Measurement of serum lipase activity with the oxygen electrode

We describe the measurement of lipase (triacylglycerol lipase; EC 3.1.1.3) in serum by continuous monitoring of relative rates of oxygen consumption with a polarographic oxygen electrode. The reactions described by Proelss and Wright (Clin. Chem. 23: 522-531, 1977) are used: trilinolein, with lipase catalysis, yields linoleic acid, which reacts with oxygen in the presence of lipoxygenase. Lipase activity is measured by comparing the zero order reaction rate of the specimen with that obtained with linoleic acid standards. Results for lipase (y) correlated well with those by the copper-soap method of Myrtle and Zell (x) (Clin. Chem. 21: 1469-1473, 1975); y = 0.33x - 11; r = 0.98; n = 34. Results are unaffected by specimen dilution, and the standard curve is linear to 520 U/L. Day-to-day precision (CV) is 10.4% for normal activities, 6.1% for above-normal activities. We believe the method offers a precise, practical approach to lipase analysis.

Biochemical and clinical studies on human pancreatic deoxyribonuclease I inhibitor

Human pancreatic Deoxyribonuclease I (DNase I), inhibitor was partially purified from duodenal juice of healthy subjects collected in the Pancreozymin-Secretin test, by a procedure which included ammonium sulfate fractionation, DEAE cellulose fractionation, Sepharose 4B affinity chromatography, and gel filtration. The final preparation inhibited DNase I only, and had no inhibitory activity on pancreatic RNase, and trypsin. The inhibitor had a molecular weight of approximately 40,000, as determined by gel filtration, and showed the same mobility as skeletal muscle actin on SDS gel electrophoresis. Then clinical studies were made on the DNase I inhibitor in duodenal juice obtained after administration of Pancreozymin and Secretin to patients with various pancreatic diseases. In patients with suspected chronic pancreatitis with whom the ordinary test, containing the assay of the total volume, amylase output and maximum bicarbonate concentration of duodenal juice had produced normal results, the DNase I inhibitor output was observed to be higher than that in control subjects. While it was lower in patients with confirmed chronic pancreatitis than in control subjects. There results imply that DNase I inhibitor output may be an indicator of the pancreatic inflammation state and be useful for the early detection of pancreatic diseases.

The diagnosis of exocrine pancreatic disease: the present position reviewed

In this paper, recent advances in the diagnosis of pancreatic disease are reviewed, together with older methods currently in use. The clinical role of these techniques in the diagnosis of pancreatic disease is discussed with particular reference to symptomatology and prognosis of the various pancreatic disorders. Likely future developments in this field are considered.

Pancreatic juice gamma-glutamyltransferase, alanine transaminase, and alkaline phosphatase in pancreatic disease

Pancreatic juice gamma-glutamyltransferase (GGT, EC 2.3.2.2) has been proposed as a marker of pancreatic disease. We have collected pancreatic juice endoscopically from 24 control patients and 43 patients with a variety of hepatic, pancreatic, and biliary disorders. Pancreatic juice GGT, alanine transaminase (ALT, EC 2.6.1.2), and alkaline phosphatase (ALP, EC 3.1.3.1) were measured and found to be present in all samples. GGT was significantly higher in patients with pancreatic cancer (range 21-1175 IU/liter, P less than 0.005) compared with controls (range 2-52 IU/liter). Of 17 patients with pancreatic juice GGT concentrations greater than 52 IU/liter, eleven had definite pancreatic disease (seven pancreatic cancer, four chronic pancreatitis) and, in the remaining six, pancreatitis was possible although not proven. Pancreatic juice ALT and ALP provided no useful diagnostic criteria. GGT in pancreatic juice seems to be a nonspecific marker of pancreatic disease and merits further study.

[Amylase excretion in the feces]

The amylolytic excretion in stool was determined in 100 patients with various gastroenterologic diseases and in 55 healthy subjects. The amylolytic activities were detected in disc electrophoresis. The fecal amylase elimination correlates with the weight of stool and is augmented in pancreatopathies, and in other gastroenterologic diseases. The measurement of amylase activity in stool is not suitable for the diagnosis of exocrine pancreatic dysfunction.

Fatty acid composition of erythrocyte phospholipids from patients with cystic fibrosis

The phospholipid fatty acid composition of erythrocytes from patients with cystic fibrosis with pancreatic insufficiency, patients with cystic fibrosis with normal pancreatic enzyme function, and normal subjects was determined. Increased percentages of palmitoleic acid and total eicosatrienoic acid and a decreased percentage of linoleic acid were observed only in the cystic fibrosis patients with pancreatic insufficiency.

Acute hemorrhagic pancreatic necrosis in mice: the activity of lysosomal enzymes in the pancreas and the liver

The activity of lysosomal enzymes of the pancreas and the liver has been studied during induction and onset of acute hemorrhagic pancreatic necrosis with fat necrosis (AHPN) in mice. We induced AHPN by feeding the animals a choline-deficient (CD) diet containing 0.5% DL-ethionine (CDE). Control animals were fed either laboratory chow or a plain CD DIET. Increased total activities of cathespin B1, beta-galactosidase, and acid phosphatase were found to occur in pancreas homogenates of mice fed the CDE diet for 2 and 3 days. Release of cathespin B1 into pancreas cytosol was observed after 1 day of feeding. beta-galactosidase and acid phosphatase were increased in pancreas cytosol after 2 and 3 days of feeding. Changes in total activity and location of the lysosomal enzymes did not occur in the liver. Feeding the CD and CDE diets resulted in an increase in the free activity of lysosomal enzymes of both the pancreas and the liver, suggesting the existence of alterations in the lysosomal membrane. Pancreas and liver homogenates were stored on ice up to 3 hours, and the free activity of acid phosphatase and beta-galactosidase were determined at various time intervals. The free activity of both enzymes increased progressively for 3 hours in the pancreas but not in the liver. It is concluded that: 1) induction of AHPN in mice is accompanied by an increase in the activity of lysosomal enzymes of the acinar cells of the pancreas; 2) cathepsin B1 may be responsible for triggering an intraparenchymal activation of zymogens, and 3) pancreatic lysosomes are labilized more easily than liver lysosomes.

Enzyme measurements in the investigation of pancreatic diseases

Because of the location of the pancreas deep in the abdominal cavity, laboratory tests play a major role in the diagnosis of pancreatic diseases. Amylase and lipase determinations in serum are most frequently performed and they complement each other. However, false positive and false negative results are observed. In order to increase the sensitivity and specificity of diagnostic tests, urine amylase determinations, measurements of the CAmyl Ccreat ratio and amylase isoenzyme determinations are performed. The benefits of these procedures and their limitations will be discussed. The increased sensitivity and specificity of immunoreactive trypsin determinations and contributions of this test to the early diagnosis of pancreatic disease will be described. This test seems to have some usefulness in the early diagnosis of cancer, together with the secretin and pancreozymine-cholecystokinin test and the test for ribonuclease activity in serum.

Intestinal concentrations of pancreatic enzymes following pancreatic replacement therapy

The activities of amylase, lipase, phospholipase, and trypsin in four commercially available preparations of pancreatin with different galenic and adjunctive protective properties were estimated in vitro, using human small-intestinal juice as the incubation medium. These preparations were administered to healthy subjects and to patients with severe pancreatic insufficiency, and their ability to increase the intestinal concentrations of pancreatic enzymes was evaluated. The relations between in vitro and in vivo activities were also studied. In vitro testing showed that the preparations contained high but varying activities of enzymes, with the greatest variations in lipase and trypsin. Pancreatin in the form of tablets, with or without protective measures against acid, did not cause any apparent increase in the activities of pancreatic enzymes in the upper part of the gut in patients with pancreatic insufficiency. Granulated pancreatin, on the other hand, brought about an increase in the activities of amylase, phospholipase, lipase, and trypsin. Relatively higher activities of the enzymes in granulated form reached the small intestine as compared with those of the tablets.

alpha-Amylase of human pure pancreatic juice: effects of pancreatic disease and the occurrence of variant forms in pancreatic juice from healthy volunteers

Pure pancreatic juice (PPJ) from healthy human volunteers and from patients with pancreatic or liver disease was subjected to isoelectric focussing (IEF) and assayed for alpha-amylase activity. In PPJ from most normals, a single predominant form of amylase was found, comprising congruent to 83% of the total activity recovered, and having pIapp congruent to pH 6.8. In PPJ from six normals, variant principal forms of amylase were found at pH congruent to 6.4 or pH congruent to 7.3, in addition to the peak at pH 6.8. IEF patterns of PPJ from individuals with pancreatic or liver disease were indisquishable from patterns obtained with PPJ from the control group of healthy volunteers.

[Lipase and carboxypeptidase A in human serum: no correlation (author's transl)]

The catalytic concentrations of lipase and carboxypeptidase A in sera of patients with and without pancreatic diseases show no correlation. 40 sera out of 44 with elevated values for lipase, derived from a collective of 135 different sera, showed no increase in the catalytic concentrations of carboxypeptidase A. The demanding titrimetric determination of lipase cannot be replaced by the more simple colorimetric determination of carboxypeptidase A for the laboratory diagnosis of pancreatic diseases.

Immunoreactive serum trypsin in diseases of the pancreas

Immunoreactive serum trypsin was measured with a double antibody radioimmunoassay in normal subjects and patients with various diseases of the pancreas. The normal range is 115-350 ng/ml with a geometric mean of 212 ng/ml. No trypsin was found in serum after total duodenopancreatectomy, in about 75% of patients with cystic fibrosis and in a few patients with pancreas carcinoma or chronic pancreatitis. Reduced serum trypsin levels between 10 and 100 ng/ml were measured in the remaining 25% of cystic fibrosis and in one third of the patients with chronic pancreatitis. Serum trypsin was increased to 700-17,000 ng/ml in all patients with acute pancreatitis or during the acute phase of chronic pancreatitis. Absent or reduced serum trypsin is a reliable indicator of total or partial exocrine pancreatic insufficiency whereas considerably increased serum trypsin concentration do indicate acute pancreatitis.

Serum immunoreactive trypsin concentration after a Lundh meal. Its value in the diagnosis of pancreatic disease

The changes in serum trypsin concentration have been measured in 47 subjects for up to 2 hours after a Lundh meal. In 18 healthy controls, mean fasting trypsin concentration was 285 +/- 125 ng/ml (mean +/- 2 SD). The maximum increase after the Lundh meal (the trypsin response ratio) was 6.7 +/- 7.5%. Six patients with chronic renal failure had elevated fasting serum trypsin concentrations (range 460-1100 ng/ml) but trypsin response ratios fell within the control range. Of five patients with relapsing pancreatitis, two had raised and three normal or low fasting trypsins. After stimulation two had elevated trypsin response ratios; one of the two had evidence of main duct obstruction. Eleven out of 12 patients with chronic pancreatitis (with or without insufficiency) had low fasting trypsin concentrations (range 0-120 ng/ml) Seven of the 12 also had raised trypsin response ratios. In six patients with cancer of the pancreas, fasting trypsin was low in three, normal in two, and raised in one. Both patients with a normal fasting level had a raised trypsin response ratio. The combination of a single estimation of fasting serum trypsin concentration followed by serial measurements after a Lundh meal provides a useful screening test for chronic pancreatic disease.

Biochemical changes in the jejunal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency

The roles of extracellular and intracellular mechanisms in the degradation of brush border proteins have been investigated by studying the small intestinal mucosa of dogs with naturally occurring exocrine pancreatic insufficiency. Peroral jejunal biopsies were homogenised and the organelles separated by isopycnic centrifugation on continuous sucrose density gradients. The distributions of marker enzymes for the principal subcellular organelles were determined in the gradients and related to the specific activities in the homogenates. There were increased activities of the brush border carbohydrases zinc-resistant alpha-glucosidase, maltase and sucrase in the pancreatic insufficient animals, but no change in lactase activity. The activity of gamma-glutamyl transferase was also higher in the affected group; the activities of two other brush border enzymes, alkaline phosphatase and leucyl-beta-naphthylamidase, however, were unaltered. These findings with an increase in the modal density of the brush border from 1.20 to 1.22 are consistent with an enhanced glycoprotein content of the microvillus membrane. There were also rises in the activities of lysosomal enzymes. N-Acetyl-beta-glucosaminidase activity was increased in the soluble fractions and the percentage latent enzyme activity was reduced, findings indicative of an increased fragility of the lysosomal membrane. There were no marked alterations in the activities or density gradient distributions of marker enzymes for the other organelles, stressing the specificity of the changes in the brush borders and lysosomes. These findings are compatible with the degradation of certain exposed brush border proteins by pancreatic proteases and suggest that when this is defective, intracellular degradative mechanisms may be stimulated.

Medical treatment of pancreatic insufficiency

Treatment of exocrine pancreatic insufficiency with the use of eight tablets of pancreatin with meals consisting of 25 g of fat per meal will generally abolish azotorrhea. Although steatorrhea is not totally corrected, satisfactory nutritional status and relative relief of symptoms are usually achieved. For the occasional patient who continues to lose weight or remains symptomatic even after reduction of dietary fat, the addition of cimetidine to the standard pancreatin treatment will usually provide relief from the steatorrhea and alleviate troublesome diarrhea. In certain circumstances in which gastric pH is more than 4 for 1 hour after a meal, altering the dosage schedule to two tablets hourly may be effective in alleviating the steatorrhea. Conversely, in patients whose upper gastrointestinal tract is acidic for long periods postprandially (gastric pH less than 5, duodenal pH less than 4), Pancrease, an enteric-coated preparation, may be effective. In difficult cases in which symptoms and steatorrhea continue, special intraluminal studies need to be performed to ensure that intraluminal conditions are, in fact, present for certain dosage schedules to be effective or that intraluminal conditions have been altered by adjunctive therapy.