Effect of gamma-irradiation on lipid content and survival of human amnion cells in culture.

The neutral lipid content of Human Amnion cells in tissue culture, studied by cytophotometry, increases after irradiation with 60Co gamma-rays. Cells having an already elevated lipid content, induced by lipid pretreatments, become sensitized to irradiation as determined by cell survival and electrophoretic mobility studies.

Evaluation of intracellular lipids by standardized staining with a Sudan black B fraction.

The selective staining of neutral lipids in Human Amnion cells in tissue culture was achieved using a particular fraction of the lipid dye, Sudan black B and a standardized staining procedure. The fraction, termed SBB-I, was isolated by thin-layer chromatography. The cytophotometric assessment of intracellular neutral lipids, stained with SBB-I, is described and applied to the study of changes in granulocytic neutral lipids in leukemia.

A "two-objective, one-area" procedure in absorption microphotometry and its application using an inverted microscope.

A 'two-objective, one-area' method and related equations are suggested to measure absorbance of microscopic stained objects. In such work, the measuring field invariably includes an image of the object and some clear area surrounding the image. The total intensity in the two areas is measured photometrically, using two different objectives, and substituted in the equation for absorbance. The equation is independent of the term representing intensity from the clear area and hence the error in the measurement of absorbance is reduced. The limitations of the 'two-objective, one-area' method are discussed and its pragmatic operation described with an experimental setup involving an inverted microscope. The method permits measurement of intensity in a part of a stained cell while the rest of the cell remains in the field of view. The method is applied to measure absorbance in Giemsa stained ascites cells and Feulgen stained liver and Human Amnion cells.

Postirradiation utility of insulin in radiotherapy.

The radiobiological effect of insulin was studied under laboratory conditions to find its utility in radiotherapy. Balb/c mice receiving injections of insulin after irradiation exhibited rapid recovery from radiation effect. This was evident from the data on their life span, organ weights and spleen colony assay studies, carried out under conditions of whole body and partial body irradiation. This trend was absent in mice injected with insulin before irradiation. The results of experiments on E. coli B/r and HA cells irradiated in the presence of insulin under oxic conditions suggest radioprotective effect of insulin. The E. coli B/r cells irradiated in the presence of insulin under hypoxia, however, showed a moderate radiosensitizing effect of insulin.

Motility of splenic cells from normal and fibrosarcoma-bearing mice in agarose assay.

When nonadherent splenic cells from normal and tumor-bearing (mouse fibrosarcoma, MFS) Swiss mice were added to wells made in agarose layers in plastic petri dishes, subpopulations of cells from tumor-bearing mice were seen to migrate out of the wells, whereas those from normal mice did not. The proportion of migratory cells among the lower density (less than 1.057 to less than 1.069 g/ml) cells was larger than that of higher density (1.069 to less than 1.087 g/ml) cells. When the plastic surface underneath the agarose layer was covered with a monolayer of MFS cells, the splenic cells from normal mice also migrated out of the wells. About 20% dead MFS cells were observed in the zone of migration when the migratory cells were from normal mice, and about 30% when the migratory cells were from tumor bearing mice. Apart from revealing the differences between the migratory behavior of splenic cells, the present work also suggests a novel application of agarose methodology in the study of interaction of cytotoxic cells with malignant cells.

Study of mutagenic pollution in Bombay.

Airborne suspended particulate matter (SPM) from seven areas in and around Bombay city were collected over glass fibre filters (0.8 micrometer porosity). The chemicals from the SPM were extracted in dimethylsulfoxide and distilled water and were further tested for mutagenicity by Ames' test using for five mutants of Salmonella typhimurium. Of the seven areas studied, only four exhibited mutagenicity, which was confirmed by dose-response assays using the mutant strain TA 100. The very high mutagenicity observed in central Bombay correlates with the higher incidence of respiratory tract diseases in the resident population.

Use of ascorbic acid in the 51Cr labelling of mouse fibrosarcoma cells.

We have studied and discussed the significance of the use of ascorbic acid in 51Cr labelling of cells. The following two advantages seem credible if cells (mouse fibrosarcoma) in culture are incubated for about 2 h in a medium containing Na2 51CrO4 and then ascorbic acid is added to the medium and incubation continued for ten more minutes: (a) the natural intracellular conversion of Cr6+ to Cr3+ appears to be aided, (b) the incorporation of chromium by cells is higher.

Cytotoxicity of subpopulations of splenic cells from normal and fibrosarcoma - bearing mice towards syngeneic tumour cells.

The nonadherent splenic cells from normal and tumour-bearing (mouse fibrosarcoma-MFS) Swiss mice were divided into 6 subpopulations on Percoll step density gradient and characterised. For the determination of their cytotoxicity towards syngeneic MFS cells and their electrophoretic mobility (EPM), the splenic cell populations were pooled to form 2 broad groups: a lower-density group (density of saline to just less than 1.069 g/ml) and a higher-density group (1.069 to just less than 1.087 gm/ml). In general, the splenic cells from mice bearing 10- to 11-day-old MFS tumours differed in certain characteristics from those of normal mice in that they showed an increase in the following: proliferation, heterogeneity, with appearance of large cells (greater than 70 mu2); cells with a lower density (less than 1.069 g/ml); cells with a lower (less than 0.85 micron/sec/Volt/cm) anodi cEPM. The cytotoxicity studies revealed that: a) the lower-density splenic cells of both normal and tumour-bearing mice were more cytotoxic than the higher-density splenic cells; b) the lower- and higher-density splenic cells of tumour-bearing mice were more cytotoxic than the corresponding cells of normal mice. These findings indicate that the splenic cells of mice with a lower EPM and a lower density are the main contributors of cell-mediated cytolysis of a subpopulation of MFS cells.

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.

[Changes in the vitro membrane potential of cancer cells induced by contact with cytotoxic lymphoid cells]. / Modifications du potentiel de membrane de cellules cancéreuses in vitro sous l'influence du contact de cellules lymphoïdes cytotoxiques.

Plasma membrane potentials have been measured in a cancer cell line at different stages of growth. A chamber has been especially built for pH control of the culture medium during several hours. Individual values spread widely from 14 to 44 mV but low measurements are less frequent after 3 days of culture when the growth rate is at a peak. The same cancer line is grafted serially in syngeneic C 57 bl mice were it induces an immunological sensitization of the lymphnode cells. The effect of such cytotoxic lymphocytes on the membrane potentials of the target tumour cell has been studied after a contact (15 to 90 minutes) too short for any morphological changes to be detectable. There is a decrease in the mean values and a very significant rise in percentage of measurements below 20 mV. No such changes are observed in control experiments where naïve lymphocytes are used. These results are discussed in relation to the hypothesis of an increased permeability of the plasma membrane to ions as an early event in cell mediated cytotoxicity.