Endothelium-dependent vasodilation is related to the fatty acid composition of serum lipids in healthy subjects

LDL-c/HDL-c Ratio and NADPH-Oxidase-2-Derived Oxidative Stress as Main Determinants of Microvascular Endothelial Function in Morbidly Obese Subjects

The identification of obese subjects at higher risk for cardiovascular disease (CVD) is required. We aimed to characterize determinants of endothelial dysfunction, the initial step to CVD, in small omental arteries of visceral fat from obese subjects. The influences of analytical parameters and vascular oxidative stress mediated by NADPH-oxidase-2 (NOX2) on endothelial function were determined. Specimens were obtained from 51 obese subjects undergoing bariatric surgery and 14 non-obese subjects undergoing abdominal surgery. Obese subjects displayed reduced endothelial vasodilation to bradykinin (BK). Endothelial vasodilation (pEC50 for BK) among obese subjects was significantly and negatively associated with low-density lipoprotein cholesterol (LDL-c)/high-density lipoprotein cholesterol (HDL-c) ratio (r = -0.510, p = 0.0001) in both women and men, while other metabolic parameters and comorbidities failed to predict endothelial function. The vascular expression of NOX2 was upregulated in obese subjects and was related to decreased endothelial vasodilation (r = -0.529, p = 0.0006, n = 38) and increased oxidative stress (r = 0.783, p = 0.0044, n = 11) in arterial segments. High LDL-c/HDL-c (>2) and high NOX2 (above median) were independently associated with reduced endothelial function, but the presence of both conditions was related to a further impairment. Concomitant elevated LDL-c/HDL-c ratio and high vascular expression of NOX2 would exacerbate endothelial impairment in obesity and could reveal a deleterious profile for cardiovascular outcomes among obese subjects.

Consumption of red, white, and processed meat and odds of developing kidney damage and diabetic nephropathy (DN) in women: a case control study

Diabetic nephropathy (DN) is one of the most prevalent and severe complications of diabetes mellitus (DM) and is associated with increased morbidity and mortality. We aimed to investigate the associations between red, processed, and white meat consumption and the odds of developing kidney damage and DN in women. We enrolled 105 eligible women with DN and 105 controls (30-65 years). A validated and reliable food frequency questionnaire (FFQ) was used to evaluate the consumption of red, processed, and white meat. Biochemical variables and anthropometric measurements were assessed for all patients using pre-defined protocols. Binary logistic regression was conducted to examine possible associations. The results of the present study showed that there was a direct significant association between high consumption of red meat and processed meats and odds of microalbuminuria (red meat 2.30, 95% CI 1.25, 4.22; P-value = 0.007, processed meat: OR 2.16, 95% CI 1.18, 3.95; P-value = 0.01), severe albuminuria (red meat OR 3.25, 95% CI 1.38, 7.46; P-value = 0.007, processed meat: OR 2.35, 95% CI 1.01, 5.49; P-value = 0.04), BUN levels (red meat: OR 2.56, 95% CI 1.10, 5.93; P-value = 0.02, processed meat: OR 2.42, 95% CI 1.04, 5.62; P-value = 0.03), and DN (red meat 2.53, 95% CI 1.45, 4.42; P-value = 0.001, processed meat: OR 2.21; 95% CI 1.27, 3.85; P-value = 0.005). In summary, our study suggests that higher consumption of red and processed meat sources may be associated with microalbuminuria, severe albuminuria, higher BUN level, and higher odds of DN.

Postprandial lipid and vascular responses following consumption of a commercially-relevant interesterified palmitic acid-rich spread in comparison to functionally-equivalent non-interesterified spread and spreadable butter: a randomised controlled trial in healthy adults

Background: Interesterification is an industrial processing technique used widely where hard fats are essential for functionality and consumer acceptability, e.g. margarines and lower fat spreads. Objective: The aim of this study was to compare acute cardiovascular effects of functionally equivalent spreads (similar solid fat content) made with interesterified (IE) or non-IE palm-based fats, or spreadable butter. Methods: A randomised, controlled, 4-armed crossover, double-blind study (25 men, 25 women; 35-75 years; healthy; mean BMI 24.5, SD 3.8), compared effects of mixed nutrient meals containing 50 g fat from functionally equivalent products [IE spread, non-IE spread and spreadable butter (SB), with rapeseed oil (RO) as a reference treatment: with 16.7%, 27.9%, 19.3% and 4% palmitic acid, respectively] on 8 h postprandial changes in plasma triacylglycerol (TAG) and endothelial dysfunction (flow-mediated dilatation; FMD). Circulating reactive oxygen species (estimated using a neutrophil oxidative burst assay), glucose, insulin, NEFA, lipoprotein particle profiles, inflammatory markers (glycoprotein acetylation (Glyc-A) and IL-6), and biomarkers of endotoxemia were measured. Results: Postprandial plasma TAG concentrations after test meals were similar. However following RO versus the 3 spreads, there were significantly higher postprandial apolipoprotein B concentrations, and small HDL and LDL particle concentrations, and lower postprandial extra-large, large, and medium HDL particle concentrations, as well as smaller average HDL and LDL particle sizes. There were no differences following IE compared to the other spreads. Postprandial FMD% did not decrease after high-fat test meals, and there were no differences between treatments. Postprandial serum IL-6 increased similarly after test meals, but RO provoked a greater increase in postprandial concentrations of glycoprotein acetyls (GlycA), as well as 8 h sCD14, an endotoxemia marker. All other postprandial outcomes were not different between treatments. Conclusions: In healthy adults, a commercially-available IE-based spread did not evoke a different postprandial triacylglycerol, lipoprotein subclass, oxidative stress, inflammatory or endotoxemic response to functionally-equivalent, but compositionally-distinct alternative spreads. Clinical trial registry number: NCT03438084 (https://ClinicalTrials.gov).

Associations of the serum n-6 PUFA with exercise cardiac power in men

Low intake or tissue concentrations of the n-6 PUFA, especially to the major n-6 PUFA linoleic acid (LA), and low exercise cardiac power (ECP) are both associated with CVD risk. However, associations of the n-6 PUFA with ECP are unknown. The aim of the present study was to explore cross-sectional associations of the serum total n-6 PUFA, LA, arachidonic acid (AA), γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA) concentrations with ECP and its components. In total, 1685 men aged 42-60 years from the Kuopio Ischaemic Heart Disease Risk Factor Study and free of CVD were included. ANCOVA was used to examine the mean values of ECP (maximal oxygen uptake (VO2max)/maximal systolic blood pressure (SBP)) and its components in quartiles of the serum total and individual n-6 PUFA concentrations. After multivariable adjustments, higher serum total n-6 PUFA concentration was associated with higher ECP and VO2max (for ECP, the extreme-quartile difference was 0·77 ml/mmHg (95 % CI 0·38, 1·16, Pfor trend across quartiles < 0·001) and for VO2max 157 ml/min (95 % CI 85, 230, Pfor trend < 0·001), but not with maximal SBP. Similar associations were observed with serum LA concentration. Higher serum AA concentration was associated with higher ECP but not with VO2max or maximal SBP. The minor serum n-6 PUFA GLA and DGLA were associated with higher maximal SBP during exercise test and DGLA also with higher VO2max but neither with ECP. In conclusion, especially LA concentration was associated with higher ECP. This may provide one mechanism for the cardioprotective properties of, especially, LA.

Roles of Palmitoleic Acid and Its Positional Isomers, Hypogeic and Sapienic Acids, in Inflammation, Metabolic Diseases and Cancer

In the last few years, the monounsaturated hexadecenoic fatty acids are being increasingly considered as biomarkers of health with key functions in physiology and pathophysiology. Palmitoleic acid (16:1n-7) and sapienic acid (16:1n-10) are synthesized from palmitic acid by the action of stearoyl-CoA desaturase-1 and fatty acid desaturase 2, respectively. A third positional isomer, hypogeic acid (16:1n-9) is produced from the partial β-oxidation of oleic acid. In this review, we discuss the current knowledge of the effects of palmitoleic acid and, where available, sapienic acid and hypogeic acid, on metabolic diseases such as diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and cancer. The results have shown diverse effects among studies in cell lines, animal models and humans. Palmitoleic acid was described as a lipokine able to regulate different metabolic processes such as an increase in insulin sensitivity in muscle, β cell proliferation, prevention of endoplasmic reticulum stress and lipogenic activity in white adipocytes. Numerous beneficial effects have been attributed to palmitoleic acid, both in mouse models and in cell lines. However, its role in humans is not fully understood, and is sometimes controversial. Regarding sapienic acid and hypogeic acid, studies on their biological effects are still scarce, but accumulating evidence suggests that they also play important roles in metabolic regulation. The multiplicity of effects reported for palmitoleic acid and the compartmentalized manner in which they often occur, may suggest the overlapping actions of multiple isomers being present at the same or neighboring locations.

Serum n-6 polyunsaturated fatty acids and risk of atrial fibrillation: the Kuopio Ischaemic Heart Disease Risk Factor Study

Purpose

N-6 polyunsaturated fatty acids (PUFA), particularly linoleic acid (LA), have been associated with lower risk of coronary heart disease (CHD), but little is known about their antiarrhythmic properties. We investigated the association of the serum n-6 PUFAs with the risk of atrial fibrillation (AF), the most common type of cardiac arrhythmia.

Methods

The study included 2450 men from the Kuopio Ischaemic Heart Disease Risk Factor Study, aged 42–60 years at baseline. The total n-6 PUFA includes linoleic acid (LA), arachidonic acid (AA), γ-linolenic acid (GLA) and dihomo-γ-linolenic acid (DGLA). Cox proportional hazards regression was used to estimate hazard ratio (HR) of incident events.

Results

During the mean follow-up of 22.4 years, 486 AF cases occurred. The multivariable-adjusted HR in the highest versus the lowest quartile of total serum n-6 PUFA concentration was 0.79 (95% CI 0.58–1.08, P trend = 0.04). When evaluated individually, only serum LA concentration was inversely associated with AF risk (multivariable-adjusted extreme-quartile HR 0.69, 95% CI 0.51–0.94, P trend = 0.02). These associations were stronger among the men without history of CHD or congestive heart failure at baseline, compared to men with such disease history (P for interaction = 0.05 for total n-6 PUFA and LA). Similar associations were observed with dietary LA and AA intakes. No significant associations were observed with serum AA, GLA or DGLA concentrations.

Conclusions

Higher circulating concentration and dietary intake of n-6 PUFA, mainly LA, are associated with lower risk of AF, especially among men without history of CHD or congestive heart failure.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02780-0.

Palmitoleic Acid Protects against Hypertension by Inhibiting NF-κB-Mediated Inflammation

SCOPE

The role of palmitoleic acid (POA) in hypertension or blood pressure remains uncertain. This study aims to investigate the epidemiological association between circulating POA and primary hypertension in humans, and subsequently evaluate the effects of exogenous POA on blood pressure and aortic remodeling in spontaneously hypertensive rats (SHRs).

METHODS AND RESULTS

A case-control study of 349 hypertensive and 1396 normotensive children and adolescents is conducted, and found hypertensive cases show significant lower erythrocyte phospholipid POA than normotensive controls (p < 0.001). In conditional logistic regression model, participants in the top quartile of POA have a lower prevalence of primary hypertension than those in the bottom (multivariate-adjusted OR: 0.47, 95% CI: 0.25-0.89). In animal study, 24 SHRs are randomly assigned to n-3 PUFAs (500 mg kg-1 ), POA (500 mg kg-1 ), or vehicle (olive oil) for 8 weeks. At the end of intervention, as compared to SHRs treated with vehicle, SHRs treated with POA shows significantly decreased systolic blood pressure (SBP), improved aortic remodeling, and also decreased aortic expressions of NF-κB and its downstream proinflammatory cytokines.

CONCLUSIONS

Circulating POA is inversely associated with risk of primary hypertension, and exogenous POA supplementation can decrease SBP and improve aortic remodeling by inhibiting NF-κB-mediated inflammation.

Monounsaturated fatty acids protect against palmitate-induced lipoapoptosis in human umbilical vein endothelial cells

Diets high in saturated fatty acids are linked to increased cardiovascular disease risk, whereas monounsaturated fatty acids have been associated with improved cardiovascular outcomes. Accordingly, cell culture studies have demonstrated that saturated fatty acids, particularly long chain saturated fatty acids such as palmitate, induce dysfunction and cell death in a variety of cell types, and monounsaturated fatty acids may confer protection against palmitate-mediated damage. The aim of the present study was to examine whether monounsaturated fatty acids could protect against palmitate-mediated cell death in endothelial cells, to determine if AMPK inactivation and activation (via compound C and AICAR, respectively) underlies both palmitate-induced damage and monounsaturated fatty acid-mediated protection, and to explore the role of ER stress in this context. Human umbilical vein endothelial cells were examined for cell viability and apoptosis following treatment for 24 hours with palmitate (0.25 and 0.5mM) alone or in combination with the monounsaturated fatty acids oleate or palmitoleate (0.25 and 0.5mM), AICAR, compound C, 4μ8C, or TUDCA. Compared to control cells, palmitate significantly decreased cell viability and increased apoptosis in a dose-dependent manner. The monounsaturated fatty acids oleate and palmitoleate completely prevented the cytotoxic effects of palmitate. Although palmitate induced markers of ER stress, chemical inhibition of ER stress did not prevent palmitate-induced lipoapoptosis. Conversely, the AMPK activator AICAR (0.1 and 0.5mM) conferred protection from palmitate mediated-alterations in viability, apoptosis and ER stress, whereas the AMPK inhibitor compound C (20 and 40μM) significantly exacerbated palmitate-mediated damage. Lastly, co-incubation with palmitate, monounsaturated fatty acids, and compound C significantly mitigated the protective effects of both oleate and palmitoleate. In conclusion, monounsaturated fatty acids confer protection against the cytotoxic effects of palmitate in vascular endothelial cells; and palmitate-mediated damage, as well as monounsaturated-mediated protection, are due in part to inactivation and activation, respectively, of the metabolic regulator AMPK. These results may have implications for understanding the deleterious effects of high saturated fat diets on cardiovascular dysfunction and disease risk.

Trans-vaccenic acid inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells via a mitochondrial-mediated apoptosis pathway

Background

Intake of trans fatty acids (TFAs) from partially hydrogenated vegetable oil is associated with a variety of adverse outcomes, but little is known about the health effects of ruminant trans fats. Trans-vaccenic acid (TVA) is a naturally occurring TFA found in the fat of ruminants and in human dairy products. The present study was conducted to investigate the anticancer activity and underlying mechanisms of TVA on human nasopharyngeal carcinoma (NPC) 5-8F and CNE-2 cells.

Methods

A CCK8 assay was used to determine the effect of TVA and the Mcl-1 inhibitor S63845 on the proliferation of NPC cells. Apoptosis was measured using flow cytometry. Western blotting was used to detect the protein expression levels of factors associated with Bcl-2-family protein signaling and Akt signaling.

Results

TVA significantly inhibited cell proliferation in a dose-dependent manner. Mechanistic investigation demonstrated that TVA significantly decreased p-Akt levels and Bad phosphorylation on Ser-136 and Ser-112. More importantly, we discovered that the Mcl-1 inhibitor S63845 synergistically sensitized NPC cells to apoptosis induction by TVA.

Conclusion

TVA can inhibit NPC cell growth and induced apoptosis through the inhibition of Bad/Akt phosphorylation. The combined use of TVA and Mcl-1 inhibitors offers a potential advantage for nasopharyngeal cancer treatment.

Therapeutic targeting of lipid synthesis metabolism for selective elimination of cancer stem cells

Cancer stem cells (CSCs) are believed to have an essential role in tumor resistance and metastasis; however, no therapeutic strategy for the selective elimination of CSCs has been established. Recently, several studies have shown that the metabolic regulation for ATP synthesis and biological building block generation in CSCs are different from that in bulk cancer cells and rather similar to that in normal tissue stem cells. To take advantage of this difference for CSC elimination therapy, many studies have tested the effect of blocking these metabolism. Two specific processes for lipid biosynthesis, i.e., fatty acid unsaturation and cholesterol biosynthesis, have been shown to be very effective and selective for CSC targets. In this review, lipid metabolism specific to CSCs are summarized. In addition, how monounsaturated fatty acid and cholesterol synthesis may contribute to CSC maintenance are discussed. Specifically, the molecular mechanism required for lipid synthesis and essential for stem cell biology is highlighted. The limit and preview of the lipid metabolism targeting for CSCs are also discussed.

Palmitoleic Acid has Stronger Anti-Inflammatory Potential in Human Endothelial Cells Compared to Oleic and Palmitic Acids

SCOPE

Fatty acids (FAs) may affect endothelial cell (EC) function, influencing atherogenesis and inflammatory processes. Palmitoleic acid (POA) has been described as an anti-inflammatory FA. However, its effects on ECs are underexplored. This study compares the effects of POA with those of palmitic acid (PA) and oleic acid (OA) on EC inflammatory responses.

METHODS AND RESULTS

EAHy926 cells (EC lineage) are exposed to PA, OA, or POA, and stimulated with tumor necrosis factor (TNF)-α. Associated with the FA's own incorporation, PA induces a twofold increase in arachidonic acid, while POA increases the amount of cis-vaccenic acid. PA, but not OA, enhances the production of IL-6 and IL-8 in response to TNF-α. In contrast, POA decreases production of monocyte chemotactic protein (MCP)-1, IL-6, and IL-8 compared to PA. TNF-α increases surface intercellular adhesion molecule-1 expression previously decreased by POA. TNF-α stimulation increases the expression of NFκB, cyclooxygenase (COX)-2, MCP-1, and IL-6 genes and reduces the expression of peroxisome proliferator-activated receptor (PPAR)-α gene. PA enhances the expression of MCP-1, IL-6, and COX-2 genes, while POA downregulates these genes, decreases expression of NFκB, and upregulates PPAR-α gene expression.

CONCLUSION

POA has anti-inflammatory effects on ECs stimulated with TNF-α and may counter endothelial dysfunction.

Is Palmitoleic Acid a Plausible Nonpharmacological Strategy to Prevent or Control Chronic Metabolic and Inflammatory Disorders?

Although dietary fatty acids can modulate metabolic and immune responses, the effects of palmitoleic acid (16:1n-7) remain unclear. Since this monounsaturated fatty acid is described as a lipokine, studies with cell culture and rodent models have suggested it enhances whole body insulin sensitivity, stimulates insulin secretion by β cells, increases hepatic fatty acid oxidation, improves the blood lipid profile, and alters macrophage differentiation. However, human studies report elevated blood levels of palmitoleic acid in people with obesity and metabolic syndrome. These findings might be reflection of the level or activity of stearoyl-CoA desaturase-1, which synthesizes palmitoleate and is enhanced in liver and adipose tissue of obese patients. The aim of this review is to describe the immune-metabolic effects of palmitoleic acid observed in cell culture, animal models, and humans to answer the question of whether palmitoleic acid is a plausible nonpharmacological strategy to prevent, control, or ameliorate chronic metabolic and inflammatory disorders. Despite the beneficial effects observed in cell culture and in animal studies, there are insufficient human intervention studies to fully understand the physiological effects of palmitoleic acid. Therefore, more human-based research is needed to identify whether palmitoleic acid meets the promising therapeutic potential suggested by the preclinical research.

Palmitoleic acid reduces the inflammation in LPS-stimulated macrophages by inhibition of NFκB, independently of PPARs

Palmitoleic acid (PM, 16:1n-7) has anti-inflammatory properties that could be linked to higher expression of PPARα, an inhibitor of NFκB. Macrophages play a major role in the pathogenesis of chronic inflammation, however, the effects of PM on macrophages are underexplored. Thus, we aimed to investigate the effects of PM in activated macrophages as well the role of PPARα. Primary macrophages were isolated from C57BL/6 wild type (WT) and PPARα knockout (KO) mice, cultured under standard conditions and exposed to lipopolysaccharides LPS (2.5 μg/ml) and PM 600 μmol/L conjugated with albumin for 24 hours. The stimulation with LPS increased the production of interleukin (IL)-6 and IL-1β while PM decreased the production of IL-6 in WT macrophages. In KO macrophages, LPS increased the production of tumour necrosis factor (TNF)-α and IL-6 and PM decreased the production of TNFα. The expression of inflammatory markers such NFκB and IL1β were increased by LPS and decreased by PM in both WT and KO macrophages. PM reduced the expression of MyD88 and caspase-1 in KO macrophages, and the expression of TLR4 and HIF-1α in both WT and KO macrophages, although LPS had no effect. CD86, an inflammatory macrophage marker, was reduced by PM independently of genotype. PM increased PPARγ and reduced PPARβ gene expression in macrophages of both genotypes, and increased ACOX-1 expression in KO macrophages. In conclusion, PM promotes anti-inflammatory effects in macrophages exposed to LPS through inhibition of inflammasome pathway, which was independent of PPARα, PPARϒ and AMPK, thus the molecular mechanisms of anti-inflammatory response caused by PM is still unclear.

Impact of physical activity on cardiovascular status in obesity

BACKGROUND

We have recently shown that being physically active (PA) counteracts, but not eliminates the increased risk of future cardiovascular disease in overweight and obese subjects. To investigate this further, we studied the impact of being normal weight, overweight and obese on multiple markers of subclinical cardiovascular disease in relation to physical activity.

MATERIALS AND METHODS

At age 70, 1016 subjects were investigated in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Being PA was defined as performing regular heavy exercise (self-reported). According to body mass index (BMI)/PA groups, the participants were categorized as PA/normal weight (BMI < 25 kg/m² , n = 104), non-PA/normal weight (n = 234), PA/overweight (BMI 25-29·9 kg/m² , n = 133), non-PA/overweight (n = 295), PA/obese (BMI ≥ 30 kg/m² , n = 54) and non-PA/obese (n = 169). Several different measurements of endothelial reactivity and arterial compliance (plethysmography and ultrasound), cartotid artery atherosclerosis and echocardiography were performed, and seven markers of coagulation/fibrinolysis were measured.

RESULTS

Physically active subjects with obesity showed impaired vasoreactivity in the forearm resistance vessels, increased left ventricular mass and impaired left ventricular systolic and diastolic functions, together with impaired coagulation/fibrinolysis when compared to PA/normal-weight subjects (P < 0·05 to <0·001). The majority of these disturbances were seen also in PA/overweight subjects when compared to PA/normal-weight subjects (P < 0·05 to <0·001).

CONCLUSIONS

Our data provide additional support for the notion that an increased level of self-reported physical activity does not fully eliminate the deleterious cardiovascular consequences associated with overweight and obesity.

The Role of the Novel Lipokine Palmitoleic Acid in Health and Disease

The monounsaturated fatty acid palmitoleate (palmitoleic acid) is one of the most abundant fatty acids in serum and tissues, particularly adipose tissue and liver. Its endogenous production by stearoyl-CoA desaturase 1 gives rise to its cis isoform, cis-palmitoleate. Although trans-palmitoleate is also synthesized in humans, it is mainly found as an exogenous source in ruminant fat and dairy products. Recently, palmitoleate was considered to be a lipokine based on evidence demonstrating its release from adipose tissue and its metabolic effects on distant organs. After this finding, research has been performed to determine whether palmitoleate has beneficial effects on metabolism and to elucidate the underlying mechanisms. Thus, the aim of this work was to review the current status of knowledge about palmitoleate, its metabolism, and its influence on metabolic abnormalities. Results have shown mixed cardiovascular effects, direct or inverse correlations with obesity, and hepatosteatosis, but a significant amelioration or prevention of insulin resistance and diabetes. Finally, the induction of palmitoleate release from adipose tissue, dietary intake, and its supplementation are all interventions with a potential impact on certain metabolic diseases.

Maternal Weight Gain Regulates Omega-3 Fatty Acids in Male, Not Female, Neonates

The fetus largely depends on maternal supply and placental transport for its source of long-chain polyunsaturated fatty acids (LCPUFAs), which are essential for proper neurological and cardiovascular development. Pregnancy complications such as diabetes reduces neonatal LCPUFA supply, but little is known of how fatty acid delivery is affected by maternal body type or weight gain in uncomplicated pregnancies. In a cross-sectional study of maternal-neonatal pairs at term, we sought to determine the effect of gestational weight gain on neonatal LCPUFA supply. Forty maternal-neonatal pairs of uncomplicated (no gestational hypertension or diabetes) term pregnancies were recruited upon admission to Oregon Health & Science University Labor & Delivery for scheduled cesarean section. Maternal and umbilical cord plasma fatty acid profiles were measured using gas chromatography-mass spectrophotometry. First trimester weight gain was negatively correlated with maternal n-3 LCPUFA ( r = -0.80, P = .0002), and this was not affected by fetal sex. High maternal weight gain in the first trimester was negatively associated with cord n-3 polyunsaturated fatty acid levels ( r = -0.70, P = .03) and placental thickness ( r = -0.69, P = .03) in male, but not female, offspring. High maternal weight gain in the first trimester is associated with a thinner placenta and low levels of n-3 LCPUFA in male offspring. Further study is required to confirm that male offspring are at a higher risk of poor outcomes associated with high maternal weight gain early in pregnancy.

Exercise-induced vasodilation in healthy males: A marker of reduced endothelial function

OBJECTIVES

Reduced arterial vasodilatatory capacity is a marker of coronary heart disease. The aim was to investigate if the difference between the vasodilatory response before and after exercise, as assessed by non-invasive methodology, is related to endothelial and inflammatory biomarkers.

DESIGN

Post-ischemic hyperemia after 5 min of arterial occlusion was examined before and after a bicycle test with strain-gauge plethysmography (measuring peak reactive hyperemia in the forearm) and peripheral arterial tonometry (PAT hyperemia ratio: measuring pulse waves in the index finger relative to the contra-lateral index finger) in 30 healthy males. A low PAT hyperemia ratio or a low peak reactive hyperemia reflects endothelial dysfunction. Inflammatory and endothelial biomarkers were assessed.

RESULTS

A low peak reactive hyperemia and a low PAT hyperemia ratio before the bicycle test was associated with a high percentage increase in peak reactive hyperemia after exercise (r = - 0.68, p < 0.001; r = - 0.35, p = 0.06, respectively). Asymmetric dimethylarginine and interleukin-10 were associated with the percentage increase in peak reactive hyperemia in multiple linear regression analyses (β: 165 (confidence interval [CI], 34-296), p = 0.02; β: 19 (CI, - 0.5-39), p = 0.06, respectively).

CONCLUSIONS

The difference in the vasodilatory response before and after exercise, as assessed by non-invasive methodology, is related to endothelial and inflammatory biomarkers in healthy males.

Overexpression of stearoyl-CoA desaturase 1 in bone marrow mesenchymal stem cells enhance the expression of induced endothelial cells

Background

Bone marrow mesenchymal stem cells (BM-MSCs) are capable of differentiating into endothelial cells in vitro and acquire major characteristics of mature endothelial-like expression of vWF and CD31. SFAs and lipid oxidation products have been linked with postprandial endothelial dysfunction. Consumption of SFAs impairs arterial endothelial function, while a Mediterranean-type MUFA-diet has a beneficial effect on endothelial function by producing a decrease in levels of vWF, TFPI and PAI-1. Stearoyl-CoA desaturase 1 (SCD1), which converts SFA to MUFA, is involved in the cellular biosynthesis of MUFAs from SFA substrates. High expression of SCD1 is corresponded with low rates of fatty acid oxidation, therefore it might reduce inflammatory responses and be beneficial for the growth of induced endothelial cells. Overexpression of SCD1 in BM-MSCs might increase the growth of induced endothelial cells. The goal of this research is to study the relationship between overexpression of SCD1 and the expression of induced endothelial cells in BM-MSCs in vitro.

Methods

The gene SCD1 was integrated into a lentiviral vector, and then 293 T cells were transfected by the connected product to produce a packaged virus. BM-MSCs were infected by the packaged virus. Cell culture and endothelial induction were performed. Fluorescent quantitative PCR of CD31, vWF and VE-cad was performed after 1 week and 2 weeks to test the growth of induced endothelial cells.

Results

The mRNA amount of CD31, vWF and VE-cad of the SCD1 overexpressed group was statistically higher than that of the empty vector (EV) group and that of the normal group after 1 week and 2 weeks, respectively (p < 0.05). Immunocytochemical staining of CD31 or vWF was detected by visualizing red color.

Conclusions

This study suggested that overexpression of SCD1 in BM-MSCs could increase the expression of induced endothelial cells in vitro.

Associations of erythrocyte palmitoleic acid with adipokines, inflammatory markers, and the metabolic syndrome in middle-aged and older Chinese

BACKGROUND

Palmitoleic acid has been shown to regulate adipokine expression and systemic metabolic homeostasis in animal studies. However, its association with human metabolic diseases remains controversial.

OBJECTIVE

We aimed to investigate associations of erythrocyte palmitoleic acid with adipokines, inflammatory markers, and metabolic syndrome (MetS) in a Chinese population.

DESIGN

Erythrocyte fatty acids were measured in a population-based sample of 3107 men and women aged 50-70 y, for whom plasma glucose, insulin, lipid profile, adiponectin, retinol binding protein 4 (RBP-4), plasminogen activator inhibitor type 1, and high-sensitivity C-reactive protein (hsCRP) were measured. MetS was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans.

RESULTS

The mean (±SD) erythrocyte palmitoleic acid value was 0.41 ± 0.20% of total fatty acids. Palmitoleic acid was positively correlated with RBP-4 (r = 0.14, P < 0.001) and inversely correlated with adiponectin (r = -0.15, P < 0.001). After multivariable adjustment, palmitoleic acid was strongly associated with MetS and its components. ORs (95% CIs) for comparisons of extreme quartiles of palmitoleic acid were 3.50 (2.66, 4.59) for MetS, 7.88 (5.90, 10.52) for hypertriglyceridemia, 2.13 (1.66, 2.72) for reduced HDL cholesterol, 1.99 (1.60, 2.48) for central obesity, and 1.86 (1.41, 2.44) for elevated blood pressure (all P < 0.001). Further control for adipokines and hsCRP abolished the association of palmitoleic acid with central obesity but not with other MetS components.

CONCLUSION

Erythrocyte palmitoleic acid is associated with an adverse profile of adipokines and inflammatory markers and an increased risk of MetS in this Chinese population.

A review of the evidence for the effects of total dietary fat, saturated, monounsaturated and n-6 polyunsaturated fatty acids on vascular function, endothelial progenitor cells and microparticles

Vascular dysfunction is recognised as an integrative marker of CVD. While dietary strategies aimed at reducing CVD risk include reductions in the intake of SFA, there are currently no clear guidelines on what should replace SFA. The purpose of this review was to assess the evidence for the effects of total dietary fat and individual fatty acids (SFA, MUFA and n-6 PUFA) on vascular function, cellular microparticles and endothelial progenitor cells. Medline was systematically searched from 1966 until November 2010. A total of fifty-nine peer-reviewed publications (covering fifty-six studies), which included five epidemiological, eighteen dietary intervention and thirty-three test meal studies, were identified. The findings from the epidemiological studies were inconclusive. The limited data available from dietary intervention studies suggested a beneficial effect of low-fat diets on vascular reactivity, which was strongest when the comparator diet was high in SFA, with a modest improvement in measures of vascular reactivity when high-fat, MUFA-rich diets were compared with SFA-rich diets. There was consistent evidence from the test meal studies that high-fat meals have a detrimental effect on postprandial vascular function. However, the evidence for the comparative effects of test meals rich in MUFA or n-6 PUFA with SFA on postprandial vascular function was limited and inconclusive. The lack of studies with comparable within-study dietary fatty acid targets, a variety of different study designs and different methods for determining vascular function all confound any clear conclusions on the impact of dietary fat and individual fatty acids on vascular function.

Trans-palmitoleic acid, metabolic risk factors, and new-onset diabetes in U.S. adults: a cohort study

BACKGROUND

Palmitoleic acid (cis-16:1n-7), which is produced by endogenous fat synthesis, has been linked to both beneficial and deleterious metabolic effects, potentially confounded by diverse determinants and tissue sources of endogenous production. Trans-palmitoleate (trans-16:1n-7) represents a distinctly exogenous source of 16:1n-7, unconfounded by endogenous synthesis or its determinants, that may be uniquely informative.

OBJECTIVE

To investigate whether circulating trans-palmitoleate is independently related to lower metabolic risk and incident type 2 diabetes.

DESIGN

Prospective cohort study from 1992 to 2006.

SETTING

Four U.S. communities.

PATIENTS

3736 adults in the Cardiovascular Health Study.

MEASUREMENTS

Anthropometric characteristics and levels of plasma phospholipid fatty acids, blood lipids, inflammatory markers, and glucose-insulin measured at baseline in 1992 and dietary habits measured 3 years earlier. Multivariate-adjusted models were used to investigate how demographic, clinical, and lifestyle factors independently related to plasma phospholipid trans-palmitoleate; how trans-palmitoleate related to major metabolic risk factors; and how trans-palmitoleate related to new-onset diabetes (304 incident cases). Findings were validated for metabolic risk factors in an independent cohort of 327 women.

RESULTS

In multivariate analyses, whole-fat dairy consumption was most strongly associated with higher trans-palmitoleate levels. Higher trans-palmitoleate levels were associated with slightly lower adiposity and, independently, with higher high-density lipoprotein cholesterol levels (1.9% across quintiles; P = 0.040), lower triglyceride levels (-19.0%; P < 0.001), a lower total cholesterol-HDL cholesterol ratio (-4.7%; P < 0.001), lower C-reactive protein levels (-13.8%; P = 0.05), and lower insulin resistance (-16.7%, P < 0.001). Trans-palmitoleate was also associated with a substantially lower incidence of diabetes, with multivariate hazard ratios of 0.41 (95% CI, 0.27 to 0.64) and 0.38 (CI, 0.24 to 0.62) in quintiles 4 and 5 versus quintile 1 (P for trend < 0.001). Findings were independent of estimated dairy consumption or other fatty acid dairy biomarkers. Protective associations with metabolic risk factors were confirmed in the validation cohort.

LIMITATION

Results could be affected by measurement error or residual confounding.

CONCLUSION

Circulating trans-palmitoleate is associated with lower insulin resistance, presence of atherogenic dyslipidemia, and incident diabetes. Our findings may explain previously observed metabolic benefits of dairy consumption and support the need for detailed further experimental and clinical investigation.

PRIMARY FUNDING SOURCE

National Heart, Lung, and Blood Institute and National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health.

Acute effects of elevated NEFA on vascular function: a comparison of SFA and MUFA

There is emerging evidence to show that high levels of NEFA contribute to endothelial dysfunction and impaired insulin sensitivity. However, the impact of NEFA composition remains unclear. A total of ten healthy men consumed test drinks containing 50 g of palm stearin (rich in SFA) or high-oleic sunflower oil (rich in MUFA) on separate occasions; a third day included no fat as a control. The fats were emulsified into chocolate drinks and given as a bolus (approximately 10 g fat) at baseline followed by smaller amounts (approximately 3 g fat) every 30 min throughout the 6 h study day. An intravenous heparin infusion was initiated 2 h after the bolus, which resulted in a three- to fourfold increase in circulating NEFA level from baseline. Mean arterial stiffness as measured by digital volume pulse was higher during the consumption of SFA (P < 0·001) but not MUFA (P = 0·089) compared with the control. Overall insulin and gastric inhibitory peptide response was greater during the consumption of both fats compared with the control (P < 0·001); there was a second insulin peak in response to MUFA unlike SFA. Consumption of SFA resulted in higher levels of soluble intercellular adhesion molecule-1 (sI-CAM) at 330 min than that of MUFA or control (P ≤ 0·048). There was no effect of the test drinks on glucose, total nitrite, plasminogen activator inhibitor-1 or endothelin-1 concentrations. The present study indicates a potential negative impact of elevated NEFA derived from the consumption of SFA on arterial stiffness and sI-CAM levels. More studies are needed to fully investigate the impact of NEFA composition on risk factors for CVD.

Circulating palmitoleic acid and risk of metabolic abnormalities and new-onset diabetes

BACKGROUND

Animal experiments suggest that circulating palmitoleic acid (cis-16:1n-7) from adipocyte de novo fatty acid synthesis may directly regulate insulin resistance and metabolic dysregulation.

OBJECTIVE

We investigated the independent determinants of circulating palmitoleate in free-living humans and whether palmitoleate is related to lower metabolic risk and the incidence of diabetes.

DESIGN

In a prospective cohort of 3630 US men and women in the Cardiovascular Health Study, plasma phospholipid fatty acids, anthropometric variables, blood lipids, inflammatory markers, and glucose and insulin concentrations were measured between 1992 and 2006 by using standardized methods. Independent determinants of plasma phospholipid palmitoleate and relations of palmitoleate with metabolic risk factors were investigated by using multivariable-adjusted linear regression. Relations with incident diabetes (296 incident cases) were investigated by using Cox proportional hazards.

RESULTS

The mean (± SD) palmitoleate value was 0.49 ± 0.20% (range: 0.11-2.55%) of total fatty acids. Greater body mass index, carbohydrate intake, protein intake, and alcohol use were each independent lifestyle correlates of higher palmitoleate concentrations. In multivariable analyses that adjusted for these factors and other potential confounders, higher palmitoleate concentrations were independently associated with lower LDL cholesterol (P < 0.001), higher HDL cholesterol (P < 0.001), lower total:HDL-cholesterol ratio (P = 0.04), and lower fibrinogen (P < 0.001). However, palmitoleate was also associated with higher triglycerides (P < 0.001) and (in men only) with greater insulin resistance (P < 0.001). Palmitoleate was not significantly associated with incident diabetes.

CONCLUSIONS

Adiposity (energy imbalance), carbohydrate consumption, and alcohol use-even within typical ranges-are associated with higher circulating palmitoleate concentrations. Circulating palmitoleate is robustly associated with multiple metabolic risk factors but in mixed directions, perhaps related to divergent lifestyle determinants or endogenous sources (liver, adipose tissue) of fatty acid synthesis.

Influence of demographic and metabolic variables on forearm blood flow and vascular conductance in individuals without overt heart disease

PURPOSE

Vascular reactivity is involved in the regulation of vascular function either in normal conditions or in the pathophysiology of cardiovascular diseases. We tested the hypothesis that vascular reactivity evaluated by forearm blood flow may vary according to demographic and metabolic variables in a cohort of individuals without any evidence of heart disease after clinical examination.

SUBJECTS AND METHODS

We studied 186 individuals (mean age 41.4 years, standard deviation 13.1 years; 95 (51%) men and 91 (49%) women. We investigated forearm blood flow and vascular conductance with venous occlusion plethysmography at baseline, during handgrip isometric exercise and during the recovery phase. Demographic and laboratory data were collected. Statistical analysis was performed with mixed linear models appropriate for repeated measurements.

RESULTS

Mean forearm blood flow values in the different study conditions ranged between 1.7+/-0.47 mL.min(-1).100 mL(-1) of tissue and 2.82+/-1.13 mL.min(-1).100 mL(-1) of tissue. Forearm blood flow was higher in men than in women (P<0.005) and increased as the heart rate increased during handgrip maneuver (P<0.0001). Serum triglyceride levels were inversely related to forearm blood flow at baseline, during isometric exercise and recovery phase (P=0.0209). Body mass index was inversely related to forearm vascular conductance at baseline, during isometric exercise and recovery phase (P=0.0223).

CONCLUSION

Our findings suggest that forearm blood flow and vascular conductance as a surrogate of the vascular function may be influenced by gender, heart rate, serum triglyceride levels and body mass index in individuals without overt heart disease.

Associations of circulating adiponectin with measures of vascular function and morphology

CONTEXT

Some previous studies have reported an association between circulating adiponectin and selected measures of vascular function and morphology, but most of these studies have been performed in small samples of patients with preexisting disease.

OBJECTIVE

We aimed to evaluate associations between circulating adiponectin and comprehensive measures of vascular function and morphology in a large sample of individuals from the community.

DESIGN, SETTINGS, AND PARTICIPANTS

We conducted a cross-sectional investigation of 981 70-yr-old participants (50% women) of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS).

MAIN OUTCOME MEASURES

Measures of outcome included vascular function [common carotid artery (CCA) distensibility, flow-mediated dilation, endothelium-dependent and endothelium-independent vasodilation using invasive methods] and vascular morphology [intima-media (IM) thickness, plaque presence, gray scale median (GSM) in the IM and plaques].

RESULTS

In age- and sex-adjusted models, adiponectin was positively associated with IM-GSM, plaque GSM, CCA distensibility, endothelium-dependent and endothelium-independent vasodilation. In multivariable models (with additional adjustment for body mass index; systolic blood pressure; antihypertensive, antidiabetic, and lipid-lowering medication; fasting blood glucose; total cholesterol; high-density lipoprotein cholesterol; creatinine; and smoking), adiponectin remained positively associated with IM-GSM [beta = 2.06; 95% confidence interval (CI), 0.54, 3.58], plaque GSM (beta = 3.11; 95% CI, 0.36, 5.86), and CCA distensibility (beta = 0.04; 95% CI, 0.00, 0.07).

CONCLUSIONS

Serum levels of adiponectin were positively associated with IM-GSM and plaque GSM (indicating lower fat content in the IM and plaques) and CCA distensibility (indicating higher wall elasticity), independent of potential confounders. Our results imply that adiponectin is associated with less arterial pathology.

High levels of soluble intercellular adhesion molecule-1, insulin resistance and saturated fatty acids are associated with endothelial dysfunction in healthy adolescents

OBJECTIVE

Atherosclerosis begins and progresses during childhood and adolescence. Endothelial dysfunction is one of the earliest abnormalities that can be detected in the development of atherosclerosis. As the determinants of endothelial function in childhood are unknown, we investigated the influence of cardiovascular risk factors on endothelial function in a cohort of healthy adolescents.

METHODS

A total of 257 adolescents (age: 14.5 + or - 1.0 years, 138 girls) participated in this study. Endothelial function was measured as reactive hyperemic index (RHI) using a fingertip peripheral arterial tonometry device. Blood samples were collected for analysis of lipids, insulin, glucose, fatty acid composition of plasma phospholipids, and markers of inflammation and endothelial function.

RESULTS

There was no gender difference in RHI. Boys had higher plasma level of vascular cellular adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), P-selectin and monocyte chemoattractant protein-1, and lower level of insulin, total cholesterol, high-density lipoprotein-cholesterol (HDL), low-density lipoprotein-cholesterol (LDL), ApoA1, ApoB, and docosahexaenoic acid of plasma phospholipids than girls. There was no gender difference regarding triacylglycerol, triacylglycerol/HDL, LDL/HDL and ApoB/ApoA. The RHI was inversely associated with plasma ICAM-1 (p=0.0003), HOMA index for insulin resistance (HOMA-IR, p=0.001) and saturated fatty acids of plasma phospholipids (SFA, p=0.001). The associations remained significant after adjusting for age, height, BMI-z-score, sex, blood pressure, HDL and smoking.

CONCLUSION

In healthy adolescents impaired endothelial function is significantly associated with high level of soluble ICAM-1, HOMA-IR and SFA.

Evidence for a role of hot flushes in vascular function in recently postmenopausal women

OBJECTIVE

Observational studies indicate that postmenopausal hormone therapy (HT) prevents cardiovascular disease, but randomized clinical trials have not confirmed this effect. Hot flushes were more likely to be present in women starting HT in observational studies, whereas these symptoms were mild or absent among women attending randomized clinical trials. We hypothesized that vascular function may differ in women with and without vasomotor hot flushes.

METHODS

One hundred forty-three recently postmenopausal women showing a broad range of variation in hot flushes were studied with radial artery tonometry. Pulse wave analyses were assessed at baseline and after nitroglycerin and salbutamol challenges. Wilcoxon signed rank test was used for paired comparisons after challenges with nitroglycerin and salbutamol.

RESULTS

Neither baseline arterial stiffness nor endothelial function differed between women without or with mild, moderate, or severe hot flushes. However, after nitroglycerin challenge, the time to the onset of the reflected wave (dependent on pulse wave velocity) was 9.5% longer (P=.014), and the time to the first systolic peak (dependent on the rapid phase of ventricular ejection) was 13.9% longer (P=.025) in women with severe hot flushes as compared with asymptomatic women.

CONCLUSION

Women with severe vasomotor hot flushes show greater vascular responsiveness to nitroglycerin than women without hot flushes. This may partially explain the conflicting data between observational and randomized HT studies.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00668603

LEVEL OF EVIDENCE

II.

Triacylglycerol structure and interesterification of palmitic and stearic acid-rich fats: an overview and implications for cardiovascular disease

The position of fatty acids in the TAG molecule (sn-1, sn-2 and sn-3) determines the physical properties of the fat, which affects its absorption, metabolism and distribution into tissues, which may have implications for the risk of CHD. The TAG structure of fats can be manipulated by the process of interesterification, which is of increasing commercial importance, as it can be used to change the physical characteristics of a fat without the generation of trans-fatty acids. Interesterified fats rich in long-chain SFA are commercially important, but few studies have investigated their health effects. Evidence from animal and human infant studies suggests that TAG structure and interesterification affect digestibility, atherogenicity and fasting lipid levels, with fats containing palmitic and stearic acid in the sn-2 position being better digested and considered to be more atherogenic. However, chronic studies in human adults suggest that TAG structure has no effect on digestibility or fasting lipids. The postprandial effects of fats with differing TAG structure are better characterised but the evidence is inconclusive; it is probable that differences in the physical characteristics of fats resulting from interesterification and changes in TAG structure are key determinants of the level of postprandial lipaemia, rather than the position of fatty acids in the TAG. The present review gives an overview of TAG structure and interesterified palmitic and stearic acid-rich fats, their physical properties and their acute and chronic effects in human adults in relation to CHD.

Dietary saturated and unsaturated fats as determinants of blood pressure and vascular function

The amount and type of dietary fat have long been associated with the risk of CVD. Arterial stiffness and endothelial dysfunction are important risk factors in the aetiology of CHD. A range of methods exists to assess vascular function that may be used in nutritional science, including clinic and ambulatory blood pressure monitoring, pulse wave analysis, pulse wave velocity, flow-mediated dilatation and venous occlusion plethysmography. The present review focuses on the quantity and type of dietary fat and effects on blood pressure, arterial compliance and endothelial function. Concerning fat quantity, the amount of dietary fat consumed habitually appears to have little influence on vascular function independent of fatty acid composition, although single high-fat meals postprandially impair endothelial function compared with low-fat meals. The mechanism is related to increased circulating lipoproteins and NEFA which may induce pro-inflammatory pathways and increase oxidative stress. Regarding the type of fat, cross-sectional data suggest that saturated fat adversely affects vascular function whereas polyunsaturated fat (mainly linoleic acid (18 : 2n-6) and n-3 PUFA) are beneficial. EPA (20 : 5n-3) and DHA (22 : 6n-3) can reduce blood pressure, improve arterial compliance in type 2 diabetics and dyslipidaemics, and augment endothelium-dependent vasodilation. The mechanisms for this vascular protection, and the nature of the separate physiological effects induced by EPA and DHA, are priorities for future research. Since good-quality observational or interventional data on dietary fatty acid composition and vascular function are scarce, no further recommendations can be suggested in addition to current guidelines at the present time.

Endothelial dysfunction and serum fatty acid composition in patients with type 2 diabetes mellitus

The aim of this study was to evaluate the possible association between serum fatty acids composition and endothelial dysfunction in patients with type 2 diabetes mellitus. A cross-sectional study was conducted with 125 normo- or microalbuminuric type 2 diabetes mellitus patients with serum creatinine <1.5 mg/dL. Serum fatty acids composition (gas chromatography), serum levels of endothelin-1 (ET-1) (enzyme-linked immunosorbent assay), fibrinogen, serum C-reactive protein, lipids, homeostasis model assessment resistance index (HOMA-R), and 24-hour urinary albumin excretion rate were measured. Serum levels of ET-1 were positively correlated with saturated fatty acids (r = 0.257, P = .025) and negatively correlated with polyunsaturated fatty acids (PUFAs) (r = -0.319, P = .005). Serum ET-1 levels were also positively correlated with systolic blood pressure, waist circumference, total cholesterol levels, triglycerides, and HOMA-R. In multiple linear regression models, only saturated fatty acids (R(2) = 0.317, P = .002) or PUFAs (R(2) = 0.314, P = .001) remained associated with ET-1 levels. Models were adjusted for systolic blood pressure, HOMA-R, waist circumference, triglycerides, body mass index, and smoking habit. The serum total PUFA levels showed an inverse correlation with urinary albumin excretion rate (r = -0.248, P = .012). In conclusion, in type 2 diabetes mellitus patients, the serum fatty acids composition was independently related to endothelial function evaluated by serum ET-1. Saturated fatty acids were associated with endothelial dysfunction (high levels of ET-1), whereas PUFAs had a protective role in endothelial function.

Equol production capability is associated with favorable vascular function in postmenopausal women using tibolone; no effect with soy supplementation

OBJECTIVE

Equol, a gut bacterial metabolite of isoflavone daidzein, may improve health through changes in vascular function and in estrogen metabolism. Tibolone, a synthetic steroid alternative for the treatment of postmenopausal symptoms, causes a different estrogenic milieu than estrogen and may affect vascular health. We studied the effects of equol production and soy supplementation on vascular function in postmenopausal women under long-term tibolone use.

METHODS

We screened 110 women using tibolone for 3-60 months for high equol production capacity with a one-week soy challenge. Twenty women with high equol production capacity (4-fold elevation in equol level) and 20 comparable control women without this capacity were treated in a randomized placebo-controlled cross-over trial with a soy drink (52 g of soy protein containing 112 mg of isoflavones) or placebo for 8 weeks. Arterial stiffness and endothelial function were assessed before and after soy and placebo supplementation with pulse-wave analysis.

RESULTS

Prior to soy supplementation arterial stiffness, expressed as augmentation index, was lower (p=0.01) in equol producers (25.9+/-1.1%) than non-equol producers (29.6+/-0.9%). Similarly, endothelial function index was better at baseline (p=0.009) in these women (72.3+/-5.3%) compared to women lacking equol production capacity (55.2+/-3.8%). Soy supplementation had no effect on arterial stiffness or endothelial function in either group.

CONCLUSION

In postmenopausal tibolone users, endogenous equol production capability is associated with favorable vascular function. This phenomenon was not affected by soy and thus, equol producing capacity may be an independent vascular health marker, at least in postmenopausal women using tibolone.

Impaired Endothelial Function of Forearm Resistance Arteries in CADASIL Patients

Background and Purpose— Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary arteriopathy, which mainly involves the brain causing stroke and dementia. Mice expressing the mutated protein display early dysfunction in vasoreactivity in resistance arteries, but studies of patients have been inconclusive so far.

Methods— We examined peripheral endothelium-dependent vasodilatation in 10 CADASIL-patients and 20 controls using 3 methods: venous occlusion plethysmography of forearm blood flow with intraarterial acetylcholine and sodium nitroprusside infusions for evaluation of resistance arteries, ultrasound with flow mediated vasodilatation (FMD) of the brachial artery for evaluation of a conduit artery, and the pulse wave method with measurements before and after terbutaline for evaluation of systemic endothelium-dependent vasodilation.

Results— The CADASIL patients displayed reductions in both basal ( P =0.034) and stimulated blood flow ( P =0.023 for the highest dose of acetylcholine) and an impaired endothelium-dependent vasodilation when investigated in forearm resistance arteries ( P =0.019). The FMD and the pulse wave method did not show any reduction in endothelium-dependent vasodilation in the patients.

Conclusions— Endothelium-dependent vasodilation was impaired in resistance arteries, but not in a conduit artery, in the forearm of CADASIL patients.

Mental stress impairs endothelial vasodilatory function by a beta-adrenergic mechanism

Mental stress has been shown to impair endothelium-dependent vasodilation (EDV) in the human forearm. The aim of this study was to investigate if this response could be blunted by local infusions of beta-blockade (propranolol), alpha-blockade (phentolamine), or neurogenic blockade. Thirty-one young healthy volunteers underwent forearm blood flow (FBF) measurements, using venous occlusion plethysmography, during local intra-arterial infusions of metacholine (MCh; inducing EDV) and sodium nitroprussid (SNP; inducing endothelial-independent vasodilation [EIDV]), respectively. These measurements were repeated during a 5-min mental arithmetic stress test without (n = 8) or with concomitant local infusion of propranolol (n = 7) or phentolamine (n = 8) in the forearm or during axillary plexus blockade (n = 8). An index of endothelial vasodilatory function (EFI) was calculated as the EDV to EIDV ratio. Mental stress impaired EDV significantly (p < .05), and as a result, EFI was significantly reduced (p = .02). This effect on EFI could be blocked by propranolol and neurogenic blockade but not by phentolamine (p < .05). Thus, impairment of endothelial vasodilatory function induced by mental stress could be blocked by beta-adrenergic, but not alpha-adrenergic, receptor blockade.

Comparative effects of fatty acids on endothelial inflammatory gene expression

BACKGROUND

Endothelial dysfunction may be related to adverse effects of some dietary fatty acids (FAs). Although in vitro studies have failed to show consistent findings, this may reflect the diverse experimental protocols employed and the limited range of FAs and end points studied.

AIMS

To investigate the effect of dietary FA type (saturated, monounsaturated, n-6 and n-3 polyunsaturated fatty acids), concentration, incubation time and cell stimulation state, on a broad spectrum of endothelial inflammatory gene expression.

METHODS

Using human umbilical vein endothelial cells, with and without stimulation (+/-10 ng/ml TNFalpha), the effects of arachidonic (AA), docosahexaenoic (DHA), eicosapentaenoic (EPA), linoleic (LA), oleic (OA) and palmitic acids (PA) (10, 25 and 100 microM), on the expression of genes encoding a number of inflammatory proteins and transcription factors were assessed by quantitative real time RT-PCR.

RESULTS

Individual FAs differentially affect endothelial inflammatory gene expression in a gene-specific manner. EPA, LA and OA significantly up-regulated MCP-1 gene expression compared to AA (p = 0.001, 0.013, 0.008, respectively) and DHA (p < 0.0005, = 0.004, 0.002, respectively). Furthermore, cell stimulation state and FA incubation time significantly influenced reported FA effects on gene expression.

CONCLUSION

The comparative effects of saturated, monounsaturated, n-6 and n-3 polyunsaturated FAs on endothelial gene expression depend on the specific FA investigated, its length of incubation, cell stimulation state and the gene investigated. These findings may explain existing disparity in the literature.

The diversity of health effects of individual trans fatty acid isomers

There are multiple adverse effects of trans fatty acids (TFA) that are produced by partial hydrogenation (i.e., manufactured TFA), on CVD, blood lipids, inflammation, oxidative stress, endothelial health, body weight, insulin sensitivity, and cancer. It is not yet clear how specific TFA isomers vary in their biological activity and mechanisms of action. There is evidence of health benefits on some of the endpoints that have been studied for some animal TFA isomers, such as conjugated linoleic acid; however, these are not a major TFA source in the diet. Future research will bring clarity to our understanding of the biological effects of the individual TFA isomers. At this point, it is not possible to plan diets that emphasize individual TFA from animal sources at levels that would be expected to have significant health effects. Due to the multiple adverse effects of manufactured TFA, numerous agencies and governing bodies recommend limiting TFA in the diet and reducing TFA in the food supply. These initiatives and regulations, along with potential TFA alternatives, are presented herein.

Vasodilation in resistance arteries is related to the apolipoprotein B/A1 ratio in the elderly – The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study

BACKGROUND

Recent studies have shown the apolipoprotein B to apolipoprotein A1 ratio (apoB/A1) to be superior to LDL-cholesterol measurements to predict cardiovascular events. The present study aims to relate apoB/A1 to endothelium-dependent vasodilation, an early marker of atherosclerosis, in the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study.

METHODS AND RESULTS

In this population-based study, 1016 subjects aged 70 years were evaluated by the invasive forearm technique with acetylcholine (EDV), brachial artery ultrasound to assess flow-mediated vasodilation (FMD) and pulse wave analysis with a beta-2 receptor agonist challenge, terbutaline. EDV and the pulse wave response, but not FMD, were related to apoB/A1 levels (r=-0.11, p=0.0038 for EDV, r=-0.16, p<0.0001 for the pulse wave analysis and r=0.01, p=0.65 for FMD). Neither LDL-cholesterol, nor non-HDL-cholesterol, was significantly related to the measurements of endothelium-dependent vasodilation. Also endothelium-independent vasodilation (EIDV) evaluated by the invasive forearm technique with sodium nitroprusside was related to apoB/A1 levels (r=-0.12, p<0.0016).

CONCLUSION

The apoB/A1 levels, but not LDL-cholesterol, were inversely related to endothelium-dependent vasodilation evaluated by EDV and pulse wave analysis, but not by FMD. Also EIDV showed the same pattern, suggesting a general deterioration in vasoreactivity mainly in resistance arteries in elderly subjects with high apoB/A1 levels.

Withdrawal of red meat from the usual diet reduces albuminuria and improves serum fatty acid profile in type 2 diabetes patients with macroalbuminuria

BACKGROUND

Replacement of red meat in the diet with chicken has reduced the urinary albumin excretion rate (UAER) and serum cholesterol in microalbuminuric type 2 diabetes patients. The effects of withdrawing red meat are unknown in the more advanced stages of diabetic nephropathy.

OBJECTIVE

Our objective was to assess the effects of replacing red meat in the usual diet (UD) with chicken (CD) and of consuming a lactovegetarian low-protein diet (LPD) on renal function, fatty acid, and lipid profile in macroalbuminuric type 2 diabetes patients.

DESIGN

A crossover controlled trial was conducted in 17 type 2 diabetes patients with macroalbuminuria (24-h UAER > or = 200 microg/min). Each patient followed the UD, CD, and LPD in a random order for 4 wk. After each diet, glomerular filtration rate, UAER, serum fatty acid, lipid profile, glycemic control, anthropometric indexes, and blood pressure were measured.

RESULTS

UAER [median CD: 269.4 (range: 111-1128) microg/min; LPD: 229.3 (76.6-999.3) microg/min; UD: 312.8 (223.7-1223.7) microg/min; P < 0.01] and mean (+/-SD) non-HDL cholesterol (CD: 3.92 +/- 0.99 mmol/L; LPD: 3.92 +/- 0.93 mmol/L; UD: 4.23 +/- 1.06 mmol/L; P = 0.042) were lower after CD and LPD than after UD. Compared with the UD, an increase in serum total polyunsaturated fatty acids was also observed (CD: 39.8 +/- 2.6%; LPD: 39.7 +/- 4.4%; UD: 37.3 +/- 3.1%; P = 0.029).

CONCLUSION

In macroalbuminuric patients with type 2 diabetes, withdrawing red meat from the diet reduces the UAER.

Metabolic syndrome and urinary cGMP excretion in general population

To examine the relationship between metabolic syndrome and endothelial dysfunction, we investigated cross-sectionally the correlation between metabolic risk factors and urinary excretion of cyclic guanosine 3',5'-monophosphate (cGMP), a second messenger of nitric oxide (NO), in 1541 Japanese men and women aged 40-79 years. The 24-h urinary excretion of cGMP was measured using a (125)I-labeled cGMP radioimmunoassay and was adjusted for urinary creatinine excretion (nmol/mmol creatinine). The components of metabolic syndrome were defined based on the following criteria: body mass index (BMI)> or =25.0 kg/m(2), fasting plasma glucose> or =6.11 mmol/l or non-fasting plasma glucose level> or =11.1 mmol/l, systolic blood pressure> or =130 mm Hg or diastolic blood pressure> or =85 mm Hg, high-density lipoprotein (HDL)-cholesterol<1.03 mmol/l for men and <1.29 mmol/l for women, and triglyceride> or =1.69 mmol/l. The number of components of metabolic syndrome correlated inversely with urinary cGMP excretion; means of cGMP excretion for the whole group adjusted for age, sex, and cardiovascular risk factors were 53.6, 48.6, 47.9, 44.4 and 42.3 nmol/mmol for 0, 1, 2, 3, and 4-5 components of metabolic syndrome, respectively (p=0.002). Our data suggest that a reduction of NO bioactivity concur with clustered features of the metabolic syndrome.

[The role of the diet as a risk factor for the development and progression of diabetic nephropathy]

Diabetic nephropathy (DN) is the leading cause of kidney disease in patients starting renal replacement therapy, and affects up to 40% of type 1 and type 2 diabetic patients. Diet seems to play an important role in the development of the disease. There are evidences supporting the concept that not only the amount but also the origin of dietary protein are associated with DN. Few studies analyzed the role of dietary lipids. A low-protein diet slows down the decline of renal function and ameliorates the DN prognosis and death in patients with type 1 diabetes with micro- and macroalbuminuria. Studies in type 2 diabetic patients are scanty but short-term studies suggest that this approach decreases albuminuria. However, the use of low-protein diet for long periods is compromised by poor compliance and its long-term safety is not firmly established. Enthusiastic results come up when comparing the effect of different sources of animal protein on renal function and lipid profile in patients with DN, which may represent an alternative strategy for low-protein diet on medical nutritional therapy in patients with DN and in cardiovascular risk factors and endothelial function.

PRETREATMENT WITH INTRAVENOUS ASCORBIC ACID PRESERVES ENDOTHELIAL FUNCTION DURING ACUTE HYPERGLYCAEMIA (R1)

1. Acute hyperglycaemia may impair endothelial function. Ascorbic acid (AA), administered intra-arterially, has been reported to improve endothelium-dependent vasodilatation during a forearm hyperglycaemic clamp. Using a randomized, double-blind, placebo-controlled, cross-over study, we investigated the potential for intravenous ascorbic acid to modify the endothelial response to acute systemic hyperglycaemia in humans. 2. Nine healthy male volunteers were recruited from the hospital staff. Endothelial function was determined by measuring the forearm blood flow responses to intrabrachial infusions of endothelium-dependent (ED) and endothelium-independent (EID) vasodilators. The endothelial function index (EFI) was derived from the ratio of ED and EID vasodilatation. Haemodynamic and endothelial function measurements were performed at baseline and then repeated 2 h after a systemic hyperglycaemic clamp (14 mmol/L). The subjects, studied on two separate occasions, were randomized to placebo or 2 g intravenous ascorbic acid prior to the initiation of hyperglycaemia. 3. After systemic hyperglycaemia with placebo pretreatment, the EFI fell from 1.08 +/- 0.21 to 0.74 +/- 0.13 (difference (95% confidence interval): 0.34 (0.20, 0.47); P < 0.001). When subjects were pretreated with ascorbic acid, the EFI was not affected by hyperglycaemia (1.11 +/- 0.21 to 1.12 +/- 0.17; P = 0.938). This difference between placebo and ascorbic acid was significant (P < 0.001). Plasma ascorbate concentrations decreased during hyperglycaemia and correlated directly with the reduction in the EFI (r = 0.798; P < 0.001). 4. Pretreatment with an intravenous bolus of ascorbic acid can prevent endothelial dysfunction during acute systemic hyperglycaemia. Therefore, ascorbic acid may have potential therapeutic use in clinical situations where acute hyperglycaemia may be a complication.

FFAs: do they play a role in vascular disease in the insulin resistance syndrome?

The insulin resistance syndrome, otherwise known as the metabolic syndrome, describes a cluster of cardiovascular and metabolic abnormalities, which are strongly associated with overweight and obesity. The importance of the syndrome is due to its increased rates of cardiovascular morbidity and mortality. Insulin resistance is also characterized by elevated free fatty acid (FFA) levels. In otherwise healthy human subjects, elevation of FFA impairs endothelial function. This appears to be largely the result of blunting of nitric oxide-dependent tone, most likely at the level of the endothelial isoform of nitric oxide synthase (eNOS). Some of the potential mediatory mechanisms include oxidative stress, proinflammatory cytokines, C-reactive protein, or endogenous inhibitors of eNOS. Regardless of the mechanism(s) that mediates the effects of increased FFA on the vasculature, impaired vascular function is likely to account, at least in part, for the increase in cardiovascular mortality in subjects with the insulin resistance syndrome.

Acute Effect of High-Fat Meal on Endothelial Function in Moderately Dyslipidemic Subjects

OBJECTIVE

Hypercholesterolemia markedly impairs endothelial function. Whether this is the case for hypertriglyceridemia is less clear, however, and limited evidence exists on the effect of an acute increase in triglyceridemia caused by a high-fat meal.

METHODS AND RESULTS

In 16 normotensive subjects with an untreated mild hypertriglyceridemia and dyslipidemia and in 7 normal controls, we measured radial artery diameter and blood flow by an echo-tracking device (NIUS02). Data were obtained at baseline, at the release of a 4-minute ischemia of the hand, which causes an increase in arterial diameter dependent on nitric oxide (NO) secretion, and at the release of a 12-minute exclusion of the arm by an arm cuff to obtain a larger increase in arterial diameter mainly of nonendothelial nature. Measurements were performed before and 6 hours after a high-fat meal (680 kcal/m(2) body surface; 82% lipids). In mild dyslipidemic hypertriglyceridemic subjects, the high-fat meal did not alter baseline blood pressure (beat-to-beat finger measurement), heart rate, radial artery diameter, and blood flow. It also did not alter the increase in blood flow induced by the 4-minute ischemia (+42.7+/-10.4 and +43.7+/-10.4 mL/min), whereas it markedly attenuated the concomitant increase in arterial diameter (+0.31+/-0.06 versus 0.13+/-0.06 mm; P<0.05). The alteration of the diameter response did not correlate with changes in total cholesterol, but it showed a significant correlation with the increase in serum triglycerides induced by high-fat meal (r=0.49, P<0.05). This attenuation was not seen in control subjects and in subjects in whom measurements were repeated after a 6-hour observation period. It was also not paralleled by an alteration of the endothelially independent response to a 12-minute ischemia whose larger effects on arterial diameter and blood flow were similar before and after the high-fat meal.

CONCLUSIONS

Endothelial function is markedly impaired by a high-fat meal that causes an acute hypertriglyceridemia. This impairment is evident in dyslipidemic patients with baseline hypertriglyceridemia but not in normotriglyceridemic controls. An oral fat load was administered to 55 HIV-positive and 10 HIV-negative individuals. Postprandial clearance of triglyceride-rich lipoproteins was delayed in HIV-positive individuals. Compared with HIV-positive subjects not on PIs, those taking PIs do not have increased postprandial triglyceride-rich lipoproteins but do have increased postprandial intermediate-density and low-density lipoproteins. Hypercholesterolemia impairs endothelial function, whereas the effect of hypertriglyceridemia is less clear. In normotensive subjects with an untreated hypertriglyceridemia and hypercholesterolemia, we measured endothelial function before and 6 hours after a high-fat meal. The results demonstrate that in moderately dyslipidemic patients, endothelial function is impaired by acute hypertriglyceridemia.

Cardiovascular risk factors for stable angina pectoris versus unheralded myocardial infarction

BACKGROUND

Ischemic heart disease can vary substantially in its clinical presentation. Some patients have acute myocardial infarction (MI) without any previous signs of myocardial ischemia, whereas other patients may have stable angina pectoris for years without periods of acute unstability. This study compared baseline risk factors between subjects in whom stable angina pectoris developed and subjects in whom unheralded fatal or nonfatal MI developed during the follow-up period.

METHODS

In 1970 to 1973, all 50-year-old men in Uppsala, Sweden, were invited to participate in a health survey aimed at identifying risk factors for cardiovascular disease. The present study is a nested case-control study of subjects who were free of coronary heart disease (CHD) at baseline and who then underwent revascularization (percutaneous transluminal coronary angioplasty or coronary artery bypass grafting) because of angina pectoris without preceding MI (n = 70) or in whom fatal or nonfatal MI developed without prior known CHD (n = 372) during the period until 1998.

RESULTS

In multivariate Cox proportional hazard models, low-density lipoprotein and high-density lipoprotein levels (protective) were significant independent risk factors for stable angina pectoris demanding revascularization, whereas smoking, diastolic blood pressure, serum proinsulin levels, and serum lipid levels were significant independent predictors of subsequent unheralded MI. When comparing hazard ratios (HR), significantly higher HR for diastolic blood pressure (1.40 vs 1.00, for 1 SD increase) and serum proinsulin (1.82 vs1.20, for 1 SD increase) were found in the group in which unheralded MI developed than in the group with stable angina pectoris.

CONCLUSIONS

Serum lipid levels were important risk factors for the development of both stable and acute coronary heart disease. In addition, proinsulin levels and blood pressure were independent predictors of unheralded MI only, which suggests that these factors are involved in thrombosis, plaque rupture, or both.