < 0.9, is present in at least one in every four patients with type 2 diabetes mellitus. Several reasons exist for peripheral arterial disease in diabetes. In addition to hyperglycaemia, smoking and hypertension, the dyslipidaemia that accompanies type 2 diabetes and is characterised by increased triglyceride levels and reduced high-density lipoprotein cholesterol concentrations also seems to contribute to this association. Recent years have witnessed an increased interest in postprandial lipidaemia, as a result of various prospective studies showing that non-fasting triglycerides predict the onset of arteriosclerotic cardiovascular disease better than fasting measurements do. Additionally, the use of certain specific postprandial particle markers, such as apolipoprotein B-48, makes it easier and more simple to approach the postprandial phenomenon. Despite this, only a few studies have evaluated the role of postprandial triglycerides in the development of peripheral arterial disease and type 2 diabetes. The purpose of this review is to examine the epidemiology and risk factors of peripheral arterial disease in type 2 diabetes, focusing on the role of postprandial triglycerides and particles.

Postprandial lipemia as a cardiometabolic risk factor

High levels of fasting circulating triglycerides (TG) represent an independent risk factor for cardiovascular disease. In western countries, however, people spend most time in postprandial conditions, with continuous fluctuation of lipemia due to increased levels of TG-rich lipoproteins (TRLs), including chylomicrons (CM), very low density lipoproteins (VLDL), and their remnants. Several factors contribute to postprandial lipid metabolism, including dietary, physiological, pathological and genetic factors. The presence of coronary heart disease, type 2 diabetes, insulin resistance and obesity is associated with higher postprandial TG levels compared with healthy conditions; this association is present also in subjects with normal fasting TG levels. Increasing evidence indicates that impaired metabolism of postprandial lipoproteins contributes to the pathogenesis of coronary artery disease, suggesting that lifestyle modifications as well as pharmacological approaches aimed at reducing postprandial TG levels might help to decrease the cardiovascular risk.

The effect of insulin resistance on postprandial triglycerides in Korean type 2 diabetic patients

We hypothesized that the influence of metabolic parameters depends on metabolic syndrome (MetS) status. The clinical and metabolic implications of postprandial triglyceride (ppTG) in Korean type 2 diabetes were investigated in the presence or absence of MetS, MetS+, or MetS-. To investigate the relationship between ppTG and metabolic parameters, we analyzed plasma TG levels in 126 newly diagnosed, drug-naïve diabetic patients after ingestion of a standardized low calorie and fat (500 kcal, 17.5 g fat) liquid meal formula. We report that MetS+ patients have significantly higher BMI, waist/hip ratio, HOMA-IR, and HOMA-β, but insignificantly higher fasting TG, ppTG, and ΔTG than MetS- patients. In the MetS+ patients, ppTG correlated with fasting TG and non-HDL, but was not related to HOMA-IR. In MetS- patients, ppTG correlated with fasting TG, non-HDL, blood pressure, waist/hip ratio, fasting C-peptide and insulin levels, and HOMA-IR. Multivariate analysis showed HOMA-IR to be a predictive factor for ppTG in MetS- patients but not in MetS+ patients. ppTG correlated with IR in MetS- type 2 diabetic patients but not in MetS+. This unexpected result implies that MetS+ diabetic patients already have high fasting TG and that IR influences fasting TG more dominantly than ppTG.

Association between postprandial triglycerides and coronary artery disease detected by coronary computed tomography angiography

BACKGROUND

Studies have demonstrated the association of severe anatomical coronary artery disease (CAD) with postprandial triglycerides (TG) concentrations. Nevertheless the relationship between less severe atherosclerosis plaque burden and postprandial TG is less established.

OBJECTIVE

to study the relationship between postprandial TG and CAD detected by coronary computed tomographic angiography (CTA).

MATERIAL AND METHODS

130 patients who underwent an oral fat tolerance test were enrolled (85 with CAD detected by CTA and 45 without). Postprandial lipemia was studied by measuring TG from T0h to T6h with 2-h intervals, and analyzed the TG change over time using a longitudinal multivariable linear mixed effects model with the log normal of the TG as the primary outcome.

RESULTS

The majority of individuals with CAD had non-obstructive disease (63.3%) Patients with CAD had a slower clearance of postprandial TG change from 4 h to 6 h (p<0.05) compared to patients without CAD. These results remained significant after adjustment for fasting TG and glucose, age, gender, body mass index, and waist circumference. However, those differences did not reach statistical significance after adjustment for fasting HDL-C.

CONCLUSION

Patients with mild (<25% lumen obstruction) and moderate CAD (25-50% lumen obstruction) detected by coronary CTA had an impaired postprandial metabolism, with a delayed TG clearance, when compared to individuals with no CAD. This difference was partially explained by the lower HDL-C. Thus, though postprandial TG may contribute to the development of CAD, this association is partially related to low HDL-C.

Postprandial lipemia in pre- and postmenopausal women

Background and Objective:

The increased risk for coronary artery disease observed in postmenopausal (PoW) women is partly explained by a more atherogenic lipoprotein profile. Moreover, natural menopause has been associated with an altered postprandial lipid profile. This study was designed to test the hypothesis that young premenopausal (PrW) and PoW may be independently associated with postprandial lipemia and indirectly associated with atherosclerosis.

Patients and Methods:

A total of 46 healthy PrW and 44 healthy PoW participated in a 5-h intervention study. Blood samples were taken at the baseline and at 1, 2, 3, and 4 h after eating. Total cholesterol, LDL-cholesterol, HDL-cholesterol, fasting, and postprandial triglycerides (PPTG) were determined sequentially in blood samples.

Results:

PPTG presented significant higher values in PoW compared to PrW (P < 0.05), but other lipids did not significantly differ between groups. PPTG concentrations in PoW were significantly higher than in PrW (P < 0.05). There was a significant time influence (P < 0.05) in TG in PrW and PoW, while time to peak and peak concentration were significantly higher in PoW than PrW. Other lipids were also decreased more in PrW than PoW, but not significantly so. Cholesterol concentrations showed a significant reduction after 2 h, to reach values similar to the baseline after 4 h in PrW but not in PoW. HDL-cholesterol concentration was decreased more in PoW compared to PrW but it was not significant.

Conclusions:

Lipid postprandial response indicates a higher cardiovascular risk pattern in PoW compared to PrW.

Association of postalimentary lipemia with atherosclerotic manifestations

We identified different lipemic and metabolic responses after the ingestion of a standardized meal by healthy adults and related them to atherosclerotic markers. Samples from 60 normolipidemic adults were collected before and after a liquid meal (40 g fat/m² body surface) at 0, 2, 4, 6, and 8 h for measurements of lipids, free fatty acids (FFA), insulin, cholesteryl ester transfer protein (CETP), autoantibodies to epitopes of oxidized LDL (oxLDL Ab), lipolytic activities, and apolipoprotein E polymorphism. Mean carotid intima-media thickness (cIMT) was determined by Doppler ultrasound. The volunteers were classified into early (N = 39) and late (N = 31) triacylglycerol (TAG) responders to the test meal. Late responders showed lower HDL cholesterol concentration at fasting and in the TAG peak, lower insulin and higher FFA concentrations compared to early responders. Multivariate regression analyses showed that mean cIMT was associated with gender (male) and age in early responders and by cholesterol levels at the 6th hour in late responders. oxLDL Ab were explained by lipoprotein lipase and negatively by hepatic lipase and oxLDL Ab (fasting period) by CETP (negative) and FFA (positive). This study is the first to identify a postalimentary insulin resistance state, combined with a reduced CETP response exclusively among late responders, and the identification of the regulators of postalimentary atherogenicity. Further research is required to determine the metabolic mechanisms described in the different postalimentary phenotypes observed in this study, as well as in different pathological states, as currently investigated in our laboratory.

Postprandial lipemia is not increased in patients with previous unprovoked venous thromboembolism

BACKGROUND

Patients with arterial cardiovascular disease have increased postprandial lipemia, and plasma levels of postprandial remnants are related to the progression of atherosclerosis. Studies have shown that patients with unprovoked venous thromboembolism have increased risk of arterial cardiovascular disease.

OBJECTIVE

To investigate whether patients with a history of unprovoked venous thromboembolism have increased postprandial lipemia.

METHODS

A population-based case-control study was performed in 20 patients with a history of unprovoked venous thromboembolism and 20 age- and gender-matched healthy controls. Participants were subjected to a standard fat tolerance test (1 g/kilo body weight) with subsequent blood sampling every second hour for 8 hours. Lipids were measured by traditional methods and lipoprotein subclasses by proton nuclear magnetic resonance.

RESULTS

Fasting lipids and lipoprotein subclasses did not differ between groups. The postprandial lipemia, assessed by the incremental area under the triglyceride curve, was not different in venous thromboembolism patients and healthy controls (5.0 ± 3.6 mmol/L∗h vs 5.3 ± 4.4 mmol/L∗h, P = .81). Similarly, the distribution and size of the lipoprotein subclasses obtained 4 hours postprandially did not differ between groups.

CONCLUSION

Patients with a history of unprovoked venous thromboembolism had similar lipoprotein subclasses size, distribution, and postprandial lipemia as healthy controls. Our findings indicate that postprandial lipemia is not a link between unprovoked venous thromboembolism and arterial cardiovascular disease.

Postprandial Triglyceride Is Associated with Fasting Triglyceride and HOMA-IR in Korean Subjects with Type 2 Diabetes

BACKGROUND

Recent studies indicate postprandial triglyceride (TG) had a better association with cardiovascular events and metabolic syndrome than fasting TG. The authors of the present study investigated the metabolic and clinical relevance of postprandial TG.

METHODS

In a cross-sectional retrospective study, the authors of the present study compared fasting and postprandial TG and analyzed the relationship between postprandial TG and various demographic and metabolic parameters in 639 Korean subjects with type 2 diabetes (T2D, group I, n=539) and impaired fasting glucose (IFG, group II, n=100) after ingestion of a standardized liquid meal (total 500 kcal, 17.5 g fat, 68.5 g carbohydrate, and 17.5 g protein).

RESULTS

Fasting and postprandial TG were significantly correlated (r=0.973, r=0.937, P<0.001) in group I and II, respectively. Of the variables, total cholesterol, waist circumference and body mass index were significantly correlated with fasting and postprandial TG in both groups. Only postprandial TG showed a significant correlation with glucose metabolic parameters (e.g., postprandial glucose, homeostatic model assessment of insulin resistance [HOMA-IR], and fasting C-peptide) in subjects with T2D. Multiple regression analysis showed fasting TG and HOMA-IR could be predictable variables for postprandial TG in subjects with T2D.

CONCLUSION

Postprandial TG was very strongly correlated with fasting TG. The authors of the present study suggest insulin resistance may be more associated with postprandial TG than fasting TG in Korean T2D patients on a low-fat diet.

Serum apolipoprotein B-48 levels are correlated with carotid intima-media thickness in subjects with normal serum triglyceride levels

BACKGROUND

Postprandial hyperlipidemia (PPHL) is an independent risk factor for coronary heart disease (CHD) which is based on the accumulation of chylomicrons (CM) and CM remnants containing apolipoprotein B-48 (apoB-48). Since atherosclerotic cardiovascular diseases are frequently observed even in subjects with normal serum triglyceride (TG) level, the correlation between fasting apoB-48 containing lipoproteins and carotid intima-media thickness (IMT) was analyzed in subjects with normal TG levels.

METHODS

From subjects who took their annual health check at the Osaka Police Hospital (n=245, male), one-hundred and sixty-four male subjects were selected to take part in this study; the excluding factors were: systolic blood pressure ≥ 140 mmHg, intake of antihypertensive or antihyperlipidemic drugs, or age >65 years. The association between biochemical markers and IMT was analyzed and independent predictors of max-IMT were determined by multiple regression analysis in all subjects and in groups N-1 (TG<100mg/dl, n=58), N-2 (100 ≤ TG<150 mg/dl, n=53) and H (150 ≤ TG mg/dl, n=53), respectively.

RESULTS

Fasting total cholesterol, LDL-cholesterol, HDL-cholesterol, apoB-100 and lnRemL-C (remnant lipoprotein-cholesterol) levels were not correlated with max-IMT, but lnTG and lnapoB-48 were significantly correlated with max-IMT in all subjects. LnapoB-48 and apoB-48/TG ratio were significantly correlated with max-IMT in group N-2. By multiple regression analysis, age and lnapoB-48 were independent variables associated with max-IMT in group N-2.

CONCLUSION

Serum apoB-48 level might be a good marker for the detection of early atherosclerosis in middle-aged subjects with normal-range levels of blood pressure and TG.

Is the beneficial effect of prior exercise on postprandial lipaemia partly due to redistribution of blood flow?

Preprandial aerobic exercise lowers postprandial lipaemia (a risk factor for coronary heart disease); however, the mechanisms responsible are still not clear. The present study investigated whether blood flow to skeletal muscle and/or the liver was increased in the postprandial period after exercise, relative to a control trial, and whether this resulted from increased cardiac output or redistribution of flow. Eight overweight inactive males, aged 49.4±10.5 years (mean±S.D.), acted as their own controls in a counterbalanced design, either walking briskly for 90 min at 60% V̇O2max (maximal oxygen uptake), or resting in the lab, on the evening of day 1. The following morning, a fasting blood sample was collected, participants consumed a high-fat breakfast, and further venous blood samples were drawn hourly for 6 h. Immediately after blood sampling, Doppler ultrasound was used to measure cardiac output and blood flow through both the femoral artery of one leg and the hepatic portal vein, with the ultrasonographer blinded to trial order. The total postprandial triacylglycerol response was 22% lower after exercise (P=0.001). Blood flow through the femoral artery and the hepatic portal vein was increased by 19% (P<0.001) and 16% (P=0.033), respectively, during the 6-h postprandial period following exercise; however, postprandial cardiac output did not differ between trials (P=0.065). Redistribution of blood flow, to both exercised skeletal muscle and the liver, may therefore play a role in reducing the plasma triacylglycerol response to a high-fat meal on the day after an exercise bout.

Is the effect of prior exercise on postprandial lipaemia the same for a moderate-fat meal as it is for a high-fat meal?

Moderate-intensity exercise can lower the TAG response to a high-fat meal; however, the British diet is moderate in fat, and no study to date has compared the effect of such exercise on responses to high-fat and moderate-fat meals. The present work investigated the effect of brisk walking performed 13 h before intake of both high-fat and moderate-fat meals on postprandial plasma TAG concentrations. Eight inactive, overweight men completed four separate 2 d trials, i.e. rest (Con) or a 90-min treadmill walk (Ex) on the evening of day 1, followed by the ingestion of a moderate-fat (Mod) or high-fat (High) meal on the morning of day 2. High-fat meals contained 66 % of total energy as fat, while the percentage was 35 % for moderate-fat meals; both the meals were, however, isoenergetic. On day 2, venous blood was sampled in the fasted state, 30 and 60 min after ingesting the test meal and then hourly until 6 h post-meal. Exercise reduced plasma TAG concentrations significantly (P < 0·001), with no exercise × meal interaction (P = 0·459). Walking reduced the total TAG response to a high-fat meal by 29 % (relative to High Con); the same bout of exercise performed before ingesting a moderate-fat meal lowered total TAG by 26 % (compared with Mod Con). The ability of a single moderate-intensity aerobic exercise bout to lower postprandial TAG concentrations is just as great, in percentage terms, when the test meal ingested is of a moderate rather than a high fat content.

Dyslipidaemia in the metabolic syndrome and type 2 diabetes: pathogenesis, priorities, pharmacotherapies

IMPORTANCE OF THE FIELD

Dyslipoproteinaemia is a cardinal feature of the metabolic syndrome that accelerates atherosclerosis. It is usually characterized by high plasma concentrations of triglyceride-rich and apolipoprotein B (apoB)-containing lipoproteins, with depressed concentrations of high-density lipoprotein (HDL). Drug interventions are essential for normalizing metabolic dyslipidaemia.

AREAS COVERED IN THIS REVIEW

This review discusses the mechanisms and treatment for dyslipidaemia in the metabolic syndrome and type 2 diabetes.

WHAT THE READER WILL GAIN

A comprehensive understanding of the pathophysiology and pharmacotherapy of dyslipidaemia in the metabolic syndrome and diabetes.

TAKE HOME MESSAGE

Dysregulation of lipoprotein metabolism may be due to a combination of overproduction of triglyceride-rich lipoproteins, decreased catabolism of apoB-containing particles, and increased catabolism of HDL particles. These abnormalities may be consequent on a global metabolic effect of insulin resistance and an excess of both visceral and hepatic fat. Lifestyle modifications may favourably alter lipoprotein transport in the metabolic syndrome. Patients with dyslipidaemia and established cardiovascular disease should receive a statin as first-line therapy. Combination with other lipid-regulating agents, such as ezetimibe, fibrates, niacins and fish oils may optimize the benefit of statin on atherogenic dyslipidaemia.

Genetic effects on postprandial variations of inflammatory markers in healthy individuals

Circulating levels of inflammatory markers predict the risk of cardiovascular disease (CVD), mediated perhaps in part by dietary fat intake, through mechanisms only partially understood. To evaluate post-fat load changes in inflammatory markers and genetic influences on these changes, we administered a standardized high-fat meal to 838 related Amish subjects as part of the Heredity and Phenotype Intervention (HAPI) Heart Study and measured a panel of inflammatory markers, including C-reactive protein (CRP), interleukin-1beta (IL-1beta), matrix metalloproteinase-1 and -9 (MMP-1 and MMP-9), and white blood cell (WBC) count, before and 4 h after fat challenge (CRP prechallenge only). Heritabilities (h(2) +/- s.d.) of basal inflammatory levels ranged from 16 +/- 8% for MMP-9 (P = 0.02) to 90 +/- 7% for MMP-1 (P < 0.0001). Post-fat load, circulating levels of WBC, MMP-1, and MMP-9 increased by 16, 32, and 43% (all P < 0.0001), with no significant changes in IL-1beta. Postprandial changes over the 4-h period were modestly heritable for WBC (age- and sex-adjusted h(2) = 14 +/- 9%, P = 0.04), but the larger MMP-1 and MMP-9 changes appeared to be independent of additive genetic effects. These results reveal that a high-fat meal induces a considerable inflammatory response. Genetic factors appear to play a significant role influencing basal inflammatory levels but to have minimal influence on post-fat intake inflammatory changes.

Postprandial apolipoprotein B48 is associated with asymptomatic peripheral arterial disease: a study in patients with type 2 diabetes and controls

BACKGROUND

Postprandial hyperlipidemia is a common feature in type 2 diabetes; our aim was to investigate whether there is an association between subclinical peripheral arterial disease (PAD) and the levels of apolipoprotein B48, as a specific marker for postprandial lipidemia.

METHODS

We enrolled 101 patients with type 2 diabetes and 73 controls free from clinical cardiovascular disease. Main outcome measures were the presence of subclinical PAD, assessed by the ankle-brachial index, and the intestinal particles measured as the concentration of apolipoprotein B48 at fasting and 4h after a mixed breakfast.

RESULTS

No control had subclinical PAD. Of the 101 diabetic patients, 21 had subclinical PAD. The levels of apo B48, both fasting and postprandial, were only significantly raised in the diabetic patients who had PAD. The diabetic patients without vascular disease had similar concentrations of triglycerides and apo B48 to the controls. In binary logistic regression analyses, only smoking and postprandial B48 levels, in addition to diabetes, were independently associated with PAD. On the other hand, PAD but not diabetes was associated with the fasting and postprandial levels of apo B48.

CONCLUSION

Our study suggests that apolipoprotein B48 levels might be a marker of occult PAD in patients suffering from type 2 diabetes mellitus. Accordingly, subclinical PAD should be taken into account in studies on postprandial lipidemia involving patients with diabetes.

Endothelial progenitor cells in vascular health: focus on lifestyle

Endothelial dysfunction, which is considered the functional equivalent of a disrupted balance between endothelial injury and repair, precedes overt atherosclerosis by many years. Although this phenomenon is part of the normal aging process, prevention of early and progressive endothelial dysfunction has become an important therapeutic target. Evidence has accumulated to show that endothelial progenitor cells (EPC), contribute substantially to preservation of a structurally and functionally intact endothelium. There has been considerable progress in our understanding of the various cell types that were in the past all covered by the term "EPC." EPC home to sites of endothelial injury and ischemia, where they proliferate, differentiate and integrate into the endothelial layer or exert a paracrine function by producing vascular growth factors. Although more emphasis has been put on the pharmacological approach of endothelial dysfunction, the effect of a healthy lifestyle, via mobilization and functional improvement of EPC, is increasingly recognized. This review will focus on successful lifestyle interventions that aim to maintain vascular health through beneficial actions on cell populations with vasculogenic potential ("EPC"). The role of physical activity and dietary recommendations, which are considered essential elements of a healthy lifestyle, will be particularly emphasized. A thorough understanding of the physiology of endothelial benefits, derived from such interventions, may help to implement these measures on top of classical drug therapy, but also provides a solid basis for primary prevention. The effects of additional elements of a comprehensive lifestyle advice, such as smoking cessation, weight and stress reduction, also comprise a modulation of EPC function and circulating numbers and are therefore included in this review as well.

Docosahexaenoic acid (DHA) and cardiovascular disease risk factors

Numerous epidemiological and controlled interventional trials have supported the health benefits of long-chain omega-3 fatty acids in the form of docosahexaenoic acid (DHA, 22:6n-3) plus eicosapentaenoic acid (EPA, 20:5n-3) from fish and fish oils as well as from algal sources. The beneficial effects on cardiovascular disease and related mortality including various risk factors for cardiovascular disease (particularly lowering circulating triglyceride levels and the triglyceride:HDL-cholesterol ratio) have been observed in the absence of any concomitant blood cholesterol lowering. With appropriate dosages, consistent reductions in both fasting and postprandial triglyceride levels and moderate increases in fasting HDL-cholesterol levels have been observed with algal DHA in the majority of trials. These results are similar to findings for fish oils containing DHA and EPA. Related to greater fish intake, higher levels of DHA in circulating blood biomarkers (such as serum phospholipid) have been associated with reduced risks for the progression of coronary atherosclerosis and lowered risk from sudden cardiac death. Controlled clinical trials have also indicated the potential for algal DHA supplementation to have moderate beneficial effects on other cardiovascular disease risk factors including blood pressures and resting heart rates. Recommended intakes of DHA+EPA from numerous international groups for the prevention and management of cardiovascular disease have been forthcoming, although most have not offered specific recommendations for the optimal individual intake of DHA and EPA.

Therapeutic effects of fibrates in postprandial lipemia

Hypertriglyceridemia is observed in many metabolic diseases such as the metabolic syndrome, diabetes mellitus, or mixed dyslipidemia frequently leading to premature coronary heart disease (CHD). Additionally, several studies have shown that postprandial hypertriglyceridemia is pronounced in patients with CHD, metabolic syndrome, hypertension, and other pathologic conditions. The triglyceride-rich lipoprotein remnants accumulating in the postprandial state seem to be involved in atherogenesis and in events leading to thrombosis. Since abnormal postprandial lipemia is associated with pathologic conditions, its treatment is of clinical importance.Fibrates are of significant help in managing hypertriglyceridemia. This review summarizes the effect of fibric acid derivatives on postprandial lipemia. Fibrates decrease the production of and enhance the catabolism of triglyceride-rich lipoproteins through the activation of peroxisome proliferator-activated receptor-alpha. Results of clinical studies with fibrates have confirmed their action in decreasing postprandial triglyceride levels by increasing lipoprotein lipase activity, decreasing apolipoprotein CIII production, and by increasing fatty acid oxidation in the liver.It is concluded that fibrates are effective agents in lowering the postprandial increase in remnant lipoprotein particles and retinyl palmitate. Furthermore, fibrates can also affect the postprandial lipid profile by increasing hepatic lipase levels and in some cases, by reducing cholesterol ester transfer protein activity. The main target of fibrate therapy is to improve fasting hypertriglyceridemia, which is an essential component associated with improving postprandial lipemia. Fibrates are well tolerated by patients and adverse effects have been reported rarely after their administration.

Association of serum apolipoprotein B48 level with the presence of carotid plaque in type 2 diabetes mellitus

AIMS

The atherogenicity of chylomicron remnants has been discussed. We examined whether serum apoB48 level is associated with the presence of carotid plaque in type 2 diabetic patients.

METHOD

Forty type 2 diabetic patients (21 males and 19 females, 52.8+/-11.8 years old; mean+/-S.D.) were divided into two groups by the presence or absence of carotid plaque. The diurnal change of serum apoB48 level was measured by enzyme-linked immunosorbent assay.

RESULTS

Fasting serum apoB48 level was higher in the subjects with carotid plaque than those without (6.5+/-3.8vs. 4.1+/-1.9 microg/ml, p=0.01). Age- and gender-adjusted analysis showed that the presence of carotid plaque was associated with fasting apoB48 (OR 1.43; 95% CI, 1.07-2.09, p=0.04) and triglyceride (OR 1.14; 95% CI, 1.02-1.32, p=0.04) levels. In normal LDL-cholesterol (<140 mg/dl) subjects, the presence of carotid plaque was associated with fasting apoB48 level (OR 2.16; 95% CI, 1.22-5.32, p=0.04), but not associated with fasting triglyceride level (OR 1.11; 95% CI, 0.99-1.30, p=0.13).

CONCLUSIONS

Serum apoB48 level was strongly associated with the presence of carotid plaque in type 2 diabetic patients.

Postprandial lipaemia in patients with impaired fasting glucose, impaired glucose tolerance and diabetes mellitus

AIMS

To compare the postprandial lipid responses in subjects with prediabetes (IFG and IGT), newly detected diabetes mellitus (NDDM) and normal glucose tolerance (NGT).

METHODS

Postprandial lipid responses to a standard oral fat challenge was studied in forty-four subjects who were divided after an OGTT into NGT, pure impaired fasting glucose (PIFG), pure impaired glucose tolerance (PIGT) and NDDM.

RESULTS

There was a significantly higher postprandial triglyceride (PPTg) response with a higher PPTg area under curve (p=0.004) and peak PPTg levels (p=0.003) in patients with NDDM but not with either PIFG (p>0.05) or PIGT (p>0.05) when compared with NGT. Overall, PPTg responses correlated significantly with fasting plasma glucose (p=0.001) and 2h plasma glucose (p=0.001) but not with age, sex, body mass index, waist, or insulin resistance.

CONCLUSION

Subjects with newly detected diabetes mellitus displayed postprandial hypertriglyceridemia after a standard oral fat meal challenge while no such abnormality could be demonstrated in subjects with IFG or IGT. This defect is probably related to glycemic status and insulin resistance.

Correlation of serum IGF-I and IGFBP-1 and -3 to cardiovascular risk indicators and early carotid atherosclerosis in healthy middle-aged men

OBJECTIVES

IGF-I, IGFBP-1 and IGFBP-3 are putative mediators in cardiovascular disease. The present study examined (i) the correlations of circulating IGF-I, IGFBP-1 and IGFBP-3 to established cardiovascular risk factors and signs of early atherosclerosis as reflected by ultrasound measurement of common carotid intima-media thickness (IMT), and (ii) whether serum concentrations of these analytes are modulated during alimentary lipaemia.

DESIGN

Cross-sectional clinical study.

PATIENTS

A biobank and clinical database based on 96 healthy Caucasian men, aged 50 years, with an apolipoprotein (apo) E3/E3 genotype, who had originally undergone investigations of postprandial lipoprotein metabolism was used for the study.

MEASUREMENTS

Total IGF-I, IGFBP-1 and IGFBP-3 were determined in serum by radioimmunoassay (RIA). Free IGF-I was measured by a commercial two-site immunoradiometric assay (IRMA).

RESULTS

In multivariate analyses, fasting serum free IGF-I correlated inversely with IMT and accounted for 5% of the variation in multiple R(2). When fasting serum IGFBP-1 was entered in the models instead of IGF-I, IGFBP-1 correlated positively with IMT and accounted for 6% of the variation in IMT. IGFBP-3 and total IGF-I were unrelated to IMT. There were no associations between free IGF-I and cardiovascular risk factors, whereas IGFBP-1 behaved like a component of the insulin resistance syndrome. Serum free IGF-I increased and IGFBP-1 decreased postprandially.

CONCLUSION

The data indicate that serum free IGF-I and IGFBP-1 are implicated in early atherosclerosis.

Dietary, physiological, genetic and pathological influences on postprandial lipid metabolism

Most of diurnal time is spent in a postprandial state due to successive meal intakes during the day. As long as the meals contain enough fat, a transient increase in triacylglycerolaemia and a change in lipoprotein pattern occurs. The extent and kinetics of such postprandial changes are highly variable and are modulated by numerous factors. This review focuses on factors affecting postprandial lipoprotein metabolism and genes, their variability and their relationship with intermediate phenotypes and risk of CHD. Postprandial lipoprotein metabolism is modulated by background dietary pattern as well as meal composition (fat amount and type, carbohydrate, protein, fibre, alcohol) and several lifestyle conditions (physical activity, tobacco use), physiological factors (age, gender, menopausal status) and pathological conditions (obesity, insulin resistance, diabetes mellitus). The roles of many genes have been explored in order to establish the possible implications of their variability in lipid metabolism and CHD risk. The postprandial lipid response has been shown to be modified by polymorphisms within the genes for apo A-I, A-IV, A-V, E, B, C-I and C-III, lipoprotein lipase, hepatic lipase, fatty acid binding and transport proteins, microsomal triglyceride transfer protein and scavenger receptor class B type I. Overall, the variability in postprandial response is important and complex, and the interactions between nutrients or dietary or meal compositions and gene variants need further investigation. The extent of present knowledge and needs for future studies are discussed in light of ongoing developments in nutrigenetics.

Removal of triacylglycerols from chylomicrons and VLDL by capillary beds: the basis of lipoprotein remnant formation

The triacylglycerol content of chylomicrons and VLDL (very-low-density lipoprotein) compete for the same lipolytic pathway in the capillary beds. Although chylomicron triacylglycerols appear to be the favoured substrate for lipoprotein lipase, VLDL particles compete in numbers. Methods to quantify the specific triacylglycerol removal from VLDL and chylomicrons may involve endogenous labelling of the triacylglycerol substrate with stable isotopes in combination with arteriovenous blood sampling in humans. Arteriovenous quantification of remnant lipoproteins suggests that adipose tissue with its high lipoprotein lipase activity is a principal site for generation of remnant lipoproteins. Under circumstances of reduced efficiency in the removal of triacylglycerols from lipoproteins, there is accumulation of remnant lipoproteins, which are potentially atherogenic.

Lipoprotein metabolism in chronic renal insufficiency

Chronic renal insufficiency (CRI) is associated with a characteristic dyslipidemia. Findings in children with CRI largely parallel those in adults. Moderate hypertriglyceridemia, increased triglyceride-rich lipoproteins (TRL) and reduced high-density lipoproteins (HDL) are the most usual findings, whereas total and low-density lipoprotein cholesterol (LDL-C) remain normal or modestly increased. Qualitative abnormalities in lipoproteins are common, including small dense LDL, oxidized LDL, and cholesterol-enriched TRL. Measures of lipoprotein lipase and hepatic lipase activity are reduced, and concentrations of apolipoprotein C-III are markedly elevated. Still an active area of research, major pathophysiological mechanisms leading to the dyslipidemia of CRI include insulin resistance and nonnephrotic proteinuria. Sources of variability in the severity of this dyslipidemia include the degree of renal impairment and the modality of dialysis. The benefits of maintaining normal body weight and physical activity extend to those with CRI. In addition to multiple hypolipidemic pharmaceuticals, fish oils are also effective as a triglyceride-lowering agent, and the phosphorous binding agent sevelamer also lowers LDL-C. Emerging classes of hypolipidemic agents and drugs affecting sensitivity to insulin may impact future treatment. Unfortunately, cardiovascular benefit has not been convincingly demonstrated by any trial designed to study adults or children with renal disease. Therefore, it is not possible at this time to endorse general recommendations for the use of any agent to treat dyslipidemia in children with chronic kidney disease.

Effect of a single high-fat meal on endothelial function in patients with the metabolic syndrome: role of tumor necrosis factor-alpha

BACKGROUND AND AIMS

A single high-fat meal may induce endothelial activation and dysfunction in both normal subjects and in patients with type 2 diabetes. The aim of this study was to assess the effect of a high-fat meal on endothelial function in patients with the metabolic syndrome.

METHODS AND RESULTS

Twenty-five patients with the metabolic syndrome (ATP III criteria) were matched for sex, age and body mass index with 25 subjects without the metabolic syndrome. All subjects ate under supervision a high fat meal (760 calories) with 59% energy from fat, 12% energy from protein and 29% energy from carbohydrates. Compared with the control group, subjects with the metabolic syndrome had reduced endothelial function, as assessed with the l-arginine test, and higher circulating levels of TNF-alpha. Following the high-fat meal, both triglyceride and TNF-alpha levels increased more in subjects with the metabolic syndrome than in subjects without, while endothelial function decreased more in subjects with the metabolic syndrome. There was a significant relation between increases in TNF-alpha levels and decreases in endothelial function score in subjects with the metabolic syndrome (r=-0.39, P=0.03).

CONCLUSION

TNF-alpha levels are increased in subjects with the metabolic syndrome; moreover, a high-fat meal produces further increase in its levels associated with endothelial dysfunction.

Methodology for studying postprandial lipid metabolism

BACKGROUND

Postprandial lipid metabolism in humans has deserved much attention during the last two decades. Although fasting lipid and lipoprotein parameters reflect body homeostasis to some extent, the transient lipid and lipoprotein accumulation that occurs in the circulation after a fat-containing meal highlights the individual capacity to handle an acute fat input. An exacerbated postprandial accumulation of triglyceride-rich lipoproteins in the circulation has been associated with an increased cardiovascular risk.

METHODS

The important number of studies published in this field raises the question of the methodology used for such postprandial studies, as reviewed.

RESULTS

Based on our experiences, the present review reports and discuss the numerous methodological issues involved to serve as a basis for further works. These aspects include aims of the postprandial tests, size and nutrient composition of the test meals and background diets, pre-test conditions, characteristics of subjects involved, timing of sampling, suitable markers of postprandial lipid metabolism and calculations.

CONCLUSION

In conclusion, we stress the need for standardization of postprandial tests.

A high-fat meal is accompanied by increased plasma interleukin-6 concentrations

BACKGROUND AND AIM

Enhanced and prolonged postprandial lipaemia is associated with coronary heart disease (CHD). However, the mechanisms linking postprandial lipaemia to the increased risk of atherosclerosis and CHD remain to be determined. The aim of the present study was to examine the effects of a high-fat meal on plasma levels of the pro-inflammatory cytokine interleukin-6 (IL-6) and cellular adhesion molecules in CHD patients and control subjects.

METHODS AND RESULTS

Forty-one middle-aged men with premature CHD and 26 healthy male controls were investigated. The plasma triglyceride response to the high-fat meal was significantly greater among cases than controls. The oral fat load induced a twofold increase in plasma concentrations of IL-6, an increase that was similar in CHD patients and control subjects. No changes could be detected in plasma concentrations of cellular adhesion molecules in response to postprandial lipaemia in either CHD patients or control subjects.

CONCLUSION

The results of the present study suggest that a high-fat meal affects mechanisms that induce increased inflammatory activity, which is recognised as a key modulator in the development of atherosclerosis and CHD. However, the increased levels of plasma IL-6 appear not to be determined by the magnitude of the postprandial triglyceridaemia.

Postprandial glucose and not triglyceride concentrations are associated with carotid intima media thickness in women with normal glucose metabolism: the Hoorn prandial study

The present study aimed to compare the associations of postprandial glucose (ppGL) and postprandial triglycerides (ppTG) with carotid intima media thickness (cIMT) in women with normal glucose metabolism (NGM) and type 2 diabetes (DM2). Post-menopausal women (76 with NGM, 78 with DM2), received two consecutive fat-rich and two consecutive carbohydrate-rich meals on separate occasions. Blood samples were taken before and 1, 2, 4, 6 and 8h following breakfast; lunch was given at t=4. Ultrasound imaging of the carotid artery was performed to measure cIMT. In women with NGM, an increase of 1.0 mmol/l glucose following the fat-rich meals was associated with a 50 microm cIMT increase (p=0.04), and following the carbohydrate meals, an increase of 1.8 mmol/l glucose was associated with a 50 microm larger cIMT (p=0.08). These associations were not explained by classical cardiovascular risk factors. However, no association between ppGL and cIMT was found in women with DM2 and ppTG were not associated with cIMT. The association between ppGL and cIMT in normoglycaemic women suggests that ppGL in the normal range is a marker or a risk factor for atherosclerosis. Postprandial glucose levels might be a better indicator of risk than post-OGTT glucose levels or triglyceride levels.

Comparison of low-fat meal and high-fat meal on postprandial lipemic response in non-obese men according to the -1131T>C polymorphism of the apolipoprotein A5 (APOA5) gene (randomized cross-over design)

OBJECTIVE

The purpose of this study was to compare low-fat (LF) meal and high-fat (HF) meal on the postprandial lipemic responses according to the -1131T>C polymorphism of the APOA5 gene in a population usually consuming a LF diet and having a high frequency of the variant allele at the APOA5 -1131T>C SNP.

METHODS

This study was conducted using a cross-over design and 49 non-obese healthy men (42.8 +/- 0.7 yrs, 23.9 +/- 0.25 kg/m(2)) participated in the meal tolerance test. They were randomly assigned to consume one of two types of experimental enteral formulae (LF vs HF) with a seven-day interval. Blood samples were collected at 0, 2, 3, 4 and 6h after ingestion and analyzed for total and chylomicron TG, glucose, insulin and free fatty acid.

RESULTS

No differences were found in anthropometic parameter, calorie and macronutrient intakes and total energy expenditure between TT (n = 23) and TC + CC (n = 26) men. Fasting total TG were higher in TC + CC men than TT men, but fasting chylomicron TG were not significantly different between TT men and C carriers, TT subjects had no significant differences in postprandial responses of total TG and chylomicron TG and postprandial mean changes of chylomicron TG between LF and HF meal. On the other hand, C carriers had delayed peak time of total TG compared to TT subject and higher postprandial response and mean changes of chylomicron TG at HF meal compared to LF meal.

CONCLUSION

The capacity to clear chylomicron-TG or hydrolyze TG might become a rate-limiting factor on HF diet in TC + CC men resulting in higher postprandial triglyceridemia. Therefore, HF diet for C carriers of the APOA5 gene may be one of important CVD risk factors.

Hyperglycaemia after glucose loading is a major predictor of preclinical atherosclerosis in nondiabetic subjects

OBJECTIVE

Carotid intima-media thickness (IMT) has proved to be an independent marker of preclinical atherosclerosis. The aim of this study was to determine whether carotid IMT is associated with the plasma glucose concentration in the fasting state, after loading with oral glucose, or with the insulin sensitivity index (ISI) in nondiabetic subjects with different levels of glucose intolerance and insulin resistance.

DESIGN

Cross-sectional study.

PATIENTS

A total of 160 nondiabetic subjects (147 from our obesity-overweight clinic and 13 healthy normal subjects) were included in the present study, among them 33 had normal glucose tolerance (NGT), 13 had impaired fasting glucose (IFG), 80 had impaired glucose tolerance (IGT) and 34 had both IFG and IGT.

MEASUREMENTS

Carotid IMT was assessed in the common carotid artery by a high-resolution B-mode ultrasound system. Plasma glucose was measured after fasting and at 30 min, 1, 2 and 3 h after a standard 75-g load of glucose. The ISI was calculated from the frequent sampling intravenous glucose tolerance test (FSIGT). Results The IMT values in the NGT group were lower than those in the IFG, IGT and IFG + IGT groups (P < 0.03). No statistical difference in IMT values was found among the latter three groups. Univariate correlation analyses showed that the IMT was positively associated with age, plasma glucose concentrations 1 and 2 h after glucose loading, and serum concentration of low density lipoprotein (LDL) cholesterol (r=0.39, 0.22, 0.25 and 0.18, respectively, P<0.05). Multiple regression analysis showed that only age, plasma glucose concentration 2 h after glucose loading, and LDL cholesterol appeared to be significant correlates of the IMT (P<0.0001), whereas the ISI was not.

CONCLUSIONS

In nondiabetic subjects with various degrees of glucose intolerance, there was a significant increase in IMT in those with IFG and IGT. Significant determinants of IMT, an indicator of preclinical atherosclerosis, include hyperglycaemia 2 h after a glucose load, age and LDL cholesterol, whereas fasting glucose concentration and the ISI were not significantly associated with IMT.

Association between postprandial remnant-like particle triglyceride (RLP-TG) levels and carotid intima-media thickness (IMT) in Japanese patients with type 2 diabetes: assessment by meal tolerance tests (MTT)

Our study evaluated the relationship between the pathologic changes associated with atherosclerosis, as primarily represented by postprandial remnant-like lipoproteins and carotid intima-media thickness (IMT), in type 2 diabetic patients. Meal tolerance tests (MTT) were performed in 68 patients with type 2 diabetes. The subjects were divided by pre-meal and 2-h postprandial triglyceride (TG) levels into the normotriglyceridemia (NTG) group; the postprandial hypertriglyceridemia (PHTG) group; and the fasting hypertriglyceridemia (FHTG) group. HOMA-R values were significantly higher in the FHTG group than in the NTG group, with the plasma pre-heparin LPL mass and serum adiponectin levels in the FHTG and PHTG groups significantly lower than in the NTG group. One- and two hour postprandial RLP-TG levels were significantly higher in the PHTG group than in the NTG group, while there was no significant difference in postprandial glucose levels between the two groups. The IMT values were significantly higher in both the FHTG and PHTG groups than in the NTG group. Logistics regression analysis of the 1- and 2-h RLP-TG values using IMT as an induced variable showed the odds ratio for high IMT values to be 5.17 (p < 0.05) for the 1-h RLP-TG values and 3.01 (p = 0.105) for the 2-h RLP-TG values. Our study results suggest that delayed TG metabolism leading to the retention of remnants in type 2 diabetic patients appears to be closely associated with atherosclerosis, and that postprandial hyperlipidemia is an independent risk factor for the early onset of atherosclerosis.

The apolipoprotein CI content of triglyceride-rich lipoproteins independently predicts early atherosclerosis in healthy middle-aged men

OBJECTIVES

In this study, we examined the apolipoprotein (apo) CI content of triglyceride-rich lipoproteins (TRLs) in relation to established coronary heart disease (CHD) risk factors and early atherosclerosis.

BACKGROUND

In Western society, the postprandial state constitutes a nearly constant stress on the vasculature and the metabolism of lipoproteins. Delayed clearance of postprandial TRL remnants has repeatedly been associated with premature CHD and may include the enrichment of these remnants with apoCI.

METHODS

We examined 72 healthy 50-year-old men with an apoE3/E3 genotype who had undergone an oral fat load test and B-mode ultrasound examination of the intima-media thickness (IMT) of the common carotid artery.

RESULTS

In the fasting state, plasma, very-low-density lipoprotein (VLDL), and low-density lipoprotein cholesterol, proinsulin, and apoB100-containing intermediate density lipoprotein levels were related to IMT (p < 0.05). In the postprandial state, IMT was related to triglycerides at 2 h (p < 0.01), large VLDL concentration at 3 h (p < 0.05), the apoCI plasma and TRL concentrations at 6 h (p < 0.05, p < 0.05), and the apoCI content of TRLs at 6 h (p < 0.002). Multivariate analysis revealed that the apoCI content of TRLs at 6 h (p < 0.0001), plasma triglyceride concentrations at 2 h (p < 0.006), and fasting plasma cholesterol concentration (p < 0.05) independently predicted IMT. In addition, the apoCI content of postprandial TRLs correlated strongly with the cholesterol content (r = 0.64, p < 0.0001).

CONCLUSIONS

Our results indicate that the apoCI content of postprandial TRLs is a novel independent risk factor for early atherosclerosis in normolipidemic healthy middle-aged men with possible implication for the enrichment of TRL remnant lipoproteins with cholesterol.