The estimation of serum guanosine deaminase activity in liver disease

An assay for the estimation of guanosine deaminase is described. The method employs guanosine as substrate and after incubation of serum and substrate at 22 degrees C for 18 h the ammonia liberated is estimated using the Berthelot reaction. Absorbance is measured as 625 nm and the catalytic activity read from a standard curve obtained using ammonia standards. The method provides reproducible measurements of serum guanosine deaminase. The results obtained using 'normal' sera have been used to calculate the 'normal range' for the enzyme in serum. Preliminary results suggest that guanosine deaminase is increased in hepatitis and in patients with liver metastases but normal in all other liver diseases including cirrhosis and obstructive jaundice.

Guanine deaminase in serum as an indicator of survival probability in severe shock patients

To find ways of predicting survival or death in cases of severe shock, arterial blood pH and gases, vital signs, and the half-life of activity in the enzymes guanine deaminase, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), were studied in 24 patients. The mean arterial blood pH (+/- SD) in survivors was 7.325 +/- 0.092 while that in non-survivors was 7.108 +/- 0.251 (p less than 0.05). The mean half-life of guanine deaminase in survivors was 19.8 +/- 3.3 hours, while that in non-survivors was 58.6 +/- 11.8 hours (p less than 0.001). When the screening values were set at 7.190 for the arterial blood pH and 36 hours for the half-life of guanine deaminase activity, the 'validity' (sensitivity plus specificity) for the combination of the two tests was 1.88. The values may be useful for the prognosis of survival in severe shock patients.

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.

Relationship of serum guanase levels with economic characters in Zebu purebred and temperate x Zebu crossbred dairy cattle

Serum guanase levels of Indian Zebu (Hariana) cattle and its crosses with different exotic levels of temperate breeds of dairy cattle were estimated in 527 animals, and their associations with economic characters were determined. The overall mean value of serum guanase level was 13.46 +/- 0.45 IU/ml of serum. An inverse relationship between the concentration of the enzyme and the frequency of cattle falling within a definite range was observed, as over 75% of the animals possessed 1 to 20 IU/ml of serum guanase. An analysis of variance revealed significant differences (P less than 0.01) in enzyme levels among different genetic groups under study. Hariana (Zebu) purebreds had significantly higher enzyme levels (19.60 +/- 1.85) than any of the crossbred groups, whose enzyme levels ranged from 8.99 +/- 1.41 in Red Dane F1 half-breds to 14.30 +/- 1.11 in Brown Swiss F1 half-breds. The correlation and regression coefficients were significantly positive for reproductive traits such as age at first service and age at first calving, and significantly negative for production traits such as lactation yield and lactation length. These results suggest that selection of dairy cattle based on low serum guanase levels might result in correlated improvements in dairy cattle productivity.

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

A 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 CCl4- 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 CCl4 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.

A sensitive new method for measurement of guanase with 8-azaguanine in bicine bis-hydroxy ethyl glycine buffer as substrate

Serum guanase activity has been considered as a possible specific indicator of hepatocellular diseases. However, no suitable method is available for routine clinical determination of serum guanase activity. Conventional assay methods are troublesome and inaccurate, since guanine and 8-azaguanine, the substrates of the enzyme, are scarcely soluble in water so that it is not possible to prepare a stable substrate solution of sufficient concentration for use in assays. A new method was developed for assay of guanase activity by direct colorimetric determination of ammonia. In this method, bicine bis-hydroxy ethyl glycine (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.

Clinical and experimental studies of the determination of serum guanase activity in acute myocardial infarction

Serum guanase activity was measured by a new method using direct colorimetric determination of ammonia in 25 patients with acute myocardial infarction, 21 dogs with experimental myocardial infarction and 6 CCl4-treated dogs, and compared with serum GOT and GPT activity. We found normal serum guanase activity in patients with acute myocardial infarction and in dogs with experimental myocardial infarction without liver damage, even when the serum GOT and GPT activities increased. On the other hand, serum guanase and transaminase activities were elevated significantly in the patients with acute myocardial infarction who had prominent symptoms of cardiac failure and congestion of the liver and CCl4-treated dogs. These findings suggested that the serum guanase activity was more specific than serum GOT and GPT activity as an indicator of liver damage and determination of serum guanase activity in the patients with acute myocardial infarction might be useful in assessing the presence of liver impairment.

Kinetic measurement of guanine deaminase in serum with a centrifugal analyzer

We describe an enzymic, one-step kinetic method for determination of guanine deaminase (guanase, EC 3.5.4.3) in serum with a centrifugal analyzer. A combined enzyme-substrate system consists of the enzymes xanthine oxidase, catalase, and aldehyde dehydrogenase, the coenzyme NAD+, the substrate guanine, and ethanol in tris(hydroxymethyl)methylamine buffer, with KCl added as activator for aldehyde dehydrogenase. The method requires only 40 microL of sample. Guanase activity in 28 samples can be determined within 10 min by setting a 4-min lag period. The increase in absorbance at 340 nm is linearly proportional to the activity of guanase to 60 U/L. Within-run precision (CV) was 1.32 to 4.50% over the range studied. Day-to-day precision corresponds to CVs of 4.8 to 7.2% over the same range of guanase activity. The reference interval, as calculated from data on 25 healthy humans, was 0 to 1.02 U/L. The enzymic automated method shows good correlation with Caraway's (Clin. Chem. 12: 187, 1966) method (r = 0.949).

A simple and sensitive radiochemical assay for plasma guanase

A simple and sensitive radiochemical micro-assay has been developed for the determination of plasma guanase activity. The method is based upon the measurement of the conversion of 14C-labeled guanine to xanthine, catalysed by the enzyme guanase (guanine aminohydrolase;EC 3.5.4.3). Using this method, the catalytic activity in the plasma of adult healthy controls was 0.040 +/- 0.09 nmol/h.mg protein (x +/- s). In children under 5 years of age higher levels of enzyme activity were demonstrated. In adult patients with liver disease plasma guanase activities were found to be 3 to 7-fold increased as compared to the normal adult mean value.

[Thrombocyte adenase of healthy monkeys and monkeys with different degrees of hemoblastosis]

Sensitive radioactive method was used to study the activity of blood platelet adenase in healthy monkeys and in monkeys with hemoblastosis of different severity. A considerable increase of the specific activity of the enzyme in hemoblastosis with an expressed clinical picture and a reduction of the enzymatic activity at the stage of remission and in mild form of the disease was demonstrated. No adenase was revealed in the platelets of healthy monkeys.

Cytochemical demonstration of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase activity

The enzyme 5-formyl tetrahydrofolate cyclodehydrase plays an important role in the conversion of 5-formyl tetrahydrofolate to 5,10-methenyl tetrahydrofolate. A second enzyme, cyclohydrolase, converts 5,10-methenyl tetrahydrofolate to 10-formyl tetrahydrofolate. These folate derivatives play a significant part in the biosynthesis of purines. A method has been devised for the cytochemical demonstration of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase activity which uses 5-formyl tetrahydrofolate or 5,10-methenyl tetrahydrofolate as substrate respectively, blocking possible interferences by other enzymes, and allows the nonenzymatic reduction of nitro-blue tetrazolium by 5,10-methenyl tetrahydrofolate formed by the action of the cyclodehydrase on the substrate 5-formyl tetrahydrofolate, and by 10-formyl tetrahydrofolate formed by the action of cyclohydrolase on the substrate 5,10-methenyl tetrahydrofolate, thus revealing intracellular sites of enzyme activity. The methods appear to show only intracellular localization of the blue formazan deposits of reduced tetrazolium. The distribution of positivity in cells of human blood and bone marrow is described.

[Adenase of formed elements of blood of donors and of patients with different blood diseases]

The adenase activity was determined in erythrocytes, leucocytes and thrombocytes of donors and of patients with chronic lympholeucosis, chronic myeloleucosis and acute leucosis. A decrease in specific activity of the enzyme was observed in erythrocytes of the patients. In the leucocytes the adenase activity was not found both in normal persons and in all the patients examined. It was shown that the adenase is present in thrombocytes of the patients. Complete absence of the adenase activity was noted in the thrombocytes of healthy donors.

[Studies on the diagnostic value of various enzymatic activties in icterogenic hepatitis of infancy. II. Sorbitol dehydrogenase, guanase and argininosuccinate lyase]

The AA. have determined the levels of argininesuccinatolyase (ASAL), sorbitoldehydrogenase (SDH) and guanase (GUA) in 65 cases of hepatitis of infancy, by comparison with the corresponding levels of transaminases. Of all the enzymes examined, transaminases were the most sensitive sign of liver damage, not only because of their more pronounced rise in the earlier stages of the disease, but also in consideration of their slower regression to normal values. The AA. nevertheless believe that a special significance can be assigned to the determination of SDH for its persistency to levels higher than the normal ones in prolonged hepatitis, and for its quick increase in the recurrences; its regression to normal values may be assumed as an early and clear sign for the demonstration of the stages indicative of recovery.

Serum guanase activities after myocardial infarction

Serum guanase, aspartate aminotransferase, alanine aminotransferase, creatine phosphokinase and hydroxybutyrate dehydrogenase activities were measured in 290 blood samples from 96 consecutive patients admitted to a Coronary Care Unit. Elevated serum guanase activities (greater than 2 U/l) were found in 19 patients (20%). The magnitude and frequency of these elevations did not negate the value of guanase as a "liver function test", since all cases with raised guanase also had abnormal serum alanine aminotransferase activities. This fact, together with other information in the literature, indicated that elevated serum guanase activity following myocardial infarction was consequent upon some degree of sub-clinical hepatic necrosis. Caution must be exercised when serum asparate aminotransferase is used as an index of heart muscle necrosis unless guanase or some other "liver specific" enzyme is known to be normal, or unless creatine phosphokinase or hydroxybutyrate dehydrogenase activities are elevated.

Glutamine aminotransferase and glutamine aminohydrolase ratio as a possible test for antitumour compounds

Three known antitumour drugs have been tested for their effect on the GAT/GNase ratio of Ehrlich Ascites cells and host plasma. It was observed that all these drugs had changed the ratio of the 2 types of glutaminases from below 1.0 to the normal value of 1.0, this was accompanied with an increase in the survival time of the tumour-bearing animals. There was, however, no effect on the plasma GAT/GNase ratio of normal animals in the presence of the 3 antitumour compounds tested.

Red cell esterase D in studies of paternity cases in the United Kingdom

The recently discovered genetic polymorphism of human red cell esterase D has been applied to 156 cases of disputed paternity, along with other well-established systems. The results indicate that esterase D is a useful additional genetic marker for use in paternity testing.