Irreversible loss of negative surface charge and loss of colony-forming ability in Burkitt lymphoma cells after x-irradiation

A theory of carcinogenesis based on an analysis of the effects of carcinogens

Carcinogenic stimuli appear to act on target cells (and their daughters) by one or more of three mechanisms. The first is by oxidation of membrane component molecules on the extracellular surfaces of their plasma membranes. The second is by chronic and continuous impingement of electrons on the extracellular surfaces of their plasma membranes and the third is by relocation of predominantly basic molecules to the cytoplasmic surfaces of their plasma membranes. This latter effect in turn causes electrostatic attraction of image charged acidic molecules to the extracellular surfaces to balance the transmembrane charge of the target cells. Each of the above mechanisms results in a condition of increased electronegativity of the extracellular surfaces of plasma membranes of the target cells and their daughters. A theory of transformation is advanced based on the above related modes of action and it is used to explain some previously unexplainable properties of tumors.

Osteosarcoma with multiple intramuscular metastases. A case report

A 21-year-old man with an osteosarcoma in the proximal tibia was treated by amputation, radio- and chemotherapy. Besides pulmonary metastases, intramuscular metastases repeatedly developed. Cell culture studies of pulmonary and muscular tumors showed different sensitivity patterns for cytostatic drugs; the therapy may have selected different subpopulations of the primary tumor.

Radiobiological effect of heparin in Swiss mice, human amnion cells and E. coli B/r irradiated with Co60 gamma-rays

The radiobiological action of Heparin was investigated using the test systems E. Coli B/r, Human Amnion (HA) cells and Swiss mice. The Heparin treatment of these systems effected following changes in their response towards irradiation with Co60 gamma-rays: (a) more sensitization of E. coli B/r in hypoxic than in oxic condition, (b) no significant modification for HA cells in oxic condition but their sensitization under hypoxia, (c) larger recovery of anodic electrophoretic mobility of irradiated HA cells, (d) increased life span and smaller reduction in the splenic and thymus weights of irradiated Swiss mice. It seems, therefore, that Heparin, a natural molecule of animal world, possesses the potentiality to modify radiation response of living systems and may find useful application in radiation therapy.

Radiosensitivity of human B-lymphocytic lymphomas in vitro

The radiosensitivity of four human B-lymphocytic lymphoma cell lines has been studied. For all lines the Do values were in the range 1.3 to 1.8 Gy. None of the survival curves had an appreciable shoulder. The extrapolation numbers varied in the range 1.0 to 1.2. Thus, the cell lines had a low capacity to accumulate sublethal damage. Furthermore, split dose experiments showed that no line had the capacity to repair sublethal damage. Taken together with earlier published experimental and clinical observations the results indicate that the use of an increased number of fractions in radiotherapy of B-lymphocytic lymphomas might be of great benefit to the patients. A schedule with an increased number of fractions will probably be as efficient in killing the tumour cells as previously used schedules but the tolerance of adjacent normal tissue will probably increase.

Calcium-dependent process in reduction of cell surface charge after x-irradiation

The electrophoretic mobility (EPM) of rat erythrocytes and cultured melanoma cells decreased with time after X-irradiation in the presence of calcium at concentrations higher than 10 (-5) M. At 37 degrees C, the presence of calcium for the first 20 min of exposure was suffcient to induce the EPM reduction, and Ca 2+ administration subsequent to Ca 2+ -free incubation for 30 min following irradiation had no effect on EPM. At lower temperatures, from 10 down to 20 degrees C however, the effect of calcium on the reduction of EPM decreased drastically. If the cells were kept Ca 2+ -inonophore A23187 also induced to decrease in EPM only in the presence of Ca 2+. These results revealed the transitory existence of membrane condition reactive to extracellular Ca 2+ immediately after X-irradiation, which can be postponed at low temperatures. The reduction of EPM by Ca 2+ -ionophore might suggest that the influx of Ca 2+ is a step in the reduction of EPM after X-irradiation.

Surface charge in foreign body carcinogenesis

The importance of surface charge in foreign body carcinogenesis was evaluated by implanting in C3H/HeJ male mice, bipolar polystyrene thermoelectrets formed in variously charged electrical fields. Charged electrets had tumor rates similar to control groups. The cumulative probability of tumor development was highest in the charged electret group being 0.58 at 133 weeks after implantation. The tumor rate for all charged electrets was 27% as compared to 17% and 6% for the control groups. The latent period of tumor induction varied little between groups and averaged approximately 700 days. No conclusions regarding the tumorigenic effect of electropositive versus electronegative sides of the electret were made although the majority of tumors arose on the electronegative (body) side of the electrets. An occasional tumor (2/25) arose on both sides of a single electret. The antigenicities of tumors tested by excise and challenge techniques were weak. The immunologic relationship between top and bottom growing tumors on a single electret could not be adequately determined because of the weak antigenicity.

Translocation of hyaluronic acid in cell surface of cultured mammalian cells after x-irradiation and its recovery by added adenosine triphosphate

To investigate the mechanism of radiation-induced decrease in cell electrophoretic mobility and its recovery by added adenosine triphosphate, specific enzymes and buffer solutions of different ionic strength were utilized. Decrease in the mobility of irradiated cells was detected only with the buffer solution of ionic strengths higher than 0.100. In this range of ionic strengths, removal of hyaluronic acid from cell surface by hyaluronidase had no effect on the electrophoretic mobility of irradiated cells, while the enzyme treatment resulted in 27% mobility reduction in non-irradiated cells. The removal of sialic acid and chondroitin sulfate by their specific enzymes resulted in the similar decrease in mobility either in irradiated and non-irradiated cells. These results suggest that the X-ray induced translocation of hyaluronic acid from the peripheral zone of O--7.5 A into the deeper zone of about 10--17 A, if we use the Debye-Hückel's thickness of ion atmosphere for an approximate estimate of effective depth of electrokinetic plane of shear. Hyaluronic acid reappeared to the peripheral zone by the subsequent incubation after small dose irradiation, or by the addition of 1 mM adenosine triphosphate with Ca2+.

Small amount of concanavalin A modifies radiation-induced alteration in cell-surface charge depending on its binding condition

Cell electrophoretic mobility of cultured melanoma cells or rat erythrocytes decreased with time after X-irradiation. Addition of tetravalent concanavalin A or divalent succinyl-concanavalin A before (not after) irradiation, completely blocked the mobility reduction in greater concentrations than 5 mug/l. At 5 mug/l only 3.7 - 10(3) concanavalin A molecules bound to receptors per cell, while 4.18 - 10(7) molecules/cell bound at saturating concentrations. Preincubation with concanavalin A at 37 degrees C was effective even when the cells were treated with alpha-methylmannoside immediately after irradiation. At low temperature, however, concanavalin A was not effective despite a sufficient amount of bound 125I-labelled concanavalin A. Treatment with alpha-methylmannoside following the binding of concanavalin A at 37 degrees C before irradiation inhibited the concanavalin A effect depending on temperature. The residual amount of bound lectin could not account for the temperature dependence. The amount of sialic acid (the main charged substance) was not altered by X-irradiation with or without the lectin. Divalent succinyl-concanavalin A was also effective in blocking the radiation effect on electrophoretic mobility. These results seem to suggest that binding of a very small amount of concanavalin A without causing cell agglutination or clustering of its receptors, induces some alteration in the conformation of receptor glycoprotein, which blocks the internalization of acidic sugar residues by subsequent irradiation.