The survival responses to 250 kVp X-irradiation of 20 different exponentially growing human colon tumor lines have been described using the linear-quadratic equation of cell survival. Because some of ...these tumor lines (6/20) showed statistically significant increases in colony forming efficiency (CFE) when feeder cells (FCs) were added (10(5) FCs/60 mm dish), radiation survival parameters were determined for all 20 tumor lines with and without added feeder cells. In neither FC independent nor FC dependent lines did addition of FCs significantly affect any of the derived radiation survival parameters, including the alpha and beta inactivation constants, the mean inactivation dose (D, Gy), or the surviving fraction of cells at 2 Gy (S2). The average alpha, beta, and S2 values for these 20 human colon cancer cell lines with added feeder cells were: 0.281 Gy-1, 0.0711 Gy-2, and 0.443. A cumulative frequency distribution plot of the mean inactivation dose (D) which includes other published radiobiological data on human colon cancer cell lines (N = 26) indicates that the D50 value is 2.17 Gy.
Several laboratories have introduced the lacZ gene into 9L cells to improve the usefulness of this already popular rat brain tumor model. However, these laboratories were not concerned about possible ...changes in the phenotypic characteristics of the 9L cell line which can be induced by the selection of lacZ-expressing clones. Here, we describe a method for introducing the lacZ gene into 9L cells without selective cloning. The 9L parent cells (passaged the same number of times) and 9L/lacZ cells were compared in a number of tests and found to have the same phenotype. Specifically, they had the same sensitivity to radiation from external gamma or internal beta radiation, the same growth rates with or without frequent media changes and the same patterns of growth in rat brain. We demonstrated that the 9L/lacZ cells could be sorted from dissociated tumors by flow cytometry and the percentage of nonmalignant versus malignant cells determined. These percentages were variable from rat to rat. The colony-forming efficiency could be determined on the basis of whole tumor or, by using the percent of lacZ-positive cells, on the basis of malignant cells in a tumor. These novel approaches should render the 9L tumor model even more useful.
Tube bulging by electromagnetic forming using a new type of sheet spiral coil is proposed. Under various working conditions the effects of profile and forming efficiency are experimentally ...investigated. The number of turns of the coil, the length of the coil, the charged energy and the capacity of the capacitor bank are used as experimental parameters. The forming mechanism is clarified. As the number of turns of the coil increases, the amplitude of current waves and the period of current decrease. The bulge height is maximized within the range of number of turns of coil between 18∼30. The deformation of the tube bulge is reduced when the coil length increases. The fewer the turns of the coil and the smaller the capacity of the capacitor bank, the higher the forming efficiency. The forming efficiency becomes maximum at the current frequency of about 5kHz.
The colony-forming efficiency (CFE) of primary human tumor cells cultured in the adhesive-tumor-cell culture system (ATCCS) using Ham's F12 (F12) or Eagle's minimum essential medium, alpha ...modification (alphaMEM) and culture medium supplemented with either swine, equine or bovine sera were compared. AlphaMEM supplemented with equine serum provided the highest CFE of the combinations. The CFE increase due to the change from F12 to alphaMEM was approximately 5-fold, and the increase due to the change in serum from swine to equine was approximately 2-fold. Cytokeratin staining showed that this increase was not due to fibroblast growth. The high-average CFE with alphaMEM, approximately 3%, means that an inoculum of only 2 X 10(3) cells is needed to achieve formation of approximately 65 colonies in control cultures, thereby increasing the performance of this system when used in a chemosensitivity assay.
Pyrroxamide N-(1-hydroxymethyl-2,3-dihydroxypropyl)-2,2,5,5-tetramethyl pyrrolidine-1-oxyl-3-carboxyamide is a newly tested nonionic monomeric nitroxyl compound with demonstrated effectiveness for ...MRI contrast enhancement at doses as low as 10(-3) M. Pyrroxamide and its hydroxylamine metabolic derivative were tested in concentrations from 10(-9) to 10(-2) M with a battery of cytotoxic and mutagenic assays using mammalian Chinese hamster ovary cells. Loci-specific mutation induction was examined at the hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and the Na+/K+ ATPase loci, both in the presence and absence of a liver microsomal metabolic activating mixture (S-9 mix). Cell survival and induction of sister chromatid exchanges also were studied. All tests yielded negative results indicating that pyrroxamide and and hydroxylamine derivative were both noncytotoxic and nonmutagenic at the doses tested.
TN-368 cells were seeded at$10^6 per flask$in TNM-FH medium adjusted to a variety of pH levels which ranged from approximately 5.9 to 6.8. In general, growth was similar from pH 6.2 to nearly 6.7. ...The medium pH increased with time in culture to a maximum near 7.0 for all pH levels. Similar results for growth and pH increase were also obtained when the cells were plated at densities of 104and$10^5 per flask$. Both the fraction of attached cells and the relative intensity of attachment increased with seeding pH. Cells seeded near pH 6.7 or above frequently required vigorous procedures such as trypsinization to detach them. DNA synthesis was measured and found to be similar for cells seeded in medium between pH 6.2 and 6.7. Colony forming efficiency increased from approximately 27% at pH 5.9 to 39% at 6.2, remained in the region of 40% between 6.2 and 6.7 with a peak of 48% at 6.6, and plunged abruptly to a few percent just above 6.7 and was near zero above 6.8. Colony morphology was optimal near pH 6.6.
A rat brain tumor model was prepared by stereotactically implanting 4×104 cultured 9L tumor cells in the cerebral hemisphere. The tumor bearing rats exhibited weight loss after two weeks, developed ...neurological symptoms several days later and died 19-20 days post-implant. Tumor take was 100% and the lethal tumor weighed 279 mg. The tumors had a doubling time of 39.5 hours. Cell kinetic parameters determined by PLM curve analysis 14-16 days post-implant were: TC-19.3 hrs.; TG1-8.6 hrs.; TS-7.6 hrs.; TG2-2.9 hrs.; and TM-0.2 hrs. The growth fraction was 0.55 and the cell loss factor was 0.24. The effectiveness of combined modality therapy on this model was analyzed in terms of survival, tumor size and colony forming efficiency. BCNU administered on day 16 post-implant produced an ILS of 122% while treatment on day 10 produced an ILS of only 60%, which corresponded to a 3-3.5 log cell kill and 2-2.5 log cell kill, respectively. Microsurgical removal of tumors on days 13 and 16 post-implant produced an ILS of 28% (1 log cell kill) and 56% (2 log cell kill). Surgery performed more than 3 days before or after BCNU therapy was less effective than BCNU alone on day 16. An ILS of over 200% (< 7 log kill) was achieved when BCNU was given 1 hr. before or 1 hr. and 12 hrs. after surgery performed on day 16. BCNU was not effective when administered during the surgical procedure. Cell kinetic parameters of both perturbed and unperturbed tumor cell populations can be used to design even more effective combined modality therapy.
This investigation was designed to determine whether cell death plays a role in the antiproliferative action exerted by polyamine synthesis inhibitors. To estimate the rate of tumor cell death, we ...measured the loss of 125I from mice harboring Ehrlich ascites tumor cells in which DNA was labeled with 5-125I-iodo-2'-deoxyuridine. DL-alpha-difluoromethylornithine (0.85 mumoles/g body weight/6 h), and enzyme-activated irreversible inhibitor of ornithine decarboxylase, and methylglyoxal-bis(guanylhydrazone) (45 nmoles/g body weight/6 h), an inhibitor of S-adenosylmethionine decarboxylase, were both found to increase the rate of 125I excretion. Our data suggest that these polyamine synthesis inhibitors provoke an increase in the rate of tumor cell death beyond that normally occurring during growth, methylglyoxal-bis(guanylhydrazone) being considerably more potent than DL-alpha-difluoromethylornithine. These in vivo data were corroborated by a study where the host-mediated responses did not have to be considered. Thus, Ehrlich ascites tumor cells were adapted for suspension growth in culture and treated with methylglyoxal-bis(guanylhydrazone) or DL-alpha-difluoromethylornithine. The growth kinetics and the colony forming efficiency of the drug-treated cells clearly show that polyamine synthesis inhibitors not only slow the growth rate but also cause an increase in tumor cell death.
PDF
