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  • 1
    Keywords: SPECTRA ; CELLS ; EXPRESSION ; CELL ; COMBINATION ; Germany ; human ; PERFUSION ; PROTEIN ; PROTEINS ; SEQUENCE ; SIGNAL ; cell culture ; culture ; ACID ; FORM ; ASSAY ; PURIFICATION ; GOLGI-APPARATUS ; CHROMATOGRAPHY ; HIGH-LEVEL EXPRESSION ; CORE PROTEIN ; serine ; QUANTITIES ; AFFINITY ; PROTEOGLYCAN ; AFFINITY-CHROMATOGRAPHY ; BETA-D-XYLOSYLTRANSFERASE ; glycosyltransferase,proteoglycan,perfusion chromatography,insect cells ; HIGH-LEVEL ; JAR CHORIOCARCINOMA CELLS ; MOLECULAR-CLONING ; PERFUSION CHROMATOGRAPHY ; PROTEIN LINKAGE REGION ; SERUM XYLOSYLTRANSFERASE ; SYSTEMIC-SCLEROSIS ; UDP-D-XYLOSE
    Abstract: Human xylosyltransferase I (XT-I) catalyzes the transfer of xylose from UDP-xylose to consensus serine residues of proteoglycan core proteins. Expression of a soluble form of recombinant histidine-tagged XT-I (rXT-I-HIS) was accomplished at a high level with High Five/pCG255-1 insect cells in suspension culture. The recombinant protein was purified to homogeneity by a combination of heparin affinity chromatography and metal (Ni2+) chelate affinity chromatography. Using the modern technique of perfusion chromatography, a rapid procedure for purification of the rXT-I-HIS from insect cell culture supernatant was developed. The purified, biologically active enzyme was homogeneous on SIDS-PAGE, was detected with anti-XT-I-antibodies, and had the expected tryptic fragment mass spectrum. N-terminal amino acid sequencing demonstrated that the N-terminal signal sequence of the expressed protein was quantitatively cleaved. The total yield of the enzyme after purification was 18% and resulted in a specific XT-I activity of 7.9 mU/mg. The K-m of the enzyme for recombinant [Val(36) Val(38)](delta1),[Gly(92),Ile(94)](delta2) bikunin was 0.8 muM. About 5 rag purified enzyme could be obtained from 1 L cell culture supernatant. The availability of substantial quantities of active, homogeneous enzyme will be of help in future biochemical and biophysical characterization of XT-I and for the development of a immunological XT-I assay. (C) 2003 Elsevier Inc. All rights reserved
    Type of Publication: Journal article published
    PubMed ID: 14680799
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  • 2
    Keywords: CANCER ; ANTIGEN ; PROGNOSTIC VALUE ; SERUM ; GEMCITABINE ; PANCREATIC-CANCER ; CEA ; BIOLOGICAL VARIATION ; CA19-9 gastrointestinal cancer antigen ; GI Monitor,pancreatic cancer ; IMMUNOASSAYS MARKER CA-19-9 ; method comparison,diagnosis ; TUMOR-ASSOCIATED ANTIGEN ; UTILITY
    Abstract: Background: This study was designed to investigate the clinical performance of the Access GI Monitor (Beckman Coulter) on the UniCel DxI 800, a method for CA19-9 antigen determination, and to compare with CA19-9 assay on the AxSYM system (Abbott). Methods: 1,063 serum samples from unselected patients with different underlying diagnoses were tested with both methods. Passing-Bablok regression analysis and Bland Altman analysis was performed. In addition, using ROC analysis, the distribution of Access Cl Monitor and AxSYM CA19-9 antigen levels was tested in patients with pancreatic cancer (n = 50), acute inflammatory disease (n = 20), and with chronic inflammation of the pancreatic gland (n = 18). Furthermore, four patients with pancreatic cancer were monitored individually in their courses of the disease (before, during, and after therapeutic procedures) to compare their CA19-9 values with regard to inter-method concordance. Results: Passing-Bablok analysis showed a systematic difference with R = 0.93, slope 0.75, and intercept -1.0. Bland Altman analysis showed a wide scatter of relative differences between both methods, especially in the low end measuring range. In the selected group of patients with pancreatic diseases the analysis of concordance revealed 95.5 % agreement between both methods with a comparable area under the ROC curves (0.73 vs. 0.76). A clear concordance was found for all four selected patients. Conclusions: Although we found significant systematic measuring variations in the global analysis, the two different automated methods for the quantitative determination of CA19-9 antigen were comparable with respect to their clinical accuracy and applicability to support decision making in the management of pancreatic cancer.
    Type of Publication: Journal article published
    PubMed ID: 20857896
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