Memantine is the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, used in the treatment of Alzheimer's disease. It also known that memantine pretreatment assured protection of skeletal muscles from poisoning with nerve agents and an interaction between memantine and AChE was proposed. In the study presented we examined interactions of memantine and its main metabolite (1-amino-3-hydroxymethyl-5-methyl adamantine, Mrz 2/373) with AChE in vitro as well as their effect on kinetics of the soman-induced AChE inhibition and aging. The results have shown that memantine and Mrz 2/373 exerted concentration-dependent inhibition of AChE, with Mrz 2/373 being a more potent inhibitor than the parent compound. Addition of soman 7.5 nmol/l induced gradual AChE inhibition that became almost complete after 20 min. Memantine (0.1, 0.5 and 1 mmol/l) and Mrz 2/373 (0.1, 0.5 and 1 mmol/l) concentration-dependently slowed down the AChE inhibition. After 30 min of incubation of AChE with soman, 5 min of aging and 20 min of reactivation by asoxime (HI-6 dichloride), AChE activity was 8.1% in control medium, 30.7% and 41.9% after addition of 1 and 10 mmol/l memantine, and 16.1% after addition of 1 mmol/l Mrz 2/373. It was concluded that it is possible that memantine and Mrz 2/373 can prevent AChE from inhibition by soman, which could, along with known memantine's neuroprotective activity, explain its potent antidotal effect in soman poisoning. The potential effect on aging of the soman-AChE complex warrants further studies.

Introduction: Oganophosphorus compounds (OP) bind to acetylcholinesterase (AChE) and inactivate it. In the synaptic cleft, undestroyed and accumulated acetylcholine produce the acute cholinergic effects. The aim of this study was to determine the frequency, speed of onset and intensity of certain signs of paraoxon poisoning depending on dose and outcome of poisoning. Methods: The study was conducted in adult Wistar rats. The median lethal dose (LD50) of paraoxon as well as protective ratio (PR) of atropine (10 mg/kg intramuscularly) was determined. Clinical signs of poisoning were observed: fasciculations, tremor, seizures, ataxia, piloerection, lacrimation, exophthalmos, bizzare/stereotypic behaviour and dyspnoea. The time from paraoxon injection to the first appearance of the sign of poisoning was recorded as well as the intensity of poisoning with evaluation at 10 time intervals throughout the 4 h observational period. Results: The LD50 of paraoxon was 0.33 mg/kg (subcutaneously) and PR of atropine was 2.73. Dose-dependent, piloerection occurred more often (p = 0.009) and at higher intensity (p = 0.016) at higher doses. Fasciculations, tremor, seizures and ataxia occurred significantly earlier at higher doses of paraoxon (p = 0.015, 0.002, 0.021 and 0.016, respectively), as well as the intensity of seizure, tremor and fasciculation. Piloerection (p = 0.002) and seizures occurred more frequently (p = 0.009) in non-survivors. Fasciculations, tremor, seizures and ataxia occurred significantly earlier and at higher intensity in non-survivors (p < 0.001, for all parameters), as well as dyspnoea (p = 0.009 and p = 0.048). In atropine-protected rats, nicotinic effects persevered, so they were the prognostic parameter of the severity of the poisoning. Conclusion: Seizures and fasciculations followed by tremor were strong prognostic parameters of the probability of lethal outcome of paraoxon poisoning. Also, the mentioned poisoning signs were with their intensity and speed of occurrence in a clear positive correlation with the administered dose of paraoxon. Even at high doses of paraoxon, atropine blocked the muscarinic (but not nicotinic) effects and somewhat mitigated the CNS toxic effects.

The search for effective coronavirus disease (COVID-19) therapy has attracted a great deal of scientific interest due to its unprecedented health care system overload worldwide. We have carried out a study to investigate the in silico effects of the most abundant pomegranate peel extract constituents on the multi-step process of serious acute respiratory syndrome coronavirus 2 (SARS-CoV-2) internalization in the host cells. Binding affinities and interactions of ellagic acid, gallic acid, punicalagin and punicalin were studied on four selected protein targets with a significant and confirmed role in the process of the entry of virus into a host cell. The protein targets used in this study were: SARS-CoV-2 spike glycoprotein, angiotensin-converting enzyme 2, furin and transmembrane serine protease 2. The results showed that the constituents of pomegranate peel extracts, namely punicalagin and punicalin had very promising potential for significant interactions with the selected protein targets and were therefore deemed good candidates for further in vitro and in vivo evaluation.

In Issues 1 and 2 the scientific biomedical journal Scripta Medica devoted a total of six articles to the aetiological, epidemiological and clinial aspects of serious acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease caused by this virus coronavirus disease 2019 (COVID-19). The present Issue 2 also contains an obituary on the occasion of demise of Professor Folke Sjöqvist, one of the founding fathers of clinical pharmacology as a discipline and several other articles from the fields of quality assurance in healthcare, experimental and clinical medicine.

Abstract Carboxylesterases (CarbE) represent an important factor in studying the new antidotes against G-agents, tabun, sarin, and especially soman. Its isoenzymes exist in many mammalian tissues, but the most important is blood, as it is a medium for transportation of nerve agents to the target organs, such as the central nervous system and respiratory muscles. Rodent species used extensively in such research contain high plasma CarbE activity (mice, rats) or medium level (guinea pigs). At the same time, a low level of plasma CarbE activity was found in marmosets and there was practically no such activity in the plasma of rhesus monkeys and humans. In order to obtain results that would be easily extrapolated to humans, either nonhuman primates with naturally minimal plasma CarbE activity or rodents pretreated with CarbE inhibitors (TOCP, CBDP) should be utilized. In such animals, the LD50 of nerve agents is very similar, as is the efficacy of the prophylactic/postexposure antidotes. CarbEs are also potential stoichiometric scavengers of nerve agents and can be used intravenously to bind organophosphorus compound molecules.

Abstract Pomegranate peel contains high levels of various phytochemicals. We evaluated the effects of pomegranate peel extract (PoPEx) consumption on plasma lipid profile, fatty acids (FA) level and blood pressure (BP) in patients with diabetes mellitus type 2 (DMT2). Thirty-seven subjects were recruited in this double blind, placebo controlled randomized trial. The study group (n = 19) received over 8 week’s capsules containing PoPEx twice a daily, while the placebo group received placebo. Treatment with PoPEx induced a significant lowering of both systolic and diastolic BP. The plasma levels of triglycerides, low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio (LDL-C/HDL-C), and HbA1c were significantly decreased, while the level of HDL-C was significantly increased, compared with placebo intake. Moreover, the PoPEX treatment significantly improved the plasma lipids fatty acids content. It is concluded that consumption of PoPEx in DMT2 subject had favourable effects on some metabolic parameters, BP, lipid profile and plasma lipid FA composition.

This editorial presents the analysis of volumes 50 (2019) and 51 (2020) of Scripta Medica. Original articles made 53 % of 80 articles published in these two volumes. Article rejection rate was 38 %. Mean duration of period until reaching the first decision on an article was 20 days, while mean time until reaching the final decision was 31 days. Mean time needed for accepting the revised manuscript was 3 days, reflecting a significant decrease from 5 days in 2019 to 2 days in 2020. Mean time needed for reaching a decision to reject an article was 7 days. Coverage of the journal included both basic and clinical research and a considerable space was devoted to articles on COVID-19. Further efforts will be made in order to reach a more international recognition of the journal.

Abstract Prophylactic antidotes are needed primarily in the case of soman poisoning, since its complex with acetylcholinesterase (AChE) ages very quickly and becomes resistant to the posttherapeutic administration of AChE reactivators. Among the many compounds tried as prophylactic antidotes, reversible AChE inhibitors (physostigmine, pyridostigmine, galantamine and huperzine A), noncompetitive antagonists of NMDA/AMPA receptors for excitatory amino acid glutamine (memantine, dizocilpine, procyclidine, ketamine), transdermal patches with a combination of physostigmine and procyclidine or patches with asoxime and stoichiometric and catalytic scavengers of nerve agents gave best results. Postexposure treatment of nerve agent intoxication consists of a triple regimen: anticholinergics, AChE reactivators, and anticonvulsants. Antimuscarinics, mainly atropine, but also more liposoluble scopolamine, oximes pralidoxime (2-PAM, P2S), trimedoxime (TMB-4), obidoxime LuH-6, asoxime (HI-6), HLo-7 and, most recently, K-oximes and benzodiazepines, diazepam, midazolam, and clonazepam, are discussed. Special attention is paid to glutamate receptor antagonists, memantine, ketamine, and procyclidine, as anticonvulsants that prevent the perpetuation of seizures following poisoning with nerve agents.

This study reviews the current understanding of chemical and biochemical mechanisms of metabolism of warfare nerve agents and describes the role of the enzymes involved in this process. Among enzymes participating in the metabolism of nerve agents, the roles of A-esterases, serum cholinesterase, carboxylesterase, and prolidase are discussed.

Organophosphorus (OP) compounds have been used as pesticides and have been developed as warfare nerve agents such as tabun, soman, sarin, VX, and others. Exposure to even small amounts of an OP compound can be fatal and death is usually caused by respiratory failure resulting from paralysis of the diaphragm and intercostal muscles, depression of the brain respiratory center, bronchospasm, and excessive bronchial secretions. The mechanism of OP poisoning involves phosphorylation of the serine hydroxyl group in the active site of acetylcholinesterase (AChE), leading to the inactivation of this essential enzyme, which has an important role in neurotransmission. AChE inhibition results in the accumulation of acetylcholine at cholinergic receptor sites, producing continuous stimulation of cholinergic fibers throughout the central and peripheral nervous systems. Presently, a combination of an antimuscarinic agent (e.g., atropine), AChE reactivator such as one of the recommended pyridinium oximes (PAM-2, TMB-4, HI-6, LuH-6), and diazepam are used for the treatment of organophosphate poisoning in humans. In this chapter, we review the mechanisms of action of OP and the role of pyridinium oximes used as AChE reactivators in the treatment of OP poisoning.

BACKGROUND Carbamates physostigmine and pyridostigmine have been used as a pretreatment against poisoning with nerve agents in order to reversibly inhibit and thus protect from irreversible inhibition a portion of acetylcholinesterase (AChE) in brain and respiratory muscles that is crucial for survival. Memantine, an adamantine derivative, has emerged as a promising alternative to carbamates, since it prevented the fasciculations and skeletal muscle necrosis induced by carbamates and organophosphates, including nerve agents. AIM This experimental study was undertaken in order to investigate and compare the protective and behavioural effects of memantine and standard carbamates physostigmine and pyridostigmine in rats poisoned with soman and treated with atropine, oxime HI-6 and diazepam. Another goal was to elucidate the mechanisms of the antidotal effect of memantine and its potential synergism with standard antidotes against nerve agents. MATERIALS AND METHODS Male Wistar rats were used throughout the experiments. In dose-finding experiments memantine was administered at dose interval 0-72 mg/kg sc 60 min before sc injection of soman. In time-finding experiments memantine was injected 18 mg/kg sc 0-1440 min before soman. Standard treatment antidotes - atropine 10 mg/kg, HI-6 50 mg/kg and diazepam 2.5 mg/kg - were administered im within 15 s post-exposure. Soman 0.75 LD50 was used to study its inhibitions of neuromuscular transmission on the phrenic nerve-diaphragm preparation in situ and of tissue AChE activity. Behavioural effects of the prophylactic antidotes were investigated by means of the rotarod test. Based on these data therapeutic index and therapeutic width was calculated for all three prophylactic agents. RESULTS Memantine pretreatment (18 mg/kg sc) produced in rats poisoned with soman significantly better protective ratios (PRs) than the two carbamates - 1.25 when administered alone and 2.3 when combined with atropine pretreatment and 6.33 and 7.23 with atropine/HI-6 and atropine/HI-6/diazepam post-exposure therapy, respectively. The highest PR of 10.11 obtained in Atr/HI-6-treated rats was achieved after pretreatment with memantine 36 mg/kg. This additional protection lasted for 8 h. All three prophylactic regimens antagonised the soman-induced neuromuscular blockade, but the effect of memantine was fastest. Pretreatment with memantine assured higher AChE activity in brain and diaphragm than in unpretreated rats (46% vs 28% and 68% vs. 38%, respectively). All three prophylactic regimens affected the rotarod performance in rats, but the effect of memantine was relatively strongest. Memantine and pyridostigmine had lowest and highest therapeutic index and therapeutic width, respectively. CONCLUSIONS Although memantine assures better and longer-lasting protection against soman poisoning in rats than the two carbamates, its small therapeutic index and narrow therapeutic width seriously limit its potential as a pretreatment agent. Despite its behavioural effects, memantine seems to be beneficial antidote when administered after soman, along with atropine/HI-6/diazepam therapy. Mechanism of the antidotal effect of memantine against soman poisoning appears to be a combination of AChE-protecting and NMDA receptor-blocking action.

Background: The purpose of this study was to assess the antiviral efficacy and safety of the direct-acting antivirals (DAAs) in therapy of chronic hepatitis C virus (HCV) infection. Methods: This real-life multi-centric study was performed at the Clinic for Infectious Diseases, University Clinical Centre of the Republic of Srpska, Banja Luka and it included a total of 89 patients. All patients received the adequate doses of ombitasvir (OBV)/ paritaprevir (PTV)/ritonavir (RTV) + dasabuvir (DSV) plus ribavirin (RBV). RBV was given to all patients except to those with HCV sub-genotype 1b. DSV was not administered to patients infected with HCV genotype 4. For the majority of patients the treatment duration was 12 weeks. For ten patients with liver cirrhosis the duration of treatment was 24 weeks. Viraemia was assessed at three points in time: at baseline, 12 or 24 weeks after the beginning of treatment (end of treatment response ETR), and 12 weeks after the end of treatment (sustained viral response SVR). Results: Complete ETR after 12 weeks of treatment was achieved in 79 patients, while in 10 high-risk patients it was achieved after 24 weeks of treatment. Full SVR was recorded in 88 patients 12 weeks after the end of treatment. This therapy was well tolerated and mild adverse effects were recorded in only 10 patients. Conclusion: Treatment of patients with chronic HCV infection with OBV/PTV/ RTV+ DSV + RBV resulted in excellent antiviral activity and mild adverse events.