Big conductance calcium-activated potassium channel openers control spasticity without sedation.

BACKGROUND AND PURPOSE: Our initial aim was to generate cannabinoid agents that control spasticity, occurring as a consequence of multiple sclerosis (MS), whilst avoiding the sedative side effects associated with cannabis. VSN16R was synthesized as an anandamide (endocannabinoid) analogue in an anti-metabolite approach to identify drugs that target spasticity. EXPERIMENTAL APPROACH: Following the initial chemistry, a variety of biochemical, pharmacological and electrophysiological approaches, using isolated cells, tissue-based assays and in vivo animal models, were used to demonstrate the activity, efficacy, pharmacokinetics and mechanism of action of VSN16R. Toxicological and safety studies were performed in animals and humans. KEY RESULTS: VSN16R had nanomolar activity in tissue-based, functional assays and dose-dependently inhibited spasticity in a mouse experimental encephalomyelitis model of MS. This effect occurred with over 1000-fold therapeutic window, without affecting normal muscle tone. Efficacy was achieved at plasma levels that are feasible and safe in humans. VSN16R did not bind to known CB1 /CB2 /GPPR55 cannabinoid-related receptors in receptor-based assays but acted on a vascular cannabinoid target. This was identified as the major neuronal form of the big conductance, calcium-activated potassium (BKCa ) channel. Drug-induced opening of neuronal BKCa channels induced membrane hyperpolarization, limiting excessive neural-excitability and controlling spasticity. CONCLUSIONS AND IMPLICATIONS: We identified the neuronal form of the BKCa channel as the target for VSN16R and demonstrated that its activation alleviates neuronal excitability and spasticity in an experimental model of MS, revealing a novel mechanism to control spasticity. VSN16R is a potential, safe and selective ligand for controlling neural hyper-excitability in spasticity

Investigation of tutin, a naturally-occurring plant toxin, as a novel, culturally-acceptable rodenticide in New Zealand

He nui nga mātauranga a te Māori (Ngai Tūhoe) e pā ana ki nga momo hua tāokeoke (Toxins) etaea ana te whakarite hei rauemi tāwai i ngā riha kīrearea, pērā anō ki nga whiu takarangi o te tāoke 1080. I whakamātauhia e matou i nga ira tāoke o roto o te hua Tutu, ki rō taiwhanga pūtaiao. Mā te wero atu ki tētahi kiore (Norway Rat) i hua mai ngā mohiotanga o te nui me te momo o ngā tāokeoke kei roto i tēnei miro Māori, me te āhua o tēnei tāoke kia mau-rohā tonu tōna tuku whakahemo (Humaneness). Kei tua o te 55 mg kg⁻¹neke atu, te ine i tūtuki pai ai nga tāhawahawatanga o te miro Tutu, ā, e mau-roha tonu ana te kōhurutanga o te r iha. Ko te whakatau kia kawea atu tēnei kaupapa ki nga ahurewa rangahau e taea ai te waihanga i tētahi mōunu tāokeoke, kia whakamātauria ki rō ngāhere. Hei tāpiritanga ki tēnei, he roa rawa te wā e pakari ai te whanaketanga mai o tētahi tākoe e rerekē ana ki te 1080, anō nei, mā ngā kawenga o te mātauranga Māori ki tēnei take e whanake tika ai te kaupapa nei. New Zealand has many introduced mammalian species that are managed as pests of conservation and/or economic importance, including four rodent species. Vertebrate pesticides are the most important rodent management tool, largely dominated by anticoagulants such as brodifacoum, and by the metabolic disruptor, Compound 1080. There has been considerable opposition to these pesticides, primarily based on concerns about environmental persistence and non-target effects; Maori have been particularly vocal in opposition. Maori have place-based knowledge about naturally-occurring plant toxins that could be used as culturally-acceptable alternatives to existing rodenticides. In the context of the research presented here, the term ‘culturally-acceptable’ refers to new pest control options that have been co-designed with Matauranga Maori experts that inherently include Maori ways of thinking, being, and acting. Tuhoe researchers in our study wanted to pursue the most promising natural toxic compound found in native plants as a suitable alternative to current vertebrate pesticides. Therefore, we undertook an oral gavage trial to assess the toxicity of tutin, the toxin active in tutu (Coriaria arborea), to the Norway rat, (Rattus norvegicus). Tutin was toxic to this species at a dose of 55 mg kg⁻¹, with a quick, humane death compared to other existing rodenticides. At a dose rate of 55 mg kg⁻¹, all animals of both sexes died within an hour, and once neurological poisoning symptoms commenced these animals were unconscious within 5-10 minutes. We conclude it is warranted to take the next logical research step, which is to prove whether this dose rate would be technically attainable in the field. Although for now New Zealand remains reliant on 1080 and anti-coagulants for mammalian pest control, efforts should continue to develop more targeted toxins and delivery systems. We recommend incorporating Matauranga Maori to identify alternative control tools that could lead to more culturally acceptable pest control

Spirolides and Cyclic Imines: Toxicological Profile

International audienceIn this chapter, we review available evidence on the toxicological profile of spirolides and other lipophilic cyclic imine toxins, highlighting their chemical structure, the phytoplankton species involved in their production, their pharmacokinetics/toxicokinetics and experimental toxicity, and their molecular targets and mechanisms of action. These phycotoxins belong to an emerging class of chemical agents associated with marine algal blooms and shellfish toxicity. Their chemical structure is represented by a macrocycle, with the ring size between 14 and 27, and two conserved features that include the cyclic imine group and spiroketal ring system. The producers of spirolides, gymnodimines and pinnatoxins have been identified as being the dinoflagellates Alexandrium ostenfeldii/peruvianum, Karenia selliformis and Vulcanodinium rugosum. Their acute toxicity

HIV-1 evades innate immune recognition through specific cofactor recruitment

Human immunodeficiency virus (HIV)-1 is able to replicate in primary human macrophages without stimulating innate immunity despite reverse transcription of genomic RNA into double-stranded DNA, an activity that might be expected to trigger innate pattern recognition receptors. We reasoned that if correctly orchestrated HIV-1 uncoating and nuclear entry is important for evasion of innate sensors then manipulation of specific interactions between HIV-1 capsid and host factors that putatively regulate these processes should trigger pattern recognition receptors and stimulate type 1 interferon (IFN) secretion. Here we show that HIV-1 capsid mutants N74D and P90A, which are impaired for interaction with cofactors cleavage and polyadenylation specificity factor subunit 6 (CPSF6) and cyclophilins (Nup358 and CypA), respectively, cannot replicate in primary human monocyte-derived macrophages because they trigger innate sensors leading to nuclear translocation of NF-κB and IRF3, the production of soluble type 1 IFN and induction of an antiviral state. Depletion of CPSF6 with short hairpin RNA expression allows wild-type virus to trigger innate sensors and IFN production. In each case, suppressed replication is rescued by IFN-receptor blockade, demonstrating a role for IFN in restriction. IFN production is dependent on viral reverse transcription but not integration, indicating that a viral reverse transcription product comprises the HIV-1 pathogen-associated molecular pattern. Finally, we show that we can pharmacologically induce wild-type HIV-1 infection to stimulate IFN secretion and an antiviral state using a non-immunosuppressive cyclosporine analogue. We conclude that HIV-1 has evolved to use CPSF6 and cyclophilins to cloak its replication, allowing evasion of innate immune sensors and induction of a cell-autonomous innate immune response in primary human macrophages. © 2013 Macmillan Publishers Limited. All rights reserved