Takeshi Takaoka

Clinical Value of the Determination of Serum Guanase Activity: Studies on Patients and Experimental Data From Mongrel Dogs and Cultured Rat Hepatocytes

Serum guanase activity was measured by a new method and compared with serum glutamic oxalacetic transaminase and glutamic pyruvic transaminase levels in 150 patients with various disorders, 21 dogs with experimental myocardial infarction, and 2 CCl4-treated dogs. Additionally, studies of the effect of CCl4 on enzyme release were undertaken using cultured rat hepatocytes. Glutamic oxalacetic transaminase, glutamic pyruvic transaminase, and guanase activities were found to be significantly elevated in patients with various liver disorders, those with acute myocardial infarction with prominent congestion of the liver, and also in CCl4-treated dogs. However, serum guanase activity was normal in patients with a variety of non-liver-related diseases including acute myocardial infarction, and in dogs with experimental myocardial infarction without liver damage, even when the serum glutamic oxalacetic transaminase and glutamic pyruvic transaminase activities were increased. The glutamic oxalacetic transaminase, glutamic pyruvic transaminase, and guanase activities in the culture medium of rat hepatocytes indicated in the presence of 0.5 mM CCl4 were elevated. These findings indicate that serum guanase activity is a more specific indicator of liver damage than serum glutamic oxalacetic transaminase and glutamic pyruvic transaminase.

Studies of the clinical application of serum leucine aminopeptidase (LAP) activity determined with leucinamide as substrate

SummaryA new method was presented for the determination of leucine aminopeptidase (LAP). The principle of the method consisted in the measurement of ammonia liberated by the action of LAP with direct colorimetry. Leucine naphthylamide has been widely used as substrate for the determination of LAP (Nap-method), but leucineamide was used (NH3-method) in this study, and the enzyme activities determined by the both methods were compared in various diseases.Serum LAP activity in acute hepatitis was much higher in NH3-method than in Nap-method, but the activity in obstructive jaundice was much higher in the latter than in the former.It was demonstrated that the serum of normal rats and CC14 treated rats contained isozymes (LAP-I and II) which showed the different substrate specificities toward leucinamide and leucine naphthylamide. LAP-I activity was much higher, but LAP-II activity was much lower in the NH3-method than in the Napmethod. LAP-I activity was remarkably elevated by the NH3-method, but not by the Nap-method in the serum of CC14 treated rats.The results suggested that leucinamide was preferable substrate for the measurements of activities of serum LAP in the clinical examinations.

Clinical evaluation of measurement of serum guanase activity as a screening test of liver damage

SummaryA new method was developed for assay of guanase activity by direct colorimetric determination of ammonia. In this method, dotite bicine buffer is used for preparation of a stable substrate solution and with a fixed concentration of substrate of sufficient strength serum guanase can be measured sensitively and reproducibly. This assay system could be used as a routine clinical laboratory test in the diagnosis of liver damage.GOT, GPT and guanase activities were found to be significantly elevated in patients with various liver disorders, and those with acute myocardial infarction with prominent congestion of the liver and also in CCI4-treated dogs. However, serum guanase activity was normal in patients with various other diseases, in those with acute myocardial infarction and in dogs with experimental myocardial infarction without liver damage, even when the serum GOT and GPT activities were increased. The GOT, GPT and guanase in the medium of rat hepato cytes culture with 5.0 mM CC14 were elevated.These findings suggest that serum guanase activity is a more specific indicator of liver damage than serum GOT and GPT. The determination of serum guanase activity in patients without liver damage, even when their serum GOT and GPT levels elevated, might be useful as a screening test of liver damage.