Distribution of chromaffin secretory vesicles, acetylcholinesterase, and lysosomal enzymes in sucrose and percoll gradients

Crude chromaffin secretory vesicles, obtained by differential centrifugation, were further purified on isotonic (Percoll) gradients. The chromaffin vesicle fractions recovered from the gradients contain acetylcholinesterase as well as lysosomal enzymes. With the aid of a subsequent sucrose gradient lysosomal enzymes could be removed from chromaffin vesicle fractions, but not acetylcholinesterase. This suggests that lysosomal enzymes do not pass through the chromaffin vesicles during the biogenesis of lysosomes but acetylcholinesterase does

Pralidoxime in Acute Organophosphorus Insecticide Poisoning-A Randomised Controlled Trial

Background: Poisoning with organophosphorus (OP) insecticides is a major global public health problem, causing an estimated 200,000 deaths each year. Although the World Health Organization recommends use of pralidoxime, this antidote's effectiveness remains unclear. We aimed to determine whether the addition of pralidoxime chloride to atropine and supportive care offers benefit. Methods and Findings: We performed a double-blind randomised placebo-controlled trial of pralidoxime chloride (2 g loading dose over 20 min, followed by a constant infusion of 0.5 g/h for up to 7 d) versus saline in patients with organophosphorus insecticide self-poisoning. Mortality was the primary outcome; secondary outcomes included intubation, duration of intubation, and time to death. We measured baseline markers of exposure and pharmacodynamic markers of response to aid interpretation of clinical outcomes. Two hundred thirty-five patients were randomised to receive pralidoxime (121) or saline placebo (114). Pralidoxime produced substantial and moderate red cell acetylcholinesterase reactivation in patients poisoned by diethyl and dimethyl compounds, respectively. Mortality was nonsignificantly higher in patients receiving pralidoxime: 30/121 (24.8%) receiving pralidoxime died, compared with 18/114 (15.8%) receiving placebo (adjusted hazard ratio HR] 1.69, 95% confidence interval CI] 0.88-3.26, p = 0.12). Incorporating the baseline amount of acetylcholinesterase already aged and plasma OP concentration into the analysis increased the HR for patients receiving pralidoxime compared to placebo, further decreasing the likelihood that pralidoxime is beneficial. The need for intubation was similar in both groups (pralidoxime 26/121 21.5%], placebo 24/114 21.1%], adjusted HR 1.27 95% CI 0.71-2.29]). To reduce confounding due to ingestion of different insecticides, we further analysed patients with confirmed chlorpyrifos or dimethoate poisoning alone, finding no evidence of benefit. Conclusions: Despite clear reactivation of red cell acetylcholinesterase in diethyl organophosphorus pesticide poisoned patients, we found no evidence that this regimen improves survival or reduces need for intubation in patients with organophosphorus insecticide poisoning. The reason for this failure to benefit patients was not apparent. Further studies of different dose regimens or different oximes are required

Latent acetylcholinesterase in secretory vesicles isolated from adrenal medulla

A new procedure is described for the preparation of highly purified and stable secretory vesicles from adrenal medulla. Two forms of acetylcholinesterase, a membrane bound form as well as a soluble form, were found within these vesicles. The secretory vesicles, isolated by differential centrifugation, were further purified on a continuous isotonic Percoll™ gradient. In this way, secretory vesicles were separated from mitochondrial, microsomal and cell membrane contamination. The secretory vesicles recovered from the gradient contained an average of 2.26 μmol adrenalin/mg protein. On incubation for 30 min at 37°C in media differing in ionic strength, pH, Mg2+ and Ca2+ concentration, the vesicles released less than 20% of total adrenalin. Acetylcholinesterase could hardly be detected in the secretory vesicle fraction when assayed in isotonic media. However, in hypotonic media (<400 mosmol/kg) or in Triton X-100 (0.2% final concentration) acetylcholinesterase activity was markedly higher. During hypotonic treatment or when secretory vesicles were specifically lyzed with 2 mM Mg2+ and 2 mM ATP, adrenalin as well as part of acetylcholinesterase was released from the vesicular content. On polyacrylamide gel electrophoresis this soluble enzyme exhibited the same electrophoretic mobility as the enzyme released into the perfusate from adrenal glands upon stimulation. In addition to the soluble enzyme a membrane bound form of acetylcholinesterase exists within secretory vesicles, which sediments with the secretory vesicle membranes and exhibits a different electrophoretic mobility compared to the soluble enzyme. It is concluded, that the soluble enzyme found within isolated secretory vesicles is secreted via exocytosis, whilst the membrane-bound form is transported to the cell membrane during this process, contributing to the biogenesis of the cell membrane

Stability and enzymatic studies with omeprazole: hydroxypropyl-β-cyclodextrin

The original publication is available at www.springerlink.com. A publicação original está disponível em www.springerlink.comOmeprazole (OME) exhibits low stability to light, heat and humidity. In stress conditions OME stability should improve under inclusion complex form with hydroxypropyl-b-cyclodextrin (HPbCD). Stability of OME, its physical mixture (PM) with HPbCD and OME:HPbCD inclusion complex was assessed during 60 days. The inclusion complexes were prepared by kneading and freezedrying techniques and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). A molecular modelling was also held to predict the most probable tridimensional conformation of inclusion complex OME:HPbCD. The inhibitory activity of free and complexed OME on selected enzymes, namely, papain (protease model of the proton pump) and acetylcholinesterase (enzyme present in cholinergic neurons and also involved in Alzheimer’s disease) was compared. The results obtained show that HPbCD do not protect against OME degradation, in any prepared powder, in the presence of light, heat and humidity. This may indicate that the reactive group of OME is not included in the HPbCD cavity. This fact is supported by molecular modelling data, which demonstrated that 2-pyridylmethyl group of OME is not included into the cyclodextrin cavity. In relation to enzymatic assays it was observed that free OME and OME in the binary systems showed identical inhibitory activity on papain and acethylcolinesterase, concluding that HPbCD do not affect OME activity on these two enzymes

New N,N-dimethylcarbamate inhibitors of acetylcholinesterase: design synthesis and biological evaluation

A series of N,N-dimethylcarbamates containing a N,N-dibenzylamino moiety was synthesized and tested to evaluate their ability to inhibit Acetylcholinesterase (AChE). The most active compounds 4 and 8, showed 85 and 69% of inhibition at 50 mM, respectively. Furthermore, some basic SAR rules were outlined: an alkyl linker of six methylene units is the best spacer between the carbamoyl and dibenzylamino moieties; electron-withdrawal substituents on aromatics rings of the dibenzylamino group reduce the inhibitory power. Compound 4 produces a slow onset inhibition of AChE and this is not due to the carbamoylation of the enzyme, as demonstrated by the time-dependent inhibition assay of AChE with compound 4 and by MALDI-TOF MS analysis of trypsinized AChE inhibited by compound 4. Instead, compound 4 could act as a slow-binding inhibitor of AChE, probably because of its high conformational freedom due to the linear alkyl chain

The influence of in vitro gastrointestinal digestion on the chemical composition and antioxidant and enzyme inhibitory capacities of carob liqueurs obtained with different elaboration techniques

Carob liqueur is a traditional Mediterranean alcoholic beverage obtained via a wide range of production techniques contributing to the different organoleptic attributes of the final product. The aim of this research was to evaluate the stability of the chemical composition and biological capacities (antioxidant and enzyme inhibition) under in vitro simulated gastrointestinal digestion of liqueurs prepared by flavouring the fig spirit with carob pulp by maceration, distillation, percolation, or aqueous and hydro-alcoholic infusions. For this purpose, the phenolic and furanic compositions, the total phenolic (TPC) and flavonoid (TFC) contents, antioxidant capacity (AC), and enzyme inhibitory potential against acethylcholinesterase, tyrosinase, α-glucosidase and α-amylase enzymes were evaluated. The content of gallic acid decreased after gastrointestinal digestion, while TPC, TFC, and AC significantly increased after each digestion phase. Overall, no significantly different enzyme inhibitions (p < 0.05) were observed among digested liqueurs, with moderate inhibition against acethylcholinesterase and tyrosinase (enzymes related with neurodegenerative diseases), and potent and low inhibitory capacities for α-glucosidase and α-amylase, respectively (ideal conditions employed in antidiabetic therapy). The study indicates that hydro-alcoholic infusion and maceration were the most appropriate methods to obtain liqueurs with higher values of the aforementioned parameters and safe levels of toxic furanics.Fundação para a Ciência e a Tecnologia, I.P.: SFRH/BPD/103086/2014; DL 57/2016/CP1361/CT0022; project INTERREG-MD.NET: When Brand Meets Peopleinfo:eu-repo/semantics/publishedVersio

Pharmacotherapeutic aspects of dementia care in Malta

Dementia is the most common neurodegenerative disorder of old age affecting one percent of the local general population. It is a major predictor of morbidity and mortality in the elderly, adding a significant burden on health and social care systems across Europe. The financial impact of caring for individuals with dementia is considerable and progressive loss of cognitive function does not only pose challenges to the patients but also adds significant strain on the well-being of caregivers and family members. Although no cure is available, disease progression can be delayed by early intervention and by the use of pharmacotherapeutic agents that interfere with central neurotransmitter systems involved in cognitive processes. This review presents current trends in pharmacotherapeutic intervention in dementia care together with caregiver perceptions on treatment expectations in Malta.peer-reviewe

Adverse Effects of Cholinesterase Inhibitors in Dementia, According to the Pharmacovigilance Databases of the United-States and Canada.

This survey analyzes two national pharmacovigilance databases in order to determine the major adverse reactions observed with the use of cholinesterase inhibitors in dementia. We conducted a statistical analysis of the Food and Drug Administration Adverse Event Reporting System (FAERS) and the Canada Vigilance Adverse Reaction Database (CVARD) concerning the side effects of cholinesterase inhibitors. The statistics calculated for each adverse event were the frequency and the reporting odds ratios (ROR). A total of 9877 and 2247 reports were extracted from the FAERS and CVARD databases, respectively. A disproportionately higher frequency of reports of death as an adverse event for rivastigmine, compared to the other acetylcholinesterase inhibiting drugs, was observed in both the FAERS (ROR = 3.42; CI95% = 2.94-3.98; P&lt;0.0001) and CVARD (ROR = 3.67; CI95% = 1.92-7.00; P = 0.001) databases. While cholinesterase inhibitors remain to be an important therapeutic tool against Alzheimer's disease, the disproportionate prevalence of fatal outcomes with rivastigmine compared with alternatives should be taken into consideration

Beyond Cholinesterase Inhibition. Anti-Inflammatory Role and Pharmacological Profile of Current Drug Therapy for Alzheimer's Disease

Inflammation is a common response of an individual against either exogenous or endogenous damage. The role of inflammation and of inflammatory cells recently emerged also in the pathogenesis of neurodegenerative disorders. Experimental evidences show how neurotransmitters, besides their role in the synapses, play a modulatory role during immune response. Drugs used for treatment of dementia symptoms are able to increase neurotransmitters levels, and likely to have a modulatory role during immune response. Aim of this review is to discuss the most recent advances on inflammation role during neurodegeneration and also to individuate the potential anti-inflammatory role played by drugs currently used for Alzheimer's disease treatment