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V Brock

Publications and source records attributed to V Brock.

5 recordsLinked to original sources
PubMed1993

Factors affecting inter-individual variation in human plasma cholinesterase activity: body weight, height, sex, genetic polymorphism and age.

The influence of body weight, height, age and sex on plasma cholinesterase activity (ChE) in 650 males and 437 females with ChE-1 phenotype U (genotype ChEuChEu or ChEuChEs) or UA (genotype ChEuChEa) was studied in a multiple regression model. ChE was not influenced by age (p > 0.01), but, like other liver synthesized plasma enzymes, highly (p < 0.001) influenced by body weight and height. In a logarithmic scale ChE followed a linear model (R = 0.535, p < 0.001) with randomly distributed residuals, InChE = 3.286-0.308 x ChE-1 phenotype-0.104 x sex + 0.00765 x weight - 0.00723 x height (U = 1, UA = 2; male = 1, female = 2; kg; cm). A simplified model based on body-mass index (BMI = weight divided by squared height, kg/m2), InCHE = 2.016-0.308 x ChE-1 phenotype - 0.091 x sex + 0.0230 x BMI, showed the same goodness-of-fit (R = 0.533). In a non-logarithmic scale both multiple regression models failed to fit cases with high ChE activity. A model for a 'standardized' plasma ChE in which the effects of ChE-1 phenotype, sex, body weight and height are eliminated, is proposed to compare ChE in unmatched population groups when using this enzyme activity as a biomarker in environmental or occupational medicine.

Adolescent↗
PubMed1990

Plasma cholinesterase activity in a healthy population group with no occupational exposure to known cholinesterase inhibitors: relative influence of some factors related to normal inter- and intra-individual variations.

Inter-individual variations of plasma cholinesterase were analysed in 193 apparently healthy volunteers (122 males, 71 females) with no known occupational exposure to cholinesterase inhibitors. Multiple regression analysis and analysis of variance showed statistically significant effects on the individual plasma cholinesterase activity by body weight, height, sex, and ChE-1 phenotype (but not by age or electrophoretic phenotype). Varying body weight explained one-fourth of the observed biological variance (s2total). The intra-individual variations during an 8-month period varied substantially from one individual to another (3% to 41% of the subject's mean activity); a repeated-measures analysis of variance showed a within-person variance (s2intra) = 5% of s2total. Intra-individual variation was uninfluenced by the variables that influence the inter-individual variance. A model for a 'standardized' plasma cholinesterase in which the combined effects of the four significant variables, ChE-1 phenotype, sex, body weight, and height are eliminated, is proposed for comparisons of plasma cholinesterase activities in unmatched population groups, e.g. within environmental or occupational medicine.

Adult↗