Red blood cell acetylcholinesterase activity among healthy dwellers of an agrarian region in Sri Lanka: a descriptive cross-sectional study

Fluorometric and Colorimetric Biosensors for the Assay of Cholinesterase Inhibitors

Cholinesterases, specifically acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), play critical roles in neurotransmission and are key targets for inhibitors with therapeutic and toxicological significance. This review focuses on the development and application of fluorometric and colorimetric biosensors for the detection of cholinesterase inhibitors. These biosensors take advantage of the unique properties of AChE and BChE to provide sensitive and selective detection methods essential for environmental monitoring, food safety, and clinical diagnostics. Recent advances in assay techniques, including the use of gold nanoparticles, pseudoperoxidase nanomaterials, and innovative enzyme-substrate interactions, are highlighted. This review also discusses challenges and future directions for optimizing these biosensors for practical applications, emphasizing their potential to enhance public health and safety.

Stability of acetylcholinesterase (AChE) activity in blood: the effect of the preservative agent

Fluoride anions are believed to inhibit acetylcholinesterase activity, thus there is a possibility that the activity may be affected by blood sampling into vials containing sodium fluoride as an anticoagulant. The paper aims to draw attention to the effect of the anticoagulant used in blood collection tubes on acetylcholinesterase activity. A stability study was conducted for 176 days on blood samples collected into tubes containing sodium fluoride or sodium EDTA. An improved Ellman procedure, utilizing spectrophotometric determination at 436 nm, was employed in order to determine acetylcholinesterase activity. An immediate decrease in acetylcholinesterase activity was observed in blood samples containing sodium fluoride. A significant decrease was evident immediately after blood collection and on the first day, after which the activity stabilized at 84% of the initial value. Subsequently, the activity increased to a level comparable to the initial value. In samples collected with EDTA, acetylcholinesterase activity was comparable to that in the sample without anticoagulant, and the activity remained constant for about 2 months. In conclusion, it is recommended that acetylcholinesterase activity be tested immediately after blood collection to reduce enzyme inhibition by fluoride anions, or that tubes with another anticoagulant, such as EDTA, be used.

An exploratory study; the gap between real reference interval and currently used reference interval of RBC AChE activities in South Korea

The current reference interval (RI) FOR red blood cell acetylcholinesterase (RBC AChE) activity in South Korea was established with data obtained from populations outside the country. The aim of this study was to assess the transferability of current RI of RBC AChE activity for organophosphate (OP) poisoning and determine the biological characteristics, real RI, and interindividual variation in RBC AChE activity in South Korea. Data were retrospectively collected for RBC AChE activity as measured by the modified Ellman's method for 782 patients who presented to our hospital. The clinical course did not differ significantly with the degree of deviation of RBC AChE activity from the currently used RI in 195 patients exposed to OP. RBC AChE activity was associated with gender and smoking status but not age or body mass index (BMI); however, a regression model incorporating age, gender, smoking status and BMI explained only a small portion of the variance in RBC AChE activity in South Korea. The RI of RBC AChE activity was 9,403-16,825 U/L, with 13.9% interindividual variation. The range of RBC AChE activity in South Korea is wider than RI currently used in clinical practice and exhibited a high degree of interindividual variation. In the absence of collecting pre-exposure values, it is recommended to conduct serial measurements, rather than one-point measurements, of RBC AChE activity as evidenced by the RI in OP poisoning.

Selected Liver Markers in Predicting the Severity of Organophosphate and Carbamate Poisoning

Background

Intentional ingestion of organophosphate (OP) and carbamate is a significant health issue worldwide. It causes adverse health effects on the liver. This study aimed to determine liver transaminases (AST and ALT) and bilirubin levels to assess the severity of poisoning in patients with acute OP and carbamate poisoning.

Methods

A descriptive cross-sectional study was conducted on patients admitted to a selected hospital in Sri Lanka with acute OP and carbamate poisoning. The severity of poisoning was measured by RBC cholinesterase and Peradeniya Organophosphorus Poisoning scale (POP), where six clinical features were assessed based on a 3-point scale. A score of 0–3 was considered mild, 4–7 to be moderate, and 8–11 to be severe poisoning. Liver parameters such as AST, ALT, and total and direct bilirubin were measured.

Results

Among the 188 screened patients, 166 were recruited. Majority were males (112, 67.5%). Kruskal–Wallis test showed significant differences in AST and ALT on admission and AST on discharge, across POP groups ((χ² (2, n = 166) = 26.48, p ≤ 0.001), (χ² (2, n = 166) = 14.31, p=0.001), and (χ² (2, n = 157) = 11.34, p=0.003), respectively)). Mann–Whitney U test showed significantly higher AST and ALT in the moderate POP group compared to the mild POP group (AST: U = 1709, z = −4.50, p ≤ 0.001, r = 0.36; ALT: U = 2114, z = −3.04, p=0.002, r = 0.26) on admission. In addition, the treatment outcomes (duration of hospital stay and duration of ventilator assistance) were significantly correlated (p ≤ 0.001) with the severity of poisoning and serum AST and ALT at the time of admission.

Conclusion

AST and ALT levels on admission and AST level at discharge showed significant correlations with the severity of poisoning. Treatment outcomes significantly correlated with the severity of poisoning and serum AST and ALT levels.

Efficacy of fresh frozen plasma transfusion in comparison with conventional regimen in organophosphate poisoning treatment: a meta-analysis study

OBJECTIVE

To evaluating the efficacy of fresh frozen plasma (FFP) in comparison with conventional regimen in the treatment of organophosphate (OP) poisoning.

METHODS

PubMed, ScopeMed, Cochrane, Scopus, and Google Scholar databases were searched. The search strategy used the following key words "organophosphate" and "poisoning or toxicity", "(atropine and oxime)", "fresh frozen plasma", "clinical trial", "outcome". The treatment with atropine or/and oxime was considered conventional therapy. The length of hospitalization, the length of ICU admission, need for mechanical ventilation and its duration, clinical recovery point, choline esterase level, mortality rate, and intermediate syndrome (IMS) occurrence were the key outcomes of interest. Databases were searched during the period of 2003-2019. Five studies were included in the analysis.

RESULTS

Pooling of data showed that the relative risk (RR) of mortality in OP poisoning for five included trials comparing FFP-treated group with conventional regimen therapy was [0.563 (95% CI (0.252, 1.255)]. The summary of RR for IMS in two studies was [RR: 1.34, 95% CI (0.655, 2.742)]. In addition, there was a non-significant mean difference (MD) in hospital stay [MD: -0.106, 95% CI (-0.434, 0.223)] in three included trials. A significant MD was observed in the length of ICU admission in two trials between FFP-treated group compared to the conventional treatment group [MD: -2.672, 95% CI (-4.189, -1.154)], but after random effects meta-analysis, the changes were not significant [MD: -2.015, 95% CI (-6.308, 2.277)]. The summary of fixed-effect meta-analysis for choline esterase level in three trails was [MD: -0.117, 95% CI (-0.468, 0.234)]. The RR of ventilation requirement for two included trials in the FFP-treated group comparing to the conventional regimen therapy was [0.84, 95% CI (0.691, 1.022)] while for ventilation duration in two studies was [MD: -0.183, 95% CI (-0.567, 0.201)].

CONCLUSION

The addition of FFP to conventional therapy did not improve the outcomes of mortality, IMS, hospital length of stay, cholinesterase levels, need or duration of mechanical ventilation, and only the length of ICU stay could affect in the treated group.

Biomonitoring of Acetylcholinesterase (AChE) Activity among Smallholder Horticultural Farmers Occupationally Exposed to Mixtures of Pesticides in Tanzania

Biomonitoring of pesticides exposure has currently become a matter of great public concern due to the potential health effects of pesticides. This study assessed levels of acetylcholinesterase (AChE) inhibition and associated health effects in uncontrolled smallholder farming systems in rural Tanzania. A cross-sectional study was conducted of 90 exposed farmers and 61 nonexposed controls from horticultural zones. A structured questionnaire was administered, and a capillary blood sample of 10 μl was used to measure AChE activity using an Erythrocyte Acetylcholinesterase Test Mate Photometric Analyzer kit (Model 400). A multiple logistic regression model was used to investigate determinants of pesticide exposure. The study revealed that smallholder farmers are occupationally exposed to pesticides. Exposed farmers had significantly lower AChE levels. The use of personal protective equipment (PPE) did not significantly reduce the likelihood of AChE inhibition. Women, younger and older farmers, and underweight, overweight, and obese farmers were at increased risk of AChE inhibition. Increase in age (10 years) increased likelihood of AChE inhibition by 6.7%, while decrease in BMI increased likelihood of AChE inhibition by 86.7% while increased pesticides contact hours increased risk of having lower AChE at about 3 times. The number of exposure symptoms (14.10 ± 7.70) was higher in exposed farmers than unexposed. Self-reported symptoms are confirmed to correlate to lower AChE. Prevalence of tiredness (71.6% against 15.5%), fatigue (64.8% against 27.6%), soreness in joints (59.1% against 20.7%), thirst (52.3% against 12.1%), skin irritation (52.1% against 17.2%), salivation and abdominal pain (50% against 8.6% and 31.0%, respectively), muscle weakness (47.7% against 24.1%), and memory loss (47.7% against and 29.3%) differed significantly between exposed and control. This study provides useful information regarding the level of occupational and environmental exposure to pesticides in smallholder horticultural production systems. Pesticides use needs to be controlled at farm level by developing pesticides monitoring and surveillance systems.