PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “MAMMARY NEOPLASMS, EXPERIMENTAL”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1982

Ultrasonic treatment of experimental animal tumours.

Studies on the effects of ultrasound on several solid tumours in experimental animals have indicated that tumour growth rates can be reduced. These data are generally consistent with a thermal mechanism of action. Application of combined ultrasound and X-irradiation have shown that with some experimental animal tumours the radiation dose required to locally control 50% of the tumours can be reduced by ultrasound. These results were also consistent with a thermal mechanism of action hypothesis. Fractionated X-irradiation was not enhanced as much as single dose. Pulsing the ultrasound with the same time-average intensity resulted in the same radiosensitivity enhancement. The combined effects of ultrasound and cancer chemotherapy drugs have been studied in mouse leukaemia. The treatment was applied in vitro with cells in suspension. Subsequent to treatment, the cells were inoculated into host mice and survival was monitored. Cytotoxic action of 5 of 10 drugs studied was enhanced by ultrasound. A thermal mechanism of action apparently was not involved. Cavitation in the suspension probably played a role in the cytotoxic enhancement. Experimental data are consistent with the concept that ultrasound causes rapidly reversible cell damage which, in the presence of cytotoxic drugs, is not so readily reversed and results in significant loss of lethal potential of the malignant cells to the host.

Animals↗
PubMed1980

Deficiency of nuclease activity in ribosomes of three tumor types.

Polysomes isolated from 3 types of neoplasms, mouse mammary adenocarcinoma designated DBAH, morris rat hepatoma 7777, and mouse chloroleukemia, do not undergo fast degradation upon incubation at 37 degrees C, unlike polysomes isolated from corresponding isogenic, normal tissues. Further,. 1M KCl extract of ribosomes from normal cells, in contrast to their neoplastic counterparts, stimulate degradation of poly(U). The nuclease activity in ribosomal preparations from neoplastic cells is not increased in the presence of p-chloromercuribenzoate, a blocking agent of RNAase inhibitor. This suggests that ribosomal preparations from tumor cells are free of nucleases rather than just being masked by an inhibitor. Ribosomes from neoplastic cells stimulate protein synthesis in vitro in the presence of endogenous or exogenous mRNA to a much higher degree than similar preparations from normal tissues. This event is in agreement with the deficiency of nuclease in polysomes from neoplastic cells.

Animals↗
PubMed1985

The involvement of a type-B retrovirus in the induction of thymic lymphomas.

A highly leukemogenic virus (DMBA-LV) (in vivo leukemogenic titer 1-5 X 10(6) IU/ml, and 35-40 days to thymic lymphoma detection) is produced by a chemical carcinogen-induced transplanted thymic lymphoma. The virus preparation is a mixture of a type-B retrovirus highly related to exogenous type-B retroviral isolates and a biologically defective type-C retrovirus. The DNA of DMBA-LV-induced-tumors contains new type-B proviruses but no additional type-C proviruses could be detected. The leukemogenicity of DMBA-LV was completely neutralized by a monoclonal antibody against MMTV envelope glycoprotein, but was not affected by a broadly reacting Friend MuLV anti-gp70 serum which effectively neutralizes type-C ecotropic, xenotropic, and recombinant retroviruses and which completely abolishes the leukemogenic activity of Moloney leukemia virus. Three type-B mammary tumor-inducing retroviral isolates, while containing type-C retroviral sequences, were not leukemogenic. A further characterization of the type-C retroviral sequences present in DMBA-LV indicated that sequences characteristic of endogenous, nonxenotropic proviruses are present. In addition, using a variety of type-C-specific retroviral DNA probes, no evidence was obtained for the presence of a type-B-C-recombinant genome in DMBA-LV. Leukemogenesis was absolutely dependent upon the presence of a functional type-B retroviral envelope gp 52 and DMBA-LV does not appear to contain a leukemogenic retroviral type-C genome.

Animals↗
PubMed1976

Leukemias and vaginal tumors induced in female Donryu rats by continuous administration of 1-butyl-3,3-dimethyl-1-nitrosourea in the drinking water.

Three groups of Donryu rats, each consisting of 36 females, were continuously given solutions of 1-butyl-3,3-dimethyl-1-nitrosourea as drinking water (400 ppm for group A, 200 ppm for group B 100 ppm for group C). Of the 100 rats that survived at least 122 experimental days, 64 developed leukemia and 38 had vaginal tumors. Leukemias were preponderant in animals of groups A and B; vaginal tumors appeared in group C.

Animals↗
PubMed1975

No evidence for particles encapsulating RNA-instructed DNA polymerase and high molecular weight virus-related RNA in herpesvirus induced tumours of non-human primates.

The simultaneous detection test gave no evidence for the presence of RNA tumour viruses in herpesvirus induced malignant lymphomas of non-human primates. The 12 tumours tested were obtained from three different monkey species inoculated with Herpesvirus saimiri or herpesvirus ateles. Particles encapsulating RNA-instructed DNA polymerase and high mol. wt. virus-related RNA were easily demonstrated in tumours of the mouse induced by type-C or type-B oncornaviruses and in human lymphoid cells infected with simian sarcoma virus type I which were examined in parallel. Attempts to demonstrate partial expression of an oncornavirus genome in the herpesvirus induced tumours and attempts to detect an interspecies antigen related to monkey oncornaviruses were negative and strengthened the observations made with the simultaneous detection test.

Animals↗