A METHOD FOR THE DETECTION OF ATYPICAL FORMS OF HUMAN SERUM CHOLINESTERASE. DETERMINATION OF DIBUCAINE NUMBERS

1957 ◽  
Vol 35 (1) ◽  
pp. 339-346 ◽  
Author(s):  
W. Kalow ◽  
K. Genest
Keyword(s):  
Human Serum ◽  
Local Anaesthetic ◽  
Phosphate Buffer ◽  
Esterase Activity ◽  
Experimental Temperature ◽  
Serum Cholinesterase ◽  
Good Discrimination ◽  
Esterase Inhibition ◽  
Recording Spectrophotometer

Cases with atypical esterase activity were found by determining esterase inhibition in numerous sera. A suitable inhibitor was the local anaesthetic dibucaine (cinchocaine, TN Nupercaine, Perkain). A good discrimination between typical and atypical sera was obtained under the following conditions: The esterase activity of human serum diluted 1:100 was measured with a recording spectrophotometer at 240 mμ. The substrate was 5 × 10−5 M benzoylcholine dissolved in M/15 phosphate buffer, pH 7.4. The concentration of the inhibitor was 10−5 M. With the experimental temperature around 25 °C, the average inhibition of the typical enzyme was 78.8 ± 0.3%. The inhibition of the atypical esterases was less; in rare cases the inhibition was only 16%. For each person, the inhibition characteristics were constant over a period of several months, and independent of the esterase level. The degree of inhibition measured under these conditions and expressed in per cent has been termed "Dibucaine Number".

A METHOD FOR THE DETECTION OF ATYPICAL FORMS OF HUMAN SERUM CHOLINESTERASE. DETERMINATION OF DIBUCAINE NUMBERS

1957 ◽  
Vol 35 (6) ◽  
pp. 339-346 ◽  
Author(s):  
W. Kalow ◽  
K. Genest
Keyword(s):  
Human Serum ◽  
Local Anaesthetic ◽  
Phosphate Buffer ◽  
Esterase Activity ◽  
Experimental Temperature ◽  
Serum Cholinesterase ◽  
Good Discrimination ◽  
Esterase Inhibition ◽  
Recording Spectrophotometer

Cases with atypical esterase activity were found by determining esterase inhibition in numerous sera. A suitable inhibitor was the local anaesthetic dibucaine (cinchocaine, TN Nupercaine, Perkain). A good discrimination between typical and atypical sera was obtained under the following conditions: The esterase activity of human serum diluted 1:100 was measured with a recording spectrophotometer at 240 mμ. The substrate was 5 × 10−5 M benzoylcholine dissolved in M/15 phosphate buffer, pH 7.4. The concentration of the inhibitor was 10−5 M. With the experimental temperature around 25 °C, the average inhibition of the typical enzyme was 78.8 ± 0.3%. The inhibition of the atypical esterases was less; in rare cases the inhibition was only 16%. For each person, the inhibition characteristics were constant over a period of several months, and independent of the esterase level. The degree of inhibition measured under these conditions and expressed in per cent has been termed "Dibucaine Number".

scholarly journals A simple method for the determination of the cholesterol esterase activity.

2013 ◽  
Vol 60 (3) ◽  
Author(s):  
Agnieszka Ewa Stępień ◽  
Mykhailo Gonchar
Keyword(s):  
Human Serum ◽  
Esterase Activity ◽  
Cholesterol Oxidase ◽  
Cholesterol Esterase ◽  
Cholesterol Esters ◽  
Simple Method ◽  
Bacterial Enzyme ◽  
Low Costs ◽  
Hydrolysis Of

The proposed method determines the activity of cholesterol esterase (CEH) and takes advantage of its ability to catalyze the hydrolysis of cholesterol esters naturally present in human serum. The assay is based on Allain's method of spectrophotometric determination of cholesterol by means of cholesterol oxidase, peroxidase, but using 3,5-dichloro-dihydroxybenzenesulfonic acid (DHBS) as phenolic chromogen and human serum as a source of substrate for the CEH as a novelty. Furthermore, it is characterized by low costs and high precision. It can be employed to control the activity of CE preparations used for the preparation of enzymatic kits for the determination of cholesterol or for screening of potential bacterial enzyme producers.

Hydrophobicity on Esterase Activity of Human Serum Cholinesterase

1995 ◽  
pp. 123-124
Author(s):  
L. Jaganathan ◽  
K. Padmalatha ◽  
G. Revathi ◽  
R. Boopathy
Keyword(s):  
Human Serum ◽  
Esterase Activity ◽  
Serum Cholinesterase

Detoxification of organophosphates by A-esterases in human serum

1999 ◽  
Vol 18 (11) ◽  
pp. 653-658 ◽  
Author(s):  
C Sams ◽  
H J Mason
Keyword(s):  
Human Serum ◽  
Esterase Activity ◽  
Dose Effect ◽  
Interindividual Variation ◽  
Serum Cholinesterase ◽  
Calcium Dependent ◽  
Spectrophotometric Methods ◽  
Relative Ability ◽  
Serum Inhibition

1 In vitro detoxification of the organophosphate (OP) insecticides paraoxon, chlorpyrifos-oxon and malaoxon has been investigated in human serum. 2 Specific A-esterase activity to each OP substrate was measured in the serum of 100 individuals using established spectrophotometric methods for paraoxonase and chlorpyrifos-oxonase and a novel assay for malaoxonase activity. 3 Dose-effect inhibition of serum cholinesterase by the three OPs was measured in pooled human serum. Inhibition of calcium dependent A-esterases by addition of EDTA resulted in increased inhibition of cholinesterase at a given OP concentration. 4 Data from both the direct spectrophotometric measurement of A-esterase activity and inhibition of serum cholinesterase in the presence and absence of Aesterase activity indicated that human serum Aesterase catalysed detoxification of chlorpyrifosoxon4 paraoxon4 malaoxon. Our data also confirms the wide variation in potency to inhibit cholinesterase between the three OPs. 5 Malaoxonase activity in human serum does not appear to be polymorphic, however, there is large interindividual variation as has been previously found for other A-esterases. 6 This study has demonstrated two approaches to investigate the inter-individual variation towards specific OPs and the relative ability of human serum A-esterase to detoxify specific OP compounds.

Spectrophotometric Determination of Factor Xa Generation in Factor IX Concentrates

1977 ◽  
Vol 37 (03) ◽  
pp. 535-540 ◽  
Author(s):  
D. S Pepper ◽  
D Banhegyi ◽  
Ann Howie
Keyword(s):  
Intrinsic Factor ◽  
Factor Xa ◽  
Factor Ix ◽  
Factor V ◽  
Factor X ◽  
Generation Times ◽  
Incubation Periods ◽  
Multiple Sample ◽  
Recording Spectrophotometer

SummaryPrevious work from this department, concerned with testing the potential thrombogenicity of therapeutic factor IX concentrates, demonstrated that following recalcification of factor IX concentrates thrombin was generated within 3-30 minutes of incubation (Sas et al. 1975). The test developed (known as the TGt 50 test) is a two-stage assay and was thus found to be time consuming, tedious and tended to become inaccurate with long incubation periods and a large number of samples. A semiautomatic version of the test is reported in which the synthetic peptide Bz-ILE-GLU-GLY-ARG-pNA (S-2222) is added to recalcified, diluted factor IX concentrate in the micro-cuvette of a multiple sample recording spectrophotometer. Information can be obtained on (a) the amount of Xa (if any) present prior to recalcification (b) the initial amount of Xa formed and (c) the time taken to activate all factor X to Xa. Direct graphical interpretation shows a number of qualitative differences between commercial preparations, but by either of the criteria (b) or (c) above, it is possible to place the different products into “activated” and “non activated” groups such that both the Xa generation times and TGt 50 tests identify the same two groups of products. This agreement also indicates that the TGt 50 test is independent of the intrinsic factor V levels in the various concentrates.

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