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https://www.readbyqxmd.com/read/28535116/is-mannitol-the-treatment-of-choice-for-patients-with-ciguatera-fish-poisoning
#1
Michael E Mullins, Robert S Hoffman
CONTEXT: Ciguatera fish poisoning arises primarily from consumption of carnivorous reef fish caught in tropical and sub-tropical waters. Ciguatoxins, a class of tasteless, heat-stable, polycyclic toxins produced by dinoflagellates, accumulate through the food chain and concentrate in various carnivorous fish, such as groupers, barracudas, wrasses, amberjack, kingfishes, and eels. Characteristics of ciguatera fish poisoning include early nausea, vomiting, and diarrhea in the first one to two days post ingestion, followed by the appearance of sensory disturbances...
May 23, 2017: Clinical Toxicology
https://www.readbyqxmd.com/read/28528671/voltage-gated-sodium-channel-pharmacology-insights-from-molecular-dynamics-simulations
#2
Rong Chen, Amanda Buyan, Ben Corry
Voltage-gated ion channels are the target of a range of naturally occurring toxins and therapeutic drugs. There is a great interest in better understanding how these diverse compounds alter channel function in order to design the next generation of therapeutics that can selectively target one of the channel subtypes found in the body. Since the publication of a number of bacterial sodium channel structures, molecular dynamics simulations have been invaluable in gaining a high resolution understanding where many of these small molecules and toxins bind to the channels, how they find their binding site, and how they can selectively bind to one channel subtype over another...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28528669/modulation-of-ion-channels-by-cysteine-rich-peptides-from-sequence-to-structure
#3
Mehdi Mobli, Eivind A B Undheim, Lachlan D Rash
Venom peptides are natural ligands of ion channels and have been used extensively in pharmacological characterization of various ion channels and receptors. In this chapter, we survey all known venom peptide ion-channel modulators. Our survey reveals that the majority of venom peptides characterized to date target voltage-gated sodium or potassium channels. We further find that the majority of these peptides are found in scorpion and spider venoms. We discuss the influence of the pharmacological tools available in biasing discovery and the classical "toxin-to-sequence" approach to venom peptide biodiscovery...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28526576/carvacrol-promotes-neuroprotection-in-the-mouse-hemiparkinsonian-model
#4
L M Dati, H Ulrich, C C Real, Z P Feng, H S Sun, L R Britto
Carvacrol is a monoterpene that has been linked to neuroprotection in several animal models of neurodegeneration, including ischemia, epilepsy and traumatic neuronal injury. In this study, we investigated the effects of carvacrol (i.p.) upon the neurodegeneration induced by 6-hydroxy-dopamine unilateral intrastriatal injections in mice. We have also used the cylinder test to assess the behavioral effects of carvacrol in that model of Parkinson's disease, and immunoblots to evaluate the levels of caspase-3 and TRPM7, one of major targets of carvacrol...
May 17, 2017: Neuroscience
https://www.readbyqxmd.com/read/28526335/the-spider-toxin-ph%C3%AE-1%C3%AE-recombinant-possesses-strong-analgesic-activity
#5
Flavia Karine Rigo, Gabriela Trevisan, Samira Dal-Toé De Prá, Marta Nascimento Cordeiro, Marcia Helena Borges, Juliana Figueiredo Silva, Flavia Viana Santa Cecilia, Alessandra Hubner de Souza, Gabriela de Oliveira Adamante, Alessandra Marcon Milioli, Célio José de Castro Junior, Juliano Ferreira, Marcus Vinicius Gomez
The native Phα1β - a Voltage-Gated Calcium Channel (VGCC) blocker - and its Recombinant Version - were both tested in rodent pain models with an intraplantar injections of capsaicin or formalin, a chronic constriction injury, and melanoma cancer related pain. The formalin nociceptive behaviour in the neurogenic phase was not affected by the toxin pre-treatments, while in the inflammatory phase, Phα1β and the Recombinant form caused a significant reduction. The nociception that was triggered by capsaicin, an agonist of the TRPV1 vanilloid receptor, was totally blocked by 100 pmol/site, i...
May 17, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28502745/pi5-and-pi6-two-undescribed-peptides-from-the-venom-of-the-scorpion-pandinus-imperator-and-their-effects-on-k-channels
#6
T Olamendi-Portugal, A Csoti, J M Jimenez-Vargas, F Gomez-Lagunas, G Panyi, L D Possani
This work reports the isolation, chemical and functional characterization of two previously unknown peptides purified from the venom of the scorpion Pandinus imperator, denominated Pi5 and Pi6. Pi5 is a classical K(+)-channel blocking peptide containing 33 amino acid residues with 4 disulfide bonds. It is the first member of a new subfamily, here defined by the systematic number α-KTx 24.1. Pi6 is a peptide of unknown real function, containing only two disulfide bonds and 28 amino acid residues, but showing sequence similarities to the κ-family of K-channel toxins...
May 11, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28499580/transient-receptor-potential-trp-channels-as-molecular-targets-in-lung-toxicology-and-associated-diseases
#7
REVIEW
Alexander Dietrich, Dirk Steinritz, Thomas Gudermann
The lungs as the gateways of our body to the external environment are essential for gas exchange. They are also exposed to toxicants from two sides, the airways and the vasculature. Apart from naturally produced toxic agents, millions of human made chemicals were produced since the beginning of the industrial revolution whose toxicity still needs to be determined. While the knowledge about toxic substances is increasing only slowly, a paradigm shift regarding the proposed mechanisms of toxicity at the plasma membrane emerged...
April 26, 2017: Cell Calcium
https://www.readbyqxmd.com/read/28497266/an-insecticidal-toxin-from-nephila-clavata-spider-venom
#8
Lin Jin, Mingqian Fang, Mengrou Chen, Chunling Zhou, Rose Ombati, Md Abdul Hakim, Guoxiang Mo, Ren Lai, Xiuwen Yan, Yumin Wang, Shilong Yang
Spiders are the most successful insect predators given that they use their venom containing insecticidal peptides as biochemical weapons for preying. Due to the high specificity and potency of peptidic toxins, discoveries of insecticidal toxins from spider venom have provided an opportunity to obtain natural compounds for agricultural applications without affecting human health. In this study, a novel insecticidal toxin (μ-NPTX-Nc1a) was identified and characterized from the venom of Nephila clavata. Its primary sequence is GCNPDCTGIQCGWPRCPGGQNPVMDKCVSCCPFCPPKSAQG which was determined by automated Edman degradation, cDNA cloning, and MS/MS analysis...
May 11, 2017: Amino Acids
https://www.readbyqxmd.com/read/28488084/loop-diuretics-diminish-hemolysis-induced-by-%C3%AE-hemolysin-from-escherichia-coli
#9
Carl Martin Söderström, Steen K Fagerberg, Mette B Brogaard, Jens Leipziger, Marianne Skals, Helle A Praetorius
Uropathogenic Escherichia coli often produce the virulence factor α-hemolysin (HlyA), and the more severe the infection, the likelier it is to isolate HlyA-producing E. coli from patients. HlyA forms pores upon receptor-independent insertion of the toxin into biological membranes and it has been substantiated that HlyA-induced hemolysis is amplified by toxin-induced ATP release and activation of P2X receptors. Thus, hemolysis inflicted by HlyA is a protracted process involving signal transduction. It consists of early, marked cell shrinkage followed by swelling and eventually lysis...
May 9, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/28475112/insect-active-toxins-with-promiscuous-pharmacology-from-the-african-theraphosid-spider-monocentropus-balfouri
#10
Jennifer J Smith, Volker Herzig, Maria P Ikonomopoulou, Sławomir Dziemborowicz, Frank Bosmans, Graham M Nicholson, Glenn F King
Many chemical insecticides are becoming less efficacious due to rising resistance in pest species, which has created much interest in the development of new, eco-friendly bioinsecticides. Since insects are the primary prey of most spiders, their venoms are a rich source of insect-active peptides that can be used as leads for new bioinsecticides or as tools to study molecular receptors that are insecticidal targets. In the present study, we isolated two insecticidal peptides, µ/ω-TRTX-Mb1a and -Mb1b, from venom of the African tarantula Monocentropus balfouri...
May 5, 2017: Toxins
https://www.readbyqxmd.com/read/28457591/from-mucolipidosis-type-iv-to-ebola-trpml-and-two-pore-channels-at-the-crossroads-of-endo-lysosomal-trafficking-and-disease
#11
REVIEW
Christian Grimm, Elisabeth Butz, Cheng-Chang Chen, Christian Wahl-Schott, Martin Biel
What do lysosomal storage disorders such as mucolipidosis type IV have in common with Ebola, cancer cell migration, or LDL-cholesterol trafficking? LDL-cholesterol, certain bacterial toxins and viruses, growth factors, receptors, integrins, macromolecules destined for degradation or secretion are all sorted and transported via the endolysosomal system (ES). There are several pathways known in the ES, e.g. the degradation, the recycling, or the retrograde trafficking pathway. The ES comprises early and late endosomes, lysosomes and recycling endosomes as well as autophagosomes and lysosome related organelles...
April 23, 2017: Cell Calcium
https://www.readbyqxmd.com/read/28450535/sodium-channel-nav1-8-underlies-ttx-resistant-axonal-action-potential-conduction-in-somatosensory-c-fibers-of-distal-cutaneous-nerves
#12
A H Klein, A Vyshnevska, T V Hartke, R De Col, J L Mankowski, B P Turnquist, F Bosmans, P W Reeh, M Schmelz, R W Carr, M Ringkamp
Voltage-gated sodium (NaV) channels are responsible for the initiation and conduction of action potentials within primary afferents. The nine NaV channel isoforms recognized in mammals are often functionally divided into tetrodotoxin (TTX)-sensitive (TTX-s) channels (NaV1.1-NaV1.4, NaV1.6-NaV1.7) that are blocked by nanomolar concentrations and TTX-resistant (TTX-r) channels (NaV1.8 and NaV1.9) inhibited by millimolar concentrations, with NaV1.5 having an intermediate toxin sensitivity. For small-diameter primary afferent neurons, it is unclear to what extent different NaV channel isoforms are distributed along the peripheral and central branches of their bifurcated axons...
April 27, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28428547/the-tarantula-toxin-%C3%AE-%C3%AE-trtx-pre1a-highlights-the-importance-of-the-s1-s2-voltage-sensor-region-for-sodium-channel-subtype-selectivity
#13
Joshua S Wingerd, Christine A Mozar, Christine A Ussing, Swetha S Murali, Yanni K-Y Chin, Ben Cristofori-Armstrong, Thomas Durek, John Gilchrist, Christopher W Vaughan, Frank Bosmans, David J Adams, Richard J Lewis, Paul F Alewood, Mehdi Mobli, Macdonald J Christie, Lachlan D Rash
Voltage-gated sodium (NaV) channels are essential for the transmission of pain signals in humans making them prime targets for the development of new analgesics. Spider venoms are a rich source of peptide modulators useful to study ion channel structure and function. Here we describe β/δ-TRTX-Pre1a, a 35-residue tarantula peptide that selectively interacts with neuronal NaV channels inhibiting peak current of hNaV1.1, rNaV1.2, hNaV1.6, and hNaV1.7 while concurrently inhibiting fast inactivation of hNaV1.1 and rNaV1...
April 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28428070/no-production-and-potassium-channels-activation-induced-by-crotalus-durissus-cascavella-underlie-mesenteric-artery-relaxation
#14
S S Santos, R L C Jesus, L O Simões, W P Vasconcelos, I A Medeiros, R C Veras, L L Casais-E-Silva, D F Silva
Animal toxins are natural resources for pharmacological studies. The venom of Crotalus durissus cascavella (C.d. cascavella) may be a source in the bio-prospecting of new anti-hypertensive agents. The aim of this study was to investigate vascular effects of the venom of C.d. cascavella in normotensive rats. Studies were performed using isolated mesenteric artery segments and aortic endothelial cells. The cumulative administration of the venom of C.d. cascavella (0.001-30 μg/mL) on phenylephrine (Phe; 10 μM) pre-contracted rings induced a concentration-dependent vasorelaxation in the presence of vascular endothelium (Emax = 47...
April 18, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28426823/observation-of-%C3%AF-pore-currents-in-mutant-hkv1-2_v370c-potassium-channels
#15
Pavel Tyutyaev, Stephan Grissmer
Current through the σ-pore was first detected in hKv1.3_V388C channels, where the V388C mutation in hKv1.3 channels opened a new pathway (σ-pore) behind the central α-pore. Typical for this mutant channel was inward current at potentials more negative than -100 mV when the central α-pore was closed. The α-pore blockers such as TEA+ and peptide toxins (CTX, MTX) could not reduce current through the σ-pore of hKv1.3_V388C channels. This new pathway would proceed in parallel to the α-pore in the S6-S6 interface gap...
2017: PloS One
https://www.readbyqxmd.com/read/28416444/the-pharmacology-of-voltage-gated-sodium-channel-activators
#16
REVIEW
Jennifer R Deuis, Alexander Mueller, Mathilde R Israel, Irina Vetter
Toxins and venom components that target voltage-gated sodium (NaV) channels have evolved numerous times due to the importance of this class of ion channels in the normal physiological function of peripheral and central neurons as well as cardiac and skeletal muscle. NaV channel activators in particular have been isolated from the venom of spiders, wasps, snakes, scorpions, cone snails and sea anemone and are also produced by plants, bacteria and algae. These compounds have provided key insight into the molecular structure, function and pathophysiological roles of NaV channels and are important tools due to their at times exquisite subtype-selectivity...
April 14, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28415833/molecular-characterization-and-biodiversity-of-a-putative-chlorotoxin-from-the-iranian-yellow-scorpion-odontobuthus-doriae
#17
Maryam Naderi Soorki, Amir Jalali, Hamid Galehdari
BAckground: Chloride channels have already been over-expressed in the different types of cancer. Chlorotoxins, as the blocking agent of these channels, have been indicated to be an effective drug against tumors. In this study, we characterized a putative chlorotoxin from a cDNA library of the venom glands obtained from the Iranian scorpion Odontobuthus doriae. Methods: A cDNA library was constructed from venom gland transcriptome of six scorpions. The cDNA encoding Odontobuthus doriae chlorotoxin was isolated from the library, and its putative peptide was characterized by some bioinformatics software such as protein blast, SignalP4...
April 18, 2017: Iranian Biomedical Journal
https://www.readbyqxmd.com/read/28410268/long-term-anti-itch-effect-of-botulinum-neurotoxin-a-is-associated-with-downregulation-of-trpv1-and-trpa1-in-the-dorsal-root-ganglia-in-mice
#18
Lei-Fang Cao, Meng Si, Ya Huang, Li-Hua Chen, Xiao-Yan Peng, Ya-Qin Qin, Teng-Teng Liu, Yan Zhou, Tong Liu, Wei-Feng Luo
Itch is a common symptom in patients with skin and systemic diseases, but the effective treatment is limited. Here, we evaluated the anti-itch effects of the botulinum toxin type A (BoNT/A) using acute and chronic dry skin itch mouse models, which were induced by compound 48/80, chloroquine, and a mixture of acetone-diethylether-water treatment, respectively. Pretreatment of intradermal BoNT/A exerted long-term inhibitory effects on compound 48/80-induced and chloroquine-induced acute itch on days 1, 3, 7, and 14, but not on day 21, in mice...
April 13, 2017: Neuroreport
https://www.readbyqxmd.com/read/28400471/a-novel-tarantula-toxin-stabilizes-the-deactivated-voltage-sensor-of-bacterial-sodium-channel
#19
Cheng Tang, Xi Zhou, Phuong Tran Nguyen, Yunxiao Zhang, Zhaotun Hu, Changxin Zhang, Vladimir Yarov-Yarovoy, Paul G DeCaen, Songping Liang, Zhonghua Liu
Voltage-gated sodium channels (NaVs) are activated by transiting the voltage sensor from the deactivated to the activated state. The crystal structures of several bacterial NaVs have captured the voltage sensor module (VSM) in an activated state, but structure of the deactivated voltage sensor remains elusive. In this study, we sought to identify peptide toxins stabilizing the deactivated VSM of bacterial NaVs. We screened fractions from several venoms and characterized a cystine knot toxin called JZTx-27 from the venom of tarantula Chilobrachys jingzhao as a high-affinity antagonist of the prokaryotic NaVs nonselective voltage-gated, Bacillus alcalophilus (NsVBa) and bacterial sodium channel from Bacillus halodurans(NaChBac) (IC50 = 112 nM and 30 nM, respectively)...
April 11, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28400258/gating-modifier-toxin-interactions-with-ion-channels-and-lipid-bilayers-is-the-trimolecular-complex-real
#20
REVIEW
Akello J Agwa, Sónia T Henriques, Christina I Schroeder
Spider peptide toxins have attracted attention because of their ability to target voltage-gated ion channels, which are involved in several pathologies including chronic pain and some cardiovascular conditions. A class of these peptides acts by modulating the gating mechanism of voltage-gated ion channels and are thus called gating modifier toxins (GMTs). In addition to their interactions with voltage-gated ion channels, some GMTs have affinity for lipid bilayers. This review discusses the potential importance of the cell membrane on the mode of action of GMTs...
April 8, 2017: Neuropharmacology
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