1,721,030 research outputs found
Detection of autoantibodies against actin filaments in celiac disease
No full textIntroduction: Serum autoantibodies specifically directed toward intracellular cytoskeletal actin filaments (anti-actin antibodies, AAA) were found to be associated with intestinal villous atrophy (IVA) in celiac disease (CD). The aim of this study was to assess IgA-AAA with a commercial test that uses sections of rat intestinal epithelial cells in a well-selected cohort of patients and to evaluate the relationship between the presence of serum IgA-AAA and the severity of intestinal mucosa damage. Materials and Methods: Serum samples from 70 CD patients and 150 controls subjects were analyzed retrospectively for the presence of IgA-AAA. Results: The indirect immunofluorescence test that we used has a specificity of 100%; the sensitivity of the test is not high (25.7%). In this study we also show that serum AAA are more frequently positive in CD patients with total IVA (77.8%) and that this association is significant Discussion: IgA-AAA certainly cannot take the place of much more sensitive tests such as a-tTG and EMA in the diagnosis of CD because of their low sensitivity; nonetheless, these antibodies could be determined in a-tTG and/or EMA positive patients who cannot undergo an intestinal biopsy because of a severe contraindication, or in the case of negative consensus regarding endoscopy, or when the histology interpretation is difficult. Conclusion: In conclusion, the IFI commercial test with intestinal epithelial cells as substrate offers a useful method for IgA-AAA determination. Serum IgA-AAA positivity is indicative of more severe intestinal histology damage and their assay could be a real help to the clinician, especially in the complicated cases. © 2012 Wiley Periodicals, Inc
Purine nucleotide catabolism in rat liver. Certain preliminary aspects of uricase reaction
No full textWe investigated the mechanism of action of uricase, which oxidizes uric acid to allantoin, in the rat. Allantoin may decompose chemically to urea and hydantoin, containing the carbons in positions 2 and 8 of the purine ring, respectively. These carbons are derived by formylation, catalyzed by formyltransferase, in two reactions of de novo synthesis. Since uric acid and allantoin are represented in equivalent amounts in the liver, we expected to find identical incorporation of radioactivity in C(2) and C(8) of both compounds after administration of (14)C-formate. In the case of (14)C-allantoin, this was true, but not for (14)C-uric acid extracted from rat liver. We interpret these results through a series of experiments and consideration
Identification and structural characterization of a transient Radical Species in the Uricase Reaction Mechanism
No full textUricase catalyzes the oxidation of urate to form allantoin, carbon dioxide and hydrogen peroxide. In this article, we demonstrate for the first time the presence of a radical intermediate involved in the reaction mechanism. Such radical species was entrapped using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide as spin trap and the relative adduct was detected by electron paramagnetic resonance (EPR) technique. A structure of such radical (5-hydroperoxy isourate) is proposed, through chemical results and density functional theory calculations of the EPR coupling constants
The Regulation of Alanine and Aspartate Aminotransferase by different aminothiols and by Vitamin B6 Derivatives
No full textWe examined the effects on alanine aminotransferase and aspartate aminotransferase of different aminothiols (L-cysteine, D-cysteine, cysteamine, L-cysteine ethyl ester, L-cysteine methyl ester) and several vitamin B-6 derivatives (pyridoxal, pyridoxamine, pyridoxol, pyridoxol 5'-phosphate), before and after treatment with KOCN, which transforms these molecules into the corresponding carbamoyl derivatives. Only GPT, and not GOT, was specifically inhibited by L-cysteine and, to a lesser extent, by D-cysteine. The association reaction: PLP + apo GPTholo GPT was inhibited by the vitamin B-6 derivatives, and this inhibition was prevented by pretreatment of the vitamin B-6 derivatives with KOCN. All the observed effects occurred at pH 7, 37 degrees C, at mM and even lower concentrations of reagents. Hence, they all potentially play a physiological role, in the regulation of the PLP dependent enzymes and of the vitamin B-6 levels in the cell
High-performance liquid chromatography of thiazolidinic compounds obtained by condensation of pyridoxal 5'-phosphate or pyridoxal with aminothiols (L- or D-cysteine, cysteamine, L-cysteine ethyl ester)
No full textWe investigated six thiazolidine 4-carboxylic acids of biological interest, obtained by condensation of pyridoxal 5'-phosphate or pyridoxal with L- or D-cysteine, cysteamine or L-cysteine ethyl ester. A reversed-phase high-performance liquid chromatographic method, using a C18 column for their separation, was developed by sequential optimization of the pH and the gradient of the mobile phase. Resolution of the compounds was obtained with an analysis time of less than 20 min
Carbamoylation of B6 Vitamins
No full textThe reaction of B6 vitamins 1–3 with cyanate, in the presence of equivalent amounts of hydrochloric acid, yields different adducts according to the structure of the starting material. Regiospecific attack on the amino group or the phenolic hydroxy group was found for 2a,b and 3a,b, respectively. From the aldehydes 1a,b, the 2H‐pyrido[3,4‐e]‐1,3‐oxazin‐2‐ones 7a,b were obtained through an attack on both the phenolic and aldehyde group. Copyright © 1991 Journal of Heterocyclic Chemistry
High-performance liquid chromatography of two derivatives of vitamin B6, the carbamoyl derivatives of pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate
No full textWe present the results of a study of the high-performance liquid chromatography of two vitamin B6 derivatives: the carbamoyl derivatives of pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate. These compounds, obtained by condensation of either pyridoxal 5'-phosphate or pyridoxamine 5'-phosphate with either carbamoyl phosphate or potassium cyanate, were separated on an octadecyl silica column with a mobile phase consisting of 0.01 M potassium phosphate (pH 5.0)-methanol (98:2); detection was at 254 nm. The method was sensitive, fast and precise
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