A comparative study of total protein, total and lipid associated serum sialic acid levels in patients with Behçet's disease and control groups

Sialic acid and incidence of hospitalization for diabetes and its complications during 40-years of follow-up in a large cohort: the Värmland survey

AIM

To examine the association of sialic acid (SA) with first recorded diabetes mellitus-related hospitalization.

METHODS

From a population-based study in Värmland, Sweden, between 1962 and 1965, 87,035 men and women were selected and followed for first recorded diabetes-related hospitalization until 2005. The association of SA was calculated and stratified for gender by Cox's proportional hazards models. Adjustments were made for conventional risk factors and socioeconomic status. Association analyses were made for comparisons between SA-levels above and below median.

RESULTS

The mean age was 47.2 (SD 13.0) years and the total numbers of incident diabetes-related hospitalizations in men and women were 3445 and 3273, respectively. Hazard ratios per one standard deviation of SA were 1.12 (95% CI: 1.08-1.17, p<0.0001) in men and 1.17 (95% CI: 1.13-1.22, p<0.0001) in women. Interaction analyses indicated a relatively higher SA-associated risk in women than in men with above median SA levels.

CONCLUSIONS

In this large population-based cohort followed for more than 40 years, elevated SA, as a marker of systemic inflammation, was independently associated with risk of diabetes and diabetes-related hospitalizations.

Significance of serum and urine neuraminidase activity and serum and urine level of sialic acid in diabetic nephropathy

BACKGROUND

Prospective studies have reported associations among various markers of inflammation and the incidence of diabetes, and it has been proposed that inflammation has a causal role in the development of diabetes. The objective of this study was to investigate the significance of serum and urine neuraminidase activity (NA) and serum and urine sialic acid (SA) level in patients with Diabetic nephropathy.

METHODS

In a prospective study, 190 diabetic patients with established diabetic nephropathy, 30 type 2 diabetes patients without any diabetic related nephropathy, and 36 non-diabetic patients with diagnosed nephropathy were enrolled. Two hundred and forty healthy individuals without diabetes or kidney disease were also enrolled as control group. Fasting venous blood samples and urine samples were collected and checked for serum and urine NA and SA level.

RESULTS

In the diabetic nephropathy group, the mean value of serum and urine NA was 64.6 ± 2.6 and 11.7 ± 1.2 mU/ml, respectively, and mean values of serum and urine SA were 93.2 ± 3.6 and 17.7 ± 1.4 mg/dl, respectively. Serum and urine NA and SA levels were significantly higher in patient with diabetic nephropathy when compared to the other groups (P < 0.001).

CONCLUSIONS

Our study suggests that there is a strong association between elevated serum and urine NA and serum and urine SA levels with the presence of diabetic nephropathy in type 2 diabetic patients. Further investigations are needed on the diagnostic and prognostic significance of these two inflammatory markers.

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.

Serum total sialic acid in cholangiocarcinoma patients: an ROC curve analysis

OBJECTIVES

This study was undertaken to establish the diagnostic utility of serum total sialic acid (TSA) for patients with cholangiocarcinoma (CCA).

DESIGN AND METHODS

Serum TSA was determined in 89 histologically confirmed CCA patients, 38 with benign hepatobiliary diseases (BHD) and 43 healthy persons. To check whether the test could adequately discriminate between these groups, complete statistical Receiver Operating Characteristic (ROC) curves were analyzed.

RESULTS

The mean value of serum TSA in CCA patients (2.75 +/- 0.67 mmol/L) was significantly higher than that in the BHD (2.33 +/- 0.69 mmol/L p < 0.002) and healthy persons (1.89 +/- 0.46 mmol/L p < 0.001) groups. The areas under the ROC curves were 0.6699 and 0.8558, respectively. A cut-off value of 2.33 mmol/L discriminated between the CCA, BHD and healthy groups with a sensitivity of 71.9% and a positive predictive value range of 80 to 89%.

CONCLUSION

Determination of TSA yielded high diagnostic values for differentiating between CCA, BHD and healthy persons. The determination of serum TSA would be most useful as an adjunct diagnosis rather than an early detection and screening tool because of the apparent nonspecificity of SA to a given disease.

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.

Elevated serum sialic acid in pregnancy

OBJECTIVE

Serum sialic acid has recently gained interest as a possible cardiovascular risk factor as well as a potential tumour marker. The effect of pregnancy on serum sialic acid is unclear particularly in the post-partum period.

DESIGN

Longitudinal cohort.

SETTING

Teaching hospital antenatal clinic.

POPULATION

29 pregnant women, 27 age matched non-pregnant women.

METHODS

Specific enzymatic assay for sialic acid. The first serum sample was taken between 37 and 42 weeks of gestation; in 22 women this was followed by a second serum sample at 12 weeks postpartum. Serum sialic acid concentration was also measured in the 27 controls.

RESULTS

Mean (SD) serum sialic acid concentration was higher during pregnancy than post-partum: 91.1 (11.1) v 77.5 (11.1) mg/dl (p < 0.001); or in the control group: 66.0 (9.7) mg/dl (p < 0.001).

CONCLUSIONS

Serum sialic acid is elevated during pregnancy and postpartum.