Assay of pancreatic amylase with use of monoclonal antibodies evaluated

To evaluate a new method for measuring pancreatic amylase in serum, in which the salivary isoenzyme is inhibited with a specific monoclonal antibody, we determined the activity of pancreatic and salivary amylase in sera from 103 healthy subjects and from 114 hospitalized patients having a wide range of total amylase activities. CVs for the proposed method ranged from 0.8% to 5.1% (within day) and from 2.3% to 6.6% (day to day). Results correlated well with those obtained by the wheat-germ inhibition method (r = 0.998) and by electrophoresis on cellulose acetate. Analytical-recovery studies confirmed the good specificity of the monoclonal antibody for salivary amylase (97%) and its low cross-reactivity (0.6%) toward pancreatic amylase. The assay procedure presents a wide range of linearity (141-1817 U/L) and can easily be adapted to an automated kinetic system. We found the proposed method suitable for routine determinations of pancreatic amylase.

Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.

Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.

Serum carcinoembryonic antigen in the differential diagnosis of pancreatic cancer: influence of tumour spread, liver impairment, and age

In order to verify the role of CEA in the differential diagnosis of pancreatic cancer and to evaluate some influencing factors like age, tumor spread and liver dysfunction, this antigen was measured in the sera of 60 control subjects, 45 patients with pancreatic cancer, 37 with chronic pancreatitis, 67 with benign, and 28 with malignant extra-pancreatic diseases. CEA was found to be elevated in 23/45 pancreatic cancers, in 8/37 chronic pancreatitis, in 17/67 benign and in 9/28 malignant extra-pancreatic diseases. Significant correlations were documented between CEA and age in all the subjects; between CEA and immunoglobulins G in liver cirrhosis and between CEA and alkaline phosphatase in gastrointestinal extra-pancreatic malignancies. In pancreatic cancer higher CEA levels were detected in patients with metastases. We can conclude that CEA is of limited value in the differential diagnosis of pancreatic cancer; it does not seem to be able to detect early pancreatic tumors. Age and liver dysfunction may contribute towards elevating this marker in serum.

Serum markers and clinical data in diagnosing pancreatic cancer: a contrastive approach

In order to assess the value of serum markers and simple clinical data in the differential diagnosis of pancreatic cancer, we studied 32 control subjects and 28 patients with pancreatic cancer, 26 with chronic pancreatitis, and 37 with extra-pancreatic diseases. CA 19-9 was found to be the best marker in detecting pancreatic cancer. Among the clinical data, presence and onset of pain attacks, age, and weight loss were selected as the most informative in assessing chronic pancreatic disease. Clinical data correctly classified 88.5% of chronic pancreatitis and 75.0% of pancreatic cancer; serum markers identified pancreatic tumor in 67.9% of the patients. The adjunct of serum markers to clinical data did not improve accuracy in diagnosing chronic pancreatic disease. Since clinical data and serum markers generally become positive at an advanced stage of the disease, early diagnosis of pancreatic cancer is a goal still to be attained.

Influence of isoenzyme patterns on commutability in enzyme determinations

The use of recommended methods has very much improved the precision and accuracy of enzymatic determinations. The use of 'enzyme reference materials' allows us to overcome the remaining difficulties. The possibility of extending standardization by using calibration materials to convert results obtained by different methods requires an essential property: 'commutability'. The relationship between patients' specimens and reference materials are conditioned by analytical causes (relative to the used methods) and clinical causes (relative to the condition of the human samples to be examined). Among the clinical causes, the different isoenzyme content of patients sera, induced by different pathologies, was considered. The effect of this influence has been investigated with an analytical approach of the isoenzymes in the individual clinical samples. The results obtained on determination of alkaline phosphatase (ALP), creatine kinase (CK), and lactate dehydrogenase (LD), are discussed according to a model of investigation which can be utilized for the experimental protocols in the assessment of commutability.

Combined determination of serum CA 19-9 and tissue polypeptide antigen: why no improvement in pancreatic cancer diagnosis?

CA 19-9 and tissue polypeptide antigen (TPA) were determined in the sera of 28 control subjects, 29 patients with pancreatic cancer, 26 with chronic pancreatitis and 62 with benign and malignant extra pancreatic diseases in order to compare their usefulness in diagnosing pancreatic cancer, to verify whether the combined assessment of the two indices could improve the results given by a single parameter and to speculate on the role of liver dysfunction in increasing their serum levels. The sensitivity, specificity and accuracy of CA 19-9 and TPA in diagnosing pancreatic malignancy were: 76, 85 and 61% for CA 19-9 and 79, 52 and 32% for TPA. The receiver-operating characteristic curves showed that CA 19-9 and TPA similarly discriminate pancreatic cancer from controls and chronic pancreatitis, while CA 19-9 is more useful than TPA in differentiating pancreatic malignancy from benign and malignant extra pancreatic abdominal diseases. TPA did not seem to add further information as compared to CA 19-9 alone when both markers were combined. Liver dysfunction may contribute to increasing serum levels of both markers.

Bronchoalveolar neutrophilia during late asthmatic reactions induced by toluene diisocyanate

The mechanism by which late asthmatic reactions are induced by toluene diisocyanate (TDI), a low molecular weight chemical that causes occupational asthma in exposed subjects, is unknown. We investigated whether early and late asthmatic reactions induced by TDI are associated with changes in airway responsiveness to methacholine and airway inflammation as determined by bronchoalveolar lavage. We measured FEV1 before and at regular intervals after exposure to TDI, and performed dose-response curves to methacholine and bronchoalveolar lavage at 8 h after TDI in a group of 6 subjects with late asthmatic reactions and in 6 subjects with only early asthmatic reactions. The same procedure was followed 2 h after TDI in a group of 6 subjects with previously documented late asthmatic reactions and in a group of 6 subjects without any previously documented asthmatic reaction after TDI. In subjects with late asthmatic reactions, neutrophils were increased at both 2 and 8 h, and eosinophils and airway responsiveness were increased only at 8 h. By contrast, neutrophils, eosinophils and airway responsiveness were not increased at 8 h after TDI in subjects with an early asthmatic reaction or at 2 h after TDI in normal control subjects. These results suggest that late asthmatic reactions to TDI, and the associated increase in airway responsiveness, may be caused by airway inflammation.

Immunoglobulin A (lambda chains) conjugated with lactate dehydrogenase in serum

An atypical pattern for lactate dehydrogenase (EC 1.1.1.27) isoenzymes in a patient with sclerosis of the bladder neck was ascribable to complexing between lactate dehydrogenase and IgA. This complex formation was also replicable "in vitro." We determined that the IgA bound to lactate dehydrogenase was of the lambda type, a very unusual occurrence.

Immunoglobulin A (lambda chains) conjugated with lactate dehydrogenase in serum

An atypical pattern for lactate dehydrogenase (EC 1.1.1.27) isoenzymes in a patient with sclerosis of the bladder neck was ascribable to complexing between lactate dehydrogenase and IgA. This complex formation was also replicable "in vitro." We determined that the IgA bound to lactate dehydrogenase was of the lambda type, a very unusual occurrence.

CA 19-9 and carcinoembryonic antigen in pancreatic cancer diagnosis

CA 19-9 (Centocor, Malvern, PA) and carcinoembryonic antigen (CEA), two recently developed immunoradiometric assays utilizing monoclonal antibodies, were evaluated in the sera of 139 subjects in order to assay their individual and combined value in pancreatic cancer diagnosis and to assess the influence of jaundice. Sensitivity, specificity, and accuracy in detecting pancreatic cancer were 69%, 85%, and 54% for CA 19-9; and 28%, 78%, and 6% for CEA, respectively. Combined evaluation gave the highest specificity (95%) when both, and the highest sensitivity (79%) when at least one, gave pathologic results. The receiver-operating characteristic curves demonstrated that CA 19-9 is more discriminating than CEA, for any serum value. A correlation between serum bilirubin and CA 19-9 was demonstrated in pancreatic and extrapancreatic disease. CEA determination, performed using monoclonal antibodies, seems to be unsatisfactory as compared to CA 19-9 in pancreatic cancer diagnosis, and combined assessment does not improve the results of CA 19-9 alone. Jaundice may influence serum CA 19-9 in pancreatic and extrapancreatic diseases.

[The role of CEA, CA 19-9 and TPA in the diagnosis of pancreatic cancer. Evaluation by discriminant analysis]

In order to assess the relative value of CA 19-9, Tissue Polypeptide Antigen (TPA) and Carcinoembryonic Antigen (CEA), evaluated alone and in combination, in diagnosing pancreatic malignancy, serum CA 19-9, TPA and CEA were determined in 25 control subjects (CS), 26 pancreatic cancer (PC), 23 chronic pancreatitis (CP) and 21 benign extra-pancreatic diseases (EPD). The three markers were able to allocate the subjects correctly in 56.8% of the cases (CS 100%, PC 73.1%, CP 17.4%, EPD 28.6%). Sensitivity, specificity and diagnostic accuracy in detecting pancreatic cancer were respectively: 77%, 91% and 68% for CA 19-9; 92%, 75% and 67% for TPA; 50%, 84% and 34% for CEA; 73%, 91% and 64% for the three parameters evaluated simultaneously. CA 19-9 and TPA appear to be useful indices of pancreatic cancer with a satisfactory specificity when related to chronic pancreatitis; their diagnostic value seems to be comparable and better than that of CEA; the combination of these markers does not improve the results obtained by CA 19-9 or TPA alone.

New method ("SPAC ET") for free thyroxin in serum evaluated

We analytically and clinically evaluated a new commercial method ("SPAC ET") for simultaneously determining total and free thyroxin in serum. We found the method to be rapid, simple, and precise. Results significantly correlated with those by "symmetric" dialysis and also agreed with the clinical data for patients with extremely low or high concentrations of thyroxin-binding globulin. On contrast, in those patients the most commonly used thyroid indexes (free thyroxin index or thyroxin:thyroxin-binding globulin ratio) failed to correctly reflect the true functional status of the thyroid.

New method ("SPAC ET") for free thyroxin in serum evaluated

We analytically and clinically evaluated a new commercial method ("SPAC ET") for simultaneously determining total and free thyroxin in serum. We found the method to be rapid, simple, and precise. Results significantly correlated with those by "symmetric" dialysis and also agreed with the clinical data for patients with extremely low or high concentrations of thyroxin-binding globulin. On contrast, in those patients the most commonly used thyroid indexes (free thyroxin index or thyroxin:thyroxin-binding globulin ratio) failed to correctly reflect the true functional status of the thyroid.

Serum elastase 1 and immunoreactive trypsin in chronic pancreatic disease: is there any relationship with trypsin inhibitors?

In order to investigate modifications of serum levels of elastase 1, immunoreactive trypsin, alpha 1-antitrypsin and alpha 2-macroglobulin in chronic pancreatic disease, and to speculate on the possible relationships among these parameters, the enzymes and inhibitors were assayed in the sera of 33 control subjects, 34 pancreatic cancer, 28 chronic pancreatitis and 36 extra-pancreatic diseases. An increase of elastase 1, alpha 1-antitrypsin and alpha 2-macroglobulin was detected in pancreatic cancer, chronic pancreatitis and extra-pancreatic diseases; no changes were found for serum immunoreactive trypsin. Multiple regression analyses showed that only 7% of elastase 1 was explained by inhibitors with alpha 1-antitrypsin playing a major role. Inhibitors did not influence immunoreactive trypsin. Our data indicate that the variations of the serum levels of proteases and antiproteases in chronic pancreatic disease are probably independent of each other.

Is tissue polypeptide antigen more accurate than serum CEA for diagnosing pancreatic cancer?

Tissue polypeptide antigen (TPA) and carcinoembryonic antigen (CEA) were determined in the sera of 36 control subjects, 30 patients with pancreatic cancer, 35 with chronic pancreatitis and 25 with non-pancreatic digestive disease to evaluate their role in detecting pancreatic malignancy. Abnormal values of TPA and CEA were found in 28 and 19 of 30 patients with pancreatic cancer, and in four and seven of 35 patients with chronic pancreatitis, respectively. Raised titres of TPA were observed more often than equivalent serum CEA in simulated pancreatic diseases. The receiver-operating (ROC) characteristic curves showed that TPA was more discriminating than CEA in detecting pancreatic cancer. Specificity was enhanced when both titres were abnormally high and sensitivity when one titre was raised, but the diagnostic accuracy of TPA alone has not improved, which satisfactorily discriminates pancreatic cancer from chronic pancreatitis.

Determination of serum theophylline by apoenzyme reactivation immunoassay system

A reagent strip for the quantitative analysis of theophylline in serum or plasma was evaluated. The strip is based on the apoenzyme reactivation immunoassay system (ARIS) technique and is intended for use with the Ames Seralyzer reflectance photometer. The method gave CVs at three theophylline levels ranging from 3.8 to 6.3% (within run) and from 2.8 to 6.9% (day to day). The regression lines obtained from the correlation studies were y = 0.959x + 0.51 (n = 105, r = 0.9906, Sy/x = 0.56) for the comparison ARIS (y) versus Syva enzyme multiplied immunoassay (x) methods, and y = 0.986x + 0.32 (n = 105, r = 0.9832, Sy/x = 0.62) for the comparison ARIS (y) versus Abbott TDx fluorescence polarization immunoassay (x) methods. The interference from triglycerides, hemoglobin, bilirubin, and ascorbic acid, and the cross-reactivity of 8-chlorotheophylline, caffeine, 1,3-dimethyluric acid, theobromine, and 1,7-dimethylxanthine, were also investigated and discussed. The method was found to be reliable, simple, and rapid. It provides a practicable solution for immediate determinations of theophylline.

Fluorescence energy transfer immunoassay of digoxin in serum

We have evaluated the reliability of the new fluorescence energy transfer immunoassay (FETI) for determining concentrations of digoxin in serum. The method demonstrated good stability of the standard curve and satisfactory precision in both within-and between-run assay. We have also found a significant correlation between FETI and two RIA methods (r=0.97). Furthermore, the association between results by FETI and by the EMIT method (a conventional enzyme immunoassay) was a linear one. Finally, the assay encountered no significant interference from endogenous substances (hemoglobin, bilirubin , and triglycerides).

Fluorescence energy transfer immunoassay of digoxin in serum

We have evaluated the reliability of the new fluorescence energy transfer immunoassay (FETI) for determining concentrations of digoxin in serum. The method demonstrated good stability of the standard curve and satisfactory precision in both within-and between-run assay. We have also found a significant correlation between FETI and two RIA methods (r=0.97). Furthermore, the association between results by FETI and by the EMIT method (a conventional enzyme immunoassay) was a linear one. Finally, the assay encountered no significant interference from endogenous substances (hemoglobin, bilirubin , and triglycerides).

Trypsin/creatinine clearance ratio and serum immunoreactive trypsin in digestive and pancreatic diseases

The behavior of trypsin/creatinine clearance ratio (Ctr/Ccr) and serum immunoreactive trypsin (IRT) was evaluated in a total of 168 subjects with pancreatic cancer, chronic pancreatitis and non-pancreatic digestive diseases. Amylase/creatinine clearance ratio (Cam/Ccr) and serum amylase levels were also evaluated in order to establish their possible relationship with Ctr/Ccr and IRT values. Elevated Ctr/Ccr and IRT values were observed in several patients with pancreatic cancer and chronic pancreatitis. Abnormal IRT and Ctr/Ccr values were found in 28.2 and 4% of non-pancreatic digestive diseases, respectively. IRT and amylase serum levels showed consensual modifications, while Ctr/Ccr showed a behavior different from that of Cam/Ccr. Liver damage seems to play a role in increasing serum IRT levels of patients without pancreatic involvement, while the increased Ctr/Ccr seems to depend on other factors, for instance renal tubular dysfunction.