A morphological study of cooling rate response in normal and neoplastic human liver tissue: cryosurgical implications

The process of freezing in normal human livers and in human liver tumors was studied by freezing samples of these tissues with constant cooling rates and then examining the morphology of the frozen tissue, after freeze substitution, with the light microscope. Cooling rates varied from 2 degrees C/min up to approximately 2000 degrees C/min. It was observed that high cooling rates produce extensive intracellular ice in both normal and neoplastic liver. At slow rates of cooling, normal and neoplastic liver cells dehydrated and large extracellular ice crystals formed. Comparison of the frozen normal liver and the frozen malignant tumors shows that for the same rates of freezing, the tumor cells retain more cellular water and therefore show less susceptibility to dehydration at low rates of cooling. At slow cooling rates, the amount of cellular dehydration and consequent vascular and interstitial space engorgement changed with the type of tissue frozen. The greatest amount of dehydration occurred in normal human liver, followed by metastatic colon carcinoma and finally primary hepatocellular carcinoma. These results are important for cryosurgery since they suggest that malignant tissues have a different response to freezing than normal tissues.

Cryomicroscopic analysis of freezing in liver of the freeze-tolerant wood frog

The technique of directional solidification coupled with low-temperature scanning electron microscopy was applied to analyze the freezing of liver slices from the freeze-tolerant frog Rana sylvatica. Micrographs of liver slices from 5 degrees C-acclimated frogs frozen on the directional stage to -7 degrees C showed continuous ice formed along an expanded vasculature with hepatocytes that were shrunken and virtually dehydrated. However, when frogs were given a survivable freezing exposure at -4 degrees C for 24 h, liver slices subsequently frozen in vitro at -7 degrees C were much less shrunken and the presence of intracellular ice crystals (formed when samples were plunged into liquid N2 before microscopy) demonstrated that ample free water remained in these hepatocytes at -7 degrees C. This reduced level of cell dehydration was correlated with the buildup of 280 +/- 61 mumol/g wet wt glucose as a cryoprotectant in liver during the -4 degrees C exposure in vivo. The study provides the first direct cytological analysis of the freezing process in an organ of a freeze-tolerant vertebrate and the first confirmation of the relationship between maintenance of a critical minimum cell volume and freezing survival by these animals.

Effects of cooling rate and glycerol concentration on the structure of the frozen kidney: assessment by cryo-scanning electron microscopy

An experimental technique, employing a directional solidification stage for controlled freezing of tissue samples and low-temperature scanning electron microscopy for observation of the structure of the frozen-hydrated samples, was used to study freezing processes in the kidney. Parametric studies in which the cooling rate during freezing and the concentration of glycerol in the tissue were varied confirmed the results of earlier freeze-substitution studies. The results suggest a mechanism for ice propagation in the kidney similar to that already proposed for the liver, in which ice originates in, and is subsequently propagated through, the peritubular vasculature. The ice front dehydrates the cells and tubular structures encountered in its path, thus preventing intraluminal freezing. At higher rates of cooling and increased concentrations of glycerol there is less dehydration of cortical structure and intraluminal freezing occurs.

[The knowledge of cancer patients about their disease]

160 patients suffering from malignant tumors were interviewed by means of a questionnaire. Most of them had been treated by radiotherapy in a curative intent. The treatment had been finished about one year before, all patients submitted to curative therapy were free from recurrences. 80% out of them knew about their diseases, benignity or malignancy, sites of the primary tumors, and extent of lymph node metastases. Only 5% of the patients had to be informed about their disease at the Radio-oncology Hospital, 88% had been informed already by the physicians before. About 90% of the patients were of the opinion that a complete information was suitable and desired by them. As our patients got older, their desire for information diminished considerably. Even one year after the end of their disease, 34% did not speak frankly with other persons about their disease. The study showed furthermore that the hope of being cured is not affected by information. In this context, 90% of the patients were of the opinion that information should not exceed a certain degree.