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Biomedical subjects

D Gericke

Publications and source records attributed to D Gericke.

At least 37 records · Page 2Linked to original sources
PubMed1983

[Microbiological short-time tests for the evaluation of mutagenic potential of chemical substances].

During the last 20 years it became much more interesting to test new chemicals as fast as possible for their carcinogenic potency. Therefore new test models were developed. Mutagenicity seems to be one sign for carcinogenicity. Therefore test systems using microorganisms were studied which are influenced by mutagenic substances. These systems are described, first of all the Ames-Test, using revertants of Salmonella typhimurium, secondly the Escherichia coli system deficient of DNA-polymerase A (DNA-Pol A-). The yeast Saccharomyces cerevisiae was introduced some years ago and finally the Neurospora crassa system serves as an additional test to define exactly the localisation of mutations. The tests and their problems are discussed.

DNA Polymerase II↗
PubMed1983

[Possibilities of immunologic management of Brown-Pearce carcinoma in rabbits].

The efficacy of the active specific immunotherapy and immune prophylaxis against the Brown Pearce carcinoma in rabbits was tested. The tumor cells taken as antigens were either untreated or treated with Mitomycin C combined or not with vibrio-cholerae-neuraminidase. The immune prophylaxis using tumor cells prepared this way proved to be very effective. In contrast, immunotherapy of rabbits with tumors was not effective, even when immunization was started directly after transplantation. Possible mechanisms were analyzed in-vitro and in-vivo assays. The cellular reactivity of sensitized spleen cells was positive, the humoral reaction was weaker. This kind of reaction could only be demonstrated with tumor cells pretreated with vibrio-cholerae-neuraminidase. The findings shall only be discussed with respect to the possible causes of ineffective immunotherapy.

Animals↗
PubMed1983

Morphology of the urinary bladder following long-term experimental irritation of the urothelium.

10 female beagle whelps received an artificial urinary calculus (1.5 ml of a rapidly polymerizing methyl-methacrylate) by means of a transurethral procedure. The X-ray, cytological, endoscopic and bioptic findings were followed in a long-term experiment. After a period of 61 months, precancerous urothelial changes (n = 1) and invasive urothelial microcarcinomas were found (n = 2). Typical changes from earlier controls were pseudopapillary follicular cystites. Chronic irritation of the urothelium is shown to be an important factor in the pathogenesis of urinary bladder carcinoma. Decisive is the length of the period of irritation rather than the actual material used in making the pellet.

Animals↗
PubMed1982

[Problems concerned with microbial mutagenicity tests].

Mutagenicity tests using microorganisms are the Salmonella-typhimurium test (Ames), the test with a polymerase A deficient Escherichia coli, the Saccharomyces cerevisiae D3 system and the Neurospora crassa test. Differences in results of Ames-test may be due to differences preserving the tester strains, the choice of solvent and the dosage of the test compounds, last not least is the production of S-9. The polymerase A deficient Escherichia coli system seems easier to handle than the Saccharomyces cerevisiae- or Neurospora crassa-test. The metabolic activation with different forms of S-9 is needed in the Salmonella- and the Escherichia coli-system. Nevertheless it is not possible to decide if a substance is carcinogenic for human beings or animals with microbial mutagenicity tests only.

Carcinogens↗
PubMed1982

[Results of local transurethral high frequency hyperthermia in bladder carcinoma (author's transl)].

On the basis of controversial results from clinical use of hyperthermal irrigation of the bladder lumen published by various authors a procedure was developed for transurethral local high frequency hyperthermia using phantom experiments and experimental bladder tumors. Encouraging results from experiments on animals led to clinical use of this technique with pretreated recurring bladder tumors (n = 64) at various stages. Poorly differentiated tumors at higher stages responded especially well. Typical pathohistological findings induced by hyperthermia were in these cases extensive tumor-necroses, and as late finding stromahyalinoses. Permanent changes of tumorfree urothelium have not been observed. During the observation period up to the present (maximum 48 month) the 3-year-survival rate has been 92.5% (T1G2-3), 59.4% (T2G3) and 22.0% (T3G3).

Adult↗
PubMed1980

[Chemically induced transplantable carcinomas of the urinary bladder in dogs (author's transl)].

It takes 24 months to induce preinvasive carcinomas in the urinary bladder of dogs as reported in the literature. The transplantation of chemically induced carcinomas has never been successful. Therefore, it was looked for methods which enable a shortening of the latency period and to transplant such tumors. 12 of 22 female beagle whelps were injected transurethrally with fast polymerizing plastics and then they have been treated subcutaneously with ortho-aminodiphenyl, formylaminonitrofurylthiazole or with the two carcinogens together. The dogs have been controlled by endoscopy, cytology and histology every 4 weeks. The first invasive urothelial carcinomas were observed 13 months after starting the treatment. Totally 7 carcinomas of the bladder and 3 in the pelvis of the kidney were found. It was possible to cultivate tumor material in tissue culture, gained by biopsy transurethrally. The transplantation of tissue culture material into nude mice was successful in 19 of 23 animals. In 2 of 10 beagles tumors started to grow transiently after transplantation of tissue culture cells. In the bacterial mutagenicity test (Ames) and in animals ortho-aminodiphenyl was neither mutagenic nor carcinogenic. However, it was cocarcinogenic if used together with formylaminonitrofurylthiazole.

Aminobiphenyl Compounds↗
PubMed1980

Induction of a transplantable urinary bladder carcinoma in dogs.

We attempted to reduce the carcinoma induction latency period and to produce a transplantable urinary bladder cancer in dogs. After transurethral pellet application, 12 of 22 female beagles were given subcutaneous injections of orthoaminodiphenyl, FANFT, or both. Monthly cytologic and histologic checks yielded the earliest evidence yet obtained for invasive urothelial urinary bladder carcinoma (15 months); seven urothelial carcinomas of the urinary bladder and three of the renal pelvis were established. Tissue cultures of the urothelial carcinomas in vitro were successful. Transplantation of tumor cells to 23 nude mice resulted in tumor growth in 19. Transplantation to 10 beagles yielded 2 tumors very quickly, but the tumors were rejected within 4 weeks.

Animals↗
PubMed1979

Mutagenic activity of cytostatic methyl hydrazones with different strains of Salmonella typhimurium.

Experiments are performed to ascertain the mutagenic properties of four new cytostatic methyl-hydrazones in the Ames test using different strains of Salmonella typhimurium. As could be demonstrated all four hydrazones are mutagenic per se without a metabolic activation through rat liver microsomes (S-9 fraction). Whereas the beta-chloroethyl hydrazones B1 and B2 cause a base-pair substitution with the strains TA100 and TA1535 the methyl-hydrazones EB4 and CyB4 both cause base-pair substitution with TA100 and frameshift mutation with TA98. At both strains the mutagenic activity of Cy84 ist powerful. Furthermore, no relation could be detected between the mutagenic properties of the methyl-hydrazones and their alkylating behaviour on 4-(4-nitrobenzyl)-pyridine.

Methylhydrazines↗