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Biomedical subjects

C W Song

Publications and source records attributed to C W Song.

At least 163 records · Page 9Linked to original sources
PubMed1978

Tumor cell respiration following irradiation.

Oxygen consumption rates for mouse mastocytoma cells examined from 3 to 4 hours after x-irradiation with 250-2000 rads were consistently higher than controls. Cyclic fluctuations in oxygen consumption per cell were dose-dependent; peaks in consumption were generally greater in magnitude and occurred later in time with increasing dose. The cyclic response in consumption is probably due to cell synchronization effects, while the overall higher respiration rates of irradiated cells may reflect increased metabolic activity in response to radiation damage. Oxygen consumption rates for the total cell population were cyclic after 250 and 500 rads, but declined steadily after 1000 or 2000 rads; oxygen consumption rates tended to be lower than controls, especially 12-24 hours postirradiation. Differences between cellular and population oxygen consumption rates reflect changes in cell number after irradiation. It is suggested that postirradiation reoxygenation kinetics in solid tumors may result from changes in tumor oxygen demand.

Animals↗
PubMed1978

Tumor reoxygenation and postirradiation vascular changes.

Postirradiation reoxygenation kinetics of the Walker 256 carcinoma were examined and related to radiation-induced changes in tumor vascular functions. Changes in the hypoxic cell component of irradiated Walker tumors may occur by two mechanisms. Reoxygenation of previously hypoxic cells may be due to an increased rate of blood flow in some parts of the tumor. Hypoxic tumor cells may also be eliminated by cell death due to prolonged or severe hypoxia in other parts of the tumor as a result of substantial damage to the tumor vasculature as seen in radiation-induced changes in vascular volume and blood vessel permeability. Reoxygenation of experimental tumors following single, massive doses of radiation may be different from that occurring in human tumors during the course of multifraction radiotherapy.

Animals↗
PubMed1978

Cytotoxic effect of 5-thio-D-glucose on chronically hypoxic cells in multicell spheroids.

The effect of 5-thio-D-glucose on chronically hypoxic cells in the multicell spheroids of Chinese hamster V79 cells was investigated. The radiation survival curves of spheroid cells indicated that most of the chronically hypoxic cells in the spheroids could be eliminated by incubating the spheroids with 5-20 mM of 5-thio-D-glucose or 17 hours. Histological studies also demonstrated that 5-thio-D-glucose preferentially kills the hypoxic cells located in the inner part of the spheroids.

Cell Survival↗
PubMed1978

Elimination of hypoxic protection by 5-thio-D-glucose in multicell spheroids.

The effect of 5-thio-D-glucose on oxic and hypoxic V79-171 Chinese hamster cells was studied in vitro with single cells and multicell spheroids. At concentrations that were not toxic to oxic cells, this compound killed hypoxic cells with a D0 of 1 hr with a 5 mM concentration and more rapidly at 10 mM beginning 2 hr after incubation at 37 degrees. 5-Thio-D-glucose also sensitized hypoxic cells to radiation and protected oxic cells from radiation damage. Multicell spheroids irradiated after incubation with the compound demonstrated increased radiosensitivity, although the relative contribution of cytotoxicity and hypoxic cell sensitization could not be evaluated. Spheroid reoxygenation by decreased cell respiration was determined not to be a contributing factor, suggesting that the spheroid-sensitizing effect was due to drug effects on hypoxic cells. The dramatic increase in multicell spheroid radiosensitivity that resulted from treatment with 5-thio-D-glucose suggests that this compound may be used to increase the effectiveness of radiotherapy by eliminating hypoxic protection.

Cell Survival↗
PubMed1977

Radiotherapy in the postoperative treatment of operable cancer of the breast. Part II. A re-examination of Stjernswärd's application of the Mantel-Haenszel statistical method. Evaluation of the effect of the radiation on immune response and suggestions for postoperative radiotherapy.

A re-examination of the statistical methods used to develop the claim that radiation postoperatively decreases survival was carried out. This study demonstrates that a) when correct figures are used, statistical significance is not demonstrated, i.e. there is not statistically significant evidence that irradiation of the peripheral lymphatics and/or chest wall following mastectomy has a deleterious effect on survival, b) the use of the Mantel-Haenszel procedure was inappropriate for the purpose for which it was used. A survey of the available evidence fails to substatiate the claim that the immunological system effects of local irradiation relate in any way to decreased survival. Recommendations for the use of irradiation postoperatively in the treatment of breast cancer are made.

Adult↗
PubMed1977

The combined effect of radiotherapy and neuraminidase-treated tumor cells on 3-methylcholanthrene-induced fibrosarcoma.

Active immunotherapy with tumor cells treated in vitro with Vibrio cholerae neuraminidase (VCN) plus mitomycin C augments the antitumor effects of local x irradiation in the treatment of firmly established methylcholanthrene-induced fibrosarcoma, MC-43, in syngeneic C3H/HeJ female mice. In most experiments, the inhibition of tumor growth was greater when VCN-treated tumor cells were combined with local irradiation than could be achieved with VCN-treated tumor cells or local irradiation alone. Even in those experiments in which the immunotherapeutic effect of VCN-treated cells was negligible, the combination of radiotherapy and immunotherapy appeared to be greater than irradiation alone. Similarly, total permanent regression of established tumors occurred more frequently after combined therapy than after immunotherapy or radiation therapy alone.

Animals↗
PubMed1977

Intracisternal A and bar-shaped particles in murine neuroblastoma C 1300.

Transplantable murine neuroblastoma C 1300 was studied ultrastructurally at varying time intervals ranging from 2 hours to 40 days before and after X-irradiation. Following X-irradiation, 2000 and 4000 rads in a single dose, the uniformly small tumor cells became progressively enlarged multinucleated and degenerated, starting at one to two days. At five to seven days, the uni- and multinucleated giant cells predominated over the small tumor cells, while the giant cells progressively disappeared therafter and the small tumor cells predominated over the giant cells at 10 to 14 days. The giant cells contained abundant subcellular organelles and the X-irradiated tumor cells apparently continued to produce the organelles until they degenerated. Two types of cytoplasmic particles, intracisternal A and bar-shaped, were observed in the tumor cells. The intracisternal A particles occurred in almost all non-irradiated tumor cells though their number varied considerably from cell to cell, while they were observed less frequently in the radiation-induced giant cells probably due to a dilution effect rather than an actual numerical decrease. The bar-shaped particles, hitherto undescribed in the neuroblastoma, were 23 nm in diameter, variable in length and occasionally tubular. They occurred only in degenerating cells regardless of X-irradiation but were encountered more frequently in irradiated tumors than in non-irradiated ones. It is suggested that they may represent an unknown degenerative product of cytoplasm and/or nucleus rather than virus particles, despite their morphological resemblance to certain virus particles.

Animals↗
PubMed1977

Cytotoxic and radiosensitizing effects of 5-thio-D-glucose on hypoxic cells.

The effect of 5-thio-D-glucose on the viability and radiosensitivity of P815-X2 mouse mastocytoma cells was studied in vitro. By itself, this compound is specifically cytotoxic toward hypoxic cells; moreover, it sensitizes hypoxic cells to irradiation while it protects aerobic cells from radiation damage. These features, together with its low toxicity, suggest that 5- thio-D-glucose may be useful adjuvant to radiotherapy

Cell Survival↗
PubMed1977

Combined radiotherapy and Corynebacterium parvum treatment of a murine fibrosarcoma.

A single dose of Corynebacterium parvum (Cp) at 70 microgram, 175 microgram or 350 microgram was effective in suppressing the growth of a subcutaneous fibrosarcoma and occasionally in inducing complete regression and in prolonging the survival time of C3H/HeJ tumor-bearing mice. A single exposure of x rays at 2,000 rads induced some complete regression, but a higher number of complete regressions was induced by combined x-ray and Cp treatment. In the combined x-ray and Cp treatment, Cp given on the same day immediately after x irradiation was best. When 70 microgram of Cp was given a few days before x rays, the intravenous and intraperitoneal routes were better than the intratumor route of injection.

Animals↗