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Aims: The aim of this study was to investigate the changes associated with alcohol abuse in the structure and metabolism of lipoproteins, in particular, the content of sialic acid (SA)., Methods: The level of SA in apolipoprotein B (apoB)-containing lipoproteins was determined by using enzymatic assay followed by the precipitation step in 126 alcohol-dependent men., Results: Increased level and content of SA in apoB-containing lipoproteins was found not only in the hyperlipidemic alcoholic subjects but also in normolipidemic subjects. The highest value was observed in alcoholics with type IIb of hyperlipidemia followed by type IV, IIa and normolipidemia. The increase of SA level in apoB-containing lipoproteins in type IIb hyperlipidemia is accompanied by an increase of serum apoB concentration. Increased level and content of SA in apoB-containing lipoproteins did not correlate with any markers of alcohol abuse and lipid status., Conclusions: There are changes in the structure of atherogenic lipoproteins in alcoholics, which consist of increasing SA concentration in apoB-containing lipoproteins. These changes are independent of serum apoB level and may precede the development of hyperlipidemia.

Background: To determine whether the cellular inflammatory marker of activated macrophages and monocytes, neopterin (NEO), and the acute-phase inflammatory markers sialic acid (SA) and C-reactive protein (CRP) are elevated in pregnancy and further elevated in the pregnancy syndrome preeclampsia., Methods: Maternal plasma concentrations of NEO, SA, and CRP were measured by high-sensitivity enzyme-linked immunosorbent assay (ELISA) or high-performance liquid chromatography in 20 nonpregnant women, 40 women with uncomplicated pregnancies, 50 women with transient hypertension of pregnancy alone, 49 women with small for gestational age (SGA) infants without preeclampsia, and 47 women with preeclampsia., Results: The mean concentration of plasma NEO, SA, and CRP were all significantly elevated in all groups of pregnant women compared to nonpregnant women (P < 0.001 for all). In addition, maternal plasma NEO concentrations were further elevated in women with preeclampsia compared to the other groups of pregnant women (P < 0.01). As expected, the acute-phase inflammatory markers CRP and SA correlated positively with each other. However, CRP was also correlated with the activated macrophage and monocyte marker NEO in women with transient hypertension of pregnancy and with preeclampsia (P < 0.05)., Conclusions: The inflammatory markers NEO, SA, and CRP are all elevated during pregnancy. However, only NEO, a marker of macrophage and monocyte activation, was further elevated in women with preeclampsia. These data suggest that there is a striking increase in inflammation during pregnancy, and cellular immune activation is further elevated during preeclampsia.

Aims: Total sialic acid (TSA) has been suggested as a marker for chronic alcohol abuse. It seems that the elevation of TSA during excessive alcohol consumption reflects the changes in sialylated glycoproteins in the sera. On the other hand, chronic ethanol consumption increases the desialylation rate of many serum glycoproteins. The aim of this study was to evaluate the relationship between the total and free form of sialic acid levels (FSA), and the concentration of sialylated glycoproteins in alcoholics., Methods: We determined the serum concentration of many glycoproteins (alpha1-antitrypsin, alpha1-acid glycoprotein, haptoglobin, ceruloplasmin, transferrin, complement C3 protein, fibrinogen and immunoglobulin G) in a sample of 100 alcoholics and 30 healthy controls. Total sialic acid was determined by the enzymatic method and its free form by using a modification of the thiobarbituric acid method., Results: Among alcoholics, we found increased concentrations of alpha1-antitrypsin and alpha1-acid glycoprotein but decreased levels of transferrin. The concentrations of TSA and FSA were significantly higher in alcoholics than in healthy controls. The tested glycoproteins, except for transferrin and immunoglobulin G, positively correlated with TSA and FSA. The correlations with TSA were higher than that with FSA., Conclusions: Chronic alcohol abuse alters the concentrations of some sialylated glycoproteins in the sera. The alpha1-antitrypsin, alpha1-acid glycoprotein, and transferrin are the only affected glycoproteins. The serum level of total and free form of sialic acid in the sera of alcoholics depends on the concentration of the most sialylated glycoproteins.

Aims: Facial flushing caused by alcohol drinking is a typical symptom of high sensitivity to alcohol in orientals. We investigated whether drinking alcohol influences atherosclerotic risk factors in alcohol flushers and non-flushers in patients with diabetes mellitus., Methods: A cross-sectional study was performed using 225 subjects with type 2 diabetes. Sensitivity to alcohol was surveyed by a questionnaire on facial flushing. Subjects were divided into three groups by average amount of alcohol drinking (non-drinkers; light drinkers: <140 g/week; heavy drinkers: 140 g/week or more)., Results: Systolic blood pressure and blood HDL cholesterol were significantly higher in heavy drinkers than in non-drinkers. There were no significant differences in body mass index, blood pressure, blood total cholesterol, HDL cholesterol, uric acid, fibrinogen and sialic acid levels in flushers and non-flushers. In alcohol flushers, diastolic blood pressure and HDL cholesterol in heavy drinkers were significantly higher than those in non-drinkers, and systolic blood pressure was significantly higher in heavy drinkers than in non-drinkers and light drinkers. On the other hand, blood pressure and HDL cholesterol in non-flushers were not significantly different among non-, light and heavy drinkers. Serum total cholesterol was not significantly different among the three drinking groups both in flushers and non-flushers., Conclusions: Blood pressure and HDL cholesterol are more prone to be affected by drinking in flushers than in non-flushers, suggesting that alcohol sensitivity evaluated by flushing response due to drinking alcohol should be taken into account when the effects of alcohol drinking on atherosclerotic risk factors are considered in oriental patients with type 2 diabetes mellitus.

The release of Sialic acid (SA) into the serum by Trypanosoma congolense infected BalbC mice was investigated. A progressive increase in the level of serum SA corresponding to anemia and parasitemia was observed. At maximum parasitemia, the level of total SA from the red blood cells (RBC) dropped by about 45%. Solved polynomials revealed an association between free serum SA and RBC-SA. Positive roots of quadratics were used to predict complete cleavage of RBC-SA on day 7.01 and maximum accumulation of free serum SA on day 6.6. A steady rise in the level of serum sialidase (SD) activity and a low packed cell volume (PCV) with an increase in parasitemia were observed. Mice infused with galactose, methyl-beta-gal, lactose, mannose, or L-arabinose and challenged by intraperitoneal inoculation with Trypanosoma congolense neither developed anemia nor secreted free SA above the control level even though there was detectable SD activity. Bloodstream Trypanosoma congolense parasites were isolated using DEAE cellulose from heparinized blood of experimentally infected BalbC mice. The parasites were lysed with 0.2% Triton-CF 54 to release membrane bound SD. The activity of the SD was proportional to the number of parasites. The enzyme was partially purified on Q-Sepharose and Fetuin agarose columns successively. The final active fraction from the latter column was used as the partially purified SD. The enzyme had an optimum pH of 6 and was maximally active at 37 degrees C with a requirement for the divalent ions Ca(2+) and Mg(2+). The enzyme was highly specific for NeuAc5alpha2,3 lac and Methylumbelliferyl-Neu5Ac (4-MU-Neu5Ac) with K(M) values of 0.34 and 0.025 mM, respectively. It was inhibited competitively by 2,3-didehydroneuraminic acid (Neu5Ac2en) and para-nitro-phenyloxamic acid (pNPO) with inhibition binding constants K(i) of 65 and 215 micro M, respectively. In deviation from the procyclic trypanosomal SD, it lacked trans-sialidase (TS) activity. The possible role of a secreted bloodstream Trypanosoma congolense SD and the development of anemia in the pathogensesis of trypanosomiasis are discussed.

Background: Adhesion molecules have been implicated in tumor progression. In this study, we aimed to investigate serum soluble intercellular adhesion molecule-1 (sICAM-1) and total sialic acid (TSA) levels in laryngeal carcinoma and correlate their levels with the cancer stage., Method: The sera from 35 patients with laryngeal cancer (10 at stage II, 12 at stage III and 13 at stage IV) were extracted before treatment. The concentrations of sICAM-1 and TSA were measured by enzyme-linked immunoassay and the thiobarbituric acid method, respectively and compared with those from a healthy control group (n = 34)., Results: Mean serum sICAM-1 and TSA levels were found to be higher in the total patient group (the lowest level belonging to stage II) than in the control group (p < 0.001, control versus total patient group). As the stage of the disease increased, higher levels of sICAM-1 and TSA were determined. The correlations between TSA and sICAM-1 became more significant as the stage of the disease increased (r= 0.67, p < 0.05 in stage II, r= 0.86, p < 0.001 in stage III and r = 0.90, p < 0.001 in stage IV)., Conclusion: These data reveal that the significant correlations between sICAM-1 and TSA in laryngeal cancer, more prominent at advanced stage, might reflect the similar nature of these molecules, which function as adhesion molecules.

Background: The serum sialic acid (SA) concentration has been reported to be a potentially useful but nonspecific disease marker. We wanted to study which factors influence SA concentration in a well-characterized healthy population., Methods: SA was determined in 97 women and 96 men with a colorimetric Warren method., Results: The mean +/- SD concentrations of SA were 634 +/- 109 (95% confidence interval, 612-656) and 630 +/- 106 (95% confidence interval, 608-651) mg/L for women and men, respectively. The serum SA showed a significant positive association with body mass index and with systolic and diastolic blood pressure among both women and men. SA also correlated significantly with the use of contraceptive pills and age among women and with smoking among men., Conclusions: Our study suggests that SA does not increase with age in men but appears to increase with female menopause. The strong positive association with blood pressure may explain why SA predicts cardiovascular mortality.

The plasma level of sialic acid (NeuAc) in inherently scorbutic [Osteogenic Disorder Shionogi (ODS)] rats was increased by 21 days of vitamin C deficiency. The brain content of NeuAc was decreased by deficiencies of these vitamins. The NeuAc level in the liver was not affected significantly by these deficiencies.

Background: Total serum sialic acid is a recently investigated marker for cardiovascular mortality and carotid atherosclerosis. This study tested the hypothesis that past infection by Herpes simplex type 1 or type 2 viruses or Cytomegalovirus or Chlamydia pneumoniae accounts for the association between serum total sialic acid and atherosclerosis., Methods: Population-based samples of men and women living in four US communities were used in a cross-sectional study. Cases and matched controls were defined by B-mode ultrasound measurements of carotid and popliteal arterial wall thickness. In all, there were 267 case control pairs with information about antibody titres to viruses and 256 pairs with information about antibody titres to Chlamydia pneumoniae., Results: Serum total sialic acid (S-TSA) level was significantly higher in cases with carotid atherosclerosis compared to their controls. The odds ratio for carotid atherosclerosis associated with sialic acid level above 75th percentile was 1.73 (95% confidence interval [CI]: 1.02-2.95) in the sample with information about antibodies to viruses and 1.70 (95% CI: 1.00-2.93) in the sample with information about antibodies to C. pneumoniae. Adjustment for titres of antibodies to viruses and C. pneumoniae had no impact on the relation between sialic acid and carotid atherosclerosis., Conclusions: From these results, it seems unlikely that previous infection by any of these micro-organisms accounts for the relation between S-TSA level and carotid atherosclerosis.

Given the important role of apolipoprotein E (apoE) in triglyceride metabolism, we analyzed plasma levels and degree of sialylation of apoE in subjects with the acquired immunodeficiency syndrome (AIDS), a disorder accompanied by hypertriglyceridemia. Levels of apoE were significantly increased (1.84-fold) and correlated with plasma triglycerides (r = .663, P < .001) in AIDS. Subjects with AIDS and the apoE3/E2 phenotype showed the most prominent increases in both plasma triglyceride and apoE levels (3.4 and 2.2-fold over controls). Additionally, apoE from subjects with AIDS showed an increased amount of sialylation, compared with controls (34% increase in apoE3/E3 subjects). Increased sialylation correlated with the increase in apoE levels. In contrast, there was no increase in sialylation of apo C-III in AIDS. Thus, triglyceride levels in AIDS are influenced by apoE subtype and subjects with AIDS show changes in apoE structure.

Objective: The concentration of serum total sialic acid (S-TSA) is one recently investigated risk marker for cardiovascular mortality and atherosclerosis. Since the mortality from coronary heart disease is higher in the United States than in Japan, one could expect the S-TSA to be higher among Caucasian US citizens than among Japanese citizens, a hypothesis that is tested in this study., Design: Cross-sectional study of population-based samples of Japanese and US Caucasian men and women., Setting: The rural community Akita, Japan, and the suburbs of Minneapolis, Minnesota., Subjects: These were 75 consecutive men and women from Akita and Minneapolis respectively aged 47-69 years in 1990. People who had smoked cigarettes during the past 5 years; who had a history of diabetes mellitus, liver disease, coronary heart disease, or stroke; or who were taking anticoagulants were excluded., Outcome Measures: Serum total sialic acid levels in male and female Japanese and US Caucasian subjects with adjustment for age, systolic blood pressure, fibrinogen, triglycerides and in women also for menopausal status. Race and sex-specific correlations with serum total sialic acid for selected cardiovascular risk markers., Results: The entire sialic acid distributions were shifted to the right in Caucasian men and women compared to Japanese men and women. The mean +/- standard deviation concentrations of S-TSA were 54.1 +/- 5.3 mg/dl in Japanese men and 58.7 +/- 5.6 mg/dl in Caucasian men (P < 0.001). In women, the concentrations were 54.8 +/- 5.1 and 63.1 +/- 6.0 mg/dl respectively (P < 0.001). S-TSA level correlated significantly and positively with fibrinogen levels in Caucasian and Japanese men and women and with triglyceride levels in Caucasian and Japanese men and in Caucasian women but not in Japanese women. After adjustment for age, systolic blood pressure, fibrinogen, triglycerides and menopausal status, the sialic acid levels were 2.2 (P = 0.009) and 6.2 (P < 0.001) mg/dl higher in Caucasian compared to Japanese men and women respectively., Conclusions: Higher S-TSA levels in Caucasians living in Minneapolis compared to Japanese living in Akita, Japan is in concordance with the higher cardiovascular mortality in the US. Differences in S-TSA levels may reflect international differences in the prevalence of atherosclerosis.

Background: Previous studies have shown that the serum level of sialic acid is associated positively with mortality from coronary disease and stroke. In this study its relation with carotid atherosclerosis was evaluated., Methods: From the Atherosclerosis Risk in Communities (ARIC) Study, 323 cases with carotid intima-media wall thickness above the 90th percentile (measured with B-mode ultrasound) were matched 1:1 with controls without atherosclerosis. Serum sialic acid, plasma LDL and HDL cholesterol, serum insulin concentrations, blood pressure, antihypertensive medication use, and smoking status were used to assess the independent contribution of the sialic acid level to carotid atherosclerosis., Results: The mean (SD) serum sialic acid concentration was 75.0 (9.7) mg/dl in cases and 70.7 (8.9) mg/dl in controls (P = 0.0001). In a conditional logistic model with adjustment for age, LDL-cholesterol, HDL-cholesterol, serum insulin, smoking and hypertension, the odds ratio associated with sialic acid above the 75th percentile (> or = 78.3 mg/dl) versus below was 1.65 with a 95% confidence interval of 1.01-2.70., Conclusion: The sialic acid level is correlated with the presence of carotid atherosclerosis, independently of major cardiovascular disease risk factors. The biological mechanism behind this association is not resolved.