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Biomedical subjects

T Kirchner

Publications and source records attributed to T Kirchner.

At least 73 records · Page 4Linked to original sources
PubMed2000

Rapid and specific detection of Helicobacter pylori macrolide resistance in gastric tissue by fluorescent in situ hybridisation.

BACKGROUND: The development of macrolide resistance in Helicobacter pylori is considered an essential reason for failure of antibiotic eradication therapies. The predominant mechanism of resistance to macrolides, particularly clarithromycin, is based on three defined mutations within 23S rRNA, resulting in decreased binding of the antibiotic to the bacterial ribosome. AIM: To develop an rRNA based whole cell hybridisation method to detect Helicobacter species in situ within gastric tissue, simultaneously with its clarithromycin resistance genotype. METHODS: A set of fluorescent labelled oligonucleotide probes was developed, binding either to H pylori 16S rRNA or 23S rRNA sequences containing specific point mutations responsible for clarithromycin resistance. After hybridisation and stringent washing procedures, labelling of intact single bacteria was monitored by fluorescence microscopy. The new approach was compared with PCR based assays, histology, and microbiological culture. RESULTS: In comparison with the phenotypic resistance measurement by E test, the genotypic clarithromycin resistance correlated perfectly (100%) for 35 H pylori isolates analysed. In a set of gastric biopsy specimens (27) H pylori infection was confirmed by histology (17/27) and correctly detected by whole cell hybridisation. Five clarithromycin resistant strains were identified in gastric tissue specimens directly. Furthermore, non-cultivable coccoid forms of H pylori were easily detectable by whole cell hybridisation. CONCLUSIONS: Whole cell hybridisation of rRNA holds great promise for cultivation independent, reliable, and rapid (three hours) genotypic determination of clarithromycin resistance in H pylori. Compared with PCR techniques it is independent of nucleic acid preparations, not prone to inhibition, and allows semiquantitative visualisation of the bacteria within intact tissue samples.

Anti-Bacterial Agents↗
PubMed2000

The Vienna classification of gastrointestinal epithelial neoplasia.

BACKGROUND: Use of the conventional Western and Japanese classification systems of gastrointestinal epithelial neoplasia results in large differences among pathologists in the diagnosis of oesophageal, gastric, and colorectal neoplastic lesions. AIM: To develop common worldwide terminology for gastrointestinal epithelial neoplasia. METHODS: Thirty one pathologists from 12 countries reviewed 35 gastric, 20 colorectal, and 21 oesophageal biopsy and resection specimens. The extent of diagnostic agreement between those with Western and Japanese viewpoints was assessed by kappa statistics. The pathologists met in Vienna to discuss the results and to develop a new consensus terminology. RESULTS: The large differences between the conventional Western and Japanese diagnoses were confirmed (percentage of specimens for which there was agreement and kappa values: 37% and 0.16 for gastric; 45% and 0.27 for colorectal; and 14% and 0.01 for oesophageal lesions). There was much better agreement among pathologists (71% and 0.55 for gastric; 65% and 0.47 for colorectal; and 62% and 0.31 for oesophageal lesions) when the original assessments of the specimens were regrouped into the categories of the proposed Vienna classification of gastrointestinal epithelial neoplasia: (1) negative for neoplasia/dysplasia, (2) indefinite for neoplasia/dysplasia, (3) non-invasive low grade neoplasia (low grade adenoma/dysplasia), (4) non-invasive high grade neoplasia (high grade adenoma/dysplasia, non-invasive carcinoma and suspicion of invasive carcinoma), and (5) invasive neoplasia (intramucosal carcinoma, submucosal carcinoma or beyond). CONCLUSION: The differences between Western and Japanese pathologists in the diagnostic classification of gastrointestinal epithelial neoplastic lesions can be resolved largely by adopting the proposed terminology, which is based on cytological and architectural severity and invasion status.

Adenoma↗
PubMed2000

Cell populations involved in pigmented villonodular synovitis of the knee.

OBJECTIVE: Pigmented villonodular synovitis (PVNS) of the knee is a tumor-like process of uncertain nature. We analyzed the involved cell populations, iron deposition, and cell proliferation in PVNS to propose a pathogenetic concept of this still elusive disease entity. METHODS: The study was performed on a series of 14 cases of localized PVNS of the knee. Histology and histochemistry were used to evaluate basic morphology and iron deposit distribution. Immunohistochemistry was performed to characterize the inflammatory cell infiltrate and to identify the proliferating cell compartments. In situ hybridization analysis using a cDNA probe against type I collagen was utilized to further characterize the mononuclear cell infiltrate. RESULTS: In addition to the classic features (mononuclear cell infiltrate, multinuclear giant cells, iron deposits, and stromal fibrosis) we observed a chronic inflammatory cell infiltrate in all PVNS samples, in which CD8 positive T cells were conspicuous. A high portion of non-phagocytotic cells resorbed iron and became CD68 positive. A proportion of mononuclear cells expressed type I collagen, thus resembling B synoviocytes. CONCLUSION: Our results suggest that preexisting chronic inflammation plays an important pathogenetic role in the PVNS disease process. Chronic inflammation increases the risk of articular bleeding and probably deranges the iron processing capacity of local synovial macrophages. The resulting iron overload could lead to a shift of iron storing cells from synovial macrophages to B synoviocytes and fibroblasts. A perpetuated proliferation and activation of these cells can explain why PVNS behaves like a neoplastic process.

Adult↗
PubMed2000

[beta-Catenin induces invasive growth by activating matrix metalloproteinases in colorectal carcinoma].

beta-catenin was shown to be a major oncoprotein in colon cancer development. Its oncogenic function as a transcriptional activator is upregulated by mutations in the APC tumor suppressor gene, leading to a constitutive activation of the proliferation-associated genes c-myc and cyclin D. The aim of this study was to demonstrate a role of APC-mutations and dysregulated beta-catenin also for the progression of colorectal cancer, by identifying new target genes of beta-catenin associated with tumor invasion and metastasis. Potential invasion genes regulated by beta-catenin and its DNA binding partner TCF4 were identified by a computer search for the consensus DNA binding sequence in relevant promoter regions. Specific DNA binding was confirmed by gel shift assays. Functional importance of beta-catenin for the activation of identified genes was determined by luciferase reporter assays. The significance was demonstrated by coexpression of nuclear beta-catenin and the identified target genes by immunohistochemistry. Among other invasion genes, we identified the matrix metallo proteinases MMP-7 and MMP-1 activated by beta-catenin in the tumor cells. MMP-7 is an important factor for invasion and metastasis and overexpressed in 75% of colon carcinomas. The significance for human colon cancer development was demonstrated by a correlated overexpression of beta-catenin and the MMPs, beginning in large, severely dysplastic adenomas. Our results explain the high percentage of MMP-7 overexpression in colorectal tumors and the resulting activation of invasive growth. Moreover by identifying dysregulated beta-catenin as a transcriptional activator of MMPs and other invasion factors, we demonstrated an important role of mutated APC not only for early steps but also for the progression of colorectal carcinogenesis.

Cadherins↗
PubMed2000

Tumor patterning: analogies of neoplastic morphogenesis with embryogenesis.

Patterning or pattern formation is a spatial and temporal process, by which ordered arrangements of cells and tissue structure are attained. The term is mostly applied to the morphogenesis in developmental biology, but it can also be useful for the neomorphogenesis in tumor biology. Despite increasing data on the proliferation and differentiation of tumor cells, processes of tumor patterning are rarely studied and poorly understood. A fundamental embryonic process of patterning is the gastrulation and a basic example of neoplastic patterning is the colonic adenoma-carcinoma sequence. Both processes exhibit distinct nuclear translocations and expressions of beta-catenin, which is considered to be a decisive transcriptional regulator. Our recent studies demonstrate striking analogies of patterning and nuclear beta-catenin expressions between the colonic adenoma-carcinoma sequence and the gastrulation steps. The shared patterns are dissociation, reassembly, tubular reconstruction and branching of neoplastic cells in association with nuclear beta-catenin expressions. These new findings establish patterning as a relevant concept for tumor biology and link the neoplastic morphogenesis with embryogenesis.

Body Patterning↗
PubMed1999

Expression of deoxyuridine triphosphatase (dUTPase) in colorectal tumours.

We report the generation of 2 monoclonal antibodies (MAbs), 2B12 and 3E6, suitable for the detection of human dUTPase in routinely processed paraffin sections by immunohistochemistry. Using these MAbs, we observed nuclear expression of dUTPase in the proliferation zones of normal colorectal mucosa as well as in hyperplastic polyps. Colorectal adenomas and adenocarcinomas revealed a wide spectrum of dUTPase expression, ranging from 5 to 63% (median 42%) and from 5 to 71% of tumour cells (median 42%) respectively. Non-parametric correlation of dUTPase expression with proliferation as determined by a Ki-67 antigen-specific MAb revealed a significant and moderately strong correlation between proliferation rate and dUTPase expression in adenomas, but not in adenocarcinomas. This finding was confirmed by double-labelling immunofluorescence. Unexpectedly, we found significantly lower levels of dUTPase expression in primary colorectal carcinomas without lymph-node metastases at the time of surgery (Dukes A and B stages) than in Dukes C carcinomas. While this observation requires confirmation in larger studies, it suggests that dUTPase expression may be a negative prognostic marker in colorectal carcinomas. Moreover, these reagents should prove useful in the context of attempts to develop dUTPase inhibitors for cancer chemotherapy. Since it has been demonstrated that dUTPase expression can mediate resistance to 5-fluorouracil, it is also possible that these MAbs may be helpful in identifying patients with colorectal carcinomas resistant to adjuvant chemotherapy using this and related compounds. Int. J. Cancer (Pred. Oncol.) 84:614-617, 1999.

Adenocarcinoma↗
PubMed1999

Chondroblastoma is an osteoid-forming, but not cartilage-forming neoplasm.

Chondroblastoma is defined as a 'benign tumour, characterized by highly cellular and relatively undifferentiated tissue composed of rounded or polygonal chondroblast-like cells' and the 'presence of cartilaginous intercellular matrix' (WHO). An extensive analysis of the extracellular matrix composition and gene expression pattern of a large series of chondroblastoma cases shows, however, that type II collagen, which is the main component of any cartilage matrix, is not expressed by the neoplastic cells of this tumour entity and is not deposited into the extracellular tumour matrix. Instead, osteoid and fibrous matrix is formed, with its typical biochemical composition. The multifocal expression of aggrecan proteoglycan in most chondroblastomas explains the bluish, pseudo-chondroid appearance of some of the matrix-rich areas of chondroblastomas. This study did not show chondroid matrix formation or chondroblastic cell differentiation in chondroblastomas, suggesting that chondroblastoma should be classified as a specific bone-forming, rather than cartilage-forming neoplasm.

Aggrecans↗
PubMed1999

[EHBMP-2. Initial BMP analog with osteoinductive properties].

For the first time a non natural BMP-variant (EHBMP-2) with osteoinductive properties was produced by expression in E. coli through specific mutation of the amino acid sequence. The substitution of 12 N-terminal amino acids by a nonsense sequence results in a neglectible affinity of EHBMP-2 to the extracellular matrix. In vitro EHBMP-2 induces dose-dependent cartilage formation in neonatal muscle tissue. Single intramuscular implantation in mice results in the formation of an ossicle with functional active bone marrow. The size of the ossicle depends on the amount of implanted EHBMP-2 and can significantly be increased by the combination with a collagen carrier. The largest bone formation is observed after injection of EHBMP-2 containing collagen suspensions. In rats a stronger osteoinductive activity can be achieved by coupling of EHBMP-2 to collagen discs than by coupling natural BMP-2 to the same collagen carrier. Critical size defects in rats' mandibular angels can be restored by the combination of granular collagenous bone matrix (ICBM) with EHBMP-2. Further investigations have to show whether the altered pharmacokinetics of EHBMP-2 has advantages regarding its therapeutical use and tissue-engineering.

Amino Acid Substitution↗
PubMed1999

[Digital ischemia as paraneoplastic marker of metastatic endometrial carcinoma].

Digital ischemia with gangrene of one or several fingertips has been described as a paraneoplastic syndrome associated with various malignant tumors, especially adenocarcinomas. Most often this paraneoplastic syndrome represents the first symptom of an occult neoplasia in an advanced stage. We present the case of an 83 year-old patient with digital ischemia and gangrenous fingertips in association with a latent adenocarcinoma of the uterus and metastatic involvement of the paraaortal lymph nodes. Acute occurrence of digital ischemia and gangrene without pathological laboratory findings and negative past medical history concerning cardiovascular-induced emboli, arteriosclerotic occlusion, or rheumatologic and autoimmune diseases should suggest this paraneoplastic syndrome and lead to thorough search for an underlying tumor.

Aged↗
PubMed1999

beta-catenin regulates the expression of the matrix metalloproteinase-7 in human colorectal cancer.

Most colorectal cancers have loss of function mutations in the adenomatosis polyposis coli (APC) tumor suppressor gene. This leads to accumulation of beta-catenin, which together with the DNA binding protein TCF-4 functions as a transcriptional activator. Recently defined target genes are c-myc and cyclin D1, linking the APC gene defect to the capacity for autonomous proliferation of colon tumors. Here we report the identification of the matrix metalloproteinase MMP-7 as another target gene of beta-catenin/TCF-4. MMP-7 is overexpressed in 80% of human colorectal cancers and known to be an important factor for early tumor growth, with a potential function also for later progression steps, like invasion and metastasis. Our results explain the high percentage of MMP-7 overexpression in colon tumors. Moreover they indicate that defects in the APC tumor suppressor gene may also have an influence on later steps of colon tumor progression.

Biomarkers, Tumor↗
PubMed1999

Acute hepatitis induced by greater celandine (Chelidonium majus).

The hepatotoxic potential of conventional drugs is well known, but herbal medicines are often assumed to be harmless. In the last 2 years, we have observed 10 cases of acute hepatitis induced by preparations of greater celandine (Chelidonium majus), which are frequently prescribed to treat gastric and biliary disorders. The course of hepatitis was mild to severe. Marked cholestasis was observed in 5 patients, but liver failure did not occur. Other possible causes of liver disease (viral, autoimmune, hereditary, alcohol, and secondary biliary) were excluded by laboratory tests and imaging procedures, and liver biopsy specimens were consistent with drug-induced damage. After discontinuation of greater celandine, rapid recovery was observed in all patients and liver enzyme levels returned to normal in 2-6 months. Unintentional rechallenge led to a second flare of hepatic inflammation in 1 patient. Greater celandine has to be added to the list of herbs capable of inducing acute (cholestatic) hepatitis. A significant proportion of unexplained cases of hepatitis may be caused by greater celandine.

Acute Disease↗
PubMed1999

Decrease of antigastric autoantibodies in Helicobacter pylori gastritis after cure of infection.

H. pylori infection leads to the formation of autoantibodies against canalicular structures with human parietal cells in about 30% of all patients. This type of autoreactivity is associated with gastric mucosa atrophy. This study aimed to analyse the effect of cure of infection on anticanalicular autoantibodies. H. pylori infection was cured in 34 patients. Sera of these patients were screened for anticanalicular autoantibodies using an immunohistochemical method before, 10 weeks after and one year after cure of infection. Prevalence of anticanalicular autoantibodies significantly decreased from 26% before treatment to 9% after one year. The data presented in this study add new information to the possible reversibility of gastric mucosa atrophy.

Adult↗
PubMed1999

Pleomorphic adenomas of the parotid express different mesenchymal phenotypes: demonstration of matrix gene expression products characteristic of the fibroblastic and chondrocytic cell lineages.

AIMS: Pleomorphic adenomas of the salivary glands are characterized by their high tissue diversity. Many studies have explored the derivation and differentiation of the neoplastic cells. We investigated the composition of the collagenous extracellular tumour matrix and could show a specific biochemical composition pattern in the different tumour areas. METHODS AND RESULTS: In epithelially differentiated acinar and ductal areas there was positive staining for basement membrane collagen type IV and no, or only scarce, staining for collagen types I, II, III, or VI. Solid areas mostly lacked any extracellular matrix. In areas with fibrous tissue-like appearance, the fibroblast-typical interstitial collagen types I, III and VI were seen. Chondroid areas showed abundantly the characteristic cartilage components, collagen type II and, pericellularly, type VI collagen. CONCLUSIONS: Our data show the presence of fibroblastic and chondrocytic cell differentiation in pleomorphic adenomas. Thus, they confirm that these neoplasms display, besides epithelial cell types, also real mesenchymal cell and tissue types. Differences in the abundance and the biochemical composition of the extracellular tumour matrix account largely for the morphological heterogeneity of pleomorphic adenomas of the salivary glands.

Adenoma↗
PubMed1999

Helicobacter pylori induces apoptosis in gastric mucosa through an upregulation of Bax expression in humans.

BACKGROUND: Maintenance of gastric mucosal integrity depends on the balance between cell loss due to apoptosis and cell proliferation. Helicobacter pylori induces apoptosis in gastric epithelial cells, but the regulation of this process has been little studied. The Bcl-2 proteins are the best-studied family of proteins involved in the mechanism of apoptotic death. Some members of this family, such as Bcl-2, inhibit apoptosis, whereas others, such as Bax, induce it. The present study was performed to determine the apoptosis rate and mRNA and protein expression for Bax and Bcl-2 in the gastric mucosa of duodenal ulcer (DU) patients with H. pylori infection before and after H. pylori eradication. We recruited 8 H. pylori-negative control subjects and 20 DU patients (H. pylori-positive) given a 1-week triple therapy to eradicate H. pylori. The apoptosis was analyzed by means of terminal deoxyribonucleotide transferase-mediated digoxigenin-11-deoxyuridine triphosphate biotin nick-end labeling (TUNEL) staining, and the expression of mRNA for Bax and Bcl-2 by reverse transcription polymerase chain reaction (RT-PCR) and Southern blot. In all patients gastritis was assessed histologically on the basis of the Sydney classification, the presence of H. pylori, and analysis of cagA status. RESULTS: All 20 DU patients were H. pylori-positive, and 18 (90%) were CagA-positive. The apoptotic cells were infrequently identified in gastric surface epithelium by TUNEL histochemistry in H. pylori-negative controls. In DU patients infected with H. pylori, apoptotic cells were more numerous and seen deep in the gastric glands. The infection was associated with significantly upregulated expression of mRNA and protein for Bax and suppressed mRNA and protein expression for Bcl-2, as determined using RT-PCR and Western blot analysis. The Bax overexpression was significantly stronger in the antrum than in the corpus of H. pylori-infected patients. Four weeks after the eradication a marked decrease of neutrophil infiltration, an improvement of the grade of gastritis (mononuclear infiltration), and significant reduction in apoptosis rate were observed. After eradication the Bax mRNA expression was still at an increased level, whereas the Bcl-2 mRNA expression remained suppressed. CONCLUSIONS: 1) H. pylori induces apoptosis in the gastric epithelium, at least in part, due to an upregulation of proapoptotic Bax and downregulation of antiapoptotic Bcl-2, and 2) Bax mRNA and protein expression was higher in the antrum than in the corpus, and this was probably due to greater inflammatory changes observed in the antrum than in the corpus.

Adult↗
PubMed1999

Negative regulation of CD4 expression in T cells by the transcriptional repressor ZEB.

ZEB, an E-box binding transcriptional repressor, is an important regulator of T cell and muscle development. Targeted disruption of ZEB in mice resulted in a strong reduction of thymocytes and the few T cells that reached the mature stage were predominantly CD4(+). CD4 expression during the various stages of T cell differentiation is controlled at the transcriptional level by a complex array of regulatory elements in the CD4 gene locus, consisting of at least three enhancers, one promoter and one silencer. Here we present evidence that CD4 gene expression is negatively regulated by ZEB. We show that ZEB binds to the 5'E-box in the CD4-3 element of the proximal CD4 enhancer in competition with the transcriptional activators E12 and HEB, thereby reducing CD4 expression on CD4 single-positive but not CD4/CD8 double-positive T cells. The conversion of the CD4 proximal enhancer into a potential silencer element by the transcriptional repressor ZEB offers an additional concept of CD4 gene regulation in T cells.

Animals↗
PubMed1999

Impact of ELISA and immunoblot as diagnostic tools one year after eradication of Helicobacter pylori in a multicentre treatment study.

The performance of serological tests for Helicobacter pylori infections is hampered by the persistence of antibodies after eradication therapy or spontaneous healing. Detection of different antigens or immunoglobulin classes might have an impact on the validity of serodiagnosis. The aim of this study was to assess the decrease in IgA and IgG antibody levels after eradication of H. pylori. Serum samples of 242 patients with active duodenal ulcer were tested with the ELISA and the immunoblot (IB) techniques for H. pylori-specific IgA and IgG antibodies before therapy and 1 year after successful eradication. From a total of 81 patients paired sera were available. At the end of the follow-up period ELISA antibody titres from the IgA class had decreased from a mean value of 6.69 to 4.26 units (P = 0.0001), and IgG class antibody titres from a mean value of 21.9 to 12.1 units (P = 0.0001). Regarding seroreversion, from 34 initially IgA positive sera 16 (47%), and from 74 IgG positive sera 18 (24%), had definitively reverted to 'negative'. One year after eradication, when tested with the immunoblot, the antibody responses against specific antigens of 37% IgA-positive sera (23/62) and 8% IgG-positive sera (6/78) reverted to 'negative', compared to a seroreversion rate of 27% of the anti-CagA IgA-positive sera (18/67) and of 9% of the anti-CagA IgG-positive sera (7/79). In conclusion, despite an overall significant decrease of H. pylori antibodies, both tests cannot be recommended for monitoring treatment success.

Adult↗
PubMed1999

[Helicobacter pylori infections and autoimmunity: the interplay in the pathogenesis of gastritis].

Recent studies suggest a significant association of Helicobacter pylori (H.p.) gastritis and antigastric autoimmunity. Sera of H.p. infected patients exhibit antigastric autoantibodies with high prevalence (over 50 percent of the cases) and with antiluminal and/or anticanalicular binding patterns on gastric mucosa. Models for the pathogenesis of this H.p. associated autoimmunity are antigenic mimicry or Th 1-induced expression of MHC class II and costimulatory molecules on gastric epithelial cells. The anticanalicular autoantibodies binding to gastric parietal cells show fine specificities for the alpha- and for the beta-subunit of the gastric H, K-ATPase, which correspond to the findings in classical autoimmune gastritis. They are significantly correlated with higher grades of corpus gastritis as well as morphologic and functional glandular atrophy of the corpus. The development of this antigastric autoimmunity apparently is a relevant pathogenic factor of the host reaction and might be crucial for the different types and outcomes of H.p. gastritis.

Autoantibodies↗