Biomedical subjects

F Hofstädter

Publications and source records attributed to F Hofstädter.

At least 19 recordsLinked to original sources

PubMed1996

Detection of early bladder cancer by 5-aminolevulinic acid induced porphyrin fluorescence.

PURPOSE: We determined whether the sensitivity of detecting dysplasia or early bladder cancer can be improved by 5-aminolevulinic acid induced porphyrin fluorescence. MATERIALS AND METHODS: A 3% 5-aminolevulinic acid solution was instilled intravesically before cystoscopy in 104 patients. The 5-aminolevulinic acid induced porphyrin fluorescence was excited by violet light from a krypton ion laser (wavelength 406.7 nm.). RESULTS: The sensitivity of the fluorescence cystoscopy (96.9%) was significantly (p < 0.0001) greater than that of white light cystoscopy (72.7%). There was no impact on specificity. CONCLUSIONS: Due to the high sensitivity of the procedure fluorescence guided biopsies are recommended instead of random biopsies.

Administration, Intravesical↗

PubMed1995

Characterization of sugar receptor expression by neoglycoproteins in oral and oropharyngeal squamous cell carcinomas.

Recognition of the carbohydrate part of cellular glycoconjugates by sugar receptors like lectins may contribute to biosignaling and interactions between normal and transformed cells. Such recognitions may be essential for establishing phenotypic characteristics in neoplastic cells, including metastasis-associated properties. To evaluate various glycoconjugates in tumor diagnosis and clinical therapy, a panel of 18 biotinylated neoglycoproteins was prepared. This included conjugates of a histochemically inert carrier protein and crucial sugar moieties such as D-glucuronic acid, alpha- and beta-N-acetyl-galactosamine, beta-N-acetyl-glucosamine, melibiose, lactose, maltose, cellobiose, mannose, mannose-6-phosphate, fucose, rhamnose, and xylose. In so doing the diazo derivative of the respective p-aminophenyl glycosides was coupled with galactose, beta-N-acetyl-galactosamine or beta-N-acetyl-glucosamine via an epoxy group-containing aliphatic spacer. Other glycoconjugates used were the proteoglycan heparin and the sulfated fucan fucoidan. Labeling was effected with cyanogen bromide activation and aminoalkylation for specific detection of endogeneous sugar receptors, especially lectins. Tissues studied were paraformaldehyde-fixed, paraffin-embedded surgical biopsies from patients with different stages of squamous cell carcinomas (SCCs) of the oral cavity (n = 16) and oropharynx (n = 17), including three lymph node metastases from oropharyngeal primary tumors. Semiquantitative binding differences of probes to tumor stages were evaluated statistically by the Mann-Whitney U-Wilcoxon rank sum W test. Specific binding of a probe to cytoplasmic and nuclear structures was detected with apparent quantitative differences. Overall, the cytoplasmic compartment revealed a higher intensity of histochemical reaction than did nuclear structures, indicating a comparatively higher density of specific carbohydrate receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Detection of microsatellite instability in human colorectal carcinomas using a non-radioactive PCR-based screening technique.

The aim of the present study was to establish a rapid, non-radioactive screening method for the detection of microsatellite instability (MIN). MIN is the primary characteristic of the mutator phenotype in tumours constituting hereditary non-polyposis colon cancers (HNPCC). We investigated 30 patients suffering from colorectal cancer using a non-radioactive PCR-based technique. MIN was present in 7 of 30 (23%) of the cases. There was a statistically significant correlation between MIN and localization of the tumour. Five of 7 (72%) tumours with MIN but only 4 of 23 (17%) tumours without MIN were localized in the proximal colon (P < 0.01). There was a tendency to higher MIN frequency in tumours of patients with familial clustering of cancers. However, this was statistically not significant (P > 0.05). In addition, no correlation between MIN and tumour grade and stage was found. For the investigations in the present study we used a non-radioactive PCR-based method followed by denaturating polyacrylamide gel electrophoresis and silver staining. This method is highly sensitive and reproducible. Thus, PCR-based analysis using a non-radioactive staining technique represents a comprehensive tool for MIN screening in diagnostic pathology.

Adult↗

PubMed1995

Cell proliferation assessment in oncology.

A review of the current knowledge on cell cycle control and the techniques used to assess proliferation of normal and neoplastic cells was the focus of a workshop in Regensburg, Germany, held under the joint auspices of the Graduiertenkolleg: Therapieforschung Onkologie and the Committee on AgNOR Quantification. An overview of the recently discovered group of cyclins and their specific kinases, and of other proliferation-associated antigens, such as Ki67, PCNA and topoiseromase II alpha, was given. The topics continued with a reappraisal of modern imaging and flow-cytometric techniques. An update of the relation of AgNORs to cellular proliferation and differentiation was the link to presentations on clinical data, problems and strategies for standardization, as well as guidelines to establish the prognostic value of marker molecules. These lectures were supported by posters. Bringing together researchers from life sciences, technically oriented workers, pathologists, and clinicians resulted in a lively and constructive discussion, which is briefly summarized in the Concluding remarks.

Cell Cycle↗

PubMed1995

Flow cytometric analysis of cell suspensions exposed to shock waves in the presence of the radical sensitive dye hydroethidine.

The occurrence of intracellularly and extracellularly generated free radicals during shock wave exposure on an experimental Siemens lithotripter was tested with the radical sensitive dyes hydroethidine and dichlorofluorescin (DCFH). DCFH, a nonfluorescent compound, is oxidised to dichlorfluorescein (DCF) by hydrogen peroxide in the presence of peroxidase. DCF green fluorescence intensity was used for fluorescence spectrometric measurement of hydrogen peroxide generated during shock-wave treatment of cell-free dye solutions. The fluorescence intensity of ethidium, the oxidised form of hydroethidine, was used for the flow-cytometric measurement of intracellular oxidising reagents present in RT4 tumour cells during shock-wave exposure. Changes in membrane permeability, which influence the intracellular content of ethidium, were controlled by counterstaining the cells with propidium iodide, an indicator for membrane integrity. We observed no increase in intracellular ethidium fluorescence intensity after shock-wave treatment of single cell suspensions and therefore no indication for shock-wave-induced intracellular free radicals.

Carcinoma, Papillary↗

PubMed1995

Blood group phenotype determines lectin-mediated adhesion of Pseudomonas aeruginosa to human outer ear canal epithelium.

Pseudomonas aeruginosa is the most frequent bacterial pathogen causing acute diffuse otitis externa. In a recent prospective phase II study we demonstrated that lectin-mediated bacterial adhesion can be blocked by receptor-analogue carbohydrates in patients suffering from Pseudomonas aeruginosa-induced acute otitis externa. In this investigation, human ABO blood group antigens were analysed on outer ear canal epithelial cells with standard routine histological procedures by monoclonal antibodies for the blood groups A and B, and with Ulex europaeus I lectin for the blood group O, respectively. In all cases (n = 20) the blood groups could be shown immunohistologically. P. aeruginosa-specific adhesion and inhibition assays were performed in the presence of N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), D-mannose and A-like substance. Outer ear canal tissue sections were incubated with P. aeruginosa (strain PA 60), presenting lectin-specificity for GalNAc. Sections from patients presenting with blood group A were closely settled with bacteria in the presence of non-specific GlcNAc, D-mannose and PBS however, GalNAc and A-like substance inhibited the microbial adhesion. Amongst others, P. aeruginosa present adhesion molecules (lectins) with specificity for GalNAc. Thus, the correlation between blood group A phenotype and P. aeruginosa-induced acute diffuse otitis externa was investigated. Statistical evaluation proved a highly significant association. These data support the hypothesis that P. aeruginosa lectins with GalNAc specificity apparently adhere to GalNAc moieties, representing the terminal blood group A-determinant and further indicate that patients presenting with blood group A may have a genetic disposition for this form of otitis externa.

ABO Blood-Group System↗

PubMed1995

Human follicular and papillary thyroid carcinoma cells interact differently with human venous endothelial cells.

Follicular thyroid carcinomas (FTC) characteristically spread via blood vessels, while papillary thyroid carcinomas (PTC) predominantly metastasize to lymph nodes. This different behavior of cancer cells originating from one organ was investigated by layering multicellular tumor spheroids (MCTS) consisting of various kinds of human thyroid cells onto confluent monolayers of human venous endothelial cells (HEC). The MCTS and HEC were cocultured in an incubation chamber fixed under a microscope, and the behavior of the cells was investigated. In this way significant differences between FTC, PTC, and follicular adenoma cells (FTA) were observed regarding their in vitro behavior upon interaction with HEC. FTC cells required 20 min for adhesion and another hour until they migrated out of a spheroid, whereas PTC- and FTA-MCTS were adhesive after 2 h or later, and their cells did not start migration until 5 h of incubation. Furthermore, one FTC-spheroid triggered about 100 endothelial cells to enter the replication cycle, while no spheroid consisting of either PTC or FTA cells induced more than 20 endothelial cells to start proliferation. During these processes, the cells of the MCTS and the endothelial cells contacted each other directly and remained viable. The results show that FTC cells interact faster and more intensively with human endothelial cells than PTC and FTA cells. Thus the study suggests that an enhanced capability of the FTC cells to interact with venous endothelial cells might favor the clinically observed hematogenous spreading of follicular thyroid carcinomas.

Adenocarcinoma, Follicular↗

PubMed1995

Cloning and characterization of a second AP-2 transcription factor: AP-2 beta.

AP-2 has been characterized previously as a unique 52 x 10(3) M(r) transcription activator encoded by a single gene that is expressed in a restricted pattern during embryonic morphogenesis of the peripheral nervous system, face, skin and nephric tissues. Here we report the isolation of genomic and cDNA clones encoding for a second AP-2 related transcription factor, designated AP-2 beta. AP-2 beta binds specifically to a series of well-characterized AP-2 binding sites, consensus to the sequence G/CCCN3GGC, and transactivates transcription from a reporter plasmid under the control of an AP-2-dependent promoter. A C-terminal domain known to mediate homodimerization of the previously cloned AP-2 alpha transcription activator is highly conserved and sufficient to mediate interaction between the two proteins. Northern blot and in situ hybridizations revealed that the two genes are expressed in murine embryos between days 9.5 and 19.5 p.c. Coexpression of both mRNAs was detected in many tissues at day 13.5 and 15.5 of embryogenesis but some regions of the developing brain and face including the primordium of midbrain and the facial mesenchyme differed in their expression pattern of AP-2 genes. AP-2 alpha and AP-2 beta signals in the central and peripheral nervous system overlapped with regions of developing sensory neurons. In adult tissues AP-2 alpha expression was found mainly in the skin, eye and prostate and AP-2 beta expression in the kidney. In summary, our analyses of embryonic and adult mice demonstrate that two different AP-2 transcription factors are specifically expressed during differentiation of many neural, epidermal and urogenital tissues.

Amino Acid Sequence↗

PubMed1995

[Pathology of wound healing].

In this review the morphologically defined steps of wound healing are described. Then the mechanisms of molecular regulation are discussed, which are the basis of the phases of wound healing. A main topic is the role of signal peptides in the regulation of cellular and stromal alterations during wound healing. An overview is given about the respective growth factors, their main function during wound healing and their receptors. Finally, analogies with fetal wound healing and the therapeutic modulation of wound-healing disturbances are discussed.

Animals↗

PubMed1995

[New in vitro test systems].

Experimental in vitro systems are discussed with reference to their use as models für the analysis of basal tumor-host interactions. Multiple functions of macrophages are treated and there is also a special focus on the differentiation of macrophages in vitro and the influence of cocultures with the influence of cocultures with tumour cells (monolayer, spheroids). These experiments have shown that differentiation can be suppressed by tumour cells with three-dimensional growth. These findings are of interest for (a) adoptive immunotherapy and (b) the interpretation of tumour-infiltrating macrophages. These tests are not suitable for in vitro monitoring of clinical immunotherapy.

Carcinoma, Transitional Cell↗

PubMed1994

[In vitro culture: from tissue to cell line].

This article describes how tissue culture has developed from an observing method to a powerful analytical technique for oncology and for pathological cell changes such as metabolic disorders and degenerative diseases. Standard terms are defined and basic methods are explained. Different models of in vitro culture--monolayer, three-dimensional tumor cultures, and organ cultures--are critically reviewed in respect of their significance for the interpretation of in vivo tissue. Two important recent extensions of tissue culture, serum-free cell culture and the introduction of genetic material into cells, are described.

Animals↗

PubMed1994

Induction of stress fibres and intercellular gaps in human vascular endothelium by shock-waves.

Human umbilical cords were exposed to high amplitude focussed ultrasonic pulses with focal energy densities 0.6 and 0.4 mJ mm-2. The endothelium of the exposed vessel (vein) was examined by means of confocal laser scanning microscopy and scanning electron microscopy. The degree of tissue change ranged from the induction of stress fibres and intercellular gaps to the complete detachment of endothelial cells combined with damage of the basement membrane. An increased number of stress fibres may indicate an increased vessel wall permeability. This might explain the enhanced effects in experimental tumour therapy that have been found by other authors when combining shock-waves with drugs.

Basement Membrane↗

PubMed1994

Shock wave induced endothelial damage--in situ analysis by confocal laser scanning microscopy.

For more than a decade, extracorporal shock wave lithotripsy has been a standard clinical method for the treatment of urinary stones. However, side effects that are likely to be correlated to vessel damage can often be observed using noninvasive diagnostic techniques, e.g., magnetic resonance imaging. To avoid side effects it is useful to understand the interaction between shock waves and the vascular system. In particular, this is important in view of new applications like gallstone lithothripsy. In the present study, we exposed human umbilical vessels to electromagnetically generated ultrasound shock waves to analyze subsequent alterations of their endothelial layer. Following en face preparation and fluorescent staining, the endothelium was examined in a confocal laser scanning microscope. Endothelial cells of the shock wave exposed vessels revealed permeabilization of plasma membranes and mitochondrial alterations as potentially lethal damage. An increase in the number of stress fibres may indicate functional changes possibly influencing vessel wall permeability.

Endothelium, Vascular↗

PubMed1994

A heterologous in vitro coculture system to study interaction between human bladder cancer cells and fibroblasts.

Three-dimensional multicellular spheroids of two fibroblast cell lines (WI-38 and N1) and two differently differentiated bladder carcinoma cell lines (RT4 and J82) were used for cocultures of multicellular tumor spheroids with multicellular spheroids of fibroblasts. The aim of the study was the establishment and characterization of a standardized three-dimensional model for studies of tumor cell-fibroblast interaction as one aspect of tumor-stromal cell interactions of in vivo tumor tissue. Interaction of multicellular spheroids of both fibroblast cell types was analyzed by staining with antibodies against cytokeratin, vimentin and different extracellular matrix molecules. Further, proliferation assessment and phenotypic characterization of the cocultures are presented. Interactions varied with tumor cell type and fibroblast cell type, reflecting intrinsic properties of tumor cells and fibroblasts. The coculture of tumor cells with N1 reflected the in vivo situation the closest, since invasive properties of J82 as well as noninvasive properties of RT4 were characteristics seen in coculture.

Cell Communication↗

PubMed1994

Fluorescence photodetection of neoplastic urothelial lesions following intravesical instillation of 5-aminolevulinic acid.

OBJECTIVES: Tiny papillary tumors and flat urothelial lesions such as dysplasia or carcinoma in situ can easily be missed during routine cystoscopy. Various methods for in vivo detection of fluorescing agents (preferentially localized in malignant tissue) have been developed. Most of them are based on systemically administered synthetic porphyrin compounds and require sensitive detection devices and image processing units for fluorescence visualization. The usefulness of intracellularly accumulated endogenous protoporphyrin IX (PPIX), induced by 5-aminolevulinic acid (ALA), for diagnosis of early bladder cancer and the correlation with cystoscopic, microscopic, and fluorescence findings was investigated. METHODS: ALA was instilled intravesically in 68 patients, followed by fluorescence cystoscopy with violet light from a krypton ion laser that produced fluorescence excitation. There were 299 biopsies obtained from fluorescing and nonfluorescing areas of the bladder. RESULTS: ALA-induced fluorescence could be easily observed with the naked eye during cystoscopy under violet light illumination. All tumor lesions were sharply marked with brightly shining red fluorescence. Correlation of fluorescence and microscopic findings gave a sensitivity of 100% and a specificity of 68.5%. There were 26 malignant or precancerous lesions that were missed during routine cystoscopy but were detected only by ALA-induced fluorescence. CONCLUSIONS: Labeling of urothelial lesions by PPIX fluorescence induced by intravesically instilled ALA seems to be a promising diagnostic procedure for malignant lesions that are difficult to visualize with standard cystoscopy.

Administration, Intravesical↗

PubMed1994

Intravesical instillation of 5-aminolevulinic acid: the fluorescent metabolite is limited to urothelial cells.

OBJECTIVES: For photodynamic therapy 5-aminolevulinic acid is an attractive compound, since it is a physiologic endogenous substance, and its application in excess results in the accumulation of the metabolite protoporphyrin IX, a very effective photosensitizer. The topical application of 5-aminolevulinic acid in the urinary bladder led to pronounced fluorescence in neoplasias when excited with violet laser light during cystoscopy. The aim of this study was the determination of the transmural distribution of protoporphyrin IX in order to estimate potential efficacy and side effects of a therapeutic application of 5-aminolevulinic acid. METHODS: 5-Aminolevulinic acid was instilled prior to cystoscopy and biopsies were taken of lesions that were either fluorescing or nonfluorescing. Fluorescence distribution was analyzed by fluorescence microscopy on cryostat sections prepared from 72 biopsy specimens. In addition, multicellular spheroids grown from tumor cells and fibroblasts were exposed to 5-aminolevulinic acid and analyzed accordingly. RESULTS: Biopsy preparations showed that the fluorescence of protoporphyrin IX was limited to normal and neoplastic urothelial cells. Clinical findings were supported by the in vitro data, which showed negative protoporphyrin IX fluorescence in fibroblasts. CONCLUSIONS: Thus, 5-aminolevulinic acid might be superior in selective accumulation to conventional sensitizers known to localize also in endothelial cells of the tumor stroma. The data appear to hold great promise for 5-aminolevulinic acid in photodynamic diagnosis and therapy in bladder cancer, as phototoxicity will be limited to mucosal lesions. Bladder shrinkage due to photodamage of subepithelial structures even in case of high light doses is not expected.

Administration, Intravesical↗

PubMed1994

AgNOR quantification with special reference to staining patterns.

Silver staining of nucleolar organizer regions (AgNORs) is now widely used as a marker of malignancy in tumor pathology. Standardization of the AgNOR technique has thereby been shown to be of central importance. Basically, three types of AgNOR evaluation have been used: the counting method, image analysis and pattern recognition. Today, image analytical determination of AgNOR area per nucleus is considered to be the state of art method of AgNOR evaluation. In contrast, counting of every single AgNOR dot is laborious and less reproducible. For routine purposes, however, a rapid evaluation of AgNORs would be desirable. In order to elucidate the value of AgNOR distribution patterns systematic in vitro studies using four different urothelial cell lines (HU609, RT4, J82, MGHU1) were performed. AgNOR number (NORN) and AgNOR area (NORA) were closely related to the population doubling time (PDT) and increased during transition from G0/G1 to S/G2 cell cycle phase. In addition, both parameters were significantly elevated in the polyploid RT4 cell line. In contrast, number and area of AgNOR cluster (aggregates of at least two AgNOR dots) were less significantly correlated to PDT. Formation of large AgNOR clusters (maximum diameter over 6 microns) was, however, restricted to the well differentiated cell lines (HU609, RT4) although PDT was almost identical in all 4 cell lines at exponential growth phase. Thus, NORN and NORA are not only related to cell proliferation but also to cell cycle phases and ploidy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Cycle↗

PubMed1994

[Autologous blood transfusion in tumor operations].

OBJECTIVE: The potential and limits of autologous transfusion in tumor patients are discussed according to the literature. New aspects are derived from own recent studies. DATA SOURCES AND SELECTION CRITERIA: The critical review of the German and English literature is based on a Medline and DIMDI backsearch covering the last 20 years. Own data not yet published are presented. RESULTS: Predeposit autologous blood represents an important and practical alternative to homologous transfusion also for tumor patients. Predeposit programs are limited by tumor anemia, the urgent time schedule for surgery, and the variable need for transfusions. Intraoperative autotransfusion is contraindicated in these patients. Our own studies on the presence of tumor cells in the blood shed from the surgical field during oncologic surgery confirm the concerns about a systemic spread of tumor cells after retransfusion. Further efforts aim to an elimination of contaminating tumor cells. In contrast to the literature filters for white blood cell depletion were found to fail to completely remove tumor cells. A 3 log10 retention was measured. Proliferative activity of tumor cells was completely abolished by irradiation of the blood. CONCLUSIONS: Irradiation with 50 Gy allows safe retransfusion of blood salvaged during tumor surgery. This promising possibility is now to be tested in clinical studies.

Blood Loss, Surgical↗