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Biomedical subjects

P Gedigk

Publications and source records attributed to P Gedigk.

At least 19 recordsLinked to original sources
PubMed1984

Suppression and acceleration of DNA synthesis in megakaryocytes after partial hepatectomy.

3H-thymidine labelling indices of megakaryocytes were determined in the spleen and bone marrow of normal, sham-operated and partially hepatectomized rats. Compared with controls, the labelling indices were much lower in megakaryocytes but much higher in other cells such as erythroid cells or proliferating duodenal mucosal cells when measured in rats from 12 to 36 h after partial hepatectomy. From 48 to 72 h after hepatectomy the labelling indices of megakaryocytes became higher than control values. On the other hand the labelling indices of megakaryocytes from 12 to 36 h after sham operation were higher than controls. The accelerated DNA synthesis of megakaryocytes after sham operation was considered to reflect the additional DNA synthesis in this cell line which leads to an increase of the average ploidy level. The initial decrease in labelling indices of megakaryocytes after partial hepatectomy did not occur if serum from normal or thrombocytopenic rats was injected. These findings suggest that the liver may produce a humoral factor which influences the so-called endomitosis of megakaryocytes.

Animals↗
PubMed1984

Cell proliferation and growth of gastric carcinoma induced in inbred Wistar rats by N-methyl-N'-nitro-N-nitrosoguanidine.

Gastric carcinoma was induced in inbred Wistar rats by p.o. administration of N-methyl-N'-nitro-N-nitrosoguanidine for 25 weeks, and cell proliferation and growth of the gastric carcinoma in an incipient stage were studied. A microscopic cancer was found by 24 weeks, and macroscopic cancers were found after 27 weeks. All the cancers were a single lesion located at the midpoint of the lesser curvature of the stomach. Histologically, they were tubular adenocarcinomas. The mucosal changes predisposing to the development of carcinomas were focal erosions and dysplasias confined to the midpoint of the lesser curvature. The malignant transformation appeared to occur in the dysplastic cells of the eroded mucosa by 17 to 18 weeks after N-methyl-N'-nitro-N-nitrosoguanidine treatment. Following the malignant change, the labeling indices of the tissues with [3H]thymidine decreased, suggesting an elongation of cell cycle time. By repeated injections of [3H]thymidine, a time required for all the cancer cells to enter S phase (reflecting the maximum cell cycle time) was estimated to be about 3.5 days. This gave a theoretical doubling time for the gastric cancers. On the other hand, from the temporal observations of tumor volumes, it was shown that the gastric cancers in an incipient stage underwent exponential growth with a doubling time of 14 days. The difference between the theoretical and actual doubling time might reflect a cell loss rate in the cancer tissue.

Animals↗
PubMed1982

Regeneration of endocrine cells in the stomach.

A mucosal defect was produced by cryosurgery in the antral and the fundic wall of the rat stomach, and regeneration of gastric endocrine cells was studied 50, 100 and 200 days after operation. Fifty days after the operation, the mucosal defect was completely covered with regenerated epithelium. The regenerated mucosa both in the antral and in the fundic region consisted of mucinous glandular structures. The regenerated mucosa in the corpus remained pseudopyloric in type even 200 days after operation. Regardless of the time after operation, regeneration of endocrine cells was always observed. We could identify G cells and EC cells in the regenerated mucosa of the antrum, and EC cells, A cells and AL cells in the regenerated mucosa of the corpus, respectively. By electron microscopy, endocrine-exocrine cells were frequently encountered. These cells had two different types of intra-cytoplasmic granules; one was an endocrine-specific, small electron-dense granule, and the other a large, lucent mucin droplet-like granule. These findings indicate that the endocrine cells of the stomach are formed from endodermal precursor cells.

Animals↗
PubMed1981

Immunohistochemical localisation of alpha-fetoprotein (AFP) in germ cell tumours: evidence for AFP production by tissues different from endodermal sinus tumour.

20 germ cell tumours have been studied with respect to the presence of alpha-fetoprotein (AFP), using the peroxidase-antiperoxidase (PAP) technique. 6 out of 20 tumours contained elements of endodermal sinus tumour (EST) and were AFP positive. 16 tumours were diagnosed either as pure embryonal carcinomas (6) or as mixed germ cell tumours, containing elements of embryonal carcinoma (10). In 3 of these 16 tumours AFP was localised definitely in the embryonal carcinoma cells; in an additional 6, AFP was also detected but it could not be decided whether AFP was present in embryonal carcinoma cells or in EST cells during early differentiation. In 2 of 7 immature teratomas, AFP was shown to be present in cylindric epithelia. All seminomas (4) studied were AFP-negative. These results show that AFP, which occurs regularly in EST, may also be present in embryonal carcinomas as well as in immature teratomas. Thus, it seems that the immunohistochemical demonstration of AFP by the PAP technique is a suitable method of identifying late stages of embryonal carcinoma or early stages of endodermal sinus tumour during the process of differentiation.

Dysgerminoma↗
PubMed1979

Premalignant lesions of the stomach.

The histopathogenesis of the three major types of gastric carcinoma--intestinal, diffuse and indeterminate--is reviewed, considering normal and abnormal cell kinetics of the gastric mucosa. Intestinalization is a precursor of intestinal-type carcinoma and is related to environmental factors. Diffuse gastric carcinoma originates from dysplasia of the neck of the gland and is of nonenvironmental, probably genetic, origin.

Carcinoma↗
PubMed1977

[Ultrastructure of liver damage in chronic vinyl chloride intoxication (author's transl)].

Liver biopsies taken from 15 workers at a PVC-producing factory were examined by electron microscopy. The hepatocytes showed focal hydropic swelling, disseminated toxic steatosis, peculiar para-crystalline inclusions in enlarged mitochondria, focal cytoplasmic degradations, and occasional single cell necroses. These regressive changes were more prominent in cases with a shorter interval of non-exposure prior to the biopsy. Further, a focal compensatory hyperplasia of the smooth endoplasmatic reticulum was found. With increase of the non-exposure time interval, a regression of the degree of steatosis as well as an age-independent excessive lipofuscin deposition was seen in the hepatocytes. Apparently, these are sequelae of increased autophagia of lipids and increased lipid oxidation by the vinylchloride. In the sinusoids, activation, enlargement and proliferation of Kupffer cells was noted. The tendency of these cells to proliferate is apparently caused by the cancerogenic stimulation by vinylchloride. The prominent hyperplasia of lipocytes is probably connected with the deposition of collagen and the peculiar perisinusoidal fibrosis.

Chemical and Drug Induced Liver Injury↗
PubMed1977

[Particular aspects of testicular tumor in the elderly (author's transl)].

Malignant testicular tumors mainly occur in early adult life. 14 (7.8%) of our 180 patients with testicular tumors, treated from 1966 to 1976, were between 50 to 68 years of age. The pathological anatomical classification showed 9 germinal and 5 non-germinal tumors. To find out which tumor classification is the best for prognostic information and assessment of therapeutic consequences, we recommend setting up a central testicular tumor panel and register and refer to the multilateral study already initiated.

Aged↗
PubMed1977

Adenomatous changes and adenocarcinoma of glandular stomach in Wistar rats induced by N-methyl-N'-nitro-N-nitrosoguanidine. An electron microscopic and histochemical study.

Adenomatous changes, and early and invasive carcinomas of the glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine were studied. Almost all adenomatous changes and carcinomata were located near the midpoint of the lesser curvature. In electron microscopic and histochemical studies, both changes showed great cytological similarity. Electron microscopically, they were found to consist of predominantly undifferentiated cells with poorly developed cytoplasmic organelles, with some highly differentiated cells present. Histochemically, both showed strongly positive reactions for lysosomal enzymes. For tumor transplantation, five lesions were used and in all cases, the transplants were successful.

Adenocarcinoma↗
PubMed1977

[Central register and combined study of testicular tumors (author's transl)].

To successfully combat cancer, research needs to be based on prospective investigations and central collation of data. An initial report is presented concerning one such investigation that has been in progress since September, 1976: "central register and combined study of testicular tumors--Bonn." The aims are to collate epidemiologic data, achieve a standardization of the stages of the cycle of the seminiferous epithelium and of classification, on the model of the WHO, as well as to attain maximum efficiency of diagnosis and therapy. Fourteen participating clinics in the German Federal Republic, Austria, and Switzerland, and 70 submissions of data up to the 1st of March, 1977, amply justify the efforts so far expended and encourage us to solicit the cooperation of previous nonparticipants.

Adult↗
PubMed1976

Early changes of glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine (MNNG): with special reference to light microscopic, electron microscopic, and enzyme histochemical study of the regenerating epithelium induced by MNNG.

Early mucosal changes of the glandular stomach in Wistar rats ingesting N-methyl-N'-nitro-N-nitrosoguanidine were studied. Special attention was paid to clarifying the localization and chronological relationship between the expected regenerative changes and the succeeding carcinoma. For this purpose, drinking water of MNNG at a low concentration was given to the inbred Wistar rats which were sacrificed every second week during the first 35 weeks. In the 5th week, localized erosions appeared, which were constantly observed through about the 20th week. These changes were always located near the midpoint of the lesser curvature. Epithelial cells, which were found there, were studied with light and electron microscope, and with enzyme histochemistry. It has been observed that these cells corresponded with the so-called immature cells in the normal gastric epithelium and also with the regenerating epithelial cells, which were obtained from the vicinity of mechanically induced ulcer of the stomach. From about the 20th week 2 cases showing ectopic gland, 4 adenomatous changes, 2 early carcinomas, and 5 invasive carcinomas were found. All these lesions were located on the lesser curvature, near its midpoint, i.e. exactly the same area where regularly the erosions were observed.

Animals↗
PubMed1975

[Ultrastructure and morphogenesis of ceroid pigment. II. Late changes of lysosomes in Kupffer cells of rat liver after phagocytosis of unsaturated lipids (author's transl)].

Wistar rats were injected intravenously with cod liver oil emulsion. The lipid droplets ere phagocytized by Kupffer cells and stored in lysosomes. The transformation of these lipid-containing lysosomes into ceroid pigment granules was studied electron-microscopically and cytochemically for a period of 12 weeks after the injection. The lipid droplets enclosed in lysosomes show an increasing and continous condensation from the periphery towards the center due to oxidation and polymerization of unsaturated fatty acids. During the first week almost the total amount of the stored lipids is transformed into an amorphous, highly electron-dense material which disintegrates into cloddy and globular fragments during the following time. The fragments are embedded in a fine granular, slightly electron-dense matrix showing a marked activity of acid phosphatase. The lysosomal structures which contain remnants of condensed oxidized and polymerized lipids are the electron-microscopic equivalent of the granules as seen by light microscopy. These lipids, which have been changed in their molecular structure, cannot be hydrolized by lysosomal enzymes. They remain as an indigestible material, as a waste product in lysosomal residual bodies. Both lipofuscin and ceroid are lysosomal structures containing oxidized and polymerized lipids. The differences between these lipogenous pigments are due to their different formal and causal genesis. Lipofuscin develops in parenchymal and muscle cells by autophagocytosis and by subsequent oxidation and polymerization of segregated membrane lipids. Ceroid is formed in macrophages by heterophagocytosis of unsaturated lipid material which is also oxidized and polymerized.

Acid Phosphatase↗