Endothelial dysfunction as an integrating index of the risk factor burden and genetic susceptibility is an early marker of atherothrombotic disease. Therefore, tremendous interest exists in its measurement and determination of the clinical utility of the evaluation of endothelial function. Different invasive and non-invasive techniques exist for exploring various aspects of the pathobiology of the endothelium. As endothelial dysfunction is a diffuse-systemic disorder, the peripheral arteries, because of their accessibility, represent the basis for assessment of endothelial dysfunction. Flow-mediated dilation (FMD) of the peripheral conduit arteries is one of the most widely used tests of endothelial function. FMD measures the endothelial vasomotor response during reactive hyperemia, but it does not provide information concerning the control of arterial tone at rest. A new technique, low-flow-mediated constriction (L-FMC), provides complementary information to that by FMD, quantifying the decrease in the forearm conduit artery diameter that occurs in response to the decrease in blood flow during occlusion. This indicated that the L-FMC response is not based on nitric oxide availability but it might be mediated by other substances, providing a coordinated effect of vasodilation and its inhibition; therefore, simultaneous determination of FMD and L-FMC may provide comprehensive information on vascular homeostasis. Peripheral arterial tonometry (PAT) evaluates pulse wave amplitude, which is linked to endothelial function. Like FMD, PAT has also been shown to be reduced in the presence of risk factors, as well as in patients with atherosclerosis; however, FMD of the brachial artery and PAT are very different methods for identification of the vascular reactivity of different arterial territories. FMD directly registers the dilation capability of the large-conduit artery, whereas PAT measures flow response hyperemia, which is related to the endothelial function of small arteries and to the endothelial function of the microcirculation. Therefore, this technique is mostly used for investigation of the functional capability of the microcirculation. Determination of venous endothelial dysfunction is more complicated and invasive and is less reproducible. Micro-invasive techniques such as the dorsal hand vein technique and radionuclide assessment of changes in volume of the legs provide limited information about venous endothelial health; however, as endothelial dysfunction is expected to be a systemic disorder affecting the complete circulatory system, determination of the endothelial function of peripheral arteries also gives insight into venous functional status.
Aim: This study tested the hypothesis that tacrolimus therapy limited left ventricular (LV) infarct and remodeling by suppressing the inflammatory response, oxidative stress and regulating the mitogen-activated protein kinase (MAPK) and Akt signaling pathways in an acute myocardial infarction (AMI) mini-pig model by ligating the left anterior descending coronary artery (LAD). Methods: Twelve male mini-pigs were equally randomized into AMI treated by saline (3.0 mL) (AMIS), and AMI treated by tacrolimus (0.5 mg) (AMIT). Thirty minutes after the procedure, intra-LAD injections were performed just beyond the ligation. Results: Inflammatory biomarkers at transcription or protein levels [matrix metalloproteinase (MMP9), plasminogen activator inhitor-1, tumor necrotic factor (TNF-α), nuclear factor (NF)-κB] and the cellular level (CD40+ cells) were markedly higher in AMIS than in AMIT animals (all p<0.001). Fibrosis biomarkers at the protein level (α-smooth muscle actin, transforming growth factor-β) and Sirius-red staining were notably higher in AMIS than in AMIT animals (all p<0.03). Antioxidant biomarkers at protein or transcription levels (heme oxygenase-1, quinone oxidoreductase-1, glutathione reductase, glutathione peroxidase) were significantly higher in AMIS than in AMIT animals (all p<0.01). Protein expressions of ERK1, p38 MAPK and Akt were markedly increased in AMIS compared to AMIT animals (all p<0.001). Significantly aggravated LV infarction and remodeling were noted in AMIS compared to AMIT animals, whereas LV ejection fraction was markedly decreased in AMIS compared to AMIT animals (all p<0.001). Conclusions: Intra-coronary administration of tacrolimus attenuated inflammation and MAPK signaling, limited infarct size, and preserved LV function.
Aim: Although high-density lipoprotein cholesterol (HDL-C) levels are inversely associated with cardiovascular risk, patients with elevated HDL-C also develop coronary artery disease (CAD) and cardiac events. We aimed to draw the clinical profile of CAD patients with elevated HDL-C and to assess the prognostic impact of elevated HDL-C. Methods: We prospectively examined 2322 patients (age 67±10 years, 79% male) with chronic CAD, defined by >50% coronary stenosis and/or previous myocardial infarction. Results: HDL-C levels were low (<35 mg/dL) in 736 patients (32%), normal (35-60 mg/dL) in 1464 (63%), and high (>60 mg/dL) in 122 (5%). Patients with elevated HDL-C were less frequently male (p<0.0001), smokers (p<0.0001), diabetic (p<0.0001), and obese (p<0.0015) than those with low or normal HDL-C, but were 3 and 5 years older, respectively (p<0.0001). During follow-up (median, 46 months) 143 patients died from cardiac causes and 80 developed a non-fatal infarction. Cardiac event-free survival was lower in patients with low compared to normal HDL-C (p<0.0001), but was not significantly different from that of patients with elevated HDL-C. The prognostic impact of low HDL-C was independent of age, sex, diabetes, LV function, extent of coronary stenoses, low density lipoprotein cholesterol, triglycerides, complete blood count, thyroid and renal function (p<0.0001). Conversely, the prognostic impact of elevated HDL-C disappeared (p>0.10) after adjustment for age. Conclusion: Patients with elevated HDL-C develop CAD and cardiac events as do those with low or normal HDL, but at a more advanced age.
Aim: The use of currently marketed drug-eluting stents presents safety concerns including increased late thrombosis, which is thought to result mainly from delayed endothelial healing effects (impaired re-endothelialization resulting in abnormal inflammation and fibrin deposition). We recently developed a bioabsorbable polymeric nanoparticle (NP)-eluting stent using a novel cationic electrodeposition technology. Statins are known to inhibit the proliferation of vascular smooth muscle cells (VSMC) and to promote vascular healing. We therefore hypothesized that statin-incorporated NP-eluting stents would attenuate in-stent stenosis without delayed endothelial healing effects. Methods: Among six marketed statins, pitavastatin (Pitava) was found to have the most potent effects on VSMC proliferation and endothelial regeneration in vitro. We thus formulated a Pitava-NP-eluting stent (20µg Pitava per stent). Results: In a pig coronary artery model, Pitava-NP-eluting stents attenuated in-stent stenosis as effectively as polymer-coated sirolimus-eluting stents (SES). At SES sites, delayed endothelial healing effects were noted, whereas no such effects were observed in Pitava-NP-eluting stent sites. Conclusion: Pitava-NP-eluting stents attenuated in-stent stenosis as effectively as SES without the delayed endothelial healing effects of SES in a porcine coronary artery model. This nanotechnology platform could be developed into a safer and more effective device in the future.
Aim: To assess the effect of low-(10 mg) or high-(80 mg) dose atorvastatin on carotid artery distensibility in patients with asymptomatic carotid artery disease using carotid magnetic resonance imaging. Methods: Eighteen patients underwent initial 2-dimensional ECG gated-phase contrast carotid MR imaging and off-line applanation tonometry for distensibility assessment before randomisation to receive low- or high-dose statins and this was repeated at 12 weeks. Phase and magnitude images from the 2-D phase contrast acquisitions were used for quantification of distensibility and compliance coefficients and were compared between the low- and high-dose statin groups. Results: Both groups were comparable with regards to their demographics, co-morbidities and baseline cholesterol levels. After 12 weeks of high-dose statin administration, a significant decrease in LDL (p=0.003) and CRP (p=0.03) was observed. At 12 weeks, the distensibility coefficient of the common and internal carotid artery was found to be significantly higher (with respect to baseline) in the high-dose group (p=0.004 and p=0.007, respectively). The compliance coefficient was likewise found to be raised in the high-dose group when compared with the low-dose group [common carotid (p=0.002), internal carotid (p=0.009)]. Conclusions: High-dose atorvastatin tends to reduce carotid arterial stiffness, as suggested by increased distensibility and compliance coefficients; however, these results need validation through large-scale trials to fully establish their possible use in clinical practice.
Aim: The aim of the current study was to investigate circulating adiponectin levels and their associated factors in young lean healthy Japanese women. Methods: We recruited 82 healthy Japanese women in their twenties and thirties with their body mass index <25 kg/m2, and performed anthropometric, sphygmomanometric, and laboratory examinations. Laboratory examinations included adiponectin levels, as well as lipid profiles, glucose, hemoglobin A1c, transaminase, and creatinine levels, from which the glomerular filtration rate was estimated (eGFR). Results: The median and interquartile range of circulating adiponectin levels were 8.1 (6.2-10.0) µg/ mL. HDL cholesterol levels and eGFR, but not the other examined clinical parameters, were significantly correlated with log-transformed adiponectin levels; their correlation coefficients were 0.323 (p<0.01) and −0.311 (p<0.01), respectively. Statistical significance was still observed even after adjustment for each other (both p= 0.02). In adjusted models, subjects with HDL cholesterol levels ≥80 mg/dL had 1.3 times higher adiponectin levels than those with 40-60 mg/dL, whereas eGFR ≥110 mL/min/1.73m2 and 60-90 mL/min/1.73m2 showed a 1.5-fold difference in adiponectin levels. Conclusions: Adiponectin levels of young lean healthy Japanese women had significant associations with HDL cholesterol levels and eGFR, even though their HDL cholesterol levels and eGFR were distributed within normal ranges. It seems important to take into account these two variables in evaluating adiponectin levels of these subjects, even if the two variables are within normal ranges.
Aim: Aspirin resistance (AR) is common in Chinese stroke patients taking antiplatelet medications; however, few studies have documented the role of cyclooxygenase (COX)-1 C50T and COX-2 G765C polymorphisms in AR. The aim of this study was to investigate the prevalence of AR in Chinese stroke patients and the relationships between AR and COX-1 C50T and COX-2 G765C polymorphisms, and to evaluate the effect of these polymorphisms on platelet response to aspirin. Methods: We prospectively enrolled 634 Chinese stroke patients. Platelet aggregation testing was performed before and after aspirin administration. The pre- and post-aspirin levels of 11-dehydrothromboxane B2 (11-dTxB2) were determined in urine samples. COX-1 C50T and COX-2 G765C genotypes were determined by a polymerase chain reaction-allelic restriction assay. Results: AR was detected in 129 patients (20.4%), aspirin semi-resistance (ASR) was detected in 28 patients (4.4%), and aspirin sensitivity (AS) was detected in 477 patients (75.2%). There was no association between COX-1 C50T or COX-2 G765C polymorphisms and ASR+AR. Aspirin could efficiently reduce 11-dTxB2 production by approximately 75%. In addition, platelet aggregation, both in response to arachidonic acid (AA) and adenosine 5’-diphosphate (ADP), was inhibited by more than 80% and 40%, respectively; however, the percentage reduction in platelet aggregation and 11-dTxB2 levels was not significantly different between the COX-1 C50T and COX-2 G765C genotypes (p＞0.05). Conclusions: There was no association between COX-1 C50T and COX-2 G765C polymorphisms and AR in Chinese stroke patients. In addition, COX-1 C50T and COX-2 G765C polymorphisms had no effect on the platelet response to aspirin.
Aim: Left ventricular (LV) thrombus is one of the risk factors for systemic thromboembolism. The aims of this study were to compare the long-term clinical outcomes of LV thrombus using current therapeutics, anticoagulation, operative treatment, and antiplatelet agents and to identify independent predictors of systemic thromboembolism. Methods: We screened 86,374 patients for intracardiac thrombus in the electronic medical records and imaging databases. Records of 62 patients with LV thrombus, diagnosed between May 2003 to November 2011, were comprehensively reviewed regarding baseline characteristics, imaging data and thrombus outcomes, thromboembolic events and treatment complications by treatment group. Results: The majority (80.6%) had ischemic etiology. Systemic thromboembolism developed in 18 patients; 8 (45%) were post-treatment thromboembolisms while 10 events occurred before treatment began. No post-treatment thromboembolism occurred in the operative treatment group; in contrast, 7 post-treatment thromboembolisms occurred in anticoagulation group (17%) (Log rank p= 0.175). Independent predictors of post-treatment thromboembolism were dilated cardiomyopathy (HR 61.30, p= 0.001), previous cerebrovascular events (HR 7.06, p= 0.042), female gender (HR 7.11, p= 0.031), and echocardiographic left ventricular end-diastolic diameter (HR 1.15, p= 0.047). Conclusions: In this study, the rate of post-treatment thromboembolism was not significantly different among the treatment groups; however, operative treatment tended towards less post-treatment thromboembolism than other treatment groups.
Aim: This study was to explore whether activating transcription factor 6 (ATF6), an important sensor to endoplasmic reticulum (ER) stress, would mediate oxidized low-density lipoprotein (ox-LDL)- induced cholesterol accumulation and apoptosis in cultured macrophages and the underlying molecular mechanisms. Methods: Intracellular lipid droplets and total cholesterol levels were assayed by oil red O staining and enzymatic colorimetry, respectively. Cell viability and apoptosis were determined using MTT assay and AnnexinV-FITC apoptosis detection kit, respectively. The nuclear translocation of ATF6 in cells was detected by immunofluorescence analysis. Protein and mRNA levels were examined by Western blot analysis and real time-PCR, respectively. ATF6 siRNA was transfected to RAW264.7 cells by lipofectamin. Results: Exposure of cells to ox-LDL induced glucose-regulated protein 78 (GRP78). C/EBP homologous protein (CHOP), a key-signaling component of ER stress-induced apoptosis, was up-regulated in ox-LDL-treated cells. ATF6, a factor that positively regulates CHOP expression, was activated by ox-LDL in a concentration- and time- dependent manner. The role of the ATF6-mediated ER stress pathway was further confirmed through the siRNA-mediated knockdown of ATF6, which attenuated ox-LDL-induced upregulation of CHOP, cholesterol accumulation and apoptosis in macrophages. In addition, the phosphorylation of double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase (PERK), another factor that positively regulates CHOP expression, was induced in the presence of ox-LDL, and PERK-specific siRNA also inhibited the ox-LDL-induced upregulation of CHOP and apoptosis in RAW264.7 cells. Conclusion: These results demonstrate that ER stress-related proteins, particularly ATF6 and its downstream molecule CHOP, are involved in ox-LDL-induced cholesterol accumulation and apoptosis in macrophages.
Aim: To evaluate the effect of statin therapy on the decrease of common carotid artery intima-media thickness (CCA-IMT) compared to placebo or usual care. Methods: A systematic search of electronic databases (MEDLINE, EMBASE, and Cochrane Center Register) up to December 2011 was performed. Two reviewers independently determined the eligibility of randomized controlled trials (RCTs) comparing statin therapy with a placebo or usual care with a minimum follow-up of 6 months. Results: Twenty-one RCTs involving 6317 individuals were included in this review. The pooled weighted mean difference (WMD) between statin therapy and placebo or usual care on CCA-IMT was −0.029 mm (95%CI: −0.045, −0.013). Subgroup analyses showed significant effects of lovastatin (WMD: −0.077; 95%CI: −0.082, −0.073) and simvastatin (WMD: −0.069; 95%CI: −0.094, −0.045), followed by pravastatin and rosuvastatin, but no significant benefits of atorvastatin, fluvastatin, or cerivastatin. A greater decrease in mean CCA-IMT was observed in the setting of secondary prevention versus primary prevention (WMD: −0.045 vs. −0.004), in younger patients versus older patients (WMD: −0.057 vs. −0.041), and in studies where the patient proportion was males ≥ females (−0.044 vs. −0.008). Meta-regression analysis showed a significant association between changes in mean CCA-IMT with decreasing triglyceride levels. A similar, but not statistically significant trend was also found between CCA-IMT decrease and the decrease in LDL-C levels or increase in HDL-C levels. Conclusion: Statin therapy is associated with a favorable decrease in CCA-IMT, an effect that seems to be mainly driven by the CCA-IMT at baseline and the extent of lipid decrease, specifically triglycerides.