Biomedical subjects
C Nager
Publications and source records attributed to C Nager.
Isolation and characterization of a cartilage-specific membrane antigen (CH65): comparison with cytokeratins and heat-shock proteins.
We report the isolation and characterization of a 65,000 MW chondrocyte autoantigen (CH65) which may be involved in rheumatoid arthritis. This chondrocyte-specific antigen reacted with sera from patients with rheumatoid arthritis (RA). CH65 did not cross-react with a polyclonal antibody raised against microbial heat-shock protein (hsp) 65, anti-human hsp 65 monoclonal antibodies (mAb) (LK1 and LK2), anti-microbial hsp 65 mAb (IA10, IIC8 and WTB-78H1) and anti-cytokeratin 8, 18, 19 mAb (NCL5D3MAb). CH65 could be purified from chicken chondrocyte membranes by ammonium sulphate precipitation and a novel electro-gel-filtration method. The amino acid analysis yielded an unusually high degree of glycine, serine and asparagine residues. The internal amino acid sequence obtained by tryptic digestion revealed homologies with the cytokeratin family. Despite these homologies, CH65 lacked immunological cross-reactivity with commercial anti-cytokeratin antibodies. Mice mAb generated against the purified CH65 (C6) were used to identify the protein as a tissue-specific constitutive protein membrane from chondrocytes. Sera from patients with RA cross-reacted with purified CH65. The stress or heat-shock protein (hsp 65), implicated in the development of experimental and clinical arthritis, showed no immunological cross-reactivity with CH65 in Western blots. These findings suggest that CH65 may represent an interesting cartilage-specific new antigen in RA. The availability of this antigen in purified form and specific mAb may offer useful tools in arthritis research.
Interleukin-8 is a cyclosporin A binding protein.
Inflammatory immune reactions occur during transplant rejections and autoimmune diseases. Such reactions are mediated by cytokines, including interleukin-8 (IL-8). Cyclosporin A (CsA) exerts immunosuppressive activities by binding to immunoregulatory proteins termed cyclophilins. The anti-inflammatory effects of CsA are still not fully understood. Searching for novel neutrophil-activating proteins, we observed that an antiserum against human recombinant Interleukin-8 (IL-8) cross-reacted with cyclophilins in Western blots. Furthermore, native IL-8 was found to specifically bind CsA, whereas biologically inactive analogs of CsA were not bound by IL-8. Putative binding sites for CsA on IL-8 could be identified on the basis of structural similarities between IL-8 and cyclophilin. However, IL-8 lacks peptidyl-prolyl-isomerase (PPlase) enzyme activity, which is regarded as a characteristic of cyclophilins. We conclude that the specific binding of CsA to IL-8 may explain some of the anti-inflammatory effects of CsA. IL-8 may be a novel member of the cyclophilins lacking PPlase activity.
Continuous subcutaneous insulin infusion in an obese insulin-resistant pregnant woman with type II diabetes: accelerated fetal growth and neonatal complications.
This is the first report to describe prolonged continuous subcutaneous insulin infusion in a massively obese insulin-resistant pregnant woman with type II diabetes. Maternal 24-hour plasma glucose levels became normal by 48 hours, and normoglycemia was maintained with high daily doses of insulin (530 U-333 U/24 hours) from 29 weeks' gestation until delivery at 38.5 weeks. Excellent diabetic control was associated with euglycemia, normal glycosylated hemoglobin concentration, and a significant decrease in mean 24-hour plasma C-peptide (P less than .004) and glucagon (P less than .003) levels. Unexpectedly, fetal growth accelerated during constant insulin infusion despite normal maternal plasma glucose levels. The newborn infant was large (4530 g), with a striking truncal accumulation of fat, hypoglycemia (30-minute plasma glucose 11 mg/dL), and polycythemia (central venous hematocrit 71%). Normalization of maternal plasma glucose levels failed to ameliorate established macrosomia, and did not prevent the neonatal complications that are common in infants of diabetic mothers.
Cloning and expression of cDNA encoding mouse tyrosinase.
We have isolated a pigment cell-specific cDNA clone from a B16 mouse melanoma cDNA library by differential hybridization. The mRNA of isolated cDNA is highly expressed in B16 melanoma cells and in black mouse (C57BL/6) skin, but is not detectable in mouse neuroblastoma cells nor in K1735 mouse amelanotic melanoma cells. The protein sequence deduced from the nucleotide sequence of the cloned cDNA shows significant similarity to the entire region of Neurospora tyrosinase. To know the identity of cDNA, we transfected K1735 amelanotic melanoma and COS-7 cells with the cDNA carried in a simian virus 40 vector (pKCRH2). We confirmed that the isolated cDNA encodes mouse tyrosinase by immunofluorescence staining of transfected cells using two different anti-T4-tyrosinase monoclonal antibodies. Tyrosinase is composed of 513 amino acids with a molecular weight of 57,872 excluding a hydrophobic signal peptide of 24 amino acids.
The nucleotide sequence recognised by the Escherichia coli D type I restriction and modification enzyme.
A type I restriction endonuclease from a new isolate of Escherichia coli (E. coli E166) has been purified and characterised. The enzyme, EcoD, has a recognition sequence similar in overall structure to the previously determined type I enzyme sequences, an exception being that it is degenerate. The sequence is 5'-T-T-A-N-N-N-N-N-N-N-G-T-C-Y-3' 3'-A-A-T-N-N-N-N-N-N-N-C-A-G-R-5' where Y is a pyrimidine, R is a purine and N can be any nucleotide. The enzyme methylates adenosyl residues in both strands of the DNA that are separated by ten base pairs, suggesting that the enzyme interacts with DNA along one face of the helix making contacts in two successive major grooves.
[On glycoproteins from the human aorta. II].
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