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Biomedical subjects

P Meister

Publications and source records attributed to P Meister.

At least 55 records · Page 3Linked to original sources
PubMed1988

[Soft tissue sarcomas. Classifying and/or grading?].

Grading of soft tissue sarcomas cannot substitute for their accurate classification. The latter, according to the historical typing of soft tissue tumors, as proposed by WHO (1969), has to be considered as presumptive for morphological grading. The parameters given for grading are subject to individual bias and artefacts. They are also influenced by the "histogenetic types" of tumors. To achieve some correlations between morphological grading and prognosis, grading parameters (atypia and mitotic activity) have to be weighted differently, according to tumor type. Immunohistochemical methods are helpful in accurate typing of tumors where classification is difficult. The future search will be concerned with more objective methods for grading, including immunohistochemical determination of proliferative markers (similar to Ki67) or flow-through cytophotometry. All efforts are oriented to achieving an optimal correlation between grading parameters on the one hand, and prognostic predictions on the other.

Fibrosarcoma↗
PubMed1986

[Immunohistochemical methods in the diagnosis and differential diagnosis of mesenchymal skin tumors].

TNM classification, including staging and grading, cannot replace histogenetic classification of mesenchymal skin tumors; moreover, histogenetic classification is the basis for correct interpretation of the morphological criteria of malignancy. Histogenetic tumor classification can be improved by special methods, such as immunohistochemical studies of routinely formalin-fixed, paraffin-embedded material; such studies are especially advantageous in tumor diagnosis. Immunohistochemical methods are also useful in classifying less well differentiated mesenchymal tumors, which otherwise would be descriptively designated as round-celled, spindle-celled, pleomorphic, myxoid, epitheloid or pericytomalike sarcomas. Moreover, further knowledge can also be acquired about tumors with characteristic structure, but uncertain histogenesis. A prerequisite for optimal results is careful comparison of the morphological findings with routine (H&E) strains and immunohistochemical reactions. Thus, overinterpretation and misinterpretation can also be avoided in artefacts which, if misinterpreted, could have grave consequences.

Diagnosis, Differential↗
PubMed1985

Epitheloid hemangioendothelioma of the scalp. A case report with immunohistochemical and ultrastructural study.

A case of an epitheloid hemangioendothelioma of the skin and subcutaneous tissue of the scalp is described. Clinically and histologically a (metastatic) carcinoma had been considered in differential diagnosis. Of great help in recognition of the endothelial nature of this tumor was the immunohistochemical reaction with Factor-VIII associated antigen and Ulex europaeus antigen. Not only tumor cells in solid areas, but also intracytoplasmic vacuoles revealed positive staining. Thereby it could be shown, that this paranuclear vacuoles are actually compatible with developing capillary lumina. Only few tumor cells showed positive reaction with alpha-1-antichymotrypsin, pointing to a possible small histiocytic component of this tumor. Endothelial features of tumor cells and developing capillary lumina also could be demonstrated by electronmicroscopy.

Aged↗
PubMed1984

N-Hydroxy-N-arylacetamides. I. Toxicity of certain polycyclic and monocyclic N-hydroxy-N-arylacetamides in rats.

Of the two carcinogenic N-hydroxy-N-arylacetamides tested, N-hydroxy-4-acetylaminobiphenyl was as active as the monocyclic analogs in the oxidation of hemoglobin, whereas N-hydroxy-2-acetylaminofluorene produced less ferrihemoglobin after IP injection into female and male rats. Monocyclic N-hydroxy-N-arylacetamides, such as N-hydroxy-4-chloroacetanilide or N-hydroxyphenacetin, were more toxic than the parent N-arylacetamides, LD50 in mice being 190 mg/kg for N-hydroxy-4-chloroacetanilide vs 755 mg/kg for 4-chloroacetanilide, and 702 mg/kg for N-hydroxyphenacetin versus 1,220 mg/kg for phenacetin. The higher acute toxicities are probably due, at least in part, to the production of more ferrihemoglobin by the N-hydroxy-N-arylacetamides. Chronic toxicity of N-hydroxy-4-chloroacetanilide was tested on 10 male and 10 female Sprague Dawley rats after IP or SC injection of 20 mg (0.11 mmol)/kg twice weekly for 16 weeks into two groups of 10 animals each (five males, five females, total dose: 3.5 mmol/kg). The experiment, which was terminated after 2 years, did not yield any hint that N-hydroxy-4-chloroacetanilide was carcinogenic in the rat. Subchronic toxicity of N-hydroxyphenacetin was tested in two experiments on male and female Sprague Dawley rats after IP or SC injection of 50 or 100 mg (0.26 or 0.51 mmol)/kg. In the first experiment, two groups of 15 rats each (seven males, eight females) were injected either IP or SC with 50 and 100 mg/kg twice weekly for 29 weeks, and in the second experiment groups of 10 males and 10 females were injected SC with 100 mg/kg twice daily on 5 days a week for 12 weeks. The experiments, which were terminated after 29 weeks and 12 weeks treatment, respectively, did not provide evidence for chronic interstitial nephritis or tumor growth in the kidney. N-Hydroxy-N-arylacetamides were found to be inferior to the corresponding arylhydroxylamines in their ferrihemoglobin-forming capabilities in female rats. Large differences in activity of the arylhydroxylamines and no close relation to the number of rings was observed, N-hydroxy-2-acetylaminofluorene being the least active and N-hydroxy-4-acetylaminobiphenyl being as active as the monocyclic compounds, and exceeding all in the duration of its activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetamides↗
PubMed1984

Distribution of lysozyme (muramidase) and alpha 1-antichymotrypsin in normal and neoplastic epithelial tissues: a survey.

Lysozyme and alpha 1-antichymotrypsin are useful in differentiation of histiocytic tumours. Both enzymes, however, also can be expressed in epithelial tissues. In contrast to lysozyme, alpha 1-antichymotrypsin is more often found to be positive in non-histiocytic neoplasias. In general, the activity of parent tissue is retained in tumour cells. In malignant melanoma and in single cases of other epithelial tumours an activity of alpha 1-antichymotrypsin was found which could not be demonstrated in normal parent tissue and which may find its explanation in a dedifferentiation of tumour cells.

Chymotrypsin↗
PubMed1984

[Cutaneous leiomyosarcoma].

Primary cutaneous leiomyosarcomas are rare mesenchymal skin tumors with relatively good prognosis and low risk of metastasis if there is no subcutaneous involvement. A 48-year-old patient with a primary cutaneous leiomyosarcoma of ten years duration is described. Therapy and differential diagnosis are discussed.

Breast Neoplasms↗
PubMed1982

Extracardiac rhabdomyoma: report of different types with light microscopic and ultrastructural studies.

Five extracardiac rhabdomyomas were studied by light and electron microscopy: two of the adult type, two of the fetal type, and one of the female genital tract type. The three types can be distinguished histologically and ultrastructurally. Adult type rhabdomyomas are encapsulated and reveal histologically closely packed, large tumor cells with granular or vacuolated cytoplasm and only scant stroma. Electron microscopically, myofibrils are haphazardly arranged with rodlike Z-band material. Sometimes a sarcomeric arrangement of myofibrils is seen. The tumor cells are packed with mitochondria bearing lamellar inclusions. Fetal type rhabdomyomas contain a mixture of muscle cells in different stages of differentiations; the amount of stroma is increased. The myofilaments are usually disorganized and in only a few cells is rodlike Z-band material found. The cytoplasm reveals few mitochondria. In the rhabdomyoma of the female genital tract, the tumor cells are large and resemble more mature muscle fibers; the stroma is abundant and the myofilaments are usually arranged in an orderly fashion. Generally, the prognosis for rhabdomyomas is good. Metastases are not known. Two of the five rhabdomyomas studied recurred. One rhabdomyoma was found at autopsy. Embryonal rhabdomyosarcoma must be considered in differential diagnosis particularly for fetal type rhabdomyoma.

Abdominal Neoplasms↗