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F Hofstädter

Publications and source records attributed to F Hofstädter.

At least 37 records · Page 2Linked to original sources
PubMed2000

Evaluation of a multicentre study of synchronous application of narrowband ultraviolet B phototherapy (TL-01) and bathing in Dead Sea salt solution for psoriasis vulgaris.

The synchronous application of narrowband UVB phototherapy with 311 nm lamps (Philips TL-01) and bathing in Dead Sea salt solution was evaluated in a multicentre trial (n = 60) in outpatients suffering from psoriasis vulgaris. The study design consisted of an initial therapy phase of up to 35 treatments (three to five times a week) followed by maintenance therapy with up to 35 further applications (once or twice a week). Evaluation was performed separately for patients in according-to-protocol (ATP) (n = 280) and intention-to-treat (ITT) (n = 692) groups. An overall significant improvement of the Psoriasis Area and Severity Index (PASI) score (P < 0.05) could be shown for both groups during initial therapy with 71.4% improvement for ATP and 61% for ITT patients. The mean PASI for ATP (values for ITT in parentheses) was 17.7 (18.6) at baseline, 9.5 (10.7) after 20 applications and 5.2 (7.4) at the end of initial therapy. On average, ATP patients received 3.9 (3.5) applications per week with a cumulative irradiation dose of 19.5 J cm-2 (16.2 J cm-2). The most frequent side-effect was erythema, observed in 8.7% of the patients. Subjective evaluation of the therapy by the patients (n = 168) was excellent. Seventy-nine per cent of patients preferred the new treatment strategy in comparison with other previous therapies and 88% regarded this therapy as pleasant and comfortable. In conclusion, we could demonstrate a significant effect of therapy in both the ATP and the ITT groups for this new treatment system which imitates, as far as possible, the Dead Sea climatic conditions, with no severe side-effects and a high acceptance by the patients.

Adolescent↗
PubMed2000

Microsatellite instability in tumor and nonneoplastic colorectal cells from hereditary non-polyposis colorectal cancer and sporadic high microsatellite-instable tumor patients.

Genetic alterations such as loss of heterozygosity (LOH) and microsatellite instability (MSI) have been frequently studied in various tumor types. Genetic heterogeneity of nonneoplastic cells has not yet been sufficiently investigated. However, genomic instability in normal cells could be a potentially important issue, in particular when these cells are used as reference in LOH and MSI analyses of tumor samples. In order to investigate possible genetic abnormalities in normal colorectal cells of tumor patients, MSI analyses of normal colonic mucosa were performed. Up to 15 different laser-microdissected normal regions containing 50-150 cells were investigated in each of 15 individual microsatellite-stable, sporadic high microsatellite-instable (MSI-H) and hereditary non-polyposis coli cancer (HNPCC) colorectal cancer patients. Frequent MSI and heterogeneity in the MSI pattern were found both in normal and tumor cells from 10 HNPCC and sporadic MSI-H tumor patients whose tumors had defect mismatch repair protein expressions. This observation shows that MSI can also occur in nonneoplastic cells which has to be considered in MSI analyses for molecular HNPCC screening. In addition, considerable genetic heterogeneity was detected in all MSI-H (sporadic and HNPCC) tumors when analyzing five different regions with less than 150 cells, respectively. These differences were not detectable in larger tumor regions containing about 10,000 cells. Thus, heterogeneity of the MSI pattern (e.g. intratumoral MSI) is an important feature of tumors with the MSI-H phenotype.

Cell Separation↗
PubMed1999

Multiple mutation analyses in single tumor cells with improved whole genome amplification.

Combining whole genome amplification (WGA) methods with novel laser-based microdissection techniques has made it possible to exploit recent progress in molecular knowledge of cancer development and progression. However, WGA of one or a few cells has not yet been optimized and systematically evaluated for samples routinely processed in tumor pathology. We therefore studied the value of established WGA protocols in comparison to an improved PEP (I-PEP) PCR method in defined numbers of flow-sorted and microdissected tumor cells obtained both from frozen as well as formalin-fixed and paraffin-embedded tissue sections. In addition, the feasibility of I-PEP-PCR for mutation analysis was tested using clusters of 50-100 unfixed tumor cells obtained by touch preparation of ten breast carcinomas by conventional sequencing of exon 7 and 8 of the p53 gene. Finally, immunocytochemically stained microdissected single disseminated tumor cells from bone marrow aspirates were investigated with respect to mutations in codon 12 of Ki-ras by restriction fragment length polymorphism (RFLP)-PCR after I-PEP-PCR. The modified I-PEP-PCR protocol was superior to the original PEP-PCR and DOP-PCR protocols concerning amplification of DNA from one cell (efficiency rate I-PEP-PCR 40% versus PEP-PCR 15% and DOP-PCR 30%) and five cells (efficiency rate I-PEP-PCR 100% versus PEP-PCR 33% and DOP-PCR 20%). Preamplification by I-PEP allowed 100% sequence accuracy in > 4000 sequenced base pairs and Ki-ras mutation detection in isolated single disseminated tumor cells. For reliable microsatellite analysis of I-PEP-preamplified DNA, at least 10 unfixed cells from fluorescence-activated cell sorting, 10 cells from frozen tissue, or at least 30 cells from formalin-fixed and paraffin-embedded tissue sections were required. Thus, I-PEP-PCR allowed multiple reliable microsatellite analyses suited for microsatellite instability and losses of heterozygosity and mutation analysis even at the single cell level, rendering this technique a powerful new tool for molecular analyses in diagnostic and experimental tumor pathology.

Bone Marrow Neoplasms↗
PubMed1999

Photosensitization of human skin cell lines by ATMPn (9-acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene) in vitro: mechanism of action.

9-Acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn) is a promising new photosensitizer characterized by high absorption around 640 nm and high singlet oxygen yield. To study the mechanism of action in vitro we have investigated uptake, intracellular localization, cell survival and ultrastructural changes following photodynamic treatment in human cell lines derived from the skin (SCL1 and SCL2, squamous cell carcinoma; HaCaT keratinocytes; N1 fibroblasts). Using flow cytometry we have determined the cellular fluorescence as a marker for the uptake of ATMPn after incubation for 60 min. Co-staining with ATMPn and fluorescent dyes specific for cell organelles reveals an intracellular localization of ATMPn in lysosomes. Following irradiation using an incoherent light source (580-740 nm) and a light fluence of 24 J cm-2, phototoxicity is determined by means of the 3-4.5 dimethylthiazol-2,5 diphenyl tetrazolium bromide (MTT) assay. For all cell lines ATMPn concentrations above 15 nM yield a significant phototoxic effect. The 50% effective concentration, EC50, for SCL1 cells is 11.2 +/- 2.9 nM ATMPn. ATMPn uptake and phototoxicity are more effective for HaCaT and SCL1 as compared to SCL2 and N1 cells. Growth curves confirmed the results of the MTT assay. Because of the high lysosomal accumulation of ATMPn, already low photosensitizer concentrations without dark toxicity yield a high photodynamic effect. Immunofluorescence and electron microscopy reveal damage to tonofilaments, plasma membrane and mitochondria, indicating a mechanism unrelated to apoptosis. A dose yielding complete cell killing, as needed for oncological indications, might lead to necrosis, whereas lower sub-lethal doses result in induction of apoptosis.

Cell Line↗
PubMed1999

Immunocytology improves prognostic impact of peritoneal tumour cell detection compared to conventional cytology in gastric cancer.

AIMS: Studies on the value of peritoneal tumour cell dissemination for prognosis in gastric cancer using various methods to detect tumour cells have produced conflicting conclusions. We studied the incidence and prognostic relevance of microscopic intraperitoneal tumour cell dissemination in gastric cancer, comparing conventional and immunocytological detection. METHODS: Peritoneal wash-outs of 111 consecutive gastric patients without overt peritoneal carcinomatosis, including 75 curatively resected patients, were studied. Sixty patients with benign disorders served as controls. 100 ml of warm NaCl 0.9% was instilled intraoperatively and 20 ml was reaspirated. The specimens were stained peri-operatively with H&E. In the last 47 patients (30 of whom were curatively resected) additional immunostaining with the HEA-125 antibody was performed. The results of cytology were correlated with the TNM categories and with post-operative follow-up. RESULTS: Of the patients, 42.3% and 48.9% were positive when conventional and immunocytological staining were employed, respectively. Conventional cytology was significantly associated with the pT and M categories. Immunocytology was significantly associated with the pT, pN and M caterogies. In four of 30 curatively resected patients (13.3%), the results of conventional and immunocytology were different. Three patients with positive immunocytology but negative conventional cytology died during follow-up (median follow-up 45.3 months), whereas one patient with positive conventional but negative immunocytology is still alive. In an univariate analysis 4 years post-surgery, positive immunocytology was significantly associated with an unfavourable prognosis in patients with curatively resected gastric cancer. While only 28.6% (six of 21) of the patients with negative immunocytology had died, this proportion increased to 77.8% (seven of nine) with positive immunocytology (P=0.018). The mean survival of negative vs positive patients amounted to 1205+/-91 vs 772+/-147 days (P=0.007). In contrast, in conventional cytology we found no significantly different survival time between negative and positive patients. CONCLUSIONS: Immunocytology seems to be superior to conventional cytology and should be preferred.

Case-Control Studies↗
PubMed1999

[Aspirin suppresses microsatellite instability].

Nonsteroidal anti-inflammatory drugs (NSAIDs) exhibit cancer preventive effects and have been shown to induce regression of adenomas in FAP patients. In order to elucidate the probable underlying mechanism, the effect of NSAIDs on mismatch repair related microsatellite instability was investigated. Six colorectal cancer cell lines all but one deficient for human mismatch repair (MMR) genes were examined for microsatellite instability (MSI) prior and after treatment with Aspirin or Sulindac. For rapid in vitro analysis of MSI a microcloning assay was developed by combining Laser microdissection and random (PEP-) PCR prior to specific MSI-PCR. Effects of NSAIDs on cell cycle and apoptosis were systematically investigated by using flow cytometry and cell-sorting. MSI frequency in cells deficient of MMR genes (hMSH2, hMLH1, hMSH6) was markedly reduced after long-term (> 10 weeks) NSAID treatment. This effect was reversible, time- and concentration dependent. However, in the hPMS2 deficient endometrial cancer cell line (HEC-1-A) the MSI phenotype kept unchanged. According to cell sorting, non-apoptotic cells were stable and apoptotic cells were unstable. These results suggest that aspirin/sulindac induces a genetic selection for microsatellite stability in a subset of MMR-deficient cells and may thus provide an effective prophylactic therapy for HNPCC related colorectal carcinomas.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Aspirin suppresses the mutator phenotype associated with hereditary nonpolyposis colorectal cancer by genetic selection.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are well-known cancer preventives, which have been largely attributed to their antiproliferative and apoptosis-inducing activities. In this study, we show that microsatellite instability (MSI) in colorectal cancer cells deficient for a subset of the human mismatch repair (MMR) genes (hMLH1, hMSH2, and hMSH6), is markedly reduced during exposure to aspirin or sulindac [or Clinoril, which is chemically related to indomethacin (Indocin)]. This effect was reversible, time and concentration dependent, and appeared independent of proliferation rate and cyclooxygenase function. In contrast, the MSI phenotype of a hPMS2-deficient endometrial cancer cell line was unaffected by aspirin/sulindac. We show that the MSI reduction in the susceptible MMR-deficient cells was confined to nonapoptotic cells, whereas apoptotic cells remained unstable and were eliminated from the growing population. These results suggest that aspirin/sulindac induces a genetic selection for microsatellite stability in a subset of MMR-deficient cells and may provide an effective prophylactic therapy for hereditary nonpolyposis colorectal cancer kindreds where alteration of the hMSH2 and hMLH1 genes are associated with the majority of cancer susceptibility cases.

Adaptor Proteins, Signal Transducing↗
PubMed1998

A soluble form of CD137 (ILA/4-1BB), a member of the TNF receptor family, is released by activated lymphocytes and is detectable in sera of patients with rheumatoid arthritis.

CD137 (ILA/4-1BB) is a member of the tumor necrosis factor receptor family and regulates activation, proliferation and programmed cell death in T lymphocytes. Here we show the existence of a soluble form of CD137 (sCD137) of 16 kDa. sCD137 is released by activated lymphocytes, and in contrast to membrane-bound CD137, expression of sCD137 seems to be restricted to lymphocytes. sCD137 is generated by alternative splicing and two splice variants were identified. sCD137 is present at low levels in sera of some healthy donors (5/12; mean = 0.18 ng/ml) and is significantly enhanced in sera of patients with rheumatoid arthritis (12/12; mean = 3.58 ng/ml).

Antigens, CD↗
PubMed1998

[Molecular cancer disposition diagnosis exemplified by colorectal carcinoma. What is the contribution of pathology?].

During the last few years, the molecular basis of several cancer predisposition syndromes has been discovered which offers new tools for cancer prevention and early detection. This will be demonstrated in one of the most frequent hereditary cancer syndromes, namely the hereditary nonpolyposis colorectal cancer (HNPCC) which accounts for about 5% to 8% of CRC. Thereby, families with exclusively CRC (Lynch type I syndrome) and those with extracolonic cancers especially of endometrium, stomach, small bowel and upper urinary tract (Lynch type II syndrome) can be discriminated. At the molecular level, HNPCC is caused by germline mutations in one of the mismatch repair genes (hMSH2, hMLH1, hMSH6, hPMS2). Thus, nucleotide mispairings occurring particularly within simple repetitive genomic sequences (microsatellites) during replication are no longer be repaired properly and can be demonstrated by PCR as so-called microsatellite instability (MSI). Since more than 90% of HNPCC associated and only about 15% of sporadic CRC show MSI, this test is a useful tool for HNPCC screening. In case of a negative result HNPCC is highly unlikely. In positive cases (with > or = 2 out of 5 unstable defined microsatellite markers) the definite molecular diagnosis can only be obtained by sequencing the mismatch repair genes from the patient's blood or normal DNA. As immunohistochemistry reveals loss of hMSH2 or hMLH1 expression in most MSI positive CRC, these data provide useful information for the sequencing strategy. Molecular tumor screening by MSI test and immunohistochemistry is recommended in patients i.) with a positive family history (acc. to the Amsterdam criteria), ii.) suffering from multiple HNPCC related carcinomas, iii.) with HNPCC related cancer before 45 ys of age, and iv.) with right-sided CRC exhibiting medullary, signet-ring or mucinous differentiation. Finally, these tests as well as genetic counseling and treatment of the patient need to be done by an interdisciplinary approach. Thereby, the pathologist can substantially contribute to identify HNPCC related carcinomas either by clinical or morphological criteria and to initiate the molecular screening test.

Cell Transformation, Neoplastic↗
PubMed1998

Gap junctions in health and disease.

An international symposium was held on gap junctions in health and disease in Regensburg, Germany, gathering together a panel of international scientists who discussed normal functions of gap junctions and their contribution to a variety of human diseases. The emphasis was on strategies and models for a better understanding of gap junction-mediated cell-to-cell communication in a variety of tissues, including null mutations of gap junction genes in recombinant transgenic mice. The topics varied from the normal function of cardiac gap junctions and its contribution to cardiac dysfunction up to the recently discovered point mutations of a gap junction gene encoding the gap junction protein connexin32 in Charcot-Marie-Tooth syndrome of the X1 type. A perspective of the future development of gap junction research and its contribution to unravelling pathophysiological mechanisms of human diseases was given by M.V.L. Bennett.

Animals↗
PubMed1998

Coexistent thyroiditis is associated with lower tumour stage in thyroid carcinoma.

BACKGROUND: Microsatellite instability (MSI) is a new mechanism described in carcinogenesis of several tumours and seems to predispose for cancer in some chronic inflammatory diseases. As thyroiditis is thought to be both the cause and the consequence of thyroid carcinoma, it was the aim of this retrospective study to investigate the epidemiology and the influence of a coexistent thyroiditis on prognosis and clinicopathological parameters in an iodine-deficient area. METHODS: The grade of lymphocytic infiltration (LI) of 153 thyroid carcinomas was determined in paraffin-embedded tissues: G0 = no LI, G1 = peritumoral LI, G2 = peritumoral LI with follicle, G3 = diffuse LI. A non-radioactive PCR-based screening method was used for detection of MSI. RESULTS: Twenty-seven (17.7%) out of 153 carcinomas were accompanied by thyroiditis (G1, 16; G2, 5; G3, 6). Ten cases fulfilled the criteria necessary for diagnosing Hashimoto's thyroiditis. Nine out of 10 (90%) Hashimoto's cases and 16 out of 17 (94%) other thyroiditis cases were associated with a significantly (chi2 < 0.01) lower pT stage (pT1, pT2) than cases without thyroiditis. No statistical association was found by comparing multifocality or sclerosing variants with the grade of lymphocytic infiltration. MSI was detected neither in patients with severe inflammation nor in the absence of thyroiditis. CONCLUSIONS: MSI does not seem to play a role in the pathogenesis of thyroid carcinoma. Coexistent thyroiditis is associated with a lower pT stage and thus could be an indicator of a better prognosis.

Adult↗
PubMed1997

Analysis of cell cycle-related Ki-67 and p120 expression by flow cytometric BrdUrd-Hoechst/7AAD and immunolabeling technique.

Flow cytometric multiparameter analysis of two proliferation associated antigens, Ki-67 and p120, was combined with cell cycle kinetic analysis, achieved by continuous labeling with 5-Bromodeoxyuridine (BrdUrd), followed by staining with Hoechst 33258 and 7-Aminoactinomycin D (7AAD). Exponential and plateau phase monolayer cultures of the human bladder carcinoma cell line J82 were examined. Resting cells, characterized by their absent BrdUrd incorporation, showed no reactivity with the MIB1 antibody, which was used for the detection of the Ki-67 antigen. Proliferating cells revealed a cell cycle phase dependent Ki-67 staining intensity, which was partially related to the time period spent in G1 after mitosis. In contrast to the Ki-67 antigen expression, no decrease in p120 immunofluorescence staining intensity of non-cycling cells could be observed. We could demonstrate that a dissection of the history of cell replication, obtained by the BrdUrd/Hoechst technique combined with a simultaneous immunofluorescence staining reveals detailed information, on a single cell level, about time dependent expression of proliferation associated antigens in all cell cycle compartments.

Antigens, Neoplasm↗
PubMed1997

Indocyanine green: intracellular uptake and phototherapeutic effects in vitro.

Indocyanine green (ICG; absorption peak in human plasma 805 nm) was investigated for ICG-mediated phototherapy in vitro. The cellular uptake of ICG (1 microM-50 microM) into HaCaT keratinocytes after an incubation period of 24 h increased up to an intracellular ICG concentration of 12.1 +/- 1.3 nmol per 10(6) cells. To examine dose dependent phototoxic effects in vitro, keratinocytes were incubated with 0 microM-50 microM ICG for 24 h and irradiated by a diode laser (805 nm) with different energy densities (0, 12, 24, 48 J cm-2). All applied ICG concentrations except for 5 microM yielded a cell killing effect in combination with irradiation depending significantly on ICG concentration and light dose. Cell viability for dark control and cells incubated with 50 microM ICG and irradiated with 48 J cm-2 was 0.82 +/- 0.15 and 0.07 +/- 0.02, respectively. Sodium azide (100 mM), a quencher of reactive oxygen species, inhibited significantly the cell killing using 50 microM ICG and 24 J cm-2. Taken together, photoactivation of ICG by irradiation with a diode laser was shown to induce effectively cell killing of HaCaT keratinocytes. Moreover, this effect was inhibited by sodium azide, thus irradiation of ICG might induce a photodynamic reaction.

Antineoplastic Agents↗
PubMed1997

Pigmented peripheral nerve sheath tumor of the oral cavity with expression of AP-2 beta and c-RET: a case report.

Pigmented peripheral nerve sheath tumor of the oral cavity is a rare lesion and may be difficult to distinguish clinically from true melanocytic tumors. We report a case of pigmented peripheral nerve sheath tumor with a high degree of melanocytic differentiation and describe its histologic and ultrastructural features. Immunohistochemistry and polymerase chain reaction findings support the neural crest origin of the tumor. The clinical course of our case indicates that local recurrence may be a significant problem in pigmented peripheral nerve sheath tumor.

Adult↗
PubMed1997

Characteristics of multicellular spheroids formed by primary cultures of human thyroid tumor cells.

Features of multicellular tumor spheroids (MCTS) differed depending on their types of cells. MCTS formed by 4000 human thyroid primary culture epithelial tumor cells displayed diameters between 0.31 and 0.33 mm within 2 days regardless of the stage of malignancy of the originating tumors. Their cellular composition reflected that of the originating tumor in regard to DNA content and the expression of cytokeratin, vimentin, as well as thyroglobulin. During the following 3 weeks, their sizes increased up to diameters of 0.42 mm when their cells had been derived from carcinomas, and MCTS originating from adenomas stopped growing within the next 2 days. After 8 days of incubation, proliferating cells were only found in carcinoma MCTS. The cells were randomly distributed over the total volume of the spheroids, which displayed irregular cell arrangements but not concentric cell layers and did not form necrotic centers.

Antigens, Neoplasm↗
PubMed1996

Cell-type-specific response to shock waves of suspended or pelleted cells as analysed by flow cytometry or electrical cell volume determination.

Shock-wave-induced cell damage of suspended or pelleted bladder cancer cells was analysed with the flow cytometric propidium iodide (PI)/fluorescein diacetate assay, and electrical volume determination using the CASY 1 analyser system and growth curves. The CASY system revealed a smaller fraction of suspended RT4 cells with impaired membrane integrity than the flow cytometric assay. No differences were found for pelleted RT4 cells and suspended J82 cells. The discrepancies of the two viability assays indicated a different response of the cell membrane to shock waves which was dependent on the exposure system and the cell type. Growth curves indicated delayed cell death for suspended RT4 cells and exclusively immediate cell death for pelleted RT4 cells and suspended J82 cells. PI positive suspended RT4 cells were morphologically intact while pelleted RT4 cells and suspended J82 cells were mainly disrupted. From these data it can be concluded that intracellular or membrane alterations seem to be correlated with the occurrence of cavitational effects while cell disruption can likewise occur by the direct impact of the shock wave.

Carcinoma, Transitional Cell↗