Search results for "Neuraminic acid"
showing 10 items of 17 documents
Substantial deficiency of free sialic acid in muscles of patients with GNE myopathy and in a mouse model
2017
GNE myopathy (GNEM), also known as hereditary inclusion body myopathy (HIBM), is a late- onset, progressive myopathy caused by mutations in the GNE gene encoding the enzyme responsible for the first regulated step in the biosynthesis of sialic acid (SA). The disease is characterized by distal muscle weakness in both the lower and upper extremities, with the quadriceps muscle relatively spared until the late stages of disease. To explore the role of SA synthesis in the disease, we conducted a comprehensive and systematic analysis of both free and total SA levels in a large cohort of GNEM patients and a mouse model. A sensitive LC/MS/MS assay was developed to quantify SA in serum and muscle h…
Glycoprotein and ganglioside changes in human trophoblasts after exposure to pulsed doppler ultrasound
1995
Changes in glycoprotein and ganglioside composition in human trophoblasts (eighth week of gestation) after in vitro exposure to pulsed Doppler ultrasound (pulse duration 1.22 microseconds; repetition frequency 11.1 kHz; center frequency 4 MHz; ISPPA = 175.5 W/cm2; ISPTA = 0.59 W/cm2) were investigated. Evacuated trophoblasts were divided in two halves and insonated for 10 min on top of a 6-cm layer of 5% gelatin in 50-mL tubes (Falcon) at 37 degrees C. One half of each trophoblast was sham insonated and served as an internal control. After insonation trophoblasts were maintained at 37 degrees C for 24 h. Glycoproteins were detected using alpha-D-mannose specific lectins from Galanthus nival…
Evaluation of Sialic Acid in Infant Feeding: Contents and Bioavailability
2016
Sialic acid (Sia) contents and bioaccessibility (BA) in human milk (HM) and infant formulas (IFs) were determined, and Sia intakes by infants between 0 and 6 months of age were evaluated. Total Sia contents in HM decreased during lactation from 136.14 to 24.47 mg/100 mL. The total Sia contents in IFs (13.15-25.78 mg/100 mL) were lower than in HM and were not related to the addition of ingredients acting as sources of Sia in their formulation. The Sia intakes derived from IF consumption were lower than in HM, and only one IF reached the intakes provided by HM from the age of 2 months. Despite the lower total Sia content in IFs, the BA of Sia in IFs (88.08-92.96%) was significantly greater th…
Ranking the impact of human health disorders on gut metabolism: Systemic lupus erythematosus and obesity as study cases
2015
Multiple factors have been shown to alter intestinal microbial diversity. It remains to be seen, however, how multiple collective pressures impact the activity in the gut environment and which, if any, is positioned as a dominant driving factor determining the final metabolic outcomes. Here, we describe the results of a metabolome-wide scan of gut microbiota in 18 subjects with systemic lupus erythematosus (SLE) and 17 healthy control subjects and demonstrate a statistically significant difference (p < 0.05) between the two groups. Healthy controls could be categorized (p < 0.05) based on their body mass index (BMI), whereas individuals with SLE could not. We discuss the prevalence of SLE c…
The Allyl Ester as Carboxy-Protecting Group in the Stereoselective Construction of Neuraminic-Acid Glycosides
1988
The application of the allyl-ester moiety as protecting principle for the carboxy group of N-acetylneuraminic acid is described. Peracetylated allyl neuraminate 2 is synthesized by reacting the caesium salt of the acid 1 with allyl bromide. Treatment of 2 with HCl in AcCl or with HF/pyridine gives the corresponding 2-chloro or 2-fluoro derivatives 3 and 4, respectively (Scheme 1). In the presence of Ag2CO3, the 2-chloro carbohydrate 3 reacts with di-O-isopropylidene-protected galactose 5 to give the 2–6 linked disaccharide with the α-D-anomer 6a predominating (α-D/β-D = 6:1; Scheme 2). Upon activation of the 2-fluoro derivative 4 with BF3 · Et2O, the β-D-anomer 6b is formed preferentially (…
The apolipoprotein(a) moiety of lipoprotein(a) interacts with the complement activation fragment iC3b but does not functionally affect C3 activation …
1992
A previous study has shown that complement component C3 binds to recombinant apolipoprotein(a) (r-apo(a)). In the present report we have investigated the interactions between lipoprotein(a) (Lp(a)), r-apo(a) and C3 in relation to complement activation and degradation. Neither Lp(a) nor r-apo(a) affected complement activation as indicated by sheep and rabbit red blood cell hemolytic assays, and by assessment of the amount of C3a generated in zymosan-activated human serum in the presence or absence of Lp(a). Crossed immunoelectrophoretic analyses indicated that Lp(a) retarded the migration of iC3b in complement-activated serum but had no effects on C3, C3b, C3c or C3dg. Recombinant apo(a) exh…
Effect of simulated gastrointestinal digestion on sialic acid and gangliosides present in human milk and infant formulas.
2011
The effects of simulated gastrointestinal digestion upon sialic acid and gangliosides in infant and follow-on formulas and human milk, as well as their bioaccessibility, have been evaluated. The gastric stage is the step that causes a greater decrease in sialic acid and ganglioside contents. The intestinal stage only decreases the total and individual contents of gangliosides. After gastrointestinal digestion, neither sialic acid nor gangliosides were found in the nonbioaccessible fraction. The highest bioaccessibility (100 × content in soluble fraction after gastrointestinal digestion/total content) of sialic acid is found in human milk (87%), followed by infant formula (77%) and follow-on…
Gangliosides and sialic acid effects upon newborn pathogenic bacteria adhesion: An in vitro study
2012
The effect of the main gangliosides (GM(1), GM(3), GD(3)) and free sialic acid (Neu5Ac) upon the adhesion of pathogenic bacteria implicated in infant diarrhoea is assessed in vitro using the Caco-2 cell line. Concentrations of the bioactive compounds found in the bioaccessible (soluble) fraction of infant formula and human milk are employed. Bacterial adhesion behaviour included enterotoxigenic Escherichia coli (ETEC), enteropathogenic E.coli (EPEC), Listeria monocytogenes, Salmonella entericaserovartyphi, Shigella sonnei, Campylobacter jejuni and Helicobacter pylori. Three different approaches were assayed: pre-incubation of bacteria and compounds before addition to cells (competition); pr…
Determination of sialic acid and gangliosides in biological samples and dairy products: A review
2009
Gangliosides are sphingolipids containing one or more moieties of sialic acid in their structure. Both gangliosides and sialic acid are bioactive compounds related to animal physiology. Due to their biological relevance, analytical methods adapted to each type of matrix have been developed over time. The present study reviews the main methods applied to the analysis of sialic acid and gangliosides in biological samples and dairy products.
A new neuraminic acid derivative and three types of glycopeptides isolated from the Cuvierian tubules of the sea cucumber Holothuria forskali
1973
The Cuvierian tubules of Holothuria forskali Della Chiaje, a sea cucumber found in the Adriatic Sea, were investigated with regard to their carbohydrate moieties. From a Pronase digest of these tubules three types of carbohydrate units were isolated and characterized. 1. A high-molecular-weight glycopeptide fraction was shown to contain sulphated polyfucose, galactosamine, a uronic acid and a previously unknown neuraminic acid derivative. The sulphate was shown by i.r. analysis to be present as an O-ester. The carbohydrate unit was linked O-glycosidically to threonine and serine residues in the polypeptide chain. The hitherto unknown neuraminic acid derivative (Hf-neuraminic acid) was resis…