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PubMed1963

STUDIES ON THE ISOLATION OF METAPHASE CHROMOSOMES.

A method for the isolation of metaphase chromosomes from mouse L1210 leukemia cells has been developed. Cells, arrested at metaphase with colchicine, were exposed to hypotonic solution and the pH was then adjusted to 5.6 to stabilize the chromosomes. The metaphase figures were subsequently disrupted and the chromosomes isolated by a series of differential centrifugations in sucrose. The isolated chromosomes were well preserved, as judged by morphological criteria. The effect of various enzymes and chemical agents on the isolated chromosomes was studied. Chymotrypsin, trypsin, and deoxyribonuclease caused a marked disintegration of the chromosomes, whereas treatment with pepsin and ribonuclease induced no significant morphological alterations.

Centrifugation↗
PubMed1964

POLYOMA VIRUS GENETIC MATERIAL IN A VIRUS-FREE POLYOMA-INDUCED TUMOR.

The DNA-agar technique for homology studies was used to investigate of the viral genetic material. Complemetary found between the polyoma DNA and the DNA of several mammalian species. The increased complementarity of the polyoma DNA to the DNA of polyoma-induced tumor reflects an increased frequency of common poly-nucleotide sequences in the tumor DNA.

Animals↗
PubMed1964

INDUCTION OF LAMBDA-BACTERIOPHAGE IN ESCHERICHIA COLI AS A SCREENING TEST FOR POTENTIAL ANTITUMOR AGENTS.

A simple, rapid, quantitative test procedure to measure induction of phage production in lysogenic Escherichia coli K-12 (lambda) was described. This test was used in a study of 209 substances, including antibiotics, pyrimirines, purines, alkylating agents, thiols, amino acids, vitamins, and miscellaneous compounds. Minimal inducing concentrations for the 26 (12.5% of total tested) substances found to be effective inducing agents, as well as a listing of the inactive compounds, are presented. Since 21 of the 26 active agents reportedly have antineoplastic activity in rodent tumor systems, it was concluded that the induction test may provide a useful screen for the detection of potentially useful antitumor compounds.

Alkylating Agents↗
PubMed1964

SYSTEM FOR DETECTING INDUCERS OF LYSOGENIC ESCHERICHIA COLI W1709 (LAMBDA) AND ITS APPLICABILITY AS A SCREEN FOR ANTINEOPLASTIC ANTIBIOTICS.

Studies were conducted to determine conditions of maximal sensitivity for a test system designed to detect chemical inducers of phage production in the streptomycin-dependent, lysogenic Escherichia coli strain W1709(lambda). This strain was found to be induced by all antibiotics previously reported to be inducers of E. coli K-12(lambda). However, the system employing W1709(lambda) proved superior for screening fermentation filtrates because its growth, in contrast to that of K-12(lambda), was not stimulated during the induction period by filtrate nutrients. Thus, misleading high phage counts, which accompany cell growth stimulation, were not produced by filtrates devoid of inducing activity. The inducing capability of 95 fermentation filtrates, each containing an unidentified antibiotic(s) inhibitory for one or more transplanted rodent tumors, was determined in the W1709(lambda) system. A low incidence of inducers was found among inhibitors of sarcoma 180, adenocarcinoma 755, solid myeloid leukemia C1498, and adenocarcinoma of the duodenum in the hamster. However, seven of eight filtrates active against leukemia 1210 had induction capability. From a screen of actinomycete culture filtrates, 28 of the first 1,000 were identified as producers of induction activity. Thus far, of the nine cultures from this group that were subjected to examination, eight demonstrated at least presumptive evidence of antineoplastic activity.

Anti-Bacterial Agents↗