Serum concentrations of total sialic acid and sialoglycoproteins in relation to coronary heart disease risk markers

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.

Correlations of sialic acid with glycated hemoglobin A1c and glycemia in postmenopausal women with type-2 diabetes mellitus

For women in the postmenopausal period, age-related changes in the hormonal status are associated with a higher risk for type-2 diabetes and its complications. The tissue injury caused by diabetic vascular complications can induce a release of sialic acid (SA) into the general circulation leading to increased levels. The present study is a cross-sectional single center study of 77 women in the postmenopausal period. The subjects selected for the study were divided into two groups: i) The control group, which included postmenopausal women without type-2 diabetes mellitus (n=27); and ii) a group of postmenopausal women diagnosed with type-2 diabetes (n=50). By analyzing how the serum values of SA were correlated with glycemia and glycated hemoglobin in the subjects with diabetes, it was determined that both parameters exhibited a strong positive correlation (P<0.0001) in the group with type-2 diabetes. Therefore, SA may be considered as a potential marker for the screening, diagnosis or prognosis of type-2 diabetes for postmenopausal women.

Estimation of Sialic Acid and IL10 Levels in Stage 1 and 2 Periodontitis Patients

Objective

The role of biomarkers in staging and grading periodontal disease has become detrimental in relation to the overall treatment plan. This study aimed at evaluating and comparing the role of sialic acid and IL10 in the early and moderate stages of periodontitis.

Materials and Methods

Patients were selected according to the assessment of pocket depth and radiographic bone loss. Bone loss was calculated as <15% for stage 1 and 15–33% for stage 2. Salivary samples were collected using spit technique 2 hrs post consumption of food. The unstimulated saliva was collected in a sterile graduated container every minute for 5–8 minutes. IL10 estimation was done using ELISA, and sialic acid estimation was done using the diphenylamine method. The variables for the three groups were assessed using ANOVA, and intragroup comparisons for quantitative data were evaluated using the post hoc Bonferroni test (P < 0.05).

Results

On comparing sialic acid levels among the three groups, stage 2 showed the highest mean (8.61) compared with the other two groups and was highly significant (P < 0.001). On the contrary, IL10 when compared to stage 1 and 2 periodontitis revealed insignificant change.

Conclusion

The value of IL10 was higher as patients progressed from health to periodontitis.

Effect of Non-Surgical Periodontal Therapy on the Serum Sialic Acid Levels in Diabetic Patients with Periodontitis

Sialic acid (SA), a family of acetylated derivatives of neuraminic acid, an acute phase reactant by itself. It usually occurs as a terminal component at the non-reducing end of carbohydrate chains of glycoproteins and glycolipids. SA participates in multiple physiological functions, such as cell-to-cell interactions, cell migration and proliferation. Diabetes mellitus (DM) is a chronic metabolic disorder characterized by rise in blood glucose level. Periodontitis is a chronic inflammatory disease of the periodontal tissue, leading to destruction of bone surrounding the tooth and ultimately tooth loss. There is a two way relationship between diabetes mellitus and periodontitis. Periodontitis is the sixth complication of diabetes along with retinopathy, nephropathy, neuropathy, macrovascular disease, and altered wound healing. Inflammatory mediators like interleukin-6 and tumor necrosis factor-alpha produced during periodontal inflammation can interfere with the actions of insulin receptors and worsen the glycemic control of diabetic patients. Periodontitis is a major cause of tooth loss, affecting over 300 million people and bacteria associated with periodontitis are also linked with systemic problems like endocarditis, atherosclerosis. Recent work has highlighted a major role for the host sugar sialic acid in the biofilm physiology and host-pathogen interactions of T. forsithya, a key periodontal pathogen. There exists a need for a biomarker, for early detection of disease evolution and more robust therapy efficacy measurements. Serum sialic acids were estimated in Indian population by diphenylamine method and Thiobarbituric acid method. The average values were 68 ± 2.6 mg percent by DPA method and 56 ± 5 mg percent by TBA (thiobarbituric acid assay) method. Age and sex showed no influence on serum sialic acid level. Objectives of the present study was to compare (TSSA) level in healthy subjects, subjects with (CMP) with and without (NIDDM) and its effect on non-surgical periodontal therapy. In the present study, the participants were divided into three groups: Group A, B and C. Group A consists of systemically healthy subjects, Group B consists of subjects with (CMP) while Group C consists of subjects with (CMP) with (NIDDM) and results of this study indicated that, at baseline, there were significant differences between Group A, B and Group C with respect to all the clinical parameters, including (GI), (OHI-S), (PPD), (CAL), (TSSA) and (HbA1c) levels. Thus (TSSA) level could be considered as novel biomarker in the progression of periodontal disease and diabetic status. Periodontitis could be considered as a potential, modifiable, and independent risk factor for the development of diabetes. Early detection of elevated (TSSA) level may help in interpreting the progression of periodontitis, risk of development of diabetes mellitus in future and also to prevent complications.

Evaluation of prolidase activity and oxidative stress in patients with oral lichen planus and oral lichenoid contact reactions

OBJECTIVE

The aim of this study was to evaluate prolidase activity and oxidative stress in patients with oral lichen planus (OLP) and oral lichenoid contact reactions (OLCR) using serum and salivary samples and to compare these biomarkers with each other as well as with a group of healthy subjects in order to be able to opine their role in the estimation of OLP and OLCR.

PATIENTS AND METHODS

Eighteen recently diagnosed patients with OLP, 32 patients with OLCR and 18 healthy controls with matched periodontal status were recruited to the study. Prolidase activity, lipid peroxidation product malondialdehyde (MDA), sialic acid (SA), and advanced oxidation protein products (AOPPs) levels in both serum and saliva were determined. Additionally, salivary flow rate and its buffering capacity were estimated. Statistical analyses were performed using the chi-square test, t-test, Mann-Whitney U-test, and Spearman's rho correlation coefficient.

RESULTS

No statistically significant differences were observed between the study groups and the control group regarding to the basic characteristics and the periodontal status (P > 0.05). There were no statistically significant differences between OLP and OLCR groups regarding to the distribution of lesions' type, severity, and location (P > 0.05). No significant differences were found between the two study groups with regard to Prolidase activity, MDA, SA, and AOPPs (P ˃ 0.05), whereas statistically significant differences were found between the two study groups and the control group with regard to all evaluated parameters except of serum prolidase (P ˂ 0.01). Moderate correlation was found between salivary MDA and the OLP/OLCR lesion severity, whereas a weak correlation was observed between serum SA and the OLP/OLCR lesion severity (P ˂ 0.05).

CONCLUSIONS

The findings of this study suggest an increased prolidase activity and oxidative stress and imbalance in the antioxidant defense system in biological fluids of patients with OLP and OLCR when compared with the healthy subjects. Both OLP and OLCR patients revealed almost similar prolidase activity and oxidative stress levels although these two conditions have different etiopathogenesis.

Estimation of salivary and serum total sialic Acid levels in periodontal health and disease

BACKGROUND

Chronic gingivitis and periodontitis are inflammatory diseases. An important function of host sialic acid is to regulate innate immunity. The aim of the study was to assess the concentration of Total sialic acid (TSA) in saliva and serum and also to find out their association if any, in periodontal health and disease.

MATERIALS AND METHODS

A total of 90 subjects were clinically examined and distributed into three groups (n=30) according to the periodontal status namely healthy, chronic gingivitis and chronic periodontitis.Clinical measurements including probing depth, clinical attachment level, gingival index, oral hygeine index were recorded .TSA concentration was determined in saliva and serum of all subjects.

RESULTS

In healthy group the mean salivary TSA level was 39.05mg/dl ±6.35(p<0.0001), mean serum TSA level was 49.75 mg/dl ± 4.87 (p<0.0001). In the chronic gingivitis group the mean salivary TSA level was 68.23 mg/dl ± 2.71 (p<0.0001), mean serum TSA level was 65.65 mg/dl ±3.56 (p<0.0001). In the chronic periodontitis group the mean salivary TSA was 81.33 mg/dl ±3.94 (p<0.0001), mean serum TSA level was 75.98 mg/dl ±3.58 (p<0.0001).

CONCLUSION

The present data indicates that salivary & serum TSA levels can differentiate between chronic periodontitis patients and normal individuals. Thus it can be used as an adjunct to diagnose, monitor response to therapy, to determine the current periodontal disease status and to assess the treatment outcomes.

Birth weight, season of birth and postnatal growth do not predict levels of systemic inflammation in Gambian adults

Objectives

Studies testing whether systemic inflammation might lie on the causal pathway between aberrant fetal and post-natal growth patterns and later cardiovascular disease have been inconclusive, possibly due to the use of single markers of unknown predictive value. We used repeated measures of a comprehensive set of inflammatory markers to investigate the relationship between early life measures and systemic inflammation in an African population.

Methods

Individuals born in three rural villages in The Gambia, and for whom early life measurements were recorded, were traced (n = 320). Fasting levels of eight inflammatory markers (C-reactive protein, serum amyloid A, orosomucoid, fibrinogen, α 1-antichymotrypsin, sialic acid, interleukin-6 and neopterin) were measured, and potential confounding factors recorded. The association between early life measurements and systemic inflammation was assessed using regression analysis.

Results

Levels of most markers were unrelated to early growth patterns. In analyses adjusted for age and sex, more rapid growth between birth and 3 months of age was associated with higher levels of fibrinogen, orosomucoid, and sialic acid. These relationships persisted after further adjustment for body mass index but after full adjustment only the association with fibrinogen remained.

Conclusions

This study provides little evidence that size at birth or growth in early infancy determine levels of inflammatory markers in young Gambian adults. Am. J. Hum. Biol. 25:457–464, 2013. © 2013 Wiley Periodicals, Inc.

Salivary lipid peroxidation and total sialic acid levels in smokers and smokeless tobacco users as Maraş powder

Maraş powder (MP), a different type of smokeless tobacco (ST) and prepared from a tobacco of species Nicotiana rustica Linn, is widely used in Turkey. We aimed to investigate the effects of MP on salivary total sialic acid (TSA) and malondialdehyde (MDA) levels and to compare these parameters in smokers and MP users (MPUs). The salivary TSA and MDA concentrations were significantly higher in the smokers and MPU than those of control subjects and also in MPU than that of smokers. We have also observed that as the number of cigarettes consumed and MP amount increases, TSA and MDA levels increase too. In smokers, MDA values were significantly correlated with the number of cigarettes smoked and the duration of smoking. In MPU, both MDA and TSA levels were significantly correlated with the duration of MP use and the amount of daily consumed MP. We have concluded increased salivary TSA and MDA levels associated in MPU and smokers. Results can help to evaluate harmful effects of these habits. It is important to point out that bigger change in the measured parameters has been observed for MP use. This observation may be an important indication of harmful effects of ST use as MP.

Smoking and atherosclerotic cardiovascular disease: part II: role of cigarette smoking in cardiovascular disease development

Potential mechanisms and biomarkers of atherosclerosis related to cigarette smoking - a modifiable risk factor for that disease - are discussed in this article. These include smoking-associated inflammatory markers, such as leukocytes, high-sensitivity C-reactive protein, serum amyloid A, ICAM-1 and IL-6. Other reviewed markers are indicative for smoking-related impairment of arterial endothelial function (transcapillary leakage of albumin, inhibition of endogenous nitric oxide synthase activity and reduced endothelium-dependent vasodilation) or point to oxidative stress caused by various chemicals (cholesterol oxidation, autoantibodies to oxidized low-density lipoprotein, plasma levels of malondialdehyde and F(2)-isoprostanes and reduced antioxidant capacity). Smoking enhances platelet aggregability, increases blood viscosity and shifts the pro- and antithrombotic balance towards increased coagulability (e.g., fibrinogen, von Willebrand factor, ICAM-1 and P-selectin). Insulin resistance is higher in smokers compared with nonsmokers, and hemoglobin A1c is dose-dependently elevated, as is homocysteine. Smoke exposure may influence the kinetics of markers with different response to transient or chronic changes in cigarette smoking behavior.

Serum sialic acid changes in non-insulin-dependant diabetes mellitus (NIDDM) patients following bitter melon (Momordica charantia) and rosiglitazone (Avandia) treatment

Diabetes mellitus is associated with an increase in sialic acid concentration along with other complications. Sialic acid changes in NIDDM patients were investigated following bitter melon (55 ml/24h) and rosiglitazone (4 mg/24h) treatment. A total of 25 patients of both sexes were used in each experimental group. Patients following bitter melon treatment showed no significant difference of serum sialic acid (57.95+/-4.90 vs. 57.6+/-5.56 mg/dl, p=0.17) and serum glucose concentration (93.7+/-9.63 vs. 88.35+/-6.31 mg/dl, p=0.78) as compared to control subjects. However, the concentration of total cholesterol was significantly high in these patients as compared to control subjects (192+/-14.23 vs. 170.6+/-15.1mg/dl, p<0.03) but within normal range (160-200mg/dl), suggesting the significant hypoglycemic and lipid-lowering properties of bitter melon. The patients following rosiglitazone treatment showed a significant increase of serum sialic acid concentration (60.2+/-5.80 vs. 57.6+/-5.56 mg/dl, p=0.01) along with glucose (112+/-6.2 vs. 88.35+/-6.31 mg/dl, p<0.04) and total cholesterol concentration (216.45+/-20.2 vs. 170.6+/-15.1mg/dl, p<0.01) as compared to control subjects. In addition six of the patients had retinopathy, two of whom were suffering also from myocardial infarction and they still had a higher serum sialic acid (61.05+/-1.20mg/dl), glucose (187+/-2.11 mg/dl), total cholesterol (239.10+/-5.04 mg/dl) and triglyceride (183+/-4.14 mg/dl) concentration, indicating a poor response of these patients to rosiglitazone. Comparison of serum sialic acid concentration of patients, following bitter melon and rosiglitazone treatment revealed no significant difference but the study showed that bitter melon could be more effective in the management of diabetes and its related complications as compared to rosiglitazone.

Association between protein bound sialic acid and high sensitivity C-reactive protein in prehypertension: a possible indication of underlying cardiovascular risk

The global burden posed by cardiovascular disease due to a rising incidence of known risk factors like essential hypertension underlines an urgent need to identify other potential risk factors like dyslipidemia, elevated levels of high-sensitivity CRP (hsCRP), Apo-B, and sialic acid in prehypertensive subjects. This study sought to examine the possible alteration in the levels of hsCRP, plasma protein bound sialic acid, and other lipid risk factors and the possible interactions among these parameters in prehypertensive subjects. Forty prehypertensive and 34 normotensive male subjects were enrolled in the study. Lipid profile, hsCRP, Apo-B, sialic acid, and lipid risk ratios were estimated in both the groups. There was no significant difference between fasting glucose and BMI in either group. The levels of total cholesterol, triglycerides, direct LDL-cholesterol, non-HDL cholesterol, and Apo-B were significantly increased in prehypertensive subjects compared with controls. The risk ratios calculated as direct LDL-cholesterol/Apo-B, total cholesterol/HDL-cholesterol, non-HDL-cholesterol/HDL-cholesterol were significantly elevated in prehypertensive subjects. There was also a significant increase in hsCRP and protein bound sialic acid in prehypertensive subjects in comparison with normotensive subjects. Correlation analysis revealed a significant association between the protein bound sialic acid with hsCRP, LDL cholesterol, and LDL-C/Apo-B. The findings of the present study suggest that in prehypertension, there is an association between protein bound sialic acid and hsCRP that reflects the clustering of cardiovascular risk factors in these subjects.

Levels of serum sialic acid and thiobarbituric acid reactive substances in subjects with impaired glucose tolerance and type 2 diabetes mellitus

Cardiovascular disease is a common cause of death for diabetic patients. High sialic acid levels (SA) and increased oxidative stress are important factors for cardiovascular diseases. We aimed to research whether SA and thiobarbituric acid reactive substances (TBARS) levels are associated with the degree of the diabetic regulation and investigate if SA and TBARS levels can be controlled with the regulation of the blood glucose levels. A total of 179 subjects were included in the study. Three groups, which were comprised of subjects with type 2 diabetes mellitus (DM) (DM group [DMG], n=149), impaired glucose tolerance (IGT) (IGT group [IGTG], n=15), and normal oral glucose tolerance (NGT) (NGTgroup [NGTG], n=15) were constituted. Glucose, cholesterol, high-density lipoprotein (HDL) and glycated hemoglobin (HbA1C), SA, and TBARS were measured in the sera of the patients. SA and TBARS levels were significantly increased in subjects with type 2 DM (P<0.001 for both). SA concentrations showed significant correlation with triglycerides (r=0.229; P<0.05), fasting glucose (r=0.508; P<0.01), 2-hr postprandial glucose (r=0.455; P<0.01), and HbA1C (r=0.467; P<0.01), and there was a positive correlation between TBARS and HbA1C (r=0.251; P<0.01). Diabetic patients were found to have higher risk for inflammation and oxidative stress. The regulation of blood glucose levels may contribute to the decline of both SA and TBARS levels.

Platelet and White Blood Cell Counts Are Elevated in Patients With the Metabolic Syndrome

Platelet and white blood cell counts are higher among some insulin-resistant patients and may contribute to atherothromboembolic complications. Metabolic syndrome patients are insulin resistant, often hypertensive, and at high cardiovascular disease risk, yet the relationship of platelets to the metabolic syndrome is unknown. Platelet and white blood cell counts were obtained from 135 volunteers who had measurements of blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and glucose. A body mass index >30 kg/m2 served as a surrogate for increased waist circumference. Subjects were subdivided into three groups by the number of metabolic syndrome criteria, i.e., no metabolic syndrome risk factor (MS-0; n = 40), one or two metabolic syndrome risk factors (MS1-2; n = 61), and three to five metabolic syndrome risk factors (MS3-5; n = 34). Platelet counts were increased significantly from 226+/-8 to 257+/-8 and 276+/-10 (x10(3)/mm3) in the MS-0, MS1-2, and MS3-5 groups, respectively (p < 0.01), after adjustment for age, gender, ethnicity, total cholesterol, and low-density lipoprotein cholesterol. White blood cell counts were also increased across the three groups (5.4+/-0.2, 6.2+/-0.2, and 6.6+/-0.3 [x10(3)/mm3]; p < 0.01) after multivariate adjustment. Compared with patients with zero to two metabolic syndrome risk factors, metabolic syndrome patients have higher platelet and white blood counts, which may serve as markers of a prothrombotic and proinflammatory state and contributors to atherothromboembolic risk.

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.

Biochemical markers of alcoholism

Alcohol and alcohol-related diseases have become a major cause of death in Western countries. The most sensitive and specific of the commonly used biomarkers of alcohol intake are carbohydrate-deficient transferrin (CDT), and the combination of gamma-glutamyltransferase (GGT) and CDT. Other widely used laboratory markers are GGT, mean corpuscular volume of erythrocytes and the ratio of aspartate aminotransferase to alanine aminotransferase. Blood ethanol levels reveal recent alcohol use. However, more specific and sensitive biomarkers to improve the detection of excessive alcohol use at an early stage are needed. New biomarkers, not yet used in routine clinical work, include phosphatidylethanol, fatty acid ethyl esters, ethyl glucuronide, sialic acid, and acetaldehyde adducts.

Relationship between serum sialic acids, sialic acid-rich inflammation-sensitive proteins and cell damage in patients with acute myocardial infarction

The role of sialic acid (SA) in the pathogenesis of atherosclerosis and as a predictor of cardiovascular events has attracted much attention in recent years. However, most studies investigating the role of total and lipid-bound sialic acids (TSA and LSA) in the pathogenesis of atherosclerosis lack information on the reason for the elevated SA concentrations in coronary heart disease and myocardial infarction. Since the inflammation-sensitive proteins are glycoproteins with SA residues, an increase in their levels due to some type of acute-phase reaction or inflammation could be responsible for the elevated TSA levels in acute myocardial infarction (AMI). Elevated serum SA levels might also be due to either shedding or secretion of free SA from the cell or cell membrane surface if neuraminidase levels are increased, or to the release of cellular SA-containing glycolipids and/or glycoproteins into plasma from myocardial cells after AMI. The aim of the present study was to investigate both the possible role of SA-rich inflammation-sensitive proteins and the cell damage due to elevated serum TSA levels in AMI. A possible role of serum LSA as an indicator of the shedding or secretion of SA from the cell or cell membrane surface in AMI was also evaluated. The study included 38 subjects with AMI and 32 healthy volunteers. Serum TSA and LSA were determined using the methods of Warren and Katopodis, respectively. The concentrations of serum SA-rich inflammation-sensitive proteins, namely α

Serum total sialic acid levels in smokers and users of smokeless tobacco in form of oral powder (Maraş powder)

Smokeless tobacco (ST) is widely used as chewing tobacco and as oral snuff in the world. Also, in Kahramanmaraş, a city in Southern Turkey, ST used as 'oral powder' or 'Maraş Powder' is consumed widely instead of cigarette smoking. The aim of this study was to search the effect of ST use on serum total sialic acid (TSA) and to compare the serum TSA levels in smokers and ST users. The study was performed at the Department of Chemistry-Biochemistry, University of Kahramamaraş Sutcu Imam, Turkey, in 2003. Serum samples obtained from smokers (Group I), Maraş powder users (Group II), and healthy control subjects (Group III) who were nonsmokers and nonusers ST. Individuals who were smokers and ST users were classified into subgroups with respect to amount of consumed cigarette or oral powder. Serum TSA was measured with the Denny's colorimetric method. The TSA concentrations were significantly higher in the sera of smokers (p < 0.001) and Maraş powder users (p < 0.001) than those of control subjects. The mean serum TSA level was found to be lowest in the control group and highest in the Maraş Powder users. But, there was no significant difference in serum TSA levels between smokers and Maraş powder users (p > 0.05). We can conclude from the results obtained that serum TSA was affected by ST use as seen in smokers. This finding may be an indication of harmful effects of ST use as Maraş powder as well as cigarette smoking.

Discrimination ratio analysis of inflammatory markers: implications for the study of inflammation in chronic disease

To understand the role of inflammation in chronic disease it is important to have a reliable measure of habitual inflammatory status. A number of acute-phase response markers have been used as measures of inflammatory status, but the ability of a single measure to appropriately reflect habitual inflammatory status has not been assessed. This study compares the ability of different inflammatory markers to characterize habitual inflammatory status in overweight women. A single fasting blood sample was taken from 86 overweight women (mean body mass index [BMI], 35.2 kg/m2; range, 26.2 to 47.6 kg/m2) and a number of inflammatory markers (both acute-phase response markers and cytokines) were measured. A randomly selected subpopulation of 15 women attended on 2 further occasions for further blood samples. Using the subpopulation, discrimination ratios (DRs) were calculated for each inflammatory marker to assess the within-subject variability. The DRs were then used to determine the relationship between these markers, adjusted for within-subject variability, in the whole population. In this highly controlled experimental environment, interleukin-6 (IL-6), with a DR of 3.71, was the cytokine with the greatest ability to discriminate between subjects, suggesting that it is best able to characterize habitual inflammatory status. Sialic acid was the acute-phase response marker with the highest DR (3.16), and showed stronger correlations with other inflammatory markers, including C-reactive protein (CRP), than IL-6. This study suggests that use of some inflammatory markers, such as CRP, with large within-individual variability, will underestimate the relationship between inflammation and disease, and thus relationships between inflammation and chronic disease may be stronger than previously appreciated. Future studies should consider IL-6 or sialic acid to provide a more robust measure of inflammatory status.

Elevated sialic acid, but not CRP, predicts features of the metabolic syndrome independently of BMI in women

AIMS

C-reactive protein (CRP) is a predictor of many diseases including type II diabetes and cardiovascular disease. Fewer studies have similarly shown sialic acid (SA) to be a predictor of obesity-related diseases, but importantly SA shows less intra-individual variability than CRP and acts as an integrated marker of the activity of a number of acute-phase proteins. This study examines the association between both CRP and SA with individual and combined features of the metabolic syndrome.

SUBJECTS

In all, 257 women with a body mass index (BMI) ranging from 25.1 to 54.5 kg/m2 (geometric mean 33.1+/-5.8 kg/m2) and aged 19-71 y (mean 45.6+/-12.1 y) were studied. Subjects had no symptoms of intercurrent infection, known diabetes, treated dyslipidaemia, a chronic inflammatory condition, liver disease or malignancy.

RESULTS

Linear regression demonstrates that both CRP and SA were positively associated with weight, BMI, insulin resistance, dyslipidaemia and hypertension. There was a highly significant (P<0.0001) positive association of both SA and CRP with none, one, two, three or four features of the metabolic syndrome. For a 1 s.d. (4.0 mg/l) increase in CRP, there was a significant increased risk when comparing the odds of having metabolic syndrome (defined as three or more individual features) compared with the remainder of the population (odds ratio=1.7, P<0.0001), but this was not significant after adjustment for BMI. However, for a 1 s.d. (0.34 mmol/l) increase in SA, the odds of having metabolic syndrome compared with those without metabolic syndrome was 2.5 (P<0.0001), and persisted after additional adjustment for BMI (adjusted odds ratio=1.9, P<0.0001).

CONCLUSIONS

While SA and CRP are both univariately associated with individual features of the metabolic syndrome, SA, but not CRP, is significantly associated with the metabolic syndrome, independent of BMI. We conclude that SA identifies a subgroup of overweight individuals with an inflammatory phenotype, who are at the greatest risk of metabolic syndrome.

Diabesity: an inflammatory metabolic condition

Diabesity, that is to say, obesity-dependent diabetes, has emerged as a major public health problem. Though diabesity is basically explained by insulin resistance and pancreatic beta cell dysfunction, new paradigms have evolved to explain these alterations in the context of the modern epidemics of obesity and diabetes. Among these, the association of inflammation with obesity is an important component of the common soil from which diabetes and cardiovascular diseases (CVD) derive. This Review presents our epidemiological findings, based primarily on the ARIC Study, in the context of the other epidemiological studies supporting the inflammatory nature of diabetes, CVD and the metabolic syndrome. We also review the characteristics of the innate immune system, including the molecular interface of innate immunity with metabolism, components of which are responsible for the presence of a state of mild, chronic and systemic inflammation related to diabesity. Finally, we present obesity as an inflammatory condition, obesitis, and propose a conceptual framework that integrates the epidemiological findings with new provocative basic science results.

Association of serum sialic acid with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with type 1 diabetes

The aim of the present study was to investigate the relation of serum total sialic acid (TSA) concentrations with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with uncomplicated type 1 diabetes. This case-control study included 150 (57 males and 93 females) type 1 diabetic children aged 6 to 18 years matched by age and sex to 150 nondiabetic children as controls. Measured variables included weight, height, systolic, diastolic blood pressure, and biochemical variables: blood glucose, glycated hemoglobin (HbA(1C)), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), apolipoproteins (apo) A1 and B, and urine microalbumin. There was no significant difference between mean serum TSA of the type 1 diabetic children (671.0 mg/L) and their controls (663.7 mg/L). In diabetic children, mean serum TSA was significantly higher in females (699.1 mg/L) than in males (625.2 mg/L) (P =.003). Significant correlations were found between serum TSA and the cardiovascular risk factors TC (P =.002), TG (P <.001), and apo B (P =.008). TSA mean level was significantly higher in diabetic children with poor glycemic control (HbA(1C) > 9.0%; P =.015), raised TC (P =.013), raised TG (P =.014), and in children with family history of cardiovascular disease (CVD; P =.02). In conclusion, the study suggests that serum TSA levels were not elevated in young type 1 diabetic children as compared with controls. The study also confirmed significant correlation of TSA concentrations with CVD risk factors TC, TG, and apo B, and as such serum TSA may be considered as a marker for CVD risk, especially in diabetic patients. A long-term prospective study is recommended to ascertain the longitudinal relationship of serum TSA with the adverse metabolic changes in type 1 diabetic children as complications prevail.

Type 2 diabetes mellitus: a disease of the innate immune system? An update

A few years ago a hypothesis was proposed suggesting that elements of the innate immune system, such as acute phase reactants, contribute to the development of Type 2 diabetes mellitus. Acute phase reactants such as C-reactive protein and sialic acid may thus predict risk of developing Type 2 diabetes mellitus, as well as being markers of diabetes microvascular and macrovascular complications. This article discusses these issues.

Longevity-associated mitochondrial DNA 5178 A/C polymorphism influences effects of cigarette smoking on serum protein fraction levels in Japanese men

Mitochondrial DNA 5178 adenine/cytosine (mt5178 A/C) polymorphism is reportedly associated with longevity and susceptibility to age-related diseases in Japanese individuals. We previously reported an association between mt5178 A/C polymorphism and serum protein fraction levels in healthy Japanese women. An association between habitual smoking and serum protein fraction levels has also been reported previously. The aim of this study was to examine whether mt5178 A/C polymorphism influenced the effects of habitual smoking on serum protein fraction levels in 321 healthy Japanese men. In mt5178C genotype men, alpha-1 and alpha-2 globulin levels were higher in smokers than in nonsmokers (P<0.001, and P=0.002, respectively). The influence of smoking on these globulin levels depended on cigarette consumption. However, in mt5178A genotype men, no significant difference was observed in alpha-1 or alpha-2 globulin levels between smokers and nonsmokers. These results suggest that longevity-associated mt5178 A/C polymorphism may influence the effects of cigarette smoking on serum protein fraction levels in healthy Japanese men.

Total sialic acid and associated elements of the metabolic syndrome in women with and without previous gestational diabetes

OBJECTIVE

Inflammatory markers predict type 2 diabetes and relate to the metabolic syndrome. Gestational diabetes mellitus (GDM) predicts type 2 diabetes and may be part of this syndrome. To examine the association of inflammatory markers with GDM, we investigated total sialic acid (TSA) in women with and without previous GDM.

RESEARCH DESIGN AND METHODS

All women with GDM and a random sample of women from one center of the Brazilian Study of Gestational Diabetes were invited to return 7 years after their index pregnancy. After an interview, an oral glucose tolerance test and anthropometry were performed. A total of 46 women with and 50 women without previous GDM completed the protocol.

RESULTS

Mean TSA was significantly higher in women with (71.8 +/- 11.1 mg/dl) than without (67.5 +/- 9.8 mg/dl) previous GDM (P < 0.05). In a linear regression model, TSA was 4 mg/dl (P < 0.05) higher in women with previous GDM, after adjustment for BMI, fasting insulin sensitivity, and number of years spent in school. In a similar model, current 2-h plasma glucose levels were associated with higher TSA levels after adjustment for waist-to-hip ratio and the log of triglycerides. TSA was strongly correlated with individual components and aggregates (r = 0.55, P < 0.001) of the metabolic syndrome.

CONCLUSIONS

Increased TSA levels are associated with previous GDM and are strongly linked to the metabolic syndrome. These findings in young women suggest that a chronic mild systemic inflammatory response is an early feature of the metabolic syndrome and that GDM may be a window for its investigation.

The response of serum sialic acid and other acute phase reactants to an oral fat load in healthy humans

BACKGROUND

Elevated serum total sialic acid (TSA) has been shown to be associated with increased cardiovascular mortality. It has been postulated that atherogenesis is a postprandial phenomenon. We tested the hypothesis that serum TSA and other acute phase proteins, namely C-reactive protein (CRP) and fibrinogen, may be related to the postprandial state.

METHODS

Ten healthy male subjects, aged 24-48 years, were fed 62.5 g of total fat (saturates 12 g, monounsaturates 35.3 g and polyunsaturates 12.5 g) in the form of strawberry flavoured Calogen. Venous blood was sampled hourly for 5 h. Concentrations of serum triglyceride, TSA and acute phase proteins were measured.

RESULTS

Serum triglyceride concentration increased postprandially, peaking at 240 min. Serum CRP and plasma fibrinogen did not significantly increase after the oral fat load. However, serum TSA did increase from baseline (0.599+/-0.051 g/l) in response to the oral fat load, peaking at 120 min post-oral fat load (0.633+/-0.066 g/l, P<0.02). There was a significant correlation between serum TSA and plasma fibrinogen at baseline (rho=0.62, P=0.05) but not for serum CRP (rho=-0.22) or triglyceride (rho=0.21).

CONCLUSIONS

We conclude that serum TSA increases postprandially and this finding gives further insight as to why the former is considered to be a cardiovascular risk factor.

Chronic activation of the innate immune system may underlie the metabolic syndrome

CONTEXT

The metabolic syndrome is characterized by a clustering, in free-living populations, of cardiovascular and diabetes risk factors generally linked to insulin resistance, obesity and central obesity. Consonant with the well-established inflammatory pathogenesis of atherosclerotic disease, the metabolic syndrome is now being investigated in relation to its inflammatory nature.

OBJECTIVE

We present cross-sectional findings demonstrating that markers of inflammation correlate with components of the metabolic syndrome, and prospective findings of the ARIC Study indicating that markers of inflammation and endothelial dysfunction predict the development of diabetes mellitus and weight gain in adults. We present biological evidence to suggest that chronic activation of the innate immune system may underlie the metabolic syndrome, characterizing the common soil for the causality of type 2 diabetes mellitus and cardiovascular disease.

CONCLUSIONS

Better understanding of the role of the innate immune system in these diseases may lead to important advances in the prediction and management of diabetes and cardiovascular disease.

Circulating concentrations of C-reactive protein and total sialic acid in tobacco smokers remain unchanged following one year of validated smoking cessation

BACKGROUND

Elevated plasma concentrations of C-reactive protein (CRP) and total sialic acid (TSA) have been associated with increased cardiovascular risk. Additionally, levels of both CRP and TSA have been reported to be significantly elevated in smokers. However, it is not clear if the raised TSA and CRP levels noted in smokers are directly attributable to the smoking experience, or if they may be elevated due to a secondary mechanism(s), such as smoking-induced tissue inflammation.

SUBJECTS AND METHODS

We measured the plasma concentration of CRP and TSA in a group of smokers at baseline and following one year of validated smoking cessation (n = 30) and in a control group of tobacco users who continued to smoke over the year (n = 30).

RESULTS

The baseline concentration of TSA and CRP was 67.2 mg dL(-1) and 1.91 mg L(-1), respectively (n = 60). No significant dose-dependent relationship was noted between baseline CRP or TSA concentration and either plasma cotinine, expired-air CO or daily cigarette consumption. There was no difference in the mean change in CRP level in the quitters over one year (- 0.2 mg L(-1)) compared to the continuing smokers (+ 0.5 mg L(-1)), P = 0.80, or in the change in concentration of TSA in the quitters (- 2.7 mg dL(-1)) compared to the continuing smokers (+ 0.4 mg dL(-1)), P = 0.26.

CONCLUSIONS

As the circulating concentrations of both CRP and TSA remain unchanged following one year of smoking cessation, these results would suggest that the elevated levels noted in smokers are not directly attributable to tobacco use and are more likely to be elevated due to a secondary process that is yet to be established.

Fibrinogen, other putative markers of inflammation, and weight gain in middle-aged adults--the ARIC study. Atherosclerosis Risk in Communities

PURPOSE

Weight gain is an important risk factor for the development of the metabolic syndrome, and inflammatory mediators are strongly associated with this syndrome. Our aim was to investigate whether inflammation predicts the development of weight gain in populations.

RESEARCH METHODS AND PROCEDURES

We investigated selected markers of inflammation in the prediction of weight gain over an approximately 3-year period in a biethnic cohort of 13,017 men and women, 45 to 64 years of age, using multiple linear and logistic regression modeling.

RESULTS

In adjusted models, those in the highest quartile of fibrinogen gained, during the first 3 years of follow-up, an estimated 0.23 kg/year more than those in the lowest quartile (p < 0.001). Adjusted odds of a large (greater than the 90th percentile) weight gain for those in the highest quartile of fibrinogen were 1.65 (95% confidence interval [CI], 1.38 to 1.97) times those in the lowest quartile. Similarly adjusted odds ratios for a large weight gain for those with high levels of white blood cell count, factor VIII, and von Willebrand factor were 1.38 (1.14 to 1.67), 1.28 (1.08 to 1.53), and 1.28 (1.08 to 1.51), respectively.

DISCUSSION

Fibrinogen and other putative markers of inflammation predict weight gain in middle-aged adults. Given the known links between the inflammatory response and intermediary metabolism and the methodological strengths of the Atherosclerosis Risk in Communities (ARIC) cohort, these findings, though without immediate clinical applicability, suggest that inflammatory processes play a role in the development of the metabolic syndrome and cardiovascular disease in part through stimulation of weight gain.

Serum sialic acid in young type-1 diabetic patients

It is well established that serum total sialic acid (TSA) is elevated in patients with type-2 diabetes mellitus (NIDDM) compared to non-diabetics. However, it is not clear whether serum TSA is also elevated in type-1 diabetic patients (IDDM). Twenty-one type-1 patients were studied along with age and sex matched normal non-diabetic subjects (ten males and 11 females). Their ages were 24.8+/-3.4 years (20-30) and 23.5+/-3.9 years (18-30) respectively. The duration of diabetes mellitus was 12.6+/-6.7 years (1-24) with a HBA1c of 9.0+/-2.2% (6.0-14.9). There was no significant difference in serum TSA of the type-1 diabetic patients 689+/-107 mg/l versus 670+/-119 mg/l in the normal subjects. Nor was there a significant correlation between serum TSA with patient age (r = -0.31), urine albumin/creatinine ratio (ACR) (r = 0.25), HBA1c (r = 0.36), plasma random glucose (r = -0.04) or diabetes duration (r = -0.09) in the diabetic patients. However, there was a significant correlation between serum TSA and mean daily insulin dose (r = 0.51, P<0.02) and also serum cholesterol and triglyceride (r = 0.58, P<0.01 and r = 0.49, P<0.04, respectively) in the type-1 diabetic patients. In summary, we conclude that serum TSA is not elevated in young type-1 diabetic patients compared with normal age and sex matched control subjects. However, the relationship between serum TSA and serum lipids and also mean daily insulin dose merits further research.

No relationship between serum lipoprotein(a) and albumin concentrations in patients with acute phase response

The aim of this study was to investigate the relationship between lipoprotein(a) [Lp(a)] and albumin concentrations in the serum of patients with acute phase response (APR). We have compared the Lp(a) concentrations and apolipoprotein [apo(a)] phenotypes of 40 controls with those of 40 APR patients with normoalbuminaemia and 40 APR patients with hypoalbuminaemia. We have also compared concentrations of haptoglobin (Hp) and alpha 1-antitrypsin (AAT) containing a high sialic acid content, similar to Lp(a). The mean serum Lp(a) concentration (SD) of the 40 controls was 0.190 (0.142) g/L. The mean serum Lp(a) concentration was 0.358 (0.257) g/L (P < 0.001) in 80 APR patients. However, there was no difference in serum Lp(a) concentrations between the APR patients with hypoalbuminaemia [0.353 (0.268) g/L] and the APR patients with normoalbuminaemia [0.362 (0.249) g/L]. No significant difference was found in the distributions of apo(a) phenotypes between the controls, the APR patients with hypoalbuminaemia, and the APR patients with normoalbuminaemia (P = 0.183). In the APR patients, the serum concentrations of AAT and Hp were respectively 2.709 (0.822) g/L and 2.631 (1.340) g/L, whereas those of normal controls were respectively 1.422 (0.219) g/L (P < 0.001) and 0.956 (0.442) g/L (P < 0.001). In conclusion, the Lp(a) is one of the acute phase reactants whose synthesis concurrently increases with other APRs, especially those with a high sialic acid content. The increase of the serum Lp(a) concentrations in the APR patients is not related to serum albumin concentration.

Serum sialic acid and sialoglycoproteins in asymptomatic carotid artery atherosclerosis. ARIC Investigators. Atherosclerosis Risk in Communities

Serum total sialic acid (S-TSA) is a recently identified risk marker for atherosclerosis and cardiovascular mortality. The purpose of this study was to evaluate the influence of three sialic acid rich glycoproteins (orosomucoid, haptoglobin, and alpha1-antitrypsin) on the relationship between S-TSA and carotid atherosclerosis. The mean S-TSA was 0.045 g/l higher among cases than controls (P<0.001) in 310 45-64 year-old male and female pairs of carotid atherosclerosis cases and disease-free controls from the Atherosclerosis Risk in Communities (ARIC) Study. Also mean serum levels of the glycoproteins were significantly higher in cases compared to controls. In a conditional multiple logistic regression model with the glycoproteins as independent variables, orosomucoid was correlated most strongly with case control status. However, when incorporated into the mathematical model, S-TSA not only contributed additional information as to the risk of atherosclerosis; none of the three glycoproteins contributed further once S-TSA had been accounted for. Thus, some other source of serum sialic acid or variations in the degree of sialylation of glycoproteins may be essential for understanding the relation between S-TSA and atherosclerosis.

Markers of inflammation and prediction of diabetes mellitus in adults (Atherosclerosis Risk in Communities study): a cohort study

BACKGROUND

Type 2 diabetes mellitus and atherosclerotic cardiovascular disease have common antecedents. Since markers of inflammation predict coronary heart disease and are raised in patients with type 2 diabetes, we investigated whether they predict whether people will develop type 2 diabetes.

METHODS

12,330 men and women, aged 45-64 years, were followed up for a mean of 7 years. We analysed the association between different markers of acute inflammation and subsequent diagnosis of diabetes. In a subgroup of 610 individuals selected originally for an unrelated atherosclerosis case-control study, we also investigated diabetes associations with total sialic acid and orosomucoid, haptoglobin, and alpha1-antitrypsin.

FINDINGS

1335 individuals had a new diagnosis of diabetes. Adjusted odds ratios for developing diabetes for quartile extremes were 1.9 (95% CI 1.6-2.3) for raised white-cell count, 1.3 (1.0-1.5) for low serum albumin, and 1.2 (1.0-1.5) for raised fibrinogen. In the subgroup analysis, individuals with concentrations of orosomucoid and sialic acid of more than the median had odds ratios of 7.9 (2.6-23.7) and 3.7 (1.4-9.8), respectively. Adjustment for body-mass index and waist-to-hip ratio lessened the associations; those for white-cell count (1.5 [1.3-1.8]), orosomucoid (7.1 [2.1-23.7]), and sialic acid (2.8 [1.0-8.1]) remained significant.

INTERPRETATION

Markers of inflammation are associated with the development of diabetes in middle-aged adults. Although autoimmunity may partly explain these associations, they probably reflect the pathogenesis of type 2 diabetes.

Occurrence of sialic acids in healthy humans and different disorders

Sialic acid (SA), N-acetylated derivatives of neuraminic acid, play a central role in the biomedical functioning of humans. The normal range of total sialic acid (TSA) level in serum/plasma is 1.58-2.22 mmol L-1, the free form of SA only constituting 0.5-3 mumol L-1 and the lipid-associated (LSA) forms 10-50 mumol L-1. Notably, considerably higher amounts of free SA are found in urine than in serum/plasma (approximately 50% of the total SA). In inherited SA storage diseases such as Salla's disease, SA levels are elevated many times over, and their determination during clinical investigation is well established. Furthermore, a number of reports describe elevated SA levels in various other diseases, tentatively suggesting broader clinical utility for SA markers. Increased SA concentrations have been reported during inflammatory processes, probably resulting from increased levels of richly sialylated acute-phase glycoproteins. A connection between increased SA levels and elevated stroke and cardiovascular mortality risk has also been reported. In addition, SA levels are slightly increased in cancer, positively correlating with the degree of metastasis, as well as in alcohol abuse, diabetes, chronic renal failure and chronic glomerulonephritis. Several different mechanisms are assumed to underlie the elevated SA concentrations in these disorders. The apparent non-specificity of SA to a given disease limits the potential clinical usefulness of SA determination. In addition, some non-pathological factors, such as aging, pregnancy and smoking, may cause changes in SA concentrations. The absolute increases in SA levels are also rather small (save those in inherited SA storage disorders); this further limits the clinical potential of SA as a marker. Tentatively, SA markers might serve as adjuncts, when combined with other markers, in disease screening, disease progression follow-up, and in the monitoring of treatment response. To become clinically useful, however, the existing SA determination assays need to be considerably refined to reduce interferences, to be specific for certain SA forms, and to be more easy to use.

Erythrocyte disaggregation shear stress, sialic acid, and cell aging in humans

Erythrocyte aggregation, which plays an important role in the physiological behavior of blood fluidity, was found to be enhanced in hypertension and hypercholesterolemia. While the role of macromolecule bridging force has been widely described, cellular factors related to membrane sialic acid content, which might contribute to the negative charge of cell surface causing the repulsion of erythrocytes, have been less studied. Cell age-dependent changes in membrane sialic acid content (in micromoles per gram of integral membrane protein) were investigated in 24 normotensive and 24 hypertensive matched subjects, each divided into 2 identical subgroups according to a cutoff of 6.2 mmol/L serum cholesterol. A progressive and significant (P<0.001) decrease in membrane sialic acid content associated with an increase (P<0.001) of disaggregation shear rate threshold (laser reflectometry in the presence of dextran) were observed with increased erythrocyte density (erythrocytes fractionated by density using ultracentrifugation) in both normotensive and hypertensive groups regardless of the cholesterol level. However, disaggregation shear rate threshold was significantly higher and sialic acid content was lower (P<0.001) in both hypertensive and normotensive subjects with hypercholesterolemia compared with either normotensive or hypertensive subjects with low cholesterol, respectively. A high membrane sialic acid content variance, beginning in the younger erythrocytes, was due mainly to triglyceride and LDL cholesterol levels (R2=0.49 for low, R2=0.43 for middle, and R2=0.54 for high densities, ie, young, mean, and senescent erythrocytes, respectively). We conclude that an early decrease in erythrocyte sialic acid content may influence the rheological properties of blood by increasing the adhesive energy of erythrocyte aggregates.

Lack of association between ferritin level and measures of LDL oxidation: the ARIC study. Atherosclerosis Risk in Communities

Body iron status has been implicated in atherosclerotic cardiovascular disease. The main hypothesis was that high iron status was associated with increased oxidation of LDL. The associations of serum ferritin (a marker of iron status) and dietary iron intake with the susceptibility of LDL to in vitro oxidation (lag phase) and autoantibodies against MDA-modified LDL (two markers of oxidation stress) were examined among 281 men and 192 women with a mean age of 59 years (S.D. = 5) who participated in the Atherosclerosis Risk in Communities (ARIC) Study visit 2 in 1990 through 1992. Lag phase duration and the autoantibodies against MDA-modified LDL were weakly correlated with each other (r = 0.19, P = 0.001 in men; r = 0.15, P = 0.03 in women). In linear regression analysis adjusting for age, field center, blood storage time, and carotid atherosclerosis case-control status, there was no association between ferritin level and the lag-phase, or between ferritin level and autoantibodies against MDA-modified LDL in either sex. Further adjustment for traditional cardiovascular risk factors (smoking, vitamin supplement use, body mass index, LDL cholesterol, hypertension and diabetes) did not alter these null results. Ferritin was significantly and positively correlated with body mass index in both sexes (r = 0.21 among men and r = 0.22 among women) and with the waist-to-hip ratio among women (r = 0.26). In addition, among women, ferritin was positively correlated with orosomucoid (r = 0.24) and with sialic acid (r = 0.19). Dietary iron was not associated with the parameters of LDL oxidation or with ferritin level. These findings do not support a role of body iron stores in promoting oxidation of LDL.

Autoantibodies to gangliosides in sera of atherosclerotic patients

Using ELISA we studied the levels and clinical correlation of serum antibodies against gangliosides and 5-hydroxytryptamine (5-HT) in patients with atherosclerosis and clinical manifestations of cardiovascular disease. A range of 70-80% of the patients showed higher titers of anti-GM3(L) and anti-5HT as compared to normal serum. The anti-GM3(L) antibodies appeared to be directed mainly against GM3 present in platelets and were much less reactive against GM3 isolated from the aorta. We concluded that the antigens responsible for the elevated anti-GM3(L) and anti 5-HT levels in atherosclerotic sera are released by vessel-wall activated platelets. These results provide further evidence of on-going autoimmune processes in atherosclerosis. The content of total sialic (TS) and lipid-bound sialic acid (LBS) was measured in sera of patients with IHD and of similar numbers of healthy donors. In the patient groups the average TS and LBS concentration was about 25% higher than in the control group. These changes appeared to be associated with higher degrees of protein sialylation and larger amounts of LDL in the patient sera than in those of healthy controls.

Plasma sialic acid as a marker of the effect of the treatment on metastatic colorectal cancer

The concentration of total sialic acid (TSA) is increased in the plasma of patients with many types of cancer. The purpose of this study was to assess the usefulness of the TSA marker in predicting the efficacy of the treatment, and to compare TSA with two common markers, carcinoembryonic antigen (CEA) and the carbohydrate antigen 19-9 (CA 19-9). The study was performed on 44 patients treated for advanced colorectal carcinoma by a weekly 8 h continuous infusion of 5-fluorouracil (1300 mg/m2) plus bolus injection of L-folinic acid (100 mg/m2). TSA, CEA and CA 19-9 levels were measured before and after 3 months of treatment and their variations analysed as a function of the response to the treatment. TSA levels of patients with metastatic colorectal carcinoma before treatment (959 +/- 265 mg/l) were significantly higher than those of 32 healthy people (584 +/- 99 mg/l). The percentage of patients with TSA concentration above the cut-off level (782 mg/l) was 73% before treatment and 23% after. All patients who experienced an objective response to the treatment (complete, partial or minor response) (n = 29) had a significant decrease of TSA levels (t = 5.96; P < 0.001). When the disease was considered as stabilised (n = 10), TSA changed slightly, but it increased with progressive disease (4 out of 5 patients). Changes in CEA and CA 19-9 did not correlate as well as TSA to the treatment efficacy. Initial levels of TSA did not permit prediction of the efficacy of the treatment since they were not significantly different between the five response groups. TSA seems to be more likely involved in tumour changes than in tumour volume. Its determination could provide useful information about the spreading and metastatic properties of the tumour. TSA normalisation is an indicator of probable tumour growth arrest and its elevation could be a marker of relapse.

Relationship between immunoinflammatory proteins containing sialic acid and low-density lipoprotein serum concentrations

The aim of this study was to investigate the relationship between sialoglycoproteins and the lipoprotein profile in a group of children with different levels of low-density lipoprotein cholesterol. We have studied 177 children of 132 families who were sent to our Pediatric Lipid Research Clinic because of serum cholesterol concentrations higher than 5.17 mmol/l. At the time of diagnosis, we analyzed the serum lipoprotein profile and the sialoglycoproteins: alpha 1-antitrypsin, acid alpha 1-glycoprotein, haptoglobin, alpha 2-macroglobulin, transferrin, IgA, IgG, IgM, complement C3 component and ceruloplasmin. At 7.0 to 10.9 years, alpha 1-glycoprotein serum concentrations were higher in the high risk group than in the moderate risk group (P < 0.05). At 2.0 to 6.9 years, IgA and IgM serum concentrations were higher in the moderate risk group than in the low risk group (P < 0.05 and P < 0.01, respectively), and IgG and IgM serum concentrations were also higher in the high risk group than in the low risk group (P < 0.05). Our results seems to reflect a general reaction to injury or inflammation which could be associated with the atherosclerotic process.

Evidence for a correlation between ambient cholesterol levels and soluble plasma sialyltransferase enzyme activity

While soluble forms of the sialyltransferase (sialyl-T) enzyme have been detected in significant quantities in serum, the exact source(s) of the enzyme, or the factors controlling its secretion are poorly understood. In this study, we have examined the relationship between ambient plasma cholesterol concentrations and sialyl-T-activities and also levels of constituent plasma sialoglycoproteins (SGP). There was an inverse relationship between levels of the alpha 2, 6 sialyl-T enzyme and both total plasma cholesterol and HDL, although no such relationship was observed for the alpha 2,3 enzyme. While there was no correlation between total cholesterol and the levels of plasma SGPs, there was an inverse relationship between the HDL component and alpha 2,3 SGPs.