PubMed Health⌕ Search

Biomedical subjects

K Wayss

Publications and source records attributed to K Wayss.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Irradiation of solid Walker carcino-sarcomas after synchronisation with hydroxyurea (author's transl)].

Sprague-Dawley rats with solid Walker carcino-sarcomas were synchronized with hydroxyurea (HU; 6 x 50 mg and 1 x 300 mg HU/kg body weight) and then irradiated at different time points (60Co). The synchronized tumors showed a significant delay of growth when irradiation was applied in the late G1 phase, at the transition G1/S and in the early S phase. The remaining phases of the cell cycle, especially the S phase showed the same sensitivity as the non-synchronized controls. Improvement of therapy by irradiation after HU application was largely due to the synchronization of tumor cells. Only the increased therapeutic effect of irradiation shortly after application of HU can be explained also by combination of both HU and irradiation.

Animals↗
PubMed1979

Determination of trace elements in peripheral lymphocytes from tumor-bearing rats.

Neutron activation analysis of peripheral lymphocytes from healthy and Walker 256 carcinosarcoma-bearing rats resulted in the quantitative determination of Co, Cu, K, Mn, Rb, Se and Zn, and a qualitative determination of Au and Sb. From corresponding plasma samples, Co, Zn, Rb, Se and Cs were analyzed. Differences in trace element concentrations could only be detected in plasma of tumor-bearing animals which showed a decreased Zn and Co content of 50% and 30%, respectively, and a rise of Rb when compared to plasma of control animals.

Animals↗
PubMed1979

[Chemotherapy in solid transplantation tumors following synchronization (author's transl)].

In order to examine whether the effects due to cytostatics might be improved by synchronization, cytosin-arabinoside, hydroxyurea or Vincristin were administered to rats bearing solid transplantation tumors, at different intervals following synchronization. The three substances, interfering with the S-phase of the cells, show significantly improved therapeutic results with quickly proliferating Walker-carcinosarcoma after a synchronization by hydroxyurea. Cyclophosphamide on the other hand, being effective through several phases of the cell cycle, furnishes no evidence of any essential therapeutic result. Analogous therapeutic experimentation using slowly growing neurosarcomas yielded no better results after synchronization. The concept of synchronization treatment may be approved, therefore, with certain limitations: firstly, synchronization with hydroxyurea can be maintained for a short time only, and the cancerous cells pass throught the first phases of the cell cycle following synchronization for the most part together with normal cells; secondly, only tumors with an important growth fraction and only cytostatics that do not affect several phases of the cell cycle are appropriate for synchronization therapy.

Animals↗
PubMed1978

[Resistance testing and chemotherapy results of bronchial tumours (author's transl)].

In a pilot study of 40 patients with inoperable bronchiogenic carcinomas the results of clinical therapy were compared with those of in vitro tests by measuring the effects of cytostatic agents on the incorporation of precursors into DNA and RNA in tumour cells incubated in vitro for short periods. Tumour cells that showed little inhibition by the cytostatic agents in vitro (less than 30% inhibition at a concentration of 10(-2) mg/ml adriamycin) came from patients who responded poorly to cytostatic therapy. On the other hand, tumour cells that were strongly inhibited in vitro (greater than 30% inhibition) came from tumours which proved to be sensitive to the chemotherapy given to the patient. A strong correlation existed between the inhibition of uridine incorporation by the tumour cells in vitro by adriamycin and the responses of the tumour to clinical therapy even when combination-therapy was given without adriamycin. There was also a significant correlation between the inhibiting effect of adriamycin in vitro and the survival time of the tumour patients.

Bronchial Neoplasms↗
PubMed1977

Detection of induced tumour-resistance to cyclophosphamide by the in vitro short term test.

Treatment of the solid Walker carcinosarcoma of the rat for a period of one year with cyclophosphamide (40 mg/kg at each passage; tumours were transplanted weekly) resulted in the formation of a cyclophosphamide-resistant tumour cell line. Without further treatment, animals injected with non-treated or cyclophosphamide pre-treated cells survived for 10 days on an average. After therapy with cyclophosphamide (2 x 38 mg/kg), rats with non-treated tumour cells survived 22 days whereas those with pre-treated tumours survived only for 17 days. Tumour cells which were shown to be sensitive in vivo also exhibited a larger reduction in 3H-thymidine and 3H-uridine incorporation in the in vitro short term test after incubation with urine from cyclophosphamide-treated rats or with 4-hydroperoxy-cyclophosphamide. The resistance to cyclophosphamide which was detected in animal experiments with Walker carcinosarcoma can therefore also be observed using the in vitro short term test.

Animals↗
PubMed1977

Enhancement of incorporation of 131iododeoxyuridine into tumors after application of Clostridium oncolyticum s. butyricum (M 55). Animal experiments on positive scintigraphic localization of tumors.

The application of spores of the bacterium Clostridium oncolyticum s. butyricum (M 55) results in an increased incorporation of 131Iododeoxyuridine in tumors (amelanotic melanoma Fortner III of the golden hamster and Brown-Pearce carcinoma of the rabbit). This leads to an improved scintigraphic demonstration of the tumors.

Animals↗
PubMed1976

Clinical correlates of in vitro effect of adriamycin on advanced lung carcinoma.

The effect of 1.38 X 10(-5) M adriamycin on tritiated uridine incorporation was studied after 3 hours treatment of suspensions of 25 advanced human lung carcinomas in vitro. The results were correlated with the responses to clinical therapy. All tumours which showed an inhibition of uridine incorporation in vitro of more than 40% were also sensitive to clinical treatment with adriamycin.

Cells, Cultured↗
PubMed1975

[Failure to partial synchronization with hydroxyurea to improve results of chemotherapy of solid neurosarcoma in the rat (author's transl)].

Partial synchronization of the slow-growing cell of solid neurosarcoma in the rat can be achieved by blocking DNA synthesis with hydroxyurea. Possible augmentation after synchronization of the therapeutic effects achieved with various cytostatics was tested. The substances were administered to tumour-bearing rats at various times after synchronization (at the transition from G1 to S phase; at maximal DNA synthesis; at the transition from the S to the G2 phases; at mitosis) and therapeutic effects on tumour gs. Cyclophosphamide and adriamycin reduced tumour size, the effect being dose-dependent. No differences were noted between synchronized and non-synchronized cells. Hydroxyurea and vincristine had significantly less effect on the tumour cells, this minimal effect not being enhanced by synchronization. The reported results were obtained in tests on 360 rats and are statistically significant (double variance analysis).

Animals↗