Novel Protein Glycan-Derived Markers of Systemic Inflammation and C-Reactive Protein in Relation to Glycemia, Insulin Resistance, and Insulin Secretion.

OBJECTIVE: N-acetylglucosamine/galactosamine (GlycA) and sialic acid (GlycB) moieties of glycosylated serum proteins are nonspecific measures of inflammation, but conclusive data on their relationship with insulin resistance or insulin secretion are missing. Therefore, we aimed to examine the relation of GlycA, GlycB, and C-reactive protein (CRP) to direct measures of insulin sensitivity (insulin sensitivity index [SI]) and insulin secretion (acute insulin response [AIR]). RESEARCH DESIGN AND METHODS: This study used cross-sectional analyses and included 1,225 participants with and without type 2 diabetes in the Insulin Resistance Atherosclerosis Study (IRAS). SI and AIR were measured using the frequently sampled intravenous glucose tolerance test, and GlycA and GlycB were measured using nuclear magnetic resonance spectroscopy. RESULTS: GlycA and GlycB had a strong correlation with CRP (r = 0.60 [P < 0.001] and r = 0.46 [P < 0.001], respectively). In a linear regression model with both GlycA and CRP as independent variables, GlycA (ß × 1 SD, -0.04 ± 0.02; P < 0.01) and CRP (-0.06 ± 0.02; P < 0.001) were independently associated with SI even after adjusting for demographics, smoking, physical activity, plasma glucose, and BMI. However, neither CRP nor GlycA had an independent relationship with AIR. CONCLUSIONS: GlycA may complement CRP in evaluating the relationship between inflammation, glucose tolerance, and insulin resistance.

Towards a full integration of optimization and validation phases: An analytical-quality-by-design approach.

When using an analytical method, defining an analytical target profile (ATP) focused on quantitative performance represents a key input, and this will drive the method development process. In this context, two case studies were selected in order to demonstrate the potential of a quality-by-design (QbD) strategy when applied to two specific phases of the method lifecycle: the pre-validation study and the validation step. The first case study focused on the improvement of a liquid chromatography (LC) coupled to mass spectrometry (MS) stability-indicating method by the means of the QbD concept. The design of experiments (DoE) conducted during the optimization step (i.e. determination of the qualitative design space (DS)) was performed a posteriori. Additional experiments were performed in order to simultaneously conduct the pre-validation study to assist in defining the DoE to be conducted during the formal validation step. This predicted protocol was compared to the one used during the formal validation. A second case study based on the LC/MS-MS determination of glucosamine and galactosamine in human plasma was considered in order to illustrate an innovative strategy allowing the QbD methodology to be incorporated during the validation phase. An operational space, defined by the qualitative DS, was considered during the validation process rather than a specific set of working conditions as conventionally performed. Results of all the validation parameters conventionally studied were compared to those obtained with this innovative approach for glucosamine and galactosamine. Using this strategy, qualitative and quantitative information were obtained. Consequently, an analyst using this approach would be able to select with great confidence several working conditions within the operational space rather than a given condition for the routine use of the method. This innovative strategy combines both a learning process and a thorough assessment of the risk involved.

Elevated plasma glycosaminoglycans in chickens with tibial dyschondroplasia induced by a Fusarium oxysporum isolate.

Chicken plasma glycosaminoglycans (GAGs) were isolated and digested. Their building block molecules, namely, glucosamine and galactosamine, were quantified by gas chromatography. The levels of these two amino sugars were elevated in broiler chickens with tibial dyschondroplasia (TD) induced by culture material of Fusarium oxysporum (FO), a mold isolated from corn originated from the endemic region of Kaschin-Beck disease (KBD) in China. As the TD severity score changed from 1 (healthy) to 2, 3, and 4, glucosamine increased by 10%, 33%, and 57% and galactosamine by 9%, 13% and 48%, respectively. The elevated plasma GAGs correlated to TD severity but not to the amount of FO material in the diets. This correlation of plasma GAGs to TD in chickens parallels the reported correlation of urinary GAGs to KBD in humans. The possibility of TD as an animal model for KBD is discussed.

Plasma glucosamine and galactosamine in ischemic heart disease.

Because of the importance of glycosaminoglycans and glycoproteins in the pathogenesis of atherosclerosis, the hexosamine concentrations of plasma were determined in 28 male survivors of acute myocardial infarction and in 50 healthy males aged 30-60 years. Glucosamine and galactosamine were determined by ion-exchange chromatography of hydrolyzed whole plasma and hydrolyzed deproteinized plasma. Considerably higher plasma levels of non-protein-bound hexosamine (500 nmol/ml) and lower levels of protein-bound hexosamines (3770 nmol/ml) were observed in the ischemic heart disease group, compared with the plasma levels of non-protein-bound hexosamine (320 nmol/ml) and protein-bound hexosamine (4260 nmol/ml) of the control group. This difference is due to changes in glucosamine concentration. The galactosamine concentration is similar in the two groups. The ratio of non-protein-bound to protein-bound hexosamines in patients is about twice as high as the ratio found in controls. The glucosamine/galactosamine ratio of protein-free plasma is significantly higher in patients (12.1) than in controls (8.3). These changes in plasma hexosamines correlate with increased plasma homocysteine, cholesterol, and triglycerides observed in the patient group. The findings show that characteristic quantitative and qualitative changes in plasma hexosamine levels accompany atherosclerosis. Determination of these substances may be helpful in diagnosis and management of patients with atherosclerosis.

The carbohydrate composition of human serum amyloid P component.

The carbohydrate moiety of human serum amyloid P component was analyzed and found to consist of equal amounts of galactose and mannose (total 4.0%), of glucosamine and galactosamine in a ratio of 7:1 (total 2.7%) and sialic acid (3.9%). It should be noted that this is the first report on the separate quantification of the neutral hexoses and the demonstration of the presence of galactosamine. The contents of glucosamine and galactosamine suggest that this protein possesses both an N- and an O-glycan.

Erythrocyte glycosphingolipids of four siblings with the rare blood group p phenotype and their parents.

Erythrocytes that exhibit the rare blood group p phenotype lack the P antigen (globotetraosylceramide) and the Pk antigen (globotriaosylceramide). This phenotype is inherited as an autosomal recessive condition and the red cells of heterozygous individuals, parents and children of p persons, are serologically normal but no chemical analyses of their red cells have been reported. We have studied an unusual family in which all five children exhibit the p phenotype. In addition to the abnormalities described previously, the erythrocytes of four siblings had twice the normal concentration of lactotriaoslyceramide and lactoeotetraosylceramide. These cells also contained 3-5 times as much sialosyllactoneotetraosylceramide and up to a two-fold increase in Gm3 ganglioside. The glycolipids of the parents'erythrocytes were normal. Electrophoretic analysis of the glycoproteins of the proposita's erythrocytes revealed no abnormalities, but her erythrocyte membranes contained approximately 35% less galactosamine than normal red cells. This abnormality resulted from a marked decrease in galactosamine that was soluble in chloroformmethanol. The lipid-extracted residue, which contained the glycoproteins, had a normal galactosamine content.

Partial purification of a serum factor that causes necrosis of tumors.

Tumor necrosis can be induced in transplanted mouse methylcholanthrene-induced sarcoma by a tumor necrosis factor in the serum of mice infected with bacillus Calmette-Guérin and given bacterial endotoxin. Sera from normal mice, endotoxin-treated mice, and mice infected with bacillus Calmette-Guérin do not contain this factor. A 20- to 30-fold purification of the serum factor has been achieved by (NH4)2SO4 fractionation, Sephadex G-100 and G-200 gel filtration, and preparative polyacrylamide electrophoresis. Tumor necrosis factor is not bacterial endotoxin. It migrates with alpha-globulins, is made up of at least four subunits, and has a molecular weight of about 150,000. The active factor is a glycoprotein that contains sialic acid and galactosamine.

Glycopeptides of erythrocyte membranes in some hematological disorders.

Red cell membrane glycopeptides of subjects suffering from different hematological disorders (PNH, hemolytic anemias, dyserythropoietic anemias and polycythemia vera) have been characterized. In most cases, except in polycythemia vera, a decrease of sialic acid and galactosamine was detected. The role of these alterations is discussed with regard to the decrease of membrane glycopeptides during physiological aging of the red cell.