Influence of obstructive sleep apnea on serum butyrylcholinesterase activity and ischemia-modified albumin levels

OBJECTIVE: To investigate the effect of obstructive sleep apnea and continuous positive airway pressure treatment on serum butyrylcholinesterase activity and ischemia-modified albumin levels. METHODS: Thirty-two patients with obstructive sleep apnea and 30 age- and sex-matched controls were enrolled and underwent a diagnostic polysomnogram. The serum butyrylcholinesterase activity, ischemia-modified albumin levels, metabolic parameters, and polysomnography scores were detected and evaluated. Nine patients were studied before and after treatment with continuous positive airway pressure. RESULTS: The serum ischemia-modified albumin levels were significantly higher and the butyrylcholinesterase activity was significantly lower in patients with obstructive sleep apnea than in the controls (p<0.001). The continuous positive airway pressure treatment decreased the modified albumin levels and elevated the buthrylcholinesterase activity (p = 0.019 and p = 0.023, respectively). The modified albumin levels were positively correlated with the apnea-hypopnea index (r = 0.462, p = 0.008) at baseline. Elevated ischemia-modified albumin levels can be more accurate than butyrylcholinesterase activity at reflecting the presence of obstructive sleep apnea. Receiver operating characteristic curves revealed a significant difference between the areas under the curve 0.916 for ischemia-modified albumin and 0.777 for butyrylcholinesterase (z = 2.154, p = 0.031). CONCLUSION: The elevated ischemia-modified albumin level was significantly associated with obstructive sleep apnea and was more sensitive than butyrylcholinesterase activity in reflecting obstructive sleep apnea. The continuous positive airway pressure treatment helped to ameliorate the imbalance. .

Influence of Toxoplasma gondii Acute Infection on Cholinesterase Activities of Wistar Rats

Several studies have shown the mechanisms and importance of immune responses against Toxoplasma gondii infection and the notable role of cholinesterases in inflammatory reactions. However, the association between those factors has not yet been investigated. Therefore, the aim of this study was to evaluate the acetylcholinesterase (AChE) activity in blood and lymphocytes and the activity of butyrylcholinesterase (BChE) in serum of rats experimentally infected with T. gondii during the acute phase of infection. For that, an in vivo study was performed with evaluations of AChE and BChE activities on days 5 and 10 post-infection (PI). The activity of AChE in blood was increased on day 5 PI, while in lymphocytes its activity was enhanced on days 5 and 10 PI (P<0.05). No significant difference was observed between groups regarding to the activity of BChE in serum. A positive (P<0.01) correlation was observed between AChE activity and number of lymphocytes. The role of AChE as an inflammatory marker is well known in different pathologies; thus, our results lead to the hypothesis that AChE has an important role in modulation of early immune responses against T. gondii infection.

Butyrylcholinesterase and diabetes mellitus in the CHE2 C5- and CHE2 C5+ phenotypes / Butirilcolinesterase e diabetes melito nos fenótipos CHE2 C5- e CHE2 C5+

OBJECTIVE:To investigate the relationship between butyrylcholinesterase (BChE) activities (total and band specific) and diabetes mellitus. SUBJECTS AND METHODS: BChE activities (BChEA, AC 4/5, AC OF and RC5) were analyzed in 101 type 1 (DM1) and in 145 type 2 (DM2) diabetic patients, in relation to phenotype, weight and incidence of metabolic syndrome (MS) in these patients. The C4/5 and C5 complex were separated from other molecular forms (C OF) using an acid agar gel. RESULTS: The BChE activity (BChEA) and the absolute activities of C4/5 (AC4/5) and C OF (AC OF) showed a high positive correlation coefficient to weight in the CHE2 C5- group, while the relative activity of C5 complex (RC5) showed a negative correlation to weight. CONCLUSIONS: The present study suggests that the positive correlation of the BChE activities to diabetes mellitus and to insulin resistance may depend on the CHE2 locus variability. High values of BChE activities were associated with insulin resistance only in CHE2 C5- diabetic patients, while in CHE2 C5+ diabetic patients, the presence of C5 complex, especially in a relatively high proportion, leads to less fat storage and better protection against metabolic syndrome.

OBJETIVO: Investigar a associação entre as atividades (total e banda específica) da butirilcolinesterase (BChE) e diabetes melito. SUJEITOS E MÉTODOS: As atividades da BChE (BChEA, AC4/5, AC OF e RC5) foram analisadas em 101 pacientes diabéticos do tipo 1 (DM1) e 145 do tipo 2 (DM2) em relação aos fenótipos, ao peso e à incidência da síndrome metabólica. Os complexos C4/5 e C5 foram separados das outras formas moleculares (C OF), usando gel de ágar ácido. RESULTADOS: A atividade da BChE (BChEA) e as atividades absolutas de C4/5 (AC4/5) e de C OF (AC OF) mostraram altos coeficientes de correlações positivos com peso no grupo de CHE2 C5-, enquanto a atividade relativa do complexo C5 (RC5) mostrou correlação negativa com o peso. CONCLUSÕES: O presente estudo sugere que as correlações positivas das atividades da BChE com diabetes melito e com a resistência à insulina podem depender da variabilidade do loco CHE2. Altos valores nas atividades da BChE estão associados com a resistência à insulina somente nos pacientes diabéticos CHE2 C5-, enquanto nos pacientes diabéticos CHE2 C5+ a presença do complexo C5, especialmente em alta proporção relativa, leva a um menor estoque de gordura e à maior proteção contra a síndrome metabólica.

Biochemical markers in blood can predict the cirrhotic evolution of chronic hepatitis

Approximately one-fifth of chronically infected patients develop significant chronic liver inflammation that progressively can lead to cirrhosis and HCC. The course and outcome of chronic liver disease may be difficult to predict. There is an urgent need to develop and validate noninvasive tests that can accurately reflect the full spectrum of hepatic inflammation and fibrosis. Serum fibronectin can differentiate HCV infected patients with liver fibrosis from patients with non fibrosis. Serum pseudocholinesterase activity might be a more specific indicator of liver dysfunction than the traditional liver function tests while prothrombin time is a measurement of synthetic liver function. To study the ability of three serum biochemical markers when combined in specific equation can differentiate between chronic active hepatitis and cirrhotic patients. Patients were 29 with chronic active hepatitis [CAR] and 28 with liver cirrhosis. These were compared with 10 healthy controls. Liver function tests were done to all subjects. Three biochemical parameters were also measured and combined in a certain equation. Fibronectin was measured using ELISA, pseudocholinesterase using colorimetric method while prothrombin activity was done using calcium thromboplastin. It was found that the equation significantly discriminated between fibrosis and cirrhosis at cut off value of 243.28, with sensitivity 100% and specificity 60% and area under the curve 80%, p=0.000. The three biochemical inexpensive parameters when combined can contribute to the differentiation between liver cirrhosis and chronic hepatitis

Molecular forms of butyrylcholinesterase and obesity

This study compared obese (N = 134) and unobese (N = 92) male blood donors, regarding the relative intensity (RI) and activity of different molecular forms (G1, G2, G4 and G1-ALB) of butyrylcholinesterase (BChE, EC 3.1.1.8) found in plasma, thereby searching for an association between these variables with obesity and SNPs of exons 1 and 4 of the BCHE gene. It was shown that obese and unobese individuals do not differ in the RI of each BChE band, even when classifying the sample into three genotypes of exons 1 and 4 of the BCHE gene (-116GG/539AA, -116GG/539AT, -116GA/539AT). Although the mean BChE activity of each band was significantly higher in obese than in unobese blood donors, the proportions of BChE bands were maintained, even under the metabolic stress associated to obesity, thereby leading to infer that this proportion is somehow regulated, and may therefore be important for BChE functions.

Prognostic and diagnostic value of serum pseudocholinesterase, serum aspartate transaminase, and serum alinine transaminase in malignancies treated by radiotherapy.

BACKGROUND: There is substantial evidence that environmental factors cause or accelerate the onset of malignancy. Environmental factors, due to the presence of many pollutants and carcinogenic agents, alter cellular growth, which leads to biochemical changes in the blood. MATERIALS AND METHODS: In the present study, we estimated serum pseudocholinesterase (PCHE), serum aspartate transaminase (AST), and serum alanine transaminase (ALT) in 92 patients with head and neck cancer and 71 patients with cancer of the uterine cervix; all of them were patients attending our department for radiation therapy. We also estimated PCHE, AST, and ALT levels in 30 healthy normal individuals. The estimations in cancer patients were done before the start of radiotherapy, midway through radiotherapy (30 Gy dose), at the end of radiotherapy, and during subsequent monthly follow-up visits over a period of at least 6 months. RESULTS AND DISCUSSION: We have observed that the PCHE levels were lower (31-49% of normal value) in all patients with malignancies, except in those with stage II head and neck cancers. We also found that the levels start increasing as radiotherapy progresses. The patients with no detectable/visible disease activity at 6 months follow-up showed PCHE values in the normal range. Similarly, the AST and ALT values were much higher (138-229% of normal value) in all the malignant cases as compared to the normal healthy individuals. The values decrease and approach normal levels as radiotherapy progresses and, in 92% of head and neck cancer cases [stages IIA, IIB, and IIIA] with no disease activity, the PCHE, AST, and ALT were normal or near normal; the corresponding figure in cancer cervix cases was 89%. From the present study we conclude that PCHE, AST, and ALT can be used as good prognostic biochemical tumor markers in the management of malignancies of the head and neck and uterine cervix.

Evaluation of pesticides induced toxicity by oxidative stress and inflammatory biomarkers

To evaluate pesticides induced toxicity by oxidative stress and inflammatory biomarkers among tobacco farmers in district Sawabi of Pakistan. Cross sectional descriptive study. Place and Duration of Study: The study was conducted in district Sawabi, NWFP, Pakistan from Jan 2006 to March 2008. Total of 109 adult male consisting of 55 tobacco farmers and 54 unexposed subjects were included from district Sawabi, NWFP, Pakistan. Plasma Butyrylcholinesterase [BChE] and Gamma Glutamyltransferase [GGT] were measured on Vita Lab Selectra E. Plasma Malondialdyhyde [MDA] and Nitric oxides [NO] were estimated by formation of thiobarbituric acid and the Griess reaction respectively. Serum C-reactive protein [CRP] was assayed on Immulite-1000. The tobacco farmers age ranged from 16-72 years. Plasma BChE mean [SD] levels were significantly decreased to 5596 [929] as compared to 6821 [1365] U/L in the pesticides exposed farmers [P<0.001]. Oxidative stress and inflammatory markers in the pesticides exposed farmers were significantly raised as compared to control which are given as mean [SD] [a] GGT 24[6] vs 17[4] U/L [b] Nitrate 34.27[19.71] vs 21.35 [11.57] umol/L [c] CRP 1.44 [0.860] vs 0.911[0.538] mg/L and MDA 4.71 [2.01] vs 3.27 [0.94] nmol/ng [P<0.001] respectively. The plasma BChE levels showed a significant inverse correlation with plasma MDA [r=-0.39], nitrate [r=-0.44] and CRP[r=-0.40]. Apart from plasma BChE inhibition, pesticide exposure enhanced oxidative stress and inflammatory markers in the tobacco farmers. Plasma BChE has inverse correlation with lipid peroxidation, nitrate production and inflammatory biomarkers which might be used for monitoring of pesticides induced risks in occupational workers

Correlación y conversión entre los valores de actividad de la colinesterasa plasmática medida por tres técnicas diferentes / Correlation and conversion of plasma cholinesterase activity values using three techniques

OBJETIVO: Determinar las relaciones matemáticas entre tres técnicas cuantitativas empleadas para medir la actividad de la colinesterasa plasmática, a partir de los valores de referencia ya establecidos para dos poblaciones de Antioquia, Colombia. MÉTODOS:Diseño descriptivo, transversal y prospectivo. Se conformaron dos muestras independientes representativas de la población laboral adulta (18-65 años), no expuesta a plaguicidas inhibidores de la colinesterasa y vinculada al Seguro Social, del valle de Aburrá (415 personas) y del cercano oriente antioqueño (412 personas), del departamento de Antioquia, Colombia. La colinesterasa plasmática (EC 3.1.1.8) se midió mediante tres técnicas cuantitativas: Michel, EQM® y Monotest®. Se elaboraron ecuaciones de regresión que relacionaran entre sí los resultados de las tres técnicas estudiadas. RESULTADOS: Se definieron seis ecuaciones de regresión lineal simple que permitieron relacionar los resultados de las tres técnicas de medición de colinesterasa plasmática analizadas. La correlación entre las técnicas fue moderada (r: de 0,686 a 0,771), pero aumentó (r: de 0,744 a 0,811) al eliminar 12 (1,5 por ciento) valores extremos. Las asociaciones entre las técnicas fueron altamente significativas (P < 0,001). Las ecuaciones Y = a + bX ajustadas son: EQM (U/mL) = 0,40773 + 1,8757 (Michel [delta pH/hora]); Michel (delta pH/hora) = 0,25799 + 0,33871 (EQM [U/mL]); Monotest (U/L) = 462,0 + 4 565,0 (Michel [delta pH/hora]); Michel (delta pH/hora) = 0,42956 + 0,00012125 (Monotest [U/L]); EQM (U/mL) = 0,75333 + 0,00031056 (Monotest [U/L]); y Monotest (U/L) = 262,0 + 2 118,0 (EQM [U/mL]). CONCLUSIONES: Los modelos propuestos permiten convertir los valores de actividad de la colinesterasa medida con las tres técnicas estudiadas.

OBJECTIVES: To determine mathematical correlations of three quantitative techniques to measure plasma cholinesterase, using reference values already established for two populations in the department of Antioquia, Colombia. METHODS: In this descriptive, cross-sectional, prospective study, two independent, representative samples of working adults (18 to 65 years old) were examined. In both samples the adults worked for businesses associated with ColombiaÆs Social Security system. Adults in the two samples had not been exposed to cholinesterase-inhibiting pesticides. The samples were from two neighboring regions of the department of Antioquia: one sample (415 adults) was from the Aburrá Valley, and the other (412 adults) was from Oriente Antioqueño (Eastern Antioquia). Plasma cholinesterase (EC 3.1.1.8) was measured using three quantitative methods: Michel, EQM, and Monotest. Linear regression equations were developed to correlate results of these three techniques. RESULTS: Six simple linear regression equations were defined to show the relationship of three measurement techniques for plasma cholinesterase. There was a moderate correlation of the three techniques (r = 0.686 to 0.771), but it increased (r = 0.744 to 0.811) when 12 (1.5 percent) outliers were eliminated. Associations among the three techniques were highly significant (P < 0.001). The adjusted equations for Y = a + bX are: EQM (U/mL) = 0.40773 + 1.8757 (Michel [delta pH/h]); Michel (delta pH/h) = 0.25799 + 0.33871 (EQM [U/mL]); Monotest (U/L) = 462.0 + 4 565.0 (Michel [delta pH/h]); Michel (delta pH/h) = 0.42956 + 0.00012125 (Monotest [U/L]); EQM (U/mL) = 0.75333 + 0.00031056 (Monotest [U/L]); and Monotest (U/L) = 262.0 + 2 118.0 (EQM [U/mL]). CONCLUSIONS: The proposed mathematical models allow conversion of cholinesterase activity values using the Michel, EQM, and Monotest techniques. These models can be of assistance in Colombia and other countries where a variety of measurement techniques are used, and where it becomes difficult to compare the results of different studies. Having mathematical models available for conversion of established values can be beneficial whether for clinical or epidemiological purposes.

Biochemical and clinical profile after organophosphorus poisoning--a placebo-controlled trial using pralidoxime.

BACKGROUND: Organophosphorus (OP) compounds are the most common suicidal poison in developing countries and mortality continues to be high. METHODS: A study was done to see butyryl cholinesterase (BuChE) profile after OP poisoning in pralidoxime (P2AM) and placebo treated cases. Highest recommended dose of P2AM was used to study the reactivation of cholinesterase. Clinical outcomes like, correlation of BuChE and severity of poisoning, mortality and complications like Type I and II paralysis, need for ventilation and ICU stay were also studied. RESULTS: Twenty one cases of moderate and severe poisoning with OP compounds were included in the study. Mean BuChE levels came up gradually over 6-7 days, some taking up to two weeks. There was no. difference between the treatment and placebo groups. BuChE levels did not correlate with severity of poisoning nor did it correlate with Type I or II paralysis, need for ventilation, ICU stay or mortality. CONCLUSIONS: Treatment with P2AM does not make any difference in BuChE reactivation or complications of moderate and severe OP poisoning. We have not been using P2AM for OP poisoning in our medical ICU with good patient outcomes.

Oxidative damage in intermediate syndrome of acute organophosphorous poisoning.

BACKGROUND & OBJECTIVES: The main cause of morbidity due to organophosphate poisoning is intermediate syndrome (Type II paralysis) that can occur 48-72 h after poisoning. Mechanisms that underlie the intermediate syndrome are not known. This study investigates the role of oxidative damage to muscles as a possible mechanism underlying the development of the intermediate syndrome. METHODS: Nineteen patients with acute organophosphate poisoning were evaluated from admission to discharge from intensive care for the severity of poisoning and the development and duration of the intermediate syndrome. Blood cholinesterases and parameters of oxidative stress were studied daily and their temporal profiles analysed according to the severity of poisoning and the development and duration of the intermediate syndrome. RESULTS: Fifteen patients had severe poisoning and 16 developed intermediate syndrome. There was a positive association between the severity of poisoning and the occurrence of intermediate syndrome. There was no association between the organophosphate ingested and the development of intermediate syndrome. Erythrocyte membrane acetylcholinesterase and serum butyrylcholinesterase levels at admission and over the course of poisoning were significantly (P < 0.001) reduced in patients compared to controls. There were significantly (P < 0.05) higher levels of lipid peroxidation, conjugated dienes and protein thiols in erythrocyte membranes of patients who developed the intermediate syndrome compared to healthy controls, in patients who developed intermediate syndrome compared to those who did not and in patients with long compared to short duration intermediate syndrome. INTERPRETATION & CONCLUSION: In acute organophosphate poisoning, severe and prolonged acetylcholinesterase inhibition is associated with oxidative stress, detected in erythrocyte membranes, that occurs early in the course of poisoning and may contribute to the development and severity of intermediate syndrome.

Effects of mercury on the arterial blood pressure of anesthetized rats

The available data suggests that hypotension caused by Hg2+ administration may be produced by a reduction of cardiac contractility or by cholinergic mechanisms. The hemodynamic effects of an intravenous injection of HgCl2 (5 mg/kg) were studied in anesthetized rats (N = 12) by monitoring left and right ventricular (LV and RV) systolic and diastolic pressures for 120 min. After HgCl2 administration the LV systolic pressure decreased only after 40 min (99 +or - 3.3 to 85 + or - 8.8 mmHg at 80 min). However, RV systolic pressure increased, initially slowly but faster after 30 min (25 + or - 1.8 to 42 + or - 1.6 mmHg at 80 min). Both right and left diastolic pressures increased after HgCl2 treatment, suggesting the development of diastolic ventricular dysfunction. Since HgCl2 could be increasing pulmonary vascular resistance, isolated lungs (N = 10) were perfused for 80 min with Krebs solution (continuous flow of 10 ml/min) containing or not 5 µM HgCl2. A continuous increase in pulmonary vascular resistance was observed, suggesting the direct effect of Hg2+ on the pulmonary vessels (12 + or - 0.4 to 29 + or - 3.2 mmHg at 30 min). To examine the interactions of Hg2+ and changes in cholinergic activity we analyzed the effects of acetylcholine (Ach) on mean arterial blood pressure (ABP) in anesthetized rats (N = 9) before and after Hg2+ treatment (5 mg/kg). Using the same amount and route used to study the hemodynamic effects we also examined the effects of Hg2+ administration on heart and plasma cholinesterase activity (N = 10). The in vivo hypotensive response to Ach (0.035 to 10.5 µg) was reduced after Hg2+ treatment. Cholinesterase activity (µM h-1 mg protein-1) increased in heart and plasma (32 and 65 percent, respectively) after Hg2+ treatment. In conclusion, the reduction in ABP produced by Hg2+ is not dependent on a putative increase in cholinergic activity. HgCl2 mainly affects cardiac function. The increased pulmonary vascular resistance and cardiac failure due to diastolic dysfunction of both ventricles are factors that might contribute to the reduction of cardiac output and the fall in arterial pressure

Valores de referencia de poblaciones senecta y adulta de la ciudad de México: parámetros bioquímicos y hematológicos / Reference values for elderly and adult population of Mexico city: biochemical and hematological tests

El desarrollo de la Gereontología en México es incipiente, de ahí que no existan valores de referencia confiables de pruebas bioquímicas y hematológicas para la población senecta. Por tal motivo, se determinaron los valores de laboratorio de: biometría hemática y pruebas rutinarias bioquímicas, lípidos, electrolitos, proteínas totales, albúmina, bilirrubina total y conjugada, aspartato-aminotransferasa (AST), alanino-aminotransferasa (ALT), gama-glutamiltransferasa (GGT) y pseudocolinesterasa (CHS) séricos, en dos grupos de 400 individuos clínicamente sanos de ambos sexos y bajo nivel socioeconómico de la ciudad de México, uno de mayores de 60 años y otro de adultos entre 25 y 45 años. Se utilizaron métodos manuales estandarizados para realizar las pruebas. Los intervalos fueron determinados por el cálculo de la mediana y el percentil central 95 con la prueba de Tukey. Los resultados en la fórmula roja para los senectos muestran disminución en los límites inferiores de los intervalos, siendo estadísticamente significativo (p < 0,05) comparando con los adultos jóvenes. Para las pruebas bioquímicas, se encontraron valores altos estadísticamente significativos (p < 0,05) en ácido úrico, colestrol, cLDL y triglicéridos, y bajos en cHDL, proteínas totales, albúmina y fosfato. Se concluye que en la población senecta mexicana algunos analitos se ven afectados por la edad, a diferencia de lo reportado para la población anglosajona

Serum butyrylcholinesterase of non-human primate shows amine sensitive aryl acyl amidase and metallopeptidase activities and characteristics similar to those of the human serum enzyme.

Butyrylcholinesterase (BChE) was purified from monkey serum and the catalytic activities were examined. The enzyme has a molecular mass of approximately equal to 74 kDa as seen by SDS-gel electrophoresis. Monkey serum BChE also exhibits an amine sensitive aryl acylamidase (AAA) and a metallocarboxypeptidase activity. The tyramine activation of the aryl acylamidase activity and the metal chelator inhibition of the peptidase activity were characteristics similar to those of the human enzyme. Studies on 65Zn2+ binding and zinc chelate Sepharose chromatography showed that monkey serum BChE and human serum BChE have similar characteristics. Limited alpha chymotrypsin digestion of monkey serum BChE followed by Sephadex gel chromatography cleaved the enzyme into a 36 kDa fragment exhibiting peptidase activity. However the 20 kDa fragment corresponding to cholinesterase and aryl acylamidase activity was not detectable possibly due to the unstable nature of the fragment. Immunological studies showed that a polyclonal antibody against human serum BChE cross reacted with monkey serum BChE. The identical nature of the catalytic activities of human serum BChE and monkey serum BChE supports the postulate that all three catalytic activities co-exist in the same enzyme. This is the first time that purification and characterisation of the monkey serum BChE which has the highest sequence identity and immunological identity with that of human serum BChE, is being reported.

Variantes de butirilcolinesterasa sérica en población de Santiago oriente / Serum butyrylcholinesterase variants in eastern Santiago

Succinylcholine causes prolonged apneas in a proportion if subjects that have genetical defect of butyrylcholinesterase, due to the presence of unusual alleles in the locus BCHE. To estimate allele frequences of 3 variants of serum butyrylcholinesterase, BCHE*U, BCHE*A and BCHE*F in an urban population of Santiago, Chile, different phenotypes for the locus BCHE were determined in 300 blood samples coming from patients of a private clinical laboratory. The population was formed by an admixture of Amerindian and European (mostly spanich) people. The frequency of BCHE*A was similar to the expected for this population, but BCHE*F frequency was greater than predicted. Eight subjects had a genotype BCHE AK. The higher frequency found for BCHE*F is probably due to the use of more precise detection techniques. Although the used method cannot distinguish BCHE UK from BCHE UU, the findings of individuals with BCHE AK, must lead to the suspicion that the frequency of the allel BCHE K is not negligible in Santiago

Correlation of time course of blood cholinesterase activity and toxic manifestations of acute methylparathion in antidote treated rats.

Study was conducted to find out the correlation between red blood cholinesterase (RBC ChE) and plasma butyryl cholinesterase (BuChE) activities and toxic signs of oral methylparathion (MPT) and their recovery pattern with or without atropine treatment in female rats. Enzyme activity was estimated before and after an oral dose of MPT (7.5 mg/kg-1) at various time intervals upto 120 hr. Antidote groups received atropine (10 mg/kg-1, i.p.), either alone or with diazepam (2.5 mg/kg-1, i.p.), at the onset of toxic signs. Inhibition of enzyme activity served as definite index of acute toxicity of MPT. RBC ChE activity correlated with the intensity of toxic signs in no-antidote rats, while in atropine treated groups, there was no correlation. BuChE levels did not correlate with toxic signs in any of the groups except in the fatal group. The resynthesis of both the enzymes was complete in 120 hr study and did not synchronize with the recovery pattern of animals from toxic signs. Compared to BuChE, RBC ChE activity was found to be a more sensitive indicator for the diagnosis of severity of MPT toxicity.

Species variation in the specificity of cholinesterases in human and rat blood samples.

Acetylthiocholine iodide (ATC) as a common substrate in the combined assay of red blood cell cholinesterase (RBC ChE) and butyrylcholinesterase (BuChE) do not provide the accurate individual enzyme activities. Hence, in the present study the two enzyme activities in the same sample were assayed with the help of two different substrate, ATC and butyrylthiocholine iodide (BTC). Specificity of BTC towards BuCHE was found in blood, plasma and serum, while ATC is nonspecifically hydrolysed by both RBC ChE and BuChE. ATC gives significantly higher enzyme activity (P < 0.001) in rat plasma/serum and significantly lower enzyme activity (P < 0.0001; P < 0.001) in human plasma/serum. The possible reasons are discussed for substrate specity in various species in the assay of ChEs.

Improved colorimetric method for cholinesterase activity.

A modified colorimetric method for the estimation of cholinesterase activity has been worked out using two different substrates, acetylthiocholine iodide for total cholinesterase and a specific substrate, butyrylthiocholine iodide for pseudocholinesterase in the same sample. This is a modification of the method described by Voss and Sachsse (1970) wherein acetylthiocholine iodide was used for both total and pseudo cholinesterase activities. The pseudocholinesterase obtained with acetylthiocholine iodide was significantly higher (P < 0.0001) than that with butyrylthiocholine iodide either in whole blood or serum samples. Acetylthiocholine iodide while reacting with pseudocholinesterase in serum or plasma samples might also be interacting with the small quantities of acetylcholinesterase present. It is therefore suggested that butyrylthiocholine iodide and acetylthiocholine iodide may be used to determine pseudocholinesterase and total cholinesterase activities respectively. The use of two substrates with a few more alterations in the experimental conditions increased the validity of this simple and rapid colorimetric method.

Erythrocyte and plasma cholinesterase activity in normal pregnancy.

Erythrocyte acetylcholinesterase and plasma cholinesterase was estimated in 50 normal pregnant women and 22 age matched normal non-pregnant women. Plasma cholinesterase was significantly decreased while erythrocyte cholinesterase was significantly increased during pregnancy. These changes may be related to altered haemodynamics and or other inter-related changes occurring in pregnancy.

Effect of GABA, muscimol and picrotoxin given in third ventricle on serum cholinesterases and monoamine oxidase and on plasma succinic dehydrogenase in rats.

Effect of injection in third ventricle of GABA, the GABA agonist muscimol, and the GABA antagonist picrotoxin on the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and monoamine oxidase (MAO) in serum and succinic dehydrogenase (SDH) in plasma has been studied. Surprisingly, the AChE, BuChE, MAO and SDH enzymes activity were inhibited by GABA and muscimol, while they were enhanced by picrotoxin.