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Biomedical subjects

M Volm

Publications and source records attributed to M Volm.

At least 163 records · Page 9Linked to original sources
PubMed1980

Studies on the specificity of tissue supernatants on the proliferation of liver in baby-rats.

Supernatants (105,000 g) prepared from extracts of liver and kidney were injected at different concentrations into 10 day-old rats and the resulting effects on 3H-thymidine incorporation in liver, kidney and lung were measured over a period of 24 hours. Incorporation in all three organs is inhibited by supernatants from both liver and kidney, with maximal activity between 12 and 18 hours after injection. Fractions prepared from liver supernatant by ultrafiltration and alcohol precipitation also showed no specific effect on liver cells. In order to test whether the activity of any factors in the supernatants is cell-cycle dependent, organs of baby rats were synchronized by two different procedures: a) injection of a 3.5% casein solution, b) injection of hydroxyurea (2 x 10 mg/kg body weight with an internal of one hour). Inhibitory effects were only observed when the supernatants were injected during the G1-phase of the target cells. Supernatants prepared in a similar way from other organs such as spleen, lung or heart also inhibited thymidine incorporation in casein-stimulated liver from baby rats. All of our investigations have therefore failed to find any indication of tissue-specific activity in these extracts.

Animals↗
PubMed1980

Competing pathways in the formation of alkyl, alk-1-enyl and acyl moieties in the lipids of mammalian tissues.

The distribution of radioactivity from intravenously administered cis-9[1-14C]octadecenol into various tissues of the rat was studied as a function of time. The pattern of incorporation of radioactivity into alkyl, alk-1-enyl and acyl moieties of the lipids in heart, lungs, liver, intestine, kidney, brain and plasma revealed that oxidation of the long-chain alcohol and esterification of the resulting fatty acid to a wide variety of lipids are by far the most predominant reactions. Acylation of the long-chain alcohol is observed especially in liver, which appears to be the major site of biosynthesis of wax esters. Alkylation of the long-chain alcohol to alkoxylipids occurs in most tissues, most predominantly in the heart.

Acylation↗
PubMed1980

[Studies in vivo and in vitro on the influence of 5-fluorouracil and n'-(2'-furanidyl)-5-fluorouracil on the walker carcinosarcoma 256 in the rat (author's transl)].

We compare the effects of 5-fluorouracil and N'-(2'-furanidyl)-5-fluorouracil (Ftorafur) in vivo (tumor size) and in vitro ([6-3H]-deoxyuridine incorporation) on solid Walker carcinosarcoma of the rat. 5-Fluorouracil and Ftorafur have a dose-dependent effect on tumor size and on [6-3H]-deoxyuridine incorporation in vitro. The in vivo effects on tumor size are similar when the dose of Ftorafur calculated by its molecular weight is about 3 times higher than that of 5-fluorouracil. In vitro an about 650 times higher dose of Ftorafur is required to achieve a comparable reduction of [6-3H]-deoxyuridine incorporation in the tumor cells.

Animals↗
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

Kinetic complexity of nuclear poly(A)-containing RNA in normal and regenerating rat liver.

Poly(A)-containing RNA isolated from liver nuclei of untreated rats and 3 h or 12 h after partial hepatectomy or sham operation was hybridized to the complementary DNAs (cDNAs). In the homologous reactions two major components could be seen. When compared to normal liver, the complexity of the least abundant class was lower in nuclei from livers 3 h after partial hepatectomy and was higher in those isolated 12 h after operation. The heterologous reactions revealed an increase of some abundant poly(A)-containing sequences and a loss or dilution of rare sequences 3 h after operation. The latter effect was not specific to the regeneration process but occurred after laparotomy as well. 12 h after partial hepatectomy, however, about 10% new poly(A)-containing sequences were detected, corresponding to about 5000 molecules of 4500 nucleotides length, which are unique to regenerating nuclei.

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↗
PubMed1978

Detection of induced resistance in short-term-tests. Adriamycin-resistant sarcoma 180.

By treatment of the sarcoma 180 (ascites) with adriamycin over 30 passages in NMRI mice, an adriamycin-resistant tumor cell line was developed. The resistance could be detected both in animal experiments and in the short-term test. In spite of treatment of the sarcoma 180 with triaziquone over 50 passages, no resistance could be detected against triaziquone either in the in vitro test or in animal experiments. The necessary criterion for a pretherapeutic test of sensitivity or resistance--a good correlation between in vivo and in vitro results--was fulfilled in all experiments carried out.

Animals↗
PubMed1978

[Short-term incubation in vitro with precursors of nucleic acids on human primary tumors and metastases of carcinoma of the breast (author's transl)].

A technique of short-term tests in vitro by means of the incubation of tumor cell suspensions is utilized as a radioactive-biochemical method for pretherapeutic determination of the resistance in human cancers of the breast. Cell suspensions from primary tumors and metastases reveal individually different responses to cytostatics in vitro. It is possible, therewith, to differentiate two tumor collectives related to in vivo resistant or in vivo sensitive tumors. The responses of the primary lesion and the axillary lymphatic metastasis of the same carcinoma may in single cases also differ in vitro, according to clinical experience with the therapy of breast cancer. A distinct relation can be shown between the histological type of a carcinoma and its in vitro capacity of resistance.

Antineoplastic Agents↗