Butyrylcholinesterase Activity Levels Research Articles

Association between cholinesterase activity and critical illness brain dysfunction

BackgroundDelirium is a frequent manifestation of acute brain dysfunction and is associated with cognitive impairment. The hypothesized mechanism of brain dysfunction during critical illness is centered on neuroinflammation, regulated in part by the cholinergic system. Point-of-care serum cholinesterase enzyme activity measurements serve as a real-time index of cholinergic activity. We hypothesized that cholinesterase activity during critical illness would be associated with delirium in the intensive care unit (ICU) and cognitive impairment after discharge.MethodsWe enrolled adults with respiratory failure and/or shock and measured plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity on days 1, 3, 5, and 7 after enrollment. AChE values were also normalized per gram of hemoglobin (AChE/Hgb). We assessed for coma and delirium twice daily using the Richmond Agitation Sedation Scale and the Confusion Assessment Method for the ICU to evaluate daily mental status (delirium, coma, normal) and days alive without delirium or coma. Cognitive impairment, disability, and health-related quality of life were assessed at up to 6 months post-discharge. We used multivariable regression to determine whether AChE, AChE/Hgb, and BChE activity were associated with outcomes after adjusting for relevant covariates.ResultsWe included 272 critically ill patients who were a median (IQR) age 56 (39–67) years and had a median Sequential Organ Failure Assessment score at enrollment of 8 (5–11). Higher daily AChE levels were associated with increased odds of being delirious versus normal mental status on the same day (Odds Ratio [95% Confidence Interval] 1.64 [1.11, 2.43]; P = 0.045). AChE/Hgb and BChE activity levels were not associated with delirious mental status. Lower enrollment BChE was associated with fewer days alive without delirium or coma (P = 0.048). AChE, AChE/Hgb, and BChE levels were not significantly associated with cognitive impairment, disability, or quality of life after discharge.ConclusionCholinesterase activity during critical illness is associated with delirium but not with outcomes after discharge, findings that may reflect mechanisms of acute brain organ dysfunction.Trial Registration: NCT03098472. Registered 31 March 2017.

Determination Effects of Rheum ribes L. against High Calorie Diet-induced Obesity: Investigation of Changes in Immunologic and Neurologic Enzymes Activities

This study was carried out to investigate the immunotoxic and neurotoxic effects of Rheum ribes L. (Rr) plant extract on liver, brain and heart tissues in rats with an experimental obesity model. Wistar albino male rats were used in the study. In this study, 4 groups were formed, one of which was the control group, and each group consisted of 6 rats. The groups were the ''control (CG)'', ''high calorie diet (HCD) control (HCDG)'', 'HCD + Rr (200 mg/kg) (HCDRHE1)'' and ''HCD + Rr (400 mg/kg) (HCDRHE2)''. At the end of the study, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), adenosineaminase (ADA) and myeloperoxidase (MPO) biomarkers were evaluated in tissues. According to the study findings, the ADA and MPO activity levels of the obese group increased significantly compared to the control group, and these enzyme levels in the groups administered Rr plant extract approached the control group levels. On the other hand, the AChE and BChE activity levels of the obese group decreased compared to the control group, and there was a statistically significant increase in the groups administered plant extracts compared to the control group. In conclusion, Rr plant root extract suppresses neurotoxicity and immunotoxicity in rats with obesity induced by a high-calorie diet (HCD).

Pesticide-induced changes in cholinesterase activity and chronic kidney disease of unknown etiology among farmers in Nakhon Ratchasima, Thailand

Chronic kidney disease of unknown etiology (CKDu) has emerged agricultural population. This study aimed to obtain a prevalence of cholinesterase activity and CKDu, and evaluate factors associated with organophosphate (OP) and carbamate (CA) poisoning and CKDu among farmers in Nakhon Ratchasima province, Thailand. A cross-sectional study was conducted among 58 farmers, with data collected using a structured questionnaire. Blood and urine samples were collected for analysis of erythrocyte acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), serum creatinine (SCr), and urinary creatinine (UCr). Farmers who had CKD without diabetes, hypertension, proteinurea, and other traditional causes were classified as CKDu. The average age (± SD) was 49.22(± 6.87) years. The prevalence of abnormal AChE and BuChE activity levels were 55.17% and 46.55%, respectively. In kidney function, the prevalence of abnormal UCr was 17.24% and CKDu was 24.14%. In adjusted model, the type of pesticide sprayer and personal protective equipment used were significantly associated with CKDu (bivariate analysis, p < 0.05). Using multivariate analysis, OP and CA poisoning were significantly associated with a 4.703-fold higher risk of CKDu (95% CI = 1.020-21.686). Farmers who applied OP and CA pesticides had decreased kidney function. These findings might be beneficial in reducing the adverse effects pesticide exposure and CKDu prevention.

Characterization of four BCHE mutations associated with prolonged effect of suxamethonium.

Butyrylcholinesterase (BChE) deficiency is characterized by prolonged apnea after the use of muscle relaxants (suxamethonium or mivacurium) in patients who have mutations in the BCHE gene. Here, we report the characterization of four BCHE mutations associated with prolonged effect of suxamethonium (amino acid numbering based on the matured enzyme): p.20delValPheGlyGlyThrValThr, p.Leu88His, p.Ile140del and p.Arg386Cys. Expression of recombinant BCHE mutants, kinetic analysis and molecular dynamics were undertaken to understand how these mutations induce BChE deficiency. Three of the mutations studied (p.20delValPheGlyGlyThrValThr, p.Ile140del and p.Arg386Cys) lead to a "silent" BChE phenotype. Recombinant BCHE expression studies for these mutants revealed BChE activity levels comparable to untransfected cells. Only the last one (hBChE-L88H) presented BChE activity in the transfected cell culture medium. This BChE mutant (p.Leu88His) is associated with a lower kcat value compare to the wild-type enzyme. Molecular dynamics simulations analyses suggest that a destabilization of a structure implicated in enzyme activity (Ω-loop) can explain the modification of the kinetic parameter of the mutated protein.

Drop of Butyrylcholinesterase Activity after Cyclophosphamide Conditioning as a Predictive Marker of Liver Transplant-Related Complications and Its Correlation with Transplant-Related Mortality in Pediatric Hematopoietic Stem Cell Recipients.

Transplant-related liver complications are a potentially fatal condition of hematopoietic stem cell transplantation (HSCT) in pediatric patients, actually representing one of the main factors involved in transplant-related mortality (TRM). The search for a specific marker capable of predicting the development of this condition is a relevant clinical issue. We have observed a variable reduction in serum butyrylcholinesterase (BChE) activity after a cyclophosphamide-containing conditioning regimen. This study aims to determine the cutoff of BChE activity reduction that might be a specific prognostic marker for liver complications after HSCT. Our results show that the reduction of BChE values below 2000 U/L the day before the transplantation is an indicator strongly associated with the transplant-related liver complications (p < 0.0001). The incidence of overall survival at 1 year was significantly higher in the BChE > 2000 U/L group compared to the BChE < 2000 U/L group (84.7% versus 58.5%, p < 0.001), while the TRM rate was significantly lower (8.1% versus 23.1%, p < 0.05). None of the patients undergoing prophylaxis with defibrotide developed severe liver complications. Starting defibrotide treatment at the first signs of hepatic dysfunction in patients with particularly low BChE activity levels reduces severe liver transplant-related complications.

In Vivo Effects of Neostigmine and Physostigmine on Neutrophil Functions and Evaluation of Acetylcholinesterase and Butyrylcholinesterase as Inflammatory Markers during Experimental Sepsis in Rats.

Introduction Recent studies have shown that acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) may serve as important diagnostic and therapeutic targets in sepsis. Since polymorphonuclear neutrophils (PMNs) play a pivotal role in the early phase of sepsis, we evaluated the potential therapeutic effects of cholinesterase inhibitors on PMN functions during cecal ligation and puncture- (CLP-) induced sepsis and investigated the roles of AChE and BChE as inflammatory markers under standardized experimental conditions. Methods Sham surgery or CLP was performed in male Wistar rats (n = 60). Animals were randomized into four groups: physostigmine, 100 μg/kg; neostigmine, 75 μg/kg; 0.9% saline (control group); and sham group, each applied four times over 24 h. The levels of reactive oxygen species (ROS) production and CD11b/CD62l expression were quantified by flow cytometry at t = 0, 6, 15, 20, and 24 h. Blood gas analysis as well as AChE and BChE activity levels was measured by validated point-of-care measurements. Clinical scores and survival times were determined. Results CLP induced a significant increase in ROS production and CD11b upregulation by rat PMNs. Treatment with physostigmine or neostigmine significantly reduced ROS production and CD11b upregulation by PMNs 20 h after CLP induction. In physostigmine-treated animals, survival times were significantly improved compared to the control animals, but not in neostigmine-treated animals. While AChE activity significantly decreased in the control animals at t > 6 h, AChE activity did not change in the sham group. BChE activity decreased at t > 20 h in the control animals. Conclusion While AChE activity may serve as an acute inflammatory marker, BChE activity shows a delayed decrease. Administration of centrally acting physostigmine in CLP-induced sepsis in rats has protective effects on PMN functions and improves survival times, which may be of interest in clinical practice.

Clinical associations between acetylcholine levels and cholinesterase activity in saliva and gingival crevicular fluid and periodontal diseases.

The oral mucosa possesses a non-neuronal cholinergic system. This study aimed to determine clinical evidence for a role of cholinergic mechanisms in the pathogenesis of periodontal diseases. Fifty healthy participants, 52 patients with gingivitis and 49 with periodontitis were recruited. Full periodontal parameters were recorded and saliva and gingival crevicular fluid (GCF) collected. Levels of acetylcholine and inflammatory mediators were quantified using commercially available assay kits. Acetylcholinesterase and butyrylcholinesterase activities were measured using a published biochemical assay. Acetylcholine levels are significantly elevated in saliva and GCF, whereas GCF levels of butyrylcholinesterase activity are significantly decreased, in patients with periodontal diseases. Acetylcholine levels in saliva and GCF correlated positively with clinical markers of disease severity and with increased levels of IL-17A and IL-17F. In contrast, butyrylcholinesterase activity levels in GCF showed significant negative correlations with clinical markers of disease severity and IL-17A and IL-17F levels. None of the findings were due to smoking. Elevated acetylcholine levels and reduced butyrylcholinesterase activity are clinically associated with periodontal diseases and elevated levels of IL-17A and IL-17F. Therefore, non-neuronal cholinergic mechanisms may influence IL-17 biology and the aetiopathogenesis of periodontal diseases and therefore are possible therapeutic targets.

Pesticide exposure and subjective symptoms of cut-flower farmers.

Sales of cut-flowers depend much on the outer appearance of the flowers. They are not intended to be used as foodstuffs; thus, pesticides are used more liberally for cut flower growing than for other agricultural products. Flower production is often carried out in greenhouses; therefore, pesticide exposure seems to reach not only the person spraying the pesticides, but also the non-spraying workers as well. In 2009, a special research project on pesticide poisoning, affiliated with the Japanese Association of Rural Medicine, developed a study that focused on cut-flower farmers’ exposure to pesticide, subsequent adverse symptoms experienced, and treatment modalities to relieve pesticide-related symptoms. In this group of farmers, the pesticide sprayers were almost entirely male, while the females did not do any spraying. The organophosphate metabolite level in the urine of the males was higher than that of the females. However, in the female group, a positive relation was found between average working times in the greenhouse, and urine concentration of dialkylphosphates. In 2 males of this group, the level of dimethylphosphate was detected at 1,000 times the median level. Their butyrylcholinesterase activity levels on the day of testing had declined to 64%, 72% of their average level of the proximate 4 years, respectively. Communication with these subjects regarding pesticide exposure and methods of prevention appeared to be an effective approach for reducing symptom severity. Among soil fumigants, chloropicrin and 1,3-dichloropropene were most often used. Difficulty breathing was one of the subjective symptoms associated with chloropicrin, as well as watery eyes, coughing, and runny nose. These symptoms were effectively suppressed by the preventative practice of wearing gas masks and goggles while using soil fumigants. It would be beneficial to strongly encourage use of suitable protective gear among farmers exposed to soil fumigants.

Surrogate markers of the kidney and liver in the assessment of gestational diabetes mellitus and fetal outcome.

To investigate whether serum levels of butyrylcho-linesterase activity, cystatin C, and pre-albumin has the potential value as γ-glutamyl transferase in reflecting gestational diabetes mellitus and its fetal outcome. Seventy-six gestational diabetes mellitus women and 76 pregnancies with normal glucose tolerance in the second trimester were enrolled. Maternal serum parameters of butyrylcholinesterase activity, γ-glutamyl transferase, cystatin C, and pre-albumin were detected and evaluated. The pregnant complications and fetal outcome were also evaluated. Levels of butyrylcholinesterase activity, γ-glutamyl transferase, cystatin C, pre-albumin and glycemic variables were higher in the gestational diabetes mellitus patients than in the controls. Levels of butyrylcholinesterase activity were significantly correlated to the levels of fasting plasma glucose, cystatin C, and γ- glutamyl transferase (p < 0.05) in the gestational diabetes mellitus group. There were statistical differences in cases of preterm delivery, preeclampsia and postpartum hemorrhage. Higher levels of γ-glutamyl transferase and pre-albumin were risk markers for gestational diabetes mellitus (p < 0.05). The diagnosis curve demonstrated that γ-glutamyl transferase had a significant advantage over other markers (p < 0.001) but no significance compared with pre-albumin (p = 0.096). None of the detected markers showed predictive value for fetal outcome. Serum levels of butyrylcholinesterase activity, γ-glutamyl transferase, cystatin C and pre-albumin were correlated with gestational diabetes mellitus status but not with the fetal outcome. Pre-albumin can be equivalent as γ-glutamyl transferase in reflecting the presence of gestational diabetes mellitus.

Blood acetylcholinesterase and butyrylcholinesterase as biomarkers of cholinesterase depression among pesticide handlers

ObjectiveAgricultural pesticide handlers are at an elevated risk for overexposure to organophosphate (OP) pesticides, but symptoms can be difficult to recognise, making biomarkers invaluable for diagnosis. Occupational monitoring programmes for...

In vitroinhibition of blood cholinesterase activities from cattle by triazole fungicides

The changes in cattle acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities after exposure to tebuconazole-based fungicides (Orius and Prosaro®) in vitro were determined spectrophotometrically according to the Ellman method. The fungicides induced the decrease in AChE and BChE levels in a dose-dependent manner. Statistically significant inhibition of erythrocyte AChE levels was observed in the concentration range from 150 to 300 μg ml−1 (p < 0.001) for Orius and from 100 to 300 μg ml−1 for Prosaro® (p < 0.01 and p < 0.001, respectively). Levels of BChE activity were more reduced for the fungicide Orius (40–50%) than for Prosaro®. Statistical significance in the inhibition of BChE activity was found after exposure of cattle plasma to both fungicides at concentrations starting from 150 μg ml−1 (p < 0.001). Our results indicate that tebuconazole-based fungicides are able to reduce cattle AChE and BChE activities.

Effects of Tetra‐Alkyl Bis‐Phosphates on Butyrylcholinesterase

The progression of Alzheimer's Disease (AD) correlates positively with increasing levels of butyrylcholinesterase activity. As such, the inhibitors of this enzyme provide promise as potential therapeutics. Bisphosphates were evaluated for their inhibitory effects on the enzyme. The compounds were synthesized by the reaction of the corresponding dialkyl chlorophosphate with the appropriate diol in pyridine and dicholoromethane under inert conditions. The crude products were purified by flash chromatography to give the desired bisphosphates high purity. IC50's for the tetraethyl and tetrabutyl hexyl derivatives were determined to be 2.52 μM and 0.95 μM, respectively. The significance of the hexyl diphosphates’ inhibitory properties is highlighted when compared to the single phosphate derivative, diethyl hexyl phosphate, which showed little inhibitory activity. Moreover, analysis of the enzyme inhibition suggests that there are two binding sites, each with separate affinities. Modification of the carbon‐chain linker to produce shorter and longer bisphosphates produced an apparent increase in enzyme activity. The molecules used were tetraethyl‐3‐oxypentyl‐bisphosphate and 1,8‐bis(diethylphosphoryl)octane.

Activity levels of B-esterases in the tadpoles of 11 species of frogs in the middle Paraná River floodplain: Implication for ecological risk assessment of soybean crops

Soybean fields provide habitats for many species of amphibians. However, the persistence and health of amphibian populations may be at risk from the increasing use of pesticides and other agricultural chemicals. We examined the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carboxylesterases (CbEs) in 11 syntopic species of larval anurans. In vitro effects of malaoxon causing 50% BChE inhibition (IC 50) were also studied. In addition, we calculated a relative risk index (RI) based on the geographic distributions of the anurans, the phenology of soybean cultivation, and basal enzymatic values related to potential pesticide detoxification. Among the 11 species, AChE activity varied from 17.5±1.6 to 68.2±4.7 nmol min −1 mg −1 protein (PT). BChE activity also varied significantly, ranging from 3.3±0.4 to 7.5±0.4 nmol min −1 mg −1 PT. Both measures of CbE activities varied widely (CbE α-NA: 2.1±0.5–12.4±1.1 nmol min −1 mg −1 PT; CbE-4NPV: 21.8±1.8–102.6±7.9 nmol min −1 mg −1 PT). We also corroborate that lower BChE activity levels for the tadpoles were associated at minor IC 50 values. The results of this study demonstrate significant variation in enzymatic levels among several tadpole species and intermediate to high RI values for 7 species. Based on these results, it appears that a conversion of native ecosystems to soybean crops may lead to increased ecological risk for anuran amphibians.

Intrathecal delivery of fluorescent labeled butyrylcholinesterase to the brains of butyrylcholinesterase knock-out mice: Visualization and quantification of enzyme distribution in the brain

Exogenously delivered butyrylcholinesterase (BChE) has proven to be an efficient bioscavenger against highly toxic organophosphorus poisons and nerve agents. The scavenger properties of BChE when delivered via intramuscular, intravenous, subcutaneous, or intraperitoneal routes are limited to the body's peripheral sites because the 340 kDa enzyme does not cross the blood–brain barrier (BBB). Overcoming the BBB is an important step toward evaluating the neuroprotective properties of BChE within the central nervous system (CNS). This study examines the feasibility of delivering BChE to the brain and spinal cord by intrathecal (IT) injection. Mice completely devoid of BChE were injected intrathecally with either BChE (80 units) that was labeled with near-infrared fluorescent dye (BChE/IRDye) or a molar equivalent amount of carboxylate dye. The BChE/IRDye and carboxylate dye were tracked using an in vivo imaging system demonstrating the real-time distribution of BChE in the brain and the residence time in the brain and spinal cord through 25 h post-dosing. BChE/IRdye levels in the brain peaked at 6 h post-dosing. BChE enzyme activity was quantified in plasma and brain sections by BChE activity assays of plasma and of perfused tissues. Average BChE activity levels were 0.6 units/g in the brains of mice treated with BChE/IRDye at 4 h post-dosing. Intense fluorescent signal in the cortex, dentate gyrus and ventricles of the brain at 25 h post-dosing was visualized by confocal microscopy and the presence of BChE was confirmed with activity assays of frozen sections. This procedure proved to be an efficient, safe and rapid method to deliver BChE to the CNS of mice, providing a research tool for determining neural protection by BChE following OP exposure.

Levels of plasma B-esterases and glutathione-S-transferase activities in three South American toad species

We determined the normal levels of butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferases (GST) activities in three South American toad species in order to establish reference values for field pesticide monitoring purposes. Interspecies variations in B-esterase and GST activities were examined according to body mass. In addition, comparative inhibition of BChE and CbE activities using malaoxon, and chemical reactivation of malaoxon-inhibited BChE activity using pyridine-2-aldoxime methochloride (2-PAM) were investigated. Bufo fernandezae had average activity values for BChE: 17.31 mmol min−1 ml−1; CbE: 621.49 nmol min−1 ml−1 and GST: 1.94 mmol min−1 ml−1 while B. arenarum enzymatic average activities were BChE: 9.51 mmol min−1 ml−1; CbE: 270.07 nmol min−1 ml−1, and GST: 1.59 mmol min−1 ml−1; finally Bufo schneideri had enzymatic mean values of BChE: 2.08 mmol min−1 ml−1; CbE: 301.95 nmol min−1 ml−1, and GST: 1.60 mmol min−1 ml−1. Moreover, we found an allometric relationship between plasma BChE and CbE activities and body size for the three toad species. We suggest that B. fernandezae would be the species with a higher tolerance capacity to organophosphorous insecticides compared to the other toad species, while B. schneideri may be the most vulnerable toad species to field pesticide exposure, although some other factors (e.g., brain AChE sensitivity or pesticide metabolism by phosphotriesterases) should be also taken into account. The malaoxon-inhibited BChE activity of the three toad species was reactivated in the presence of 2-PAM, and it is recommended as a specific and sensitive methodology in the assessment of field exposure to OP insecticides together to compare BChE activity levels between OP-exposed and nonexposed individuals.

Evaluating reptile exposure to cholinesterase‐inhibiting agrochemicals by serum butyrylcholinesterase activity

Blood samples from lizards (Gallotia galloti) collected from two agricultural areas (Las Galletas and Punta del Hidalgo) and two reference areas on the Island of Tenerife (Canary Islands, Spain) were analyzed for butyrylcholinesterase (BChE) activity. Serum BChE activity was characterized first by in vitro experiments using selective substrates and inhibitors. Of the total cholinesterase (ChE) activity, 74% could be attributed to BChE activity. This portion of the total ChE activity was inhibited dose dependently by tetraisopropyl pyrophosphoramide and hydrolyzed the substrate butyrylthiocholine iodide. No enzyme inhibition was observed at high substrate concentration. Twenty-one lizards collected from agricultural sampling sites showed significant inhibition (p < 0.001) of BChE activity (mean +/- standard deviation [SD] of 4.66 +/- 2.63 micromol/min/ml for lizards from Las Galletas and 5.13 +/- 1.48 for lizards from Punta del Hidalgo) compared with BChE activity for lizards from the reference sites (6.35 +/- 1.75 micromol/min/ ml). Las Galletas had the highest number of lizards (22%) with significantly inhibited BChE activity. In vitro assays showed that 10(-4) M pyridine-2-aldoxime methochloride (2-PAM) reactivated dichlorvos- or paraoxon-inhibited BChE activity within a 60-min incubation period. Almost all serum samples with depressed BChE activity that were collected from lizards from agricultural areas responded to 2-PAM reactivation of enzyme activity (8-60% increase in enzyme activity). Reactivation by treatment with 2-PAM confirmed that the depression of BChE activity was attributable to organophosphorus (OP) compounds. Evaluation of BChE activity levels and the chemical reactivation of serum BChE activity in G. galloti using 2-PAM was found to be a sensitive indicator of G. galloti exposure to OP compounds.

Production of butyrylcholinesterase by Caco-2 cells: lack of relationship with triglyceride production.

Elevated levels of butyrylcholinesterase activity occur under a number of hypertriglyceridemic conditions, including diabetes and obesity. This study examines whether butyrylcholinesterase activity has a direct effect on triglyceride production, using Caco-2 cells, a human intestinal adenocarcinoma cell line. Caco-2 cells were incubated with 500 microM oleate to stimulate triglyceride production, and butyrylcholinesterase activity was measured in the cellular homogenate. Butyrylcholinesterase activity was approximately 3 x 10(-3) micromol/min per milligram protein. Although triglyceride production increased by almost five-fold after 18 h of stimulation with oleate, butyrylcholinesterase activity was not increased. Furthermore, inhibition of butyrylcholinesterase activity using 1 mM tetraisopropylpyrophosphoramide did not significantly affect triglyceride production or secretion. Human insulin (100 microU/ml) increased the production of butyrylcholinesterase without increasing triglyceride production. This demonstrates that stimulation of fatty acid production and butyrylcholinesterase activity occur by independent mechanisms and suggests that their correlation in hyperlipidemic conditions is not due to a direct relationship in production in situ.

Abundant tissue butyrylcholinesterase and its possible function in the acetylcholinesterase knockout mouse.

We have described recently an acetylcholinesterase (AChE) knockout mouse. While comparing the tissue distribution of AChE and butyrylcholinesterase (BChE), we found that extraction buffers containing Triton X-100 strongly inhibited mouse BChE activity. In contrast, buffers with Tween 20 caused no inhibition of BChE. Conventional techniques grossly underestimated BChE activity by up to 15-fold. In Tween 20 buffer, the intestine, serum, lung, liver, and heart had higher BChE than AChE activity. Only brain had higher AChE than BChE activity in AChE +/+ mice. These findings contradict the dogma, based mainly on observations in Triton X-100 extracts, that BChE is a minor cholinesterase in animal tissues. AChE +/- mice had 50% of normal AChE activity and AChE -/- mice had none, but all mice had similar levels of BChE activity. BChE was inhibited by Triton X-100 in all species tested, except rat and chicken. Inhibition was reversible and competitive with substrate binding. The active site of rat BChE was unique, having an arginine in place of leucine at position 286 (human BChE numbering) in the acyl-binding pocket of the active site, thus explaining the lack of inhibition of rat BChE by Triton X-100. The generally high levels of BChE activity in tissues, including the motor endplate, and the observation that mice live without AChE, suggest that BChE has an essential function in nullizygous mice and probably in wild-type mice as well.

Identification of a point mutation associated with a silent phenotype of human serum butyrylcholinesterase – a case of familial cholinesterasemia

A point mutation which caused a silent phenotype of human serum butyrylcholinesterase (BChE) was identified in the DNA of a 47-year- old Japanese woman who visited our hospital complaining of hypertension. The propositus exhibited an unusually low level of BChE activity, whereas her younger sister and her daughter had intermediate levels of BChE activity and her elder sister a normal level. Immunologically, the amount of BChE protein in the serum of the propositus was normal. DNA sequence analysis of the propositus identified a point mutation at codon 199 (GCA→GTA), resulting in a Ala→Val substitution. This alteration is one downstream codon from the catalytic active site (Ser, 198). A family study showed her younger sister and her daughter to have the same mutation.

Fat Intake and Clofibrate Administration Have Interrelated Effects on Liver Cholesterol Concentration and Serum Butyryl Cholinesterase Activity in Rats

Rats were fed for 15 d purified diets with different amounts of coconut fat, and with or without clofibrate. Fat was added at the expense of an isoenergetic amount of glucose. The hypolipidemic action of clofibrate was not influenced by the amount of fat in the diet. Clofibrate did not affect liver cholesterol concentration in rats fed the low fat diet, but it counteracted the rise in liver cholesterol seen in rats fed the high fat diet. This could relate to the observed raised intestinal clofibrate-hydrolyzing activity of rats fed the high fat diet, because hydrolysis of clofibrate gives rise to its biologically active form. In rats fed the low fat diet, but not in those fed the high fat diet, clofibrate raised the activity of serum esterase-1, which (unlike esterase-2) does not hydrolyze clofibrate. Possibly, the dramatic stimulatory effect of fat feeding on serum esterase-1 activity had overruled any influence of clofibrate. Clofibrate elevated serum butyryl cholinesterase activity, with this effect being amplified by fat feeding. High levels of dietary fat in the absence of dietary clofibrate did not alter serum butyryl cholinesterase activity. Clofibrate did not change butyryl cholinesterase and esterase-1 activities in small intestine. The high fat diet caused slightly higher levels of butyryl cholinesterase activity in small intestine, but markedly raised intestinal esterase-1 activity. This study shows that certain effects of clofibrate and a high fat diet are interrelated.