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Biomedical subjects

U Mohr

Publications and source records attributed to U Mohr.

At least 19 recordsLinked to original sources
PubMed1992

Atypical malignant mesotheliomas with osseous and cartilaginous differentiation after intraperitoneal injection of various types of mineral fibres in rats.

The histopathological appearance of malignant mesotheliomas with osseous and cartilaginous differentiation is described in detail. Bone and cartilage occurred in mixed and sarcomatoid mesotheliomas which were induced by intraperitoneal injection of various types of asbestos fibres (asbestos cement, crocidolite, UICC-amosite, UICC-chrysotile B, Calidria-chrysotile). Bone or cartilage were found in 32.7% of mixed mesothelioma and in 12.8% of sarcomatoid mesotheliomas.

Abdominal Neoplasms↗
PubMed1992

Cardiac metastases of induced lung carcinomas in rats.

A detailed study was made of seven cardiac metastases resulting from induced lung carcinomas. Fifty-six metastasizing lung carcinomas were found in Hann: Wistar rats as a result of subcutaneous injection of DPNA (dipentylnitrosamine). Of these 56, seven (12.5%) metastasized to the heart (three adenocarcinomas and four adenosquamous carcinomas). The metastatic tumors were located in the epicardium, myocardium, or endocardium, and their histologic appearance conformed to that of the primary lung carcinomas. The frequency of the cardiac metastasis and the preference of location within the heart were comparable with human cases.

Adenocarcinoma↗
PubMed1992

Cytokeratin filaments of the liver of BALB/c mice as a sensitive marker of liver damage. Computer-aided characterization with the image analysing system "IBAS".

The cytoskeleton forms a complex structural network which is of major importance for both structural integrity and physiologic functions of the cell. The aim of the present investigation was to investigate whether hepatotoxic effects of nitrosamine and colchicine can be detected through changes in the cytokeratin filament system which is an important component of the cytoskeleton. Groups of 10 male and 10 female newborn BALB/c mice were treated with either 25 micrograms dimethylnitrosamine (DMN) injected intraperitoneally on the day of birth; or with a daily subcutaneous injection of 0.12 micrograms/kg b.w. colchicine starting at ten weeks of age. A third group of mice served as untreated controls. All animals were held under standard laboratory conditions until necropsy at 16 weeks of age. The group injected with DMN received 0.05% phenobarbital with their drinking water after weaning. The histologic changes in the liver tissue were characterized by light microscopy. Changes of the cytokeratin filaments were visualized by the indirect immunofluorescent technique and quantified by using the image analysing system "IBAS". The cytokeratin filaments in the DMN group were markedly increased in amount and had a variety of morphological alterations. These effects could be measured quantitatively and did not indicate any sex-dependent behavior. The colchicine group did not display any structural changes in the cytokeratin filaments but sex-dependent changes in the amount of keratin material was revealed by image analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗
PubMed1992

RITA--Registry of Industrial Toxicology Animal-data--progress of the working group.

A data base for the collection of histopathological diagnoses of neoplastic and pre-neoplastic lesions and related data from control animals involved in long-term carcinogenicity or toxicity studies has been operated since 1988. Factors which may have an influence on the spontaneous tumor rate are integrated in the data base. Systematized nomenclature and standardized diagnostic criteria have been established as well as the applied data acquisition and data validation procedure.

Animals↗
PubMed1992

Effects of dipentylnitrosamine (DPNA) on the respiratory tract of rats.

Wistar rats (40 males and 40 females), treated over a period of 25 weeks with subcutaneous injections of dipentylnitrosamine (DPNA) at doses of 0, 62.5, 125 and 250 mg/kg body weight showed dose-dependent, sex-related, proliferative and metaplastic alterations in the upper and lower respiratory tract within one year. The biologic behavior of the induced lung tumors is very similar to that of human lung adenocarcinomas.

Adenocarcinoma↗
PubMed1992

Osteochondroma in laboratory rats: a report of 3 cases in a Fischer-344, a Sprague-Dawley, and a Wistar rat.

Three cases of osteochondroma in a male Sprague-Dawley (SD) rat, a female Fischer (F344) rat, and a male Wistar rat are described. The rats were aged between 26 and 30 months. All osteochondromas were considered to be of spontaneous origin. The Wistar rat had multiple osteochondromas on both hind legs, the skull base, and a lumbar vertebra, whereas each of the F344 and SD rats was affected by a solitary osteochondroma, also on a lumbar vertebra. The lumbar osteochondromas were similar in appearance in all rats and consisted of a central core of trabecular bone, interspersed with fatty marrow and covered by a cap of hyaline cartilage. The additional tumors in the Wistar rat represented different developmental stages of osteochondroma with or without endochondral activity. The osteochondromas in the rats were morphologically similar to those described in humans and some domestic animal species.

Animals↗
PubMed1992

Visual documentation of neoplasms as part of the REGISTRY Nomenclature Information System.

The REGISTRY Nomenclature Information system (RENI) is a program which runs on IBM-compatible personal computers. It includes internationally accepted diagnostic criteria for tumors and pre-neoplastic lesions in the rat to be used in toxicologic pathology. A video disk system, connected to the computer, provides colored pictures of histopathological reference slides, which are used for a visual documentation of the written criteria.

Animals↗
PubMed1979

Spontaneous endocrine tumors in Sprague-Dawley rats.

Spontaneous endocrine tumors were found in 81 of 100 Sprague-Dawley rats (42 males and 39 females) which survived for more than 2 years. Most of these tumors were medullary carcinomas of the thyroid, followed by tumors of the anterior pituitary gland, pheochromocytomas and cortical adenomas of the adrenal gland, and islet cell tumors of the pancreas. Multiple occurrence of these tumors was frequently observed. This study describes the morphology of these spontaneous endocrine tumors.

Adrenal Gland Neoplasms↗
PubMed1979

Tubular explant culture of fetal Syrian golden hamster tracheae.

Two types of organ culture technique (stationary and rocking) were compared for their ability to maintain the epithelial structures in the tubular explants of fetal Syrian golden hamster tracheae. A simple new technique has been devised for the organ culture of small tubular explants of fetal tracheae. A large pore-sized membrane filter is introduced into the rocking culture, which improves unfavourable in vitro effects of the stationary technique.

Animals↗
PubMed1979

Effects of serum concentrations on the clonal growth of Syrian golden hamster fetal lung cells.

In order to gain an insight into the mechanisms of clonal growth of early-passage Syrian golden hamster fetal lung (SGHFL) cells, a study was undertaken, in which the effects of various serum concentrations on the cloning efficiency and on the colony size of these cells were examined. The results suggest that both cloning efficiency and colony size are influenced by at least two factors present in the serum.

Animals↗
PubMed1979

Investigations on the carcinogenic burden by air pollution in man. Intratracheal instillation studies with benzo[a]pyrene in a mixture of Tris buffer and saline in Syrian golden hamsters.

Syrian golden hamster received intratracheal instillations of 0.125, 0.25, 0.50 or 1.0 mg benzo[a]pyrene (B[A]P) in a mixture of Tris buffer and physiological saline once weekly for life. Papillary polyps, squamous cell papillomas and carcinomas developed in both the larynx and trachea. In addition, bronchiogenic adenomas, adenocarcinomas and squamous cell carcinomas were induced in the lung. The highest incidence of respiratory tract tumours (83%) was seen in hamsters receiving 0.25 mg B[a]P. The results of these investigations are statistically evaluated and discussed.

Air Pollutants↗
PubMed1979

Tissue differentiation as a prerequisite for transplacental carcinogenesis in the hamster respiratory system, with specific respect to the trachea.

The significance of tissue differentiation for the transplacental carcinogenicity of DEN was examined. In one experiment, pregnant Syrian golden hamsters received a single sc injection of DEN on one of the different days of pregnancy. Approximately 95% of the offspring of those mothers treated on one of the last 4 days (days 12--15) of gestation developed respiratory tract tumors. Transplacental DEN treatment before the 12th prenatal day failed to induce any neoplastic response in the young. In the second experiment, the differentiation of the prenatal Syrian golden hamster tracheal epithelium was examined histologically and by electron microscopy. We found that on the 12th prenatal day the ER occurred for the first time in its functionally competent form. On earlier prenatal days, the epithelial cells lacked this organelle. We conclude that this development of ER is a prerequisite for transplacental DEN carcinogenesis, since this organelle contains the nonspecific enzyme systems necessary for the transformation of DEN to its ultimate carcinogen.

Animals↗
PubMed1978

Epithelial alterations in fetal tracheal explants of Syrian golden hamsters exposed to diethylnitrosamine in utero.

The fetal tracheae (13th--15th day of gestation) of Syrian golden hamsters exposed in utero to diethylnitrosamine (DEN: 200--400mg/kg body wt.) were divided into cranial and caudal halves. Both sections were then organ-cultured for 4--6 weeks. The cranial explants developed 1.5 times as many epithelial tracheal lining alterations as the caudal explants. These changes were found 25--42 days after the beginning of explant culture and histologically demonstrated hyperplasia, metaplasia and dysplasia. No alterations occurred in the control explants.

Animals↗
PubMed1978

The carcinogenic effect of dimethylnitrosamine in laboratory bred European hamsters (Cricetus cricetus).

The carcinogenic effect of dimethylnitrosamine (DMN) s.c. injected at two different dose levels was studied in laboratory bred European hamsters (EH) and data compared to findings for captured EH. Malignant haemangioendotheliomas of the liver and kidney, hepatocellular carcinomas and cholangiocarcinomas were induced. In contrast to the results obtained with wild EH, a large number of the laboratory bred females additionally developed ovarian granulosa cell tumors.

Animals↗