J. Edward Berk

Value of pancreatic-type isoamylase assay as an index of pancreatic insufficiency.

The study here reported was undertaken to assess the value of assay of the specific isomylase form arising from the pancreas (P-type) as an index of pancreatic exocrine insufficiency. Measurements were made of serum total amylase activity, serum P-type isoamylase activity, and the amount of P-type isoamylase relative to creatinie (Upam/Ucr) in the urine in a series of patients with clinically suspected chronic pancreatitis and pancreatic insufficiency as determined from the pancreatic secretory response to secretin stimulation. Abnormally low values for P-type isoamylase in the serum and urine of these patients were infrequent. Conversely, values within the normal ranges for serum P-type isoamylase and Upam/Ucr were common. It is concluded that while subnormal values for P-type isoamylase in the serum and urine may be viewed as supportive evidence for pancreatic insufficiency, failure to find such values does not exclude this condition.

Nonpancreatic-type hyperamylasemia associated with pancreatic cancer

SummaryIsoamylase anaysis of the serum and urine of a patient with anaplastic spindle cell carcinoma of the pancreas revealed that virtually all of the serum amylase and almost all of the urine amylase behaved chromatographically as the salivary (S) type. Both the serum and urine amylases were bound by a substance derived from a macroamylase complex which had been shown to bind only salivary amylase and to lack any affinity for pancreatitis (P) type amylase. The ratio of amylase to creatinine clearance was markedly increased (12.5%) without evidence of acute pancreatitis at autopsy and despite the presence of only a minute amount of P-type isoamylase in the serum.

Unusual isoamylase in cancer‐associated hyperamylasemia

Hyperamylasemia and hyperamylasuria were found in two patients with carcinoma of the pancreas and in two other patients with carcinoma of the lung. Detailed isoamylase analyses were conducted on the serum amylase of three and the urine amylase of all four of these patients, using a modified chromatographic procedure. The studies demonstrated the existence, in one of the lung cancer patients and in one of the patients with pancreatic cancer, of an unusual component of amylase given the designation “Y.” This component had also been noted in some human milk samples. In one of the lung cancer patients, an isoamylase was found in the serum and urine after radiation treatment that was close to but not identical to the Y isoamylase in chromatographic position. Although a relationship of isoamylase component Y to generating tissue is suggested by these findings, such a relationship remains to be proven.

Serum amylase changes during pregnancy

Study of the behavior of serum amylase activity in 200 preganant women in various stages of pregnancy indicated that: (1) serum amylase rises gradually during pregnancy until the twenty-fifth week and thereafter falls slightly; (2) serum amylase values may be found in normal pregnant women during the second and third trimesters that exceed those in normal men and nonpregnant women; (3) during the second trimester of pregnancy there may be an alteration in the relative distribution of the pancreatic and salivary-type isoamylases with the salivary type tending to dominate. Knowledge of these changes is of importance in the clinical assessment of serum amylase values in pregnant women complaining of abdominal pain and other symptoms suggestive of complicating acute pancreatitis. An explanation for the observed changes is not readily available and further study is required.

Ultracentrifugal characteristics of macroamylasemic serum

Abstract Sedimentation coefficients of the amylases present in the sera of 22 patients with macroamylasemia were measured by means of sucrose density gradient ultracentrifugation using beef liver catalase (11.3 S) and the 7 S serum proteins as markers. The sedimentation coefficients of the macroamylases in 18 of the cases ranged from 7.7 S to 10.7 S; in four cases the activity peaks were too broad to assign a definite sedimentation coefficient. One exceptional case (Case 6) exhibited two peaks of amylase activity: one had a sedimentation coefficient greater than the 19 S serum proteins and the other a coefficient of 10.7 S. The normal-size amylase component seen on dextran gel filtration was no longer discernible after ultracentrifugation in eight of the cases. These observations, in contrast to those on the paper electrophoretic pattern of those sera, suggest that the macroamylase complexes in patients with macroamylasemia are not homogeneous. The observations also indicate that dextran gel filtration may lead to erroneous concepts regarding the component fractions of serum amylase and their molecular sizes because of interaction between amylase and dextran.

Simplified chromatographic method for isoamylase analysis

A simplified and relatively rapidly performed chromatographic method for measuring the principal isoamylases in serum and urine has been developed. It is hoped that this method may help make isoamylase analysis more readily applicable in the ordinary clinical setting.

Observations on a new simplified dye method for assessing amylase activity.

A method utilizing a newly synthesized dye-labeled amylose substrate (Cibachron Blue F3GA-Amylose) provides a simple and reliable means for assaying serum amylase activity. The results correlated well with those obtained with an established saccharogenic method, especially at lower levels of amylase activity. More reliable results at higher levels of amylase activity may be obtained by modifying the procedure so as to employ 200 mg of the substrate. The chromogenic substrate is additionally of potential value as another means of differentiating amylases of different origins.

Serum isoamylase changes following endoscopy

Hyperamylasemia occurred in 24 (66.7%) of 36 patients in whom endoscopic retrograde cholangiopancreatography (ERCP) was performed. The rise was predominantly of pancreatic (P-type) isoamylase in 20 (83.3%) of the 24 with hyperamylasemia and of salivary (S-type) in the remaining 4 (16.7%). In patients in whom the pancreatic duct was visualized, alone or together with the common bile duct, 81.8% displayed hyperamylasemia. Isoamylase analysis revealed that the rise in this particular group was predominantly in P-type isoamylase. By contrast, only 1 of 23 patients with normal pre-examination Amylase values who underwent esophogogastroduodenoscopy without attempted cannutation of either the bile or pancreatic ducts; displayed hyper-amylasemia. It is concluded that hyperamylasemia developing after ERCP in which the pancreatic duct had been opacified probably reflects induced pancreatic alteration.

Macroamylasemia: Variation in the Response of the Macroamylase Complex to Acidification

Summary Acidification had a variable effect on the integrity of the large amylase component in the sera of 21 patients with macro-amylasemia. Reduction of pH to 3.4 resulted in complete dissociation of the macroamylase in 13 cases; partial dissociation occurred in six while two remained unchanged. The response to acidification could be correlated with the sedimentation coefficients of the complexes: macroamylases with the highest coefficients tended not to be affected by acidification; those with the lowest values tended to be completely dissociated, while those with intermediate values tended to be partially dissociated. The variable response to lowering of the pH provides further evidence pointing to heterogeneity of the macroamylase complexes.

Electrophoretic characteristics of macroamylasemic serum

Abstract Serum samples from 28 patients with macroamylasemia were studied by paper electrophoresis. Amylase activity appeared as a single peak located between the γand β-globulin zones and did not differ appreciably from normal serum amylase in electrophoretic mobility. When segments of the electrophoretic paper strip showing amylase activity were eluted and the eluate examined by dextran gel chromatography, the single peak was found to contain both a macroamylase component and the amylase of normal molecular weight. The ratio of macroamylase to amylase of normal molecular weight differed to a variable degree, however, from that in the untreated whole serum. Although the mechanism responsible for this change in ratio is not clear, it is possible that the macroamylase complex was partially dissociated by the electric field.