3.3 Glucose levels in microregions of multicellular EMT6/Ro tumor spheroids

Abstract of the 68th Meeting (Spring Meeting) 6–9 March 1990, Heidelberg

Respiratory gas exchange in the rat spleen in situ and intrasplenic oxyhemoglobin saturation.

Measurements of splenic respiratory gas exchange and of HbO2 saturations in the red pulp of the rat spleen have shown that there are no indications of a reduced intrasplenic O2 availability during normoxia. The present studies provide evidence that, in the normal spleen, the intrasplenic sequestration of red blood cells cannot be explained by an O2 deficiency in the red pulp since the commonly accepted notion of an intrasplenic hypoxia is not true.

Impact of Various Thermal Doses on the Oxygenation and Blood Flow in Malignant Tumors Upon Localized Hyperthermia

Hyperthermia exhibits various direct cytocidal effects (Dickson, 1977; Overgaard, 1977; Suit, 1977). During heat treatment in vivo, several indirect mechanisms enhance the direct cell-killing capacity of hyperthermia. Therefore, the effective use of hyperthermia can overcome some of the well-known problems involved in modern radiation therapy at least in some malignant tumors.

Tumor Blood Flow and O2 Availability during Hemodilution

An insufficient and heterogeneously distributed nutritive blood flow leads to an inadequate and nonuniform supply of O2 and substrates in many solid tumors (Vaupel, 1977, 1979, 1982). This deterioration of the supply conditions, which already occurs in very early growth stages and which is superimposed by a deterioration of diffusive transport during advanced growth stages, is paralleled by a decrease in the therapeutic efficacy of various cancer treatment modalities such as irradiation and chemotherapy with antiproliferative drugs. In the case of anticancer drugs, the efficiency may be reduced by affecting both pharmacokinetics and pharmacodynamics. In the latter case this is due to the de…

Circulatory and metabolic responses of malignant tumors during localized hyperthermia

The effect of localized hyperthermia on the circulatory responses and on the oxygen and glucose supply has been evaluated in tissue-isolated rat tumors utilizing an in situ perfusion system. On the average, localized hyperthermia caused a significant increase in total tumor blood flow after raising of the mean tumor temperature from 37 degrees C to 39.5 degrees C. At higher temperatures (42 degrees C) total tumor blood flow decreased to a level somewhat below the flow during normothermia. However, there were great interindividual differences in the response of blood flow to temperature. The changes in blood flow were paralleled by variations of the O2-consumption and of the glucose uptake o…

Low light level in vitro monitoring of cellular and antigen-antibody reactions using a photon detection camera system — New perspectives for clinical diagnosis and research

This article briefly describes the use of a photon counting system (ARGUS-100) in the detection of low levels of light. The ARGUS-100 was used in determining ATP in cell sections from tumor tissues and in measuring a luminescence-enhanced immunoluminometric assay, using ferritin as the analyte, based on the luminol-peroxide-4-iodophenol reaction with peroxidase as the enzyme. The aim is not so much the presentation of data, but rather to show the potentials of the photon counting camera in increasing our knowledge of the cellular and subcellular levels, as well as lowering the detection limits in already sensitive systems, such as immunoassays.

TISSUE pH-DISTRIBUTION WITHIN MALIGNANT TUMORS AS MEASURED WITH ANTIMONY MICROELECTRODES

Publisher Summary Recent experiments using glass microelectrodes have demonstrated that very low tissue pH-values are prevalent in C3H mouse mammary carcinomas. The acidification of the tumor tissue is the result of an elevated lactic acid production and its inadequate removal. As a consequence of heterogeneities in tumor blood flow and in substrate supply, tissue pH values are distributed heterogeneously within solid tumors. Although glass microelectrodes with tip diameters of about 1 μm and a sensitive length of 10–50 μm have been used, the spatial resolution can be improved utilizing glass coated antimony microelectrodes the sensitive areas of that are restricted to their very tips. This…

Staphylococcal alpha-toxin kills human keratinocytes by permeabilizing the plasma membrane for monovalent ions

Incubation of human keratinocytes with nanomolar concentrations of Staphylococcus aureus alpha-toxin leads to irreversible depletion of cellular ATP. The toxin forms hexamers in the target cell membranes, and rapid transmembrane flux of K+, Na+, and 86Rb+ is observed. Unexpectedly, pores formed in keratinocytes through application of low but lethal doses of alpha-toxin appeared to be considerably smaller than those formed in erythrocyte membranes. They permitted neither rapid influx of Ca2+ or propidium iodide, nor efflux of carboxyfluorescein. Larger pores allowing flux of all three markers did form when the toxin was applied at high concentrations. Flux of monovalent ions and reduction in…

Experimental evidence for a hyperthermia-induced breakdown of tumor blood flow during normoglycemia

A compilation of experimental data is presented indicating that hyperthermia alone can achieve a significant inhibition of tumor blood flow if appropriate heat exposure times and tissue hyperthermia levels are chosen.