0000000000603132
AUTHOR
Leoni A. Kunz
Oncogene-Associated Growth Behavior and Oxygenation of Multicellular Spheroids from Rat Embryo Fibroblasts
It is now well documented that naturally occurring and experimentally induced tumors develop by a multistep process involving different stages such as unlimited growth, metastasis, and invasiveness. There is much evidence that malignant transformation involves activation of oncogenes and/or loss of suppressor genes (= anti-oncogenes). The former fundamental class of genes, including the ras and myc families, are associated with cell proliferation and differentiation and may mediate tumor initiation, promotion and progression (for reviews see: Spandidos, 1985; Spandidos and Anderson, 1987, Weinberg, 1989).
EFFECT OF MICROENCAPSULATION ON OXYGEN DISTRIBUTION IN ISLETS ORGANS
In islet transplantation, limitation of oxygen supply may restrict graft function, particularly when encapsulated tissue is used. Therefore, oxygen tensions (PO2) in isolated islet organs (Brockmann bodies) of Osphronemus gorami were measured. In a thermostatically (37 degrees C) controlled measuring chamber, PO2 values were recorded at subsequent microelectrode positions on a radial track toward the center of the organ. In 2 independent groups, we studied the effect of fluid convection (n = 12) and microencapsulation (n = 12). In both groups, sigmoidal PO2 profiles were found, which permit differentiation in an oxygen-depleted zone surrounding the surface, a steep decline inside the tissue…
Interrelationship Among Morphology, Metabolism, and Proliferation of Tumor Cells in Monolayer and Spheroid Culture
Previous investigations have indicated a positive correlation between the proliferative and metabolic activities of tumor cells in monolayer culture (Freyer et al., 1984; Freyer and Sutherland, 1985; Walenta and Mueller-Klieser, 1987). On the other hand, no difference in the local oxygen consumption has been found between highly proliferating outer cell areas and non-proliferating inner cellular regions in multicellular tumor spheroids (Mueller-Klieser, 1984, 1987). Therefore, the interrelationship among metabolism, proliferation, and cellular morphology was investigated systematically in tumor cells both in monolayer and spheroid culture.