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C Welter

Publications and source records attributed to C Welter.

At least 37 records · Page 2Linked to original sources
PubMed1998

Invasion of human cartilage by cultured multicellular spheroids of rheumatoid synovial cells--a novel in vitro model system for rheumatoid arthritis.

OBJECTIVE: A new 3-dimensional cell culture system was established to examine the invasion of rheumatoid synovial cells into cartilage. METHODS: Synovial cells from 20 patients with rheumatoid arthritis (RA) and 15 patients with osteoarthritis (OA) were co-cultured as multicellular spheroids with cartilage fragments. RESULTS: After 4 weeks the rheumatoid spheroids eroded the cartilage. The destruction of cartilage was supported by a high expression level of cathepsin D and matrix metalloproteinases. In contrast, the OA tissue showed attachment to the cartilage only. CONCLUSION: Our results indicate that spheroid/cartilage co-cultures seem to be a suitable in vitro model for the study of destructive cellular mechanisms that occur in RA.

Arthritis, Rheumatoid↗
PubMed1997

Identification of human semaphorin E gene expression in rheumatoid synovial cells by mRNA differential display.

Rheumatoid arthritis (RA) is characterised by chronic inflammation of synovial tissue with aggressive proliferation of synovial cells causing destruction of cartilage and bone. Immunopathological mechanisms, infectious causes and genetic factors have been discussed, but the etiology of the disease has not been understood until now. Especially, the mechanisms driving tumourlike growth and invasive behaviour of fibroblastoid synovial cells have not been identified yet. Our aim is to find cellular factors which are mediators for such pathways. One possibility to approach this, is searching for disease-relevant genes. We applied the mRNA-differential display technique to compare mRNA expression patterns of normal and rheumatic synovial fibroblasts. We identified an upregulation of the human semaphorin E gene in rheumatoid synovial fibroblastoid cells. Interestingly semaphorin E is a member of a protein-family described to play an immunosuppressive role via inhibition cytokines. A relevance of this finding towards the pathogenesis of RA is discussed.

Arthritis, Rheumatoid↗
PubMed1997

Oral administration of iopentol (Imagopaque 300 mg I/ml) compared with amidotrizoate (Peritrast 300 mg I/ml), both diluted to 2% (v/v), in imaging of the gastrointestinal tract in abdominal contrast enhanced CT. A clinical trial assessing patient tolerance, distribution of contrast medium and Hounsfield unit measurements.

The aim of the trial was to evaluate and compare the safety and efficacy of iopentol (Imagopaque, Nycomed Imaging AS, Oslo, Norway) and amidotrizoate (Peritrast, Köhler Pharma, Alsbach, Germany), both 300 mg I/ml initially, but diluted to 2% (v/v) and administered orally. Sixty-four and 65 patients were included in the respective contrast medium groups. Portions of contrast medium, totally 1.51, were taken every 15 min during the hour before the examination. A standard radiological procedure for abdominal CT was followed. Nine percent of the patients in each group experienced adverse events which were possibly contrast medium related. Taste acceptance was comparable in the two groups. Except for the stomach, radiographic efficacy was satisfactory for all intestinal segments. The difference in density in the proximal small bowel (main parameter) achieved with the media was not significant (p = 0.33), nor was that as regards image homogeneity (contrast distribution). In conclusion, iopentol is well suited for oral contrast enhancement of the gastrointestinal tract in abdominal computed tomography.

Administration, Oral↗
PubMed1997

Isolation and characterization of new microsatellites at the nm23-H1 and nm23-H2 gene loci and application for loss of heterozygosity (LOH) analysis.

The nm23-H1 gene has been suggested to be a metastasis suppressor gene. Studies about the events of loss of heterozygosity (LOH) at the nm23 locus and its correlation to metastasis are controversially discussed. To optimize detection of LOH at the nm23 locus, we screened two P1 clones for additional microsatellites. Tumor and normal DNA from 37 colorectal, 16 gastric, and 8 germ cancer patients were examined for LOH. We found two new CA repeats, one 5' to nm23-H1 and another 3' to nm23-H2. Using these nm23 locus-specific CA repeats and five other chromosome 17 loci (D17S1522, D17S1566, D17S855, D17S515, and TP53), allele loss was observed in 4/32 (12.5%) patients with colon cancer, 2/14 (14.3%) with gastric cancer, and 1/7 (14%) with germ cancer. No isolated LOH of the nm23 region was observed.

Aged↗
PubMed1997

Expression of the candidate tumor suppressor gene nm23 in the bronchial system of patients with squamous cell lung cancer.

OBJECTIVE: A number of oncogenes and tumor suppressor genes participating in tumorigenesis have been identified, one of them being nm23. The expression of the candidate tumor suppressor gene nm23 depends on the cell type of tumors. Both, reduced expression as well as overexpression of nm23 is associated with a high potential of malignancy. In a variety of tumor cell lines secretion of the nm23 protein can be detected. In an earlier investigation we showed, that the nm23 expression in squamous cell lung carcinoma is considerably elevated. In order to establish the potential diagnostic value of this finding we investigated the nm23 expression in healthy and diseased lungs in patients with squamous cell lung cancers. METHODS: We examined bronchial lavage samples of 20 patients with bronchogenic squamous cell carcinoma. The lavage was separately performed in the bronchus of the tumor bearing lobe and in the corresponding bronchus of the unaffected contralateral lung. RESULTS: Using Western blot analysis we found 2-7 fold elevated amount of nm23 protein in bronchial lavage of the tumor bearing lung in comparison to the healthy side. This finding was neither related to tumor stage nor to tumor location. Thus we have a strong hint that the nm23 protein is secreted by the bronchogenic squamous cell carcinoma. CONCLUSIONS: With respect to these results the proof of nm23 protein in bronchial lavage fluid might be of relevance to establish the diagnosis when pulmonary nodules of unknown etiology are found.

Biomarkers, Tumor↗
PubMed1996

Inhibition of nucleoside diphosphate kinase activity by in vitro phosphorylation by protein kinase CK2. Differential phosphorylation of NDP kinases in HeLa cells in culture.

Although a number of nucleoside diphosphate kinases (NDPKs) have been reported to act as inhibitors of metastasis or as a transcription factor in mammals, it is not known whether these functions are linked to their enzymatic activity or how this protein is regulated. In this report, we show that in vitro protein kinase CK2 catalyzed phosphorylation of human NDPK A inhibits its enzymatic activity by inhibiting the first step of its ping-pong mechanism of catalysis: its autophosphorylation. Upon in vivo 32P labeling of HeLa cells, we observed that both human NDPKs, A and B, were autophosphorylated on histidine residues, however, only the B isoform appeared to be serine phosphorylated.

Casein Kinase II↗
PubMed1996

Specific in vitro binding of p53 to the promoter region of the human mismatch repair gene hMSH2.

MSH2 is one of the genes involved in DNA-mismatch repair. Mutations in the coding region of the human gene (hMSH2) have been shown to be directly involved in microsatellite instability in hereditary nonpolyposis colorectal tumors. Examination of the promoter region of hMHS2 revealed a site with homology to the p53 consensus binding sequence. Using gel mobility shift experiments we were able to show that purified p53 has at least in vitro the potential to specifically bind the hMSH2-p53 motif. This binding activity was even stronger than the binding activity measured with the p53-consensus site. These data identify the hMSH2 gene as a possible novel p53-regulated target gene and indicate a direct involvement of p53 in repair mechanisms via DNA binding of a mismatch repair gene.

Animals↗
PubMed1996

Isolation and characterization of the human mismatch repair gene hMSH2 promoter region.

Hereditary nonpolyposis colorectal cancer (HN-PCC) is one of man's commonest hereditary diseases. Several studies have identified four responsible genes that are involved in a process known as DNA mismatch repair; hMSH2 is the most important of these four genes. In addition to mutational analysis of these genes, investigations of transcriptional regulatory mechanisms are important. Therefore, our purpose has been to isolate the hMSH2 promoter region. Using direct sequencing of P1 recombinant DNA we have characterized 1100 bp of the hMSH2 promoter.

Base Sequence↗
PubMed1996

A second trefoil protein, ITF/hP1.B, is transcribed in human breast cancer.

Trefoil proteins form a specific group of stable secreted polypeptides. They are expressed in a lot of human cancers and during inflammatory processes of the gastrointestinal tract. Recently a new human trefoil protein, ITF/hP1.B, was isolated. Until now no studies of the activity of this gene in human solid tumors exist. In our examination we show for the first time that this gene is transcribed in human breast cancer. In contrast to another trefoil protein, pS2, the expression of ITF/hP1.B is not under control of estrogen in the human breast cancer cell line MCF-7. We suggest that the gene activity of ITF/hP1.B in addition to pS2 expression may be an improved prognostic marker in human breast cancer.

Biomarkers, Tumor↗
PubMed1996

c-myb intron I protein binding and association with transcriptional activity in leukemic cells.

Specific binding of nuclear proteins to the region of transcriptional attenuation has been shown to modulate the expression of c-myb, a nuclear proto-oncogene preferentially expressed in lympho-hematopoietic cells. Here, it plays an important role in processes of differentiation and proliferation. The mechanism that regulates c-myb expression is not yet fully understood. The block of transcriptional elongation which has been mapped to a 1 kb region within murine intron 1 may represent one regulatory pathway. The DNA sequences containing the transcriptional pause site are well conserved between murine and human species, thus Implying similar transcription-control strategies. We compared the binding potential of nuclear extracts (from human fibroblasts and MOLT4 as well as murine NIH3T3- and 70Z/3B- cell lines) to oligonucleotide sequences previously shown to be target binding sites in the murine system. One complex containing a 70 D protein was found to be associated specifically with transcriptionally active leukemia cells. We performed transient expression studies with a CAT reporter construct containing this putative enhancer sequence and yielded significant CAT activity. We identified further a putative 20 kD repressor protein in transcriptionally silent cells and demonstrated that c-Jun is part of an ubiquitously present complex. Our results confirm the participation of intron 1 in transcriptional regulation of the c-myb gene (in mouse and human) and implicate multiple and complex regulatory mechanisms of activation during myelomonocytic differentiation and leukemic cell growth control.

3T3 Cells↗
PubMed1996

Constitutive expression of c-fos and c-jun, overexpression of ets-2, and reduced expression of metastasis suppressor gene nm23-H1 in rheumatoid arthritis.

OBJECTIVES: To identify genes that are involved in the development and progression of rheumatoid arthritis (RA). METHODS: We used a multiple gene analysis system and a set of available genes participating in processes such as proliferation, differentiation, tumour progression, and metastasis, to identify their RA related expression. Synovial tissues from 22 patients with RA were evaluated in comparison with those from six patients with osteoarthritis and two patients with non-inflamed joints as controls, using northern blot and reverse transcriptase polymerase chain reaction experiments. RESULTS: Our data confirm the role of c-fos and c-jun as constitutive signal transmitters in solid RA tissues, thus demonstrating the potential of the approach. Activation of both genes persisted through multiple passages of the cells in tissue cultures derived from the synovial lining of RA tissues. There was an increased expression of ets-2 in 30% of RA samples and an up to 30-fold decreased expression of the potential metastasis suppressor gene nm23-H1 in 90% of RA tissues, compared with control tissues. CONCLUSIONS: The data presented show for the first time a significant decrease of nm23-H1 expression in RA, which is possibly involved in local invasiveness, and a strong activation of the ets-2 nuclear oncogene in about one third of RA tissues, which may also be part of a pathway leading to advanced disease stages. The constitutive expression of c-fos and c-jun in RA tissue most probably results from a continuing inflammatory stimulus. These findings with cell cultures suggest an intrinsic activation mechanism of these early response genes in RA.

Arthritis, Rheumatoid↗
PubMed1996

A third P-domain peptide gene (TFF3), human intestinal trefoil factor, maps to 21q22.3.

Small peptides displaying a cysteine-rich module (termed P-domain or trefoil motif) form a recently increasing group of peptides abundantly expressed at mucosal surfaces of specific tissues and are associated with the maintenance of surface integrity. The estrogen-inducible pS2 gene (BCEI) and the human homolog to the porcine spasmolytic peptide (hsP) gene (SML1) appear synchronously expressed in healthy stomach mucosa and several carcinomas of the gastrointestinal tract. Both genes were shown to be located at 21q22.3. A new trefoil peptide from human intestinal mucosa (hITF/hP1.B) and its gene (TFF3) were described recently. By PCR analysis of a somatic cell hybrid panel and FISH using two large genomic recombinants (110 kb, 210 kb) cloned in the Bacterial Artificial Chromosome (BAC) system, we show that this gene coding for the new member of human P-domain/trefoil peptides also maps to chromosome region 21q22.3 suggesting a physical linkage of all three trefoil peptide genes.

Amino Acid Sequence↗
PubMed1995

A novel serine/threonine-specific protein phosphotransferase activity of Nm23/nucleoside-diphosphate kinase.

Two human nm23 genes have been identified, designated nm23-H1 and nm23-H2, which encode the 88% identical nucleoside-diphosphate kinase (NDPK) A and NDPK B polypeptides, respectively. The nm23-H1 gene product has been shown to play a functional role in the suppression of tumor metastasis. The Nm23 proteins/NDPK are highly conserved throughout evolution and are implicated in controlling cellular differentiation and development in various species, while the underlying mechanisms remain undefined. Neither the NDPK activity nor the DNA-binding activity, identified recently for NDPK B, can satisfactory explain the regulatory functions of Nm23. The present study provides evidence that purified Nm23 proteins are capable of transferring a phosphate group to other proteins when non-denaturing amounts of urea are present. This novel Nm23/NDPK activity was found to be specific for serine and threonine residues, and the transphosphorylation of substrate proteins occurred stoichiometrically. Because of the absence of a substrate turn-over, the novel function was termed protein phosphotransferase activity instead of protein kinase activity. It is demonstrated that urea stimulates the interaction of NDPK with other proteins. Identical phosphoprotein patterns were obtained using purified NDPK preparations from human, Drosophila, yeast and Dictyostelium in the presence of urea. Partially purified NDPK from human erythrocytes produced a similar phosphorylation pattern independent of urea addition and also acted stoichiometrically. In this preparation, a protein phosphotransferase activity of Nm23 species may possibly be generated and/or stabilized by the interaction with copurified proteins. Using different mutants of Dictyostelium NDPK it was shown that the protein phosphotransferase activity depends on the same active site as the NDPK activity. A phosphotransfer mechanism analogous to that of protein-histidine kinases is proposed, involving a high-energy phosphohistidine intermediate. Furthermore, the novel Nm23 function is compared with an apparently similar protein phosphotransferase activity which was observed previously with partially purified NDPK from different plant species.

Amino Acids↗
PubMed1995

Characterization of the human nm23-H2 promoter region and localization of the microsatellite D17S396.

The transcription of human nm23 genes (nm23-H1, nm23-H2) is involved in suppression of tumor metastasis or tumor progression. Therefore the characterization of transcriptional regulatory mechanisms for both nm23 genes is very important. In this study we have isolated and analyzed the 5'-flanking region of the human nm23-H2 gene and estimated the distance to 4 kb between nm23-H2 and nm23-H1 genes. We localized the known microsatellite D17S396 within this region. Furthermore the identification of possible binding sites for MYC proteins and additionally the NM23-H2 protein itself (the transcription factor PuF for c-myc gene activation) is of importance with respect to possible para- and autoregulatory interactions. A comparison of the promoter sequences of both human nm23 genes revealed no significant sequence homology.

Animals↗
PubMed1995

Differential expression of heat shock protein 70 in well healing and chronic human wound tissue.

Heat shock protein 70 (hsp 70) is an important member of the heat shock protein family, which is induced by different forms of stress. We attempted to find out if hsp 70 is also involved in wound healing, which likewise resembles a stress situation for cells too. Therefore we collected tissue samples from well healing and chronic human wound tissue. We used Northern- and Western-blot analysis to study the expression of hsp 70. At the protein level we found a strong correlation between well healing wounds and high expression of hsp 70, whereas chronic wounds showed no or weak expression. Interestingly hsp 70 mRNA did not show this significant correlation, displaying a variant expression pattern in the same kind of wound tissue, possibly due to unknown posttranscriptional regulating step, which has to be investigated in further studies. To localize hsp 70 mRNA and protein was used insitu hybridization and immunohistochemistry. Both displayed an overexpression in endothelial cells of capillary vessels.

Base Sequence↗
PubMed1995

Characterization of the genomic structure and the promoter region of the human intestinal trefoil factor.

Trefoil proteins form a specific group of stable secretory polypeptides. They are expressed in a lot of human cancers and inflammatory processes of the gastrointestinal tract. Recently a new human trefoil protein, ITF/hP1.B was isolated. This gene is expressed mainly in globet cells of intestinum and colon. The genomic structure of the murine and rat homologues genes were described previously and a high nucleotide sequence conservation (78-95%) was found in the coding as well as the regulatory regions. We have isolated the human genomic ITF-gene region from a P1 library and a detailed analysis yielded in a similar gene structure with a three basepair displacement of the second exon intron boundary. The promoter region of the human gene interestingly is markedly different from rat and mouse.

Amino Acid Sequence↗
PubMed1995

Coexpression pattern of c-myc associated genes in a small cell lung cancer cell line with high steady state c-myc transcription.

The c-Myc protein is involved in cellular transformation and mitogenesis, but also works as a potent inducer of differentiation and programmed cell death. Max as an obligate heterodimeric partner for Myc mediates its functions as a specific transcriptional activator and a transforming protein. Mad and Mxi1 proteins both heterodimerize with Max and compete with each other for limiting amounts of Max. Transcriptional activation by Myc can be suppressed by increasing the amount of Mad or Mxi1. This report shows the expression pattern of these Myc related factors at the mRNA level in a small cell lung cancer (SCLC) cell line (GLC4) which is characterized by c-myc amplification and strong constitutive c-myc overexpression. We found these genes transcriptionally active but uninfluenced from high c-myc transcription. Max was constantly transcribed at a relatively low level during cell cycle progression. Mad and mxi1 mRNA was at a surprisingly high level in proliferating cells. Mad was further upregulated and mxi1 was downregulated to basal levels during serum starvation of the cells. We further analyzed the activity of c-fos, c-jun, c-myb and nm23 which are described to be involved in c-myc transcriptional activation, c-jun and c-fos were not constitutively activated and can be excluded as regulators. High steady state c-myc in contrast influences the serum stimulated transient activation mechanism of these two genes. We identified high copy number nm23 mRNA whose role as a putative c-myc transcriptional activator is under investigation. Our results indicate that constitutive overexpression of c-myc does not require the activity of the nuclear oncogenes tested and that the m-RNA expression pattern of functionally related proteins is not influenced.

Base Sequence↗