Histochemical distribution of guanase in human tissues with guanine in bicine buffer as substrate.

Abstract

Histochemical studies of human guanase have seldom been undertaken, in part because of technical difficulties which result in heavy background staining. We previously reported a modified procedure in which the methodological inadequacies had been overcome. In this report, the modified technique has been applied to determine the distribution of guanase in normal human tissues and in cases of chronic hepatitis, hepatocellular carcinoma and metastatic tumors in liver (adenocarcinoma of colon). Guanase was present within the cytoplasm of hepatocytes throughout the entire lobule. Portal components (bile ducts and veins), fibrous tissue and inflammatory cells were non-reactive, and the enzyme was absent from hepatocyte nuclei in the normal liver. However, in the case of non A non B hepatitis nuclei presenting guanase activity or otherwise were identified. Guanase activity was observed for primary liver tumor but not for metastatic tumor. Moreover, guanase activity was observed in proximal tubuli of kidney and mucosal epithelium of small intestine. No activity was found in other tissues. The present method can be regarded as a useful method, not only to examine the specificity of guanase for hepatic diseases, but also to elucidate the physiological significance of guanase in the kidney and small intestine.