Elevated total homocysteine is associated with increased platelet activation at the site of microvascular injury: effects of folic acid administration

Effect of plateletcrit and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on folic acid efficacy in stroke prevention

Previous studies have shown that low platelet count combined with high plasma total homocysteine (tHcy) increased stroke risk and can be lowered by 73% with folic acid. However, the combined role of other platelet activation parameters and the methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on stroke risk and folic acid treatment benefit remain to be examined. This study aimed to investigate if platelet activation parameters and MTHFR genotypes jointly impact folic acid treatment efficacy in first stroke prevention. Data were derived from the China Stroke Primary Prevention Trial. This study includes a total of 11,185 adult hypertensive patients with relevant platelet activation parameters and MTHFR genotype data. When simultaneously considering both platelet activation parameters (plateletcrit, platelet count, mean platelet volume, platelet distribution width) and MTHFR genotypes, patients with both low plateletcrit (Q1) and the TT genotype had the highest stroke incidence rate (5.6%) in the enalapril group. This subgroup significantly benefited from folic acid treatment, with a 66% reduction in first stroke (HR: 0.34; 95% CI: 0.14-0.82; p = 0.016). Consistently, the subgroup with low plateletcrit (Q1) and the CC/CT genotype also benefited from folic acid treatment (HR: 0.40; 95% CI: 0.23-0.70; p = 0.001). In Chinese hypertensive adults, low plateletcrit can identify those who may greatly benefit from folic acid treatment, in particular, those with the TT genotype, a subpopulation known to have the highest stroke risk.

Platelet Metabolic Profiling Reveals Glycolytic and 1-Carbon Metabolites Are Essential for GP VI-Stimulated Human Platelets-Brief Report

BACKGROUND

Evolving evidence suggests that besides signaling pathways, platelet activation involves a complex interplay between metabolic pathways to support thrombus growth. Selective targeting of metabolic checkpoints may inhibit platelet activation and provide a novel antiplatelet strategy. We, therefore, examined global metabolic changes that occur during the transition of human platelets from resting to an activated state to identify metabolites and associated pathways that contribute to platelet activation.

METHODS

We performed metabolic profiling of resting and convulxin-stimulated human platelet samples. The differential levels, pathway analysis, and PCA (principal component analysis) were performed using Metaboanalyst. Metascape was used for metabolite network construction.

RESULTS

Of the 401 metabolites identified, 202 metabolites were significantly upregulated, and 2 metabolites were downregulated in activated platelets. Of all the metabolites, lipids scored highly and constituted ≈50% of the identification. During activation, aerobic glycolysis supports energy demand and provides glycolytic intermediates required by metabolic pathways. Consistent with this, an important category of metabolites was carbohydrates, particularly the glycolysis intermediates that were significantly upregulated compared with resting platelets. We found that lysophospholipids such as 1-palmitoyl-GPA (glycero-3-phosphatidic acid), 1-stearoyl-GPS (glycero-3-phosphoserine), 1-palmitoyl-GPI (glycerophosphoinositol), 1-stearoyl-GPI, and 1-oleoyl-GPI were upregulated in activated platelets. We speculated that platelet activation could be linked to 1-carbon metabolism, a set of biochemical pathways that involve the transfer and use of 1-carbon units from amino acids, for cellular processes, including nucleotide and lysophospholipid synthesis. In alignment, based on pathway enrichment and network-based prioritization, the metabolites from amino acid metabolism, including serine, glutamate, and branched-chain amino acid pathway were upregulated in activated platelets, which might be supplemented by the high levels of glycolytic intermediates.

CONCLUSIONS

Metabolic analysis of resting and activated platelets revealed that glycolysis and 1-carbon metabolism are necessary to support platelet activation.

Combined use of amlodipine and folic acid are significantly more efficacious than amlodipine alone in lowering plasma homocysteine and blood pressure among hypertensive patients with hyperhomocysteinemia and intolerance to ACEI: A multicenter, randomized, double-blind, parallel-controlled clinical trial

Hyperhomocysteinemia with hypertension can synergistically increase the risk of stroke. The China stroke primary prevention trial showed that combining 0.8 mg folic acid (FA) with angiotensin-converting enzyme inhibitor (ACEI) can effectively lower plasma total homocysteine (tHcy) and blood pressure (BP); and reduce first stroke risk by additional 21% compared to ACEI alone. However, intolerance to ACEI is common in Asians and amlodipine can be alternative. This is a multicenter, randomized, double-blind, parallel-controlled clinical trial (RCT) which evaluated whether amlodipine combined with FA is more efficacious than amlodipine alone in lowering tHcy and BP among Chinese hypertensive with hyperhomocysteinemia and intolerance to ACEI. 351 Eligible patients were randomly assigned by 1:1:1 ratio to receive amlodipine-FA tablet daily (amlodipine 5 mg/FA 0.4 mg, A group); amlodipine 5 mg/FA 0.8 mg tablet daily (B group); amlodipine 5 mg daily (C group, control group). Follow-up was conducted at 2, 4, 6, and 8 weeks. The primary outcome was efficacy of lowering both tHcy and BP at the end of 8-week treatment. Compared with C group, A group had a significantly higher rate of lowering both tHcy and BP (23.3% vs. 6.0%; Odds Ratio [OR], 8.68; 95% CI, 3.04-24.78, P < .001); B group also had a higher rate of lowering both tHcy and BP (20.3% vs. 6.0%; OR: 5.90; 95% CI, 2.11-16.47, P < .001). This RCT showed amlodipine combined with FA compared with amlodipine alone, each had significantly higher efficacy of lowering both tHcy and BP. No difference was found in BP-lowering and occurrence of adverse events between the three groups.

Longitudinal Analysis of 1α,25-dihidroxyvitamin D3 and Homocysteine Changes in Colorectal Cancer

Simple Summary

Vitamin D₃ and homocysteine level abnormalities are both strongly related to colorectal cancer (CRC) etiology. The aim of this retrospective study was to investigate the longitudinal change in these two parameters and the relationships between the two, in addition with other clinicopathological and laboratory parameters. A swoosh-shaped trend was observed for the change in serum homocysteine levels of all of the CRC patients. The circulating vitamin D₃ level was constant or increased in those patients without metastasis. After an initial increase, the disease-worsening effect of metastases cancelled out all of the positive effects of vitamin D₃ in metastatic patients, even despite its continuous supplementation. Right-sided tumors, male sex, and the pathological values of serum lipids, albumin, total protein, and inflammatory markers were associated with lower vitamin D₃ and higher homocysteine level. Based on our results, we recommend a modified vitamin D₃ supplementation regimen for metastatic CRC, which includes laboratory measurement-based titration.

Abstract

Background: 1α,25-dihydroxycholecalciferol (1,25(OH)₂D₃) and homocysteine are known to play a role in the pathophysiology of colorectal cancer (CRC). In health, the two changes are inversely proportional to each other, but little is known about their combined effect in CRC. Methods: The serum 1,25(OH)₂D₃ and the homocysteine levels of eighty-six CRC patients were measured, who were enrolled into four cohorts based on the presence of metastases (Adj vs. Met) and vitamin D₃ supplementation (ND vs. D). Results: 1,25(OH)₂D₃ was constant (Adj-ND), increased significantly (Adj-D, p = 0.0261), decreased (Met-ND), or returned close to the baseline after an initial increase (Met-D). The longitudinal increase in 1,25(OH)₂D₃ (HR: 0.9130, p = 0.0111) positively affected the overall survival in non-metastatic CRC, however, this effect was cancelled out in those with metastasis (p = 0.0107). The increase in homocysteine negatively affected both the overall (HR: 1.0940, p = 0.0067) and the progression-free survival (HR: 1.0845, p = 0.0073). Lower 1,25(OH)₂D₃ and/or higher homocysteine level was characteristic for patients with higher serum lipids, albumin, total protein, white blood cell and platelet count, male sex, and right-sided tumors. No statistically justifiable connection was found between the target variables. Conclusions: A measurement-based titration of vitamin D₃ supplementation and better management of comorbidities are recommended for CRC.

A randomized placebo-controlled trial of using B vitamins to prevent cognitive decline in older mild cognitive impairment patients

BACKGROUND & AIMS

Mild cognitive impairment (MCI) patients are at risk of cognitive decline, while elevated serum homocysteine is also associated with cognitive impairment. Thus, older people with MCI and hyperhomocysteinemia may be under greater risk of cognitive decline. We therefore performed a randomized trial of homocysteine-lowering by B vitamins supplementation to prevent cognitive decline in older MCI patients with elevated serum homocysteine.

METHODS

279 MCI outpatients aged ≥65 years with serum homocysteine ≥10.0 μmol/L were randomly assigned to take either methylcobalamin 500 μg and folic acid 400 μg once daily, or two placebo tablets for 24 months. All subjects were followed up at 12 monthly intervals. The primary outcome was cognitive decline as defined by an increase in clinical dementia rating scale (CDR) sum of boxes (CDR_SOB). The secondary outcomes were global CDR, memory Z score, executive function Z score and Hamilton depression rating scale (HDRS) score.

RESULTS

The clinical characteristics between two groups were well matched, except that the supplement group had better executive function. The supplement effectively lowered serum homocysteine (mean 13.9 ± sd 3.5 μmol at baseline to 9.3 ± 2.4 μmol/L at month 24). At month 24, there was no significant group difference in CDR_SOB or any secondary outcomes (mean changes in CDR_SOB 0.36 versus 0.22 in supplement and placebo groups respectively). At month 12, the supplement group significantly improved in executive function and had lower HDRS score (P = 0.004 and 0.012 respectively). Group difference was significant for HDRS, but borderline significant for executive function. (P = 0.01; 0.06 respectively) These effects were not significant at month 24. Subgroup analysis showed that aspirin use had significant interaction with B supplements in CDR_SOB at month 24 (Beta 0.189, P = 0.005).

CONCLUSIONS

Vitamin B₁₂ and folic acid supplementation did not reduce cognitive decline in older people with MCI and elevated serum homocysteine, though the cognitive decline over two years in placebo group was small. The supplement led to a significant reduction in depressive symptoms at month 12, though this effect was not sustained. Aspirin use had a negative interaction effect on cognitive functioning with B supplements.

CLINICAL TRIAL REGISTRATION

Centre for Clinical Research and Biostatistics (CCRB) Clinical Trials Registry: CUHK_CCT00373.

Association of plasma homocysteine level with vaso-occlusive crisis in sickle cell anemia patients of Odisha, India

Vascular complications of sickle cell anemia (SCA) are influenced by many factors. Elevated plasma homocysteine (Hcy) is supposed to be an independent risk factor and is either genetic or nutritional origin. The present study evaluated the plasma Hcy level, MTHFR C677T gene polymorphism, effect of folic acid (FA) supplementation' and hemato-biochemical parameters in SCA and their effect on the vaso-occlusive crisis (VOC) in SCA patients of an Asian-Indian haplotype population. One hundred twenty cases of SCA (HbSS) and 50 controls with normal hemoglobin(HbAA) were studied. It was found that the plasma Hcy level is significantly higher (p < 0.0001) in patients with SCA (22.41 ± 7.8 μmol/L) compared to controls (13.2 ± 4.4 μmol/L). Moreover, patients without FA supplementation had a significantly (p < 0.001) higher Hcy level (27 ± 7 μmol/L) compared to those with supplementation (17.75 ± 5.7 μmol/L). Turkey-Kramer multiple comparison tests show that there is a significant difference (p < 0.05) in HbF percent, hemoglobin (Hb), platelet count, serum bilirubin (direct:Bil-D and total:Bil-T), aspartate transaminase (AST), lactate dehydrogenase (LDH), and plasma Hcy levels between mild and severe VOC. Between moderate VOC and severe VOC, there was a significant difference (p < 0.05) in HbF%, Bil-D, AST, Hcy. Pearson correlation revealed that plasma Hcy had a significantly (p < 0.05) positive correlation with AST, serum bilirubin (indirect and total), LDH, jaundice, stroke, VOC per year, and hospitalization per year whereas it was inversely correlated with HbF percentage, Hb level, and FA treatment. In the study population, increased plasma Hcy level, hemolysis, and platelet activation were found to influence VOC in SCA.

High detection rates of antithrombin deficiency and antiphospholipid syndrome in outpatients aged over 50 years using the standardized protocol for thrombophilia screening

INTRODUCTION

Thrombophilia screening has limited detection efficiency. We assessed the detection rate when a standardized approach to thrombophilia-screened outpatients was used.

METHODS

We analyzed 1185 patients (36.5% males, median age: 43 years [IQR 33-54]) referred to a single center from January 2014 to October 2017 with 11 different clinical indications for thrombophilia screening, which was performed in the adherence to published guidelines. Factor V Leiden, prothrombin G20210A mutation, antithrombin (AT), protein C, protein S deficiencies and antiphospholipid syndrome (APS) were determined.

RESULTS

The overall positivity rate was 37.1% (95% CI 34.3%-39.7%). The highest positivity rate was found in women following VTE during pregnancy/childbirth (64.1%) and provoked VTE patients with positive family history (52.9%). In patients aged >50 years (32.5%), APS was found at a similar rate as in younger subjects (11.4% vs 10.1%), while AT deficiency was detected more frequently in the older group (5.7% vs 2.4%, p = 0.003).

CONCLUSIONS

Standard indications for thrombophilia screening lead to detection rates of 37% or more. Frequent detection of APS and AT deficiency among older patients, which often implies a need for long-term anticoagulation and could impact clinical practice patterns, suggests a benefit of thrombophilia screening in this population in selected clinical circumstances.

Coagulology, biochemical profile and muscle pathology in calves diagnosed with nutritional muscular dystrophy

The aim of this study was to explain the correlations between selenium deficiency, hemostatic and biochemical disorders, and the progression of pathological changes in calves diagnosed with nutritional muscular dystrophy (NMD). The study was performed on 20 calves with supplementation of 8 ml selenium and vitamin E preparation and 20 calves with symptoms of NMD. Blood was sampled from calves aged 5, 12 and 19 days. On day 19, samples of the biceps femoris muscle were collected from 6 animals in each group for histopathological analysis. The following blood parameters were determined: PLT, PT, TT, APTT, fibrinogen and D-dimer concentrations, antithrombin III activity, glucose, selenium and vitamin E concentrations, activity of CK, LDH and GSH-Px. Muscle sections were stained with H&E and HBFP. Platelet counts were significantly lower in calves with symptoms of NMD. No significant differences in coagulation parameters were observed between the groups. Sick calves were diagnosed with hyperglycemia and elevation of CK and LDH activity. Selenium and vitamin E concentrations in the blood serum were significantly lower in the experimental group together with significant drop in GSH-Px activity. Changes characteristic of Zenker's necrosis were observed in a muscle of the sick animals. To our best knowledge this is the first study in which the attempt was made to explain the relationship between selenium deficiency and changes in the coagulation system in ruminants.

Folic Acid Supplementation and the Risk of Cardiovascular Diseases: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Results from observational and genetic epidemiological studies suggest that lower serum homocysteine levels are associated with lower incidence of cardiovascular disease (CVD). Numerous randomized controlled trials have investigated the efficacy of lowering homocysteine with folic acid supplementation for CVD risk, but conflicting results have been reported.

METHODS AND RESULTS

Three bibliographic databases (Medline, Embase, and the Cochrane Database of Systematic Reviews) were searched from database inception until December 1, 2015. Of the 1933 references reviewed for eligibility, 30 randomized controlled trials involving 82 334 participants were included in the final analysis. The pooled relative risks of folic acid supplementation compared with controls were 0.90 (95% CI 0.84-0.96; P=0.002) for stroke, 1.04 (95% CI 0.99-1.09; P=0.16) for coronary heart disease, and 0.96 (95% CI 0.92-0.99; P=0.02) for overall CVD. The intervention effects for both stroke and combined CVD were more pronounced among participants with lower plasma folate levels at baseline (both P<0.02 for interaction). In stratified analyses, a greater beneficial effect for overall CVD was seen in trials among participants without preexisting CVD (P=0.006 for interaction) or in trials with larger reduction in homocysteine levels (P=0.009 for interaction).

CONCLUSIONS

Our meta-analysis indicated a 10% lower risk of stroke and a 4% lower risk of overall CVD with folic acid supplementation. A greater benefit for CVD was observed among participants with lower plasma folate levels and without preexisting CVD and in studies with larger decreases in homocysteine levels. Folic acid supplementation had no significant effect on risk of coronary heart disease.

Comparative antiadhesive properties of crude extract and phenolic fraction isolated from aerial parts of Tribulus pterocarpus during severe hyperhomocysteinemia

The phenolic fraction and the crude extract from Tribulus pterocarpus have different biological activity, including antiplatelet-antiadhesive properties. Since it is demonstrated that hyperhomocysteinemia may act as stimulator of blood platelet activation (platelet adhesion, aggregation, and secretion), but various antiplatelet compounds are able to reduce hyperactivation of blood platelets induced by hyperhomocysteinemia. The aim of our present experiments was to investigate in vitro one of the step in platelet activation process - platelet adhesion to collagen induced by the model of severe hyperhomocyateinemia in the presence of the phenolic fraction and the crude extract from T. pterocarpus. Severe hyperhomocysteinemia was induced by reduced form of Hcy in the concentrations 0.1mM and 1mM, or using HTL in the concentrations 0.1, 0.5 and 1 μM. Adhesion of blood platelets to collagen was determined according to Tuszynski and Murphy. We observed that the phenolic fraction and the crude extract from T. pterocarpus have the inhibitory effect on platelet adhesion during severe hyperhomocysteinemia. The action of tested phenolic and crude extract was concentration-dependent, but the phenolic fraction was stronger antiadhesive action than the crude extract. We suggest that T. pterocarpus may be good source of antiplatelet compounds during hyperhomocysteinemia.

The polyphenol-rich extracts from black chokeberry and grape seeds impair changes in the platelet adhesion and aggregation induced by a model of hyperhomocysteinemia

OBJECTIVE

The mechanism action of the polyphenol-rich extracts from berries of Aronia melanocarpa (black chokeberry) and from grape seeds in the defence against homocysteine (Hcy) and its derivatives action in blood platelets is still unknown. In this study, the influence of the aronia extract and grape seeds extract (GSE) on the platelet adhesion to collagen and fibrinogen and the platelet aggregation during a model of hyperhomocysteinemia was investigated. The aim of our study in vitro was also to investigate superoxide anion radicals (O₂⁻•) production after incubation of platelets with Hcy, HTL and the aronia extract and GSE during a model of hyperhomocysteinemia (induced by reduced form of homocysteine at final dose of 100 μM) and the most reactive form of Hcy--its cyclic thioester, homocysteine thiolactone (HTL, 1 μM). Moreover, the additional aim of our study was also to establish and compare the influence of the aronia extract, GSE and resveratrol (3,4',5-trihydroxystilben), a phenolic compound, which has been supposed to be beneficial for the prevention of cardiovascular events, on selected steps of platelet activation.

METHODS

The effects of tested extracts on adhesion of blood platelets to collagen and fibrinogen were determined according to Tuszynski and Murphy. The platelet aggregation was determined by turbidimetry method using a Chrono-log Lumi-aggregometer.

RESULTS

We have observed that HTL, like its precursor-Hcy stimulated the generation of O₂⁻• (measured by the superoxide dismutase-inhibitable reduction of cytochrome c) in platelets and caused an augmentation of the platelet adhesion and aggregation induced by the strong physiological agonist-thrombin. Our present results in vitro also demonstrated that the aronia extract and grape seeds extract reduced the toxicity action of Hcy and HTL on blood platelet adhesion to collagen and fibrinogen, the platelet aggregation and superoxide anion radicals production in platelets, suggesting its potential protective effects on hemostasis during hyperhomocysteinemia.

CONCLUSION

In the comparative studies, the aronia extract was found to be more effective antiplatelet factors, than GSE or resveratrol during a model of hyperhomocysteinemia. It gives hopes for development of diet supplements, which may be important during hyperhomocysteinemia.

Response of blood platelets to resveratrol during a model of hyperhomocysteinemia

Resveratrol (3,4',5-trihydroxystilben), a phenolic antioxidant synthesized in grapes and other plants, and also present in wine, has been suggested to help prevent cardiovascular events. In this study the influence of resveratrol on platelet aggregation during a model of hyperhomocysteinemia was investigated. We induced hyperhomocysteinemia using a reduced form of Hcys (final dose, 0.1 mM) and the most reactive form of Hcys, its cyclic thioester, homocysteine thiolactone (HTL, 1 µM). The aim of our study in vitro was also to investigate superoxide anion radical (O(2)(-)) generation after incubation of platelets with Hcys, HTL, and resveratrol. We have observed that HTL, like its precursor Hcys, stimulated the generation of (O(2)(-) in platelets and caused an augmentation of platelet aggregation induced by the strong physiological agonist thrombin. Our results in vitro also demonstrated that resveratrol reduced the toxic action of Hcys and HTL on blood platelet aggregation and superoxide anion radical production in platelets, suggesting its potential protective effects on hemostasis are negatively influenced by homocysteine and its derivatives.

Reconciling the evidence on serum homocysteine and ischaemic heart disease: a meta-analysis

Background

Results from genetic epidemiological studies suggest that raised serum homocysteine is a cause of ischaemic heart disease, but the results of randomised trials suggest otherwise. We aimed to update meta-analyses on each type of study using the latest published data and test a hypothesis based on antiplatelet therapy use in the trials to explain the discrepancy.

Methods and Findings

Meta-analyses of ischaemic heart disease using (i) 75 studies in which the prevalence of a mutation (CT) in the MTHFR gene (which increases homocysteine) was determined in cases (22,068) and controls (23,618), and (ii) 14 randomised trials (39,597 participants) of homocysteine lowering and ischaemic heart disease events. The summary estimates from the two analyses were compared. Meta-analysis of the MTHFR studies showed a statistically significantly increased risk of ischaemic heart disease in TT compared with CC homozygotes; odds ratio 1.16 (1.04 to 1.29) for a 1.9 µmol/L homocysteine difference (TT minus CC). Meta-analysis of randomised trials showed no significant reduction in IHD risk from folic acid; relative risk 1.00 (0.93 to 1.08), despite a reduction in homocysteine of 3.3 µmol/L. There was a statistically significant difference in risk reduction between the 5 trials with the lowest prevalence of antiplatelet therapy (60% on average, usually aspirin), RR 0.93 (0.84 to 1.05) and the 5 trials with the highest prevalence (91% on average), RR 1.09 (1.00 to 1.19), p = 0.037 for the difference.

Conclusion

Discordant results from MTHFR studies and randomised trials could be explained by aspirin reducing or negating the anti-platelet effect of lowering homocysteine. On this basis, folic acid would have a role in the primary prevention of ischaemic heart disease, when aspirin is not taken routinely, but not in secondary prevention, when it is routine.

Comparative studies on homocysteine and its metabolite-homocysteine thiolactone action in blood platelets in vitro

Homocysteine (Hcy), an intermediate formed during the catabolism of the essential dietary amino acid methionine, and its cyclic thioester, homocysteine thiolactone (TL) formed from Hcy in plasma, may be implicated in pathological haemostasis and atherosclerosis. The mechanism by which TL exerts the prothrombotic effect and influences blood platelets remains unclear. Activation of blood platelets plays an important role in prothrombotic events. The aim of our study was to establish and compare the influence of a reduced form of homocysteine (at final doses of 10-100 microM) and its cyclic thioester, homocysteine thiolactone (0.1-1 microM), on platelet activation induced by thrombin (platelet aggregation), on platelet protein modifications (determined by parameters such as level of protein carbonyl groups, 3-nitrotyrosine residues in proteins) and on superoxide anion radicals ( O2-*) generation using the model system in vitro. We have observed that TL, like its precursor, Hcy, stimulates the generation of O2* in platelets and causes an augmentation of platelet aggregation induced by thrombin. Our present results in vitro also demonstrate that Hcy (10-100 microM) and TL at lower doses than Hcy (0.1-1 microM) cause modification of platelet proteins: diminished formation of carbonyl groups and distinctly decreased tyrosine nitration in platelet proteins after thrombin stimulation, but increased platelet aggregation induced by thrombin. TL like Hcy (at concentrations corresponding to concentrations in blood during hyperhomocysteinemia) modifies platelet responses to an important physiological agonist--thrombin.

Hyperglycemia is associated with enhanced thrombin formation, platelet activation, and fibrin clot resistance to lysis in patients with acute coronary syndrome

OBJECTIVE

Acute hyperglycemia on admission for acute coronary syndrome worsens the prognosis in patients with and without known diabetes. Postulated mechanisms of this observation include prothrombotic effects. The aim of this study was to evaluate the effect of elevated glucose levels on blood clotting in acute coronary syndrome patients.

RESEARCH DESIGN AND METHODS

We studied 60 acute coronary syndrome patients within the first 12 h after pain onset, including 20 subjects with type 2 diabetes, 20 subjects with no diagnosed diabetes but with glucose levels >7.0 mmol/l, and 20 subjects with glucose levels <7.0 mmol/l. We determined generation of thrombin-antithrombin complexes (TATs) and soluble CD40 ligand (sCD40L), a platelet activation marker, at the site of microvascular injury, together with ex vivo plasma fibrin clot permeability and lysis time.

RESULTS

The acute coronary syndrome patients with no prior diabetes but elevated glucose levels had increased maximum rates of formation and total production of TATs (by 42.9%, P < 0.0001, and by 25%, P < 0.0001, respectively) as well as sCD40L release (by 16.2%, P = 0.0011, and by 16.3%, P < 0.0001, respectively) compared with those with normoglycemia, whereas diabetic patients had the highest values of TATs and sCD40L variables (P < 0.0001 for all comparisons). Patients with hyperglycemia, with no previously diagnosed diabetes, had longer clot lysis time (by approximately 18%, P < 0.0001) similar to that in diabetic subjects, but not lower clot permeability compared with that in normoglycemic subjects.

CONCLUSIONS

Hyperglycemia in acute coronary syndrome is associated with enhanced local thrombin generation and platelet activation, as well as unfavorably altered clot features in patients with and without a previous history of diabetes.

Strategies for antiplatelet targets and agents

Platelets play a key role in thrombosis and haemostasis, which can be either beneficial or deleterious depending on the circumstance. Antiplatelet therapy is the 'cornerstone' in the prevention and treatment of thrombotic diseases. Platelet activation is a complex process known as transmembrane signaling which then serves to activate the platelet via a cascade of biochemical interactions. Currently available strategies of antiplatelet therapy are generally based on the signaling pathway of platelet activation, which possess the characters that mono-agent, mono-target, and mainly irreversible inhibition. Therefore, both established and novel antiplatelet agents have their own pros and cons and such problems as resistance, drug-drug interaction, discontinuation and monitoring, etc. have been appeared. Due to the problems existing in current antiplatelet agents, future new strategies for antiplatelet targets, agent-developing and treatment might probably include three aspects: targeting the factors associated with platelet hyperactivity, developing novel antiplatelet agents with multiple targets, mild and reversible properties from natural products, and keeping healthy lifestyle and emphasizing prevention.

Efficacy of folic acid supplementation in stroke prevention: a meta-analysis

BACKGROUND

The efficacy of treatments that lower homocysteine concentrations in reducing the risk of cardiovascular disease remains controversial. Our aim was to do a meta-analysis of relevant randomised trials to assess the efficacy of folic acid supplementation in the prevention of stroke.

METHODS

We collected data from eight randomised trials of folic acid that had stroke reported as one of the endpoints. Relative risk (RR) was used as a measure of the effect of folic acid supplementation on the risk of stroke with a random effect model. The analysis was further stratified by factors that could affect the treatment effects.

FINDINGS

Folic acid supplementation significantly reduced the risk of stroke by 18% (RR 0.82, 95% CI 0.68-1.00; p=0.045). In the stratified analyses, a greater beneficial effect was seen in those trials with a treatment duration of more than 36 months (0.71, 0.57-0.87; p=0.001), a decrease in the concentration of homocysteine of more than 20% (0.77, 0.63-0.94; p=0.012), no fortification or partly fortified grain (0.75, 0.62-0.91; p=0.003), and no history of stroke (0.75, 0.62-0.90; p=0.002). In the corresponding comparison groups, the estimated RRs were attenuated and insignificant.

INTERPRETATION

Our findings indicate that folic acid supplementation can effectively reduce the risk of stroke in primary prevention.