US4279994A
Expired / Lapsed
US
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Lipase determination method and reagent
Assignee: Dow Chemical Co
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Filing: 1979-07-13
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Granted: 1981-07-21
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Expires: 1999-07-13
Abstract
Abstract An improved reagent and method for determination of lipase in biological fluids utilizes an S-acyl compound as the substrate and a chromogenic sulfhydryl reagent to develop a measureable color. The improved reagent and method include a solid, water soluble pseudocholinesterase inhibitor, preferably eserine salicylate. Albumin may also included to increase sensitivity. Lipase is measured by incubating a specimen with the S-acyl compound, chromogenic sulfhydryl reagent and pseudocholinesterase inhibitor; terminating the incubation by adding a non-ionic surfactant; measuring the resulting color directly, and comparing the color to that obtained with a chemical standard solution containing an S-(2-aminoalkyl) isothiouronium salt.
Inventors
- 👤 Cleo L. Huang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:45
CPC Classifications
C; C12; C12Q; C12Q1/00; C12Q1/34; C12Q1/44; Y; Y10; Y10S; Y10S435/00; Y10S435/81
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
92 words
In a method of determining lipase activity in biological fluids by incubating a biological fluid specimen in the presence of an S-acyl compound, a chromogenic sulfhydryl reagent and a carboxyesterase inhibitor and measuring the resulting color, the improvement which comprises: (a) carying out said incubation in the presence of a diagnostically-acceptable cholinesterase/-pseudocholinesterase inhibitor in a concentration sufficient to inhibit cholinesterase and pseudocholinesterase in the specimen; (b) incubating a diagnostically-acceptable S-(aminoloweralkyl)isothiuronium salt with said S-acyl compound, chromogenic sulfhydryl reagent and said inhibitors; (c) measuring the color obtained; and (d) comparing the color measurements.
Claim 2
Dependent Claim
92 words
In a method of determining lipase activity in biological fluids by incubating a biological fluid specimen in the presence of an S-acyl compound, a chromogenic sulfhydryl reagent and a carboxyesterase inhibitor and measuring the resulting color, the improvement which comprises: (a) carying out said incubation in the presence of a diagnostically-acceptable cholinesterase/-pseudocholinesterase inhibitor in a concentration sufficient to inhibit cholinesterase and pseudocholinesterase in the specimen; (b) incubating a diagnostically-acceptable S-(aminoloweralkyl)isothiuronium salt with said S-acyl compound, chromogenic sulfhydryl reagent and said inhibitors; (c) measuring the color obtained; and (d) comparing the color measurements.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said isothiuronium salt comprises S-(2-aminoethyl)-isothiuronium bromide hydrobromide.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein the cholinesterase/pseudocholinesterase inhibitor is an eserine salt.
Claim 5
Dependent Claim
145 words
In a method for determination of lipase activity in biological fluids by incubating a biological fluid specimen in the presence of mixture of an S-acyl compound and a chromogenic sulfhydryl reagent under conditions conducive to the lipase catalyzed release of sulfhydryl groups from the S-acyl compound and formation of color on the reaction of released sulfhydryl groups with the chromogenic sulfhydryl reagent, and measuring the color produced, the improvement which comprises: (a) terminating the incubation by adding to the mixture sufficient of a non-ionic sufactant to disrupt micelles and clairfy the mixture; (b) measuring color directly in the resulting mixture; (c) carrying out said steps of incubating, terminating the incubation and measuring color with a chemical color standard comprising a predetermined amount of a diagnostically-acceptable S-(aminoloweralkyl)isothiuronium salt; and (d) comparing the color obtained with said salt and the color obtained with said biological fluid specimen.
Claim 6
Dependent Claim
145 words
In a method for determination of lipase activity in biological fluids by incubating a biological fluid specimen in the presence of mixture of an S-acyl compound and a chromogenic sulfhydryl reagent under conditions conducive to the lipase catalyzed release of sulfhydryl groups from the S-acyl compound and formation of color on the reaction of released sulfhydryl groups with the chromogenic sulfhydryl reagent, and measuring the color produced, the improvement which comprises: (a) terminating the incubation by adding to the mixture sufficient of a non-ionic sufactant to disrupt micelles and clairfy the mixture; (b) measuring color directly in the resulting mixture; (c) carrying out said steps of incubating, terminating the incubation and measuring color with a chemical color standard comprising a predetermined amount of a diagnostically-acceptable S-(aminoloweralkyl)isothiuronium salt; and (d) comparing the color obtained with said salt and the color obtained with said biological fluid specimen.
Claim 7
Dependent Claim
32 words
Method of claim 4 wherein the improvement further comprises adding sufficient acid to the mixture where the incubation is terminated to lower the pH sufficiently to inactivate lipase and stabilize the color.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-07-20 | 1985-01-19 | 1985-07-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-20 | 1989-01-19 | 1989-07-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-20 | 1993-01-19 | 1993-07-21 | $7700.00 | Window Closed / Lapsed |