PubMed · 13979071
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
K SUDO. 1962. [Correlation between serum enzyme activity and hepatic function].. https://pubmed.ncbi.nlm.nih.gov/13979071/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
We separated and characterized the enantiomers of bambuterol (5-[-(tert-butylamino)-1-hydroxyethyl]-m-phenylene-bis(dimethylcarbamate) hydrochloride), which is used in racemic form as a prodrug of terbutaline, a beta(2)-adrenoceptor agonist. The enantioseparation was attempted on several chiral HPLC columns, and the most effective separation was achieved on the amylose-based Chiralpak AD column. Since in vivo conversion of bambuterol into terbutaline involves hydrolysis by butyrylcholinesterase (EC 3.1.1.8), we studied the reaction of enantiomers with eight human BChE variants. Both enantiomers inhibited all studied BChE variants; however, the rate of inhibition with the (R)-enantiomer was about five times faster than with the (S)-enantiomer. (R)-bambuterol inhibition rate constants for homozygous usual (UU), fluoride-resistant (FF) or atypical (AA) variant ranged from 6.4 to 0.11 min(-1)microM(-1). The inhibition rates for heterozygotes were between the respective constants for the corresponding homozygotes.
Pancuronium bromide (PCBr) inhibition effect on enzyme cholinesterase from pooled human serum (Che, EC 3.1.1.8 acylcholine acylhydrolase) was used for development of a spectrophotometric kinetic method for PCBr determination in human serum and urine. Optimal conditions for the basic and inhibitor reactions were established: pH=7.7 and substrate concentration c(benzoylcholine chloride)=1.33 mmol/L. Kinetic parameters were also determined: Michaelis-Menten's constant K(M)=0.40 mmol/L, maximal reaction rate V(max)=52.2 micromol/L min, inhibition constant K(i)=0,56 micromol/L and IC(50)=1.31 micromol/L. Linear dependence between the reaction rate and inhibitor concentration exists in PCBr concentration range 8.20-68.25 nmol/L, which corresponds to the real sample concentrations from 0.328 to 2.730 micromol/L. The method detection and quantification limits were 2.01 nmol/L and 6.67 nmol/L, respectively. Precision of the method was tested for three pancuronium concentrations (10.70, 29.35 and 51.25 nmol/L). Relative standard deviation (RSD) was in the range 0.15-7.45%. Accuracy was examined by standard addition method. Influence of the substances usually present in serum and urine on the reaction rate was tested. The developed method was applied for PCBr content determination in serum model samples, urine model samples and in urine taken during surgery. The method has good sensitivity, accuracy, precision and it is suitable for clinical practice.
The effect of cancer on acetyl- (AChE) and butyrylcholinesterase (BuChE) activities of human gut was investigated. ChE activity was measured in 55 paired samples of healthy and malignant colon, sigmoid colon and rectum. Cancer decreases the mean AChE activity value from 2.17 +/- 1.07 to 1.40 +/- 0.89 mU/mg (p < 0.001), and BuChE activity from 4.16 +/- 2.41 to 1.65 +/- 0.87 mU/mg (p < 0.001). AChE monomers and dimers (light forms), and less asymmetric and tetrameric variants (heavy forms) were identified in gut. The proportions of the heavy species dropped in malignant colon. Since muscarinic stimulation is needed for human colon cancer cell proliferation, the fall of ChE activity in neoplastic colon, with the increased availability of acetylcholine, may increase tumour growth.