SEARCH · PubMed Health
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.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Logarithmically growing Yoshida sarcoma cells were treated for 1 h with low (2 decades cell kill) or high (more than 6 decades cell kill) doses of alkylating agents. Pulse and chase labelled DNA from treated cells were studied by alkaline sucrose gradient centrifugation. Nitrogen mustard (HN-2), 4-hydroperoxycyclophosphamide (CY-OOH), melphalan (L-PAM) and chlorambucil (CA) had no effect on the elongation rate of newly replicated DNA, both at low and high doses, although per cell the rate of DNA synthesis declined as inferred from the rates of [3H]thymidine incorporation compared to the increase in numbers of S phase cells in the treated populations. It is concluded that these drugs act specifically on the initiation step of the DNA replication, leaving chain elongation undisturbed. At low doses the chemically related sulphur mustard (SM) had also no effect on the maturation of new DNA but at high doses a decreased elongation rate was observed. A transient inhibition of chain growth was observed following treatment with a low dose of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). In contrast, the intercalating agent adriamycin showed a severe but delayed effect resulting in an almost complete block of the maturation.
The Yoshida sarcoma, a malignant rat tumor, has been reported by Machinami ( Machinami , R. (1972) Acta Pathol. JPN 22, 19-39) to destroy cartilage matrix in vivo. We have characterized an enzyme secreted by Yoshida sarcoma cells in culture which degrades cartilage proteoglycan in solution and also in situ in organ culture ( Mikuni - Takagaki , Y., and Gross, J. (1981) in Proceedings of the 6th International Symposium on Glycoconjugates ( Yamakawa , T., Osawa , T., Handa , S., eds) pp. 491-492, Japan Scientific Societies Press, Tokyo) ( Mikuni - Takagaki , Y., and Gross, J. (1982) in The Extracellular Matrix ( Hawkes , S., and Wang, J.L., eds) pp. 379-385, Academic Press, New York). In this report we characterized the isolated enzyme with the help of a new assay system for measurement of proteoglycan core protein degradation, which utilizes aminopropyl glass beads derivatized with hyaluronic acid. This enzyme, with a neutral pH optimum and apparent molecular weight of about 30,000, is secreted into culture medium in an active form. It is resistant to cartilage-derived inhibitors and to alpha 2-macroglobulin as well as to synthetic and natural inhibitors of serine-, thiol- and carboxylproteinases . It is inhibited by a chelating agent, 1,10-phenanthroline and thiol compounds at relatively high concentrations, and therefore is probably a metalloproteinase. The enzyme degrades type V collagen, types I and II denatured collagen (gelatin), and casein in addition to cartilage proteoglycan, but not bovine serum albumin, myoglobin, fibrinogen, elastin or native collagen types I, II, III, and IV. These findings suggest that the Yoshida sarcoma may degrade cartilage matrix in vivo by means of a secreted, active, inhibitor-resistant enzyme.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Nuclei isolated from Yoshida sarcoma cells had activity for conversion of dGTP dependent on DNA synthesis. The ratio of nucleotide generation/generation + incorporation was 0.4 +/0- 0.1, indicating that approx. 40% of the incorporated dGMP was excised. Two lines of evidence indicated the dependence of this activity on DNA synthesis. (1) The activity was observed only in the presence of ATP, which is essential for nuclear DNA synthesis. (2) Inhibitors of DNA synthesis, such as N-ethylmaleimide, aphidicolin, spermine and KCl, also inhibited ATP- or DNA synthesis-dependent dGMP generation. Although nuclei contain nucleoside triphosphatase (N-nucleotidase), this enzyme was not involved appreciably in DNA synthesis-dependent dGMP generation. The reason for this was explained by the following findings. (a) Inhibitors did not decrease dGMP production in the complete absence of DNA synthesis. (b) Inhibitors did not inactivate N-nucleotidase to the same degree as they inhibited DNA synthesis-dependent dGMP generation. (c) Addition of ATP reduced dGMP hydrolysis catalyzed by N-nucleotidase. (d) GDP has no appreciable effect on DNA synthesis-dependent dGMP generation, but had a diluting effect on dGMP production catalyzed by N-nucleotidase. These results show that the pathway of dGMP generation in isolated nuclei was switched on addition of ATP from a N-nucleotidase-catalyzed one to a DNA polymerase-exonuclease-catalyzed one.
The relative delays of Yoshida sarcoma (YS) tumor induction were used as indicator for the immunosuppressive potential caused by the subcutaneous infection of Sprague-Dawley rats with approximately 10(7) TCD50 HSV-2. The tumor formation is clearly accelerated and the number of tumors is increased as compared to sham injected rats. The impairment of immunity is at its maximum when the virus and the YS cells are applied simultaneously, whereas virus given after the tumor is of no consequence. The adoptive neutralization test of Winn showed that the neutralization potential of spleen cells originating from HSV-2 infected donors is decreased from day 8 to day 11 post infection but rturns back to normal a week later. The stimulation of spleen cells with PHA is reduced up to 50% of control values on day 6 to 8 post virus infection but PFC and RFC values are not noticeably affected and neither are the hemagglutination titres. The implications of the immuno-suppressive faculty of HSV-2 for human genital malignancies are discuss.ed.
When Yoshida sarcoma cells were inoculated subcutaneously into the left footpad of Donryu rats, the weight of the left lumbar lymph nodes increased proportionally to the number of the inoculated cells. Resection of primary implants the day after the inoculation of 5 x 10(6) cells failed to rescue the host rats and they died of metastases within 12 days. There was no significant difference in mean survival days between the rats (8.9 days) whose primary implants were resected on the 5th day after inoculation and the control rats (8.6 days) bearing the primary implants. Mitomycin-C, a highly effective drug against Yoshida sarcoma cells, produced many long survivors (over 30 days) in the treated rats whose primary implants were resected the day after inoculation, but failed to do so when resected 5 days after inoculation. All of them died of metastases within 20 days. Based on these results, this present system is discussed for its usefulness as a screening and evaluation model for antitumor agents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.