FLAIR MRI biomarkers of the normal appearing brain matter are related to cognition.

A novel biomarker panel was proposed to quantify macro and microstructural biomarkers from the normal-appearing brain matter (NABM) in multicentre fluid-attenuation inversion recovery (FLAIR) MRI. The NABM is composed of the white and gray matter regions of the brain, with the lesions and cerebrospinal fluid removed. The primary hypothesis was that NABM biomarkers from FLAIR MRI are related to cognitive outcome as determined by MoCA score. There were three groups of features designed for this task based on 1) texture: microstructural integrity (MII), macrostructural damage (MAD), microstructural damage (MID), 2) intensity: median, skewness, kurtosis and 3) volume: NABM to ICV volume ratio. Biomarkers were extracted from over 1400 imaging volumes from more than 87 centres and unadjusted ANOVA analysis revealed significant differences in means of the MII, MAD, and NABM volume biomarkers across all cognitive groups. In an adjusted ANCOVA model, a significant relationship between MoCA categories was found that was dependent on subject age for MII, MAD, intensity, kurtosis and NABM volume biomarkers. These results demonstrate that structural brain changes in the NABM are related to cognitive outcome (with different relationships depending on the age of the subjects). Therefore these biomarkers have high potential for clinical translation. As a secondary hypothesis, we investigated whether texture features from FLAIR MRI can quantify microstructural changes related to how "structured" or "damaged" the tissue is. Based on correlation analysis with diffusion weighted MRI (dMRI), it was shown that FLAIR MRI texture biomarkers (MII and MAD) had strong correlations to mean diffusivity (MD) which is related to tissue degeneration in the GM and WM regions. As FLAIR MRI is routinely collected for clinical neurological examinations, novel biomarkers from FLAIR MRI could be used to supplement current clinical biomarkers and for monitoring disease progression. Biomarkers could also be used to stratify patients into homogeneous disease subgroups for clinical trials, or to learn more about mechanistic development of dementia disease.

Beneficial Effects of High-Density Lipoproteins on Acquired von Willebrand Syndrome in Aortic Valve Stenosis.

BACKGROUND: Infusions of apolipoprotein A-I (apoA-I), the major protein component of high-density lipoproteins (HDL), result in aortic valve stenosis (AVS) regression in experimental models. Severe AVS can be complicated by acquired von Willebrand syndrome, a haemorrhagic disorder associated with loss of high-molecular-weight von Willebrand factor (vWF) multimers (HMWM), the latter being a consequence of increased shear stress and enhanced vWF-cleaving protease (ADAMTS-13) activity. Although antithrombotic actions of HDL have been described, its effects on ADAMTS-13 and vWF in AVS are unknown. METHODS AND RESULTS: We assessed ADAMTS-13 activity in plasma derived from a rabbit model of AVS (n = 29) as well as in plasma collected from 64 patients with severe AVS (age 65.0 ± 10.4 years, 44 males) undergoing aortic valve replacement (AVR). In both human and rabbit AVS plasma, ADAMTS-13 activity was higher than that in controls (p < 0.05). Accordingly, AVS patients had less HMWM than controls (66.3 ± 27.2% vs. 97.2 ± 24.1%, p < 0.0001). Both ADAMTS-13 activity and HMWM correlated significantly with aortic transvalvular gradients, thereby showing opposing correlations (r = 0.3, p = 0.018 and r = -0.4, p = 0.003, respectively). Administration of an apoA-I mimetic peptide reduced ADAMTS-13 activity in AVS rabbits as compared with the placebo group (2.0 ± 0.5 RFU/sec vs. 3.8 ± 0.4 RFU/sec, p < 0.05). Similarly, a negative correlation was found between ADAMTS-13 activity and HDL cholesterol levels in patients with AVS (r = -0.3, p = 0.045). CONCLUSION: Our data indicate that HDL levels are associated with reduced ADAMTS-13 activity and increased HMWM. HDL-based therapies may reduce the haematologic abnormalities of the acquired von Willebrand syndrome in AVS.

Validation of fatty acid intakes estimated by a food frequency questionnaire using erythrocyte fatty acid profiling in the Montreal Heart Institute Biobank.

BACKGROUND: To improve the prevention, treatment and risk prediction of cardiovascular diseases, genetic markers and gene-diet interactions are currently being investigated. The Montreal Heart Institute (MHI) Biobank is suitable for such studies because of its large sample size (currently, n = 17 000), the availability of biospecimens, and the collection of data on dietary intakes of saturated (SFAs) and n-3 and n-6 polyunsaturated (PUFAs) fatty acids estimated from a 14-item food frequency questionnaire (FFQ). We tested the validity of the FFQ by correlating dietary intakes of these fatty acids with their red blood cell (RBC) content in MHI Biobank participants. METHODS: Seventy-five men and 75 women were selected from the Biobank. We successfully obtained RBC fatty acids for 142 subjects using gas chromatography coupled to mass spectrometry. Spearman correlation coefficients were used to test whether SFA scores and daily intakes (g day(-1)) of n-3 and n-6 PUFAs correlate with their RBC content. RESULTS: Based on covariate-adjusted analyses, intakes of n-3 PUFAs from vegetable sources were significantly correlated with RBC α-linolenic acid levels (ρ = 0.23, P = 0.007), whereas n-3 PUFA intakes from marine sources correlated significantly with RBC eicosapentaenoic acid (ρ = 0.29, P = 0.0008) and docosahexaenoic acid (ρ = 0.41, P = 9.2 × 10(-7)) levels. Intakes of n-6 PUFAs from vegetable sources correlated with RBC linoleic acid (ρ = 0.18, P = 0.04). SFA scores were not correlated with RBC total SFAs. CONCLUSIONS: The MHI Biobank 14-item FFQ can appropriately estimate daily intakes of n-3 PUFAs from vegetable and marine sources, as well as vegetable n-6 PUFAs, which enables the possibility of using these data in future studies.

Improvement of aortic valve stenosis by ApoA-I mimetic therapy is associated with decreased aortic root and valve remodelling in mice.

BACKGROUND AND PURPOSE: We have shown that infusions of apolipoprotein A-I (ApoA-I) mimetic peptide induced regression of aortic valve stenosis (AVS) in rabbits. This study aimed at determining the effects of ApoA-I mimetic therapy in mice with calcific or fibrotic AVS. EXPERIMENTAL APPROACH: Apolipoprotein E-deficient (ApoE(-/-) ) mice and mice with Werner progeria gene deletion (Wrn(Δhel/Δhel) ) received high-fat diets for 20 weeks. After developing AVS, mice were randomized to receive saline (placebo group) or ApoA-I mimetic peptide infusions (ApoA-I treated groups, 100 mg·kg(-1) for ApoE(-/-) mice; 50 mg·kg(-1) for Wrn mice), three times per week for 4 weeks. We evaluated effects on AVS using serial echocardiograms and valve histology. KEY RESULTS: Aortic valve area (AVA) increased in both ApoE(-/-) and Wrn mice treated with the ApoA-I mimetic compared with placebo. Maximal sinus wall thickness was lower in ApoA-I treated ApoE(-/-) mice. The type I/III collagen ratio was lower in the sinus wall of ApoA-I treated ApoE(-/-) mice compared with placebo. Total collagen content was reduced in aortic valves of ApoA-I treated Wrn mice. Our 3D computer model and numerical simulations confirmed that the reduction in aortic root wall thickness resulted in improved AVA. CONCLUSIONS AND IMPLICATIONS: ApoA-I mimetic treatment reduced AVS by decreasing remodelling and fibrosis of the aortic root and valve in mice.

Mannheim carotid intima-media thickness and plaque consensus (2004-2006-2011). An update on behalf of the advisory board of the 3rd, 4th and 5th watching the risk symposia, at the 13th, 15th and 20th European Stroke Conferences, Mannheim, Germany, 2004, Brussels, Belgium, 2006, and Hamburg, Germany, 2011.

Intima-media thickness (IMT) provides a surrogate end point of cardiovascular outcomes in clinical trials evaluating the efficacy of cardiovascular risk factor modification. Carotid artery plaque further adds to the cardiovascular risk assessment. It is defined as a focal structure that encroaches into the arterial lumen of at least 0.5 mm or 50% of the surrounding IMT value or demonstrates a thickness >1.5 mm as measured from the media-adventitia interface to the intima-lumen interface. The scientific basis for use of IMT in clinical trials and practice includes ultrasound physics, technical and disease-related principles as well as best practice on the performance, interpretation and documentation of study results. Comparison of IMT results obtained from epidemiological and interventional studies around the world relies on harmonization on approaches to carotid image acquisition and analysis. This updated consensus document delineates further criteria to distinguish early atherosclerotic plaque formation from thickening of IMT. Standardized methods will foster homogenous data collection and analysis, improve the power of randomized clinical trials incorporating IMT and plaque measurements and facilitate the merging of large databases for meta-analyses. IMT results are applied to individual patients as an integrated assessment of cardiovascular risk factors. However, this document recommends against serial monitoring in individual patients.

Determinants of masked hypertension in hypertensive patients treated in a primary care setting.

BACKGROUND: Recent data suggest that masked hypertension (MH) carries a cardiovascular risk similar to that of uncontrolled hypertension. AIMS: The objective of this study was to determine the prevalence and determinants of MH in patients treated for hypertension in a Canadian primary care setting. METHODS: Office blood pressure (OBP) was measured at baseline and after 3 months of valsartan-based therapy in 5636 hypertensive patients who had recorded their home blood pressure monitoring (HBPM) for seven consecutive days at month 3 using an Omron HEM-711 apparatus. MH was defined in nondiabetic patients as an OBP <140/90 mmHg and an HBPM ≥135/85 mmHg, and in those with diabetes as an OBP <130/80 mmHg and an HBPM ≥125/75 mmHg. RESULTS: Of the 5636 patients, 1025 had diabetes. OBP was controlled at 3 months in 268 (26.1%) of them, but 167 (62.3%) had MH. OBP was controlled in 2728 (59.1%) of the 4611 patients without diabetes, and 935 (34.3%) of them had MH. Overall, 1102 patients had MH, representing 36.8% of patients with controlled OBP and 19.6% of the entire hypertensive study population. Stepwise multiple logistic regression analysis in nondiabetic patients with controlled OBP at 3 months revealed that older age, male sex, higher body mass index and higher office systolic blood pressure were determinants of MH. CONCLUSION: Our results indicate that one of five hypertensive patients and more than one of three with controlled OBP will have MH. MH is associated with other cardiovascular risk factors, such as diabetes, and in nondiabetics, with male sex, older age and obesity.

Effects of fasting and/or postprandial glucose on heart rate recovery in patients with coronary heart disease.

AIM: The impact of both fasting and postprandial glycaemia on heart rate recovery (HRR) has not been studied in patients with coronary heart disease (CHD). For this reason, we sought to determine the relationships between HRR and both fasting and postprandial glycaemia. METHODS: A total of 4079 patients with baseline fasting plasma glucose (FPG) levels and 706 patients with 2-hour postprandial glucose (2hPG) levels were identified from the Coronary Artery Surgery Study registry, a database of 24,958 patients with suspected or proven CHD who had undergone cardiac catheterization between 1974 and 1979. Median long-term follow-up was 14.7 years (interquartile range: 9.8-16.2 years). The relationships between HRR and both FPG and 2hPG were studied. RESULTS: In univariate analyses, increasing levels of both FPG and 2hPG were significantly associated with lower HRR. In multivariate models adjusted for age, exercise tolerance in METs, resting heart rate and maximum systolic blood pressure during exercise testing, FPG remained significantly associated with HRR while 2hPG did not. CONCLUSION: Both raised FPG and decreased HRR are independent predictors of total and cardiovascular (CV) mortality in subjects with CHD. Our data suggest that the mortality risk associated with elevated FPG may in part be due to deleterious effects on autonomic regulation of CV function, as reflected by lower HRR. Further studies are required to determine whether or not non-pharmacological and/or pharmacological treatments of increased fasting glucose have a beneficial influence on HRR.

Informed consent in the context of pharmacogenomic research: ethical considerations.

Although the scientific research surrounding pharmacogenomics (PGx) has been relatively plentiful, the ethical research concerning this discipline has developed rather conservatively. Following investigation of the ethical, legal and social issues (ELSI) of PGx research, as well as consulting with key stakeholders, we identified six outstanding ethical issues raised by the informed consent process in PGx research: (1) scope of consent; (2) consent to 'add-on' studies; (3) protection of personal information; (4) commercialization; (5) data sharing; and (6) potential risks stemming from population-based research. In discussing these six areas as well as offering specific considerations, this article offers a solid base from which future practical guidelines for informed consent in PGx research can be constructed. As such, this effort works toward filling the ELSI gap and provides ethical support to the numerous PGx projects undertaken by researchers every year.

Effect of heart rate reduction by ivabradine on left ventricular remodeling in the echocardiographic substudy of BEAUTIFUL.

AIMS: Occlusive coronary artery disease (CAD) is associated with left ventricular (LV) remodeling, LV systolic dysfunction, and heart failure. The BEAUTIFUL Echo substudy aimed to evaluate the effects of heart rate reduction with ivabradine on LV size (primary end-point: change in LV end-systolic volume index [LVESVI]) and function and the cardiac biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP). METHODS AND RESULTS: The substudy was carried out in 86 centers participating in the BEAUTIFUL study. 2D echocardiography was performed at baseline, and after 3 and 12 months in patients with stable CAD and LV systolic dysfunction receiving ivabradine or placebo at the same time-points. All data were read and analyzed centrally. Of 525 patients completing the study, 426 had adequate echocardiographic readings (n = 220 ivabradine; n = 206 placebo). Treatment with ivabradine was associated with a decrease in the primary end-point LVESVI (change from baseline to last value, -1.48 ± 13.00 mL/m(2)) versus an increase with placebo (1.85 ± 10.54 mL/m(2)) (P=0.018). There was an increase in LV ejection fraction with ivabradine (2.00 ± 7.02%) versus no change with placebo (0.01 ± 6.20%) (P=0.009). Reduction in LVESVI was related to the degree of heart rate reduction with ivabradine. There were no differences in any other echocardiographic parameters or NT-proBNP. Change in LVESVI was related to the log change in NT-proBNP in the ivabradine group only (r = 0.18, P = 0.006). CONCLUSIONS: Our observations suggest that ivabradine may reverse detrimental LV remodeling in patients with CAD and LV systolic dysfunction.

Bosentan does not improve pulmonary hypertension and lung remodeling in heart failure.

Pulmonary hypertension (PH) and right ventricular (RV) dysfunction associated with heart failure (HF) carry a poor prognosis. Although endothelin receptor antagonists (ERAs) demonstrated benefits in pulmonary arterial hypertension, their efficacy in PH associated with HF was not specifically evaluated. 2 weeks after myocardial infarction (MI) rats received bosentan (100 or 200 mg·kg(-1)·day(-1)) or no treatment for 3 weeks. PH, RV hypertrophy and function as well as lung remodeling and function were evaluated. LV echocardiographic wall motion abnormality and function measured before treatment (2 weeks after MI) and after treatment (5 weeks after MI) were similar in MI control and MI treatment groups. HF induced PH and RV hypertrophy compared with sham: RV systolic pressure 39±5 versus 23±0.8 mmHg and RV/left ventricular+septum weight 52±7 versus 24±0.5% (all p<0.01). Bosentan did not significantly modify these parameters. In addition, bosentan did not improve depressed RV function measured by echocardiograph from the RV myocardial performance index and tricuspid annular plane systolic excursion. The respiratory pressure-volume relationship revealed that HF caused a restrictive lung syndrome with histological lung remodeling and fibrosis, also not improved by bosentan. Dual ERA therapy with bosentan does not reduce PH, RV hypertrophy and lung remodeling and dysfunction associated with ischaemic HF.

Deformable mock stenotic artery with a lipid pool.

The comparison, evaluation, and optimization of new techniques, models, or algorithms often require the use of realistic deformable test phantoms. The purpose of this paper is to present a multilayer deformable test specimen mimicking an atherosclerotic coronary artery, suitable for mechanical testing and intravascular imaging. Mock arteries were constructed in three phases using two molds: building a first layer of polyvinyl alcohol (PVA) cryogel, adding a lipid pool and building a second layer of PVA cryogel. To illustrate the deformation of the mock arteries, one has been placed in a custom-made bath, axially stretched then inflated while acquiring intravascular ultrasound (IVUS) images. The resulting specimen presents a progressing lumen narrowing of 25% in cross-sectional area at the peak and a lipid pool. The average inner gel layer is about 0.4 mm thick and the outer about 0.6 mm. The dimensions are of the same order as clinical observations, the first gel layer mimicking the intima-media and the second layer the adventitia. In the sequence of IVUS images, the different components of the mock artery are visible and differentiable. The variation in diameter of the segmented contours is presented for a specific specimen subjected to intraluminal pressure. This double-layer stenotic mock artery is approximately the size of a human coronary artery, has a lipid inclusion, can withstand relative large deformation, suitable for (intravascular) ultrasound imaging, and has customizable geometry and wall material parameters.

Glycaemic status influences the nature and severity of coronary artery disease.

AIMS/HYPOTHESIS: We sought to understand the relationships between glycaemic status and both severity and progression of coronary artery disease (CAD), the leading cause of death in diabetes. METHODS: Baseline fasting blood glucose (FBG) and HbA1c (%)were measured in 426 patients with known or suspected stable CAD, who underwent coronary artery intravascular ultrasound(IVUS) at baseline and after a mean follow-up period of 664 days (range 257 to 961). The patients were categorised as normoglycaemic (n=226, 53%), or as having impaired fasting glucose (n=118, 28%) or diabetes (n=82, 19%). RESULTS: The maximum percentage coronary atheroma area at baseline was greater in diabetic patients (73.33+/-8.86%) than in those with normoglycaemia (69.08+/-10.43%; p=0.001) and impaired fasting glucose (69.32+/-9.59%; p=0.0031). In averaged IVUS measurements of the 30-mm target segment(n=332 participants), change in percentage atheroma area during follow-up was also greater in the diabetes (1.86+/-3.90%) than in other groups (0.28+/-3.32% and 0.56+/-2.96%,p=0.0047 global). FBG correlated with maximum percentage atheroma area at baseline (r=0.17; p=0.0003). HbA1c also correlated with maximum percentage atheroma area at baseline (r=0.26; p=0.0001) and with change in maximum plaque area (r=0.16; p=0.016). A similar pattern of results occurred with plaque volume. The relationships between diabetes or HbA1c and both IVUS measurements of plaque burden and remodelling persisted after adjustment. CONCLUSIONS/INTERPRETATION: Fasting blood glucose, HbA1c and the presence of diabetes are associated with the severity and progression of coronary atherosclerosis. These observations support the hypothesis that better glycaemic control may favourably influence CAD in patients with abnormal glucose tolerance or diabetes.

Polyvinyl alcohol cryogel: optimizing the parameters of cryogenic treatment using hyperelastic models.

The PVA gels obtained by freezing/thawing cycles of PVA solutions, also called cryogels, exhibit non-linear elastic behavior and can mimic, within certain limits, the behavior of biological soft tissues such as arterial tissue. Several authors have investigated the effects of cryogenic processing parameters on the Young's modulus. However, an elastic modulus does not describe the non-linearity of the cryogel's stress-strain response. This study examines the non-linear elastic response of PVA cryogel under uniaxial tension and investigates how processing parameters such as the concentration, the number of thermal cycles, and the thawing rate affect this response. The relationship between the coefficients of the material model and the processing parameters was interpolated to find the set of parameters that would best approximate the elastic response of healthy porcine coronary arteries under uniaxial tension.

3D flow study in a mildly stenotic coronary artery phantom using a whole volume PIV method.

Blood flow dynamics has an important role in atherosclerosis initiation, progression, plaque rupture and thrombosis eventually causing myocardial infarction. In particular, shear stress is involved in platelet activation, endothelium function and secondary flows have been proposed as possible variables in plaque erosion. In order to investigate these three-dimensional flow characteristics in the context of a mild stenotic coronary artery, a whole volume PIV method has been developed and applied to a scaled-up transparent phantom. Experimental three-dimensional velocity data was processed to estimate the 3D shear stress distributions and secondary flows within the flow volume. The results show that shear stress reaches values out of the normal and atheroprotective range at an early stage of the obstructive pathology and that important secondary flows are also initiated at an early stage of the disease. The results also support the concept of a vena contracta associated with the jet in the context of a coronary artery stenosis with the consequence of higher shear stresses in the post-stenotic region in the blood domain than at the vascular wall.

Protective effect of pyridoxal-5-phosphate (MC-1) on perioperative myocardial infarction is independent of aortic cross clamp time: results from the MEND-CABG trial.

AIM: Aortic cross-clamp time remains a significant marker of mortality and morbidity after coronary artery bypass graft (CABG) surgery. Pyridoxal-5-phosphate (MC-1), blocking purinergic receptors and intracellular influx of calcium, was shown to decrease the incidence of perioperative myocardial infarction in the prospective, randomized, double-blinded MC-1 to Eliminate Necrosis and Damage in CABG (MEND-CABG) clinical trial. METHODS: We studied the relationship between treatment with MC-1 and aortic cross-clamping relative to the incidence of cardiovascular (CV) death and myocardial infarction (MI) in the trial that enrolled 901 high-risk patients undergoing CABG with cardiopulmonary bypass. Patients were randomized to receive either placebo, MC-1 250 mg/day or MC-1 750 mg/day starting 3-10 h before CABG and continued for 30 days after surgery. Serial creatine kinase-myocardial band (CK-MB) determinations, ECGs and clinical evaluations were performed. RESULTS: Cross-clamping time increased the event rate of death and MI with an odds ratio (95% confidence interval) of 1.67 (1.17-2.37, P=0.0044). Treatment with MC-1 decreased the rate of events (P=0.0073) with odds ratios of 0.52 (0.31-0.88 for MC-1 250 mg/day versus placebo) and 0.48 (0.29-0.82 for MC-1 750 mg/day versus placebo). There was no interaction between cross-clamp time and treatment (P=0.61) on the occurrence of the combined endpoint. CONCLUSION: MC-1 decreased the incidence of CV death and MI (CK-MB >or=100 ng/mL) during the first 90 days after CABG in the MEND-CABG trial. Although longer aortic clamping time increased the risk of cardiovascular events, the protective effect of MC-1 was independent of ischemic time during CABG.

Regression of aortic valve stenosis by ApoA-I mimetic peptide infusions in rabbits.

BACKGROUND AND PURPOSE: Aortic valve stenosis (AVS) is the most common valvular heart disease, and standard curative therapy remains open heart surgical valve replacement. The aim of our experimental study was to determine if apolipoprotein A-I (ApoA-I) mimetic peptide infusions could induce regression of AVS. EXPERIMENTAL APPROACH: Fifteen New Zealand White male rabbits received a cholesterol-enriched diet and vitamin D(2) until significant AVS was detected by echocardiography. The enriched diet was then stopped to mimic cholesterol-lowering therapy and animals were allocated randomly to receive saline (control group, n=8) or an ApoA-I mimetic peptide (treated group, n=7), three times per week for 2 weeks. Serial echocardiograms and post mortem valve histology were performed. KEY RESULTS: Aortic valve area increased significantly by 25% in the treated group after 14 days of treatment (P=0.012). Likewise, aortic valve thickness decreased by 21% in the treated group, whereas it was unchanged in controls (P=0.0006). Histological analysis revealed that the extent of lesions at the base of valve leaflets and sinuses of Valsalva was smaller in the treated group compared with controls (P=0.032). The treatment also reduced calcification, as revealed by the loss of the positive relationship observed in the control group (r=0.87, P=0.004) between calcification area and aortic valve thickness. CONCLUSIONS AND IMPLICATIONS: Infusions of ApoA-I mimetic peptide lead to regression of experimental AVS. These positive results justify the further testing of high-density lipoprotein (HDL)-based therapies in patients with valvular aortic stenosis. Regression of aortic stenosis, if achieved safely, could transform the clinical treatment of this disease.

Chronic heart rate reduction by ivabradine prevents endothelial dysfunction in dyslipidaemic mice.

BACKGROUND AND PURPOSE: High resting heart rate is a predictor for total and cardiovascular mortality independent of other risk factors in patients with coronary artery disease. We tested the hypothesis that a reduction of resting heart rate with the cardiac pacemaker I(f) current inhibitor ivabradine prevents the endothelial dysfunction associated with dyslipidaemia. EXPERIMENTAL APPROACH: Three-month-old dyslipidaemic (DL) male mice expressing the human ApoB-100 were assigned or not (DL, n=16), to treatment for 3 months with ivabradine (10 mg kg(-1) d(-1), n=17). Wild-type C57Bl/6 mice (WT, n=15) were used as controls. Heart rate was measured at 3, 4.5 and 6 months. Dilatation to acetylcholine (ACh) of isolated cerebral and renal arteries was investigated at 6 months. KEY RESULTS: Heart rate remained stable in anaesthetized WT mice, increased (25%, P<0.05) with age in DL mice but was limited (11%, P<0.05) by ivabradine. At 6 months, left ventricular maximal pressure was similar in all groups. The minimal and end-diastolic left ventricular pressures were increased (P<0.05) in DL (10.2+/-1.0 and 18.7+/-1.4 mm Hg) compared to WT (-0.4+/-0.7 and 6.3+/-1.0 mm Hg) and reduced (P<0.05) by ivabradine (4.2+/-1.3 and 11.5+/-1.5 mm Hg). ACh-induced maximal dilatation was impaired (P<0.05) in renal and cerebral arteries isolated from DL compared to WT (56+/-7 versus 83+/-3% in renal arteries; 22+/-2 versus 42+/-2% in cerebral arteries). Ivabradine completely prevented (P<0.05) this dysfunction in renal and cerebral arteries. CONCLUSIONS AND IMPLICATIONS: Selective heart rate reduction with ivabradine limits cardiac dysfunction and prevents the renovascular and cerebrovascular endothelial dysfunction associated with dyslipidaemia.

Lipoic acid supplementation and endothelial function.

Endothelial dysfunction is caused by all the recognized cardiovascular risk factors and has been implicated in the complex processes leading to the initiation and progression of atherosclerosis. Short-term treatment with lipoic acid is shown in the current issue of the British Journal of Pharmacology to improve endothelial function of aortic rings of old rats. The age-related decrease in phosphorylation of nitric oxide synthase and Akt was improved by lipoic acid supplementation. The improved phosphorylation status may have been due to reduced activity of the phosphatase PPA2, associated with decreased levels of endothelial ceramide induced by lipoic acid. Neutral sphingomyelinase activity was also reduced by lipoic acid, which was due, at least in part, to increased glutathione levels in endothelial cells. The favourable antioxidant, anti-inflammatory, metabolic and endothelial effects of lipoic acid shown in rodents, in this and other recently published studies, warrant further assessment of its potential role for prevention and treatment of cardiovascular diseases.

Does membrane fatty acid composition modulate mitochondrial functions and their thermal sensitivities?

We investigated the effect of modifying fatty acid modification of heart mitochondrial membranes by dietary intervention on the functions and thermal sensitivity of electron transport system complexes embedded in the inner mitochondrial membrane. Four groups of rats were fed diets differing in their fat (coconut, olive or fish oil) and antioxidant (fish oil with or without probucol) contents. After 16 weeks of feeding, the coconut and olive oil groups had lower long-chain n-3 polyunsaturated fatty acids contents and a lower unsaturation index compared to both fish oil groups. These differences in fatty acid composition were not related to any differences in the mitochondrial respiration rate induced at Complexes I, II or IV, or to differences in their thermal sensitivity. The coconut oil group showed a lower mitochondrial affinity for pyruvate at 5 degrees C (k(mapp)=6.4+/-1.8) compared to any other groups (k(mapp)=3.8+/-0.5; 4.7+/-0.8; 3.6+/-1.1, for olive, fish oil and fish oil and probucol groups, respectively). At least in rat heart, our results do not support a major impact of the fatty acid composition of the mitochondrial membrane on the function of mitochondrial enzymatic complexes or on their temperature sensitivity.