Esteban P. Pineda

The colorimetric determination of γ-glutamyl transpeptidase with a synthetic substrate☆

Abstract A new procedure for the colorimetric assay of γ-glutamyl transpeptidase activity in mammalian tissues using a synthetic chromogenic substrate, N -( dl -γ-glutamyl)-aniline, has been developed. The method is based on the measurement of aniline liberated by the enzymic cleavage of the substrate. The kinetics of the enzymic reaction with rat kidney homogenate are described and evidence is presented that the kidney enzyme which accomplishes the liberation of aniline from this substrate is γ-glutamyl transpeptidase. A study of the distribution of activity in the organs of six mammals indicated that enzymic activity was highest in the kidney in all species.

A Method for the Colorimetric Determination of γ-Glutamyl Transpeptidase in Human Serum; Enzymatic Activity in Health and Disease

Summary A colorimetric method for the assay of γ-glutamyl transpeptidase activity in serum and serous fluids using a synthetic substrate, N-(dl-γ-glutamyl) aniline, is described. The method is based upon the measurement of aniline liberated by the enzymatic cleavage of the substrate. The kinetics of the transfer reaction catalyzed by human serum are described. Serum transpeptidase activity was assayed in 400 normal subjects and 545 patients with cancer and other diseases not involving the hepatobiliary tract or pancreas. The upper limits of normal were 120 units for men and 65 units for women. Most of the patients had normal serum levels and the remainder had elevations that did not exceed 500 units.

A Method for the Colorimetric Determination of β-Glucuronidase in Urine, Serum, Tissue; Assay of Enzymatic Activity in Health and Disease

Summary 1.Methods are presented for the assay of β-glucuronidase activity in urine, serum, tissues. 2.Values are given for serum and urine glucuronidase activity in normal individuals. 3.Serum glucuronidase activity was markedly increased in patients with carcinoma of the head of the pancreas without demonstrable hepatic metastases. Increased urinary activity occurred less frequently. 4.Serum glucuronidase activity was increased in patients with acute pancreatitis and in a significant percentage of those with diabetes mellitus, cardiac decompensation, cancer of the breast. 5.There was no correlation between glucuronidase activity in serum and urine of most patients. 6.Most patients with increased serum glucuronidase activity manifested clinical or laboratory evidence of hepatic dysfunction.

Localization of serum leucine aminopeptidase activity by paper electrophoresis.

Summary The electrophoretic behavior of serum leucine aminopeptidase (LAP) in normal individuals, in pregnancy, and in patients with hepatobiliary disease was investigated with paper electrophoresis technics. In normal serum LAP migrated as a single component in the α1-globulin fraction. In patients with elevated serum LAP activity due to hepatobiliary or pancreatic disease supplementary peaks of enzymatic activity were demonstrable in other protein fractions. Thus, in jaundiced patients with carcinoma of the head of the pancreas, liver metastases, biliary atresia, acute hepatitis, and drug-induced jaundice, additional activity was observed in the β-globulin fraction. In some patients with hepatitis additional activity was observed in the α2-globulin as well as β-globulin. In common duct stone additional activity in the albumin fraction was a consistent finding. In early pregnancy the electrophoretic pattern of LAP was similar to that observed in normal serum, whereas during the third trimester LAP activity was demonstrable only in the α2-globulin. The valuable technical assistance of Mrs. Sally Spurling and Mrs. Thelma Alpren is acknowledged.

A Comparison of Serum Aminopeptidase and Alkaline Phosphatase in the Detection of Hepatobiliary Disease in Anicteric Patients

Excerpt Diseases of the liver, bile duct, or pancreas generally produce an increase in serum aminopeptidase activity (LAP) (1-14). This increase signifies excretory blockade (1, 6). The same is tru...

Leucine aminopeptidase and β-glucuronidase activity in cancerous and noncancerous effusions

SummaryLAP and β-glucuronidase activities were assayed in the serous effusions of 103 patients. The activity of each enzyme was almost always lower in the effusion than in the corresponding serum. In pleural fluid, neither LAP nor β-glucuronidase levels were of value in distinguishing patients with cancer from patients with nonmalignant disease. The meanβ-glucuronidase activity of ascitic fluid was about twice as high in patients with cancer as in patients with cirrhosis or congestive heart failure, but diagnostically useful information could not be obtained from this assay. In contrast, the determination of LAP in ascitic fluid was helpful in distinguishing cancerous from noncancerous ascites. The mean LAP activity of ascitic fluid was 3 times as high in patients with cancer as in those with non-malignant disease. An LAP activity exceeding 95 U. was encountered in 63 per cent of patients with cancerous ascites but in none of those with noncancerous ascites.