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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using cells from our tissue culture of human melanoma cell line Na 11, we transplanted 1 X 10)6) tumor cells sc into athymic nude mice. Tumors appeared after a latent period of 4-10 days; when they reached a mean volume of 100 mm3 we irradiated them with various doses of X-rays. Some tumors were irradiated while the mice were still alive; others were treated 10 minutes after the animals had been asphyxiated with nitrogen. All irradiation was done in the presence of oxygen. These tumors were excised, and cell suspensions were prepared; the cells formed colonies with a mean plating efficiency of 29%. In another series of experiments, we irradiated tumor cells in vitro 2 hours after excision, when most cells were fixed and presumably oxygenated. We then calculated survival curves for the tumor cells irradiated under these three conditions and found an average anoxic cell fraction of 85%, which was much higher than that reported in many other tumor systems. We explored several possible explanations for this phenomenon.
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PMID:Survival curve of a human melanoma in nude mice. 86 46

We are using three correlated approaches in tissue culture to develop procedures for distinguishing between histologically similar tumors and to develop distinctions that we hope can be correlated with a favorable outcome or with recurrence of more serious disease. Our procedures involve study of the growth of resected tumor tissue in a three-dimensional matrix of collagen-coated cellulose sponge. Using bladder cancer cell lines we are also studying the patterns of cytotypic zonation that appear in response to prolonged exposure to continuous gradients of oxygen tension and of temperature. Finally, we are using vitamin A and modifiers of cyclic adenosine 3':5'-monophosphate as molecular probes to alter the morphological expression of tumors in matrix and in gradient cultures. We have studied over 80 specimens of clinical cancer in matrix culture. Tumors of similar histopathology grow with distinctly different architecture in the matrix of collagen-coated sponge. We must now determine whether these patterns in vitro can be correlated with the course of individual patients.
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PMID:Development of tissue culture procedures for predicting the individual risk of recurrence in bladder cancer. 87 14

The carotenoid crocetin (earlier found to increase relative growth of Walker 256 tumor cells and their radiosensitivity), is shown to increase the relative growth of normal Sprague-Dawley rat muscle derived cells in vitro, presumably by increasing oxygen transport.
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PMID:Increased relative growth rate of normal rat cells in vitro with crocetin. 89 3

Biological information suggests that high LET radiations could be used advantageously in radiation therapy. The radiation responses of cells and tissues are described in general terms with respect to the following aspects of high LET radiations considered for therapeutic use: spatial distribution of biological effect, oxygen enhancement of cell lethality in mixed LET radiation beams, dependence of oxygen enhancement of cell lethality upon the microscopic distribution of energy loss, gain factors due to relative biological effectiveness alone, and recovery from sublethal cellular damage. It is concluded that there is no single advantage to the use of high LET radiations in radiation therapy, but that combinations of advantages may exist for different radiations and different tumor-normal tissue combinations. Cases in which inverse gain factors occur are to be avoided.
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PMID:Biological aspects of high LET radiation therapy. 91 64

Autoradiographic study was made on 24 cases of uterine cervical tumor, including 22 cases of squamous cell carcinoma, using a technique of in vitro labeling of surgical specimens with tritiated thymidine (3H-TdR) under hyperbaric oxygen. Labeling index of the cervical cancer ranged from 8.7 to 30.4% and was well correlated with the histological subtypes (spinal, transitional, and basal cell types). The upper limit of the growth fraction was also estimated from the general relationship between phase lengths. The necessity of sufficient oxygen tension for the S-phase cells to effect synthesis of DNA was stressed.
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PMID:Measurement of tritiated thymidine labeling index by incubation in vitro of surgically removed cervical cancer. 91 53

Mice, carriers of the Ehrlich ascites carcinoma, were exposed to a fractionated whole-body irradiation with four times 750 R. Before resp. after each exposure, an ozone-oxygen mixture was intraperitoneally injected. In other cases, the ozone-oxygen mixture was given without irradiation. Ozone had no essential effect upon the transplantation capacity neither in irradiated ascites cells nor in cells not exposed to radiation. Ehrlich ascites tumor cells, transplanted into a subcutaneous air-pocket under the abdominal skin of the mouse, developed a solid tumor and a fluid accumulation without cells. A diminution of the fluid was brought about by means of a fractionated local irradiation with five times 200R, by a secondary treatment with ozone and also by ozone alone. Evidence of damage to the tumor cells, however, is only to be produced by investigations into the metabolism and reproductive capacity of these cells.
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PMID:[Animal experiments on ozone therapy of non-irradiated and irradiated tumors. II. Ehrlich ascites carcinoma in vivo]. 94 58

Continuing an earlier publication in which the growth of spontaneous mammary carcinomas in female mice of a C3H inbred strain was described, in the present paper the growth rate is expressed by a mathematical function, and is adapted by electronic data processing to the experimental values of 60 tumors classified into seven "growth types". For mathematical description the tumors were conveniently assumed to have a spherical shape, and the main reason for the reduction in volume increase with increasing tumor size was thought to be insufficient supply with oxygen and the essential nutrients S. Including the experimental data of all carcinomas investigated, the minimum concentration of S necessary for mitotic activity of the tumor cells was calculated to be 65% of the normal level. As the average for all the tumors investigated, a time of at least 33 hrs is required for the tumor volume to double.
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PMID:[Studies for a mathematical model of the proliferation kinetics of mammary carcinomas by means of electronic data processing (author's transl)]. 96 3

It is suggested that anoxic conditions may enhance the transformation of tumor cells to increase production of tumor angiogenic factor. The theory of oxygen diffusion into a spherical mass is used to calculate an upper bound for the critical size at which anoxia begins to develop in the center of an avascular clone of tumor cells. The predicted size is in line with experimental observations of the maximum size of avascular tumors.
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PMID:A possible mechanism for enhancement of increased production of tumor angiogenic factor. 97 65

Experiments with Chinese hamster cells have shown that neutron irradiation does not result in repair of potentially lethal damage (PLD), i.e., that which can be influenced by changes in environmental conditions following irradiation. Since PLD is presumed to be repaired in tumors but not in normal tissues, this absence of differential sparing of tumor cells relative to normal tissues--a feature characteristic of irradiation with x rays--represents an advantage of neutrons in addition to their reduced oxygen effect. At a given dose, the difference in relative biological effectiveness (RBE) between tumors and normal tissues corresponds to a 5% increase in tumor dose with no concomitant increase in dose to normal tissues, which could be significant in cancer therapy.
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PMID:Repair of potentially lethan radiation damage: comparison of neutron and X-ray RBE and implications for radiation therapy. 98 75

Incubation of Chinese hamster ovary cells and KHT murine fibrosarcoma tumor cells in the absence of oxygen with 1-[2-14C]nitro-1-imidazolyl)-3-methoxy-2-propanol, one of the most effective radiation sensitizers of hypoxic cells, results in the preferential reduction of 1-[2-14C]nitro-1-imidazolyl)-3-methoxy-2-propanol. The radioactivity associated with the acid-insoluble precipitate from cells incubated in nitrogen is about four times higher than that of cells incubated in air. When aqueous extracts of tissues of a C3H mouse bearing the KHT tumor, after i.p. injection with 1-[2-14C]nitro-1-imidazolyl)-3-methoxy-2-propanol, are analyzed, a reduction product is found in relatively higher yields in the tumor than in normal tissues. The relative radioactivity in the pellet from the tumor homogenate is also high in comparison with those of most normal tissues. These results provide suggestive evidence for a higher degree of hypoxic in the tumor than in most normal tissues. The formation of reduction products and their subsequent binding to macromolecules may explain the preferential toxicity of nitro compounds to mammalian cells under hypoxia conditions. These results suggest that some nitro compounds may be useful for the treatment of tumors having a high fraction of hypoxic cells even in the absence of radiation.
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PMID:Hypoxia-dependent reduction of 1-(2-nitro-1-imidazolyl)-3-methoxy-2-propanol by Chinese hamster ovary cells and KHT tumor cells in vitro and in vivo. 98 41


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