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Biomedical subjects

T Hoffmann

Publications and source records attributed to T Hoffmann.

134 records · Page 8Linked to original sources
PubMedDate not supplied

Myeloid leukemia and myelodysplastic syndrome relapsing as granulocytic sarcoma (chloroma) after allogeneic bone marrow transplantation.

Of 229 consecutive patients receiving allogeneic blood or bone marrow stem cell transplants for acute myeloid leukemia, chronic myeloid leukemia, or myelodysplastic syndrome between 1974 and 1996, 52 patients relapsed. The original tumor recurred as granulocytic sarcoma (chloroma) in three patients (1.3%). Chloroma was found in the ovary in two patients and in the central nervous system in one patient. None of these three patients had experienced > or = grade II acute or more than limited chronic graft-versus-host disease. The intervals between transplantation and recurrence with chloroma were 2, 6, and 13 years. Two patients received a second transplant, and all three died of treatment sequelae.

Adult↗
PubMedDate not supplied

Receptors and signalling components of plant hormones.

Recent advances in understanding plant hormonal signalling has resulted in the identification of a variety of signalling components including receptor kinases with homology to the bacterial two component system as well as serine/threonine kinases and protein phosphatases. In addition, the existence of MAP kinase pathways in plants indicates a similar role of these signalling cascades in the relay of exogenous signals into the nucleus as has been disclosed in animal cells. The emerging signalling pathways of the plant hormone abscisic acid and ethylene are presented.

Abscisic Acid↗
PubMedDate not supplied

Establishment and characterization of four cell lines derived from human head and neck squamous cell carcinomas for an autologous tumor-fibroblast in vitro model.

To study interactions between tumor cells and stromal elements, we established carcinoma cell lines as well as tumor-derived and skin fibroblast cultures from four patients with squamous cell carcinoma of the head and neck. For the characterization of the tumor cell lines we a) determined population doubling times, b) assessed morphological features by light and electron microscopy, c) investigated the expression of typical markers by immunohistochemistry, including various intermediate filaments and surface antigens, d) compared these findings with expression patterns in the respective original tumor specimens, e) evaluated p53 mutations in tumor specimens and cell lines, f) performed chromosome analysis, g) investigated the tumorigenicity in athymic mice, and h) tested the formation of both tumor and mixed tumor-fibroblast multicellular spheroids. Tumor cell cultures were considered established cell lines when maintained and passaged over a period of two years after primary explantation. The in vitro morphology of the cell lines showed well preserved characteristics of squamous cell carcinoma, and electron microscopy as well as immunohistochemistry revealed their squamous type of differentiation. All cell lines presented the same p53 genotype as the respective original tumors. Furthermore, they were successfully xenotransplanted into nude mice and formed both pure and mixed three dimensional spheroids. This experimental model allows the in vitro and in vivo investigation of various tumor-fibroblast interactions.

Adult↗
PubMedDate not supplied

[An assessment of the variations in periodontal pathology in adolescents].

Forty-seven adolescents with periodontal abnormalities were examined using clinical, immunologic, and functional tests (altogether 12 signs). Factor analysis helped cut down the number of signs just to 4 major factors. Interpretation of these factors and consideration of the individuals in factor space permitted singling out at least 2 types of periodontitis course, requiring, possibly, different approaches to therapy.

Adolescent↗
PubMedDate not supplied

Antitumor activity of anti-epidermal growth factor receptor monoclonal antibodies and cisplatin in ten human head and neck squamous cell carcinoma lines.

Head and neck squamous cell carcinomas (HNSCC) frequently display increased levels of epidermal growth factor receptor (EGFR) and since the receptor is located on the cell surface, anti-EGFR antibodies appear to be suitable agents for antitumor therapy. We investigated the effect of murine EMD 55900 and rat ICR 62 monoclonal antibodies (MAb) directed against EGFR both as single agents and in combination with cisplatin. ELISA detection showed the amount of EGFR protein in HNSCC lines UM-SCC-10A, -10B, -11B, -14A, -14B, 14C, -22B and HLac 79, 8029NA, 8029DDP to range between 20 and 8100 fmol/mg protein. Compared to A431 cells, seven HNSCC lines were high and three low receptor expressors. Only low levels of TGF alpha were found in the supernatants of some untreated HNSCC lines, probably due to the consumption of TGF alpha by EGFR. Consequently, occupation of EGFR by MAb led to marked accumulation of TGF alpha in cell supernatants. Colorimetric MTT assay showed both MAbs (0.3-30nM) to have comparable dose-dependent growth inhibition which correlated with the EGFR content of the respective cell lines (p < 0.05). Using 30nM MAb, seven high receptor expressing HNSCC lines were growth inhibited by at least 20% to a maximum of 61% (mean = 38%). Combined treatment with MAb and cisplatin led to a significant decrease in cisplatin IC50 values in 5 cell lines expressing more than 1200 fmol EGFR/mg (dose modification by factor 2.1-4.1). In conclusion, anti-EGFR MAb exert direct antiproliferative activity in HNSCC lines and show additive effects in combination with cisplatin.

Animals↗