Search PubMed⌕ Search

Biomedical subjects

W Tilgen

Publications and source records attributed to W Tilgen.

At least 127 records · Page 7Linked to original sources
PubMed1987

Modulation of melanoma-associated antigens by monoclonal antibodies as visualized by radioimmunoelectron microscopy and radioantibody binding assay.

There is a wealth of information about monoclonal antibody (MAb) specificity and function on fixed tissues, yet little is known about formation and release of antigen-antibody complexes and their functional behavior in vivo. We analyzed the pathway of radiolabeled MAbs directed against melanoma-associated antigens by radioimmunoelectron microscopy (RIEM) on metabolically active cells of the melanoma cell lines SK-MEL-28, MeWo and Colo 38 at different time intervals. In parallel, binding and release of MAbs were investigated by the radioantibody binding assay (RBA). Both procedures gave essentially concordant results. Preferentially stable binding of immune complexes (ICs) to the cell surface after 30 and 120 min was shown for the MAb L10. Internalization was demonstrated for the MAb M.2.9.4. At the ultrastructural level, direct evidence of this phenomenon was obtained by visualization of radioactivity within the cytoplasm after 120 min. In the RBA this process was indicated by resistance of bound MAbs to acid buffer desorption. RIEM pointed to different transport mechanisms: constitutive internalization by endocytotic vesicles, or receptor-mediated endocytosis by coated vesicles. Shedding was indicated for the MAb R24 by release of the ICs from the cell membrane. It was demonstrated that stable fixation of ICs on the cell surface or modulation by internalization led to high accumulation rates, while shedding of antigen-antibody complexes resulted in a low accumulation of the MAb in tumor cells. Assuming that the potential of MAbs for clinical application is determined by the biological behavior of antigen-antibody complexes, these methods are suitable for demonstration of antigenic modulation by MAbs and eventually enable us to predict the localization, penetration and distribution pattern of individual MAbs in the melanoma patient.

Antibodies, Monoclonal↗
PubMed1986

[False-positive results in the detection of anti-LAV/HTLV-III antibodies by enzyme immunoassay].

Two groups of sera were investigated with two different enzyme immunoassays for the detection of anti-LAV/HTLV-III-antibodies: 50 sera collected from patients with lupus erythematosus and 5 sera containing anti-HLA-DR4 antibodies. Of the 50 sera of the lupus erythematosus patients, 2 were positive in each of the tests. Of the 5 sera that contained anti-HLA-DR4 antibodies, one was positive. In addition, 11 sera showed positive results after heat treatment (56 degrees C, 1 h) in one of the tests. However, all sera in this group gave negative results in the other test. The positive results could not be confirmed with the immunoblot. These findings show that one must be aware of false-positive results when the sera of certain types of patients are investigated in anti-LAV/HTLV-III enzyme immunoassays. The sera of patients with lupus erythematosus, as well as that of polytransfused persons or multiparous women, that have been sensitized with HLA-DR4 antigens; heat treatment in one test has an effect on sera.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Modes of binding and internalization of monoclonal antibodies to human melanoma cell lines.

The process of monoclonal antibody (MAb) binding to tumor cells is greatly influenced by the biology of the respective antigen. This was concluded from an analysis of binding and release of MAbs and MAb fragments to melanoma cells at different concentration levels and different temperatures. With an antigen known to be stably expressed at the cell surface (i.e., Mr 97,000 protein) rapid binding of MAbs was observed at both 0 degrees C and 37 degrees C, and this was reversed by treatment with isoosmolar acid buffer. With another group of antigens, MAb binding increased continuously up to considerable levels at 37 degrees C, but not at 0 degrees C. Concomitantly, the portion of radioactive MAb not desorbable by acid buffer treatment increased, pointing to temperature-dependent internalization. With still another group of (glycolipid) antigens, the highest MAb binding was obtained with fixed cells at 0 degrees C. In this situation MAb release was particularly rapid, thus pointing to a shedding process.

Antibodies, Monoclonal↗
PubMed1986

[Kaposi's sarcoma of the larynx].

Kaposi's sarcoma of the larynx is a rarely observed manifestation of AIDS. Possible concomitant symptoms are hoarseness up to aphonia, urge to cough or stridor. Expectoration of small parts of tissue of Kaposi's sarcoma may be an additional sign. Similar to Kaposi's sarcoma in the oral cavity Kaposi's sarcoma of the larynx is characterised by a purplish, spongy nodule. Its surface can be verrucous due to deposits of dry secretion. Local extirpation of Kaposi's sarcoma removes the laryngeal signs and symptoms.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Growth and differentiation characteristics of transformed keratinocytes from mouse and human skin in vitro and in vivo.

The altered phenotypic expression and chromosomal characteristics of mouse and human malignant keratinocyte lines have been studied in vitro and in vivo (in comparison with normal primary cultures). The cell lines exhibited different morphologic aspects that are probably more related to their respective degree of differentiation than to different stages in malignancy. Although all cell lines studied were deficient in some aspects of keratinization, certain basic structural and biochemical features were maintained, and these may serve as valid criteria for the identification of their epithelial nature. The altered expression of keratin proteins and morphologic differentiation can be modulated under in vivo growth conditions, but they cannot be reverted toward normality. Chromosomal alterations (in number and structure) occur early and are highly indicative criteria for malignancy, even though no tumor-specific aberrations have been identified. Two new approaches for evaluating characteristics of abnormal growth and differentiation in vitro, and of invasiveness in vivo, have been developed and have proved sensitive test methods for identifying malignant cells. While several abnormalities in growth and differentiation of cell lines in vitro are highly indicative of their malignant nature, the final proof that they are tumor cells still requires in vivo assay. The transplantation assay for studying cellular invasiveness not only improves the sensitivity of in vivo malignancy tests but has also proved to be a valuable model system for elucidating the modulation of differentiation by external influences.

Animals↗
PubMed1983

Localization of melanoma-associated antigen p97 in cultured human melanoma, as visualized by light and electron microscopy.

The expression of a human melanoma-associated antigen, p97, in cultured melanoma cells was investigated using a modification of the Sternberger peroxidase-antiperoxidase (PAP) technique. Explant cultures of two skin melanomas were found to consist of a mixture of cells, some positive and some negative, for the expression of p97. From two other melanomas two cell lines were newly established. All cells from these lines expressed detectable p97 over a period up to 18 months. With the cell lines and the explant cultures we have initiated an investigation of the expression of p97 at the ultrastructural level, using the PAP technique. Antigen expression was detected as a continuous, strongly stained band at the cell surface of the melanoma cells.

Antigens, Neoplasm↗
PubMed1983

Preservation of morphological, functional, and karyotypic traits during long-term culture and in vivo passage of two human skin squamous cell carcinomas.

Two cell lines (SCL-I and SCL-II) derived from squamous cell carcinomas of human skin were investigated during 4 years in culture. Both lines were tumorigenic in nude mice, and cells could be recultivated from xenografts. Growth in agar remained poor, but both cell lines developed abnormal stratified epithelial structures in organotypical cultures. The morphological and particularly ultrastructural characteristics remained typical in both cultures and xenografts. Keratinization slightly decreased, but nude mouse tumors differentiated as the original tumors, and this was reflected in keratin expression. Six major polypeptides (Mr 61,000, 57,000, 54,000, 51,000, 49,000, and 45,000) were similarly identified in both tumors and cell lines, also after animal passage, which was further substantiated by two-dimensional gel electrophoresis, but quantitative variations were found with different growth conditions. A distinct keratin cytoskeletal network was visualized in both lines by immunofluorescence, but only a few cells in SCL-II also expressed vimentin. Flow cytometry demonstrated 2c DNA stem lines for original tumors and derived lines. Early passages were hypodiploid by cytogenetic analysis of banded chromosomes. In SCL-I, a shift to tetraploidy occurred before passage 20 and remained stable throughout. In SCL-II, an incomplete shift to near tetraploidy and a stem line deviation were apparent, but later passages, nude mouse tumors, and cells recultured therefrom were hypodiploid (2c) again. Chromosome studies further revealed distinct stable marker chromosomes which showed additional structural aberrations with time in culture and after animal passage. Thus, phenotypically and genotypically, each squamous cell carcinoma and its derived cell line were distinct, and characteristics were preserved over long time periods in vitro and through in vivo passage.

Animals↗
PubMed1983

[Unilateral linear basal cell nevus].

Clinical, histopathological, electron-microscopical and cytophotometrical features of a case of linear unilateral basal cell nevus are reported. Several publications exist on basaliomas originating in a nevus verrucosus or nevus comedonicus. Our case, however, is regarded as an abortive form of the basal cell nevus syndrome due to somatic mutation. Only some few comparable cases are documented in the literature.

Basal Cell Nevus Syndrome↗
PubMed1982

Detection of a human melanoma-associated antigen, p97, in histological sections of primary human melanomas.

The unlabelled antibody technique of Sternberger was used to study the localization in histological sections of human melanoma-associated antigen p97, which is defined by a monoclonal antibody. The antigen was detected in 8 of 10 primary skin melanomas, in 6 of 7 metastatic melanomas and in 2 of 2 compound nevi. It was localized at the cell surface, the cytoplasm and the nucleus always being negative. The antigen was not seen in cells from 3 basal cell carcinomas, 1 squamous cell carcinoma, 1 leiomyosarcoma, or in samples of normal skin (including keratinocytes, connective tissue consisting of collagenous and elastic fibers, fibroblasts, sebaceous glands, blood vessels, smooth muscles, or inflammatory cells such as granulocytes, lymphocytes and macrophages), kidney or lung. There was, however, staining of some cells in the secretory segment of eccrine sweat glands from 2 patients, possibly corresponding to myoepithelial cells. Antigen expression was somewhat variable between cells from different melanomas as well as between individual cells from the same melanoma. The possible diagnostic value of this procedure for identification and classification of melanomas is discussed.

Adult↗
PubMed1982

Phenotypic and genotypic characteristics of a cell line from a squamous cell carcinoma of human skin.

A human cell line (SCL-1) from a poorly differentiating cutaneous squamous cell carcinoma (SCC) ws studied through 20 passages during 2 years. Cells maintained their original morphology with low degree of keratinization, as indicated by light and electron microscopy. The keratin peptide pattern resembled the type in SCC tumors, and the corresponding filaments were detected by immunofluorescence at all passage levels. Cells did not grow in soft agar but formed tumor-like nodules in an "organotypic" culture assay (on lifted collagen gels) and grew invasively after transplantation to immunosuppressed inbred C3H mice. After injection into BALB/c nu/nu mice, tumors of SCC morphology were formed. The hypodiploid tumor stem-line was maintained for about 10 passages, when a shift to hyperploidy started, as determined by chromosome and DNA flow microfluorometric analyses. Two stable marker chromosomes (in 100 and 70% of the metaphases, respectively), involving chromosomes 7 and 9, strongly indicated a monoclonal origin of this cell line.

Aged↗
PubMed1981

Correlation of prekaratin peptides and ultrastructure in epithelial cells of human skin tumors in vivo and in vitro.

Prekeratin was reduced in human skin malignancies comparing Bowen's carcinoma (BC), basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) with normal epidermis. This observation correlated with ultrastructural appearance and frequency of tonofilaments. Gel electrophoresis of tumor extracts revealed the decrease or loss of larger prekeratin peptides (65 to 68 K daltons) prominent in the epidermis. Biopsies, particularly from BC, resembled normal keratinocytes in culture with respect to their prekeratin patterns (48 to 61 K daltons). The pattern was most different, and prekeratin lowest, in SCC and derived cultures. In BCC-cultures, however, prekeratin (almost identical to keratinocytes) and filament formation significantly exceeded the respective tumor levels.

Bowen's Disease↗
PubMed1980

[Congenital paramedian lip fistulas].

Congenitale fistulae of the lower lip are mainly an aesthetic problem for the affected patients. Although the anomaly may be inherited as an isolated symptom for several generations, it is also indicative of a cleft palate or related syndromes. Since the possibility of additional severe malformations exists for the offspring genetic counseling of patients with fistulae of the lower lip should be considered.

Abnormalities, Multiple↗
PubMed1979

Pitted keratolysis (keratolysis plantare sulcatum). Ultrastructural study.

Biopsies from typical lesions of pitted keratolysis from five patients have been investigated by electron microscopy to provide information on colonization and morphology of the microorganisms involved in this disease. A part of the biopsies was inoculated in culture media, and Corynebacteria were selected for further examination. Electron microscopy revealed a great variability in the morphologic feature of bacteria concerning size, shape, capsule, cell wall, cross wall formation, plasma membrane, nucleoplasm, cytoplasmic organelles and constituents including mesosomes, ribosomes, volutin granules, and glycogen particles. The pleomorphism is thought to be due in part to the diversity of preparation techniques used in this study and in part to different growth conditions in vivo and in vitro. As a consequence the present findings are only partly comparable with previously published data on bacteria involved in skin diseases. Evidence is presented that bacteria inducing pitted keratolysis may be able to destroy keratin by means of hydrolytic enzymatic activity.

Biopsy↗