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Biomedical subjects

R Demuth

Publications and source records attributed to R Demuth.

4 recordsLinked to original sources
PubMed1999

Isoporphycene: The Fourth Constitutional Isomer of Porphyrin with an N(4) Core-Occurrence of E/Z Isomerism.

Liberation of the ligand from the nickel complex 1 obtained by template synthesis yielded isoporphycene (as the octaethyl derivative 2), the first constitutional isomer of porphyrin with an N(4) core for which E/Z isomerism is involved: Compound 2 is present as the E isomer, which is in rapid, presumably acid-catalyzed equilibrium with a small amount (2 %) of the Z isomer. The remaining unknown constitutional isomers of porphyrin are considerably higher in energy than the already rather labile isoporphycene, so that the latter should mark the border of existence for this type of structural variant of porphyrin.

Journal Article↗
PubMed1991

Bone marrow diagnosis in lymphoproliferative disorders: comparison of results obtained from conventional histomorphology and immunohistology.

In this study we have investigated 313 bone marrow biopsies from 280 patients with lymphoproliferative disorders. Trephines were sectioned transversely to obtain one cylinder for cryostat sectioning and immunostaining and a second for histomorphological evaluation using a plastic-embedding technique. The results obtained by histomorphological and immunohistological evaluation were compared for their contribution to staging and classification. Using both techniques, bone marrow involvement was seen in 3/43 (7.0%) biopsies from patients with Hodgkin's disease and in 193/270 (71.5%) cases with non-Hodgkin's lymphoma, including multiple myeloma and acute lymphocytic leukaemia. Immunohistology proved superior in detecting minimal mainly interstitial bone marrow infiltration in 15 leukaemia/lymphoma cases. Biopsies showing infiltration with both methods (n = 157) were re-examined for classification of lymphomatous infiltrates. Whereas immunohistology did not provide additional information in cases with Hodgkin's disease and myeloma, this method was crucial for establishing the definitive diagnosis in a number of cases with acute lymphocytic leukaemia and non-Hodgkin's lymphoma. In all of six leukaemia cases, in which no or inadequate material was available for immunophenotyping of cell suspensions, immunohistology clearly defined the subtype. In the 140 cases of non-Hodgkin's lymphoma the majority of cases (76.4%) were identically classified. In some cases, with important prognostic and therapeutic implications, immunohistology alone provided the definitive diagnosis: T-cell lymphoma (n = 2), hairy cell leukaemia (n = 2) and centrocytic non-Hodgkin's lymphoma (n = 3). Bone marrow immunohistology is, therefore, an important supplement for classical lymphoma/leukaemia diagnosis. The differences observed between histomorphology and immunohistology emphasize the importance of lymph node biopsy in lymphoma classification.

Biomarkers↗
PubMed1980

Using expanded polytetrafluoroethylene for bridging arterial microvascular defects: an experimental study with evaluation in the scanning electron microscopy.

In an experimental investigation the replacement of arterial microvessels with microporous expanded polytetrafluoroethylene was studied. The infrarenal segment of the rat aorta was used as the scientific model. The inside diameter of the micrograft was 1 mm. Using microvascular techniques a total of 18 prostheses were inserted. The animals were harvested at time intervals from 3 days up to 3 months. Patency was determined by angiography and at autopsy. The aorta implant junction, the characteristics of the neointima development and the differentiation of the interstitial cells were studied by scanning electron microscopy. Fourteen of the implanted micrografts remained patent at the time of sacrifice, yielding an early patency rate of 77,7%. As shown by scanning electron microscopy, the development of the neointima took place in 2 stages. The initial fibrin/platelet layer was reduced after one month and replaced by a definite neointima with mononuclear cells, connected with interstitial cells. Investigation of the aorta-implant junction showed the prosthesis functionally embedded in the structure of the aorta. Expanded polytetrafluoroethylene as a prosthetic material for microvascular prostheses was easy to handle and emerged compatible with other tissues. It can be used as a substitute for bridging arterial microvascular defects.

Animals↗