The likelihood of persistent arthritis increases with the level of anti-citrullinated peptide antibody and immunoglobulin M rheumatoid factor: a longitudinal study of 376 patients with very early undifferentiated arthritis

Introduction  

We wanted to assess the importance of the levels of anti-citrullinated peptide antibody (anti-CCP) and immunoglobulin M (IgM) rheumatoid factor (RF) in predicting development of persistent arthritis from undifferentiated arthritis (UA), and to investigate whether there is an added predictive value for persistent arthritis in testing for both anti-CCP and IgM RF.     

The identification of sulphatides in human erythrocyte membrane and their relation to sodium-potassium dependent adenosine triphosphatase.

Sulphatides (ceramide galactose-3-sulphate) were isolated from human erythrocyte membranes. The amount obtained was 3.3 mg from 6.7 kg of wet cells, or 1.5 X 10(-9) mol per g dry cells. The polar part was shown to be galactose-3-sulphate by chromatographic analysis, infrared spectrometry, and mass spectrometry after solvolytic desulphation. The ceramide part consisted of three major molecular species, sphingosine-palmitic acid, sphingosine-2-hydroxypalmitic acid, and phytosphingosine-2-hydroxypalmitic acid, as shown by thin-layer chromatography, mass spectrometry of galactosylceramides after desulphation, and gas chromatography of components after hydrolysis. The composition differed from other human erythrocyte sphingolipids. Although the amount of sulphatides is very low for erythrocyte, the ratio of sulphatide concentration and Na+-K+-ATPase activity [EC 3.6.1.3] is similar to the situation found for several animal tissues with an increased level of Na+ transport. This finding is discussed in relation to a recent model of sulphatide function in a transport unit for Na+ and K+ (cofactor site model).     

Albumin stabilizes 14,15-leukotriene A4

14,15-Leukotriene A4 is a pivotal biosynthetic intermediate in 15-lipoxygenase initiated leukotriene biosynthesis. This compound hydrolyzes instantaneously in phosphate buffer at pH 7.4. However, addition of human or bovine albumin to otherwise identical buffer solutions increases its stability. Intact 14,15-leukotriene A4 then decomposes by first-order kinetics with rate constants inversely proportional to the albumin concentration. Stabilization of 14,15-leukotriene A4 under certain conditions may influence its proportionate transformation by enzymatic vs non-enzymatic processes.     

Proton nuclear magnetic resonance analysis of anomeric structure of glycosphingolipids. The globo-series (one to five sugars).

Proton nuclear magnetic resonance spectroscopy has been reevaluated concerning the assignment of anomeric structure of glycosphingolipids. Solubility problems due to a varying number of sugars are avoided by permethylation, allowing a wide range of glycolipids to be compared. High resolution spectra were recorded in chloroform solution for the following substances with known structure, most of them representing a successive building up of members of the globo-series: ceramide, Galβ1 → 1Cer, a mixture of Glcα1 → 1Cer and Glcβ1 → 1Cer, lactosylceramide, globotriaosylceramide, globotetraosylceramide (globoside), and GalNAcα1 → 3globotetraosylceramide (Forssman hapten). Resonances originating in anomeric protons were identified and possible interference from other signals was defined. A complex set of resonances from H-1 of hexosamines was probably due to two separate conformers of the acetamido group caused by N-methylation. The complexity disappeared upon reduction with LiAlH₄. The chemical shifts and coupling constants were characteristic for the configuration of the glycosidic bond, the type of monomer, and in part for its location in the chain. At present, spectra may be recorded from 200-μg samples. It is concluded that the good quality and resolution obtained make this technique an alternative method to the presently used enzymatic degradation for establishing anomeric structure of glycosphingolipids.