Is sialic acid an independent risk factor for cardiovascular disease? A 17-year follow-up study in Busselton, Western Australia

N-acetylneuraminic acid modulates SQSTM1/p62 sialyation-mediated ubiquitination degradation contributing to vascular endothelium dysfunction in experimental atherosclerosis mice

Sialic acid (SIA) has been reported to be a risk factor for atherosclerosis (AS) due to its high plasma levels in such patients. However, the effect of increasing SIA in circulation on endothelial function during AS progression remains unclear. In the present study, ApoE-/- mice and endothelial cells line (HUVEC cells) were applied to investigate the effect of SIA on AS progression and its potential molecular mechanism. In vivo, mice were injected intraperitoneally with Neu5Ac (main form of SIA) to keep high-level SIA in circulation. ORO, H&E, and Masson staining were applied to detect the plaque progression. In vitro, HUVECs were treated with Neu5Ac at different times, CCK-8, RT-PCR, western blot, and immunoprecipitation methods were used to analyze its effects on endothelial function and the potential involved mechanism. Results from the present study showed that high plasma levels of Neu5Ac in ApoE-/- mice could aggravate the plaque areas as well as increase necrotic core areas and collagen fiber contents. Remarkably, Neu5Ac levels in circulation displayed a positive correlation with AS plaque areas. Furthermore, results from HUVECs showed that Neu5Ac inhibited cells viability in a time/dose-dependent manner, by then induced the activation of inflammation makers such as ICAM-1 and IL-1β. Mechanism study showed that the activation of excessive autophagy medicated by SQSTM1/p62 displayed an important role in endothelium inflammatory injury. Neu5Ac could modify SQSTM1/p62 as a sialylation protein, and then increase its level with ubiquitin binding, further inducing ubiquitination degradation and being involved in the excessive autophagy pathway. Inhibition of sialylation by P-3Fax-Neu5Ac, a sialyltransferase inhibitor, reduced the binding of SQSTM1/p62 to ubiquitin. Together, these findings indicated that Neu5Ac increased SQSTM1/p62-ubiquitin binding through sialylation modification, thereby inducing excessive autophagy and subsequent endothelial injury. Inhibition of SQSTM1/p62 sialylation might be a potential strategy for preventing such disease with high levels of Neu5Ac in circulation.

Sialic acid: an attractive biomarker with promising biomedical applications

This broad, narrative review highlights the roles of sialic acids as acidic sugars found on cellular membranes. The role of sialic acids in cellular communication and development has been well established. Recently, attention has turned to the fundamental role of sialic acids in many diseases, including viral infections, cardiovascular diseases, neurological disorders, diabetic nephropathy, and malignancies. Sialic acid may be a target for developing new drugs to treat various cancers and inflammatory processes. We recommend the routine measurement of serum sialic acid as a sensitive inflammatory marker in various diseases.

Sialic acid as a potential biomarker for cardiovascular disease, diabetes and cancer

Cardiovascular disease (CVD), diabetes and cancer pose increasing global healthcare burdens. New biomarkers could enable earlier diagnosis of these diseases, leading to more effective treatment and lower associated healthcare burden. Elevated sialic acid concentration in plasma and serum has been positively correlated with the presence of CVDs, diabetes and the development of malignant tumors. This article reviews the use of total sialic acid (TSA), bound sialic acid (BSA) and free sialic acid (FSA) as potential biomarkers for these diseases and makes a comparison with existing markers. Elevated sialic acid has been shown to be indicative of the pathogenesis of CVD, diabetes and malignant tumors. While not a specific marker for one disease there is promise in utilizing sialic acid as a marker for monitoring disease progression and effectiveness of treatment programs.

Evaluation of Serum Levels of Inflammation, Fibrinolysis and Oxidative Stress Markers in Coronary Artery Disease Prediction: A Cross-Sectional Study

Background

Coronary Artery Disease (CAD) has long been recognized as a global health issue. Inflammation, Fibrinolysis and Oxidative Stress play an important role in the disruption of plaques leading to CAD. Markers that reflect this pathophysiologic mechanism may have prognostic value.

Objective

To estimate the serum concentrations of high-sensitivity C-reactive protein (hs-CRP), sialic acid (SA), vitronectin (VN), plasminogen activator inhibitor-1 (PAI-1), oxidized low density lipoprotein (OX-LDL) and malondialdehyde (MDA) with significant prognostic value in patients with CAD.

Methods

The markers included, hs-CRP, SA, VN, PAI-1, OX-LDL and MDA, were compared between 160 angiographically diagnosed CAD patients and 20 age- and sex-matched healthy individuals. The subjects were divided into 4 groups according to angiography results, and association between all risk factors of CAD was studied. Serum levels of SA, VN, PAI-1, and OX-LDL were measured by enzyme-linked immunosorbent assay (ELISA); MDA was measured based on reaction with thiobarbituric acid (TBA); and hs-CRP level was estimated by immunoturbidimetry using a commercial kit. The diagnostic value of these variables was further assessed by ROC curve analysis. Multiple logistic regression was used to evaluate the diagnostic power of the combination. Furthermore, p < 0.05 was considered as significant.

Results

Serum levels of hs-CRP, SA, VN, PAI-1, and OX-LDL were significantly higher in patient groups compared to control group (p < 0.001). Using both normal and CAD patients as subjects, ROC analysis was performed. The cutoff for OX-LDL, MDA, PAI-1, VN, hs-CRP and SA was 2.67 (ug/mL), 5.49 (mmol/mL), 67 (ng/mL), 254 (ng/mL), 3.4 (mg/dL), 7/89 (mg/dL), respectively. Eventually, the complete diagnostic efficacy was classified as: SA, hs-CRP, PAI-1, OX-LDL, MDA and VN.

Conclusion

Serum levels SA, hs-CRP, VN, PAI-1, OX-LDL and MDA may be predictive of adverse cardiovascular outcomes. Interestingly, these analyses can help as diagnostic and monitoring markers in CAD patients.

Plasma Myeloperoxidase and Total Sialic Acid as Prognostic Indicators in Acute Coronary Syndrome

INTRODUCTION

Acute Coronary Syndrome (ACS) is the leading cause of death worldwide. Oxidative stress and inflammation play important role in the destabilization of plaques leading to ACS. Markers which reflect this pathophysiologic mechanism may have prognostic value. Myeloperoxidase (MPO) and Sialic acid are markers of inflammation and oxidative stress. Both these markers are increased in patients with ACS. Their prognostic value in ACS is not well established.

AIM

To analyse the prognostic value of plasma myeloperoxidase and total sialic acid levels in patients with suspected acute coronary syndrome.

MATERIALS AND METHODS

A prospective study was conducted on 93 consecutively admitted patients with chest pain from July 2011 to September 2011. Plasma MPO and total sialic acid levels on admission were estimated spectrophotometrically. These were compared with extent of disease, development of complications during the hospital stay, left ventricular ejection fraction and mean duration of stay in hospital.

RESULTS

Plasma MPO and total sialic acid levels were significantly higher in patients with myocardial infarction than those with unstable and stable angina (p<0.001 and p<0.007 respectively). The levels of plasma MPO and sialic acid levels were significantly higher in patients who developed complications like heart failure, arrhythmias, renal failure during their stay in hospital (p<0.011 and p<0.006 respectively). Ejection fraction was significantly low in patients with high MPO levels (p<0.011).

CONCLUSION

In patients with ACS, plasma MPO and total sialic acid levels on admission could predict the development of complications during their hospital stay. MPO levels correlated with ejection fraction in patients with ACS.

Benefits of Zubex beyond glycemic control: Evidence of the antiatherogenic effect

OBJECTIVE

To determine the effect of Zubex (aqueous extract of Curcuma longa linn, Iron murakab, Eugenia jambolana, Lin seed or flflax seed, processed egg shell calcium and Asphaltum) on plasma sialic acid (PSA) along with cardiovascular (CV) risk factors in streptozotocin-induced diabetic rats.

METHODS

Thirty male albino rats were divided into groups (1-6) with 5 rats in each group. Group 1 and 2 served as normal control (NC) and diabetic control (DC), respectively, and were given normal saline only. Groups 3-5 were given Zubex in different doses 100-400 mg/(kg day). Group 6 received glibenclamide 600 μg/(kg day) orally as a reference drug. Fasting plasma glucose (FPG) and PSA levels were determined at baseline after every 2 weeks for 10 weeks. The other parameters including blood lipids and hepatic enzymes were determined at baseline and at the end of the study. Finally, the liver was subjected to histological examination.

RESULTS

Compared with DC group, Zubex treated groups showed signifificant decline in FPG levels (P<0.05). At the endpoint, the decrease in PSA concentration was significant (P<0.05) from baseline at the doses of 200 and 400 mg/(kg day) only and insignifificant at the dose of 100 mg/ (kg day). Statistically signifificant improvements were observed in blood lipids at the doses of 200 and 400 mg/kg (P<0.05) compared with DC; but, the improvement was insignifificant in low density lipoprotein-cholesterol and high density lipoprotein-cholesterol at the dose of 100 mg/ (kg day). Signifificant decreases were also found in hepatic enzyme levels at all the doses of Zubex (P<0.05). Histological examination showed marked improvement in streptozotocin induced liver injury after treatment of all the 3 doses of Zubex.

CONCLUSION

Zubex could ameliorate PSA and other diabetic complications effectively and may be a useful alternative/adjuvant in diabetes treatment.

Sialyltransferase7A, a Klf4-responsive gene, promotes cardiomyocyte apoptosis during myocardial infarction

Myocardial infarction (MI) is one major cause of heart failure through its induction of cardiomyocyte death. However, the molecular mechanisms associated with MI-induced cardiomyocyte apoptosis in the context of sialylation of heart are not yet understood. In this study, we found that sialyltransferase7A (Siat7A), one of the members of sialyltransferase family, was significantly increased in the ischemic myocardium, as well as in the human cardiomyocyte cell line AC16 under hypoxic condition. The Sialyl-Tn antigen (Neu5Acα2-6GalNAc-O-Ser/Thr) synthesized by Siat7A also increased in the AC16 cardiomyocytes following hypoxic stimulus. Increased Siat7A promoted cardiomyocyte apoptosis. The knockdown of Siat7A expression reduced cardiomyocyte apoptosis in both of vivo and vitro. Furthermore, the decreased extracellular signal-regulated kinase ERK1 and ERK2 (ERK1/2) activity was involved in the Siat7A-induced cardiomyocyte apoptosis. Notably, we showed that Krüppel-like factor 4 (Klf4), one of the transcription factors, specifically bound to the Siat7A promoter by ChIP assays. Deletion and mutagenesis analysis identified that Klf4 could transactivate the Siat7A promoter region (nt -655 to -636 bp). The upregulated Siat7A expression, which was paralleled by the increased Klf4 in the ischemic myocardium, contributed to cardiomyocyte apoptosis. Our study suggests Siat7A could be a valuable target for developing treatments for MI patients.

Lower hypoglycemic but higher antiatherogenic effects of bitter melon than glibenclamide in type 2 diabetic patients

Objective

Since antiquity bitter melon has been in use for treating diabetes but clinical trials show conflicting results about its usefulness. The present study aims to asses and compare the hypoglycemic and antiatherogenic effects as well as the safety of two different doses of bitter melon with glibenclamide.

Methods

A total of 95 participants were randomized into 3 groups; group I and group II received bitter melon (2 g/day and 4 g/day respectively) and group III received glibenclamide (5 mg/day) for 10 weeks. Glycemic control and antiatherogenic effects were determined by assessing glycohemoglobin (HbA1-c), fasting plasma glucose (FPG), 2 hour oral glucose tolerance test (OGTT), plasma sialic acid (PSA), systolic blood pressure (SBP), blood lipids and atherogenic index at different time periods.

Results

Compared to baseline, mean reduction in HbA1-c at the endpoint was significant among patients of group I, group II and group III (p ≤ 0.05, p ≤ 0.02 and p < 0.005 respectively) and same was the case for FPG (p ≤ 0.05, p < 0.04, p < 0.003 respectively), but the improvement in 2 hour OGTT was significant only in group III (p < 0.03). The decrease in PSA was observed only among group I and group II with the later showing significant reduction from baseline (p < 0.01). In group III, the level slightly increased. Parameters including blood lipids, atherogenic index, body weight and SBP improved among patients of group I and group II but deteriorated among group III patients.

Conclusions

Our study concludes that bitter melon has a weaker hypoglycemic effect but ameliorates the diabetes associated cardiovascular (CV) risk factors more effectively than glibenclamide.

Trial registration

The trial was registered with Naseer Teaching Hospital Clinical Trials Registry number GU2014492233.

The association of total sialic acid and malondialdehyde levels with metabolic and anthropometric variables in obesity

Serum sialic acid levels are abnormally high in pathological states that exhibit tissue destruction, tissue proliferation or inflammation. We measured total serum sialic acid levels in 139 women and 125 men. Subjects were divided into quartiles according to their body mass index (BMI): Q1 (18-24.9 kg/m(2)), Q2 (25-29.9 kg/m(2)), Q3 (30-39.9 kg/m(2)) and Q4 (> 40 kg/m(2)). The patients in Q1 constituted the control group. Serum sialic acid levels of subjects in Q2, Q3 and Q4 were significantly higher than those in Q1. Higher BMI quartiles also were associated with higher levels of serum glucose, insulin, total cholesterol, LDL-cholesterol, triglycerides, high-sensitivity C-reactive protein, malondialdehyde levels, waist circumference, blood pressure and homeostasis model assessment of insulin resistance in both women and men. Lower BMI quartiles were associated with higher levels of serum HDL-cholesterol levels in both women and men. We found positive associations among serum sialic acid levels, BMI and oxidative stress. Serum sialic acid also is related to some conventional cardiovascular risk factors including elevated lipid profile, increased blood pressure, increased serum glucose and insulin levels, and insulin resistance in obese people.

Mutation in ST6GALNAC5 identified in family with coronary artery disease

We aimed to identify the genetic cause of coronary artery disease (CAD) in an Iranian pedigree. Genetic linkage analysis identified three loci with an LOD score of 2.2. Twelve sequence variations identified by exome sequencing were tested for segregation with disease. A p.Val99Met causing mutation in ST6GALNAC5 was considered the likely cause of CAD. ST6GALNAC5 encodes sialyltransferase 7e. The variation affects a highly conserved amino acid, was absent in 800 controls, and was predicted to damage protein function. ST6GALNAC5 is positioned within loci previously linked to CAD-associated parameters. While hypercholesterolemia was a prominent feature in the family, clinical and genetic data suggest that this condition is not caused by the mutation in ST6GALNAC5. Sequencing of ST6GALNAC5 in 160 Iranian patients revealed a candidate causative stop-loss mutation in two other patients. The p.Val99Met and stop-loss mutations both caused increased sialyltransferase activity. Sequence data from combined Iranian and US controls and CAD affected individuals provided evidence consistent with potential role of ST6GALNAC5 in CAD. We conclude that ST6GALNAC5 mutations can cause CAD. There is substantial literature suggesting a relation between sialyltransferase and sialic acid levels and coronary disease. Our findings provide strong evidence for the existence of this relation.

Serum Levels of Glycoproteins are Elevated in Patients with Ovarian Cancer

Identification of reliable biomarkers for detection and staging of cancer and monitoring the outcome of anticancer therapy has been considered to be of high importance. We aimed to estimate the levels of serum glycoproteins, protein bound-hexose, protein bound hexosamine, protein bound fucose, protein bound sialic acid and protein bound carbohydrate in 32 ovarian cancer patients and compared them with the levels that found in 25 normal subjects. As compared to the normal subjects, all the four fractions of glycoproteins level were significantly elevated in ovarian cancer patients (p < 0.05). Chemotherapy in these patients significantly decreased the levels of serum glycoproteins (p < 0.05). Thus, high levels of serum glycoproteins in ovarian cancer patients could be due to abnormal protein glycosylation indicating malignant transformation of the cells.

A comparison of the effect of glitazones on serum sialic acid in patients with type 2 diabetes

Although management of hyperglycaemia represents one of the principal treatment goals of diabetes therapy, the high incidence of cardiovascular (CV) complications in diabetes also needs effective management. Therefore, the present study was designed to determine and compare the effect of glitazones on serum sialic acid (SSA), a known risk marker for CV disease, along with fasting plasma glucose (FPG), glycohaemoglobin (HbA1-c) and blood lipids, in overweight, previously only diet-treated patients with type 2 diabetes (n=60). The study was conducted for a period of 12 months. Significant improvement in FPG and HbA1-c were shown by both rosiglitazone (p<0.003 and p<0.001, respectively) and pioglitazone (p<0.005 and p<0.001, respectively), compared with baseline, and pioglitazone showed greater beneficial effects on other parameters monitored, significantly reducing total cholesterol (TC) (p≤0.05). Both the drugs showed a decrease in SSA and no significant differences were observed between the groups. However, the decrease was significant only in the pioglitazone-treated group at month 12 (p≤0.05), compared with baseline. A significant decrease in SSA by pioglitazone indicates its greater cardioprotective effect compared with rosiglitazone.

Serum and saliva sialic acid in periodontitis patients with and without cardiovascular disease

Serum total sialic acid (sTSA) has recently been shown to be a cardiovascular risk factor. However, there is little information about the role of sTSA and TSA in saliva in periodontitis, a chronic and inflammatory disease known to be a risk factor for cardiovascular disease (CVD). We aimed to investigate the changes in sTSA and TSA levels in saliva in patients having both periodontitis and CVD versus periodontitis patients without diagnosed CVD. The study group consisted of 26 patients with proven periodontitis and 26 controls with no diagnosed systemic disease but periodontitis. sTSA and saliva TSA levels were determined by the thiobarbituric acid method, and C-reactive protein (CRP) was evaluated by the nephelometric method. The severity of periodontitis has been determined by the community periodontal index of treatment needs (CPITN). TSA in blood and saliva and CRP levels in blood were significantly increased in CVD patients compared with the control group. CPITN ranged from 2 to 4 in both groups. Significant and positive correlations were found between sTSA and saliva SA levels in patients and controls and between tooth loss and TSA both in blood and saliva. Therefore, TSA in saliva may be a useful marker similar to sTSA in CVD patients.

Dietary selenium intake is negatively associated with serum sialic acid and metabolic syndrome features in healthy young adults

Low-grade and chronic inflammation related to excessive body weight can increase the risk for type 2 diabetes and cardiovascular disease, whereas the intake of antioxidant nutrients appears to produce anti-inflammatory effects. The purpose of this observational study was to assess the potential relationships between serum SA levels, metabolic syndrome features, and dietary selenium intake to test the hypothesis that this antioxidant micronutrient may also have anti-inflammatory properties in healthy young adults. Forty-three healthy participants with a mean age of 18.0 +/- 0.93 years and a mean body mass index of 22.2 +/- 2.7 kg/m(2) were enrolled. Anthropometric, body composition, and blood pressure determinations were measured as well as serum lipid profile, glucose, insulin, and SA concentrations. Nutritional intake was estimated by a computerized, validated semiquantitative food frequency questionnaire. The findings included a positive correlation between SA and triacylglycerol levels (r = 0.317, P = .038) and a trend to significance with the homeostatic model assessment of insulin resistance index (r = 0.297, P = .053). Moreover, subjects with higher dietary selenium intake showed statistically lower SA levels compared with subjects with lower dietary selenium intake (1.8 +/- 0.4 vs 2.1 +/- 0.4 mmol/L, P = .037), while dietary selenium negatively correlated with SA (r = -0.331, P = .030) and triacylglycerol levels (r = -0.312, P = .041). It can be concluded that a relationship of SA, an inflammatory marker, with metabolic syndrome features such as lipid profile impairment and insulin resistance has been envisaged. In addition, we report (apparently for the first time) a negative association between SA and selenium intake, a recognized antioxidant trace element, in healthy young subjects, reinforcing the view of selenium as a potential anti-inflammatory nutrient.

Relationship between plasma sialic acid and fibrinogen concentration and incident micro- and macrovascular complications in type 1 diabetes. The EURODIAB Prospective Complications Study (PCS)

AIMS/HYPOTHESIS

Type 1 diabetes is associated with an increased risk of vascular complications. This increased risk could be explained by sialic acid and/or fibrinogen. It is also not clear what explains the abolition of sex-related differences affecting risk of CHD in the presence of type 1 diabetes. Therefore, we examined whether fibrinogen and sialic acid are related to incident micro- and macrovascular complications in patients with type 1 diabetes.

METHODS

A subset (n=2329) of the EURODIAB Prospective Complications Study was analysed. Sialic acid and fibrinogen concentrations were measured at baseline. The main outcomes after 7 years were development of albuminuria, retinopathy, neuropathy and CHD.

RESULTS

Univariable and multivariable models using Cox proportional survival analyses showed that an SD unit increase in sialic acid and fibrinogen levels was significantly associated with CHD in men only. Adjusted standardised hazard ratios (sHRs) were 1.50 (95% CI 1.05-2.15) and 1.40 (95% CI 1.06-1.86) for sialic acid and fibrinogen, respectively. Initial associations between (1) sialic acid and incident retinopathy [standardised odds ratio (sOR) men 1.68, 95% CI 1.10-2.57], (2) fibrinogen and retinopathy (sOR women 1.37, 95% CI 1.06-1.78) and (3) sialic acid and neuropathy (sOR men 1.37, 95% CI 1.06-1.77) were shown, but became non-significant in multivariable models.

CONCLUSIONS/INTERPRETATION

Sialic acid and fibrinogen are strong predictors of CHD in men with type 1 diabetes, beyond the effect of established risk factors. The associations found with microvascular complications were not independent of other risk factors.

C-reactive protein and interleukin-18 levels in relation to coronary heart disease: prospective cohort study from Busselton Western Australia

BACKGROUND

Elevated levels of inflammatory markers are associated with incident coronary heart disease (CHD), but it remains controversial whether these markers provide incremental predictive value to conventional risk factors. We investigated the relationship between C-reactive protein (CRP) and interleukin-18 (IL-18) levels and risk of CHD in men and women without initial cardiovascular disease.

METHODS

A prospective case-cohort design over the period 1981-2001 involving 253 incident CHD cases and a random sub-cohort of 441 subjects was used. Cox proportional hazards regression was used to estimate the relative risks (RRs) of CHD for continuous and tertiles of CRP and IL-18 after controlling for conventional risk factors.

RESULTS

The multivariate-adjusted RR of CHD associated with one unit increase in log CRP in the overall population was 1.29 (1.07, 1.55; trend P=0.008). Men and women in the top compared to bottom third of CRP distribution had an adjusted RR for CHD of 1.65 (1.03-2.65; P=0.036). The multivariate RR for continuous log IL-18 was 1.34 in men, 1.63 in women and 1.36 overall, and none reached statistical significance.

CONCLUSIONS

Baseline CRP but not IL-18 levels are independently predictive of future CHD. However CRP provides only modest additional predictive value over conventional risk factors and the benefit of a prevention strategy based on CRP still needs to be established.

Resialylation of sialic acid deficit vascular endothelium, circulating cells and macromolecules may counteract the development of atherosclerosis: a hypothesis

Deficit sialylation of vascular endothelium, circulating cells and macromolecules has been associated with the development of atherosclerosis. On the other hand, an elevated serum level of sialic acid is a long-lasting marker of atherosclerosis and complications from atherosclerosis. One may speculate that the inverse associations with atherosclerosis risk are due to some common underlying cause. One mission for the elevated serum sialic acid level might be to act as a substrate for resialylation of sialic acid deficit structures and thereby counteract the atherosclerotic process.

Sialic acid is an inflammation marker associated with a history of deep vein thrombosis

INTRODUCTION

Deep vein thrombosis (DVT) induces a systemic chronic inflammation and it has been associated with atherosclerosis. Increased levels of total sialic acid (TSA) have been shown to correlate with inflammation and atherosclerotic processes. The aim of this study was to investigate whether or not increased levels of TSA are associated with a history of DVT and with inflammation and coagulation markers, as well as with the lipid profile.

MATERIALS AND METHODS

TSA, fibrinogen, C-reactive protein (CRP), fibrin D-dimer (D-dimer), prothrombin fragment 1+2 (F1+2), endogenous thrombin generation, cholesterol and triglycerides were measured in 68 patients who had suffered, in the previous 6-12 months, a first episode of idiopathic DVT, and in 68 age- and sex-matched healthy subjects.

RESULTS

Levels of TSA, fibrinogen, CRP and D-dimer observed in patients were significantly higher than those detected in healthy subjects. TSA positively correlated with fibrinogen (R=0.47, p<0.01), cholesterol (R=0.46, p<0.01), triglycerides (R=0.38, p<0.01) and CRP (R=0.28, p<0.05). The logistic regression analysis confirmed that both high fibrinogen (> or =340 mg/dl) and cholesterol (> or =267 mg/dl) levels significantly and independently influence the TSA concentration. TSA levels above the 95th percentile of controls (>72 mg/dl) were detected in 33% of patients (OR=8.9; p<0.0001; 95% CI 2.4 to 31.7).

CONCLUSIONS

Patients with a history of DVT had associated high levels of TSA. In these patients, TSA correlated to markers of inflammation activity and lipid profile. Thus, TSA appears to be a useful vascular inflammatory marker in idiopathic DVT.

Transcriptional alterations in the left ventricle of three hypertensive rat models

Left ventricular hypertrophy (LVH) is commonly associated with hypertension and represents an independent cardiovascular risk factor. The aim of this study was to test the hypothesis that the cardiac overload related to hypertension is associated to a specific gene expression pattern independently of genetic background. Gene expression levels were obtained with microarrays for 15,866 transcripts from RNA of left ventricles from 12-wk-old rats of three hypertensive models [spontaneously hypertensive rat (SHR), Lyon hypertensive rat (LH), and heterozygous TGR(mRen2)27 rat] and their respective controls. More than 60% of the detected transcripts displayed significant changes between the three groups of normotensive rats, showing large interstrain variability. Expression data were analyzed with respect to hypertension, LVH, and chromosomal distribution. Only four genes had significantly modified expression in the three hypertensive models among which a single gene, coding for sialyltransferase 7A, was consistently overexpressed. Correlation analysis between expression data and left ventricular mass index (LVMI) over all rats identified a larger set of genes whose expression was continuously related with LVMI, including known genes associated with cardiac remodeling. Positioning the detected transcripts along the chromosomes pointed out high-density regions mostly located within blood pressure and cardiac mass quantitative trait loci. Although our study could not detect a unique reprogramming of cardiac cells involving specific genes at early stage of LVH, it allowed the identification of some genes associated with LVH regardless of genetic background. This study thus provides a set of potentially important genes contained within restricted chromosomal regions involved in cardiovascular diseases.

Sialic acid: a novel marker of cardiovascular disease?

The global burden posed by cardiovascular disease (CVD), due to a rising incidence of known risk factors, underlines an urgent need to identify other potential risk factors. Sialic acid (SA), an abundant terminal monosaccharide of glycoconjugates, is a possible risk factor for CVD. Although large-scale epidemiological surveys have shown that serum total sialic acid (TSA) is positively associated with mortality from coronary artery disease (CAD) and stroke, studies investigating the correlation between serum TSA and the severity of atherosclerosis are conflicting. Clinical and epidemiological studies indicate that serum TSA is a marker of a sustained inflammatory response in CVD, rather than causal in nature. Data also indicates ethnic variation in baseline TSA. This article reviews current methods for determining serum TSA and evidence supporting serum TSA as a risk factor for CVD. Potential mechanisms for this role are examined. The use of serum TSA as a marker of atherosclerotic disease is evaluated.

Sialic acid in cardiovascular diseases

Sialic acid, the acylated derivatives of 9-carbon sugar neuraminic acid, present as terminal component of oligosaccharide chains of many glycoproteins and glycolipids, has been recognized to be involved in the regulation of a great variety of biological phenomena. Studies have shown that serum sialic acid predicts both coronary heart disease and stroke mortality and reflects the existence or activity of an atherosclerotic process. Most of the studies have shown an elevation in serum sialic acid concentration in coronary heart disease and a positive correlation between the raised serum sialic acid and the severity of the coronary lesions is observed. However, a few contradictory reports are also available. Racial differences in serum sialic acid have also been reported and correlated with international differences in the prevalence of atherosclerosis. Reduced sialic acid content of platelets, erythrocytes and lipoproteins may play important role in the pathogenesis of atherosclerosis. Elucidation of the mechanism of alternation in sialic acid concentration may throw more light on its potential clinical utility. Hence more studies are needed to designates sialic acid as a cardiovascular risk factor/marker.