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Biomedical subjects

K Schwarz

Publications and source records attributed to K Schwarz.

At least 145 records · Page 8Linked to original sources
PubMed1991

Severe combined immunodeficiency (SCID) in man: B cell-negative (B-) SCID patients exhibit an irregular recombination pattern at the JH locus.

Human severe combined immunodeficiency (SCID) patients were analyzed by a polymerase chain reaction assay for their recombination capability at the DHQ52-JH region of the immunoglobulin heavy chain locus. Five patients with B cells (B+ SCID) exhibited a recombination pattern also observed in healthy persons. In contrast, six patients lacking B cells (B- SCID) showed a grossly altered rearrangement pattern characterized by the (partial) absence of regular DHQ52-JH recombinations and the presence of abnormal rearrangements. These events were caused by deletions surpassing the boundaries of immunoglobulin coding elements and thus resemble the pattern of deletional recombinations previously described in SCID mice.

B-Lymphocytes↗
PubMed1990

Biosynthesis and properties of a further member of the small chondroitin/dermatan sulfate proteoglycan family.

Human osteosarcoma cells express a 78-kDa proteoglycan core protein to which an asparagine-bound oligosaccharide, O-glycosidically linked oligosaccharides and probably only a single chondroitin 6-sulfate chain of 29-kDa are bound. Prior to O-glycosylation, the N-glycosylated core protein exhibits a mass of 83 kDa. Upon digestion of the secreted proteoglycan with chondroitin ABC lyase a mature core protein with an apparent molecular mass of 106 kDa is obtained. Smaller amounts of core proteins of 101 and 115 kDa can be detected occasionally. The glycosaminoglycan composition and the relative molecular mass of the glycosaminoglycan chain distinguish this proteoglycan, tentatively named proteoglycan 100 (PG-100), from biglycan (small proteoglycan I) and decorin (small proteoglycan II) which are also expressed by osteosarcoma cells. An antiserum against PG-100 shows partial cross-reactivity with decorin, but in contrast to the latter proteoglycan it does not bind to type I collagen fibrils. PG-100 is not a unique product of osteosarcoma cells. It has also been found in the secretions of human skin fibroblasts.

Chondroitin Sulfate Proteoglycans↗
PubMed1989

Expression of an NCA cDNA in NIH/3T3 cells yields a 110K glycoprotein, which is anchored into the membrane via glycosyl-phosphatidylinositol.

The NCA cDNA, which represents a gene belonging to the CEA family, was inserted into an SV40 early promoter-driven expression vector and used for transfection of mouse NIH/3T3 cells. A cell line, NIH/3T3/KNCA IG7, was selected which expressed a molecule with an apparent molecular weight of 110,000. The mode of membrane attachment of this NCA, which we already proposed to be anchored via glycosyl-phosphatidylinositol, was investigated by treatment of NIH/3T3/KNCA IG7 cells with phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis. Two independent methods, flow cytometry and immunoprecipitation of [3H]-labelled surface glycoproteins, clearly demonstrated that the NCA molecule expressed by NIH/3T3/KNCA IG7 cells is indeed anchored into the membrane via glycosyl-phosphatidylinositol. Furthermore, these results support our previous biochemical data on NCA-50, by unequivocally showing that the NCA cDNA used for transfection encodes an NCA molecule related to NCA-50 and NCA-90.

Animals↗
PubMed1989

Non-specific cross-reacting antigen: characterization of specific and cross-reacting epitopes.

A cDNA for NCA-50 was cloned into the inducible expression vector pTRB1, using the polylinker site at the C-terminus of the lac Z' gene. An NCA-specific MAb (N1), NCA and CEA cross-reactive MAbs (T84.1, 192) and polyclonal antisera (anti-NCA and anti-CEA, as well as anti-PS beta G) detected the fusion protein, with a mol. wt of 155,000, which constituted about 5% of the total bacterial protein. Deletion and mutation analysis showed that all MAbs which stained positive in western blots mapped to a small region within the last third of the N-terminal domain. Superimposition of the deduced amino acid sequence of NCA-50 on the known structure of immunoglobulins reveals that the antigenic region is located on a surface loop, which corresponds to a fourth hypervariable region on the immunoglobulin heavy chain variable regions. By oligonucleotide directed site-specific mutagenesis amino acids were deduced, which constitute part of an epitope, to which the NCA-50-specific MAb, N1, binds.

Amino Acid Sequence↗
PubMed1988

Protein analysis of NCA-50 shows identity to NCA cDNA deduced sequences and indicates posttranslational modifications.

The amino acid sequence, representing 59% of the protein moiety of NCA-50 (nonspecific crossreacting antigen), has been determined. These data confirm that NCA-50 is the product of the mRNA whose corresponding cDNAs were recently isolated from a human lung (HLC-1), as well as from a colon carcinoma cell line (SW 403) cDNA library. The four cysteine residues detected in the NCA-50 molecule form disulfide bonds. The glycosylation of 7 potential N-glycosylation sites which were analysed, showed pronounced differences. There is strong evidence that NCA-50 is bound to a phosphatidyl-inositol glycan, via an amide linkage to ethanolamine at amino acid position 287, which has replaced the last 24 amino acids.

Amino Acid Sequence↗
PubMed1988

Analysis of the specificity of CEA reactive monoclonal antibodies. Immunological support for the domain-model of CEA.

A panel of 17 monoclonal antibodies (MAbs), which are reactive with purified carcinoembryonic antigen (CEA), was tested. The MAbs were categorized into 6 groups according to their reactivity with CEA 180, CEA 160, non-specific cross-reacting antigen (NCA) 97 and NCA 50. After chemical modification of CEA (reduction, carboxymethylation, deglycosylation, enzymatic cleavage) and binding studies, the MAbs were further divided into 8 subgroups, representing 8 different antigenic sites on CEA. All MAbs bind to deglycosylated CEA. Most of the MAbs are directed against conformational determinants, since only three of them recognize reduced and alkylated CEA. The same three MAbs are able to detect 29 kDa glycosylated fragments obtained by enzymatic cleavage of CEA. These three protease V8- and trypsin-resistant fragments, probably obtained by interdomain cleavage, show a close relationship in peptide patterns, supporting the repeating structural domain-model of CEA as deduced from the cDNA sequence of CEA.

Antibodies, Monoclonal↗