Biomarker profiles in serum and saliva of experimental Sj?gren's syndrome: associations with specific autoimmune manifestations

Introduction  

Sj?gren's syndrome (SS) is a systemic autoimmune disease that mainly targets the exocrine glands. The aim of this study was to investigate the involvement of 87 proteins measured in serum and 75 proteins analyzed in saliva in spontaneous experimental SS. In addition, we intended to compute a model of the immunological situation representing the overt disease stage of SS.     

Cloning and characterization of the CYS3 (CYI1) gene of Saccharomyces cerevisiae.

A DNA fragment containing the Saccharomyces cerevisiae CYS3 (CYI1) gene was cloned. The clone had a single open reading frame of 1,182 bp (394 amino acid residues). By comparison of the deduced amino acid sequence with the N-terminal amino acid sequence of cystathionine gamma-lyase, CYS3 (CYI1) was concluded to be the structural gene for this enzyme. In addition, the deduced sequence showed homology with the following enzymes: rat cystathionine gamma-lyase (41%), Escherichia coli cystathionine gamma-synthase (36%), and cystathionine beta-lyase (25%). The N-terminal half of it was homologous (39%) with the N-terminal half of S. cerevisiae O-acetylserine and O-acetylhomoserine sulfhydrylase. The cloned CYS3 (CYI1) gene marginally complemented the E. coli metB mutation (cystathionine gamma-synthase deficiency) and conferred cystathionine gamma-synthase activity as well as cystathionine gamma-lyase activity to E. coli; cystathionine gamma-synthase activity was detected when O-succinylhomoserine but not O-acetylhomoserine was used as substrate. We therefore conclude that S. cerevisiae cystathionine gamma-lyase and E. coli cystathionine gamma-synthase are homologous in both structure and in vitro function and propose that their different in vivo functions are due to the unavailability of O-succinylhomoserine in S. cerevisiae and the scarceness of cystathionine in E. coli.     

Gelation of xanthan with trivalent metal ions

In-situ gelation of semidilute xanthan solutions with trivalent chromium, aluminum or iron ions was studied by rheology and UV-spectroscopy. Measurements of the elastic modulus of xanthan gel cylinders prepared by dialysis against the complexing ion at pH values from 2 to 6 indicate that monomeric species of the ion are ineffective, whereas dimeric or higher oligomeric species are effective in crosslinking the polysaccharide. When chromium was used as the crosslinking species, the dependence of the gelation rate on the ionic concentration followed a power law with a coefficient of 1·7. The gelation time and the gelation rate were found to extrapolate to zero at 1 m Cr for 2·5 mg/ml xanthan. The limiting concentration of xanthan needed for gelation with 5 m Cr(III) at 20°C was estimated as 0·35 mg/ml. This critical xanthan concentration is close to the overlap concentration c^* estimated from the experimentally determined intrinsic viscosity [η] using c^* = 1·4/[η]. An apparent activation energy for crosslinking of xanthan was calculated as E_a = 42 kJ/mol and E_a = 108 kJ/mol for Cr and Al ions, respectively. The fractal dimensionality of xanthan-Cr at the sol-gel transition was estimated as 1·3 applying the Chambon-Winter criterion for gelation, thus indicating that this gelation criterion is applicable also to stiff-chain polysaccharides such as xanthan.     

Nucleotide sequences of the sfuA, sfuB, and sfuC genes of Serratia marcescens suggest a periplasmic-binding-protein-dependent iron transport mechanism.

The cloned sfu region of the Serratia marcescens chromosome confers the ability to grow on iron-limited media to an Escherichia coli K-12 strain that is unable to synthesize a siderophore. This DNA fragment was sequenced and found to contain three genes termed sfuA, sfuB, and sfuC, arranged and transcribed in that order. The sfuA gene encoded a periplasmic polypeptide with calculated molecular weights of 36,154 for the precursor and 33,490 for the mature protein. The sfuB gene product was a very hydrophobic protein with a molecular weight of 56,589. The sfuC gene was found to encode a rather polar but membrane-bound protein with a molecular weight of 36,671 which exhibited strong homology to consensus sequences of nucleotide-binding proteins. The number, structural characteristics, and locations of the SfuABC proteins were typical of a periplasmic-binding-protein-dependent transport mechanism. How Fe3+ is solubilized and taken up across the outer membrane remains an enigma.     

Improved methods for the formation and stabilization of R-loops

Improved methods for the formation and stabilization of R-loops for visualization in the electron microscope are presented. The two complementary strands of a duplex DNA are photochemically crosslinked once every 1 to 3 kb using 4, 5', 8 trimethylpsoralen. R-loops are then formed by incubation with RNA in 70% formamide at a temperature above the DNA melting temperature. Finally, the R-loops are stabilized by modifying the free single strand of DNA with glyoxal, thus minimizing the displacement of the hybridized RNA by branch migration. In this manner R-loops can be formed and visualized at a high frequency irrespective of the base composition of the nucleic acid of interest.     

Compensation of large motion sensor displacements during long recordings of limb movements

In motion capture applications using electromagnetic tracking systems the process of anatomical calibration associates the technical frames of sensors attached to the skin with the human anatomy. Joint centers and axes are determined relative to these frames. A change of orientation of the sensor relative to the skin renders this calibration faulty. This sensitivity regarding sensor displacement can turn out to be a serious problem with movement recordings of several minutes duration. We propose the “dislocation distance” as a novel method to quantify sensor displacement and to detect gradual and sudden changes of sensor orientation. Furthermore a method to define a so called fixed technical frame is proposed as a robust reference frame which can adapt to a new sensor orientation on the skin. The proposed methods are applied to quantify the effects of sensor displacement of 120 upper and lower limb movement recordings of newborns revealing the need for a method to compensate for sensor displacement. The reliability of the fixed technical frame is quantified and it is shown that trend and dispersion of the dislocation distance can be significantly reduced. A working example illustrates the consequences of sensor displacement on derived angle time series and how they are avoided using the fixed technical frame.