Reduced pseudocholinesterase activity in patients with HELLP syndrome

Optical imaging probes for selective detection of butyrylcholinesterase

Butyrylcholinesterase (BChE), a member of the human serine hydrolase family, is an essential enzyme for cholinergic neurotransmission as it catalyzes the hydrolysis of acetylcholine. It also plays central roles in apoptosis, lipid metabolism, and xenobiotic detoxification. On the other side, abnormal levels of BChE are directly associated with the formation of pathogenic states such as neurodegenerative diseases, psychiatric and cardiovascular disorders, liver damage, diabetes, and cancer. Thus, selective and sensitive detection of BChE level in living organisms is highly crucial and is of great importance to further understand the roles of BChE in both physiological and pathological processes. However, it is a very complicated task due to the potential interference of acetylcholinesterase (AChE), the other human cholinesterase, as these two enzymes share a very similar substrate scope. To this end, optical imaging probes have attracted immense attention in recent years as they have modular structures, which can be tuned precisely to satisfy high selectivity toward BChE, and at the same time they offer real time and nondestructive imaging opportunities with a high spatial and temporal resolution. Here, we summarize BChE selective imaging probes by discussing the critical milestones achieved during the development process of these molecular sensors over the years. We put a special emphasis on design principles and biological applications of highly promising new generation activity-based probes. We also give a comprehensive outlook for the future of BChE-responsive probes and highlight the ongoing challenges. This collection marks the first review article on BChE-responsive imaging agents.

Association of Reduced Maternal Plasma Cholinesterase Activity With Preeclampsia: A Meta-Analysis

Blood butyrylcholinesterase (BChE) activity has been found to decrease during pregnancy and reportedly decrease even more in preeclampsia (PE). The purpose of the present meta-analysis was to answer a specific question of whether BChE activity (in the plasma, serum, or whole blood) is reduced in pregnant women suffering from PE compared to those with normal pregnancy. The meta-analysis included 15 studies with 20 records of BChE activity in 608 women compared to 569 healthy pregnant (control) ones. The studies were subjected to quality assessment using the Newcastle-Ottawa Scale (NOS). Using the Meta-Essentials software program 1.5, the one-group random effects model and forest plot revealed that the percentage of BChE activity in pregnant women with PE was 84.84% of the control value, with a standard error of 4.09 and 95% C.I. of 76.28, 93.41, indicating a significant 15.16% reduction in BChE activity in comparison to healthy pregnancy. No significant heterogeneity was seen in the analyzed data and the funnel plot did show publication bias. Subgroup (mild, severe, and unclassified PE) forest plot analysis revealed that the % BChE activities in PE compared to respective healthy pregnancies were 96.28%, 97.08%, and 76.62%, respectively with no heterogeneity. The median NOS score of the 15 studies included in the meta-analysis was 7, ranging from 5 to 8 (medium to high quality), and the forest plot showed an effect size of 0.735. This meta-analysis shows that BChE activity is reduced in PE compared with normal pregnancy and its value as a biomarker warrants further clinical studies.

Pharmacokinetics a>nd Tolerability of Intraperitoneal Chloroprocaine After Fetal Extraction in Women Undergoing Cesarean Delivery

BACKGROUND

Intraperitoneal chloroprocaine has been used during cesarean delivery to supplement suboptimal neuraxial anesthesia for decades. The short in vitro half-life of chloroprocaine (11-21 seconds) has been cited to support the safety of this approach. However, there are no data regarding the rate of absorption, representing patient drug exposure, through this route of administration. Accordingly, we designed a study to determine the in vivo half-life of intraperitoneal chloroprocaine and assess clinical tolerability.

METHODS

We designed a single-center, prospective, cohort, multiple-dose escalation study of women 18 to 50 years of age undergoing cesarean delivery with spinal anesthesia. Chloroprocaine (40 mL) was administered after delivery of the newborn and before uterine closure. The first cohort (n = 5) received 1%, the second cohort (n = 5) received 2%, and the third cohort (n = 5) received 3% chloroprocaine solution. Maternal blood samples were obtained before administration and 1, 5, 10, 20, and 30 minutes after dosing. The primary objective was to define the pharmacokinetic profile of intraperitoneal chloroprocaine, including in vivo half-life. The secondary objective was to evaluate tolerability through determination of peak plasma concentration and prospective assessment for local anesthetic systemic toxicity.

RESULTS

The peak plasma concentration occurred 5 minutes after intraperitoneal administration in all 3 cohorts: 64.8 ng/mL (6.5 µg/kg), 28.7 ng/mL (2.9 µg/kg), and 799.2 ng/mL (79.9 µg/kg) for 1%, 2%, and 3% chloroprocaine, respectively. The in vivo half-life of chloroprocaine after intraperitoneal administration was estimated to be 5.3 minutes (95% confidence interval, 4.0-6.6). We did not detect clinical signs of local anesthetic systemic toxicity in any of the 3 cohorts.

CONCLUSIONS

The in vivo half-life of intraperitoneal chloroprocaine (5.3 minutes) is more than an order of magnitude greater than the in vitro half-life (11-21 seconds). However, maximum plasma concentrations of chloroprocaine (Cmax range, 0.05-79.9 µg/kg) were not associated with local anesthetic systemic toxicity and remain well below our predefined safe level of exposure (970 µg/kg) and levels associated with clinical symptoms (2.6-2.9 mg/kg). Therefore, our study suggests that intraperitoneal chloroprocaine, in a dosage ≤1200 mg, administered after fetal extraction, is well tolerated during cesarean delivery.

Extreme variability in succinylcholine dose for muscle relaxation in electroconvulsive therapy

OBJECTIVES

To determine what dose of succinylcholine falls outside the range of 2 SD above or below the mean optimal dose of 0.9 mg/kg used for electroconvulsive therapy (ECT).

METHODS

In this retrospective chart review, for all patients who received ECT at our institution within the 5-year study period, the initial dose of succinylcholine in milligrams per kilogram was compared with subsequent doses after adjustments were made for individual patient responses. Mean and SD were calculated using the dose of succinylcholine, once the optimal dose for each patient had been determined, based on clinical response.

RESULTS

Five hundred patients treated during the 5-year period met inclusion criteria, 180 (36%) of whom required an adjustment of the succinylcholine dosing either above (119 patients) or below (61 patients) the 0.9 mg/kg standard after their first treatment.

CONCLUSIONS

In those patients who required an adjustment of 2 SD either above or below the mean dose of succinylcholine (29 patients, 5.8%), adequate neuromuscular blockade was only achieved with either an increased dose of up to 2.10 mg/kg or a decreased dose as low as 0.29 mg/kg.

Reversal of succinylcholine induced apnea with an organophosphate scavenging recombinant butyrylcholinesterase

BACKGROUND

Concerns about the safety of paralytics such as succinylcholine to facilitate endotracheal intubation limit their use in prehospital and emergency department settings. The ability to rapidly reverse paralysis and restore respiratory drive would increase the safety margin of an agent, thus permitting the pursuit of alternative intubation strategies. In particular, patients who carry genetic or acquired deficiency of butyrylcholinesterase, the serum enzyme responsible for succinylcholine hydrolysis, are susceptible to succinylcholine-induced apnea, which manifests as paralysis, lasting hours beyond the normally brief half-life of succinylcholine. We hypothesized that intravenous administration of plant-derived recombinant BChE, which also prevents mortality in nerve agent poisoning, would rapidly reverse the effects of succinylcholine.

METHODS

Recombinant butyrylcholinesterase was produced in transgenic plants and purified. Further analysis involved murine and guinea pig models of succinylcholine toxicity. Animals were treated with lethal and sublethal doses of succinylcholine followed by administration of butyrylcholinesterase or vehicle. In both animal models vital signs and overall survival at specified intervals post succinylcholine administration were assessed.

RESULTS

Purified plant-derived recombinant human butyrylcholinesterase can hydrolyze succinylcholine in vitro. Challenge of mice with an LD100 of succinylcholine followed by BChE administration resulted in complete prevention of respiratory inhibition and concomitant mortality. Furthermore, experiments in symptomatic guinea pigs demonstrated extremely rapid succinylcholine detoxification with complete amelioration of symptoms and no apparent complications.

CONCLUSIONS

Recombinant plant-derived butyrylcholinesterase was capable of counteracting and reversing apnea in two complementary models of lethal succinylcholine toxicity, completely preventing mortality. This study of a protein antidote validates the feasibility of protection and treatment of overdose from succinylcholine as well as other biologically active butyrylcholinesterase substrates.

Butyrylcholinesterase as a prognostic marker: a review of the literature

BACKGROUND

Butyrylcholinesterase (BChE) is an α-glycoprotein synthesized in the liver. Its serum level decreases in many clinical conditions such as acute and chronic liver damage, inflammation, injury and infections, and malnutrition.

METHODS AND RESULTS

This review collects the main evidence on the emerging role of butyrylcholinesterase as a prognostic marker of liver and nonliver diseases as well as a marker of protein-energy malnutrition and obesity. In fact, serum concentrations and BChE activity seem to accurately reflect the availability of amino acidic substrates and/or derangement in protein synthesis due to hepatocellular damage. In cancer, with or without liver impairment, serum BChE levels serve as an accurate functional and prognostic indicator, useful for monitoring clinical and therapeutic interventions according to patients' prognosis. In the absence of inflammation, BChE could also serve as an index of the effectiveness of nutritional support.

CONCLUSIONS

Serum BChE assessment should be included in routine clinical diagnostic procedures to evaluate patient clinical conditions, in particular in cases of inflammation and/or protein-energy malnutrition.

[Update on the current role of plasma cholinesterase]

The antagonism of steroidal nondepolarizing neuromuscular blockers (NDMBs) moved forward recently with the introduction of sugammadex, the only drug able to immediately reverse the effects of curarization produced by NDMBs. This advance has necessitated reflection on the future role of pseudocholinesterase. In spite of the side effects of succinylcholine and published opinions on its use, this NDMB continues to be used in clinical anesthesia. Pseudocholinesterase is mainly found in the liver, plasma, and nervous system. The enzyme is synthesized in the liver in greater amounts than required although certain conditions lead to deficiency, which is usually asymptomatic. The only clinical expression is the apnea which develops after administration of succinycholine because this NDMB cannot be metabolized. In some patients, slight reductions in the antagonism of succinylcholine lead to rising neuromuscular concentrations of the drug in accordance with the degree and duration of the blockade. We review the various forms of pseudocholinesterase deficiency, including a discussion of genetic variants, clinical manifestations, and management. In addition to discussing the diagnosis of this condition and the clinical implications, we highlight the importance of practice protocols and access to a referral laboratory if one is not available within the immediate hospital.

[Anesthesia and preeclampsia]

An assessment of the patient must take place as early as possible in view of anaesthesia. It is recommended to perform a clotting screen as close as possible to the performing of an epidural anaesthesia. The use of aspirin, if indicated for the prevention of PE, does not as such, constitute a contraindication to performing an epidural anaesthesia if: With regards to the minimum platelet count, the recommended cut-off value for the performing of an epidural and spinal anaesthesia are 75 & 50 x 10(9)/l respectively, only if all of the following conditions are met: It is recommended to quickly set up an epidural anaesthesia because this will improve the blood pressure as well as the utero-placenteric haemodynamics and also because this will facilitate the management in case of a caesarean section. Whereas methylergometrine (Methergin) is contraindicated in the preeclamptic patient, it is possible to use oxytocin (Syntocinion) during and after labour. Before performing a spinal anaesthesia, it is recommended to restrain the administration of crystalloids to a maximum of 1000 ml. Also the i.v. antihypertensive treatment should be reduced or interrupted until complete establishment of the anaesthetic. In case a general anaesthesia is to be performed, an assessment of the criteria for difficult intubation should be performed immediately prior to the induction. The technique employed should be a rapid sequence induction with intubation, while preventing a surge in blood pressure induced by the tracheal intubation. Difficulties to extubate should systematically be anticipated. It is possible to perform a loco-regional anaesthesia following an eclamptic crisis if the following conditions are met: In case of overlapping seizures and/or impaired consciousness, a general anaesthesia is recommended.

Corrected scoliosis, cholinesterase deficiency, and cesarean section: a case report

We describe a patient with severe scoliosis for which corrective surgery was performed at the age of 12. During a previous caesarean section under general anaesthesia pseudocholinesterase deficiency was discovered. Ultrasound guided spinal anaesthesia was performed enabling a second caesarean section under loco-regional anaesthesia.