Homocysteine is a novel risk factor for suboptimal response of blood platelets to acetylsalicylic acid in coronary artery disease: A randomized multicenter study

Construction of a Prediction Model for Post-thrombotic Syndrome after Deep Vein Thrombosis Incorporating Novel Inflammatory Response Parameter Scoring

OBJECTIVE

To investigate the independent predictive factors for post-thrombotic syndrome (PTS) and to construct a risk prediction model for PTS by incorporating a novel inflammatory response parameter (NPM score) scoring.

METHODS

A retrospective study analyzed patients diagnosed with lower extremity deep vein thrombosis (LEDVTs at the Affiliated Hospital of Chengde Medical College from January 2018 to January 2022. The Villalta scale was used to assess the occurrence of PTS 6-24 months after discharge. Patients were randomly divided into a training set and a validation set at a ratio of 7:3. In the training set, univariate analysis was performed on meaningful continuous variables, and those with differences were converted into dichotomous variables based on optimal cutoff values. Variable selection was performed using Log Lambda and Least Absolute Shrinkage and Selection Operator 10-fold cross-validation, followed by multivariable logistic regression analysis on selected variables for model construction. The model underwent internal validation in the validation set and external validation in an independent external cohort, including discriminative analysis, calibration analysis, and clinical decision curve analysis (DCA), with the model's rationale being evaluated lastly.

RESULTS

A total of 356 patients with lower extremity DVT were included, with 249 in the training set for model construction and 107 in the validation set for internal validation, along with 37 external patients for external validation. A composite score of inflammatory response parameters, including the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and monocyte to high-density lipoprotein cholesterol ratio (MHR) (NLR-PLR-MHR score, NPM score), was developed, showing a significantly higher NPM score in the PTS group compared to the non-PTS group (P < 0.05). Predictive factors related to the risk of PTS occurrence included staging (OR = 6.83, 95% CI: 2.74-18.04), varicose veins (OR = 7.30, 95% CI: 2.29-25.75), homocysteine (Hcy) (OR = 1.12, 95% CI: 1.04-1.22), NPM score (OR = 3.13, 95% CI: 1.94-5.36), standardized anticoagulant therapy (OR = 5.77, 95% CI: 1.25-27.62), and one-stop treatment (OR = 0.04, 95% CI: 0.00-0.35) were incorporated into the Nomogram model. The model showed good discrimination with a concordance index of 0.918 (95% CI: 0.876-0.959) for model construction, 0.843 (95% CI: 0.741-0.945) for internal validation, and 0.823 (95% CI: 0.667-0.903) for external validation. In the Nomogram model, internal and external validation calibration curves showed good agreement between observed and predicted values. DCA indicated that the Nomogram model predicted PTS risk probability thresholds ranging from 3% to 98% for model construction, 5%-97% for internal validation, and 10%-80% for external validation, demonstrating better net benefit for predicting PTS risk in the model, internal, and external validation. Rationality analysis showed the model and internal validation had higher discrimination and clinical net benefit than other clinical indices.

CONCLUSIONS

The NPM score combined with stage, varicose veins, Hcy, standardized anticoagulant therapy, and one-stop treatment in the Nomogram model provides a practical tool for health care professionals to assess the risk of PTS in DVT patients, enabling early identification of high-risk patients for effective PTS prevention.

Protective effect and mechanism of procyanidin B2 against hypoxic injury of cardiomyocytes

Background

Cardiomyocyte ischemia and hypoxia are important causes of oxidative stress damage and cardiomyocyte apoptosis in coronary heart disease (CHD). Epidemiological investigation has shown that eating more plant-based foods, such as vegetables and fruits, may significantly decrease the risk of CHD. As natural antioxidants, botanicals have fewer toxic side effects than chemical drugs and have great potential for development. Procyanidin B2 (PB2) is composed of flavan-3-ol and epicatechin and has been reported to have antioxidant and anti-inflammatory effects. However, whether PB2 exerts protective effects on hypoxic cardiomyocytes has remained unclear. This study aimed to explore the protective effect of PB2 against cardiomyocyte hypoxia and to provide new treatment strategies and ideas for myocardial ischemia and hypoxia in CHD.

Methods and results

A hypoxic cardiomyocyte model was constructed, and a CCK-8 assay proved that PB2 had a protective effect on cardiomyocytes in a hypoxic environment. DCFH fluorescence staining, DHE staining, and BODIPY lipid oxidation assessment revealed that PB2 reduced the oxidative stress levels of cardiomyocytes under hypoxic conditions. TUNEL staining, Annexin V/PI fluorescence flow cytometry, and Western blot analysis of the expression of the apoptosis marker protein cleaved caspase-3 confirmed that PB2 reduced cardiomyocyte apoptosis under hypoxic conditions. JC-1 staining indicated that PB2 reduced the mitochondrial membrane potential of cardiomyocytes under hypoxia. In addition, transcriptomic analysis proved that the expression of 158 genes in cardiomyocytes was significantly changed after PB2 was added during hypoxia, of which 53 genes were upregulated and 105 genes were downregulated. GO enrichment analysis demonstrated that the activity of cytokines, extracellular matrix proteins and other molecules was changed significantly in the biological process category. KEGG enrichment analysis showed that the IL-17 signaling pathway and JAK-STAT signaling pathway underwent significant changes. We also performed metabolomic analysis and found that the levels of 51 metabolites were significantly changed after the addition of PB2 to cardiomyocytes during hypoxia. Among them, 39 metabolites exhibited increased levels, while 12 metabolites exhibited decreased levels. KEGG enrichment analysis showed that cysteine and methionine metabolism, arginine and proline metabolism and other metabolic pathways underwent remarkable changes.

Conclusion

This study proves that PB2 can reduce the oxidative stress and apoptosis of cardiomyocytes during hypoxia to play a protective role. Transcriptomic and metabolomic analyses preliminarily revealed signaling pathways and metabolic pathways that are related to its protective mechanism. These findings lay a foundation for further research on the role of PB2 in the treatment of CHD and provide new ideas and new perspectives for research on PB2 in the treatment of other diseases.

The amino acid content in the daily diet of seniors negatively correlates with the degree of platelet aggregation in a sex- and agonist-specific manner

Aging is a significant risk factor for the development of thrombotic diseases, dependent on blood platelet reactivity. However, the risk of thrombosis also appears to be significantly modulated by dietary nutrient content.

The aim of the current study was to assess the relationship between the amount of amino acids present in the daily diet (not supplemented) and the reactivity of blood platelets to arachidonate, collagen and ADP in 246 women and men aged 60–65 years.

Platelet reactivity was tested using whole blood impedance aggregometry. Amino acid intake was assessed with a 24-hour Recall Questionnaire and calculated with Dieta 5.0 software.

Older subjects receiving higher amounts of all essential amino acids with their daily diet exhibit significantly lower platelet responsiveness to AA-, COL- and ADP in a sex-specific manner: dietary amino acid content was more closely associated with AA- and, to some extent, ADP-induced platelet reactivity in women, and with COL-induced platelet aggregability in men. Therefore, dietary amino acid content may be a novel factor responsible for attenuating platelet reactivity in a sex- and agonist-specific manner.

The binding of autotaxin to integrins mediates hyperhomocysteinemia-potentiated platelet activation and thrombosis in mice and humans

Hcy increases integrin αIIbβ3 activation by promoting phospholipid hydrolysis and ATX interaction in platelets.

Targeting ATX-mediated integrin αIIbβ3 activation alleviates HHcy-potentiated thrombosis.

Hyperhomocysteinemia (HHcy) is associated with an exaggerated platelet thrombotic response at sites of vascular injury. In this study, human medical examination showed that elevated human plasma Hcy levels correlated positively with enhanced blood coagulation and platelet activity, suggesting that humans with HHcy are more prone to thrombus formation at the sites of vascular injury. Accordingly, we observed accelerated platelet activation, primary hemostasis, and thrombus formation in apolipoprotein E-deficient (ApoE^−/−) mice with acute or chronic HHcy. Upon homocysteine (Hcy) administration in C57BL/6J mice, platelet aggregation, spreading and clot retraction were markedly induced. More important, Hcy increased the affinity of platelet integrin αIIbβ3 with ligands and enhanced integrin outside-in signaling by promoting membrane phosphatidylserine exposure in vitro. Mechanistically, lipidomics analysis showed that lysophosphatidylcholines were the primary metabolites leading to clustering of HHcy-stimulated platelets. Cytosolic phospholipase A2 (cPLA2) activity and autotaxin (ATX, a secreted lysophospholipase D) secretion were upregulated by Hcy, leading to membrane phospholipid hydrolysis and PS exposure. Moreover, secreted ATX directly interacted with integrin β3. Inhibitors of cPLA2 and ATX activity blocked integrin αIIbβ3 outside-in signaling and thrombosis in HHcy ApoE^−/− mice. In this study, we identified a novel mechanism by which HHcy promotes platelet membrane phospholipid catabolism and extracellular ATX secretion to activate integrin outside-in signaling, consequently exacerbating thrombosis and the results revealed an innovative approach to treating HHcy-related thrombotic diseases.

Impact of Calcium Channel Blockers on Aspirin Reactivity in Patients with Coronary Artery Disease

PURPOSE

Calcium channel blockers (CCBs) do not reduce the risk of initial or recurrent myocardial infarction (MI) in patients diagnosed with stable coronary artery disease (CAD). The aim of this current study was to evaluate the association between CCBs and aspirin resistance in patients with CAD.

METHODS

Patients with stable CAD who were regularly taking aspirin (75-100 mg qd) for at least 1 month prior to enrollment in the study were included. The VerifyNow system was used for platelet function testing with high on-aspirin platelet reactivity (HAPR) defined as aspirin reaction units (ARU) >550. We compared patients treated with CCBs versus control group.

RESULTS

Five hundred three patients with CAD were included in this study, and 88 were treated with CCBs. Mean age (67.9±9.7 in the CCB group vs. 66.5±11.4 in the control group), gender (77.3 male vs. 82.9%), rates of diabetes mellitus (34.7 vs. 36.9%), rates of CKD (23.5 vs. 23.5%), dyslipidemia (85.1 vs. 85.3%), and statin therapy (89.5 vs. 90.7%) were similar. The mean ARU was 465.4±70.0 for patients treated with CCBs versus 445.2±60.0 in controls (p=0.006). Similarly, 15.9% of CCB patients demonstrated HAPR compared to 7.0% (p=0.006). The administration of CCBs was independently associated with HAPR in a multivariate analysis (OR 1.72, 95% CI: 1.04-8.91, p=0.047) as well as in propensity score matched analysis (OR 1.56; CI: 1.22-1.93; p<0.001).

CONCLUSIONS

Usage of CCBs is positively correlated with aspirin resistance. These findings may suggest an adverse pharmacologic effect of CCBs among patients with stable CAD treated with aspirin.

Impact of renin angiotensin system inhibitors on homocysteine levels and platelets reactivity in patients on dual antiplatelet therapy

BACKGROUND AND AIMS

Dual antiplatelet therapy (DAPT) and Renin-angiotensin system inhibitors (RASi) represent the cornerstone in the treatment of patients undergoing percutaneous coronary interventions (PCI), mainly after an acute ischemic event. However, high-on treatment residual platelet reactivity (HRPR), is not infrequent despite optimal medical treatment. Homocysteine (Hcy) is a metabolite of methionine catabolism linked to atherothrombosis. Recently, a potential crosstalk between RAS and Hcy has been suggested, potentially favouring platelet aggregation and cardiovascular disease.Therefore, we aimed to investigate the impact of RASi on Hcy levels and platelet aggregation in patients on DAPT after PCI.

METHODS AND RESULTS

Patients undergoing PCI on DAPT with ASA plus an ADP-antagonist (clopidogrel, ticagrelor or prasugrel), were included. RASi comprised angiotensin converting enzyme inhibitors (ACEi) and angiotensin receptor blockers (ARB). Aggregation tests were performed by Multiple Electrode Aggregometry. We included 1210 patients, of whom 862 (71.2%) were on treatment with RASi. Overall, DAPT composition was ASA+clopidogrel in 566 (46.8%) patients, ASA+ticagrelor in 428 (35.4%) and ASA+prasugrel in 216 (17.9%). Median values of Hcy were higher in RASi patients (p = 0.006), who displayed a higher percentage of Hcy above the median value (52.4% vs. 44.8%, p = 0.019, adjustedOR [95%CI] = 1.40 [1.04-1.88], p = 0.027). No differences in HRPR rate were found according to RASi use for ASPI test (3.6% vs. 3.3%, p = 0.88) and ADP test (25.6% vs. 24.3%,p = 0.62; adjustedOR [95%CI] = 1.23 [0.89-1.70], p = 0.220) and according to ADP-antagonist type. A direct linear relationship was observed between platelet reactivity and Hcy in both patients receiving RASi and untreated ones, with higher values of platelet aggregation being observed in patients with Hcy above the median, independently from RASi administration and DAPT strategy.

CONCLUSION

In patients on DAPT after PCI, RASi treatment did not emerge as an independent predictor of HRPR. However, the levels of Hcy were significantly elevated in patients on RASi and related to higher values of platelet reactivity, independently from the DAPT strategy.

Perioperative changes of response to antiplatelet medication in vascular surgery patients

Introduction

Reduced antiplatelet activity of aspirin (ALR) or clopidogrel (CLR) is associated with an increased risk of thromboembolic events. The reported prevalence data for low-responders vary widely and there have been few investigations in vascular surgery patients even though they are at high risk for thromb-embolic complications. The aim of this prospective observational monocentric study was to elucidate possible changes in ALR or CLR after common vascular procedures.

Methods

Activity of aspirin and clopidogrel was measured by impedance aggregometry using a multiple electrode aggregometer (Multiplate®). Possible risk factors for ALR or CLR were identified by demographical, clinical data and laboratory parameters. In addition, a follow-up aggregometry was performed after completion of the vascular procedure to identify changes in antiplatelet response.

Results

A total of 176 patients taking antiplatelet medications aspirin and/or clopidogrel with peripheral artery disease (PAD) and/or carotid stenosis (CS) were included in the study. The prevalence of ALR was 13.1% and the prevalence of CLR was 32% in the aggregometry before vascular treatment. Potential risk factors identified in the aspirin group were concomitant insulin medication (p = 0.0006) and elevated C-reactive protein (CRP) (p = 0.0021). The overall ALR increased significantly postoperatively to 27.5% (p = 0.0006); however, there was no significant change in CLR that was detected. In a subgroup analysis elevation of the platelet count was associated with a post-procedure increase of ALR incidence.

Conclusion

The incidence of ALR in vascular surgery patients increases after vascular procedures. An elevated platelet count was detected as a risk factor. Further studies are necessary to analyse this potential influence on patency rates of vascular reconstructions.

Homocysteine levels and platelet reactivity in coronary artery disease patients treated with ticagrelor

BACKGROUND AND AIM

Recurrent atherothrombotic events have been reported in certain higher risk subsets of patients even with ticagrelor, a potent first-line antiplatelet agent for the management of patients with acute coronary syndrome (ACS). Hyperhomocysteinemia is a known determinant of platelet function abnormalities. Therefore, the aim of our study was to evaluate the impact of homocysteine (Hcy) levels on platelet reactivity in patients receiving Ticagrelor.

METHODS AND RESULTS

Patients with ACS undergoing percutaneous coronary revascularization and on dual antiplatelet therapy with ASA + Ticagrelor (90mg/twice a day) were scheduled for platelet function assessment 30-90 days post-discharge. Aggregation tests were performed by Multiple Electrode Aggregometry (MEA). Suboptimal platelet inhibition HRPR-high residual platelet reactivity was defined if above the lower limit of normality (417 AU*min). We included 432 patients, divided according to Hcy tertiles. Higher Hcy levels were associated with age, renal failure, creatinine levels and use diuretics (p < 0.001). Patients with higher Hcy levels displayed a higher platelet reactivity at COL test (p = 0.002), and ADP test (p = 0.04), with a linear relationship between Hcy and platelet aggregation after stimulation with collagen (r = 0.202, p < 0.001), thrombin receptor peptide (r = 0.104, p = 0.05) and ADP (r = 0.145, p = 0.006). However, Hcy levels did not significantly affect the rate of HRPR with Ticagrelor (9.9% vs 13.7% vs 10.7%, p = 0.89; adjusted OR [95% CI] = [0.616-1.51], p = 0.99).

CONCLUSIONS

Among patients with ACS, despite the elevated platelet reactivity associated to hyperhomocysteinemia, DAPT with ticagrelor could overcome such phenomenon, achieving an adequate platelet inhibition in the majority of the patients.

Homocysteine Level Predicts Response to Dual Antiplatelet in Women With Minor Stroke or Transient Ischemic Attack: Subanalysis of the CHANCE Trial

OBJECTIVES

To investigate the relationship of homocysteine levels with the efficacy and safety of dual antiplatelet therapy in female and male patients. Approach and Results: The CHANCE trial (Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events) randomized patients with acute minor ischemic stroke or high-risk transient ischemic attack to clopidogrel plus aspirin or aspirin alone from October 1, 2009, to July 30, 2012, in China. A subgroup of 3044 consecutive patients with baseline homocysteine levels from 73 (64%) prespecified clinical sites was analyzed. Participants were grouped by sex. Primary outcome was stroke recurrence within 90 days. Secondary outcomes consisted of composite vascular events and independent living or death. Safety outcome was any bleeding. Cox proportional-hazards models were used to assess the interaction of homocysteine levels with randomized antiplatelet therapy on efficacy and safety outcomes. A significant interaction between homocysteine levels and the randomized antiplatelet therapies was found on recurrent stroke after adjustment for confounding factors in women (P=0.010) but not in men (P=0.595). Compared with aspirin alone, clopidogrel plus aspirin significantly reduced the risk of recurrent stroke in women without elevated homocysteine levels (adjusted hazard ratio, 0.459 [95% CI, 0.271-0.776]; P=0.004). Such benefit disappeared in female patients with increased homocysteine level. No significant interaction on functional outcome or bleeding rate was observed.

CONCLUSIONS

Homocysteine could be a potential biomarker to discriminate the effects of dual and single antiplatelet therapy in female patients with minor ischemic stroke or high-risk transient ischemic attack.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00979589.

Testosterone and dihydrotestosterone reduce platelet activation and reactivity in older men and women

The cardiovascular effects of testosterone and dihydrotestosterone are generally attributed to their modulatory action on lipid and glucose metabolism. However, no ex vivo studies suggest that circulating androgen levels influence the activation and reactivity of blood platelets - one of the main components of the haemostasis system directly involved in atherosclerosis. The levels of testosterone, dihydrotestosterone and oestradiol in plasma from men and women aged from 60 to 65 years were measured by LC-MS; the aim was to identify any potential relationships between sex steroid levels and the markers of platelet activation (surface membrane expression of GPII/IIIa complex and P-selectin) and platelet reactivity in response to arachidonate, collagen or ADP, monitored with whole blood aggregometry and flow cytometry. The results of the ex vivo part of the study indicate that the concentrations of testosterone and its reduced form, dihydrotestosterone are significantly negatively associated with platelet activation and reactivity. These observations were confirmed in an in vitro model: testosterone and dihydrotestosterone significantly inhibited platelet aggregation triggered by arachidonate or collagen. Our findings indicate that testosterone and dihydrotestosterone are significant haemostatic steroids with inhibitory action on blood platelets in older people.

Evaluation of platelet distribution width in hypertension with hyperhomocysteinemia

An increased platelet distribution width (PDW) value has been found in various cardiovascular diseases. The objective of this study was to evaluate the association between the PDW and hypertension with hyperhomocysteinemia in an elderly cohort. We performed a cross-sectional analysis among 2,685 elderly individuals who underwent hematological testing and blood pressure assessment. Individuals were divided according to the PDW quartiles. An unconditional multiple logistic regression analysis was used to determine the association between PDW and hypertension with hyperhomocysteinemia, after adjustments for gender, age, drinking status, creatinine levels, glucose levels, uric acid levels, triglyceride levels, platelet counts and body mass index. Homocysteine was observed to steadily and remarkably increase in the PDW quartiles. The PDW values of the hypertension with hyperhomocysteinemia group were significantly greater than the PDW values in the hypertension without hyperhomocysteinemia group or the normotension group. The PDW levels were associated with hypertension and hyperhomocysteinemia independently of the previously mentioned risk factors, and the odds ratio of the hypertension with hyperhomocysteinemia group was steadily and remarkably increased, by as much as two-fold, in the fourth quartile vs. the first quartile. In this elderly population-based cohort, elevated PDW levels were independently associated with hypertension and hyperhomocysteinemia, which may indicate that hypertension and hyperhomocysteinemia can induce platelet activation.

Platelet and Red Blood Cell Counts, as well as the Concentrations of Uric Acid, but Not Homocysteinaemia or Oxidative Stress, Contribute Mostly to Platelet Reactivity in Older Adults

Purpose

The goal of this study was to estimate the hierarchical contribution of the most commonly recognized cardiovascular risk factors associated with atherogenesis to activation and reactivity of blood platelets in a group of men and women at ages 60-65.

Methods

Socioeconomic and anthropometric data were taken from questionnaires. Blood morphology and biochemistry were measured with standard diagnostic methods. Plasma serum homocysteine was measured by immunochemical method. Plasma concentrations of VCAM, ICAM, total antioxidant status, and total oxidant status were estimated with commercial ELISA kits. Markers of oxidative stress of plasma and platelet proteins (concentrations of protein free thiol and amino groups) and lipids (concentrations of lipid peroxides) and generation of superoxide anion by platelets were measured with colorimetric methods. Platelet reactivity was estimated by impedance aggregometry with arachidonate, collagen, and ADP as agonists. Expression of selectin-P and GPIIb/IIIa on blood platelets was tested by flow cytometry.

Results

Platelet aggregation associated significantly negatively with HGB and age and significantly positively with PLT, MPV, PCT, PDW, and P-LCR. When platelet reactivity (“cumulative platelet reactivity_aggregation”) was analyzed in a cumulated manner, the negative association with serum concentration of uric acid (R_s = −0.169, p = 0.003) was confirmed. Multivariate analysis revealed that amongst blood morphological parameters, platelet count, plateletcrit, and number of large platelets and uric acid are the most predictive variables for platelet reactivity.

Conclusions

The most significant contributors to platelet reactivity in older subjects are platelet morphology, plasma uricaemia, and erythrocyte morphology.

Complex roles of the old drug aspirin in cancer chemoprevention and therapy

The nonsteroidal anti-inflammatory agent aspirin is widely used for preventing and treating cardiovascular and cerebrovascular diseases. In addition, epidemiologic evidences reveal that aspirin may prevent a variety of human cancers, while data on the association between aspirin and some kinds of cancer are conflicting. Preclinical studies and clinical trials also reveal the therapeutic effect of aspirin on cancer. Although cyclooxygenase is a well-known target of aspirin, recent studies uncover other targets of aspirin and its metabolites, such as AMP-activated protein kinase, cyclin-dependent kinase, heparanase, and histone. Accumulating evidence demonstrate that aspirin may act in different cell types, such as epithelial cell, tumor cell, endothelial cell, platelet, and immune cell. Therefore, aspirin acts on diverse hallmarks of cancer, such as sustained tumor growth, metastasis, angiogenesis, inflammation, and immune evasion. In this review, we focus on recent progress in the use of aspirin for cancer chemoprevention and therapy, and integratively analyze the mechanisms underlying the anticancer effects of aspirin and its metabolites. We also discuss mechanisms of aspirin resistance and describe some derivatives of aspirin, which aim to overcome the adverse effects of aspirin.

Correlation of hyper-homocysteinemia with coronary artery disease in absence of conventional risk factors among young adults

Objective

Coronary artery disease is major cause of mortality and morbidity. Homocysteine has long been postulated as an underlying factor for atherosclerosis leading to coronary artery disease, yet its role in young patients is uncertain. This study was aimed to analyze the correlation between plasma homocysteine and coronary artery disease among young adults in the absence of conventional risk factors.

Methods

It was a case-control study carried out at Rehman Medical Institute, Peshawar, Pakistan from October 1, 2016, to September 30, 2017. Universal sampling technique was adopted and 158 participants were included. A total of 30 participants were in the control group and 128 were in the patient group, who had moderate to severe stenosis in either single or multiple major coronary arteries on coronary angiography and aged <40 years.

Results

Cases and controls had similar characteristics but differed significantly in serum homocysteine concentration. In the control group, the mean plasma homocysteine concentration of 6.3 (±2.05) μmol/L and in the patient group a mean plasma homocysteine concentration of 44.5 (±14.01) μmol/L was observed. All the patients with moderate to severe stenosis in single or major coronary arteries had raised plasma homocysteine concentrations. Among 128 patients, 15 (11.7%) had moderate increase, 109 (85.2%) had intermediate increase, and four (3.1%) had severe increase in plasma homocysteine levels. Single vessel coronary artery disease was observed in 118 (92.2%) patients, whereas 10 (7.8%) had more than one major coronary artery involvement.

Conclusion

Hyper-homocysteinemia has positive correlation with coronary artery disease among young adults in the absence of conventional risk factors.

Stachydrine protects eNOS uncoupling and ameliorates endothelial dysfunction induced by homocysteine

BACKGROUND

Hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular diseases (CVDs). Stachydrine (STA) is an active component in Chinese motherwort Leonurus heterophyllus sweet, which has been widely used for gynecological and cardiovascular disorders. This study is aimed to examine the effects of STA on homocysteine (Hcy)-induced endothelial dysfunction.

METHODS

The effects of STA on vascular relaxation in rat thoracic aortas (TA), mesenteric arteries (MA) and renal arteries (RA) were measured by using Multi Myograph System. The levels of nitric oxide (NO), tetrahydrobiopterin (BH4) and guanosine 3', 5' cyclic monophosphate (cGMP) were determined. Endothelial nitric oxide synthase (eNOS) dimers and monomers were assayed by using Western blotting. GTP cyclohydrolase 1 (GTPCH1) and dihydrofolate reductase (DHFR) expressions were measured by using quantitative reverse transcriptase-PCR (qRT-PCR) and Western blotting.

RESULTS

STA effectively blocked Hcy-induced impairment of endothelium-dependent vasorelaxation in rat TA, MA and RA. STA-elicited arterial relaxations were reduced by NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) or the NO-sensitive guanylyl cyclase inhibitor 1H- [1, 2, 4] Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), but not by inducible iNOS inhibitor 1400 W nor the nonselective COX inhibitor indomethacin. Hcy caused eNOS uncoupling and decreases in NO, cGMP and BH4, which were attenuated by STA. Moreover, STA prevented decreases of GTPCH1 and DHFR levels in Hcy-treated BAECs.

CONCLUSION

We demonstrated that STA effectively reversed the Hcy-induced endothelial dysfunction and prevented eNOS uncoupling by increasing the expression of GTPCH1 and DHFR. These results revealed a novel mechanism by which STA exerts its beneficial vascular effects.

The influence of low-grade inflammation on platelets in patients with stable coronary artery disease

Inflammation is likely to be involved in all stages of atherosclerosis. Numerous inflammatory biomarkers are currently being studied, and even subtle increases in inflammatory biomarkers have been associated with increased risk of cardiovascular events in patients with coronary artery disease (CAD). Low-grade inflammation may influence both platelet production and platelet activation potentially leading to enhanced platelet aggregation. Thrombopoietin is considered the primary regulator of platelet production, but it likely acts in conjunction with numerous cytokines, of which many have altered levels in CAD. Previous studies have shown that high-sensitive C-reactive protein (CRP) independently predicts increased platelet aggregation in stable CAD patients. Increased levels of CRP, fibrinogen, interleukin-6, stromal cell-derived factor-1, CXC motif ligand 16, macrophage migration inhibitory factor, RANTES, calprotectin, and copeptin have been associated with increased risk of cardiovascular events in CAD patients. Additionally, some of these inflammatory markers have been associated with enhanced platelet activation and aggregation. However, CRP and other inflammatory markers provide only limited additional predictive value to classical risk factors such as smoking, blood pressure, and cholesterol levels. Existing data do not clarify whether inflammation simply accompanies CAD and increased production and aggregation of platelets, or whether a causal relationship exists. In this review, we provide a comprehensive overview of inflammatory markers in stable CAD with particular emphasis on platelet production, activation, and aggregation in CAD patients.

Claimed effects, outcome variables and methods of measurement for health claims proposed under European Community Regulation 1924/2006 in the framework of protection against oxidative damage and cardiovascular health

BACKGROUND AND AIMS

The high number of negative opinions from the European Food Safety Authority (EFSA) to the requests for authorization of health claims is largely due to the design of human intervention studies, including the inappropriate choice of outcome variables (OVs) and of their methods of measurement (MMs). The present manuscript reports the results of an investigation aimed to collect, collate and critically analyse the information in relation to claimed effects, OVs and MMs, in the context of protection against oxidative damage and cardiovascular health compliant with Regulation 1924/2006.

METHODS AND RESULTS

Claimed effects, OVs and the related MMs were collected from EFSA Guidance documents and applications for authorization of health claims under Articles 13.5 and 14. The OVs and their MMs were evaluated only if the claimed effect was sufficiently defined and was considered beneficial by EFSA. The collection, collation and critical analysis of the relevant scientific literature consisted in the definition of the keywords, the PubMed search strategies and the creation of databases of references. The critical analysis of the OVs and their MMs was performed on the basis of the literature review and was aimed at defining the appropriateness of OVs and MMs in the context of the specific claimed effects.

CONCLUSIONS

The information provided in this document could serve to EFSA for the development of further guidance on the scientific requirements for health claims, as well as to the stakeholders for the proper design of human intervention studies aimed to substantiate such health claims.

Inhibition of glutamate receptors reduces the homocysteine-induced whole blood platelet aggregation but does not affect superoxide anion generation or platelet membrane fluidization

Homocysteine (Hcy) is an excitotoxic amino acid. It is potentially possible to prevent Hcy-induced toxicity, including haemostatic impairments, by antagonizing glutaminergic receptors. Using impedance aggregometry with arachidonate and collagen as platelet agonists, we tested whether the blockade of platelet NMDA (N-methyl-D-aspartate), AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and kainate receptors with their inhibitors: MK-801 (dizocilpine hydrogen maleate, [5R,10S]-[+]-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine), CNQX (7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile) and UBP-302 (2-{[3-[(2S)-2-amino-2-carboxyethyl]-2,6-dioxo-3,6-dihydropyrimidin 1(2H)-yl]methyl}benzoic acid) may hamper Hcy-dependent platelet aggregation. All the tested compounds significantly inhibited Hcy-augmented aggregation of blood platelets stimulated either with arachidonate or collagen. Hcy stimulated the generation of superoxide anion in whole blood samples in a concentration-dependent manner; however, this process appeared as independent on ionotropic glutamate receptors, as well as on NADPH oxidase and protein kinase C, and was not apparently associated with the extent of either arachidonate- or collagen-dependent platelet aggregation. Moreover, Hcy acted as a significant fluidizer of surface (more hydrophilic) and inner (more hydrophobic) regions of platelet membrane lipid bilayer, when used at the concentration range from 10 to 50 µmol/l. However, this effect was independent on the Hcy action through glutamate ionotropic receptors, since there was no effects of MK-801, CNQX or UBP-302 on Hcy-mediated membrane fluidization. In conclusion, Hcy-induced changes in whole blood platelet aggregation are mediated through the ionotopic excitotoxic receptors, although the detailed mechanisms underlying such interactions remain to be elucidated.

A brief review on the mechanisms of aspirin resistance

Aspirin is the most widely prescribed drug for the primary and secondary prevention of cardiovascular and cerebrovascular diseases. However, a large number of patients continue to experience thromboembolic events despite aspirin therapy, a phenomenon referred to as aspirin resistance or treatment failure. Aspirin resistance is often observed along with a high incidence of unstable plaque, cardiovascular events and cerebrovascular accident. Studies have shown that aspirin reduces the production of TXA2, but not totally inhibits the activation of platelets. In this review, we analyze current and past research on aspirin resistance, presenting important summaries of results regarding the potential contributive roles of single nucleotide polymorphisms, inflammation, metabolic syndrome and miRNAs. The aim of this article is to provide a brief review on aspirin resistance and platelet function, which will provide important insights into the research of aspirin resistance.

Homocysteine Levels Influence Platelet Reactivity in Coronary Artery Disease Patients Treated With Acetylsalicylic Acid

BACKGROUND

Suboptimal platelet inhibition with antiplatelet treatments is associated with a severe prognosis in patients with coronary artery disease (CAD), and the identification of its determinants is still challenging. Homocysteine elevation has emerged as a prothrombotic factor, influencing coagulative status and endothelial function and potentially modulating platelet aggregation. We therefore aimed to evaluate the effects of homocysteine (Hcy) levels on platelet reactivity in patients receiving acetylsalicylic acid (ASA) with or without ADP antagonists.

METHODS

Patients undergoing coronary angiography and receiving ASA (100-160 mg daily) for >7 days, with or without ADP antagonists, were included. Aggregation tests were performed by multiple electrode aggregometry. Suboptimal platelet inhibition was defined as on-treatment aggregation above the lower limit of normality.

RESULTS

Our population is represented by 508 ASA-treated patients, 406 (80.1%) of whom on dual antiplatelet therapy (ASA and ADP antagonists). Hcy levels above the median (15.1 nmol/mL) were associated with male gender (P = 0.04), hypertension (P = 0.004), hypercholesterolemia (P = 0.03), aging, renal failure (P < 0.001, respectively), previous coronary bypass grafting (P = 0.04), therapy with calcium antagonists (P = 0.04) and diuretics (P = 0.001), and multivessel CAD (P = 0.03). Higher Hcy is directly related with serum creatinine and uric acid (P < 0.001). Suboptimal platelet inhibition was found in 16 patients (3.2%) for ASA and for ADP antagonists in 80 patients (19.7%). Hcy levels significantly affected suboptimal response to ASA, but not to ADP-mediated aggregation. In fact, a linear relationship was found between homocysteine and platelet reactivity after stimulation with arachidonic acid (r = 0.14, P = 0.004) and collagen (r = 0.12, P = 0.02), but not with ADP (r = 0.02, P = 0.77). Moreover, after correction for baseline differences, Hcy above the median was confirmed as an independent predictor of impaired ASA response [adjusted odds ratio (95% confidence interval) = 3.7 (1.08-12.4), P = 0.04].

CONCLUSIONS

Among patients with CAD, elevated homocysteine is an independent predictor of suboptimal response to ASA, but not to ADP antagonists.

Hyperhomocysteinemia is an independent predictor of long-term clinical outcomes in Chinese octogenarians with acute coronary syndrome

Objective

To evaluate the prognostic value of homocysteine (Hcy) in Chinese acute coronary syndrome (ACS) octogenarians.

Methods

The study cohort comprised 660 consecutive ACS octogenarians who underwent coronary angiography. We classified the patients into three groups according to Hcy tertiles. Kaplan–Meier method was performed for survival and major adverse cardiac events (MACE) rates. Multivariate Cox regression was performed to identify mortality predictors. Receiver operating characteristic curve analysis was performed to predict the cutoff value of Hcy for all-cause mortality.

Results

The follow-up period was 28 (inter-quartile range: 16–38) months. Diastolic blood pressure, ratios of male, renal failure and old myocardial infarction in high plasma level Hcy (H-Hcy) group were higher than those in low (L-Hcy) and middle (M-Hcy) plasma level of Hcy groups (P<0.05). The Hcy level was positively correlated with uric acid level (r=0.211, P=0.001) and Cystatin C (Cys C) level (r=0.212, P=0.001) and negatively correlated with estimated glomerular filtration rate (r=−0.148, P=0.018). For the long-term outcomes, the cumulative survival rate of H-Hcy group was significantly lower than that of L-Hcy and M-Hcy groups (P=0.006). All-cause mortality and MACE of H-Hcy group were higher than those of L-Hcy and M-Hcy group (P=0.0001, P=0.0008). Hcy is an independent predictor for long-term all-cause mortality (odds ratio =2.26, 95% CI=1.23–4.16, P=0.023) and MACE (odds ratio =1.91, 95% CI=1.03–3.51, P=0.039). Receiver operating characteristic curve analysis indicated the predictive cutoff value of Hcy for all-cause mortality was 17.67 μmol/L (0.667, 0.681).

Conclusion

In ACS octogenarians, hyperhomocysteinemia is an important predictor for long-term all-cause mortality and MACE.

Platelet aggregation values in patients with cardiovascular risk factors are reduced by verbascoside treatment. A randomized study

Verbascoside, a phenolic compound, showed several favorable biological activities, including an antiplatelet activity. No in vivo studies tested its efficacy and safety in subjects with cardiovascular (CV) factors. The aim of this randomized, single-center, double-blind, phase II study was to assess the efficacy and tolerability of verbascoside intake for the modulation of platelet aggregation (PA) values in subjects with cardiovascular (CV) risk factors. One-hundred subjects with at least one CV risk factor (age >65 years, diabetes mellitus, hypertension, current cigarettes use, hyperlidemia, waist circumference >102 cm in male or >88 cm in female) were enrolled and randomly assigned to receive placebo or verbascoside 50mg or verbascoside 100mg. PA was measured at baseline and after 2 weeks of study drug assumption, with light transmittance aggregometry (arachidonic acid, AA, 1 μM and adenosine diphosphate, ADP, 5 μM). Two weeks of treatment with placebo or verbascoside 50mg did not modify PA values (both after AA and ADP stimuli). On the contrary, after 2 weeks of verbascoside 100mg, PA values decreased significantly (from 51 ± 13% to 39 ± 15%, p<0.01 after AA; from 60 ± 12% to 49 ± 15%, p = 0.01 after ADP). No serious adverse events were reported during the study, and no subjects discontinued the study because of adverse events. We conclude that long-term intake of verbascoside 100mg significantly reduces PA values in subjects with CV risk factors.

Polymorphisms in catechol-O-methyltransferase modify treatment effects of aspirin on risk of cardiovascular disease

OBJECTIVE

Catechol-O-methyltransferase (COMT), a key enzyme in catecholamine metabolism, is implicated in cardiovascular, sympathetic, and endocrine pathways. This study aimed to confirm preliminary association of COMT genetic variation with incident cardiovascular disease (CVD). It further aimed to evaluate whether aspirin, a commonly used CVD prevention agent, modified the potential association of COMT with incident CVD.

APPROACH AND RESULTS

We examined COMT polymorphism rs4680 (MAF [minor allele frequency], 0.47), encoding a nonsynonymous methionine-to-valine substitution, in the Women's Genome Health Study (WGHS), a large population-based cohort of women with randomized allocation to aspirin or vitamin E when compared with placebo and 10-year follow-up. Rs4680 effects were confirmed with COMT polymorphism rs4818 and also examined in Coronary ARtery DIsease Genome-wide Replication and Meta-analysis/The Coronary Artery Disease Genetics Consortium, consortia for genome-wide association studies of coronary artery disease. Among WGHS women allocated to placebo (135 events/n=5811), the rs4680 valine allele was protective against incident CVD relative to the methionine (hazard ratio [HR; 95% confidence interval {CI}], 0.66 [0.51-0.84]; P=0.0007); an association also observed in Coronary ARtery DIsease Genome-wide Replication and Meta-analysis and The Coronary Artery Disease Genetics Consortium (combined P=2.4×10(-5)). In the WGHS, the rs4680 association was abolished by randomized allocation to aspirin, such that valine/valine women experienced higher CVD rates with aspirin allocation when compared with placebo (HR [95% CI], 1.85 [1.05-3.25]; P=0.033), whereas methionine/methionine women experienced lower rates (HR [95% CI], 0.60 [0.39-0.93]; P=0.023). Allocation to vitamin E also conferred higher but nonsignificant CVD rates on valine/valine (HR [95% CI], 1.50 [0.83-2.70]; P=0.180) when compared with significantly lower rates on methionine/methionine (HR [95% CI], 0.53 [0.34-0.84]; P=0.006) women. Rs4818 results were similar.

CONCLUSIONS

Common COMT polymorphisms were associated with incident CVD, and this association was modified by randomized allocation to aspirin or vitamin E. Replication of these findings is required.

Homocysteine is associated with plasma high-sensitivity cardiac troponin T levels in a community-dwelling population

Objectives

Homocysteine (HCY) is associated with an increased risk for cardiovascular disease, possibly leading to myocardial damage. Cardiac troponin T (TnT), a marker of cardiomyocyte injury, can be detected by high-sensitivity TnT (hsTnT) assay. The current study investigated the relationship between plasma HCY and hsTnT levels in a community-based population.

Methods

We related plasma levels of hsTnT to HCY levels in 1,497 participants (mean age, 62.4 years; 629 men, 868 women) from a community-based population in Beijing, People’s Republic of China.

Results

In multiple logistic regression models, serum HCY was associated with a higher likelihood of detectable hsTnT (odds ratio 1.5; 95% confidence interval 1.07–2.10; P=0.018). A subsequent subgroup analysis found that in subjects aged 65 years and older, the association between hsTnT levels and HCY levels was strengthened. The association between hsTnT and HCY was not present in the younger subgroup (<65 years old).

Conclusion

Levels of serum HCY are associated with hsTnT levels in the elderly, indicating a relationship between HCY and subclinical myocardial damage.

The Janus face of PAMAM dendrimers used to potentially cure nonenzymatic modifications of biomacromolecules in metabolic disorders-a critical review of the pros and cons

Diabetes mellitus, which is characterised by high blood glucose levels and the burden of various macrovascular and microvascular complications, is a cause of much human suffering across the globe. While the use of exogenous insulin and other medications can control and sometimes prevent various diabetes-associated sequelae, numerous diabetic complications are still commonly encountered in diabetic patients. Therefore, there is a strong need for safe and effective antihyperglycaemic agents that provide an alternative or compounding option for the treatment of diabetes. In recent years, amino-terminated poly(amido)amine (PAMAM) dendrimers (G2, G3 and G4) have attracted attention due to their protective value as anti-glycation and anti-carbonylation agents that can be used to limit the nonenzymatic modifications of biomacromolecules. The focus of this review is to present a detailed survey of our own data, as well as of the available literature regarding the toxicity, pharmacological properties and overall usefulness of PAMAM dendrimers. This presentation pays particular and primary attention to their therapeutic use in poorly controlled diabetes and its complications, but also in other conditions, such as Alzheimer’s disease, in which such nonenzymatic modifications may underlie the pathophysiological mechanisms. The impact of dendrimer administration on the overall survival of diabetic animals and on glycosylation, glycoxidation, the brain-blood barrier and cellular bioenergetics are demonstrated. Finally, we critically discuss the potential advantages and disadvantages accompanying the use of PAMAM dendrimers in the treatment of metabolic impairments that occur under conditions of chronic hyperglycaemia.