[Clinico-pathogenetic significance of enzymes regulating nucleic metabolism in erythrocyte lysates and sera of patients with osteoarthrosis]

Lysates of erythrocytes and sera of 52 patients with osteoarthrosis (OA) and 30 healthy subjects were used used to determine adenosine deaminidase (ADA, AMP deaminase (AMPDA) and adenine deaminidase (AD). Their activities were unrelated to the age and sex of the patients. At admission, patients with OA showed enhanced activity of ADA in sera and reduced activity of AMPDA and AD in lysates compared with normal values. These changes depended on clinical features of OA and were especially pronounced in patients with poly-OA and synovitis. These data suggest participation of enzymes of the adenyl branch of purine metabolism in pathogenesis of OA. Treatment of hospitalized patients allowed to achieve positive dynamics of the above activities coupled to their improved clinical conditions even though enzymatic activity of erythrocyte lysates remained different from that in healthy subjects. It is concluded that enzymatic assays used in the study may be used as additional diagnostic methods for the assessment of synovitis and optimizatic of control over efficiency of OA therapy.

A general method of purification of adenosine deaminase by affinity chromatography

Affinity chromatography has been used to purify adenosine deaminase from various sources: calf spleen, calf intestinal mucosa, chicken duodena and human erythrocytes. For this purpose a specific inhibitor, 9-(p-aminobenzyl) adenine, was synthesized and covalently joined to agarose. Adenosine deaminase is selectively retained by such an inhibitor-resin when highly impure solutions are chromatographed through it. After elution from the resin with guanylurea, a competitive inhibitor, the enzyme is homogeneous and can be recovered in yields of 80 percent or more and the same number of multiple forms of the enzyme is present in the purified preparation and in the crude extract.

Enzyme rate assay for 5-fluorocytosine

Modification of an enzyme assay for 5-fluorocytosine, from an end point to a rate analysis, has resulted in a method that can provide results within 10 minutes. The modification also rendered the assay less susceptible to interference from bilirubin and triglycerides. This obviated the need to correct 5-fluorocytosine results for icteric or moderately lipemic samples. The performance history of the enzyme rate method has shown that it is reliable, quick, cost-effective, and suitable for use in a clinical laboratory.

[Activity of guanase in serum and liver function tests in HBe antigen-positive chronic hepatitis]

Forty-one patients with chronic hepatitis were divided into an HBe antigen-positive group (n = 13) and an HBe antigen-negative group (n = 28) to clarify the relationship between the presence of HBe antigen and liver function. In the HBe antigen-positive group, the activities of serum alanine aminotransferase (p less than 0.01), aspartate aminotransferase (p less than 0.05) and guanase (p less than 0.01) were significantly higher than those in the HBe antigen-negative group. The correlation coefficient between the HBe antigen titer and guanase activity was 0.528, which was higher than the corresponding values for alanine aminotransferase and aspartate aminotransferase. The determination of guanase activity in serum may be useful for evaluating the clinical severity of HBe antigen-positive chronic hepatitis.

Clinical significance of serum guanase activity in various liver diseases

Serum guanase activity was measured using a sensitive colorimetric method in patients with liver diseases. Guanase activity was correlated with GPT, GOT in acute viral hepatitis and chronic hepatitis, however, in liver cirrhosis and hepatocellular carcinoma it was correlated with total bilirubin as well as aminotransferases. In addition, the GPT-to-guanase ratio differed chronic hepatitis from liver cirrhosis. These findings suggest that determination of guanase and aminotransferases in useful in differentiation of liver diseases as well as assessing liver damage.

Simple ultraviolet spectrophotometric method for the determination of serum guanase activity

We describe a simple, kinetic method for the determination of serum guanase activity that involves enzymatic coupling to xanthine oxidase and measurement of the rate of uric acid formation by spectrophotometric monitoring of the absorption at 300 nm. At this wavelength, the absorption of uric acid is about 80% of its maximal absorption at 293 nm, but the difference in molar extinction coefficient between guanine and uric acid is similar (9,000 at 293 nm vs 8,400 at 300 nm). There are three advantages to the use of the higher wavelength: first, the absorption of serum proteins is only one third of the absorption at 293 nm resulting in a significant reduction in noise level. Second, the lower absorption of serum proteins allows increasing sensitivity of the assay by increasing the amount of serum in the reaction mixture. Third, the higher wavelength allows the use of automated centrifugal analyzers that are generally not designed for measurements below 300 nm. The between-day coefficient of variation was 5.8% (n = 27) at an activity of 17 U/L and 8.2% at an activity of 2 U/L. The reference range for 50 sera from males and females was 0.4 to 1.8 U/L (n = 50; mean +/- 2SD). The method is linear to 40 U/L.

Prevention of posttransfusional non-A, non-B hepatitis using the screening test for guanase activity of donor blood

A total of 107 recipients, who did not show any evidence of hepatic disorders in pretransfusional liver function tests and gave a negative reaction for HBsAg, were observed from 3 weeks to 3 months after blood transfusion of 711 units of blood. Of 107 recipients, 18 (17%) developed posttransfusional non-A, non-B hepatitis (PTH). It was detected in 2 of 71 recipients (3%) with blood guanase activities below 3.5 U/L and in 16 of 36 recipients (44%) with blood guanase activities above 3.6 U/L. It is considered that development of PTH could be reduced by avoiding use of donor blood with high guanase activity. We adopted an automated method for measuring guanase in donor blood in the Tokushima Red Cross blood center and examined the incidence of PTH when donor blood with high guanase activity was excluded. Of 112 recipients, 8 (7%) developed PTH. The incidence of PTH was 17% before adoption of the guanase screening test and 7% after its adoption. This work shows that for prevention of PTH it is very important to screen donor blood for guanase activity and discard blood with high guanase activity.

Clinical value of the guanase screening test in donor blood for prevention of posttransfusional non-A, non-B hepatitis

We adopted an automated method for measuring guanase in donor blood and examined the incidence of posttransfusional non-A, non-B hepatitis when donor blood with high guanase activities was excluded. Sixty-seven (2.4%) of 2,826 units were excluded from use in transfusion because they had guanase activities above 1.71 units per liter. Of 112 recipients, 8 (7%) developed posttransfusional non-A, non-B hepatitis. The incidence of posttransfusional non-A, non-B hepatitis was 17% before adoption of the guanase screening test and 7% after its adoption. Thus, the incidence of posttransfusional non-A, non-B hepatitis was significantly decreased after adoption of this screening test. This study shows that, for prevention of posttransfusional non-A, non-B hepatitis, it is important to screen donor blood for guanase activity and discard blood with high activities.

Localization of GTP cyclohydrolase I in human peripheral blood smears using a specific monoclonal antibody and an immune-alkaline phosphatase labeling technique

GTP cyclohydrolase I, the enzyme catalyzing the first step in the cofactor biosynthesis for the aromatic amino acid hydroxylases, has been localized in situ. By the use of a monoclonal antibody specific to human GTP cyclohydrolase I, the enzyme has been visualized immuno-enzymatically by alkaline phosphatase monoclonal anti-alkaline phosphatase labeling. In routine blood smears lymphocytes, monocytes/macrophages, and granulocytes show strong intraplasmatic staining. Premature erythrocytes show clear staining of the reticulated cytoplasmatic structure, while mature erythrocytes are completely negative. Neither is there any staining for GTP cyclohydrolase I in the blast cells of a case of T-cell acute lymphoblastic leukemia. These results closely confirm the prior finding that mature erythrocytes as well as most malignant mononuclear cells lack GTP cyclohydrolase I activity, and they indicate that in these cells the enzyme protein may be absent.

Relationship between guanase activity in donor blood and the incidence of posttransfusional non-A, non-B hepatitis, and a possible method for preventing posttransfusional hepatitis

A total of 107 recipients, who did not show any evidence of hepatic disorders in pretransfusional liver function tests and gave a negative reaction for HBsAg, were observed from 3 weeks to 3 months after blood transfusion of 711 units of blood. The blood was judged suitable for use in transfusion because it had a normal level of ALT activity and gave a negative reaction for HBsAg. The guanase activities of the blood used for transfusion were examined. Cases in which an increase of ALT to at least twice the upper limit of normal persisted for at least 3 weeks and the ALT value increased to more than five times the normal upper limit at least once during this period, which also gave a negative reaction for HBsAg, were judged to have posttransfusional non-A, non-B hepatitis. Of 107 recipients, 18 developed posttransfusional non-A, non-B hepatitis. It was detected in 2 of 71 recipients (3%) with blood guanase activities below 3.5 units per liter and in 16 of 36 recipients (44%) with blood guanase activities above 3.6 units per liter. Thus, the incidence of posttransfusional non-A, non-B hepatitis was significantly higher in recipients with blood guanase activities above 3.6 units per liter. The incidence of posttransfusional non-A, non-B hepatitis increased linearly with increase in the level of guanase activity in donor blood. Thus, a high guanase activity in donor blood is considered to be an important predicting factor for posttransfusional non-A, non-B hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Guanase activity in the donor serum and the incidence of posttransfusion hepatitis non-A, non-B

Guanase activity in sera obtained from various liver diseases and normal subjects was measured by a direct colorimetric method. It was also measured in fresh whole blood (FWB) and fresh frozen plasma (FFP) which were transfused to 78 patients during cardiac operations. Guanase activity was elevated in various liver diseases, and good correlation was found between guanase activity and amino-transferases. Thus, guanase activity was thought to be a good marker of liver damage. Among 78 patients, 17 patients (21.8%) developed posttransfusion hepatitis. All were non-A, non-B hepatitis. Mean value of guanase activity in 1527 units of FWB was 1.96 +/- 1.31 U/L, and in 353 units of FFP it was 2.29 +/- 1.02 U/L. Therefore, the normal upper limit of guanase activity of FWB and FFP was defined as 4.5 U/L (mean +/- 2S.D.). Among 1880 units of FWB and FFP, 56 units (3.0%) exceeded this limit. Among 24 recipients of FWB or FFP with guanase activity above 4.5 U/L, 11 cases (45.7%) developed posttransfusion hepatitis, while in 54 recipients of FWB or FFP below 4.5 U/L, only 6 cases (11.1%) developed hepatitis. This result means that blood or plasma with guanase activity above 4.5 U/L had higher risk of transmitting posttransfusion hepatitis non-A, non-B. Accordingly, a screening of donor blood by the activity of guanase may be useful for the prevention of posttransfusion hepatitis non-A, non-B.

Increase of GTP cyclohydrolase I activity in mononuclear blood cells by stimulation: detection of heterozygotes of GTP cyclohydrolase I deficiency

An assay is described for GTP cyclohydrolase I activity in human mononuclear cells isolated from 20 ml of heparinized blood. The activity of this enzyme was low in unstimulated cells and increased 5-10 times after stimulation by phytohemagglutinin (formation of 0.8-1.3 pmol dihydroneopterin triphosphate/min per mg protein at 37 degrees C, n = 15) or mixed lymphocyte culture. No activity was detected in phytohemagglutinin-stimulated mononuclear cells of a patient with proven GTP cyclohydrolase I deficiency in liver; the samples from the father and mother of the patient showed 30 and 46%, respectively, of the mean of 15 healthy controls. In unstimulated cells, neopterin was the main component of the total intracellular pterins (after oxidation). After stimulation, dihydroneopterin triphosphate, measured as neopterin triphosphate by high performance liquid chromatography, was increased 10-30 times; neopterin and pterin were increased only 2- to 6-fold. Since the immunoreactive cells from this patient were unable to produce pterins and all immunological tests on the patient were normal, it is concluded that neither dihydroneopterin triphosphate, nor one of its metabolites are of primary importance for an immune reaction. The assay described can be used for the detection of heterozygotes of GTP cyclohydrolase I deficiency.

Clinical evaluation of serum guanase activity in liver diseases

We measured serum guanase (EC 3.5.4.3) activity in patients with various diseases and in healthy controls, and evaluated the clinical usefulness of this enzyme in liver diseases. The reference range, which showed no significant difference between sexes and ages over the range studied, was 0 to 1.8 U/L. The mean guanase activities for patients with various liver diseases, including acute hepatitis, chronic hepatitis, liver cirrhosis, hepatoma and metastatic carcinoma, were above the upper limit of the reference range. In acute hepatitis and metastatic carcinoma of the liver, the activities were especially high. Validity (sensitivity + specificity) of guanase, which in all tests was above 1.66, was compared to that of AST and ALT in liver diseases. With guanase, the highest validity (1.98) was found in acute hepatitis and metastatic carcinoma. Specificity of guanase was 0.98, whereas sensitivity of AST was 1.00 in all diseases. Sensitivity and specificity of ALT were 0.85 to 0.97 in all diseases. As guanase was specific, including this enzyme with other liver function tests, such as AST and ALT, may decrease false-positive results and may be effective for prediction of liver disease.

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.