We evaluated colony formation in soft agar by cells obtained after mechanical and/or enzymatic disaggregation of 455 malignant human tumours. Counting and assessment of cell colonies in the agar plates were done by inverted microscopy, computerized image analysis, and inspection of serial photomicrographs of the agar plates. Our results indicate that standard methods of tumour disaggregation did not usually produce single-cell suspensions and that aggregates of tumour cells varying greatly in size were placed in the agar. Most groupings of cells identified as colonies 1-3 weeks after plating arose from enlargement of preexisting aggregates of cells. Images Fig. 1 Fig. 2 Fig. 3

The cytotoxicity of 3 electron-affinic radiosensitizers has been studied in Chinese hamster V-79 cells as a function of pH and modest hyperthermia. When equitoxic concentrations were used and temperature was increased from 34 to 41 degrees C metronidazole, the compound with the lowest electron affinity showed the greatest enhancement of hypoxic-cell toxicity, and nitrofurantoin, the compound with the highest electron affinity, the least. The results can be explained if the mechanisms of toxicity involves a redox reaction, since it would be expected that the least toxic compound (lowest electron affinity) would have the largest activation energy and hence the greatest temperature effect. This appears to hold for these 3 compounds. Experiments also showed that nitrofurantoin which exhibits no increase in toxicity when the temperature was increased from 37 to 41 degrees C at pH 7.4, showed an increase in toxicity for the same temperature change at the pH of 7.0 and 6.6. Under aerobic conditions only metronidazole showed significant toxicity at 41 degrees C, where the differential between aerobic and hypoxic cell toxicity was minimal, both at pH 7.4, and at the low pH values of 7.0 and 6.6. In the clinical setting there is evidence that tumour cells are at a lower pH than their surrounding normal tissues. Hypoxic-cell cytotoxicity is enhanced at low pH, and even further enhanced at low pH in combination with a temperature of 41 degrees C. However, this finding correlates conversely with electron affinity. Thus, the radiosensitizer (and trichomonicide) metronidazole is most influenced by low pH and high temperature with the nitroimidazole, misonidazole, demonstrating a smaller enhancement due to higher temperatures.

Ethylene oxide and 1,2-propylene oxide were each administered intragastrically by gavage at 2 dosages (30 and 7.5 mg/kg body wt; 60 and 15 mg/kg body wt respectively) to groups of 50 female Sprague-Dawley rats twice weekly for a period of nearly 3 years using salad oil as the solvent. Both compounds induced local tumours, mainly squamous-cell carcinomas of the forestomach, dependent on the dosage. The first tumour occurred in the 79th week both in the group treated with ethylene oxide and in that treated with 1,2-propylene oxide. The following tumour rates resulted: ethylene oxide 62 and 16%; 1,2-propylene oxide 40 and 4%. In addition carcinomata in situ, papillomas and reactive changes of the squamous epithelium of the forestomach were observed in other animals, but neither ethylene oxide nor 1,2-propylene oxide induced tumours at sites away from the point of administration. Images Fig. 3 Fig. 4 Fig. 5 Fig. 6

The secretion of CEA into the blood of athymic mice was studied with 4 sublines of human colonic adenocarcinoma cell lines, HT 29 and SLu. Growth curves based on tumour volume (caliper measurements) or tumour mass (weight) correlated with a concomitant increase of serum CEA during the logarithmic growth phase, but showed a marked dissociation when the growth rate slowed down. In the logarithmic growth phase doubling times between 2 and 6 days were calculated and about 6-7 doubling times passed until the shift in the growth rate was observed, independently of the sublines transplanted. Constant increases of CEA between 0.03 and 0.45 microgram/l serum per mm3 increase of tumour volume, depending on the sublines, were recorded during the logarithmic growth phase. Sublines releasing high amounts of CEA in vitro (cell culture) retained this characteristic in vivo. Correlation between tumour volume and tumour mass or serum CEA showed correlation coefficients of 0.820-0.977 during the logarithmic growth phase.

Lung primary carcinomas and normal tissue from 136 patients have been extracted for prostaglandins, and the findings examined in relation to histology. In most cases, tumours yielded more prostaglandin-like material (PG-lm), as judged by bioassay, than did normal tissue from the same lungs. Amounts varied with tumour types, in the following ascending order: small-cell carcinomas, large-cell undifferentiated carcinomas, well-differentiated squamous carcinomas, poorly-differentiated adenocarcinomas, poorly differentiated squamous carcinomas, and well-differentiated adenocarcinomas. Tumour PG-lm was highest when necrosis or the neutrophil content of the tumours were moderate, whereas PG-lm from normal lung tissue correlated with the number of macrophages. Chromatography indicated the presence of various prostaglandins, in agreement with our recent findings using gas chromatography--mass spectrometry.